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1

A numerical method for predicting the performance of a randomly packed distillation column  

Microsoft Academic Search

A numerical method is proposed for modeling the distillation process in a randomly packed column. The proposed model is able to predict the axial and radial concentration distributions along the column without introducing the empirical turbulent Schmidt number or the experimentally measured turbulent mass transfer diffusivity. The present model involves the differential mass transfer equation set and the accompanied computational

Guo Biao Liu; K. T. Yu; X. G. Yuan; C. J. Liu

2009-01-01

2

Flooding characteristics of packed columns with high efficiency. [SDC protruded distillation, Podbielniak bronze Helipak, Norton pall ring, Goodloe mesh  

Microsoft Academic Search

Flooding characteristics of four high efficiency column packings, including Scientific Development Co. (SDC) protruded stainless distillation packing, Norton stainless pall rings, Podbielniak bronze Helipak, and Goodloe stainless wire mesh packing were determined experimentally. Two Plexiglas columns (6.35 cm ID and 15.2 cm ID) filled with these packings were operated with countercurrent air and water streams. Pressure drop data were recorded

W. M. Choi; R. C. Michel; J. L. P. Varlet

1976-01-01

3

Distillation columns containing structured packings: A comprehensive model for their performance. 2: Mass-transfer model  

Microsoft Academic Search

This is the second part of a two-part paper dealing with the fluid mechanics and mass transfer in structured packings for distillation column service. The first part elucidated pressure drop, flooding, and liquid holdup. The second part covers the generation of effective interfacial area and provides a general correlation for predicting the mass-transfer efficiency as a function of surface type,

J. Antonio Rocha; Jose L. Bravo; James R. Fair

1996-01-01

4

Distillation columns containing structured packings: A comprehensive model for their performance. 1. Hydraulic models  

Microsoft Academic Search

A mechanistically-based model has been developed to aid the analysis and design of distillation columns containing structured packings of the corrugated plate type. The model encompasses the important, and related, parameters of liquid holdup, pressure drop, flooding, and mass-transfer efficiency. Since it deals with the countercurrent contacting of liquid with gas or vapor, the model may also be applied to

J. Antonio Rocha; Jose L. Bravo; James R. Fair

1993-01-01

5

Counter-current operation of structured catalytically packed distillation columns: pressure drop, holdup and mixing  

Microsoft Academic Search

Structured packed columns, in which the catalyst particles are enclosed within wire gauze envelopes (“sandwiches”) are promising reactor configurations for reactive distillation and hydroconversions. By allowing preferential channels for the gas and liquid phases, counter-current operation is achieved even for millimeter sized catalyst particles without the problem of flooding. This paper reports the results of a comprehensive experimental study of

J. Ellenberger; R. Krishna

1999-01-01

6

Simultaneous heat and mass transfer of a packed distillation column for ammonia–water absorption refrigeration systems  

Microsoft Academic Search

This paper presents a study on the NH3–H2O distillation process using a packed column with liquid reflux from the condenser in an absorption refrigeration system. A differential mathematical model has been developed on the basis of mass and energy balances and the heat and mass transfer equations. A net molar flux between the liquid and vapour phases has been considered

José Fernández-Seara; Jaime Sieres; Manuel Vázquez

2002-01-01

7

Dynamics and control of a packed distillation column for the isotopic enrichment of plasma exhausts from controlled thermonuclear reactors  

Microsoft Academic Search

A control scheme is proposed based on our analysis of the disturbances expected during normal operation of the lead column in the fuel enrichment distillation cascade for a near-term tokamak fusion reactor fuel cycle. The primary objective of this control scheme is to minimize both the time and the amount that the atom percent protium in the bottoms product is

J. F. Davis; R. S. H. Mah; W. F. Stevens; B. Misra; V. A. Maroni

1979-01-01

8

Flooding Characteristics of Packed Columns with High Efficiency.  

National Technical Information Service (NTIS)

Flooding characteristics of four high efficiency column packings, including Scientific Development Co. (SDC) protruded stainless distillation packing, Norton stainless pall rings, Podbielniak bronze Helipak, and Goodloe stainless wire mesh packing were de...

W. M. Choi R. C. Michel J. L. P. Varlet

1976-01-01

9

Tritium Isotope Separation Using Adsorption-Distillation Column  

SciTech Connect

In order to miniaturize the height of a distillation tower for the detritiation of waste water from fusion reactors, two experiments were conducted: (1) liquid frontal chromatography of tritium water eluting through an adsorption column and (2) water distillation using a column packed with adsorbent particles. The height of the distillation tower depends on the height equivalent to a theoretical plate, HETP, and the equilibrium isotope separation factor, {alpha}{sub H-T}{sup equi}. The adsorption action improved not only HETP but also {alpha}{sub H-T}{sup equi}. Since the adsorption-distillation method proposed here can shorten the tower height with keeping advantages of the distillation, it may bring an excellent way for miniaturizing the distillation tower to detritiate a large amount of waste water from fusion reactors.

Fukada, Satoshi [Kyushu University (Japan)

2005-07-15

10

Optimal design of thermally coupled distillation columns  

Microsoft Academic Search

This paper considers the optimal design of thermally coupled distillation columns and dividing wall columns using detailed column models and mathematical optimization. The column model used is capable of describing both conventional and thermally coupled columns, which allows comparisons of different structural alternatives to be made. Possible savings in both operating and capital costs of up to 30% are illustrated

G. Duennebier; Constantinos C. Pantelides

1999-01-01

11

Correlate the flooding of packed columns a new way  

Microsoft Academic Search

Packed-column pressure-drop and flooding-point prediction has received new attention recently. These publications, like most earlier ones, focus on gas-flow-induced pressure drop, and flooding due to liquid entrainment in the packing. A few years ago, some problems occurred when packing was applied in high-pressure distillation service, such as ethylene and propylene superfractionators. Apparently, the maximum liquid-through-put capacity was lower than predicted

1994-01-01

12

Mass transfer efficiency of randomly-packed column: modeling considerations  

Microsoft Academic Search

This article deals with the performance of a randomly packed distillation column depending on the effective vapor–liquid interfacial area (ae) and the flood ratio (%Fl). An approach to design with respect to the derivatives of the function ae=f(%Fl) has been evaluated using %Fl due to the Eckert flooding model. The proposed log–basis equation for ae of random packings is expected

Aynur Senol

2001-01-01

13

A numerical case study of packed columns  

Microsoft Academic Search

This paper presents results concerning the validation of a recently developed packing algorithm. The basic ethos of this algorithm, known as DigiPac, is to use three-dimensional methods to digitise particle shapes, and to use this digital information directly in computations of how particles pack together without further conversion or the need for modelling. A variety of simulations of packed columns,

R. Caulkin; M. Fairweather; X. Jia; R. A. Williams

2005-01-01

14

Method for packed column separations and purifications  

DOEpatents

The invention encompasses a method of packing and unpacking a column chamber. A mixture of a fluid and a matrix material are introduced through a column chamber inlet so that the matrix material is packed within a column chamber to form a packed column. The column chamber having the column chamber inlet or first port for receiving the mixture further has an outlet port and an actuator port. The outlet port is partially closed for capturing the matrix material and permitting the fluid to flow therepast by rotating relative one to the other of a rod placed in the actuator port. Further rotation relative one to the other of the rod and the column chamber opens the outlet and permits the matrix material and the fluid to flow therethrough thereby unpacking the matrix material from the column chamber.

Holman, David A. (Richland, WA); Bruckner-Lea, Cynthia J. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Chandler, Darrell P. (Richland, WA)

2006-08-15

15

Effects of water on steam rectification in a packed column  

Microsoft Academic Search

The effects of water on steam rectification, i.e., multi-stage saturated steam distillation, were investigated in a packed column. N-octane–p-xylene and 1,3,5-trimethylbenzene–1,2,4-trimethylbenzene were used as test systems. Both binary systems are nearly ideal systems and insoluble in water, thus the effects of water in steam rectification can be clearly and definitely revealed. Such unpolar organic liquid is named as “oil”. The

Qingli Qian; Hongxing Wang; Peng BAI; Guoqing Yuan

2011-01-01

16

Analysis of finishing reactive distillation columns  

SciTech Connect

In this paper, a novel method to deal with the design and the synthesis of finishing reactive distillation columns with one reactive core, two rectifying sections, and one stripping section is presented. The attention of the work is concentrated on three subjects: (1) the feasibility of a given separation at both finite and total reflux operation; (2) the minimum energy demand operation; (3) the distribution of the reaction between the reactor and the finishing reactive column. The design problem presents the same grade of difficulty as that found in the design of conventional extractive columns. A geometric based method is used to explain key features of reactive distillation. Here, the relation between the reaction yield and the distillate flow rate plays a role similar to that of the entrainer flow in extractive distillation. Hence, special attention is given to the behavior of the profiles inside the rectifying section below the reactive core. The methodology is illustrated using the well-known MTBE case study.

Espinosa, J.; Aguirre, P.; Frey, T.; Stichlmair, J. [Technische Univ. Muenchen, Garching (Germany). Lehrstuhl A fuer Verfahrenstechik] [Technische Univ. Muenchen, Garching (Germany). Lehrstuhl A fuer Verfahrenstechik

1999-01-01

17

A Versatile, Automatic Chromatographic Column Packing Device  

ERIC Educational Resources Information Center

Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)

Barry, Eugene F.; And Others

1977-01-01

18

Pressure drop of internals for packed columns  

Microsoft Academic Search

Because of their low pressure drop per equilibrium stage, random and particularly structured packings are frequently used in vacuum distillation. For applications requiring operation at absolute pressures below 100mbar usually the total allowable pressure drop is specified. Demanding separations require frequent collection and redistribution of liquid. This means dealing with an additional source of pressure drop which is usually ignored,

A. Rix; Z. Olujic

2008-01-01

19

Final Report, Distillation Column Flooding Predictor  

SciTech Connect

The Flooding Predictor is an advanced process control strategy comprising a patented pattern-recognition methodology that identifies pre-flood patterns discovered to precede flooding events in distillation columns. The grantee holds a U.S. patent on the modeling system. The technology was validated at the Separations Research Program, The University of Texas at Austin under a grant from the U. S. Department of Energy, Inventions & Innovation Program. Distillation tower flooding occurs at abnormally high vapor and/or liquid rates. The loss in tray efficiencies is attributed to unusual behavior of liquid inventories inside the column leading to conditions of flooding of the space in between trays with liquid. Depending on the severity of the flood condition, consequences range from off spec products to equipment damage and tower shutdown. This non-intrusive pattern recognition methodology, processes signal data obtained from existing column instrumentation. Once the pattern is identified empirically, it is modeled and coded into the plant's distributed control system. The control system is programmed to briefly "unload" the tower each time the pattern appears. The unloading takes the form of a momentary reduction in column severity, e.g., decrease bottom temperature, reflux or tower throughput. Unloading the tower briefly at the pre-flood state causes long-term column operation to become significantly more stable - allowing an increase in throughput and/or product purity. The technology provides a wide range of value between optimization and flooding. When a distillation column is not running at capacity, it should be run in such a way ("pushed") that optimal product purity is achieved. Additional benefits include low implementation and maintenance costs, and a high level of console operator acceptance. The previous commercial applications experienced 98% uptime over a four-year period. Further, the technology is unique in its ability to distinguish between different flooding mechanisms within the same tower, e.g., liquid and jet flooding.

George E. Dzyacky

2003-05-31

20

Small scale ethanol production demonstration: comparison of packed versus plate rectifying column  

SciTech Connect

The Johnson Environmental and Energy Center with assistance from the Madison County Farm Bureau Association received a grant in 1980 from the US Department of Energy to design, fabricate, and evaluate a small scale continuous ethanol plant. In 1981, the Center received a second DOE grant to compare the economics of replacing the plate rectifying column in the initial unit with a packed rectifying column. The results of the study indicate that the distillation unit with the packed rectifying column is capable of producing 14 gallons per hour of 170 proof ethanol. The energy ratio for distillation was a positive 2:1. Cost of the packed column was considerably less than the plate column. 1 reference, 19 figures, 9 tables.

Adcock, II, L E; Eley, M H; Schroer, B J

1982-07-01

21

Continuous and Batch Distillation in an Oldershaw Tray Column  

ERIC Educational Resources Information Center

The importance of distillation in the separation field prompts the inclusion of distillation experiments in the chemical engineering curricula. This work describes the performance of an Oldershaw column in the rectification of a cyclohexane/n-heptane mixture. Total reflux distillation, continuous rectification under partial reflux, and batch…

Silva, Carlos M.; Vaz, Raquel V.; Santiago, Ana S.; Lito, Patricia F.

2011-01-01

22

Gamma scanning evaluation for random packed columns  

Microsoft Academic Search

In the present study, the liquid (water) holdup distribution was measured in a packed column (7.62 cm diameter) filled with 0.9 cm glass Rashig rings using noninvasive gamma ray technique. Three different radioactive sources: 11.1 MBq 60Co (1133 keV), 74 GBq 131I (380 keV), and 740 GBq 99mTc (140 keV) with a CsI(Tl) detector coupled to a photodiode were used

Vasquez PAS; F. E. Costa; P. R. Rela; W. A. P. Calvo; G. A. C. LeRoux; M. M. Hamada

2005-01-01

23

Fuzzy rule-based controller for binary distillation column  

Microsoft Academic Search

In this paper a fuzzy logic based control scheme has been proposed for distillation column. Fuzzy Inference Systems (FIS) is proposed to adjust the manipulated variables to get the desired composition of products for a binary distillation column. To control the top and bottom product composition two separate fuzzy inference systems has been designed. The scheme uses fuzzy rules and

Amit Kumar Singh; Barjeev Tyagi; Vishal kumar

2011-01-01

24

Internally Heat-Integrated Distillation Columns: A Review  

Microsoft Academic Search

The heat-integrated distillation column to be addressed in this paper is a special distillation column that involves internal heat integration between the whole rectifying and the whole stripping sections. An overview of the research on this process is presented in this work. It covers from the thermodynamic development and evaluations to the practical design and operation investigations for the process.

M. Nakaiwa; K. Huang; A. Endo; T. Ohmori; T. Akiya; T. Takamatsu

2003-01-01

25

Design and construction of a packed column simulator operating under atmospheric and reduced pressure  

NASA Astrophysics Data System (ADS)

Distillation under reduced pressure for the separation of constituants is considered. To avoid thermic damage in columns, the most important parameters are pressure loss and resistance time. The development of a simulator, enabling the determination of the hydrodynamic parameters with the mixture air-water under different pressures for any given mixture, is carried out. A bibliographic study and a reference study, performed with a test mixture on a pilot column under reduced pressure, packed with Raschig ring are presented. The simulator and the results obtained are reported. The main hydrodynamic parameters such as pressure drop, hold-ups and flooding rate were taken into account. The packed column was considered as a reactor and the results of the residence time distribution are reported. Theoretical models show that the packed column behaves as an association of continuous stirred-tank reactors in series. A comparison between the actual column results and the simulator results demonstrate the accuracy of the simulation.

Messaoudene, Abdelhamid

1989-03-01

26

Flows of dilute polymer solutions through packed porous chromatographic columns  

Microsoft Academic Search

Summary We have found that diffusion of polystyrene into the micropores of packed porous chromatographic columns of a type used for size separations of macromolecules is strongly influenced by the flow rate of the polymer solution through the column and also by the macromolecular size and internal pore size of the column packing. Dilute polymer solutions (0.05 wt.% polystyrene in

J. H. Aubert; M. Tirrell

1980-01-01

27

Correlate the flooding of packed columns a new way  

SciTech Connect

Packed-column pressure-drop and flooding-point prediction has received new attention recently. These publications, like most earlier ones, focus on gas-flow-induced pressure drop, and flooding due to liquid entrainment in the packing. A few years ago, some problems occurred when packing was applied in high-pressure distillation service, such as ethylene and propylene superfractionators. Apparently, the maximum liquid-through-put capacity was lower than predicted from the gas-flow-induced flooding correlations. Such situation exists when predicting the performance of valve trays in similar service: liquid downflow can be limiting before entrainment flooding occurs. The reason for this behavior is the relatively low liquid and high vapor density of these high-pressure services. The liquid/vapor density ratios are typically 10--15:1 for such hydrocarbon systems. In contrast, for low-pressure water/air systems, this ratio is in the range 300--800:1. A large amount of experimental data for low-pressure systems has been used to correlate pressure drop and flooding, but it doesn't cover the technically important region of low liquid and high vapor density. This Article suggests an approach for understanding such liquid-limited systems.

Kaiser, V.

1994-06-01

28

Miniature Distillation Column for Producing LOX From Air  

NASA Technical Reports Server (NTRS)

The figure shows components of a distillation column intended for use as part of a system that produces high-purity liquid oxygen (LOX) from air by distillation. (The column could be easily modified to produce high-purity liquid nitrogen.) Whereas typical industrial distillation columns for producing high-purity liquid oxygen and/or nitrogen are hundreds of feet tall, this distillation column is less than 3 ft (less than about 0.9 m) tall. This column was developed to trickle-charge a LOX-based emergency oxygen system (EOS) for a large commercial aircraft. A description of the industrial production of liquid oxygen and liquid nitrogen by distillation is prerequisite to a meaningful description of the present miniaturized distillation column. Typically, such industrial production takes place in a chemical processing plant in which large quantities of high-pressure air are expanded in a turboexpander to (1) recover a portion of the electrical power required to compress the air and (2) partially liquefy the air. The resulting two-phase flow of air is sent to the middle of a distillation column. The liquid phase is oxygen-rich, and its oxygen purity increases as it flows down the column. The vapor phase is nitrogen-rich and its nitrogen purity increases as it flows up the column. A heater or heat exchanger, commonly denoted a reboiler, is at the bottom of the column. The reboiler is so named because its role is to reboil some of the liquid oxygen collected at the bottom of the column to provide a flow of oxygen-rich vapor. As the oxygen-rich vapor flows up the column, it absorbs the nitrogen in the down-flowing liquid by mass transfer. Once the vapor leaves the lower portion of the column, it interacts with down-flowing nitrogen liquid that has been condensed in a heat exchanger, commonly denoted a condenser, at the top of the column. Liquid oxygen and liquid nitrogen products are obtained by draining some of the purified product at the bottom and top of the column, respectively. Because distillation is a mass-transfer process, the purity of the product(s) can be increased by increasing the effectiveness of the mass-transfer process (increasing the mass-transfer coefficient) and/or by increasing the available surface area for mass transfer through increased column height. The diameter of a distillation column is fixed by pressure-drop and mass-flow requirements. The approach taken in designing the present distillation column to be short yet capable of yielding a product of acceptably high purity was to pay careful attention to design details that affect mass-transfer processes.

Rozzi, Jay C.

2006-01-01

29

Mechanistic pressure drop model for columns containing structured packings  

Microsoft Academic Search

A mechanistic model was developed to predict pressure drop and flooding in packed columns equipped with corrugated packing of the regular type. It was developed after considering the interaction of falling liquid film with the gas phase, based on mass- and momentum-conservation equations. Among the most common structured packings, the behavior of the Mellapak and BX types was analyzed. The

E. Brunazzi; Alessandro Paglianti

1997-01-01

30

Automated column equilibration, washing, sample loading and elution of bench-packed mini-columns.  

PubMed

In this paper we describe an easy and efficient way to pack mini-columns and use them in the Biomek 1000 Automated Laboratory Workstation. These procedures allow for automated column equilibration, column washing, sample loading and elution, and utilization of commercially available components. Various resins can be packed, allowing for automation of a variety of procedures in which minicolumns are used. PMID:1571139

Jagadeeswaran, P

1992-03-01

31

Resilient and Robust Control of an Energy Integrated Distillation Column  

Microsoft Academic Search

A distillation column equipped with an intermediate condenser for energy conservation was studied using advanced multivariable control techniques. The intermediate condenser heat duty was successfully used as an extra manipulated variable, giving rise to non-square three input-two output control system designs. The material balance control structure had much better performance than the energy balance structure. The primary advantage of the

B. Wayne Bequette; Robert R. Horton; Thomas F. Edgar

1987-01-01

32

Applying risk assessment principles to a batch distillation column  

SciTech Connect

Some distillation columns in the chemical industry are operated in batch mode with a fairly short operating cycle. At the end of each cycle the columns are cooled and recharged. During the cooling cycle, air will be drawn into the column by the action of a vacuum relief valve. Consequently, for a finite portion of the operating cycle a flammable mixture will exist in the column. Here we evaluate the risk posed by such an operation to see if a mitigation measure is justified. We develop a fault tree and estimate the frequency of ignition by all possible ignition sources. By comparing the risk reduction attainable by installing a lightning protection system with that attainable by using an inert blanketing system the lightning protection system is found to be the preferred solution. It provides about the same risk reduction at a lower overall cost. 2 refs., 3 figs., 4 tabs.

Woodward, J.L.; Moosemiller, M.D. [DNV Technica, Columbus, OH (United States)] [DNV Technica, Columbus, OH (United States)

1996-12-31

33

Mechanistic pressure drop model for columns containing structured packings  

SciTech Connect

A mechanistic model was developed to predict pressure drop and flooding in packed columns equipped with corrugated packing of the regular type. It was developed after considering the interaction of falling liquid film with the gas phase, based on mass- and momentum-conservation equations. Among the most common structured packings, the behavior of the Mellapak and BX types was analyzed. The aim of this work is to demonstrate how mechanistic models, developed for simple geometry, can also be used to compute pressure drops in cases where the geometry is more complex, as with a structured packing. This approach, based on the geometric characteristics of the packing and measurable parameters such as liquid holdup, enables the development of a basic model by limiting the number of adjustable parameters, which are numerous in all the available models. Because of its nature, this model is extremely easy to extend to different types of structured packings.

Brunazzi, E.; Paglianti, A. [Industrial Chemistry and Materials Science, Pisa (Italy). Dept. of Chemical Engineering

1997-02-01

34

Experimental investigation of conventional control strategies for a heterogeneous azeotropic distillation column  

Microsoft Academic Search

In this work, a laboratory scale sieve plate distillation column was constructed to investigate the conventional control strategies of an isopropyl alcohol (IPA), cyclohexane (CyH) and water (H2O) heterogeneous azeotropic distillation column. Steady state process analysis showed that the optimal operation point should be located at a critical reflux, a transition point at which the distillation path switches from a

I-L Chien; C. J Wang; D. S. H Wong; C.-H Lee; S.-H Cheng; R. F Shih; W. T Liu; C. S Tsai

2000-01-01

35

Mass transfer of volatile organics in a packed column  

Microsoft Academic Search

Interphase mass transfer kinetics of several organic compounds in the air-water system were investigated in a countercurrent flow packed column. Oxygen and water mass transfer was studied simultaneously, to provide in-system reference substance data for single-phase limited compounds. Flooding studies were conducted to determine allowable air and water loadings at the desired air:water ratios. Column flooding points were accurately predicted

Mumford

1987-01-01

36

Fused silica capillary micro-packed columns in gas chromatography  

Microsoft Academic Search

Summary  Flexibility, strength and adsorption inertness of fused-silica capillaries permits their extensive application for the preparation\\u000a of micro-packed columns in gas chromatography. Decreasing the column diameter (from 0.5 to 0.15 mm) and the diameter of the\\u000a sorbent particles (from 100 to 5 ?m) results in a marked reduction of the height equivalent to a theoretical plate (HETP),\\u000a as well as in

A. Malik; V. G. Berezkin; V. S. Gavrichev

1984-01-01

37

An Economical Criterion for Packed Absorption Column Design  

Microsoft Academic Search

In the last few years an increasing number of restrictions have been introduced to limit pollutant emissions into the environment and, on the other hand, industry requires internals that reduce, both, operating costs and dimensions of absorption columns. In the present work, besides some new experimental data on pressure drop and mass transfer efficiency of a new structured packing, an

E. Brunazzi; G. Nardini; A. Paglianti

38

Flooding and Mass Transfer in Goodloe-Packed Columns.  

National Technical Information Service (NTIS)

Flooding and mass transfer experiments were performed with a CO sub 2 -air/water system to examine mass transfer characteristics in Goodloe-packed columns of 6.4 and 15.2-cm ID for removal of radioactive Kr from HTGR off-gas. The flooding experiments veri...

E. I. Chao R. J. Bertolami J. L. P. Varlet G. R. Wilkes

1976-01-01

39

Hydrodynamics of a packed countercurrent column for the gas extraction  

Microsoft Academic Search

The hydraulic capacity of a countercurrent column with gauze packing was examined at pressures between 8 and 30 MPa and temperatures between 313 and 373 K. The systems used were water + carbon dioxide, aqueous surfactant solution + carbon dioxide, and Toco, a substance whose physical properties are roughly similar to those of α-Tocopherol + carbon dioxide. A distinctive change

Ron Stockfleth; Gerd Brunner

1999-01-01

40

Stationary phases for packed-column supercritical fluid chromatography.  

PubMed

The properties of silica-based, chemically bonded, packed column stationary phases used in supercritical fluid chromatography are described with a focus on column design and retention mechanisms. Supercritical fluid chromatography has benefited substantially from innovations in column design for liquid chromatography even if the separation conditions employed are generally quite different. The mobile phase composition and column operating conditions play an interactive role in modifying selectivity in supercritical fluid chromatography by altering analyte solubility in the mobile phase and through selective solvation of the stationary phase resulting in a wider range and intensity of intermolecular interactions with the analyte. The solvation parameter model is used to identify the main parameters that affect retention in supercritical fluid chromatography using carbon dioxide-methanol as a mobile phase and as a basis for column characterization to facilitate the identification of stationary phases with different separation characteristics for method development. As a caution it is pointed out that these column characterization methods are possibly a product of both the stationary phase chemistry and the column operating conditions and are suitable for use only when columns of similar design and with similar operating conditions are used. PMID:22209357

Poole, Colin F

2012-08-10

41

Tests of isotopic separation efficiency of palladium packed columns  

SciTech Connect

The isotopic effect of palladium has been applied in different ways to separate hydrogen isotopes for many years. At Savannah River Site palladium deposited on kieselguhr (Pd/k) is used in a thermal cycling absorption process (TCAP) to purify tritium for over ten years. The need to design columns for different throughputs and the desire to advance the performance of TCAP created the need to evaluate different column designs and packing materials for their separation efficiency. In this work, columns with variations in length, diameter and metal foam presence were tested using an isotope displacement method. A simple computer model was also developed to calculate the number of theoretical separation stages based on the test results. The effects of column diameter, metal foam presence and gas flow rate were identified. (authors)

Heung, L. K.; Staack, G. C.; Klein, J. E.; Jacobs, W. D. [Savannah River National Laboratory, 773-A, Savannah River Site, Aiken, SC 29808 (United States)

2008-07-15

42

Gas-solid trickle flow hydrodynamics in a packed column  

Microsoft Academic Search

The pressure gradient and the static and the dynamic hold-up have been measured for a system consisting of a Fluid Cracking Catalyst (FCC) of 30–150 × 10?6 m diameter, trickling over a packed bed and with a gas streaming in countercurrent flow. The experiments were carried out at ambient conditions using a glass column of 25 × 10?3 m diameter.

K. R. Westerterp; M. Kuczynski

1987-01-01

43

Reactive extraction of lactic acid in a packed column  

Microsoft Academic Search

Reactive extraction of lactic acid was performed continuously in a packed column. The 0.6 M trioctylamine (TOA)\\/l-chlorobutane\\u000a system was used as an extradant. The initial concentration of lactic acid was 10 wt% based on fermentation results. Raschig\\u000a rings (5 and 7 mm diameter) were used to measure hydrodynamic data. Disperse phase holdup was nearly constant at Vdd,f.It can be seen

Dong Hoon Han; Won Hi Hong

1998-01-01

44

Flooding rates and holdup in packed liquid--liquid extraction columns  

Microsoft Academic Search

Countercurrent flow of liquids in columns packed with Raschig rings was studied with fluids having a wide range of physical properties. These results, along with data reported previously from other studies, were used to develop a correlation for predicting flooding rates in packed columns that is significantly better than previous correlations. Dispersed phase holdup in packed columns can be estimated

J. S. Watson; L. E. McNeese; John Day; P. A. Carroad

1975-01-01

45

Development of a scintillator detector system for ?-ray scan measurements of industrial distillation columns  

Microsoft Academic Search

A CsI(Tl) scintillator detector set was developed for ?-ray scan measurements aiming to identify process failures in distillation columns of an industrial petrochemical plant. A system with a 60Co sealed source as a ?-ray emitter and the developed CsI(Tl) detector were applied to evaluate the performances in a simulated model of a tray-type distillation column.

Pablo A. Vásquez S; Fabio E. Costa; Wilson A. P. Calvo; Margarida M. Hamada

2005-01-01

46

Nonlinear Model Predictive Control of High Purity Distillation Columns for Cryogenic Air Separation  

Microsoft Academic Search

High purity distillation columns are critical unit operations in cryogenic air separation plants that supply purified gases to a number of industries. We have developed a nonlinear model predictive control (NMPC) strategy based on the assumption of full-state feedback for a prototypical cryogenic distillation column to allow effective operation over a wide range of plant production rates. The controller design

Zhongzhou Chen; Michael A. Henson; Paul Belanger; Lawrence Megan

2010-01-01

47

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2004-08-24

48

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2006-02-21

49

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components  

DOEpatents

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Egorov, Oleg B. (Richland, WA); O'Hara, Matthew J. (Richland, WA); Grate, Jay W. (West Richland, WA); Chandler, Darrell P. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Bruckner-Lea, Cynthia J. (Richland, WA)

2000-01-01

50

Experimental investigation of optimal conventional control strategy for a heterogeneous azeotropic distillation column  

Microsoft Academic Search

In this work, a laboratory scale sieve plate distillation column was constructed to investigate the optimum conventional control strategy of an isopropyl alcohol(IPA), cyclohexane(CyH) and water(H20) heterogeneous azeotropic distillation column. Steady state process analysis showed that the optimal operation point should be located at a critical reflux, a transition point at which the distillation path switches from a route that

R. F. Shih; W. T. Liu; C. S. Tsai; C.-H. Lee; S.-H. Cheng

1999-01-01

51

Cascaded process model based control: packed absorption column application.  

PubMed

Nonlinear, adaptive, process-model based control is demonstrated in a cascaded single-input-single-output mode for pressure drop control in a pilot-scale packed absorption column. The process is shown to be nonlinear. Control is demonstrated in both servo and regulatory modes, for no wind-up in a constrained situation, and for bumpless transfer. Model adaptation is demonstrated and shown to provide process insight. The application procedure is revealed as a design guide to aid others in implementing process-model based control. PMID:24176668

Govindarajan, Anand; Jayaraman, Suresh Kumar; Sethuraman, Vijayalakshmi; Raul, Pramod R; Rhinehart, R Russell

2014-03-01

52

Axial development and radial non-uniformity of flow in packed columns.  

PubMed

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 microm diameter porous polyacrylamide, or 99 or 780 microm diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 microm polymeric beads. The packing methods included gravity settling, slurry packing, ultrasonication, and dry packing with vibration. The magnetic resonance method used averaged apparent fluid velocity over both column cross-sections and fluid displacements greater than one particle diameter and hence permits assessment of macroscopic flow non-uniformities. The results confirm that now non-uniformities induced by the conical distributor of the 11.7-mm I.D. column or the presence of voids at the column entrance relax on a length scale of the column radius. All of the 11.7-mm I.D. columns examined exhibit near wall channeling within a few particle diameters of the wall. The origins of this behavior are demonstrated by imaging of the radial dependence of the local porosity for a column packed with 780 microm beads. Columns packed with the 99-microm beads exhibit reduced flow in a region extending from ten to three-to-five particle diameters from the wall. This velocity reduction is consistent with a reduced porosity of 0.35 in this region as compared to approximately 0.43 in the bulk of the column. Ultrasonicated and dry-packed columns exhibit enhanced flow in a region located between approximately eight and 20 particle diameters from the wall. This enhancement maybe caused by packing density inhomogeneity and/or particle size segregation caused by vibration during the packing process. No significant non-uniformities on length scales of 20 microm or greater were observed in the commercially packed column packed with 10 microm particles. PMID:11860146

Park, Jaekeun C; Raghavan, Karthik; Gibbs, Stephen J

2002-02-01

53

Startup of distillation columns using profile position control based on nonlinear wave model  

SciTech Connect

Startup of distillation columns is a very challenging control problem because of its strong nonlinearity and a wide operating range during the transient period. A nonlinear wave model captures the essential dynamic behavior of the distillation process so that it is possible to deal with the difficulties encountered during startup operation. This paper is concerned with the startup of distillation systems using nonlinear wave model based control developed by Han and Park. This control scheme uses profile positions as controlled variables and is based on the nonlinear wave model by Hwang and generic model control scheme by Lee and Sullivan. It can be applied to a binary or a multicomponent distillation system that can be represented as a pseudobinary. The proposed control scheme is shown by simulation studies to provide a safe and economic startup operation not only for dual composition control of a simple distillation column but also for a complex distillation configuration.

Han, M.; Park, S. [Chungnam National Univ., Taejon (Korea, Republic of). Chemical Engineering Dept.] [Chungnam National Univ., Taejon (Korea, Republic of). Chemical Engineering Dept.; [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Chemical Engineering Dept.

1999-04-01

54

Assessing Safety in Distillation Column Using Dynamic Simulation and Failure Mode and Effect Analysis (FMEA)  

NASA Astrophysics Data System (ADS)

Safety assessment becomes an important activity in chemical industries since the need to comply with general legal requirements in addition to meet safer plant and profit. This paper reviews some most frequently causes of distillation column malfunction. First, analysis of case histories will be discussed for providing guidelines in identifying potential trouble spots in distillation column. A dynamic simulation for operational failure is simulated as the basis for assessing the consequences. A case study will be used from a side stream distillation column to show the implementation of the concept. A framework for assessing safety in the column is proposed using Fault Mode and Effect Analysis (FMEA). Further, trouble-free operation in order to reduce the risk associated with column malfunction is described.

Werner, Suhendra; Fred, Witt; Compart

55

Exact electric field strength over the packed capillary electrochromatography column bed, theoretical considerations and practical determination.  

PubMed

On the basis of the experiments, it was proved that Ohm's law holds true in a capillary electrochromatography (CEC) column. By using the additivity of the potential drop over the packed and unpacked sections, the exact values of the electric field strength over the packed CEC column bed were determined experimentally. The ratio of the resistance of packed CEC column sections to that of an open capillary of the same length (Rp/Ro,Lp) were calculated. Some theoretical calculations were made to show how some structural parameters of particle lattice affect the resulting Rp/Ro,Lp value of the column bed formed accordingly. It is suggested that to correctly elucidate the EOF phenomenon in a CEC column, the potential drop over the packed and unpacked column sections, Ep and Eo, should be accounted for respectively, rather than using the average field strength over the total column length. PMID:15628139

Guo, Wei; Yang, Changhua; Xu, Bingjiu

2004-12-01

56

Influence of liquid redistributors on the mass-transfer efficiency of packed columns  

Microsoft Academic Search

In industrial mass-transfer columns liquid distributors and redistributors are used to mix the liquid after a certain random packing or structured packing height before it is applied to the next bed. The purpose of this is to counter a possible deterioration of the mass-transfer efficiency along the height of the column as a result of wall flow tendency of the

M. Schultes

2000-01-01

57

Low-order dynamic modeling of cryogenic distillation columns based on nonlinear wave phenomenon  

Microsoft Academic Search

A low-order dynamic model based on nonlinear wave theory is developed for a cryogenic distillation column used for nitrogen purification. By tracking the wave front propagating through the column, a simple mathematical model capable of describing the essential column dynamics is derived. The combined reboiler\\/condenser system is modeled using rigorous mass and energy balances. The low-order model is compared with

Guang-Yan Zhu; Michel A. Henson; Lawrence Megan

2001-01-01

58

Development of a mathematical model of a packed column for benzene removal from salt solutions  

SciTech Connect

A mathematical model of a packed column was developed to describe the removal of benzene from radioactive salt solutions at the Savannah River Site. The model was developed from existing, generalized mass transfer correlations for randomly dumped packing, and the correlations were adapted for structured packing. Thermophysical data specific to the solutions of interest were incorporated into the model. Verification of the code was completed using operating data from stripping columns at other locations.

Georgeton, G.K.

1989-01-01

59

Development of a mathematical model of a packed column for benzene removal from salt solutions  

SciTech Connect

A mathematical model of a packed column was developed to describe the removal of benzene from radioactive salt solutions at the Savannah River Site. The model was developed from existing, generalized mass transfer correlations for randomly dumped packing, and the correlations were adapted for structured packing. Thermophysical data specific to the solutions of interest were incorporated into the model. Verification of the code was completed using operating data from stripping columns at other locations.

Georgeton, G.K.

1989-12-31

60

A modified model of computational mass transfer for distillation column  

Microsoft Academic Search

The computational mass transfer (CMT) model is composed of the basic differential mass transfer equation, closing with auxiliary equations, and the appropriate accompanying CFD formulation. In the present modified CMT model, the closing auxiliary equations c2¯–?c [Liu, B.T., 2003. Study of a new mass transfer model of CFD and its application on distillation tray. Ph.D. Dissertation, Tianjin University, Tianjin, China;

Z. M. Sun; K. T. Yu; X. G. Yuan; C. J. Liu

2007-01-01

61

Supercritical-Fluid Chromatography in Packed and Open-Tubular Columns.  

National Technical Information Service (NTIS)

The intermediate position of SFC between GC and LC is nicely reflected in the choice of the column type. In GC, the majority of the applications is performed on open-tubular columns, whereas LC is almost exclusively carried out on packed columns. After a ...

J. G. M. Janssen

1991-01-01

62

Hydrodynamics and mass transfer coefficients for a modified Raschig ring packed column  

NASA Astrophysics Data System (ADS)

The pressure drop, the liquid holdup, as well as the liquid film mass transfer coefficients (kL) for a modified Raschig packing, with turbulence promoters, used in absorption columns, were determined experimentally. The aim of this work is to verify the improved mass transfer properties of this new packing for the randomly and, particularly, for the arranged packed columns. The experiments were performed at gas velocities ranging from 800 to 2,000 m h-1 and liquid velocities scaling between 2.5 and 8.11 m h-1, ranges that cover most of the absorption column operation conditions. Experimental data and correlations for the pressure drop, the liquid holdup and the gas-liquid mass transfer coefficients (kL) for modified Raschig ring packed columns are presented. The influence of the gas and the liquid velocities on the column hydrodynamics and the mass transfer coefficients have been obtained experimentally and also, have been compared with literature data.

Mamaliga, I.; Sidor, D.; Condurat, C.; Iacob Tudose, E. T.

2014-04-01

63

Study of arrangements for distillation of quaternary mixtures using less than N-1 columns  

Microsoft Academic Search

The design and dynamic properties of distillation sequences using side-stream columns with less than N-1 columns for separations of four-component mixtures are studied. Total annual cost and dynamic properties (using singular value decomposition) are used to compare the proposed arrangements with conventional cases. Quaternary feeds containing hydrocarbons were analyzed. For systems with low concentrations of one component in the feed,

Dulce María Méndez-Valencia; María Vázquez-Ojeda; Juan Gabriel Segovia-Hernández; Héctor Hernández; Adrián Bonilla-Petriciolet

2008-01-01

64

Development of gamma-ray scanning facilities for on-line investigation of distillation columns.  

National Technical Information Service (NTIS)

Gamma-ray scanning facilities for on-line investigation of distillation columns which is based on the attenuation of gamma radiation was developed at the Unit Tenaga Nuklear. The system utilised Co-60 or Cs-137 as a gamma-ray emitter and NaI(Tl) detector ...

Mohd Azmi bin Ismail Jaafar bin Abdullah Jamaludin bin Omar

1994-01-01

65

Experiments with a TAME Catalytic Distillation Column Using a Pellet Type Catalyst.  

National Technical Information Service (NTIS)

This report describes the experiments made with pellet type ion exchange resin catalyst in a reactive distillation column. The catalyst used was standard ion-exchange resin Amberlyst 15 H sieved so that maximum particle diameter was 0.71 mm and catalyst w...

K. Klemola A. Pyhaelahti

1994-01-01

66

Parametric study of an ethanol–water distillation column with direct vapour recompression heat pump  

Microsoft Academic Search

Heat pumps have been used to reduce energy consumption in distillation columns. However, the effects of some parameters have not been taken into consideration in the determination of energy consumption in such systems. Perhaps this is one of the reasons for little or no application of the system in ethanol which is fast becoming a competitive fuel to petrol. The

Christopher Enweremadu; Adekojo Waheed; Jeremiah Ojediran

2009-01-01

67

Using a distributed control system (DCS) for distillation column control in an undergraduate unit operations laboratory  

Microsoft Academic Search

This paper presents the main advantages of using an industrial distributed control system (DCS) in the operation of a distillation column which is used in an undergraduate unit operations laboratory course at the University of Texas at Austin. Taking advantage of the resources of an industrial DCS (friendly display options, an alarm management system, historical databases and advanced control tools),

Ivan Castillo; Thomas F. Edgar

2009-01-01

68

COMPARISON OF OZONE CONTACTORS FOR MUNICIPAL WASTEWATER EFFLUENT DISINFECTION, PACKED COLUMN VERSUS JET SCRUBBER  

EPA Science Inventory

Pilot scale investigations were made comparing two ozone contactors, a jet scrubber and a packed column, for ozone utilization and effluent coliform reduction efficiency. The contactors were operated in three phases: (1) Batch operational phase contactors were operated separately...

69

Laboratory studies of the behavior of undissolved solids in both pulsed and packed column extraction systems  

SciTech Connect

A substantial fraction of the finely divided undissolved solid material found in nuclear fuel reprocessing dissolver-product solutions is hydrophobic and tends to ``seek`` any organic-aqueous interface existing within countercurrent liquid-liquid extraction systems. While passing through pulsed-type columns this material is swept out of the aqueous phase by the combined surface area of the tiny bubbles of dispersed phase. Because these bubbles have a net velocity towards the end of the column where the nominal interface is located, the solids are swept in that direction too. These solids tend to gather in a three-phase ``crud`` layer at the nominal interface point. At equilibrium, about the same amount breaks off from the crud layer and escapes into the liquid exiting from that end of the column as enters it from the other side. If large enough, the crud layer can even interfere with interface detection and control equipment. In packed-column extraction systems, an additional problem is that feed solids can accumulate within the packing material to the point that the column `` floods`` or even totally plugs. The keys to preventing solids-related problems is the correct choice of interface level, and with packed columns, the addition of a ``pulsing leg`` at the bottom of the column. Pulsing packed column systems not only prevents solids from settling onto packing material but it also increses the number of theoretical stages available for extraction. 3 figs., 2 tabs.

Siemer, D.D.

1989-04-18

70

Hydrodynamic behaviour of a gas—solid counter-current packed column at trickle flow  

Microsoft Academic Search

Trickle flow of a more or less fluidized catalyst through a packed column is a promising new gas—solid counter-current operation. The hydrodynamic, behaviour of such a column, filled with dumped PALL rings, has been investigated, while some results have been obtained with RASCHIG rings and cylindrical screens as packing. The solid used was a microspherical catalyst carrier. Pressure drop, hold-up,

A. W. M. Roes; Swaaij van W. P. M

1979-01-01

71

Flooding and mass transfer in Goodloe-packed columns, Part 2. [HTGR  

Microsoft Academic Search

Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20°C and about 20 atm pressure. Flooding points and an overall mass transfer coefficient for Goodloe-packed columns were determined with a carbon dioxide-air-water system for 6.4 and 15.2-cm-ID

J. S. Ayala; B. W. Brian; A. C. Sharon

1977-01-01

72

Sulfur-isotope separation by distillation  

SciTech Connect

Sulfur-isotope separation by low-temperature distillation of hydrogen sulfide was studied in an 8-m, 25-mm diameter distillation column. Column temperature was controlled by a propane-propylene heat pipe. Column packing HETP was measured using nitric oxide in the column. The column was operated at pressures from 45 to 125 kPa. The relative volatility of S-32 vs. S-34 varied from 1.0008 to 1.0014.

Mills, T.R.

1982-01-01

73

CALCULATION PROCEDURE FOR FLOODING IN PACKED COLUMNS USING A CHANNEL MODEL  

Microsoft Academic Search

The combined effect of a channel-based approach for dry pressure drop and the Buchanan equation for wet pressure drop in packed beds has been numerically evaluated within the flooding region. The flooding point is an important design parameter since it establishes the maximum hydrodynamic capacity at which a packed column can operate. Upon analyzing the aforementioned approach, it was found

Elisabetta Brunazzi; Ricardo Macías-Salinas; Aurora Viva

2008-01-01

74

Design and Operation of Cryogenic Distillation Research Column for Ultra-Low Background Experiments  

NASA Astrophysics Data System (ADS)

Motivated by isotopically enriched germanium (76Ge and 73Ge) for monocrystalline crystal growth for neutrinoless double-beta decay and dark matter experiments, a cryogenic distillation research column was developed. Without market availability of distillation columns in the temperature range of interest with capabilities necessary for our purposes, we designed, fabricated, tested, refined and operated a two-meter research column for purifying and separating gases in the temperature range from 100-200K. Due to interest in defining stratification, purity and throughput optimization, capillary lines were integrated at four equidistant points along the length of the column such that real-time residual gas analysis could guide the investigation. Interior gas column temperatures were monitored and controlled within 0.1oK accuracy at the top and bottom. Pressures were monitored at the top of the column to four significant figures. Subsequent impurities were measured at partial pressures below 2E-8torr. We report the performance of the column in this paper.

Chiller, Christopher; Alanson Chiller, Angela; Jasinski, Benjamin; Snyder, Nathan; Mei, Dongming

2013-04-01

75

The setup of an extraction system coupled to a hydrogen isotopes distillation column  

SciTech Connect

Among the most difficult problems of cryogenic distillation one stands apart: the extraction of the heavy fraction. By an optimal design of the cycle scheme, this problem could be avoided. A 'worst case scenario' is usually occurring when the extracted fraction consists of one prevalent isotope such as hydrogen and small amounts of the other two hydrogen isotopes (deuterium and/or tritium). This situation is further complicated by two parameters of the distillation column: the extraction flow rate and the hold-up. The present work proposes the conceptual design of an extraction system associated to the cryogenic distillation column used in hydrogen separation processes. During this process, the heavy fraction (DT, T{sub 2}) is separated, its concentration being the highest at the bottom of the distillation column. From this place the extraction of the gaseous phase can now begin. Being filled with adsorbent, the extraction system is used to temporarily store the heavy fraction. Also the extraction system provides samples for the gas Chromatograph. The research work is focused on the existent pilot plant for tritium and deuterium separation from our institute to validate the experiments carried out until now. (authors)

Zamfirache, M.; Bornea, A.; Stefanescu, I.; Bidica, N.; Balteanu, O.; Bucur, C. [INC-DTCI, ICSIRm. Valcea, Uzinei Street 4, Rm. Valcea (Romania)

2008-07-15

76

Evaluation of columns packed with shell particles with compounds of pharmaceutical interest  

Microsoft Academic Search

The commercial C18 columns packed with sub-3?m shell particles were tested and compared to a reference UHPLC column, in terms of kinetic performance as well as selectivity, retention capability, peak shape and loading capacity. For this purpose, a set of pharmaceutically relevant molecules was selected, including acidic, neutral and basic drugs. Regarding kinetic performance, hopt values for the shell particles

Joséphine Ruta; Daria Zurlino; Candice Grivel; Sabine Heinisch; Jean-Luc Veuthey; Davy Guillarme

77

Implementation of Ethanol Dehydration Using Dividing-Wall Heterogeneous Azeotropic Distillation Column  

Microsoft Academic Search

In this article, the design and optimization procedures of a dividing-wall column for heterogeneous azeotropic distillation (DWC-A) using cyclohexane as an entrainer for ethanol dehydration are investigated. The proposed procedures can detect the optimal values of the design variables and thereby guarantee the minimum energy requirements, which is related to the minimum CO2 emissions and the lowest total annual cost

Lan-Yi Sun; Xing-Wu Chang; Cai-Xia Qi; Qing-Song Li

2011-01-01

78

Development of chromatofocusing techniques employing mixed-mode column packings for protein separations.  

PubMed

Recent studies reported in the literature using mixed-mode chromatography (MMC) column packings have shown that multiple modes of interactions between the column packing and proteins can be usefully exploited to yield excellent resolution as well as salt-tolerant adsorption of the target protein. In this study, a mixed-mode separation method using commercially available column packings was explored which combines the techniques of hydrophobic-interaction chromatography and chromatofocusing. Two different column packings, one based on mercapto-ethyl-pyridine (MEP) and the other based on hexylamine (HEA) were investigated with regard to their ability to separate proteins when using internally generated, retained pH gradients. The effects of added salt and urea on the behavior of the retained pH gradient and the protein separation achieved when using MMC column packings for chromatofocusing were also investigated. Numerical simulations using methods developed in previous work were shown to agree with experimental results when using reasonable physical parameters. These numerical simulations were also shown to be a useful qualitative method to select the compositions of the starting and elution buffers in order to achieve desired shapes for the pH and ionic strength gradients. The use of the method to fractionate blood serum was explored as a prototype example application. PMID:24296295

Guo, Hui; Li, Xiang; Frey, Douglas D

2014-01-01

79

Design and construction of a packed column simulator operating under atmospheric and reduced pressure  

Microsoft Academic Search

Distillation under reduced pressure for the separation of constituants is considered. To avoid thermic damage in columns, the most important parameters are pressure loss and resistance time. The development of a simulator, enabling the determination of the hydrodynamic parameters with the mixture air-water under different pressures for any given mixture, is carried out. A bibliographic study and a reference study,

Abdelhamid Messaoudene

1989-01-01

80

Fluid Dynamics of Packed Columns for Gas\\/Liquid Systems – Summary of Results  

Microsoft Academic Search

\\u000a One the major objectives of this book was to consolidate the extensive research material available on the fluid dynamics of\\u000a packed columns in counter-current two-phase flow and to extend the application range, compared to the first German edition\\u000a of this book. This was possible by deriving some generally valid equations for individual packing-specific parameters, such\\u000a as gas velocity at flooding

Jerzy Ma?kowiak

81

CFD SIMULATION AND EXPERIMENTAL STUDY OF FLOW IN PACKED BUBBLE COLUMNS  

Microsoft Academic Search

The gas holdup in a small-scale packed bubble column with dimensions of 35?mm wide and 10?mm deep was measured for air-water system. The effect of gas flow rate on gas holdup was investigated for various packings such as spheres, Berl saddles, and knitted meshes. In all cases it was found that the gas holdup increases with increasing gas flow rate.

F. H. YIN; J. L. MIDGLEY; A. AFACAN; K. NANDAKUMAR; K. T. CHUANG

2004-01-01

82

Investigation of numerical solution approaches to multicomponent batch distillation in packed beds  

SciTech Connect

Finite difference and orthogonal collocation techniques are used to obtain numerical solution of the differential contactor model that represents a packed column. In the orthogonal collocation approach, polynomial approximation to the model equations results in a sparse system of equations that is much smaller in dimension than with the other methods. Exploiting this sparsity and choosing the proper order for approximating polynomial are the critical issues. Higher CPU time associated with higher order of the polynomial necessitates use of finite elements in the collocation techniques. The authors study the accuracy and efficiency issues underlying all these approaches with the help of hydrocarbon mixture and ethanol esterification examples. The later case study is considered with both with and without the presence of reaction.

Wajge, R.M.; Wilson, J.M.; Pekny, J.F.; Reklaitis, G.V. [Purdue Univ., Lafayette, IN (United States). School of Chemical Engineering] [Purdue Univ., Lafayette, IN (United States). School of Chemical Engineering

1997-05-01

83

Liquid distribution and its effect on local mass transfer in a packed column of Pall rings  

Microsoft Academic Search

The spatial variations of liquid distribution and local mass transfer coefficient in a 0.30-m column of 25.4-m Pall rings were investigated. The data of liquid distribution was collected with a 39-cell liquid collector and a wall-flow tube from a doubled-wall section in the column at the packing-support level. The local mass transfer coefficients were measured via the electrochemical technique by

Yongjia Zhu

2005-01-01

84

Influence of liquid redistributors on the mass-transfer efficiency of packed columns  

SciTech Connect

In industrial mass-transfer columns liquid distributors and redistributors are used to mix the liquid after a certain random packing or structured packing height before it is applied to the next bed. The purpose of this is to counter a possible deterioration of the mass-transfer efficiency along the height of the column as a result of wall flow tendency of the liquid or to minimize the deterioration of the mass-transfer efficiency as a consequence of maldistribution of the liquid by the liquid distributor located above. However, when planning industrial columns, this influence on the mass-transfer efficiency can only be quantified with some difficulty which is why empirical standard values are mostly used for maximum bed and packing heights. This analysis shows that the height, after which liquid redistribution should take place, depends on numerous further influencing factors. It becomes evident that uneven irrigation of a packing with liquid over the cross section of the column is also a cause for the decline in the mass-transfer efficiency along the packed bed. The resultant decline in the mass-transfer efficiency is influenced, for instance, by the gas/liquid equilibrium behavior of the mixture that is to be separated, by the L/V flow ratio in the rectification, absorption, and desorption columns, by the type of packing used, and by the number of theoretical stages to be executed. A simulation procedure is shown, with whose assistance these factors influencing the mass-transfer efficiency can be recorded quantitatively.

Schultes, M.

2000-05-01

85

Soft sensor based composition estimation and controller design for an ideal reactive distillation column.  

PubMed

In this research work, the authors have presented the design and implementation of a recurrent neural network (RNN) based inferential state estimation scheme for an ideal reactive distillation column. Decentralized PI controllers are designed and implemented. The reactive distillation process is controlled by controlling the composition which has been estimated from the available temperature measurements using a type of RNN called Time Delayed Neural Network (TDNN). The performance of the RNN based state estimation scheme under both open loop and closed loop have been compared with a standard Extended Kalman filter (EKF) and a Feed forward Neural Network (FNN). The online training/correction has been done for both RNN and FNN schemes for every ten minutes whenever new un-trained measurements are available from a conventional composition analyzer. The performance of RNN shows better state estimation capability as compared to other state estimation schemes in terms of qualitative and quantitative performance indices. PMID:20887987

Vijaya Raghavan, S R; Radhakrishnan, T K; Srinivasan, K

2011-01-01

86

Evaluation of columns packed with shell particles with compounds of pharmaceutical interest.  

PubMed

The commercial C18 columns packed with sub-3 ?m shell particles were tested and compared to a reference UHPLC column, in terms of kinetic performance as well as selectivity, retention capability, peak shape and loading capacity. For this purpose, a set of pharmaceutically relevant molecules was selected, including acidic, neutral and basic drugs. Regarding kinetic performance, h(opt) values for the shell particles were found between 1.7 and 2, while the UHPLC column provided a value of approximately 2.5. However, this impressive performance should be considered with caution, particularly for the construction of kinetic plots since h(opt) values were sometimes related to the column dimensions, depending on the provider (h(opt) comprised between 1.8 and 2.6 for longer columns of 150 mm packed with shell particles). Despite the non-porous inner core of the shell particles representing between 25 and 36% of the particle, we demonstrated that the decrease in retention was on the maximum equal to 15% for Ascentis column while Acquity and Poroshell were strictly equivalent in terms of retention. Concerning loading capacity, it remains comparable to that of fully porous sub-2 ?m particles and always more pronounced with 0.1% formic acid vs. phosphate buffer. The loading capacity of the different columns was found to be better correlated to the pore volume or surface coverage than the shell thickness. Experimentally, the most pronounced overloading was observed with the Poroshell. Finally, the selectivity and peak shape were evaluated using a mixture of basic and acidic drugs. It appears that results were very similar between sub-3 ?m shell particles and fully porous sub-2-?m particles for our mixture of compounds, showing the ability to transfer existing methods to shell particles, with only limited adjustments. This study confirms the potential of columns packed with shell particles and demonstrates the interest of such column technology with pharmaceutical compounds. PMID:21945196

Ruta, Joséphine; Zurlino, Daria; Grivel, Candice; Heinisch, Sabine; Veuthey, Jean-Luc; Guillarme, Davy

2012-03-01

87

Liquid holdup distribution in packed columns: gamma ray tomography and CFD simulation  

Microsoft Academic Search

In the present study, the liquid (water) holdup distribution was measured in a large scale packed column (0.6 m diameter) filled with 25.4 mm metal Pall rings using noninvasive gamma ray tomography technique. Horizontal scans, at two vertical positions (400 mm apart), were made for two liquid flow rates. Three different designs of liquid distributor were used to examine the

Fuhe Yin; Artin Afacan; K Nandakumar; Karl T Chuang

2002-01-01

88

HYDRODYNAMICS OF A NONAQUEOUS SYSTEM IN A PACKED LIQUID EXTRACTION COLUMN  

Microsoft Academic Search

Dispersed phase holdup, flood point and droplet size data have been obtained for the effectively non-aqueous system Sulfolane-heptane in a 75 mm diameter column packed with random Raschig rings. The holdup results showed distinctly different behaviour from that of aqueous systems, giving a characteristic velocity plot that was concave upwards, indicating an increasing droplet velocity at higher holdup values. The

Richard J. Moore; H. R. Clive Pratt; Geoffrey W. Stevens

1989-01-01

89

Flooding and Mass Transfer in Goodloe-Packed Columns, Part 2.  

National Technical Information Service (NTIS)

Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20 exp 0 C and about 20 atm pressure. ...

J. S. Ayala B. W. Brian A. C. Sharon

1977-01-01

90

A LIQUID FILM MODEL OF TETRAKAIDECAHEDRAL PACKING TO ACCOUNT FOR THE ESTABLISHMENT OF EPIDERMAL CELL COLUMNS  

Microsoft Academic Search

The possibility that the organization of cells into columns in the mammalian epidermis may be a result of the close packing of these cells has been investigated in a model system involving the association of randomly produced soap bubbles into a stable truth. Upon floating to the surface of a liquid, soap bubbles have been found to spontaneously assemble into

David N. Menton

1976-01-01

91

Distillation  

NSDL National Science Digital Library

Science in its earliest beginnings consisted of a practice called alchemy. Alchemy includes the study of chemistry, biology, astronomy, spirituality, physics, and art. Distillation or experiments in purification of substances may have been a part of the practice of alchemy.

N/A N/A (None;)

2005-12-24

92

A macroscopic model for countercurrent gas-liquid flow in packed columns  

SciTech Connect

A macroscopic model based on the volume-averaged equations of motion is presented for countercurrent gas-liquid flow in a packed bed. The model yields a column-limited flooding point as the loss of existence of uniform states. It correctly predicts the existence of two uniform states below the flooding point. The lower branch corresponds to the trends commonly observed experimentally. It is shown that the upper branch is made unattainable by the gas distributor/support plate at the bottom of the column. The occurrence of premature flooding induced by the support plate is also explained. It is suggested that the occurrence of spontaneous liquid segregation, necessitating frequent liquid redistribution in columns with large dumped packings and porosities, is a consequence of the loss of stability of the uniform state in the lower branch.

Dankworth, D.C.; Sundaresan, S. (Dept. of Chemical Engineering, Princeton Univ., Princeton, NJ (US))

1989-08-01

93

The mass transfer kinetics in columns packed with Halo-ES shell particles.  

PubMed

The average mesopore size of the new Halo-ES-Peptide shell particles is 160 Å, markedly larger than that of the classical Halo shell particles (90 Å). We found that this change causes a considerable decrease of the film mass transfer resistance measured for columns packed with these particles. We analyze data obtained by systematic measurements of the C term of the van Deemter equation for the peptide ?-lipotropin (MW = 769 Da), the protein insulin (MW = 5800 Da), and a series of non-retained polystyrene standards (MW = 6400 and 13,200). The improvement in column performance is explained by an increase of the fraction of the external surface area of the shell that allows the entrance of the sample molecules inside the particle. The fraction of the shell surface accessible to a probe controls the rate of its external film mass transfer, i.e. its rate of transfer between the interstitial and the stagnant eluent. Although measurable, the increase in sample diffusivity through the porous shells does not account for the better performance of Halo-ES-peptide columns. Furthermore, the analysis of the HETPs data of small molecules (uracil, acetophenone, toluene, and naphthalene, MW< 150) reveals that the eddy diffusion (A) term of these new columns is 25% lower than that of the classical Halo columns. This result is consistent with the impact of intra-particle diffusivity on the eddy diffusion mechanism in packed columns. As shell diffusivity increases, so does the rate of transfer of sample molecules between the eluent stream-paths flowing through the packed particles and across the column diameter. Dispersion through short-range inter-channel and trans-column eddies is reduced. PMID:21236440

Gritti, Fabrice; Guiochon, Georges

2011-02-18

94

Comparison of Open Tubular Cadmium Reactor and Packed Cadmium Column in Automated Gas-Segmented Continuous Flow Nitrate Analysis  

Microsoft Academic Search

Detailed procedures are provided for preparing packed cadmium columns to reduce nitrate to nitrite. Experiments demonstrated the importance of conditioning both open tubular cadmium reactor (OTCR) and packed copper-coated cadmium columns to achieve 100% reduction efficiency. The effects of segmentation bubbles in the OTCR upon reduction efficiency and baseline noise in nitrate analysis are investigated using an auto-analyzer. Metal particles

Jia-Zhong Zhang; Charles J. Fischer; Peter B. Ortner

2000-01-01

95

A liquid film model of tetrakaidecahedral packing to account for the establishment of epidermal cell columns.  

PubMed

The possiblity that the organization of cells into columns in the mammalian epidermis may be a result of the close packing of these cells has been investigated in a model system involving the association of randomly produced soap bubbles into a stable froth. Upon floating to the surface of a liquid, soap bubbles have been found to spontaneously assemble into precise columns of interdigitating bubbles. The tetrakaidecahedral shape and the spatial configuration of these bubbles closely resemble those of stacked epidermal cells, although the columns of a froth were oriented at a 60degrees angle to their substratum rather than at right angles as occurs in the epidermal cell columns. These observations lend support to the theory that the organization of the cells in the epidermis into columns is due to the assumption of the keratocytes of a minimum surface-close packing array. Such an organizing mechanism would be independent of both positional control of the underlying mitoses and active guidance of the cells as they become superficially displaced within the epidermis. The observation that a high rate of cell turnover is incompatible with the epidermal column structure may be related to the finding that rapidly produced soap bubbles do not, at least initially, assemble into a columnar array. PMID:1270835

Menton, D N

1976-05-01

96

Final Report - Advanced Hydraulic and Mass Transfer Models for Distillation Column Optimization and Design  

SciTech Connect

The project successfully developed a computational fluid dynamics (CFD) based simulation of the hydrodynamics of flow in a commercial structured packing element. This result fulfilled the prime objective of the research program. The simulation utilized commercial CFD code marketed by Fluent Inc. in combination with a novel graphical interface developed by Oak Ridge National Lab. The end product will allow the design of next generation column internals without the need for extensive experimental validation and will expand the fundamental understanding of the vapor-liquid contacting process.

Eldridge, Robert, B.

2005-10-13

97

Evaluation of fructooligosaccharides separation using a fixed-bed column packed with activated charcoal.  

PubMed

Recent studies have shown that the chromatographic separation of mixtures of saccharides may be improved by making use of activated charcoal, a promising low cost material for the separation of sugars, including fructooligosaccharides. In this work, the development of a methodology to separate fructooligosaccharides from glucose, fructose and sucrose, using a fixed bed column packed with activated charcoal is proposed. The influence of temperature, eluant concentration and step gradients were evaluated to increase the separation efficiency and fructooligosaccharide purity. The final degree of fructooligosaccharide purification and separation efficiency were about 94% and 3.03 respectively, using ethanol gradient concentration ranging from 3.5% to 15% (v/v) at 40°C. The fixed bed column packed with the activated charcoal was shown to be a promising alternative for sugar separation, mainly those rich in fructooligosaccharides, leading to solutions of acceptable degrees of purification. PMID:24583465

Kuhn, Raquel Cristine; Mazutti, Marcio A; Albertini, Lilian Buoro; Filho, Francisco Maugeri

2014-05-25

98

Chromatographic Lithium Isotope Separation Using Cubic Antimonic Acid as Column?Packing Material  

Microsoft Academic Search

Ion?exchange chromatographic lithium isotope separation was performed by using granular cubic antimonic acid as column packing material at 50°C. While the single?stage separation factor for the lithium isotopes was 1.0020, independent of the flow rate, HETP was a monotonously increasing function of flow rate both in breakthrough and reverse breakthrough experiments. After 442 cm chromatographic development, the Li atomic fraction increased

Takao Oi; Shinko Takahashi

2005-01-01

99

Biosorption of Cu in a packed bed column by almond shell: optimization of process variables  

Microsoft Academic Search

This paper presents the ability of a low-cost biosorbent, almond shell, to remove Cu(II) ions from aqueous solution. Biosorption capacity of almond shell to removal Cu(II) was studied in a packed bed column. The effect of various parameters, flow rate, initial copper concentration, and mass of biosorbent, was analyzed. A 2 factorial experiment design was carried out to optimize some

Mónica Calero de Hoces; Gabriel Blázquez García; Alicia Ronda Gálvez; Ana Estefanía Álvarez; María Ángeles Martín-Lara

2012-01-01

100

A comprehensive model for the pressure drop in vertical pipes and packed columns  

Microsoft Academic Search

A macroscopic approach is used to describe the hydrodynamics of a two-phase annular counter-current flow in inclined flow channels. This type of flow is characteristic for gas–liquid contact equipment as applied in packed columns. In this study, a distinction is made between the pressure drop caused by the geometry of the channels and the pressure drop caused by the friction

Geert F. Woerlee; Joop Berends; Zarko Olujic; Jan de Graauw

2001-01-01

101

A macroscopic model for countercurrent gas-liquid flow in packed columns  

Microsoft Academic Search

A macroscopic model based on the volume-averaged equations of motion is presented for countercurrent gas-liquid flow in a packed bed. The model yields a column-limited flooding point as the loss of existence of uniform states. It correctly predicts the existence of two uniform states below the flooding point. The lower branch corresponds to the trends commonly observed experimentally. It is

David C. Dankworth; S. Sundaresan

1989-01-01

102

Transport of Viruses Through Saturated and Unsaturated Columns Packed With Sand  

Microsoft Academic Search

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos [2000] to quantify the processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to

R. Anders; C. V. Chrysikopoulos

2008-01-01

103

Transport of Viruses Through Saturated and Unsaturated Columns Packed with Sand  

Microsoft Academic Search

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions.\\u000a The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173–179, 2000) that accounts\\u000a for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous

Robert Anders; Constantinos V. Chrysikopoulos

2009-01-01

104

Chromate transport through columns packed with surfactant-modified zeolite\\/zero valent iron pellets  

Microsoft Academic Search

Chromate transport through columns packed with zeolite\\/zero valent iron (Z\\/ZVI) pellets, either untreated or treated with the cationic surfactant hexadecyltrimethylammonium (HDTMA), was studied at different flow rates. In the presence of sorbed HDTMA, the chromate retardation factor increased by a factor of five and the pseudo first-order rate constant for chromate reduction increased by 1.5–5 times. The increase in rate

Zhaohui Li; H. Kirk Jones; Pengfei Zhang; Robert S. Bowman

2007-01-01

105

Effect of the thermal environment on the efficiency of packed columns in supercritical fluid chromatography.  

PubMed

When a packed column is operated at temperatures and pressures near the critical point in supercritical fluid chromatography, the thermal environment in which it is placed has a significant impact on retention and efficiency. We measured the retention factors, plate heights, and related parameters for elution of a test mixture of alkylbenzenes with 5% methanol/95% carbon dioxide mobile phase on a 250 mm × 4.6 mm i.d. column packed with 5-micron Luna-C18 particles. Separations were performed at outlet pressures from 100 to 150 bar and a column oven temperature of 323K. For a bare column thermostated with convective air, significant efficiency losses were observed for outlet pressures equal to or less than 120 bar. These large efficiency losses are attributed to radial temperature gradients. Addition of foam insulation resulted in significant improvements in efficiency. Operating the column in still air using a commercially available column heater provided the best overall performance, with no measurable efficiency loss over the entire range of pressures studied. A reduced plate height of 1.88 was obtained at an optimum flow rate of 3.0 mL/min at 100 bar outlet pressure and with the temperature of the incoming mobile phase set approximately 2.3K above the temperature of the column oven. Retention time repeatability for all three thermal conditions was equal to or less than 0.5% RSD. These results demonstrate that it is possible to perform fast, efficient separations with excellent repeatability using SFC under near-critical conditions if the thermal environment is optimized to minimize the generation of radial temperature gradients. PMID:23107122

Zauner, Jordan; Lusk, Ryan; Koski, Steven; Poe, Donald P

2012-11-30

106

PRECISION AND ACCURACY IN THE DETERMINATION OF ORGANICS IN WATER BY FUSED SILICA CAPILLARY COLUMN GAS CHROMOTOGRAPHY/MASS SPECTROMETRY AND PACKED COLUMN GAS CHROMATOGRAPHY/MASS SPECTROMETRY  

EPA Science Inventory

Two general methods for the identification and measurement of organic compounds in water are compared. One method employs packed column chromatography and the other fused silica capillary column chromatography. The two gas chromatography/mass spectrometry (GC/MS) methods use diff...

107

Micro-fabricated semi-packed column for gas chromatography by using functionalized parylene as a stationary phase  

NASA Astrophysics Data System (ADS)

The conformal coating of effective stationary phases onto micro-fabricated columns having complex geometries such as semi-packed columns poses a real challenge. Here, we report for the first time the conformal coating of a semi-packed column with amino-functionalized parylene diX-AM (poly-aminomethyl-[2,2]-paracyclophane), which was found to be an effective stationary-phase material for the chromatography of short-retention-time compounds. A semi-packed column (consisting of a zigzag array of 30 µm square micro-pillars in a 1.0 m long, 180 µm wide and 230 µm deep channel) and an open tubular column (1.0 m long, 160 µm wide and 230 µm deep channel) used for comparison purposes were micro-fabricated on silicon that was subsequently coated with diX-AM parylene and thermally bonded. The chromatograms recorded on a commercial gas chromatograph demonstrated the usefulness of the conformal diX-AM coating as a stationary phase for semi-packed columns. The separation efficiency of the semi-packed column was found to be more than ten times that of the open tubular column.

Nakai, T.; Nishiyama, S.; Shuzo, M.; Delaunay, J.-J.; Yamada, I.

2009-06-01

108

Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column.  

PubMed

This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l(-1) loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l(-1) of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging. PMID:19493617

Gokhale, S V; Jyoti, K K; Lele, S S

2009-10-30

109

Modified equilibrium-dispersive model for the interpretation of the efficiency of columns packed on core-shell particle  

SciTech Connect

A modified Equilibrium Dispersive (ED) Model is proposed for the modeling of chromatographic processes in columns packed with shell-particle adsorbents and operated under very high pressures. This new model was validated on the basis of experimental results obtained with 2.1 mm x 150 mm columns packed with superficially porous 1.7 {micro}m Kinetex-C{sub 18} particles and with classical columns packed with 1.7 {micro}m BEH-C{sub 18} fully porous particles. The influence of the heat friction on the performance of these columns was analyzed by comparing the experimental and calculated peak profiles. Moreover a theoretical analysis of the influence the solid-core conductivity on the column efficiency was discussed.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2011-01-01

110

Simple capillary flow porometer for characterization of capillary columns containing packed and monolithic beds.  

PubMed

A simple capillary flow porometer (CFP) was assembled for through-pore structure characterization of monolithic capillary liquid chromatography columns in their original chromatographic forms. Determination of differential pressures and flow rates through dry and wet short capillary segments provided necessary information to determine the mean diameters and size distributions of the through-pores. The mean through-pore diameters of three capillary columns packed with 3, 5, and 7 ?m spherical silica particles were determined to be 0.5, 1.0 and 1.4 ?m, with distributions ranging from 0.1 to 0.7, 0.3 to 1.1 and 0.4 to 2.6 ?m, respectively. Similarly, the mean through-pore diameters and size distributions of silica monoliths fabricated via phase separation by polymerization of tetramethoxysilane (TMOS) in the presence of poly(ethylene glycol) (PEG) verified that a greater number of through-pores with small diameters were prepared in columns with higher PEG content in the prepolymer mixture. The CFP system was also used to study the effects of column inner diameter and length on through-pore properties of polymeric monolithic columns. Typical monoliths based on butyl methacrylate (BMA) and poly(ethylene glycol) diacrylate (PEGDA) in capillary columns with different inner diameters (i.e., 50-250 ?m) and lengths (i.e., 1.5-3.0 cm) were characterized. The results indicate that varying the inner diameter and/or the length of the column had little effect on the through-pore properties. Therefore, the through-pores are highly interconnected and their determination by CFP is independent of capillary length. PMID:20810116

Fang, Yan; Tolley, H Dennis; Lee, Milton L

2010-10-01

111

Transport of Viruses Through Saturated and Unsaturated Columns Packed With Sand  

NASA Astrophysics Data System (ADS)

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos [2000] to quantify the processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media.

Anders, R.; Chrysikopoulos, C. V.

2008-05-01

112

Mass transfer mechanism in liquid chromatography columns packed with shell particles: would there be an optimum shell structure?  

PubMed

The mass transfer mechanisms in columns packed with old (55 ?m Zipax and 5 ?m Poroshell) and recently commercialized shell particles (2.7 ?m Halo-C(18) and Kinetex-C(18)) were investigated from a physico-chemical point of view. Combining a model of diffusion in heterogeneous packed beds (effective medium theory) with values of the heights equivalent to a theoretical plate (HETPs derived from the first and second central moments of the elution profiles) and of the peak variances provided by the peak parking method, we demonstrate that columns packed with current shell particles perform better than those packed with fully porous particles in resolving low molecular weight compounds because the eddy diffusion term of the van Deemter equation of the former is markedly smaller. The calculation of eddy diffusion in column beds suggests that the smaller A terms are due to smaller trans-column velocity bias in columns packed with shell particles. We also show that the mass transfer of large molecules (e.g., proteins) is faster when the internal volume accessible to the analyte increases. Therefore, it is suggested that shell particles made of concentric layers with average pore sizes increasing with increasing diameter would provide columns with higher efficiency. PMID:21081233

Gritti, Fabrice; Guiochon, Georges

2010-12-24

113

Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns  

NASA Technical Reports Server (NTRS)

This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

2001-01-01

114

Packed-column supercritical fluid chromatography/mass spectrometry via a two-stage momentum separator.  

PubMed

The practical utility of a two-stage momentum separator for combining packed-column supercritical fluid chromatography (SFC) with mass spectrometry (MS) is described. A Hewlett-Packard model 1084B liquid chromatograph modified for packed-column SFC is connected to a linear fused-silica capillary restrictor housed in a heated probe held at 60 degrees at the terminus. A makeup of coaxial helium gas (1.5 L/min) or dissolved solvent (0.2-0.4 mL/min) can be introduced at the point of supercritical fluid expansion. The latter SFC effluent (0.3-2.0 mL/min) is expanded into a heated (44 degrees) desolvation chamber and directed through a nozzle positioned at the entrance of a two-stage momentum separator. Enrichment of the analyte relative to the volatile gases allows the transfer of sample particles to the MS ion source to produce electron ionization of flash-volatilized eluates. On-line SFC/MS separation and detection of low microgram levels of involatile, thermally labile analytes in synthetic mixtures is accomplished. Identification of an unknown compound in a drug tampering incident and the identification of an unknown metabolite isolated from horse urine is also accomplished. PMID:2738147

Edlund, P O; Henion, J D

1989-06-01

115

Model for the prediction of liquid phase mass transfer of random packed columns for gas–liquid systems  

Microsoft Academic Search

The following work presents a new, generally applicable model for description of the mass transfer in the liquid phase for packed columns filled with random dumped non-perforated and lattice-type packing with size between 12 and 90mm for gas–liquid systems in operating range up to flooding point.The new equation for evaluation of the volumetric mass transfer coefficient in the liquid phase

Jerzy Ma?kowiak

2011-01-01

116

Permeability Change of Crystalline Silicate Mineral-Packed Bed Column by Highly Alkaline Plume  

SciTech Connect

For the construction of the geological disposal system, the use of the cementitious material may change the permeability of the natural barrier around the repository. Cementitious materials may alter the pH of ground water to highly alkaline. Also, the potential permeability change of the natural barrier is one of the notable factors for performance assessments of geological disposal systems. In the high pH region, the solubility of silica is very high compared to that in the natural pH (around 8). Therefore, highly alkaline groundwater would dissolve and alter a part of rock surface. Usui et al. (2005) reported that the change of mineral pore structure due to chemical reaction is the key factor to consider the change of the permeability [5-6]. Moreover, such a change of the pore structure was considered to be the result of the spatial heterogeneity of chemical composition. Since such spatial heterogeneity exists also in the sedimentary rocks consisting of crystalline minerals such as quartz and feldspar, we need to examine natural rock, in order to obtain more reliable understanding about the change of permeability induced by highly alkaline groundwater (plume). In this study, silica sand as crystalline mineral was packed in the column, and the effect of dissolution induced by the highly alkaline plume on the permeability-change was examined. The silica sand particles mainly consist of SiO{sub 2} and include Al{sub 2}O{sub 3}, FeO, and K{sub 2}O. The volumetric flow rate and the pressure difference between the inlet and outlet of the column were measured, and the permeability was calculated. At the same time, the concentrations of elements in the fluid were measured by ICP-AES. The experimental result showed that permeability decreased gradually, although the silica sand was continuously dissolved in the column. The behavior of the permeability is considered to be the result from the rearrangement of the particles, or precipitation of secondary mineral. In the column test using the silica sand as packed mineral, the flow-path seems to be clogged by the rearrangement of the particles rather than the increase of the pore space between the particles. (authors)

Hideo Usui; Yuichi Niibori; Hitoshi Mimura [Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Aramaki Aza Aoba 6-6-01-2, Aoba-ku, Sendai, 980-8579 (Japan); Osamu Tochiyama [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai, 980-8577 (Japan)

2007-07-01

117

Boron isotope fractionation in liquid chromatography with boron-specific resins as column packing material  

SciTech Connect

Boron-specific resins with n-methyl glucamine as the functional group were used as column packing material of liquid chromatography for boron isotope separation. The shapes of chromatograms in reverse breakthrough experiments were heavily dependent on the pH of the eluents, and there existed a pH value at which a chromatogram of the displacement type was realized nearly ideally. The value of the single-stage separation factor for the boron isotopes varied between 1.010 and 1.022, depending on the temperature and the form of the resins. The existence of the three-coordinate boron species in addition to the four-coordinate species in the resin phase is suggested.

Oi, Takao; Shimazaki, Hiromi; Ishii, Reiko [Sophia Univ., Tokyo (Japan); Hosoe, Morikazu [National Defense Academy, Kanagawa (Japan)

1997-07-01

118

Synthesis of porous polyaromatic column packings for GC analysis of extraterrestrial atmospheres  

NASA Technical Reports Server (NTRS)

The preparation of a polymer for the Pioneer-Venus Large Probe Gas Chromatograph and another polymer for gas-chromatographic analysis of the Jovian atmosphere is described. Technical-grade divinylbenzene is used as a reliable and economical source of monomer for the preparation of polymer beads. The discussion covers monomeric preparation, polymerization apparatus, first-stage polymer beads, second-stage polymer beads, amino-polymer, columns and gas-chromatographic testing instrumentation used. The polymer for the Pioneer-Venus gas chromatograph is also suitable for ammonia but not for amine analysis. However, the polymer for the analysis of the Jovian atmosphere is a chemically derivatized aromatic polymer that is suitable for amine analysis. The two-stage polymerization produces a highly efficient polymer packing clearly superior to others prepared by adjusted dilution of the aqueous-organic suspension system.

Woeller, F. H.; Pollock, G. E.

1978-01-01

119

Acoustically enhanced multicomponent NAPL ganglia dissolution in water saturated packed columns.  

PubMed

The impact of acoustic pressure waves on multicomponent nonaqueous phase liquid (NAPL) ganglia dissolution in water saturated columns packed with glass beads was investigated. Laboratory data from dissolution experiments with two and three component NAPL mixtures suggested that acoustic waves significantly enhance ganglia dissolution due to the imposed oscillatory interstitial water velocity. The dissolution enhancement was shown to be directly proportional to the acoustic wave frequency. Furthermore, it was demonstrated that the greatest dissolution enhancement in the presence of acoustic waves is associated with the component of the NAPL mixture having the smallest equilibrium aqueous solubility. Finally, square shaped acoustic waves were shown to lead to greater NAPL dissolution enhancement compared to sinusoidal and triangular acoustic waves. The results of this study suggested that aquifer remediation using acoustic waves is a promising method particularly for aquifers contaminated with NAPLs containing components with very low equilibrium aqueous solubilities. PMID:15212271

Chrysikopoulos, Constantinos V; Vogler, Eric T

2004-05-15

120

Experimental investigation of acoustically enhanced colloid transport in water-saturated packed columns.  

PubMed

The effects of acoustic wave propagation on the transport of colloids in saturated porous media were investigated by injecting Uranine (conservative tracer) as well as blue and red polystyrene microspheres (colloids of different diameters; 0.10 and 0.028 mum, respectively) into a column packed with glass beads. Experiments were conducted by maintaining the acoustic pressure at the influent at 23.0 kPa with acoustic frequencies ranging from 30 to 150 Hz. The experimental results suggested that colloid size did not affect the forward and reverse attachment rate coefficients. The acoustic pressure caused an increase in the effective interstitial velocity at all frequencies for the conservative tracer and colloids of both sizes, with maximum increase at 30 Hz. Furthermore, acoustics enhanced the dispersion process at all frequencies, with a maximum at 30 Hz. PMID:17240389

Thomas, J Matthew; Chrysikopoulos, Constantinos V

2007-04-01

121

DECOLORIZATION BEHAVIOR OF AZO DYE WITH VARIOUS CO-SUBSTRATE DOSAGES UNDER GRANULAR ACTIVATED CARBON-BIOFILM CONFIGURED PACKED COLUMN OPERATION  

Microsoft Academic Search

The objective of this study was to investigate the decolorization behavior of Acid Orange 7 (AO7) with different dosages of co-substrates under granular activated carbon-biofilm configured packed column (BGAC-packed column) operation. The spent granular activated carbon (GAC) was immobilized with azo dye-degrading microbes through attachment and then the GAC-biofilm was packed into a column. The system was fed with 3

Soon-An Ong; Eiichi Toorisaka; Makoto Hirata; Tadashi Hano

122

Kinetic evaluation of new generation of column packed with 1.3 ?m core-shell particles.  

PubMed

The goal of this study was to critically evaluate a new generation of columns packed with 1.3 ?m core-shell particles. The practical possibilities and limitations of this column technology were assessed and performance was compared with other reference columns packed with 1.7, 2.6 and 5 ?m core-shell particles. The column efficiency achieved with 1.3 ?m core-shell particles was indeed impressive, Hmin value of only 1.95 ?m was achieved, this would correspond to an efficiency of more than 500,000 plates/m. The separation impedance of this column was particularly low, Emin=2000, mostly due to a reduced plate height, h of 1.50. Comparing the kinetic performance of 1.3 ?m core-shell particles to that of other particle dimensions tested in this study revealed that the 1.3 ?m material could provide systematically the shortest analysis time in a range of below 30,000 theoretical plates (N<30,000).Despite its excellent chromatographic performance, it was evident that this column suffers from the limitations of current instrumentation in terms of upper pressure limit and extra-column band broadening: (1) even at 1,200 bar, it was not possible to reach an optimal linear velocity showing minimal plate height value, due to the low permeability of this column (Kv=1.7×10(-11)cm(2)), and (2) for these short narrow bore columns packed with 1.3 ?m core shell particles, which is mandatory for performing fast-analysis and preventing the influence of frictional heat on column performance in UHPLC, it was observed that the extra-column band broadening could have a major impact on the apparent kinetic performance. In the present work, significant plate count loss was noticed for retention factors of less than 5, even with the best system on the market (?(2)ec=2 ?L(2)). PMID:23953620

Fekete, Szabolcs; Guillarme, Davy

2013-09-20

123

COED Transactions, Vol. X, No. 5, May 1978. STAGEF, A Program to Compute the Internal Variables of an Operating Distillation Column.  

ERIC Educational Resources Information Center

A digital computer program, STAGEF, designed for use with the distillation experiments in a typical undergraduate Chemical Engineering laboratory in Unit Operations is explained. The program enables the student to determine the rate of liquid overflow and vapor boil-up which leaves each tray within the distillation column. The student may also…

Marcovitz, Alan B., Ed.

124

Transport of viruses through saturated and unsaturated columns packed with sand  

USGS Publications Warehouse

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173-179, 2000) that accounts for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media. ?? Springer Science+Business Media B.V. 2008.

Anders, R.; Chrysikopoulos, C. V.

2009-01-01

125

Performance of tapered-column packed-bed bioreactor used for ethanol production by immobilized yeast cells  

Microsoft Academic Search

The tapered-column packed-bed bioreactor was tested as a solution to the problems of pressure drop and nonuniform flow in immobilized-yeast fermentations. The column operation was simulated using a mathematical model considering the effects of the heterogeneous kinetics, interfacial mass transfer, convective and dispersive flows of the liquid phase. The kinetics of ethanol production by the immobilized Saccharomyces cerevisiae was determined

Hamamci

1986-01-01

126

Direct injection of aqueous samples in packed column supercritical fluid chromatography of isosorbide-5-mononitrate from drug release testing  

Microsoft Academic Search

A method for the analysis of aqueous samples of isosorbide-5-mononitrate (5-ISMN) is presented. It is based on packed column supercritical fluid chromatography (SFC) using 20% of 2-propanol in carbon dioxide as the mobile phase and a diol silica column as the stationary phase. Using the described conditions it is possible to quantitate 5-ISMN released from Imdur® tablets in gastric media.

Olle Gyllenhaal; Johan Hulthe

2002-01-01

127

Use of a Packed-Column Bioreactor for Isolation of Diverse Protease-Producing Bacteria from Antarctic Soil  

Microsoft Academic Search

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10°C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were

Nathalie Wery; Ursula Gerike; Ajay Sharman; Julian B. Chaudhuri; David W. Hough; Michael J. Danson

2003-01-01

128

Design Data, Liquid Distributors and Condenser for a Distillation Column to Enrich Tritium in Metallic Lithium.  

National Technical Information Service (NTIS)

Tritium, one fuel component of the fusion reactor is bred from the reactors blanket material lithium. Before extracting the tritium from, for instance, metallic lithium by permeation it has to be enriched in the lithium by high temperature distillation. I...

E. Barnert

1984-01-01

129

Fitting adsorption isotherms to the distribution data determined using packed micro-columns for high-performance liquid chromatography.  

PubMed

Knowing the adsorption isotherms of the components of a mixture on the chromatographic system used to separate them is necessary for a better understanding of the separation process and for the optimization of the production rate and costs in preparative high-performance liquid chromatography (HPLC). Currently, adsorption isotherms are usually measured by frontal analysis, using conventional analytical columns. Unfortunately, this approach requires relatively large quantities of pure compounds, and hence is expensive, especially in the case of pure enantiomers. In this work, we investigated the possible use of packed micro-bore and capillary HPLC columns for the determination of adsorption isotherms of benzophenone, o-cresol and phenol in reversed-phase systems and of the enantiomers of mandelic acid on a Teicoplanin chiral stationary phase. We found a reasonable agreement between the isotherm coefficients of the model compounds determined on micro-columns and on conventional analytical columns packed with the same material. Both frontal analysis and perturbation techniques could be used for this determination. The consumption of pure compounds needed to determine the isotherms decreases proportionally to the second power of the decrease in the column inner diameter, i.e. 10 times for a micro-bore column (1 mm I.D.) and 100 times for capillary columns (0.32 mm I.D.) with respect to 3.3 mm I.D. conventional columns. PMID:11519805

Jandera, P; Bunceková, S; Mihlbachler, K; Guiochon, G; Backovská, V; Planeta, J

2001-08-01

130

Feasability of neat carbon dioxide packed column comprehensive two dimensional supercritical fluid chromatography.  

PubMed

The design and implementation of comprehensive two dimensional supercritical fluid chromatography (SFC) using neat carbon dioxide as the mobile phase is described. Two conventional supercritical fluid chromatographs were hyphenated via an on line comprehensive 2D liquid chromatography like interface; it consisted of a two loop switching valve allowing the collection of the first dimension column effluent, the second dimension separation of a fraction being performed during the time allowed for the collection of the subsequent fraction of the first dimension eluent. Both dimension separations were monitored via UV detection; for the second dimension, the main flow was diverted to implement flame ionisation detection for the detection of hydrocarbons and the construction of the corresponding colour plots. Some key parameters related to the interfacing of the two dimensions and the chromatographic conditions used in both dimensions are discussed. In this preliminary report, the feasibility of comprehensive 2D SFC is demonstrated on synthetic mixtures of hydrocarbons and its potential on real sample analysis is illustrated by the separation of coal derived vacuum distillate. PMID:22533910

Guibal, Pierre; Thiébaut, Didier; Sassiat, Patrick; Vial, Jérôme

2012-09-14

131

Removal of arsenic from drinking water by ferric hydroxide microcapsule-loaded alginate beads in packed adsorption column  

Microsoft Academic Search

In this paper we have presented a unique low cost arsenic removal technique using ferric hydroxide microcapsule-loaded alginate beads (FHMCA) as an adsorbent in a continuous packed column. The microencapsulated particles of ferric hydroxide were produced in a spray dryer and subsequently coated with calcium alginate to form spherical beads of about 2 mm diameter. Batch experiments were conducted with

Priyabrata Sarkar; Priyabrata Pal; Dipankar Bhattacharyay; Suchanda Banerjee

2010-01-01

132

COAL GASIFICATION/GAS CLEANUP TEST FACILITY. VOLUME 4. A MATHEMATICAL MODEL OF THE PACKED COLUMN ACID GAS ABSORBER  

EPA Science Inventory

The report describes a mathematical model for adiabatic operation of a packed-column absorber designed to remove acid gases from coal gasification crude product gas. It also gives results of experiments with a small pilot-scale coal gasification/gas cleaning facility designed to ...

133

Performance of tapered column packed-bed bioreactor for ethanol production.  

PubMed

A tapered column type of bioreactor system packed with immobilized Saccharomyces cerevisiae was used to study the bioreactor performance as a function of design and operating variables. The performance of tapered column bioreactor system was found to be better than that of the conventional cylindrical column reactor system for the ethanol fermentation. The new bioreactor design alleviated problems associated with carbon dioxide evolution and provided a significantly better flow pattern for both liquid and gas phases in the bioreactor without local channelling. A mathematical simulation model, which takes into account of the axial convection and dispersion, interphase mass transfer, and apparent kinetic design parameters, was developed. The effect of radial concentration gradients on the bioreactor performance was found to be insignificant. For the reactor system studied, the maximum ethanol productivity obtained was 60 g ethanol/L gel/h, and the maximum glucose assimilation rate was 140 g glucose/L gel/h. One of the most important findings from this study was that the apparent kinetic parameters change at the glucose concentration of 2 g/L This change was found to be due to the changes in yeast physiology and metabolism. The values of V(m) (') and V(m) (') decreased from 0.8 to 0.39 g ethanol/g cell/h and from 97mM to 11mM, respectively. The substrate inhibition constant was estimated as 0.76M and the product inhibition constant was determined as 113 g ethanol/L The degree of product inhibition showed practically a linear relationship with an increasing ethanol concentration. Based on the hydro-dynamic analysis of the bioreactor system, it was found that the Peclet number, N(Pe) was not a strong function of the flow velocity at low flow rates through the bioreactor system, but its value decreased somewhat at an interstitial velocity greater than 0.03 cm/s. The tapered column bioreactor system showed a much better flow pattern of gas and liquid phases within the reactor, thereby providing a more homogeneous distribution of gas-liquid-solid phases in the reactor without any phase separation. PMID:18576549

Hamamci, H; Ryu, D D

1987-06-01

134

Kinetic investigation of narrow-bore columns packed with prototype sub-2 ?m superficially porous particles with various shell thickness.  

PubMed

The recent successful breakthrough of sub-3 ?m shell particles in HPLC has triggered considerable research efforts toward the design of new brands of core-shell particles. We investigated the mass transfer mechanism of a few analytes in narrow-bore columns packed with prototype 1.7 ?m shell particles, made of 1.0, 1.2, and 1.4 ?m solid nonporous cores surrounded by porous shells 350, 250, and 150 nm thick, respectively. Three probe solutes, uracil, naphthalene, and insulin, were chosen to assess the kinetic performance of these columns. Inverse size exclusion chromatography, peak parking experiments, and the numerical integration of the experimental peak profiles were carried out in order to measure the external, internal, and total column porosities, the true bulk diffusion coefficients of these analytes, the height equivalent to a theoretical plate, the longitudinal diffusion term, and the trans-particle mass transfer resistance term. The residual eddy diffusion term was measured by difference. The results show the existence of important trans-column velocity biases (7%) possibly due to the presence of particle multiplets in the slurry mixture used during the packing process. Our results illustrates some of the difficulties encountered by scientists preparing and packing shell particles into narrow-bore columns. PMID:21872253

Gritti, Fabrice; Omamogho, Jesse; Guiochon, Georges

2011-10-01

135

Pressure, temperature and density drops along supercritical fluid chromatography columns. II. Theoretical simulation for neat carbon dioxide and columns packed with 3-?m particles.  

PubMed

When chromatography is carried out with high-density carbon dioxide as the mobile phase, the required pressure gradient along the column is moderate but this mobile phase is highly compressible so, under certain experimental conditions, its density may decrease significantly along the column. Such an expansion absorbs heat and causes cooling of the column. The resulting heat transfer causes the formation of axial and radial gradients of temperature and density that may become large under certain conditions. In the first part of this series the pressure, temperature, and density drops were measured over a wide range of experimental temperature and pressure conditions, along columns packed with 3- and 5-?m particles. These columns were suspended in a circulating air bath and were either bare or covered with foam insulation. The behavior of these columns was discussed with special attention to their thermal heterogeneity. In this part we scrutinize the application of two heat transfer models to predict the pressure, temperature and density drops. One is a two-dimensional model that takes into account the axial and radial variations of the relevant chromatographic parameters along the column. The other, one-dimensional model ignores the radial variations of these parameters. The numerical solutions of the two-dimensional model are in excellent agreement with independent experimental data. The one-dimensional model can also be applied for the analysis of the behavior of supercritical fluid chromatography (SFC) columns away from the critical conditions. PMID:22687711

Kaczmarski, Krzysztof; Poe, Donald P; Tarafder, Abhijit; Guiochon, Georges

2012-08-10

136

Design of a thermally integrated bioethanol-fueled solid oxide fuel cell system integrated with a distillation column  

Microsoft Academic Search

Solid oxide fuel cell systems integrated with a distillation column (SOFC-DIS) have been investigated in this study. The MER (maximum energy recovery) network for SOFC-DIS system under the base conditions (CEtOH=25%, EtOH recovery=80%, V=0.7V, fuel utilization=80%, TSOFC=1200K) yields QCmin=73.4 and QHmin=0kW. To enhance the performance of SOFC-DIS, utilization of internal useful heat sources from within the system (e.g. condenser duty

W. Jamsak; P. L. Douglas; E. Croiset; R. Suwanwarangkul; N. Laosiripojana; S. Charojrochkul; S. Assabumrungrat

2009-01-01

137

Fast and universal HPLC method for determination of permethrin in formulations using 1.8-?m particle-packed column and performance comparison with other column types.  

PubMed

An HPLC method has been developed for the fast separation and quantification of permethrin using C18 column packed with 1.8 µm particles. The method is specific with good resolution to degradation products and to other present components. It has acceptable validation results. The run time is 4.5 min (or may be within 1.6 min is rapid resolution mode) with an organic solvent consumption of 3.6 mL per run. The method has been applied to samples of formulations for various uses: mattress cleaner, shampoo, and veterinary powder. The performance of the applied column is compared with other common column types. The relationships between linear velocity of the mobile phase (u) and resolution factor (Rs), back-pressure (?P), and efficiency (H) are presented. The experimental data shows the advantages of 1.8-µm particle columns to be a significant reduction in solvent consumption (by factor of 4.4 and 1.5) and a reduction in run-time (by factor 4.7 and 1.5), and the weaknesses are a high back-pressure and lower efficiency. Finally, it has been shown that use of 1.8-µm particle packed columns with conventional HPLC systems is possible, but with limitations in mobile phase flow-rate. PMID:22291055

Shishovska, Maja A; Stefova, Marina T

2012-01-01

138

Evaluation of bioemulsifier mediated Microbial Enhanced Oil Recovery using sand pack column.  

PubMed

Bacillus licheniformis K125, isolated from an oil reservoir, produces an effective bioemulsifier. The crude bioemulsifier showed 66% emulsification activity (E(24)) and reduced the surface tension of water from 72 to 34 mN/m. It contains substantial amount of polysaccharide, protein and lipid. This bioemulsifier is pseudoplastic non-Newtonian in nature. It forms oil in water emulsion which remains stable at wide range of pH, temperature and salinity. It gave 43+/-3.3% additional oil recovery upon application to a sand pack column designed to simulate an oil reservoir. This is 13.7% higher than that obtained from crude lipopeptide biosurfactants produced by the standard strain, Bacillus mojavensis JF2 and 8.5% higher than hot water spring isolate, Bacillus licheniformis TT42. The increased oil recovery obtained by using the crude bioemulsifier can be attributed to its combined surface and emulsification activity. Its mechanism of oil recovery must be similar to the mechanism exhibited by surfactant-polymer flooding process of chemical enhanced oil recovery. PMID:18625271

Suthar, Harish; Hingurao, Krushi; Desai, Anjana; Nerurkar, Anuradha

2008-10-01

139

Unsplittable Flow in Paths and Trees and Column-Restricted Packing Integer Programs  

NASA Astrophysics Data System (ADS)

We consider the unsplittable flow problem (UFP) and the closely related column-restricted packing integer programs (CPIPs). In UFP we are given an edge-capacitated graph G = (V,E) and k request pairs R 1, ..., R k , where each R i consists of a source-destination pair (s i ,t i ), a demand d i and a weight w i . The goal is to find a maximum weight subset of requests that can be routed unsplittably in G. Most previous work on UFP has focused on the no-bottleneck case in which the maximum demand of the requests is at most the smallest edge capacity. Inspired by the recent work of Bansal et al. [3] on UFP on a path without the above assumption, we consider UFP on paths as well as trees. We give a simple O(logn) approximation for UFP on trees when all weights are identical; this yields an O(log2 n) approximation for the weighted case. These are the first non-trivial approximations for UFP on trees. We develop an LP relaxation for UFP on paths that has an integrality gap of O(log2 n); previously there was no relaxation with o(n) gap. We also consider UFP in general graphs and CPIPs without the no-bottleneck assumption and obtain new and useful results.

Chekuri, Chandra; Ene, Alina; Korula, Nitish

140

Production of isopropyl palmitate in a catalytic distillation column: Experimental studies  

Microsoft Academic Search

The fatty acid esters produced using monohydric alcohols have a wide range of applications in the cosmetic and personal care products. The conventional method for the production of esters has several drawbacks such as product quality degradation due to relatively long exposure to heat, necessity of catalyst neutralization and relative high alcohol demand. The reactive distillation (RD) process for the

S. Bhatia; A. L. Ahmad; A. R. Mohamed; S. Y. Chin

2006-01-01

141

Comparison of the gradient kinetic performance of silica monolithic capillary columns with columns packed with 3 ?m porous and 2.7 ?m fused-core silica particles.  

PubMed

The kinetic-performance limits of a capillary silica C18 monolithic column and packed capillary columns with fully-porous 3 ?m and fused-core 2.7 ?m silica C18 particles (all 5 cm long) were determined in gradient-elution mode for the separation of peptides. To establish a kinetic plot in gradient-elution mode, the gradient time to column dead time ratio (t(G)/t?) was maintained constant when applying different flow rates. The normalized gradient approach was validated by dimensionless chromatograms, obtained at different flow rates and gradient times by plotting them as a function of the retention factor. The separation performance of the different column types was visualized via kinetic plots depicting the gradient time required to achieve a certain peak capacity when operating at a maximum system pressure of 350 bar. The gradient steepness (applying t(G)/t?=10, 20, and 40) did not significantly affect the gradient performance limits for low (< 250) peak-capacity separations. For high peak-capacity separations the peak capacity per unit time increases when increasing the t(G)/t? ratio. The C-term contribution of the porous 3 ?m and fused-core 2.7 ?m was comparable yielding the same gradient kinetic-performance limits for fast separations at a column temperature of 60 °C. The capillary silica monolithic column showed the lowest contribution in mass transfer and permeability was higher than the packed columns. Hence, the silica monolith showed the best kinetic performance for both fast and high peak-capacity gradient separations. PMID:21855077

Vaast, Axel; Broeckhoven, Ken; Dolman, Sebastiaan; Desmet, Gert; Eeltink, Sebastiaan

2012-03-01

142

Liquid distribution of MEA in random and structured packing in a square column  

Microsoft Academic Search

Liquid flow distribution in a square column was analyzed to evaluate the contact between liquid and gas phases in an absorption column, and to compare the results from a conventional cylindrical column. The square column was 12 inches wide by 12 inches deep by 40 inches tall. It was constructed with glass walls so that the flow pattern could be observed. The liquid

Stephen Marcia; David deMontigny; Paitoon Tontiwachwuthikul

2009-01-01

143

Effect of Gravity on Colloid Transport through Water-Saturated Columns Packed with Glass Beads: Modeling and Experiments.  

PubMed

The role of gravitational force on colloid transport in water-saturated columns packed with glass beads was investigated. Transport experiments were performed with colloids (clays: kaolinite KGa-1b, montmorillonite STx-1b). The packed columns were placed in various orientations (horizontal, vertical, and diagonal) and a steady flow rate of Q = 1.5 mL/min was applied in both up-flow and down-flow modes. All experiments were conducted under electrostatically unfavorable conditions. The experimental data were fitted with a newly developed, analytical, one-dimensional, colloid transport model. The effect of gravity is incorporated in the mathematical model by combining the interstitial velocity (advection) with the settling velocity (gravity effect). The results revealed that flow direction influences colloid transport in porous media. The rate of particle deposition was shown to be greater for up-flow than for down-flow direction, suggesting that gravity was a significant driving force for colloid deposition. PMID:24857560

Chrysikopoulos, Constantinos V; Syngouna, Vasiliki I

2014-06-17

144

Design and simulation of a distillation column for separation of dichloropropane from a multicomponent mixture  

Microsoft Academic Search

In the paper is presented the design of a separation column for recovery of 1,2-dichloropropane (DCP) from the off-gas released during propylenechlorhydrine (PCH) synthesis. The aim of this separation is to recover DCP with a purity of 99.99 mass%. The simulation of the separation column is performed by means of the professional simulation program HYSYS. The design of the rectification

M Šoóš; E Graczová; J Markoš; A Molnár; P Steltenpohl

2003-01-01

145

Practical comparison of LC columns packed with different superficially porous particles for the separation of small molecules and medium size natural products.  

PubMed

Commercial C(18) columns packed with superficially porous particles of different sizes and shell thicknesses (Ascentis Express, Kinetex, and Poroshell 120) or sub-2-?m totally porous particles (Acquity BEH) were systematically compared using a small molecule mixture and a complex natural product mixture as text probes. Significant efficiency loss was observed on 2.1-mm id columns even with a low dispersion ultra-high pressure liquid chromatography system. The Kinetex 4.6-mm id column packed with 2.6-?m particles exhibited the best overall efficiency for small molecule separations and the Poroshell 120 column showed better performance for mid-size natural product analytes. The Kinetex 2.1-mm id column packed with 1.7-?m particles did not deliver the expected performance and the possible reasons besides extra column effect have been proved to be frictional heating effect and poor column packing quality. Different column retentivities and selectivities have been observed on the four C(18) columns of different brands for the natural product separation. Column batch-to-batch variability that has been previously observed on the Ascentis Express column was also observed on the Kinetex and Poroshell 120 column. PMID:21936054

Yang, Peilin; McCabe, Terry; Pursch, Matthias

2011-11-01

146

Pressure, temperature and density drops along supercritical fluid chromatography columns. I. Experimental results for neat carbon dioxide and columns packed with 3- and 5-micron particles.  

PubMed

The pressure drop and temperature drop on columns packed with 3- and 5-micron particles were measured using neat CO(2) at a flow rate of 5 mL/min, at temperatures from 20°C to 100°C, and outlet pressures from 80 to 300 bar. The density drop was calculated based on the temperature and pressure at the column inlet and outlet. The columns were suspended in a circulating air bath either bare or covered with foam insulation. The results show that the pressure drop depends on the outlet pressure, the operating temperature, and the thermal environment. A temperature drop was observed for all conditions studied. The temperature drop was relatively small (less than 3°C) for combinations of low temperature and high pressure. Larger temperature drops and density drops occurred at higher temperatures and low to moderate pressures. Covering the column with thermal insulation resulted in larger temperature drops and corresponding smaller density drops. At 20°C the temperature drop was never more than a few degrees. The largest temperature drops occurred for both columns when insulated at 80°C and 80 bar, reaching a maximum value of 21°C for the 5-micron column, and 26°C for the 3-micron column. For an adiabatic column, the temperature drop depends on the pressure drop, the thermal expansion coefficient, and the density and the heat capacity of the mobile phase fluid, and can be described by a simple mathematical relationship. For a fixed operating temperature and outlet pressure, the temperature drop increases monotonically with the pressure drop. PMID:22521956

Poe, Donald P; Veit, Devon; Ranger, Megan; Kaczmarski, Krzysztof; Tarafder, Abhijit; Guiochon, Georges

2012-08-10

147

Experimental studies of selective acid gas removal: Absorption of hydrogen sulfide and carbon dioxide into aqueous methyldiethanolamine using packed columns  

SciTech Connect

The use of aqueous methyldiethanolamine (MDEA) for selective removal of hydrogen sulfide from acid gas streams has been studied in a 2 inch column packed with 1/4 inch ceramic Intalox saddles. The column was operated in a counter-current, steady state fashion. The feed gas composition varied between 1 and 5 mole % hydrogen sulfide and between 0 and 50 mole % carbon dioxide. In order to assist the development of packed column absorption models, the rate at which pure carbon dioxide absorbs into 2 M MDEA was measured as a function of pressure, liquid flow rate and packed bed length. The importance of end effects was carefully evaluated. In addition, draining and tracer methods were used to estimate the amount of static holdup present in the column. Using classical draining methods, as much as 50 % of the total holdup was found to be static. However, according to the step decrease in tracer method, less than 5 % of the total holdup was static. Since the step decrease in tracer method measures the amount of static holdup present in the bed under irrigated conditions, it seems likely that the draining method provides an unrealistic estimate of static holdup. Thus, although the notion of static holdup may be useful as a means of correlating mass transfer coefficients, the data indicate that very little static holdup exists in the column under irrigated conditions. Hence, in the absence of a mechanistically sound model, the choice of whether to use static holdup or dispersion as a means of accounting for deviations from plug flow in the liquid phase should be made on the basis of computational convenience.

Schubert, C.N.

1988-01-01

148

Experimental Study of Solid - Liquid Mass Transfer in Column with Structured Packing  

Microsoft Academic Search

The structured packing beds are increasingly focusing the attention of industrialists and researchers in chemical engineering. Several of its applications, mainly in the field of chemical processes, imply solid-liquid mass transfer steps in beds of solid particles sandwiched in the structure of packing. The kinetics of mass transfer in this type of heterogeneous systems is scarcely reported in the open

G. Soare; R. Dima; V. Plesu

149

ANN controller for binary distillation column — A Marquardt-Levenberg approach  

Microsoft Academic Search

Artificial neural networks can provide good empirical controllers for complex nonlinear processes, because they are nets of basis functions that are useful for many purposes including process control. It is shown here that how artificial neural networks can design the column controller and demonstrate that the network controller is as good as or better than a fuzzy rule based controller.

Amit Kumar Singh; Barjeev Tyagi; Vishal Kumar

2011-01-01

150

Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.  

PubMed

The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column. PMID:22169190

Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

2012-01-01

151

Modelling of Maldistribution in Structured Packings: From Detail to Column Design.  

National Technical Information Service (NTIS)

The aim of the thesis was to determine the origin and extent of both small scale and large scale maldistribution in corrugated sheet structured packings and to develop a complete predictive model for hydraulic and separation performance of industrial scal...

C. F. Stoter

1993-01-01

152

Dehumidification of Air by Aqueous Lithium Chloride in a Packed Column  

Microsoft Academic Search

A packed bed absorber-stripper system has been designed to dehumidify moist air by contact with aqueous solutions of lithium chloride. The packing material used in the study is 1.6 cm (5\\/8 inch) polypropylene Flexi rings, which have a surface to volume ratio of 342 m\\/m (104 ft\\/ft). The absorber is capable of handling air face velocities from 3362.4 to 6746.4

Tsair-Wang Chung; Tushar K. Ghosh; Anthony L. Hines

1993-01-01

153

Experimental Determination of the Mechanisms Responsible For Acoustically Enhanced Contaminant Transport in Water-Saturated Packed Columns  

NASA Astrophysics Data System (ADS)

Previous studies indicated that low frequency range (30 to 150 Hz) acoustic pressure forcing causes an increase in effective interstitial velocity and dispersion for conservative tracers and colloids in water- saturated packed columns. However, the exact mechanisms that lead to the observed enhanced transport are not fully understood. This study attempts to improve our knowledge in this area. Uranine (conservative tracer) as well as polystyrene microspheres (colloids of various diameters) were injected into a column packed with glass beads, saturated with water. Digital photographs were taken of the column under black light at specified time intervals. In situ concentrations were determined by measurement of the fluorescence of Uranine and microspheres in the photographs using MATLAB's® Image Processing Toolbox. Experiments were conducted by maintaining acoustic pressure of 23.0 kPa at the influent with acoustic frequencies ranging from 30 to 100 Hz. The results suggest a pore-scale process is responsible for the enhanced transport. Additional experiments were conducted at a single acoustic frequency (70 Hz) with an increasing intensity of influent acoustic pressure from 0 kPa (base case) to 23.0 kPa. A threshold acoustic pressure was determined below which the enhancement process is not observed.

Thomas, J. M.; Chrysikopoulos, C. V.

2008-12-01

154

Reaction of trace mercury in natural gas with dilute polysulfide solutions in a packed column  

SciTech Connect

This paper reports that the natural gas produced around the world can contain traces of mercury which have to be removed. It is difficult to purify gas to desired mercury levels using conventional techniques. By scrubbing with dilute polysulfide solution, the residual mercury in the gas can be removed from about 0.1 to below 0.01 ppb, a reduction of 90%. In this system, the gas is passed through a packed tower wetted with a solution containing 3 ppm of polysulfide salt. Stainless steel packings are effective for this application. In addition to promoting gas-liquid contact, the stainless steel packings adsorb and concentrate polysulfides which react with Hg in the gas to form insoluble HgS, and thus remove Hg from the gas.

Not Available

1991-12-01

155

Bilirubin removal from human plasma in a packed-bed column system with dye-affinity microbeads  

Microsoft Academic Search

A dye-ligand, Cibacron Blue F3GA, was covalently coupled with the poly(EGDMA-HEMA) microbeads. The affinity sorbent carrying 16.5 ?mol Cibacron Blue F3GA per gram polymer was then used to remove bilirubin from human plasma in a packed-bed column system. Bilirubin adsorption from human plasma on the unmodified poly(EGDMA-HEMA) microbeads was 0.32 mg\\/g, while much higher adsorption values, up to 24.2 mg\\/g,

Adil Denizli; Mustafa Kocakulak; Erhan Pi?kin

1998-01-01

156

Particle-packed column versus silica-based monolithic column for liquid chromatography-electrospray-linear ion trap-tandem mass spectrometry multiallergen trace analysis in foods.  

PubMed

A bicarbonate buffer-based extraction method for the simultaneous analysis of five nut allergens (Ana o 2, cashew-nut; Cor a 9, hazelnut; Pru 1, almond; Ara h3/4, peanut; Jug r 4, walnut) in cereals and biscuits using liquid chromatography-electrospray-linear ion trap-tandem mass spectrometry (LC-ESI-LIT-MS(2)) was developed and validated. The method was based on our earlier published LC-MS(2)-based method in a research frame aimed at the identification and determination of hidden allergens in foods by using selective biomarker peptides. A C18 particle-packed column and a silica-based C18 monolithic column were compared in terms of chromatographic performances, such as peak shape, resolution, analysis time and selectivity. The C18 particle-packed column exhibited better performances and was further used for method development and validation. By operating under MS(2) selected reaction monitoring (SRM) acquisition mode, linearity, limits of detection (LOD) and quantitation, trueness and precision were evaluated on breakfast samples enriched with a mix of the five nuts. Good linearity of the matrix matched-calibration curves was obtained and detection limit values generally varied from 14 to 55 mg nut/kg matrix. Recoveries were in the 76±4% to 94±3% range with RSD <15%. The capabilities of LIT to perform MS(n) fragmentation was exploited to improve selectivity of the analysis, and the LC-(SRM) MS(2) method was compared in terms of LOD, linearity, precision and accuracy with a LC-(SRM) MS(3) method. Finally, both the LC-MS(2) and LC-MS(3) methods were successfully applied to the analysis of nut traces in commercially available breakfast cereals and biscuits. PMID:21030028

Bignardi, Chiara; Elviri, Lisa; Penna, Andrea; Careri, Maria; Mangia, Alessandro

2010-11-26

157

Direct injection of aqueous samples in packed column supercritical fluid chromatography of isosorbide-5-mononitrate from drug release testing.  

PubMed

A method for the analysis of aqueous samples of isosorbide-5-mononitrate (5-ISMN) is presented. It is based on packed column supercritical fluid chromatography (SFC) using 20% of 2-propanol in carbon dioxide as the mobile phase and a diol silica column as the stationary phase. Using the described conditions it is possible to quantitate 5-ISMN released from Imdur tablets in gastric media. The precision upon repeated injections was 2% (RSD) at the 20 microg/ml level (n=8), using peak height measurements, when the solution was circulated through the sample loop of the injector. Samples from drug release testing that had been analyzed with reversed phase LC were analyzed with the present method and the results agreed well. It is also possible to monitor the drug released in a dissolution-testing vessel through direct on-line continuous loading (recirculation) of the sample loop of the SFC instrument. PMID:12062700

Gyllenhaal, Olle; Hulthe, Johan

2002-06-20

158

A capacity model for vertical pipes and packed columns based on entrainment  

Microsoft Academic Search

This study bridges flooding correlations in vertical pipes and packed towers. It is shown that the frictional forces of the gas on the liquid interface can either directly carry the liquid film upwards or induce droplet formation and, therefore, entrainment of the gas phase. A model is presented that estimates the entrainment flood point. The model does not fully explain

Geert F. Woerlee; Joop Berends

2001-01-01

159

Transport and transformation of sulfadiazine in soil columns packed with a silty loam and a loamy sand  

NASA Astrophysics Data System (ADS)

Concerning the transport of the veterinary antibiotic sulfadiazine (SDZ) little is known about its possible degradation during transport. Also its sorption behaviour is not yet completely understood. We investigated the transport of SDZ in soil columns with a special emphasis on the detection of transformation products in the outflow of the soil columns and on modelling of the concentration distribution in the soil columns afterwards. We used disturbed soil columns near saturation, packed with a loamy sand and a silty loam. SDZ was applied as a 0.57 mg L - 1 solution at a constant flow rate of 0.25 cm h - 1 for 68 h. Breakthrough curves (BTC) of SDZ and its transformation products 4-(2-iminopyrimidin-1(2 H)-yl)aniline and 4-hydroxy-SDZ were measured for both soils. For the silty loam we additionally measured a BTC for an unknown transformation product which we only detected in the outflow samples of this soil. After the leaching experiments the 14C-concentration was quantified in different layers of the soil columns. The transformation rates were low with mean SDZ mass fractions in the outflow samples of 95% for the loamy sand compared to 97% for the silty loam. The formation of 4-(2-iminopyrimidin-1(2 H)-yl)aniline appears to be light dependent and did probably not occur in the soils, but afterwards. In the soil columns most of the 14C was found near the soil surface. The BTCs in both soils were described well by a model with one reversible (kinetic) and one irreversible sorption site. Sorption kinetics played a more prominent role than sorption capacity. The prediction of the 14C -concentration profiles was improved by applying two empirical models other than first order to predict irreversible sorption, but also these models were not able to describe the 14C concentration profiles correctly. Irreversible sorption of sulfadiazine still is not well understood.

Unold, M.; Kasteel, R.; Groeneweg, J.; Vereecken, H.

2009-01-01

160

Physical properties and structure of fine core-shell particles used as packing materials for chromatography relationships between particle characteristics and column performance  

SciTech Connect

The recent development of new brands of packing materials made of fine porous-shell particles, e.g., Halo and Kinetex, has brought great improvements in potential column efficiency, demanding considerable progress in the design of chromatographic instruments. Columns packed with Halo and Kinetex particles provide minimum values of their reduced plate heights of nearly 1.5 and 1.2, respectively. These packing materials have physical properties that set them apart from conventional porous particles. The kinetic performance of 4.6 mm I.D. columns packed with these two new materials is analyzed based on the results of a series of nine independent and complementary experiments: low-temperature nitrogen adsorption (LTNA), scanning electron microscopy (SEM), inverse size-exclusion chromatography (ISEC), Coulter counter particle size distributions, pycnometry, height equivalent to a theoretical plate (HETP), peak parking method (PP), total pore blocking method (TPB), and local electrochemical detection across the column exit section (LED). The results of this work establish links between the physical properties of these superficially porous particles and the excellent kinetic performance of columns packed with them. It clarifies the fundamental origin of the difference in the chromatographic performances of the Halo and the Kinetex columns.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2010-01-01

161

A simplified mathematical model of the cryogenic distillation with application to the (13C) isotope separation column  

NASA Astrophysics Data System (ADS)

The isotope (13C) has a widespread application in many fields such as chemistry, physics, medicine, etc. To obtain a high concentration in isotope of interest, in our case (13C), it is used the method of cryogenic distillation of carbon monoxide (CO) which is based on the difference between the vapor pressure of (12C16O) and (13C16O) at the temperature of liquid nitrogen. Isotopic separation plant, used to obtain the isotope (13C), is a complex installation, with many inputs and outputs, rather difficult to control. Due to this reason, from the point of view of automation, it is needed a simplified mathematical model. This model can be determined only with some presumption and simplification assumptions. Using the physical laws, the hydrodynamic part of the process and the mass balance will be described by partial differential equations. In order to design a controller for the column, it is needed a transfer function or a statespace realization of the plant, which is the main contribution of the present work. Implementing this mathematical model will be the key element for describing and understanding the operation of the plant and for future development of process control strategies.

Neaga, A. O.; Festila, C.; Dulf, E. H.; Both, R.; Szelitzky, T.; Gligan, M.

2012-02-01

162

Laboratory studies of the behavior of undissolved solids in both pulsed and packed column extraction systems  

Microsoft Academic Search

A substantial fraction of the finely divided undissolved solid material found in nuclear fuel reprocessing dissolver-product solutions is hydrophobic and tends to ``seek`` any organic-aqueous interface existing within countercurrent liquid-liquid extraction systems. While passing through pulsed-type columns this material is swept out of the aqueous phase by the combined surface area of the tiny bubbles of dispersed phase. Because these

Siemer

2010-01-01

163

Laboratory studies of the behavior of undissolved solids in both pulsed and packed column extraction systems  

Microsoft Academic Search

A substantial fraction of the finely divided undissolved solid material found in nuclear fuel reprocessing dissolver-product solutions is hydrophobic and tends to seek'' any organic-aqueous interface existing within countercurrent liquid-liquid extraction systems. While passing through pulsed-type columns this material is swept out of the aqueous phase by the combined surface area of the tiny bubbles of dispersed phase. Because these

Siemer

1989-01-01

164

Transport of surfactant-facilitated multiwalled carbon nanotube suspensions in columns packed with sized soil particles.  

PubMed

Transport of carbon nanotubes (CNTs) in soil/sediment matrixes can regulate their potential eco-effects and has been however rarely studied. Herein, column experiments were conducted to investigate mobility of CNT suspensions stabilized by dodecylbenzenesulfonic acid sodium salt (SDBS), octyl-phenol-ethoxylate (TX-100) and cetylpyridinium chloride (CPC) in four soil samples with certain particle sizes. Humic acid was extracted from a soil sample and was coated on quartz sands to explore the effect of soil organic matter (SOM) on the mobility. Results showed that the positively-charged CPC-CNT was entirely retained in the columns while the negatively-charged SDBS-CNT and TX-100-CNT more or less broke through the columns. Pearson correlation analyses revealed that soil texture rather than SOM controlled the mobility. Electrostatic attraction to and/or precipitation on the grain surfaces together with the straining effect could explain the CNT retention. These novel results will help to understand the eco-effects of CNTs. PMID:24880534

Lu, Yinying; Yang, Kun; Lin, Daohui

2014-09-01

165

Simultaneous micro steam distillation\\/solvent extraction for the isolation of semivolatile flavor compounds from cinnamon and their separation by series coupled-column gas chromatography  

Microsoft Academic Search

Simultaneous micro steam distillation\\/solvent extraction is an efficient method of extracting semivolatile flavor and fragrance compounds from cinnamon for subsequent separation by series coupled-column gas chromatography. With pentane as the extraction solvent and an extraction time of 1.5 h clean extracts requiring no further sample preparation prior to gas Chromatographic analysis are obtained. It is shown that adulteration of cinnamon

Arya Jayatilaka; Salwa K. Poole; Colin F. Poole; Tina M. P. Chichila

1995-01-01

166

Performance of tapered-column packed-bed bioreactor used for ethanol production by immobilized yeast cells  

SciTech Connect

The tapered-column packed-bed bioreactor was tested as a solution to the problems of pressure drop and nonuniform flow in immobilized-yeast fermentations. The column operation was simulated using a mathematical model considering the effects of the heterogeneous kinetics, interfacial mass transfer, convective and dispersive flows of the liquid phase. The kinetics of ethanol production by the immobilized Saccharomyces cerevisiae was determined using shake-flask batch cultures. It was found that there is a shift in the metabolism of the yeast used at glucose concentrations of about 2 to 5 g/l, and due to this effect two sets of V/sub m/ and K/sub m/ values are determined. Maximum rate of fermentation was found to be 0.80 and 0.39 g ethanol/g cell/hr, and the affinity constant was found to be 97 and 11 mM in the medium and low glucose concentration regions respectively. The rate of fermentation went through a maximum at about 70 g glucose/l and the substrate inhibition constant was found to be 0.76 M. The product inhibition constant was also tested and was found to be 113 g ethanol/l. The column performance was simulated effectively at low residence times and low ethanol concentrations, however at the larger residence times and product concentrations better agreement was obtained by changing the ethanol inhibition constant to 85 g/l. In another set of experiments the effect of inert gas flow and oxygen gas feed into the tapered-column was tested. Inert gas feed helps increase the conversion only at very small flow rates. The effect of oxygen was positive at all the flow rates tested.

Hamamci, H.

1986-01-01

167

Flooding and mass transfer in Goodloe-packed columns. [For Kr absorption in liquid CO in HTGR off-gas systems  

Microsoft Academic Search

Flooding and mass transfer experiments were performed with a CO-air\\/water system to examine mass transfer characteristics in Goodloe-packed columns of 6.4 and 15.2-cm ID for removal of radioactive Kr from HTGR off-gas. The flooding experiments verified previous correlations for the packing. The plug flow model was selected for calculation of the overall mass transfer coefficient, K\\/sub L\\/a. The correlation for

E. I. Chao; R. J. Bertolami; J. L. P. Varlet; G. R. Wilkes

1976-01-01

168

Hypercrosslinked polystyrene as a novel type of high-performance liquid chromatography column packing material. Mechanisms of retention.  

PubMed

An experimental material, Chromalite 5HGN (Purolite, UK), that represents hypercrosslinked polystyrene as a new type of neutral stationary phase for HPLC was examined. The material contains no functional groups, but is compatible with any kind of nonpolar and highly polar mobile phase, and even with water. It is chemically resistant and thermally stable. When using aqueous organic mobile phases, Chromalite 5HGN works similar to standard C18 reversed-phase packings, but is characterized by much greater hydrophobicity and, sometimes, unusual selectivity. When using nonpolar mobile phases, i.e. under "quasi normal-phase" conditions, the retention is mostly governed by the interactions between pi-electronic systems of the adsorbent and adsorbate. Adding highly polar, even hydrophilic solvents into the mobile phase, leads to a shift of retention times toward the "reversed-phase" kind of chromatography, which gives an additional possibility in fine tuning the column selectivity. PMID:12613798

Davankov, V A; Sychov, C S; Ilyin, M M; Sochilina, K O

2003-02-14

169

Use of a Packed-Column Bioreactor for Isolation of Diverse Protease-Producing Bacteria from Antarctic Soil  

PubMed Central

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10°C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were mainly psychrotrophs and presented a high morphological and metabolical diversity. The extracellular protease activities tested were optimal at neutral pH and between 30 and 45°C. 16S ribosomal DNA sequence analyses showed that the bioreactor was colonized by a wide variety of taxons, belonging to various bacterial divisions: ?-, ?-, and ?-Proteobacteria; the Flexibacter-Cytophaga-Bacteroides group; and high G+C gram-positive bacteria and low G+C gram-positive bacteria. Some strains represent candidates for new species of the genera Chryseobacterium and Massilia. This diversity demonstrates that the bioreactor is an efficient enrichment tool compared to traditional isolation strategies.

Wery, Nathalie; Gerike, Ursula; Sharman, Ajay; Chaudhuri, Julian B.; Hough, David W.; Danson, Michael J.

2003-01-01

170

Removal of arsenic from drinking water by ferric hydroxide microcapsule-loaded alginate beads in packed adsorption column.  

PubMed

In this paper we have presented a unique low cost arsenic removal technique using ferric hydroxide microcapsule-loaded alginate beads (FHMCA) as an adsorbent in a continuous packed column. The microencapsulated particles of ferric hydroxide were produced in a spray dryer and subsequently coated with calcium alginate to form spherical beads of about 2 mm diameter. Batch experiments were conducted with these beads to generate isotherm data. The loading capacity was found to be 3.8 mg arsenic/gm of adsorbent. The experimental data conformed to Freundlich adsorption isotherm. A generalized mathematical model was also developed and the visual basic codes run with the physical parameters of the adsorbent and isotherm data that were evaluated experimentally was achieved for a continuous 75 days' operation. The safe disposal of the spent adsorbent was confirmed by the toxicity characteristic leaching procedure (TCLP) results. With known set of physical parameters of the adsorbent, input water flow rate and its arsenic concentration, the model could predict the number of days the column would run with output below a specific arsenic concentration. PMID:20924920

Sarkar, Priyabrata; Pal, Priyabrata; Bhattacharyay, Dipankar; Banerjee, Suchanda

2010-11-01

171

Adsorption performance of packed bed column for nitrate removal using PAN-oxime-nano Fe2O3  

PubMed Central

A continuous fixed bed study was carried out by using PAN-oxime-nano Fe2O3 as a sorbent for the removal of nitrate from aqueous solution. The effect of factors, such as flow rate (2, 5 and 7 mL/min) and bed depth (5, 10 and 15 cm) were studied. Data confirmed that the breakthrough curves were dependent on flow rate and bed depth. The adsoption capacities observed in diffent conditions of flow rates (2,5 and 7 mL/min) were 11.65, 24.38 and 25.89, respectively. Thomas model was applied to experimental data to predict the breakthrough curves using linear regression and to determine the characteristic parameters of the packed bed column. Bed depth/service time analysis (BDST) model was used to investigate the effect of bed depth on breakthrough curves. The results showed that Thomas model was suitable for the normal description of breakthrough curve at the experimental condition. The data were in good agreement with BDST model with R2?>?0.98. Statistical analyses were performed on fluoride removal obtained from different flow rates using SPSS16 software by applying Kruskal- Wallis test. These findings suggested that PAN-oxime-nano Fe2O3 in the column structure presents a great potential in removal of nitrate from aqueous solutions.

2014-01-01

172

Use of a packed-column bioreactor for isolation of diverse protease-producing bacteria from antarctic soil.  

PubMed

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10 degrees C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were mainly psychrotrophs and presented a high morphological and metabolical diversity. The extracellular protease activities tested were optimal at neutral pH and between 30 and 45 degrees C. 16S ribosomal DNA sequence analyses showed that the bioreactor was colonized by a wide variety of taxons, belonging to various bacterial divisions: alpha-, beta-, and gamma-Proteobacteria; the Flexibacter-Cytophaga-Bacteroides group; and high G+C gram-positive bacteria and low G+C gram-positive bacteria. Some strains represent candidates for new species of the genera Chryseobacterium and Massilia. This diversity demonstrates that the bioreactor is an efficient enrichment tool compared to traditional isolation strategies. PMID:12620829

Wery, Nathalie; Gerike, Ursula; Sharman, Ajay; Chaudhuri, Julian B; Hough, David W; Danson, Michael J

2003-03-01

173

Fast chiral separation of drugs using columns packed with sub-2 microm particles and ultra-high pressure.  

PubMed

The use of columns packed with sub-2 microm particles in liquid chromatography with very high pressure conditions (known as UHPLC) was investigated for the fast enantioseparation of drugs. Two different procedures were evaluated and compared using amphetamine derivatives and beta-blockers as model compounds. In one case, cyclodextrins (CD) were directly added to the mobile phase and chiral separations were carried out in less than 5 min. However, this strategy suffered from several drawbacks linked to column lifetime and low chromatographic efficiencies. In the other case, the analysis of enantiomers was carried out after a derivatization procedure using two different reagents, 2,3,4-tri-O-acetyl-alpha-D-arabinopyranosyl isothiocyanate (AITC) and N-alpha-(2,4-dinitro-5-fluorophenyl)-L-alaninamide (Marfey's reagent). Separation of several amphetamine derivatives contained within the same sample was achieved in 2-5 min with high efficiency and selectivity. The proposed approach was also successfully applied to the enantiomeric purity determination of (+)-(S)-amphetamine and (+)-(S)-methamphetamine. Similar results were obtained with beta-blockers, and the separation of 10 enantiomers was carried out in less than 3 min, whereas the individual separation of several beta-blocker enantiomers was performed in 1 min or less. PMID:19544347

Guillarme, Davy; Bonvin, Gregoire; Badoud, Flavia; Schappler, Julie; Rudaz, Serge; Veuthey, Jean-Luc

2010-03-01

174

Packed-column supercritical fluid chromatography for the analysis of isosorbide-5-mononitrate and related compounds in bulk substance and tablets  

Microsoft Academic Search

We describe a packed-column supercritical fluid chromatographic method that can be used for the analysis of isosorbide-5-mononitrate (5-ISMN) bulk substance and the 5-ISMN content of Imdur tablets. The method is based on methanol-modified carbon dioxide as the mobile phase and porous graphitized carbon (PGC, Hypercarb) as column support at 40°C and 100 bar back pressure. The method makes it possible

Olle Gyllenhaal; Anders Karlsson

2000-01-01

175

Evaluation by respirometry of the degradability of retort water using a shale ash and overburden packed column.  

PubMed

Oil shale processing produces an aqueous wastewater stream known as retort water. The fate of the organic content of retort water from the Stuart oil shale project (Gladstone, Queensland) is examined in a proposed packed bed treatment system consisting of a 1:1 mixture of residual shale from the retorting process and mining overburden. The retort water had a neutral pH and an average unfiltered TOC of 2,900 mg 1(-1). The inorganic composition of the retort water was dominated by NH4+. Only 40% of the total organic carbon (TOC) in the retort water was identifiable, and this was dominated by carboxylic acids. In addition to monitoring influent and effluent TOC concentrations, CO2 evolution was monitored on line by continuous measurements of headspace concentrations and air flow rates. The column was run for 64 days before it blocked and was dismantled for analysis. Over 98% of the TOC was removed from the retort water. Respirometry measurements were confounded by CO2 production from inorganic sources. Based on predictions with the chemical equilibrium package PHREEQE, approximately 15% of the total CO2 production arose from the reaction of NH4+ with carbonates. The balance of the CO2 production accounted for at least 80% of the carbon removed from the retort water. Direct measurements of solid organic carbon showed that approximately 20% of the influent carbon was held-up in the top 20cm of the column. Less than 20% of this held-up carbon was present as either biomass or as adsorbed species. Therefore, the column was ultimately blocked by either extracellular polymeric substances or by a sludge that had precipitated out of the retort water. PMID:16128388

Clarke, W P; Ho, N M; Taylor, M; Coombs, S; Bell, P R; Picaro, T

2005-08-01

176

Theoretical and experimental impact of the bed aspect ratio on the axial dispersion coefficient of columns packed with 2.5 ?m particles.  

PubMed

The impact of the ratio of the column diameter to the average particle size (or bed aspect ratio) on the column performance was investigated from theoretical and experimental viewpoints. The experiments were conducted for two series of 100mm long columns, 2.1, 3.0, and 4.6mm in diameter, packed with 2.5 ?m fully porous particles of Bridge Ethylene Hybrid (BEH) for one series and Charged Surface Hybrid (CSH) for the other. The heights equivalent to a theoretical plate (HETP) of two low molecular weight compounds, uracil (non-retained, k=0) and naphthalene (retained, k=2.5), were determined from the true moments of the recorded peak profiles. The results showed a systematic decrease of the column performance for uracil at high flow velocities with decreasing column inner diameter, in agreement with the theoretical predictions of the variation of the trans-column eddy dispersion HETP term with decreasing bed aspect ratio. This result is consistent with the increasing volume fraction of the wall region of the column, in which the average linear velocity of the mobile phase over a distance of 5 particle diameters from the column wall is about 10% larger than in the bulk center of the column (infinite diameter column). For the retained compound, the discrepancies are levelled out due to the longer average residence time and larger particle diffusivities of retained compounds, which allow a more efficient relaxation of the radial concentration gradients. Further improvements of the performance of the larger I.D. columns (3.0 and 4.6mm I.D.) may be achieved by decreasing the harmful effect of this trans-column velocity bias by injecting and/or collecting the sample molecules in a wide central zone of the column. For 2.1mm I.D. columns, this approach would prove useful only when HPLC instruments providing a lower extra-column band broadening contribution will become available. Finally, the further minimization of the trans-column eddy dispersion HETP term and the design of new, better inlet/outlet column endfitting/frit assemblies requires newer and more accurate models of eddy dispersion in packed columns than those previously provided by Gunn and Giddings and the numerical calculation of band profiles using original functions to account for the distribution and collection of the sample molecules at the inlet and outlet of the column. PMID:23010248

Gritti, Fabrice; Guiochon, Georges

2012-11-01

177

Effect of system variables involved in packed column supercritical fluid chromatography of stavudine taken as model analyte using response surface methodology along with study of thermodynamic parameters  

Microsoft Academic Search

A multifactor optimization technique is successfully applied to study the effect of simultaneously varying the system variables on feasibility of stavudine analysis by packed column supercritical fluid chromatography (PC-SFC). The effect of simultaneously varying the pressure, temperature and modifier concentration was studied to optimize the method in order to obtain excellent chromatographic figures of merit. The method is based on

N. Kaul; H. Agrawal; A. R. Paradkar; K. R. Mahadik

2007-01-01

178

Effects of the gas–liquid ratio on the optimum catalyst quantity for the CECE process with a homogeneously packed LPCE column  

Microsoft Academic Search

In order to improve the separative performance of a combined electrolysis catalytic exchange (CECE) process, we have carried out experimental studies on hydrogen isotope separation by a CECE process using a liquid phase catalytic exchange (LPCE) column of trickle-type packed beds. Two types of trickle beds were tested in our previous study. One was the layered bed, where layers of

T. Sugiyama; A. Ushida; I. Yamamoto

2008-01-01

179

Repeatability of the efficiency of columns packed with sub-3?m core-shell particles: Part I. 2.6?m Kinetex-C(18) particles in 4.6mm and 2.1mm×100mm column formats.  

PubMed

The column-to-column repeatability of the mass transfer mechanism in columns packed with sub-3?m shell particles was investigated. The parameters of this mechanism were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.6?m Kinetex-C(18) particles (Phenomenex, CA, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method, the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and a model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is only due to the random nature of the packing process. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 7% and 3% for the low molecular weight compounds and for insulin, respectively. For the 4.6mm I.D. columns, these RSDs were 15% and 5%, respectively. The larger RSDs for the 4.6mm I.D. columns is explained by the exceptionally low value of the eddy diffusion term. PMID:22762953

Gritti, Fabrice; Guiochon, Georges

2012-08-24

180

Speed-resolution properties of columns packed with new 4.6 ?m Kinetex-C(18) core-shell particles.  

PubMed

The achievable separation speed and resolution of columns packed with the new 4.6 ?m Kinetex particles were characterized by their permeability and their plate heights, measured meticulously. Their specific permeabilities range between 1.81 and 1.95 × 10(-10)cm(2) and their external porosities between 0.394 and 0.405. The efficiencies of the eluted peaks measured by numerical integration of the whole band concentration provided minimum reduced plate heights for uracil (non-retained) and naphthalene (retained) between 1.3 and 1.5 (H=6.0-6.9 ?m) for two 4.6 mm × 150 mm replicate columns of Kinetex and between 1.6 and 2.0 (H=7.4-9.2 ?m) for two narrow-bore 2.1 mm × 150 mm replicate columns. The most efficient 4.6 mm × 150 mm Kinetex column shows a deviation of one reduced plate height h unit with respect to the infinite diameter column (no wall, no inlet, no outlet endfitting) at high speed. Eventually, the separation speed and the resolution of columns packed with 4.6 ?m core-shell Kinetex particles are better or equivalent to those of columns packed with 2.5 ?m fully porous particles for hold-up times larger than only 10s. These core-shell materials are virtually equivalent to the second generation of silica monolithic columns with the advantage of operating well at pressure drops larger than 200 bar. PMID:23384789

Gritti, Fabrice; Guiochon, Georges

2013-03-01

181

Analysis of Atmospheric Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Gas\\/Particle Phases Separately Collected by a High-volume Air Sampler Equipped with a Column Packed with XAD-4 Resin  

Microsoft Academic Search

We developed a sampler for collecting atmospheric polycyclic aromatic hydrocarbons (PAHs) and nitropoly- cyclic aromatic hydrocarbons (NPAHs) by attaching a glass column packed with XAD-4 resin to the gas sampling port of a high-volume air sampler equipped with a filter. When the upper and bottom layers of the column were packed with 64 g and 32 g of XAD-4 resin,

Yuki Araki; Ning Tang; Michihiro Ohno; Takayuki Kameda; Akira Toriba; Kazuichi Hayakawaa

2009-01-01

182

Simulation of gas absorption with chemical reaction: The selective removal of hydrogen sulfide by aqueous methyldiethanolamine in packed columns  

SciTech Connect

The design of separation devices, particularly for solvent-based selective removal of H{sub 2}S from CO{sub 2}, requires an accurate mathematical model. Unfortunately, this requirement for high accuracy is often in conflict with the need for efficient computation. The addition of more and more complicated analyses, such as a move from Henry's law to a method incorporating gas and liquid activities for computing vapor liquid equilibria, may give a more accurate solution, but only at the cost of decreased computational efficiency. The efforts in this work have been directed toward two goals. The first was to develop an accurate mathematical model for the aqueous methyldiethanolamine (MDEA) system. The steady-state packed column model developed in this work has been tested with data from Schubert (1988) to verify its accuracy. The second goal was to modify the model to improve its computational efficiency. Areas such as vapor-liquid equilibrium calculations, flow hydrodynamics, and thermal effects were examined to determine what simplifications could be made, and how these simplifications affected both the accuracy and the efficiency of the model. The result of this effort is a mathematical model for multicomponent chemical absorption in a continuous contactor that balances computation efficiency with rigorous physical and chemical treatment. This model is useful not only for the analysis of the MDEA-H{sub 2}S-CO{sub 2} system, but the same framework also could be applied to other chemical absorption systems.

Lindner, J.R.

1988-01-01

183

Quantitative Analysis of Transverse Bacterial Migration Induced by Chemotaxis in a Packed Column with Structured Physical Heterogeneity  

PubMed Central

A two-dimensional mathematical model was developed to simulate transport phenomena of chemotactic bacteria in a sand-packed column designed with structured physical heterogeneity in the presence of a localized chemical source. In contrast to mathematical models in previous research work, in which bacteria were typically treated as immobile colloids, this model incorporated a convective-like chemotaxis term to represent chemotactic migration. Consistency between experimental observation and model prediction supported the assertions that (1) dispersion-induced microbial transfer between adjacent conductive zones occurred at the interface and had little influence on bacterial transport in the bulk flow of the permeable layers and (2) the enhanced transverse bacterial migration in chemotactic experiments relative to nonchemotactic controls was mainly due to directed migration toward the chemical source zone. Based on parameter sensitivity analysis, the results showed that chemotactic parameters determined in bulk aqueous fluid were adequate to predict the microbial transport in our intermediate-scale porous media system. Additionally, the analysis of adsorption coefficient values supported the observation of a previous study that microbial deposition to the surface of porous media might be decreased under the effect of chemoattractant gradients. By quantitatively describing bacterial transport and distribution in a heterogeneous system, this mathematical model serves to advance our understanding of chemotaxis and motility effects in granular media systems and provides insights for modeling microbial transport in in situ microbial processes.

Wang, Meng; Ford, Roseanne M.

2009-01-01

184

Transport of biocolloids in water saturated columns packed with sand: Effect of grain size and pore water velocity.  

PubMed

The main objective of this study was to evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three waterborne fecal indicator organisms (Escherichia coli, MS2, and ?X174) in laboratory-scale columns packed with clean quartz sand. Three different grain sizes and three pore water velocities were examined and the attachment behavior of Escherichia coli, MS2, and ?X174 onto quartz sand was evaluated. The mass recoveries of the biocolloids examined were shown to be highest for Escherichia coli and lowest for MS2. However, no obvious relationships between mass recoveries and water velocity or grain size could be established from the experimental results. The observed mean dispersivity values for each sand grain size were smaller for bacteria than coliphages, but higher for MS2 than ?X174. The single collector removal and collision efficiencies were quantified using the classical colloid filtration theory. Furthermore, theoretical collision efficiencies were estimated only for E. coli by the Interaction-Force-Boundary-Layer, and Maxwell approximations. Better agreement between the experimental and Maxwell theoretical collision efficiencies were observed. PMID:22115094

Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

2011-11-01

185

Conception et Realisation d'UN Simulateur de Colonne Garnie Fonctionnant Sous Pression Atmospherique et Sous Pression Reduite (Design and Construction of a Packed Column Simulator Operating under Atmospheric and Reduced Pressure).  

National Technical Information Service (NTIS)

Distillation under reduced pressure for the separation of constituants is considered. To avoid thermic damage in columns, the most important parameters are pressure loss and resistance time. The development of a simulator, enabling the determination of th...

A. Messaoudene

1989-01-01

186

Fast gradient screening of pharmaceuticals with 5 cm long, narrow bore reversed-phase columns packed with sub-3 ?m core–shell and sub-2 ?m totally porous particles  

Microsoft Academic Search

The performance of 5cm long narrow-bore columns packed with 2.6–2.7?m core–shell particles and a column packed with 1.7?m totally porous particles was compared in very fast gradient separations of polar neutral active pharmaceutical compounds. Peak capacities as a function of flow-rate and gradient time were measured. Peak capacities around 160–170 could be achieved within 25min with these 5cm long columns.

Szabolcs Fekete; Jen? Fekete

2011-01-01

187

Adsorptive removal of fluoride from aqueous medium using a fixed bed column packed with Zr(IV) loaded dried orange juice residue.  

PubMed

The potential of the adsorbent prepared from DOJR marketed as cattle food in Japan was identified as an efficient and low cost adsorbent for fluoride using fixed bed column. DOJR was loaded with Zr(IV) ions to develop active adsorption sites for fluoride. Fluoride adsorption performance of column packed with Zr(IV) loaded DOJR was assessed under variable operating conditions such as Zr(IV) loading temperature, initial fluoride concentration, bed depth, initial pH, and flow rate. Breakthrough curve modeling showed that Thomas and bed depth service time (BDST) models were in good agreement with the experimental data. Application of adsorbent investigated in this study to the treatment of actual waste plating solution containing fluoride ion showed successful removal below acceptable standard in Japan using a fixed bed column, hence, Zr(IV)-DOJR can be expected to be a promising candidate for the treatment waste water containing trace amount of fluoride ion in fixed bed column. PMID:23916190

Paudyal, Hari; Pangeni, Bimala; Inoue, Katsutoshi; Kawakita, Hidetaka; Ohto, Keisuke; Alam, Shafiq

2013-10-01

188

Effect of the Structured Packing on Column Diameter, Pressure Drop and Height in a Mass Transfer Unit  

Microsoft Academic Search

In order to determine the dimension of a separation column, hydrodynamic and mass transfer models are necessary to evaluate the pressure drop and the mass transfer unit height. The present work evaluates the dependency of those parameters with respect to the diameter of the column by means of an absorption column. The process within the absorption column is carried out

Rosa H. Chávez; Javier de J. Guadarrama; Abel Hernández-Guerrero

189

Packed-column capillary electrochromatography and capillary electrochromatography-mass spectrometry using a lithocholic acid stationary phase  

PubMed Central

The preparation and characterization of a novel lithocholic acid (LCA)-based liquid crystalline (LC) stationary phase (SP) suitable for application in packed-column CEC and CEC coupled to MS is described. The extent of bonding reactions of LCA-SP was assessed using 1H-NMR, 13C-NMR and elemental analysis. This characterization is followed by application of the LCA-SP for separation of ?-blockers, phenylethylamines (PEAs), polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Using the optimum mobile phase operating conditions (pH 3.0-4.5, 10 mM ammonium acetate, 85% v/v ACN), a comparison of the chromatographic ability of the aminopropyl silica phase vs. the LCA-bonded phase was conducted. The results showed improved selectivity for all test analytes using the latter phase. For example, the CEC-MS of ?-blockers demonstrated that the LCA-bonded phase provides separation of six out of seven ?-blockers, whereas the amino silica phase provides four peaks of several co-eluting ?-blockers. For the CEC-MS analysis of PEAs, the LCA-bonded phase showed improved resolution and different selectivity as compared to the aminopropyl phase. An evaluation of the retention trends for PEAs on both phases suggested that the PEAs were retained based on varying degree of hydroxyl substitution on the aromatic ring. In addition, the MS characterization shows several PEAs fragment in the electrospray either by loss of an alkyl group and/or by loss of H2O. Finally, the LCA-bonded phase displayed significantly higher separation selectivity for PAHs and PCBs as compared to the amino silica phase.

Norton, Dean; Shamsi, Shahab A.

2009-01-01

190

Modification of the gas-liquid chromatography procedure and evaluation of a new column packing material for the identification of anaerobic bacteria.  

PubMed Central

Gas-liquid chromatography has become a useful aid for the identification of anaerobic bacteria in the clinical laboratory. When many extracted samples are to be analyzed, time is of prime importance. By altering the operating conditions of the chromatograph, we have decreased the total elution time of the volatile fatty acids examined to approximately 12 min. There is, however, a decrease in the ability to resolve propionic and isobutyric acids. A new column packing material, SP-1220 (Supelco), was found to give excellent separation of propionic and isobutyric acids as well as demonstrating the presence of formic acid which was not seen with the previously used Resoflex. Extracts of clinical isolates of anaerobic organisms were processed using the altered conditions and new column packing material with excellent resolution of all acids. The use of SP-1220 in the clinical laboratory will facilitate the identification of anaerobic bacteria.

Hauser, K J; Zabransky, R J

1975-01-01

191

Selective absorption of H 2S from gas mixtures into aqueous solutions of blended amines of methyldiethanolamine and 2-tertiarybutylamino-2-ethoxyethanol in a packed column  

Microsoft Academic Search

In this work, an experimental investigation for selective absorption of H2S from gas-mixed streams into an aqueous blend of methyldiethanolamine (MDEA) and 2-tertiarybutylamino-2-ethoxyethanol (TBEE) in a packed column at atmospheric pressure and a constant liquid flowrate was performed. TBEE, a severe sterically hindered amine, was added into MDEA to form the blended amines. The effect of H2S loading of lean-solution,

Jian-Gang Lu; You-Fei Zheng; Du-Liang He

2006-01-01

192

Calculation procedure to determine average mass transfer coefficients in packed columns from experimental data for ammonia–water absorption refrigeration systems  

Microsoft Academic Search

The ammonia purification process is critical in ammonia–water absorption refrigeration systems. In this paper, a detailed\\u000a and a simplified analytical model are presented to characterize the performance of the ammonia rectification process in packed\\u000a columns. The detailed model is based on mass and energy balances and simultaneous heat and mass transfer equations. The simplified\\u000a model is derived and compared with

Jaime Sieres; José Fernández-Seara

2008-01-01

193

A novel fiber-packed column for on-line preconcentration and speciation analysis of chromium in drinking water with flame atomic absorption spectrometry  

Microsoft Academic Search

A novel on-line preconcentration and determination system based on a fiber-packed column was developed for speciation analysis of Cr in drinking water samples prior to its determination by flame atomic absorption spectrometry (FAAS). All variables involved in the development of the preconcentration method including, pH, eluent type, sample and eluent flow rates, interfering effects, etc., were studied in order to

Romina P. Monasterio; Jorgelina C. Altamirano; Luis D. Martínez; Rodolfo G. Wuilloud

2009-01-01

194

Design of a reactive distillation process for ultra-low sulfur diesel production  

Microsoft Academic Search

The analysis of the applicability of the reactive separation concepts to the deep-hydrodesulfurization process has been performed. Through the computation of the reactive residue curve maps a basic conceptual design of a reactive distillation column was obtained. This preliminary design considers two reactive zones, each one packed with a different catalyst, a Ni?Mo based catalyst for the bottom reactive section

Eduardo S. Perez-Cisneros; Salvador A. Granados-Aguilar; Pedro Huitzil-Melendez; Tomas Viveros-Garcia

2002-01-01

195

Packing for regular distribution of liquid phase over the cross-section of column-type apparatuses  

Microsoft Academic Search

The performance of ceramic honeycomb packing with inclined walls, applied as a distribution layer to be placed under a multi-point liquid distributor with regularly perforated orifices, is studied. The distribution layer must have a good spreading ability without increasing the pressure drop. The aim is to create good liquid distribution over the main honeycomb packing layer with vertical walls. Ten

R Darakchiev; N Kolev; S Nakov

1998-01-01

196

Comparison of performance of high-performance liquid chromatography columns packed with superficially and fully porous 2.5??m particles using kinetic plots.  

PubMed

A recently introduced 2.5??m fully porous support (Kromasil Eternity) is compared with three different brands of superficially porous material (Kinetex, Halo and Poroshell 120) by means of the kinetic plot method using pharmaceutical compounds from GlaxoSmithKline as probe molecules. The kinetic plot method immediately shows the range of plate numbers wherein a support performs better than another. Results from experiments carried out at pH 4.5 and 8.0 are presented in order to assess the pH stability of the tested phases. Moreover, since all supports are able to withstand pressures higher than 400?bar, they have been evaluated both on HPLC and UHPLC instrumentation. True average particle sizes were determined by SEM images taken from loose stationary phases. Kinetex outperforms the other columns in HPLC conditions for practically relevant efficiencies, but shows poor packing quality in the 100×2.1-mm format. Kromasil is advantageous for simple and fast separations on short columns both in HPLC and in UHPLC conditions. Halo achieves the highest efficiencies of all columns at the lowest pressure cost and shows a noticeable lower axial diffusion. Poroshell 120 has the best packing quality reproducibility across the tested formats. All columns preserve their performance at high pH. PMID:21104797

Fanigliulo, Ameriga; Cabooter, Deirdre; Bellazzi, Guido; Tramarin, Davide; Allieri, Brigida; Rottigni, Alessandro; Desmet, Gert

2010-12-01

197

Efficiency for unretained solutes in packed column supercritical fluid chromatography II. Experimental results for elution of methane using large pressure drops.  

PubMed

At near-critical temperatures and pressures, experimental results for elution of methane with neat carbon dioxide on a 150 mm x 2.0 mm I.D. column packed with 5 microm porous silica with a bonded octylsilica stationary phase show much greater efficiency losses than predicted by theory if isothermal conditions are assumed. Experiments with insulated, air- and water-thermostatted columns demonstrate that significant axial and radial temperature gradients are produced by Joule-Thomson cooling of the mobile phase, and that radial temperature gradients can be a major cause of band spreading at low temperatures and pressures. The use of thermal insulation on the column can greatly improve efficiency under these conditions. PMID:16007994

Xu, Wensheng; Peterson, Dawn L; Schroden, Jonathan J; Poe, Donald P

2005-06-17

198

Dealcoholized wines by spinning cone column distillation: phenolic compounds and antioxidant activity measured by the 1,1-diphenyl-2-picrylhydrazyl method.  

PubMed

Spinning cone column (SCC) distillation has been shown to be a commercially suitable technique for dealcoholized wine (DW) manufacturing, but there are not enough studies about its influence on the DW quality. So, the effect of this technique on the antioxidant activity (% of remaining 1,1-diphenyl-2-picrylhydrazyl radical) and the phenolic compound composition of red, rose, and white DW, obtained at pilot plant scale, has been analyzed. Nineteen raw wines (RWs) from different grape varieties and five different Spanish viticultural regions have been studied before and after dealcoholization. The total phenolic content, flavonols, tartaric esters, and anthocyanins, was determined by spectrophotometry, while the content of phenolic compounds such as stilbenes (trans- and cis-resveratrol), flavonols (rutin, quercetin, and myricetin), flavan-3-ols [(+)-catechin and (-)-epicatechin], anthocyanins (malvidin 3-glucoside), and non-flavonoids (gallic, caffeic, and p-coumaric acids) was determined by high-performance liquid chromatography (HPLC). The resveratrol contents in red wines were between 1.81 and 34.01 mg/L in RWs and between 2.12 and 39.57 mg/L in DWs, Merlot being the grape producing the RWs and DWs with higher resveratrol content. In general, the percent of remaining DPPH(*) was similar or slightly higher (until 5 units of % of remaining DPPH(*)) in DWs versus RWs. This small difference may be due to removal of SO2 (that is an antioxidant) from RWs during distillation. DWs and RWs show similar contents of the studied phenolic compounds, with a tendency, in some cases, to exhibit increases after dealcoholization, caused by the concentration effect via removal of the ethanol. From this work, we can deduce that SCC distillation is a dealcoholization technique minimally destructive with the wine phenolic compounds. PMID:19588980

Belisario-Sánchez, Yulissa Y; Taboada-Rodríguez, Amaury; Marín-Iniesta, Fulgencio; López-Gómez, Antonio

2009-08-12

199

Preparation of tertiary amyl alcohol in a reactive distillation column. 1: Reaction kinetics, chemical equilibrium, and mass-transfer issues  

SciTech Connect

The hydration of isoamylenes to produce 2-methyl-2-butanol (tert-amyl alcohol, or TAA) is strongly limited by chemical equilibrium to olefin conversions of less than 50%. The general goal of this work was to determine whether reactive distillation would be a valid method to enhance the yield of TAA. The first step was to study the reaction kinetics and chemical equilibrium, using a polymeric acid catalyst (Amberlyst-15). Acetone was identified as a suitable medium to enable single liquid phase operation and also to enhance the reaction rate. It was found that the intraparticle mass-transfer resistance is negligible at temperatures below 70 C. A kinetic expression, based on Langmuir-Hinshelwood formalism, is proposed. The forward and reverse reactions show first-order dependence on isoamylenes and TAA, respectively, while water is essentially an inhibitor of the reaction in both directions. The temperature effect on the forward reaction is quantified with an activation energy of 69.5 kJ/mol.

Gonzalez, J.C.; Fair, J.R. [Univ. of Texas, Austin, TX (United States). Separations Research Program] [Univ. of Texas, Austin, TX (United States). Separations Research Program

1997-09-01

200

Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and Sol-Gel alumina  

Microsoft Academic Search

The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route, alumina coated with silicon oxide and alumina prepared by Internal Gelation Process (IGP), were used as packing material to study the separation of HT and T2 in a mixture at

Y. P. Naik; N. K. Gupta; K. T. Pillai; G. A. Rama Rao; V. Venugopal

201

Dehumidification of Air by Chemical Liquid Desiccant in a Packed Column and Its Heat and Mass Transfer Effectiveness  

Microsoft Academic Search

The pressure drop, carryover, leak, and corrosion in traditional liquid desiccant dehumidification towers are of serious concern in real applications, especially when using tri ethylene glycol (TEG) as a desiccant. In this study the cellulose rigid media pads are used as the packing for its low pressure drop. A special coated material is used to prevent corrosion and leakage problems.

Esam Elsarrag

2006-01-01

202

Hybrid Sargassum-sand sorbent: a novel adsorbent in packed column to treat metal-bearing wastewaters from inductively coupled plasma-optical emission spectrometry.  

PubMed

Laboratory batch and column experiments were carried out to examine the efficiency of algal-based treatment technique to clean-up wastewaters emanating from inductively coupled plasma-optical emission spectrometry (ICP-OES). Chemical characterization revealed the extreme complexity of the wastewater, with the presence of 14 different metals under very low pH (pH = 1.1), high conductivity (6.98 mS/cm), total dissolved solid (4.46 g/L) and salinity (3.77). Batch experiments using Sargassum biomass indicated that it was possible to attain high removal efficiencies at optimum pH of 4.0. Efforts were also made to continuously treat ICP-OES wastewater using up-flow packed column. However, swelling of Sargassum biomass leads to stoppage of column. To address the problem, Sargassum was mixed with sand at a ratio of 40: 60 on volume basis. Remarkably, the hybrid Sargassum-sand sorbent showed very high removal efficiency towards multiple metal ions with the column able to operate for 11 h at a flow rate of 10 mL/min. Metal ions such as Cu, Cd, and Pb were only under trace levels in the treated water until 11 h. The results of the treatment process were compared with trade effluent discharge standards. Further the process evaluation and cost analysis were presented. PMID:23947707

Vijayaraghavan, K; Joshi, U M

2013-01-01

203

RECOVERY OF URANIUM HEXAFLUORIDE FROM A PROCESS GAS STREAM BY ABSORPTION DISTILLATION TECHNIQUES EMPLOYING A LIQUID FLUOROCARBON MEDIUM  

Microsoft Academic Search

Complete recovery of uranium hexafluoride from a nitrogen-uranium ; hexafluoride mixture was accomplished with a packed column absorption-; distillation system employing perfluorodimethylcyclohexane, CâFââ, as ; the sorbent. The pilot plant operated well on a continuous basis, and the ; limiting gas and liquid rates agreed well with those predicted from standard ; correlations. For absorption, values of the height of

R. A. Ebel; C. C. Littlefield; D. C. Brater; S. H. Smiley

1959-01-01

204

Fast gradient screening of pharmaceuticals with 5 cm long, narrow bore reversed-phase columns packed with sub-3 ?m core-shell and sub-2 ?m totally porous particles.  

PubMed

The performance of 5 cm long narrow-bore columns packed with 2.6-2.7 ?m core-shell particles and a column packed with 1.7 ?m totally porous particles was compared in very fast gradient separations of polar neutral active pharmaceutical compounds. Peak capacities as a function of flow-rate and gradient time were measured. Peak capacities around 160-170 could be achieved within 25 min with these 5 cm long columns. The highest peak capacity was obtained with the Kinetex column however it was found that as the flow-rate increases, the peak capacity of the new Poroshell-120 column is getting closer to that obtained with the Kinetex column. Considering the column permeability, peak capacity per unit time and per unit pressure was also calculated. In this comparison the advantage of sub-3 ?m core-shell particles is more significant compared to sub-2 ?m totally porous particles. Moreover it was found that the very similar sized (d(p)=2.7 ?m) and structured (?=0.63) new Poroshell-120 and the earlier introduced Ascentis Express particles showed different efficiency. Results obtained showed that the 5 cm long narrow bore columns packed with sub-3 ?m core-shell particles offer the chance of very fast and efficient gradient separations, thus these columns can be applied for fast screening measurements of routine pharmaceutical analysis such as cleaning validation. PMID:21376967

Fekete, Szabolcs; Fekete, Jeno

2011-04-15

205

Fitting adsorption isotherms to the distribution data determined using packed micro-columns for high-performance liquid chromatography  

Microsoft Academic Search

Knowing the adsorption isotherms of the components of a mixture on the chromatographic system used to separate them is necessary for a better understanding of the separation process and for the optimization of the production rate and costs in preparative high-performance liquid chromatography (HPLC). Currently, adsorption isotherms are usually measured by frontal analysis, using conventional analytical columns. Unfortunately, this approach

Pavel Jandera; Simona Bun?eková; Kathleen Mihlbachler; Georges Guiochon; Veronika Ba?kovská; Josef Planeta

2001-01-01

206

Nuclear magnetic resonance studies of solvent flow through chromatographic columns: effect of packing density on flow patterns  

Microsoft Academic Search

NMR (nuclear magnetic resonance) techniques have been used to measure and characterise solvent flow through chromatographic columns. NMR imaging was used to track an injection of D2O. PGSE (pulsed gradient spin echo) NMR was used to measure the flow-rate dependence of axial and transverse apparent diffusion. A combination of these two techniques (dynamic NMR imaging) gave the spatial distribution of

Sally G. Harding; Herbert Baumann

2001-01-01

207

On-line arsenic co-precipitation on ethyl vinyl acetate turning-packed mini-column followed by hydride generation-ICP OES determination.  

PubMed

An alternative and new system for on-line preconcentration of arsenic by sorption on a mini-column associated to hydride generation--inductively coupled plasma--optical emission spectrometry determination was studied. It is based on the sorption of arsenic on a column packed with ethyl vinyl acetate (EVA) turnings and the use of La(III) as co-precipitant reagent. This polymeric material was employed here for the first time as filling material for column preconcentration. It could work both as adsorbent and as sieve material. Sample and co-precipitant agent (lanthanum nitrate) were off-line mixed and merged with ammonium buffer solution (pH 10.0), which promoted precipitation and quantitative collection on the small EVA turnings. The arsenic preconcentrated by co-precipitation with lanthanum hydroxide precipitate was subsequently eluted with hydrochloric acid, which was the medium used for hydride generation. Considering a flow rate of 5 ml/min, three enrichment factors were obtained, 28-, 38- and 45-fold at three different sampling times, 60, 120 and 180s; respectively. The detection limits (3s) obtained for each case were 0.013, 0.009 and 0.007 microg/l. Additionally, the calculated precisions expressed as relatively standard deviation (R.S.D.) were 0.9, 1.3 and 1.1%. Satisfactory results were obtained for the determination of arsenic in standard reference material NIST 1643e Trace Elements in Water and drinking water samples. PMID:17055643

Gil, R A; Ferrúa, N; Salonia, J A; Olsina, R A; Martinez, L D

2007-05-01

208

Catalytic distillation extends its reach  

SciTech Connect

Since the early 1980s, catalytic distillation processes have been selected by more than a hundred operators for various applications. Since such a unit performs both reaction and distillation simultaneously, a combined column can replace a separate, fixed-bed reactor and distillation column, thereby eliminating equipment and reducing capital costs. And, compared to the conventional approach, catalytic distillation may also improve other factors, such as reactant conversion, selectivity, mass transfer, operating pressure, oligomer formation and catalyst fouling. The constant washing of the catalyst by liquid flowing down the column and the distillation of high-boiling foulants results in extended catalyst life. Four selective hydrogenation applications of catalytic distillation are discussed: Butadiene selective hydrogenation combined within an MTBE unit; Pentadiene selective hydrogenation; C{sub 4} acetylene conversion; and Benzene saturation.

Rock, K.; McGuirk, T. [Catalytic Distillation Technologies, Houston, TX (United States); Gildert, G.R. [Catalytic Distillation Technologies, Pasadena, TX (United States)

1997-07-01

209

A study on in-situ electrolytic stripping of uranyl ion by using a closely packed glassy carbon fiber column electrode system  

SciTech Connect

Uranium(VI) in a tributyl phosphate organic phase was stripped into an aqueous phase by reduction of uranium(VI) to uranium(IV) in a closely packed GC fiber column electrode system. A model for in-situ uranium(VI) electrolytic stripping was suggested for the system. Uranium(VI) electroreduction occurred both in the organic phase and in the aqueous phase of the mixed phases. The uranium stripping yield increased and then became constant with the organic flow rate in the electrolytic system due to an increase of diffusion resistance of uranium ions in the organic phase into the aqueous phase. The aqueous flow rate, on the other hand, did not significantly affect the total uranium(VI) reduction current in the system. Electrolytic stripping was confirmed to be more effective than ordinary stripping without electrolysis.

Kim, K.W.; Lee, E.H.; Yoo, J.H. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)] [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of)

1999-09-01

210

Modelling reactive distillation  

Microsoft Academic Search

The design and operation issues for reactive distillation systems are considerably more complex than those involved for either conventional reactors or conventional distillation columns. The introduction of an in situ separation function within the reaction zone leads to complex interactions between vapor–liquid equilibrium, vapor–liquid mass transfer, intra-catalyst diffusion (for heterogeneously catalysed processes) and chemical kinetics. Such interactions have been shown

R. Taylor; R. Krishna

2000-01-01

211

Packed-column supercritical fluid chromatography for the analysis of isosorbide-5-mononitrate and related compounds in bulk substance and tablets.  

PubMed

We describe a packed-column supercritical fluid chromatographic method that can be used for the analysis of isosorbide-5-mononitrate (5-ISMN) bulk substance and the 5-ISMN content of Imdur tablets. The method is based on methanol-modified carbon dioxide as the mobile phase and porous graphitized carbon (PGC, Hypercarb) as column support at 40 degrees C and 100 bar back pressure. The method makes it possible to simultaneously determine 5-ISMN and related compounds. In order to elute NO(3)(-) with acceptable retention time a quarternary ammonium hydrogen sulfate salt is added to the methanol modifier. An almost linear increase of the retention time with increasing carbon content of the counter ion was found. Tetramethyl ammonium hydrogen sulfate 5 mM in methanol was used in the final method as polar modifier for the simultaneous determination of possible degradation products within 12 min. The present method can separate and detect related compounds such as isosorbide-2, 5-dinitrate, isomannidemononitrate and isosorbide-2-mononitrate at the 0.1% (w/w) level as required by regulatory guidelines. Nitrate can be detected down to about 0.02% (w/w). Repeated analyses of ground tablet powder gave an assay precision for isosorbide-5-mononitrate of 1.4% (R.S.D., eight samples and two injections of each). For related substances at an area percent of 0. 1 the precision was less than 10%. PMID:10869672

Gyllenhaal, O; Karlsson, A

2000-07-01

212

Sorption of Pb(II) onto a mixture of algae waste biomass and anion exchanger resin in a packed-bed column.  

PubMed

Sorption of Pb(II) was studied by using a biosorbent mixture of algae waste biomass and Purolite A-100 resin in a packed-bed column. Mixing these two components was done to prevent the clogging of the column and to ensure adequate flow rates. Increasing of solution flow rate and initial Pb(II) concentration make that the breakthrough and saturation points to be attained earlier. The experimental breakthrough curves were modeled using Bohart-Adams, Thomas and Yoon-Nelson models, and the parameters for all these models were calculated. A regeneration efficiency of 98% was achieved using 0.1 mol L(-1) HCl and not significant changes in lead uptake capacity after three biosorption/desorption cycles were noted. The biosorbent mixture was able to remove Pb(II) from synthetic wastewater at pH 5.0 and flow rate of 3.5 mL min(-1), and the obtained effluent has better quality characteristics. The biosorbent mixture it is suitable for a continuous system for large-scale applications. PMID:23262014

Bulgariu, Dumitru; Bulgariu, Laura

2013-02-01

213

Ammonia removal from wastewaters using natural Australian zeolite. 2. Pilot-scale study using continuous packed column process  

SciTech Connect

A pilot-scale process was designed and operated to investigate the continuous removal of ammonia from sewage using natural zeolite from Australia. The process consisted of a fixed-bed ion-exchange system operated in the downflow mode. Evaluation of the pilot process was initially undertaken for ammonia removal from tap water spiked with ammonium chloride to provide performance data in the absence of competing cations. The performance of the pilot process was then assessed using sewage as feed. Breakthrough curves were constructed for a range of treatment flow rates. Existing models for packed bed performance were shown to be able to predict the breakthrough behavior of the process. The results of a study are presented that show that Australian natural zeolite, clinoptilolite, may be successfully employed in a fixed-bed ion-exchange process to achieve high ammonia removal efficiencies from aqueous solution at rates commensurate with sand filtration. The rate of uptake of ammonium by the zeolite is sufficient to support a continuous high rate process.

Cooney, E.L.; Booker, N.A.; Shallcross, D.C.; Stevens, G.W.

1999-10-01

214

High-Pressure Gas Chromatography and Chromatography with Supercritical Fluids. II. Permeability and Efficiency of Packed Columns with High-Pressure Gases as Mobile Fluids under Conditions of Incipient Turbulence  

Microsoft Academic Search

The behavior of packed gas-liquid chromatographic columns using-carbon dioxide as a carrier gas has been studied at various pressures.Measurements of pressure drop as a function of flow rate indicated that at velocities normally used in gas chromatography the flow through the column becomes progressively more turbulent with increasing pressures above a few atmospheres. At conditions near the critical pressure the

S. T. Sie; G. W. A. Rijnders

1967-01-01

215

Investigation related to hydrogen isotopes separation by cryogenic distillation  

SciTech Connect

Research conducted in the last fifty years has shown that one of the most efficient techniques of removing tritium from the heavy water used as moderator and coolant in CANDU reactors (as that operated at Cernavoda (Romania)) is hydrogen cryogenic distillation. Designing and implementing the concept of cryogenic distillation columns require experiments to be conducted as well as computer simulations. Particularly, computer simulations are of great importance when designing and evaluating the performances of a column or a series of columns. Experimental data collected from laboratory work will be used as input for computer simulations run at larger scale (for The Pilot Plant for Tritium and Deuterium Separation) in order to increase the confidence in the simulated results. Studies carried out were focused on the following: - Quantitative analyses of important parameters such as the number of theoretical plates, inlet area, reflux flow, flow-rates extraction, working pressure, etc. - Columns connected in series in such a way to fulfil the separation requirements. Experiments were carried out on a laboratory-scale installation to investigate the performance of contact elements with continuous packing. The packing was manufactured in our institute. (authors)

Bornea, A.; Zamfirache, M.; Stefanescu, I.; Preda, A.; Balteanu, O.; Stefan, I. [INC-DTCI-ICSI Rm. Valcea, str.Uzinei, Nr.4, 240050 (Romania)

2008-07-15

216

Tert-Amyl Methyl Ether Catalytic Distillation Experiments and Simulations.  

National Technical Information Service (NTIS)

In this work the catalytic section of a reactive distillation column is studied. Experimental studies with a laboratory catalytic distillation column were carried out for the decomposition and production of tert-amyl methyl ether (TAME). The purpose of th...

K. Klemola A. Pyhaelahti

1996-01-01

217

Flooding characteristics of Goodloe packing  

Microsoft Academic Search

Experimental flooding data for the countercurrent flow of air and water in a 7.62-cm-diam glass column filled with Goodloe packing were compared with a correlation reported by the packing manufacturer. Flooding rates observed in this study were as low as one-half those predicted by the correlation. Rearranging the packing by inverting the column and removing some packing segments yielded results

J. M. Begovich; J. S. Watson

1976-01-01

218

Repeatability of the efficiency of columns packed with sub-3?m core-shell particles: Part III. 2.7?m Poroshell 120 EC-C18 particles in 4.6mm and 2.1mm × 100mm column formats.  

PubMed

As part of an investigation of the column-to-column repeatability of the efficiency of columns packed with sub-3?m shell particles, the parameters of the mass transfer kinetics of twelve columns packed with the same batch of 2.7?m Poroshell 120 EC-C(18) particles (Agilent Technologies, Little Fall, DE, USA) were sequentially measured, using columns provided by the manufacturers that were representative of the efficiency distribution given by the quality test control. The reduced longitudinal diffusion term (B) was measured using the peak parking (PP) method; the reduced solid-liquid mass transfer resistance term (C) was given by a combination of the PP results and the most accurate model of effective diffusion in ternary composite materials. The overall eddy diffusion term (A) was obtained by subtraction of these two HETP terms from the overall reduced HETP derived from the peak moments measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is a result of the random nature of the packing process and the eddy diffusion term resulting from the lack of homogeneity of the column bed. At the highest reduced velocity achieved for small analytes, the relative standard deviations (RSD) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 3 and 11% (with average values h(eddy)= 2.5 and 13.5) for naphthalene (k=3) and uracil (k=0), respectively. For the 4.6mm I.D. columns, these RSDs were 5 and 13%, respectively, with average values h(eddy)= 1.4 and 2.9. For insulin at reduced velocities as high as 160, the RSDs of the total reduced plate heights were 3 and 8% for the 2.1 and 4.6mm I.D. columns, respectively. PMID:22683189

Gritti, Fabrice; Guiochon, Georges

2012-08-24

219

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate. I-performance of 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles.  

PubMed

The mass transfer kinetics in short and wide 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles were measured for three different configurations of the inlet sample distribution and outlet sample collection: (1) both the inlet and outlet column endfittings are standard, (2) the inlet endfitting is standard while the outlet endfitting allows parallel segmentation of the exiting flow between a central and a peripheral region across the column diameter, and (3) both the inlet and outlet endfittings allow a parallel segmentation of the flow entering and exiting the column, respectively. The total reduced heights equivalent to a theoretical plate (HETP) were carefully measured, using the first and second central moments of the elution band profiles, obtained by its accurate numerical integration. The longitudinal diffusion term was measured at the lowest experimental reduced velocity applied. The solid-liquid mass transfer resistance was estimated from measurements of the intra-particle diffusivity using the Torquato's model of effective diffusion in packed beds. The trans-channel and short-range interchannel eddy diffusion HETP terms were taken from data obtained by solving numerically the Navier-Stokes equations and simulating advective-diffusive transport in computer-generated random sphere packings. The results clearly show that the trans-column eddy diffusion HETP term can account for up to 85% of the total intrinsic HETP (corrected for extra-column contributions) of the standard columns. Parallel segmented flow chromatography can reduce this contribution by half at high velocities, by eliminating most of the baseline peak tailing. This holds true irrespective of the retention factor of the analyte. It was found also that segmenting the inlet/outlet flow increases detection sensitivity by 25-50% for peaks with large to small retention factors, respectively. In practice, the advantage of parallel segmented flow chromatography in gradient elution (thin peak widths) is essentially limited by post-column bandspreading and diffusion in the dwell volume of the instrument used. Analyst should minimize post-column bandspreading (caused by connectors and detection cell volume) and synchronize the eluent composition in the peripheral and central inlet ports of the column, by using two separate pumps with appropriate dwell volumes. PMID:23706347

Gritti, Fabrice; Guiochon, Georges

2013-07-01

220

Repeatability of the efficiency of columns packed with sub-3?m core-shell particles: Part II. 2.7 ?m Halo-ES-Peptide-C18 particles in 4.6mm and 2.1mm×100mm column formats.  

PubMed

The column-to-column repeatability of the mass transfer kinetics in columns packed with sub-3?m shell particles was investigated. The parameters of this kinetics were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.7?m Halo-ES-Peptide-C(18) particles (Advanced Material Technologies, Wilmington, DE, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method; the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and the most accurate model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is mostly due to the random nature of the packing process and the associated eddy diffusion term. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 5 and 10% (with average values A(?)=2.3 and 8.5) for naphthalene and uracil, respectively. For the 4.6mm I.D. columns, these RSDs were 3 and 5%, respectively, with average values A(?)=1.5 and 2.7. PMID:22687713

Gritti, Fabrice; Guiochon, Georges

2012-08-24

221

Design of processes with reactive distillation line diagrams  

SciTech Connect

On the basis of the transformation of concentration coordinates, the concept of reactive distillation lines is developed. It is applied to study the feasibility of a reactive distillation with an equilibrium reaction on all trays of a distillation column. The singular points in the distillation line diagrams are characterized in terms of nodes and saddles. Depending on the characterization of the reactive distillation line diagrams, it can be decided whether a column with two feed stages is required. On the basis of the reaction space concept, a procedure for identification of reactive distillation processes is developed, in which the reactive distillation column has to be divided into reactive and nonreactive sections. This can be necessary to overcome the limitations in separation which result from the chemical equilibrium. The concentration profile of this combined reactive/nonreactive distillation column is estimated using combined reactive/nonreactive distillation lines.

Bessling, B. [BASF Ludwigshafen (Germany). Engineering Research and Development] [BASF Ludwigshafen (Germany). Engineering Research and Development; Schembecker, G.; Simmrock, K.H. [Univ. of Dortmund (Germany). Dept. of Chemical Engineering] [Univ. of Dortmund (Germany). Dept. of Chemical Engineering

1997-08-01

222

The adsorption of CO(2)/H(2)O/N(2) on 5A zeolite and silica gel in a packed column in one and two-dimensional flows  

NASA Astrophysics Data System (ADS)

The purpose of this work is to develop a computer model that simulates the dynamic behavior of a Four-Bed Molecular Sieves (4-BMS) system. The system will be installed on the International Space Station for removal of CO 2/H2O/N2 on four beds that consist of 5A zeolite, 13X zeolite, and Silica gel. Due to the complexity of the actual 4-BMS, separately packed columns of 5A and Silica gel were built and tested using the model results to obtain the mass and heat transfer coefficients necessary for the development of the 4-BMS. This work begins by introducing the adsorption/desorption process in a packed column. The formulation of the simplest model of adsorption in a packed bed is developed assuming that Darcy's law. In this model, the mass and heat transport gradients are assumed to vary only in the axial direction, i.e., one-dimensional flow. The results of temperature and mass transfer breakthrough of one-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H2O/N2 on 5A zeolite. In the packed column near the wall boundary, the velocity decreases due to the viscous forces and the porosity increases exponentially. This near-wall region of higher porosity results in the channeling of fluid close to the wall surface. This channeling causes an early solute breakthrough relative to the center of the column. In order to accommodate the effect of porosity variation on the breakthrough, a two-dimensional model of the packed column is developed. The results of two-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H 2O/N2 on 5A zeolite. This work also investigates the dynamics of H2O adsorption on Silica gel material. A one-dimensional flow of a packed column bed is developed with the assumption that Darcy's law governs the momentum transport. The results of both models are compared with the test results for adsorption of H 2O/N2 on Silica gel. Finally, a computer model based on the obtained parameters of independent bench testing is developed to simulate the actual 4-BMS. The cyclical results of each bed of 4-BMS are presented to show the required time to reach the steady state operation. The experimental results from the laboratory scale-fixed bed adsorber are quantitatively consistent with the one-dimensional model at the center of the bed. The average concentration from the bed obtained from test results deviates from the column center concentration appreciably. This indicates the strong effects of porosity variation along the radial direction of the bed on the temperature, concentration, and velocity profile. The two-dimensional model not only accurately predicts the concentration and temperature profile at the column center, but it also predicts the average concentration reasonably well.

Mohamadinejad, Habib

223

Distillation sequence for the purification and recovery of hydrocarbons  

Microsoft Academic Search

This invention is an improved distillation sequence for the separation and purification of ethylene from a cracked gas. A hydrocarbon feed enters a C2 distributor column. The top of the C2 distributor column is thermally coupled to an ethylene distributor column, and the bottoms liquid of a C2 distributor column feeds a deethanizer column. The C2 distributor column utilizes a

Rian Reyneke; Michael Foral; Christos G. Papadopoulos; Jeffrey S. Logsdon; Wayne W. Y. Eng; Guang-Chung Lee; Ian Sinclair

2007-01-01

224

Packed tower distributors tested  

SciTech Connect

Various distributor designs are tested by using a computer model to simulate the liquid flow through a packed bed. The effects of nonhomogeneous liquid flow within the distributor also are studied. The results show the design of the distributor can have a marked effect on the overall efficiency and operation of a packed column. The conclusions are as follows: Every packing has a natural liquid flow distribution. No matter how perfect or imperfect the initial distribution is, the flows will tend toward the natural distribution. Given a deep enough packing bed, the natural distribution will be reached. Perfect distribution will degrade to natural. Maldistribution will improve--sometimes very slowly--to natural. For any real distributor, there is an initial distribution-other than perfect--that will minimize the bed depth required to reach natural distribution. The best drip pan distributor is one that has one drip point for each 10 to 12 pieces of packing in the top layer of packing. The best single spray distributor is one that just reaches the column wall and is as near homogeneous as possible. The best seven-spot multiple spray is a set that overlap and is adjusted so that the column diameter/individual spray diameter (at the packing surface) is about 2.4. Each individual spray must be as homogeneous as possible.

Albright, M.A.

1984-09-01

225

Petroleum Distillates.  

National Technical Information Service (NTIS)

This report provides data for the evaluation of the safety of certain petroleum distillate fractions used in commercial products to which consumers may be exposed. Chemical information and data on the toxicology, pharmacology and relevent biology are comp...

J. Villaume P. Walter R. Levine A. Craigmill H. Schwartz

1976-01-01

226

Solar Distillation  

Microsoft Academic Search

\\u000a “Solar distillation” is a technology for producing potable water from brackish and underground water of low-quality at low\\u000a cost. It can reduce water-scarcity problems together with other water purification technologies. Solar distillation is analogous\\u000a to natural hydrological cycle. It uses an apparatus called a solar still in which water is evaporated using solar energy,\\u000a a form of renewable energy, and

Rahul Dev; Gopal Nath Tiwari

227

Column oriented Database Systems  

Microsoft Academic Search

Column-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as opposed to traditional database systems that store entire records (rows) one after the other. Reading a subset of a table's

Daniel J. Abadi; Peter A. Boncz; Stavros Harizopoulos

2009-01-01

228

Liquid distribution studies in packed beds  

Microsoft Academic Search

Recent research has shown that liquid distribution is even more important to the apparent efficiency of packed columns than was previously believed. An ''Adjustable Liquid Distributor'' which allows distribution to be changed with the column in operation has been designed and is being used to gain more insight into packed column operation. Preliminary conclusions are that discontinuities and zonal flows

J. G. Kunesh; L. L. Lahm; T. Yanagi

1985-01-01

229

Determination of chromium(VI) and lead in water samples by on-line sorption preconcentration coupled with flame atomic absorption spectrometry using a PCTFE-beads packed column  

Microsoft Academic Search

A new time-based flow injection on-line solid phase extraction method for chromium(VI) and lead determination using flame atomic absorption spectrometry was developed. The use of hydrophobic poly-chlorotrifluoroethylene (PCTFE)-beads as absorbent in on-line preconcentration system was evaluated. Effective formation of ammonium pyrrolidine dithiocarbamate complexes and subsequently retention in PCTFE packed column, was achieved in pH range 1.0–1.6 and 1.5–3.2 for Cr(VI)

Aristidis N. Anthemidis; Salome-Juliette V. Koussoroplis

2007-01-01

230

Method for packing chromatographic beds  

DOEpatents

Column chromatography beds are packed through the application of static force. A slurry of the chromatography bed material and a non-viscous liquid is filled into the column plugged at one end, and allowed to settle. The column is transferred to a centrifuge, and centrifuged for a brief period of time to achieve a predetermined packing level, at a range generally of 100-5,000 gravities. Thereafter, the plug is removed, other fixtures may be secured, and the liquid is allowed to flow out through the bed. This results in an evenly packed bed, with no channeling or preferential flow characteristics.

Freeman, David H. (Potomac, MD); Angeles, Rosalie M. (Germantown, MD); Keller, Suzanne (Rockville, MD)

1991-01-01

231

Synthesis of azeotropic batch distillation separation systems  

SciTech Connect

The sequencing of batch distillation systems, in particular batch distillation columns, can be complicated by the existence of azeotropes in the mixture. These azeotropes can form batch distillation regions where, depending on the initial feed to the batch column, the types of feasible products and separations are limited. It is very important that these distillation regions are known while attempting to synthesize sequences of batch columns so infeasible designs can be eliminated early on in the design phase. The distillation regions also give information regarding the feasible products that can be obtained when the mixture is separated by using a variety of batch column configurations. The authors will show how a tool for finding the batch distillation regions of a particular mixture can be used in the synthesis of batch distillation column sequences. These sequences are determined by the initial feed composition to the separation network. The network of all possible sequences will be generated by using state-task networks when batch rectifying, stripping, middle vessel, and extractive middle vessel columns are allowed. The authors do not determine which sequence is the best, as the best sequence will depend on the particular application to which one is applying the algorithms. They show an example problem for illustration of this technique.

Safrit, B.T. [Eastman Chemical Co., Kingsport, TN (United States)] [Eastman Chemical Co., Kingsport, TN (United States); Westerberg, A.W. [Carnegie Mellon Univ., Pittsburgh, PA (United States)] [Carnegie Mellon Univ., Pittsburgh, PA (United States)

1997-05-01

232

Characteristics of molybdate-impregnated chitosan beads (MICB) in terms of arsenic removal from water and the application of a MICB-packed column to remove arsenic from wastewater.  

PubMed

The removal of arsenic (As) species, such as As(III) and As(V), from water by molybdate-impregnated chitosan beads (MICB) in both batch and continuous operations was studied. The effects of pH, temperature, coexisting ions, and arsenic concentrations were studied in batch tests. Studies on the kinetic adsorption of MICB, the recovery of arsenic by the desorption solution, and the reuse of MICB were also carried out. The practicality and efficiency of an MCIB-packed column on arsenic removal were evaluated in a continuous system on industrial arsenic-containing wastewater discharged during the manufacture of GaAs supports. The results indicate that MICB favor the adsorption of both As(V) and As(III). The optimal pH value for As(III) and As(V) removal was 5. The adsorption of arsenic on the MICB is most likely an exothermic reaction. The effect of coexisting ions was varied and depended on their concentrations and species. The optimal desorption solution for arsenic recovery was 1M H2SO4, which resulted in a 95% efficiency for As(III) and 99% for As(V). In the continuous tests, the MICB-packed column exhibited excellent arsenic removal from wastewater without any pretreatment. These results provide strong evidence of the potential of MICB for removing As from industrial wastewaters. PMID:18359225

Chen, Chih-Yu; Chang, Tsu-Hua; Kuo, Jong-Tar; Chen, Yu-Feng; Chung, Ying-Chien

2008-11-01

233

Membrane distillation  

Microsoft Academic Search

This paper provides a state-of-the-art review of the separation process known as membrane distillation, MD. An introduction to the terminology and fundamental concepts associated with MD as well as a historical review of the developments in MD are presented. Membrane properties, transport phenomena, and module design are discussed in detail. A critical evaluation of the MD literature is incorporated throughout

Kevin W. Lawson; Douglas R. Lloyd

1997-01-01

234

Flooding Characteristics of Goodloe Packing.  

National Technical Information Service (NTIS)

Experimental flooding data for the countercurrent flow of air and water in a 7.62-cm-diam glass column filled with Goodloe packing were compared with a correlation reported by the packing manufacturer. Flooding rates observed in this study were as low as ...

J. M. Begovich J. S. Watson

1976-01-01

235

Idle time in the washing and iron concentration in leachate removed: two basic parameters in the desulphurization of coal in a packed column  

Microsoft Academic Search

Column biodesulphurization of coal is at the experimental stage and is influenced by many variables including temperature, pH, particle size, concentration of iron in solution, among others. Idle time in the washing process and the concentration of dissolved iron in the purged leachate are two variables with a definite effect on the yield of the desulphurization system. In the laboratory,

J. Cara; A. Aller; M. Otero; A. Morán

2001-01-01

236

The rationale for the optimum efficiency of columns packed with new 1.9?m fully porous Titan-C18 particles-A detailed investigation of the intra-particle diffusivity.  

PubMed

In a previous report, it was reported that columns packed with fully porous 1.9?m Titan-C18 particles provided a minimum reduced plate height as small as 1.7 for the most retained compound (n-octanophenone) under RPLC conditions. These particles are characterized by a relatively narrow size distribution with a relative standard deviation (RSD) of only 10%. A column packed with classical 5?m Symmetry-C18 particles, used as a reference RPLC column, generated a minimum reduced plate height of 2.1 for the same retained compound. This work demonstrates that this was due to an unusually low intra-particle diffusivity across these particles, which leads to a small longitudinal diffusion coefficient along the column. The demonstration is based on the combination of accurate measurements of the height equivalent to a theoretical plate (HETP), inverse size exclusion chromatography (ISEC), peak parking (PP), and minor disturbance method (MDM) experiments. The experimental results show that the reduced eddy dispersion HETP term (A=0.8 for a reduced velocity of 5), the internal particle porosity (?p=0.35), and the enrichment of acetonitrile in the pore volume (75% acetonitrile in the bulk, 85% inside the mesoporous volume) are identical on both the Titan-C18 and Symmetry-C18 columns. The difference between the internal structures of these two brands of RPLC-C18 fully porous particles lies in the values of the internal obstruction factor ?p, which is 0.42 for the Symmetry-C18 but only 0.26 for the Titan-C18 particles. This is in part related to the diffusion hindrance due to the small average pore size of the Titan-C18 particles, around 59? versus 77? for Symmetry-C18 particles. A simple model of constriction along diffusion paths having the shape of a truncated cone suggests that the width of the pore size distribution (RSD of 30% and 20% for Titan-C18 and Symmetry-C18 particles) is mostly responsible for the difference in their obstruction factors. PMID:24969087

Gritti, Fabrice; Guiochon, Georges

2014-08-15

237

Distributive Distillation Enabled by Microchannel Process Technology  

SciTech Connect

The application of microchannel technology for distributive distillation was studied to achieve the Grand Challenge goals of 25% energy savings and 10% return on investment. In Task 1, a detailed study was conducted and two distillation systems were identified that would meet the Grand Challenge goals if the microchannel distillation technology was used. Material and heat balance calculations were performed to develop process flow sheet designs for the two distillation systems in Task 2. The process designs were focused on two methods of integrating the microchannel technology â?? 1) Integrating microchannel distillation to an existing conventional column, 2) Microchannel distillation for new plants. A design concept for a modular microchannel distillation unit was developed in Task 3. In Task 4, Ultrasonic Additive Machining (UAM) was evaluated as a manufacturing method for microchannel distillation units. However, it was found that a significant development work would be required to develop process parameters to use UAM for commercial distillation manufacturing. Two alternate manufacturing methods were explored. Both manufacturing approaches were experimentally tested to confirm their validity. The conceptual design of the microchannel distillation unit (Task 3) was combined with the manufacturing methods developed in Task 4 and flowsheet designs in Task 2 to estimate the cost of the microchannel distillation unit and this was compared to a conventional distillation column. The best results were for a methanol-water separation unit for the use in a biodiesel facility. For this application microchannel distillation was found to be more cost effective than conventional system and capable of meeting the DOE Grand Challenge performance requirements.

Arora, Ravi

2013-01-22

238

A comparison of the properties of polyurethane immobilised Sphagnum moss, seaweed, sunflower waste and maize for the biosorption of Cu, Pb, Zn and Ni in continuous flow packed columns.  

PubMed

The biosorption of Cu, Pb, Zn and Ni from a mixed solution of the metals was investigated in continuous flow packed columns containing polyurethane immobilised biomass. The characteristics and biosorption properties of Sphagnum moss, the brown seaweed Ascophyllum nodosum, waste biomass from the preparation of sunflower oil, and whole plant maize were compared. All the biomass types showed a preference for the sequestration of Pb followed by Cu, with Ni and Zn having roughly equal affinity. With continuous metal loading to the column there was an initial binding of all metals and then a displacement of the lower affinity metals by those with a high affinity. This led to a chromatographic effect in the column with breakthrough concentrations for low-affinity metals higher than the concentration in the feed. A similar phenomenon was found on desorption using acidic solutions where low-affinity metals were desorbed preferentially. The results also indicated that despite competitive displacement of one metal species by another the biomass appeared to succeed in retaining some low-affinity metal species indicating that there may be selective sites present with different affinity characteristics. When using a multi-metal solution with Cu, Pb, Zn and Ni at equal 10 mgl(-1) concentrations as column influent, the total quantities of metal sequestered were: seaweed, 117.3 mg g(-1); sunflower waste, 33.2 mg g(-1); Sphagnum moss, 32.5 mg g(-1); and maize, 2.3 mg g(-1). The use of an acid base potentiometric titration showed a relationship between the number of acid functional groups and biosorption capacity, although this was not proportional for the biomass types studied. It can, however, be used in conjunction with a simple classification of metals into high and low-affinity bands to make a preliminary assessment of a biosorption system. PMID:16448685

Zhang, Yue; Banks, Charles

2006-02-01

239

High throughput screening of mixed-mode sorbents and optimisation using pre-packed lab-scale columns for the purification of the recombinant allergen rBet v 1a.  

PubMed

Mixed-mode chromatography was investigated for the purification of the recombinant allergen rBet v 1a expressed in Escherichia coli (E. coli) and used as an active principle for specific immunotherapy (SIT) treatment against birch pollen allergy. The screening of micro-volumes of three mixed-mode sorbents established that rBet v 1a could be captured without any pre-treatment of the crude feedstock on HEA or PPA HyperCel sorbents equilibrated in "physiological-like" conditions. On a mini-column pre-packed with PPA HyperCel sorbent, rBet v 1a was recovered at pH 4, partially separated from a major methionine Bet v 1 contaminant and purified approximately 9-fold in a single step (85% purity). PMID:19345650

Brenac Brochier, Virginie; Chabre, Henri; Lautrette, Aurélie; Ravault, Vincent; Couret, Marie-Noëlle; Didierlaurent, Alain; Moingeon, Philippe

2009-08-15

240

Column-switching system with restricted access pre-column packing for an integrated sample cleanup and liquid chromatographic–mass spectrometric analysis of alkylphenolic compounds and steroid sex hormones in sediment  

Microsoft Academic Search

A novel methodology based on column switching LC–MS, using restricted access material (RAM), for an integrated sample clean-up and analysis of endocrine disrupting compounds in sediment samples is described. The use of RAM precolumns, that combines size exclusion and reversed-phase retention mechanisms, enables fast on-line clean-up of sediment extracts and sensitive determination of alkylphenolic compounds, bisphenol A and steroid sex

Mira Petrovic; Simona Tavazzi; Damia Barcelo

2002-01-01

241

Fast generic-gradient reversed-phase high-performance liquid chromatography using short narrow-bore columns packed with small nonporous silica particles for the analysis of combinatorial libraries.  

PubMed

The extremely large number of samples generated for the quality control analysis of combinatorial libraries that are developed in the pharmaceutical research for drug discovery requires fast generic methods such as rapid-gradient reversed-phase high-performance liquid chromatography (HPLC). These methods are necessary as standard procedures to produce up to several hundreds of analytical results per day and should be optimized in order to be applied to library products of widely differing polarities. This work presents an optimized generic method using a narrow-bore column packed with 1.5-microm nonporous particles and a completely automated HPLC workstation configured for the best efficiency, throughput, and robustness with this column. A test mix of 12 compounds with a wide polarity range is separated within 1.5 min with a cycle time of 3.5 min. The throughput is further enhanced using a Gilson 233XL dual-injection sampler to feed two parallel HPLC systems in order to perform 34 analyses per hour. PMID:11718310

Leroy, F; Presle, B; Vérillon, F; Vérette, E

2001-11-01

242

Breakthrough studies with mono-, binary- and ternary-ion systems comprised of Fe(II), F(-) and As(III) using river sand packed columns for groundwater treatment.  

PubMed

Groundwater in Assam, India, contains excessive amounts of arsenic (As(III)), fluoride (F(-)) and iron (Fe(II)). The rural and semi-urban population of Assam uses indigenous iron filters fabricated using processed sand (PS) as one of the chief constituents to reduce Fe(II) concentration; however, no efforts have been made to reduce As(III) or F(-) concentrations before use. The present work is directed towards assessing the potential of PS for removal of these ions from mono-, binary- and ternary-ion systems through continuous mode column studies. Synthetic water samples containing fixed concentration of ions were prepared using deionized water. The observed order of breakthrough of ions was: As(III) followed by Fe(II) and F(-) followed by Fe(II) in the case of the binary ion systems of Fe(II) + As(III) and Fe(II) + F(-). The throughput volume for As(III) in the (Fe(II) + As(III)) system and for F(-) in the (Fe(II) + F(-)) system is termed the critical breakthrough throughput volume. In the ternary ion system (Fe(II) + As(III) + F(-)), the order of breakthrough of ions observed was F(-), then As(III) and then Fe(II) and hence the throughput volume F(-) is termed the critical breakthrough throughput volume. Results of column studies also indicate the impact on the uptake of the selected ion by the presence of the other ion present in the binary- and ternary-ion systems. PMID:23708571

Ahamad, Kamal Uddin; Jawed, Mohammad

2013-06-01

243

Multiple steady states during reactive distillation of methyl tert-butyl ether  

Microsoft Academic Search

This paper presents results of computer simulations of the synthesis of methyl tert-butyl ether (MTBE) in a fixed-bed reactor and in a reactive distillation column. These calculations clearly showed the advantages of MTBE synthesis in a catalytic distillation tower. Furthermore, the computer simulations showed that multiple steady states may occur in the reactive distillation column during MTBE synthesis in a

S. A. Nijhuis; F. P. J. M. Kerkhof; A. N. S. Mak

1993-01-01

244

Liquid distribution studies in packed beds  

SciTech Connect

Recent research has shown that liquid distribution is even more important to the apparent efficiency of packed columns than was previously believed. An ''Adjustable Liquid Distributor'' which allows distribution to be changed with the column in operation has been designed and is being used to gain more insight into packed column operation. Preliminary conclusions are that discontinuities and zonal flows have the most severe impact on efficiency.

Kunesh, J.G.; Lahm, L.L.; Yanagi, T.

1985-01-01

245

Pack Saddle  

USGS Multimedia Gallery

This is a pack saddle used by Arnold Hague in the late 1800s. The wooden saddle has leather straps and a cinch used for the animal's comfort when carrying especially large loads. Pack saddles could be used to carry panniers or other large objects. Object ID: USGS-000014...

2009-07-22

246

Attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum cultured under varying conditions to pyrite, chalcopyrite, low-grade ore and quartz in a packed column reactor.  

PubMed

The attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum spp. grown on ferrous medium or adapted to a pyrite mineral concentrate to four mineral substrata, namely, chalcopyrite and pyrite concentrates, a low-grade chalcopyrite ore (0.5 wt%) and quartzite, was investigated. The quartzite represented a typical gangue mineral and served as a control. The attachment studies were carried out in a novel particle-coated column reactor. The saturated reactor containing glass beads, which were coated with fine mineral concentrates, provided a quantifiable surface area of mineral concentrate and maintained good fluid flow. A. ferrooxidans and Leptospirillum spp. had similar attachment characteristics. Enhanced attachment efficiency occurred with bacteria grown on sulphide minerals relative to those grown on ferrous sulphate in an ore-free environment. Selective attachment to sulphide minerals relative to gangue materials occurred, with mineral adapted cultures attaching to the minerals more efficiently than ferrous grown cultures. Mineral-adapted cultures showed highest levels of attachment to pyrite (74% and 79% attachment for A. ferrooxidans and L. ferriphilum, respectively). This was followed by attachment of mineral-adapted cultures to chalcopyrite (63% and 58% for A. ferrooxidans and L. ferriphilum, respectively). A. ferrooxidans and L. ferriphilum exhibited lower levels of attachment to low-grade ore and quartz relative to the sulphide minerals. PMID:22410741

Africa, Cindy-Jade; van Hille, Robert P; Harrison, Susan T L

2013-02-01

247

Distillation tray structural parameter study: Phase 1  

NASA Technical Reports Server (NTRS)

The purpose here is to identify the structural parameters (plate thickness, liquid level, beam size, number of beams, tray diameter, etc.) that affect the structural integrity of distillation trays in distillation columns. Once the sensitivity of the trays' dynamic response to these parameters has been established, the designer will be able to use this information to prepare more accurate specifications for the construction of new trays. Information is given on both static and dynamic analysis, modal response, and tray failure details.

Winter, J. Ronald

1991-01-01

248

Distillation sequence for the purification and recovery of hydrocarbons  

DOEpatents

This invention is an improved distillation sequence for the separation and purification of ethylene from a cracked gas. A hydrocarbon feed enters a C2 distributor column. The top of the C2 distributor column is thermally coupled to an ethylene distributor column, and the bottoms liquid of a C2 distributor column feeds a deethanizer column. The C2 distributor column utilizes a conventional reboiler. The top of the ethylene distributor is thermally coupled with a demethanizer column, and the bottoms liquid of the ethylene distributor feeds a C2 splitter column. The ethylene distributor column utilizes a conventional reboiler. The deethanizer and C2 splitter columns are also thermally coupled and operated at a substantially lower pressure than the C2 distributor column, the ethylene distributor column, and the demethanizer column. Alternatively, a hydrocarbon feed enters a deethanizer column. The top of the deethanizer is thermally coupled to an ethylene distributor column, and the ethylene distributor column utilizes a conventional reboiler. The top of the ethylene distributor column is thermally coupled with a demethanizer column, and the bottoms liquid of the ethylene distributor column feeds a C2 splitter column. The C2 splitter column operates at a pressure substantially lower than the ethylene distributor column, the demethanizer column, and the deethanizer column.

Reyneke, Rian (Katy, TX) [Katy, TX; Foral, Michael (Aurora, IL) [Aurora, IL; Papadopoulos, Christos G. (Naperville, IL) [Naperville, IL; Logsdon, Jeffrey S. (Naperville, IL) [Naperville, IL; Eng, Wayne W. Y. (League City, TX) [League City, TX; Lee, Guang-Chung (Houston, TX) [Houston, TX; Sinclair, Ian (Warrington, GB) [Warrington, GB

2007-12-25

249

Dual Column Operation for Gas Chromatograph-Mass Spectrometer.  

National Technical Information Service (NTIS)

An arrangement to operate dual columns, i.e. a capillary and a packed column in a gas chromatograph-mass spectrometer is described. The packed column provides the make-up for the capillary column so that the molecular separator can be retained in the syst...

L. Kazyak

1976-01-01

250

Experimental verification of the equilibrium stage model for the dynamics of the multicomponent distillation considering the effects of energy loss  

SciTech Connect

This paper on the dynamics of multicomponent distillation is based on experimental investigations in a laboratory-scale distillation column. The concentration and temperature profiles are obtained at the steady-state operating point, and the transition behavior is observed by systematically changing the relevant operating variables. The general scope of these experiments is to evaluate and study the concentration and temperature profiles measured along the column height. The developed methodology for sampling at vacuum is explained. The experimental results are compared with theoretical calculations obtained by means of steady-state and dynamic simulation. The influence and the important of heat losses on the steady-state and dynamic behavior at high temperature levels are investigated and discussed. The aim of these studies is to prove the steady-state and dynamic simulation tool on the basis of the equilibrium stage model. It is found that the simulation results agree closely with those obtained experimentally. This refers to the concentration and temperature profiles as well as to the calculated and the experimentally used reboiler heat input. In order to achieve this good agreement, heat losses along the column height have to be taken into account in the simulation. Consequently, the consideration of heat losses is of great importance for the determination of HETP values in packed columns.

Kruse, C. [COGNIS GmbH, Duesseldorf (Germany); Fieg, G.; Jeromin, L.; Johannisbauer, W. [Henkel KGaA, Duesseldorf (Germany); Wozny, G. [TU Berlin (Germany). Inst. fuer Prozess- und Anlagentechnik

1995-05-01

251

Setting the Pressure at Which to Conduct a Distillation.  

ERIC Educational Resources Information Center

Discusses how pressure setting is determined for distillation columns, examining factors which must be considered when optimizing design for economical balance. Also discusses the basics of heat exchangers and cites a common problem with pressure differences. (JM)

Barduhn, Allen J.

1984-01-01

252

Distillation with Vapour Compression. An Undergraduate Experimental Facility.  

ERIC Educational Resources Information Center

Discusses the need to design distillation columns that are more energy efficient. Describes a "design and build" project completed by two college students aimed at demonstrating the principles of vapour compression distillation in a more energy efficient way. General design specifications are given, along with suggestions for teaching and…

Pritchard, Colin

1986-01-01

253

Multiplicity Analysis in Reactive Distillation Column Using ASPEN PLUS 1 1 Supported by the Key Project of National Natural Science Foundation of China (No.20436040) and the National Natural Science Foundation of China (No.20176044, No.20476084)  

Microsoft Academic Search

Reactive distillation processes for synthesis of ethylene glycol (EG) and ethyl tert-butyl ether (ETBE) were modeled with the simulation package ASPEN PLUS. The input multiplicity and output multiplicity were discussed with the method of sensitivity analysis for both cases. In EG production process, steady state multiplicities were studied in terms of effective liquid holdup volume and boil-up ratio. In ETBE

Bolun YANG; Jiang WU; Guosheng ZHAO; Huajun WANG; Shiqing LU

2006-01-01

254

Valve Packing  

NASA Technical Reports Server (NTRS)

"S Glass" yarn was originally developed by NASA for high temperature space and aeronautical applications. When John Crane, Inc. required material that would withstand temperatures higher than 1,200 degrees Fahrenheit, they contacted Owens-Corning, which had developed a number of applications for the material. John Crane combines the yarn with other components to make Style 287-I packing. The product can be used in chemical processing operations, nuclear power stations, petroleum products, etc. Advantages include increased service life and reduced maintenance costs.

1992-01-01

255

Two-Dimensional Packing of Short DNA with Non-Pairing Overhangs in Cationic Liposome-DNA Complexes: From Onsager Nematics to Columnar Nematics With Finite-Length Columns  

PubMed Central

We report the formation of liquid crystalline (LC) phases of short double-stranded DNA with non-pairing (non-sticky) overhangs, confined between two-dimensional (2D) lipid bilayers of cationic liposome–DNA complexes. In a landmark study (Science 2007, 318, 1276), Nakata et al. reported on the discovery of strong end-to-end stacking interactions between short DNAs (sDNAs) with blunt ends leading to the formation of 3D nematic (N) and columnar LC phases. Employing synchrotron small-angle X-ray scattering, we have studied the interplay between shape anisotropy-induced and DNA end-to-end interaction-induced N ordering for 11 bp, 24 bp, and 48 bp sDNA rods with single-stranded oligo-thymine (T) overhangs modulating the end-to-end interactions. For suppressed stacking interactions with 10-T overhangs, the volume fraction of sDNA at which the 2D isotropic (I) to N transition occurs for 24 bp and 48 bp sDNA rods depended on their length to width (L/D) shape anisotropy, qualitatively consistent with Onsager's theory for the entropic alignment of rigid rods. As the overhang length is reduced from 10 T to 5 T and 2 T for 24 bp and 48 bp sDNA, the N to I transition occurs at lower volume fractions, indicating the onset of some degree of end-to-end stacking interactions. The 11 bp sDNA rods with 5-T and 10-T overhangs remain in the I phase, consistent with their small shape anisotropy (L/D ? 1.9) below the limit for Onsager LC ordering. Unexpectedly, in contrast to the behavior of 24 bp and 48 bp sDNA, the end-to-end interactions between 11 bp sDNA rods with 2-T overhangs set in dramatically and a novel 2D columnar N phase (NC) with finite-length columns formed. The building blocks of this phase are comprised of 1D stacks of (on average) four 11bp DNA-2T rods with an effective LSTACKED/D ? 8.2. Our findings have implications for the DNA-directed assembly of nanoparticles on 2D platforms via end-to-end interactions and in designing optimally packed LC phases of short anisotropic biomolecules (such as peptides and short-interfering RNAs) on nanoparticle membranes, which are used in gene silencing and chemical delivery.

Bouxsein, Nathan F.; Leal, Cecilia; McAllister, Christopher S.; Ewert, Kai K.; Li, Youli; Samuel, Charles E.; Safinya, Cyrus R.

2011-01-01

256

Production of uniform packing blocks using bag filters  

Microsoft Academic Search

The authors describe a method for intensifying the heat transfer and hydraulic conductivity and, consequently, the overall energy efficiency of a petroleum extraction column by the implementation of bag filters as the packing medium. Diagrams and schematics of the proposed column are presented and test results are cited indicating the high efficiency of the crosscurrent packing design for a wide

K. F. Bogatykh; I. A. Mnushkin

1988-01-01

257

Random close packing of polydisperse jammed emulsions  

NASA Astrophysics Data System (ADS)

Packing problems are everywhere, ranging from oil extraction through porous rocks to grain storage in silos and the compaction of pharmaceutical powders into tablets. At a given density, particulate systems pack into a mechanically stable and amorphous jammed state. Theoretical frameworks have proposed a connection between this jammed state and the glass transition, a thermodynamics of jamming, as well as geometric modeling of random packings. Nevertheless, a simple underlying mechanism for the random assembly of athermal particles, analogous to crystalline ordering, remains unknown. Here we use 3D measurements of polydisperse packings of emulsion droplets to build a simple statistical model in which the complexity of the global packing is distilled into a local stochastic process. From the perspective of a single particle the packing problem is reduced to the random formation of nearest neighbors, followed by a choice of contacts among them. The two key parameters in the model, the available space around a particle and the ratio of contacts to neighbors, are directly obtained from experiments. Remarkably, we demonstrate that this ``granocentric'' view captures the properties of the polydisperse emulsion packing, ranging from the microscopic distributions of nearest neighbors and contacts to local density fluctuations and all the way to the global packing density. Further applications to monodisperse and bidisperse systems quantitatively agree with previously measured trends in global density. This model therefore reveals a general principle of organization for random packing and lays the foundations for a theory of jammed matter.

Brujic, Jasna

2010-03-01

258

Kinetic Method for Hydrogen-Deuterium-Tritium Mixture Distillation Simulation  

SciTech Connect

Simulation of hydrogen distillation plants requires mathematical procedures suitable for multicomponent systems. In most of the present-day simulation methods a distillation column is assumed to be composed of theoretical stages, or plates. However, in the case of a multicomponent mixture theoretical plate does not exist.An alternative kinetic method of simulation is depicted in the work. According to this method a system of mass-transfer differential equations is solved numerically. Mass-transfer coefficients are estimated with using experimental results and empirical equations.Developed method allows calculating the steady state of a distillation column as well as its any non-steady state when initial conditions are given. The results for steady states are compared with ones obtained via Thiele-Geddes theoretical stage technique and the necessity of using kinetic method is demonstrated. Examples of a column startup period and periodic distillation simulations are shown as well.

Sazonov, A.B.; Kagramanov, Z.G.; Magomedbekov, E.P. [Mendeleyev University of Chemical Technology of Russia (Russian Federation)

2005-07-15

259

Distillation of liquid fuels by thermogravimetry  

SciTech Connect

The most widely used separation technique in the petroleum industry and other liquid fuel production processes as well as in much of the chemical industry is distillation. To design and operate an appropriate commercial and laboratory distillation unit requires a knowledge of the boiling point distribution of the materials to be separated. In recognition of these needs, the ASTM developed the distillation procedures of D86, D216, D447, D850, and D1078. They are widely used in laboratories for the purposes of sample characterization, product and quality control, and distillation column design. However, the significant drawbacks of these ASTM methods include (1) close monitoring of the distillation is required. This is particularly difficult for those samples which are very toxic and/or cause any other safety problems; (2) the sample under test must be transparent and free of separated water; and (3) results obtained by these methods are not particularly precise. This motivated the development of a novel automatic distillation system based on the use of a custom-built thermogravimetric apparatus.

Huang, He; Wang, Keyu; Wang, Shaojie [Univ. of Delaware, Newark, DE (United States)] [and others

1996-12-31

260

A Non-Wetting Packed Bed Gas Scrubber  

Microsoft Academic Search

The operation of a small-scale packed column working under non-wetting condition was investigated to provide insight and design data for the subsequent development of a liquid metal irrigated packed bed gas scrubber. An 8cm internal diameter Perspex column was used, packed with 9.5mm polyethylene spheres and 10.0mm glass spheres coated with paraffin wax. A counter-current air–water system was used. The

B. F. Chang; J. Swithenbank; V. N. Sharifi

2007-01-01

261

Multipartite nonlocality distillation  

SciTech Connect

The stronger nonlocality than that allowed in quantum theory can provide an advantage in information processing and computation. Since quantum entanglement is distillable, can nonlocality be distilled in the nonsignalling condition? The answer is positive in the bipartite case. In this article the distillability of the multipartite nonlocality is investigated. We propose a distillation protocol solely exploiting xor operations on output bits. The probability-distribution vectors and matrix are introduced to tackle the correlators. It is shown that only the correlators with extreme values can survive the distillation process. As the main result, the amplified nonlocality cannot maximally violate any Bell-type inequality. Accordingly, a distillability criterion in the postquantum region is proposed.

Hsu, Li-Yi; Wu, Keng-Shuo [Department of Physics, Chung Yuan Christian University, Chungli 32023, Taiwan (China)

2010-11-15

262

Calculation of parametric sensitivity in binary batch distillation  

Microsoft Academic Search

This paper provides a comprehensive analysis of parametric sensitivity of batch distillation operations to perturbations in the feed composition. Three column arrangements are considered: batch rectifiers, batch strippers and total-reflux columns. The perturbation dynamics is parameterized in such a way as to allow the analytical calculation of the sensitivity function in the whole composition range, for both sharp and non-sharp

Massimiliano Barolo; Franco Botteon

1998-01-01

263

29 CFR 1926.755 - Column anchorage.  

Code of Federal Regulations, 2013 CFR

...the top of the column shaft. (3) Columns shall be set on level finished floors, pre-grouted leveling plates, leveling nuts, or shim packs which are adequate to transfer the construction loads. (4) All columns shall be evaluated by a...

2013-07-01

264

How to design baffle tray columns  

Microsoft Academic Search

As with packed columns, well-known heat transfer equations can be used to estimate mass transfer efficiencies for baffle tray columns. Other variables that can be calculated using this method include: flooding capacity, pressure drop, number of transfer units (NTUs) and the height equivalent to a theoretical plate (HETP). Gas-liquid contacting columns containing simple baffles have been used in hydrocarbon processing

Fair

1993-01-01

265

Contact structure for use in catalytic distillation  

DOEpatents

A method and apparatus for conducting catalytic chemical reactions and fractionation of the reaction mixture, comprising and feeding reactants into a distillation column reactor contracting said reactant in a liquid phase with a fixed bed catalyst in the form of a contact catalyst structure, consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

Jones, Jr., Edward M. (Friendswood, TX)

1985-01-01

266

Contact structure for use in catalytic distillation  

DOEpatents

A method is described for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor, contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column. 7 figs.

Jones, E.M. Jr.

1984-03-27

267

Contact structure for use in catalytic distillation  

DOEpatents

A method for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catatlyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

Jones, Jr., Edward M. (Friendswood, TX)

1984-01-01

268

Contact structure for use in catalytic distillation  

DOEpatents

A method and apparatus are disclosed for conducting catalytic chemical reactions and fractionation of the reaction mixture, comprising and feeding reactants into a distillation column reactor contracting said reactant in a liquid phase with a fixed bed catalyst in the form of a contact catalyst structure, consisting of closed porous containers containing the catalyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column. 7 figs.

Jones, E.M. Jr.

1985-08-20

269

Aggregated models for integrated distillation systems  

SciTech Connect

In this work the authors present an aggregated representation for distillation columns that can be used in the synthesis of separation sequences with heat integration. A new aggregated model is first presented for the stripping and rectifying sections of individual distillation columns. This model is based on mass balances and equilibrium feasibility, expressed in terms of flows, inlet concentrations, and recoveries. The energy balance can then be decoupled from the mass balance, and the utilities can be calculated for each separation task. The proposed model is applied to three different superstructures: state task network, state equipment network, and an intermediate representation. The proposed model yields a lower bound to the vapor flow or to the total cost of the utilities. Performance of the different superstructure representations in terms of robustness and computational time is illustrated with several examples.

Caballero, J.A. [Univ. of Alicante (Spain). Dept. of Chemical Engineering] [Univ. of Alicante (Spain). Dept. of Chemical Engineering; Grossmann, I.E. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering] [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Chemical Engineering

1999-06-01

270

Packed Bed Reactor Experiment  

NASA Video Gallery

The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

271

Datalogging the Distillation Process.  

ERIC Educational Resources Information Center

Presents a distillation experiment that uses temperature sensors connected to a computer in place of thermometers, and enables the whole class to view the data on a monitor and interpret and discuss the data in real time. (JRH)

Soares, Allan; Creevy, Steven

1995-01-01

272

Vapor Compression Distillation Module.  

National Technical Information Service (NTIS)

A Vapor Compression Distillation (VCD) module was developed and evaluated as part of a Space Station Prototype (SSP) environmental control and life support system. The VCD module includes the waste tankage, pumps, post-treatment cells, automatic controls ...

P. P. Nuccio

1975-01-01

273

Well packing system  

Microsoft Academic Search

This patent describes a packing structure and method of packing which can be used in the wellbore of injection wells for the recovery of heavy oils, shale oils, and tars, and in well shafts for in-situ coal gasification. The packing can also be used in the wellbore of gas and light oil production wells. The packing is used to provide

Drnevich

1990-01-01

274

Experimental and Numerical Investigation of Two Dimensional CO2 Adsorption/Desorption in Packed Sorption Beds under Non-Ideal Flows  

NASA Technical Reports Server (NTRS)

The experimental results of CO2 adsorption and desorption in a packed column indicated that the concentration wave front at the center of the packed column differs from those which are close to the wall of column filled with adsorbent material even though the ratio of column diameter to the particle size is greater than 20. The comparison of the experimental results with one dimensional model of packed column shows that in order to simulate the average breakthrough in a packed column a two dimensional (radial and axial) model of packed column is needed. In this paper the mathematical model of a non-slip flow through a packed column with 2 inches in diameter and 18 inches in length filled with 5A zeolite pellets is presented. The comparison of experimental results of CO2 absorption and desorption for the mixed and central breakthrough of the packed column with numerical results is also presented.

Mohamadinejad, H.; Knox, J. C.; Smith, J. E.; Croomes, Scott (Technical Monitor)

2001-01-01

275

40 CFR 721.4500 - Isopropylamine distillation residues and ethylamine distillation residues.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Isopropylamine distillation residues and ethylamine distillation residues. 721.4500 Section 721...Substances § 721.4500 Isopropylamine distillation residues and ethylamine distillation...

2013-07-01

276

40 CFR 721.4500 - Isopropylamine distillation residues and ethylamine distillation residues.  

Code of Federal Regulations, 2010 CFR

... 2009-07-01 false Isopropylamine distillation residues and ethylamine distillation residues. 721.4500 Section 721...Substances § 721.4500 Isopropylamine distillation residues and ethylamine distillation...

2009-07-01

277

40 CFR 721.4500 - Isopropylamine distillation residues and ethylamine distillation residues.  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Isopropylamine distillation residues and ethylamine distillation residues. 721.4500 Section 721...Substances § 721.4500 Isopropylamine distillation residues and ethylamine distillation...

2010-07-01

278

Winogradsky Columns  

NSDL National Science Digital Library

This is an exercise about Winogradsky Columns with emphasis placed on the formation and properties of microbial biofilms. It includes background reference material, a field/lab exercise, and several applications. Applications include methods for sampling column layers and a description of how to measure the electro-chemical gradient that develops within the column. Scientific illustrations and images are included as visual references.

Lennox, John; State, Penn

279

APPLICATION OF BINARY PACKING FOR STARCH SEPARATION BY HYDRODYNAMIC CHROMATOGRAPHY  

Microsoft Academic Search

Columns packed with commercial glass beads of 5 and 19 microns average diameter and binary mixtures with finest fraction of 5 micron (30 % volume fraction of the mixture) were used to analyse starch by hydrodynamic chromatography (HDC). Experiments were carried out at 3 and 15 ºC. The observed resolution increased with the application of binary packing as compared with

M. Mota; J. A. Teixeira; R. Dias; A. Yelshin

2008-01-01

280

Ore Separation in a Packed-Fluidized Bed.  

National Technical Information Service (NTIS)

The segregating tendency of particles of differing densities in a gas-fluidized packed bed was applied to ore separation. Two columns (5- and 3-cm. i.d.) filled with cylindrical screen packing were used to study the upgrading of a germanium ore and two ir...

C. E. Capes J. P. Sutherland

1965-01-01

281

APPLICATION OF CAPILLARY SUPERCRITICAL FLUID CHROMATOGRAPHY TO THE ANALYSIS OF A MIDDLE DISTILLATE FUEL  

EPA Science Inventory

The paper describes the application of capillary supercritical fluid chromatography (SFC) to the analysis of a middle distillate fuel. Small diameter (50 micrometer i.d.) fused silica capillary columns coated with crosslinked 50% phenyl polymethylsiloxane provided high separation...

282

Reactive Distillation and Air Stripping Processes for Water Recycling and Trace Contaminant Control  

NASA Technical Reports Server (NTRS)

Reactive distillation designs are considered to reduce the presence of volatile organic compounds in the purified water. Reactive distillation integrates a reactor with a distillation column. A review of the literature in this field has revealed a variety of functional reactive columns in industry. Wastewater may be purified by a combination of a reactor and a distiller (e.g., the EWRS or VPCAR concepts) or, in principle, through a design which integrates the reactor with the distiller. A review of the literature in reactive distillation has identified some different designs in such combinations of reactor and distiller. An evaluation of reactive distillation and reactive air stripping is presented with regards to the reduction of volatile organic compounds in the contaminated water and air. Among the methods presented, an architecture is presented for the evaluation of the simultaneous oxidation of organics in air and water. These and other designs are presented in light of potential improvements in power consumptions and air and water purities for architectures which include catalytic activity integrated into the water processor. In particular, catalytic oxidation of organics may be useful as a tool to remove contaminants that more traditional distillation and/or air stripping columns may not remove. A review of the current leading edge at the commercial level and at the research frontier in catalytically active materials is presented. Themes and directions from the engineering developments in catalyst design are presented conceptually in light of developments in the nanoscale chemistry of a variety of catalyst materials.

Boul, Peter J.; Lange, Kevin E.; Conger, Bruce; Anderson, Molly

2009-01-01

283

Israelachvili Packing factor  

NSDL National Science Digital Library

Israelachvili Packing factor. The geometry of associated structures depends upon "packing" properties of the molecule: the optimal area of the head group, a0, volume of the chain, V, and the critical length of the tether, lc.

Iacovella, Christopher R.

2006-08-02

284

Oil distilling system  

Microsoft Academic Search

A method of distilling hydrocarbon oil is described which comprises burning a combustible mixture while submerged in the oil, effecting direct contact of the products of combustion with the oil, and controlling the temperature resulting from the combustion by diluting the combustible mixture with an inert gas prior to its introduction into the oil.

Hill

1932-01-01

285

Distilling entanglement from Fermions  

Microsoft Academic Search

Since Fermions are based on anti-commutation relations, their entanglement can not be studied in the usual way, such that the available theory has to be modified appropriately. Recent publications consider in particular the structure of separable and of maximally entangled states. In this talk we want to discuss local operations and entanglement distillation from bipartite, Fermionic systems. To this end

Michael Keyl

2008-01-01

286

Distill Salt Water  

NSDL National Science Digital Library

In this activity, conduct an experiment to make freshwater out of saltwater. First, make saltwater and then seal it and place it in the Sun for a couple of hours or even a whole day. This solar still will distill, or purify, the water. Use this activity to explore water purification and evaporation. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-01-17

287

Tritium Attenuation by Distillation  

SciTech Connect

The objective of this study was to determine how a 100 Area distillation system could be used to reduce to a satisfactory low value the tritium content of the dilute moderator produced in the 100 Area stills, and whether such a tritium attenuator would have sufficient capacity to process all this material before it is sent to the 400 Area for reprocessing.

Wittman, N.E.

2001-07-31

288

Topological quantum distillation.  

PubMed

We construct a class of topological quantum codes to perform quantum entanglement distillation. These codes implement the whole Clifford group of unitary operations in a fully topological manner and without selective addressing of qubits. This allows us to extend their application also to quantum teleportation, dense coding, and computation with magic states. PMID:17155532

Bombin, H; Martin-Delgado, M A

2006-11-01

289

Qutrit magic state distillation  

Microsoft Academic Search

Magic state distillation (MSD) is a purification protocol that plays an important role in fault-tolerant quantum computation. Repeated iteration of the steps of an MSD protocol generates pure single non-stabilizer states, or magic states, from multiple copies of a mixed resource state using stabilizer operations only. Thus mixed resource states promote the stabilizer operations to full universality. MSD was introduced

Hussain Anwar; Earl T Campbell; Dan E Browne

2012-01-01

290

The production of diacetone alcohol with catalytic distillation  

Microsoft Academic Search

The aldol condensation of acetone to diacetone alcohol (DAA) has been accomplished with catalytic distillation (CD). A steady-state, rate-based model for the reaction zone of the CD column is developed and fitted to the experimental data which were presented in Part I of this paper. This model is unique in that it considers external mass transfer between the liquid phase

G. G. Podrebarac; F. T. T. Ng; G. L. Rempel

1998-01-01

291

Feasibility studies for batch extractive distillation with a light entrainer  

Microsoft Academic Search

Our former method for the assessment of the feasibility of batch extractive distillation (usually performed in a rectifier with a heavy entrainer) was extended to the case where a light entrainer is fed continuously into a rectifier or a stripper. The method is based on the calculation of the vessel path and possible composition profiles of the column sections. The

P. Lang; Z. Lelkes; M. Otterbein; B. Benadda; G. Modla

1999-01-01

292

Distillation of hydrogen isotopes for polarized HD targets  

NASA Astrophysics Data System (ADS)

We have developed a new cryogenic distillation system to purify Hydrogen-Deuteride (HD) gas for polarized HD targets in LEPS experiments at SPring-8. A small amount of ortho-H 2 ( ˜0.01%) in the HD gas plays an important role in efficiently polarizing the HD target. Since there are 1-5% impurities of H 2 and D 2 in commercially available HD gases, it is necessary to purify the HD gas up to ˜99.99%. The distillation system is equipped with a cryogenic distillation unit filled with many small stainless steel cells called "Heli-pack". The distillation unit consists of a condenser part, a rectification part, and a reboiler part. The unit is kept at the temperature of 17-21 K. The Heli-pack has a large surface area that makes a good contact between gases and liquids. An amount of 5.2 mol of commercial HD gas is fed into the distillation unit. Three trials were carried out to purify the HD gas by changing temperatures (17.5 K and 20.5 K) and gas extraction speeds (1.3 ml/min and 5.2 ml/min). The extracted gas was analyzed using a gas analyzer system combining a quadrupole mass spectrometer with a gas chromatograph. One mol of HD gas with a purity better than 99.99% has been successfully obtained for the first time. The effective NTP (Number of Theoretical Plates), which is an indication of the distillation performances, is obtained to be 37.2±0.6. This value is in good agreement with a designed value of 37.9. The HD target is expected to be efficiently polarized under a well-controlled condition by adding an optimal amount of ortho-H 2 to the purified HD gas.

Ohta, T.; Bouchigny, S.; Didelez, J.-P.; Fujiwara, M.; Fukuda, K.; Kohri, H.; Kunimatsu, T.; Morisaki, C.; Ono, S.; Rouillé, G.; Tanaka, M.; Ueda, K.; Uraki, M.; Utsuro, M.; Wang, S. Y.; Yosoi, M.

2012-02-01

293

Modified CelliGen-packed bed bioreactors for hybridoma cell cultures  

Microsoft Academic Search

This study describes two packed bed bioreactor configurations which were used to culture a mouse-mouse hybridoma cell line\\u000a (ATCC HB-57) which produces an IgG1 monoclonal antibody. The first configuration consists of a packed column which is continuously perfused by recirculating\\u000a oxygenated media through the column. In the second configuration, the packed bed is contained within a stationary basket which\\u000a is

Guozheng Wang; Wenying Zhang; Corey Jacklin; David Freedman; Lee Eppstein; Avinoam Kadouri

1992-01-01

294

Leaf Pack Network  

NSDL National Science Digital Library

The Leaf Pack Network (LPN) is a network of teachers and students investigating their local stream ecosystems by participating in the leaf pack experiment, which involves creating an artificial leaf pack (dry leaves in a mesh bag), immersing it in a stream for 3-4 weeks, and examining it for signs of aquatic insects as indicators of stream health. Participating classrooms share their data through the internet. This activity highlights the connection between streamside forests and the ecology of rivers and streams.

295

Method for making a non-extractable stationary phase of polymer within a capillary column  

DOEpatents

A method for coating interior capillary column surfaces, or packing material of a packed column, used for gas chromatography, with a stationary polymer phase that is cross-linked by exposing it to a low-temperature plasma that is uniformly distributed over the column or packing material for a predetermined period of time to effect the desired degree of cross-linking of the coating.

Springston, Stephen R. (Middle Island, NY)

1990-01-01

296

Method for making a non-extractable stationary phase of polymer within a capillary column  

DOEpatents

A method is described for coating interior capillary column surfaces, or packing material of a packed column, used for gas chromatography, with a stationary polymer phase that is cross-linked by exposing it to a low-temperature plasma that is uniformly distributed over the column or packing material for a predetermined period of time to effect the desired degree of cross-linking of the coating. 7 figs.

Springston, S.R.

1990-10-30

297

Distillation column configurations in ammonia–water absorption refrigeration systems  

Microsoft Academic Search

In ammonia–water absorption refrigeration systems a purification process to reduce the water content in the vapour leaving the generator is required. During this process the water content in the vapour must be reduced to a minimum, otherwise it tends to accumulate in the evaporator and strongly deteriorates the efficiency of the system. The vapour purification can be carried out by

José Fernández-Seara; Jaime Sieres; Manuel Vázquez

2003-01-01

298

An Analogy between Fractional Distillation and Separating Physically Fit and Physically Less Fit Persons  

NASA Astrophysics Data System (ADS)

Separating two liquids in a fractional distillation column on the basis of their difference in boiling points is analogous to separating a group of people on the basis of their physical fitness by making them climb a flight of stairs. Several aspects of this unit operation such as column height, flooding, and reflux ratio are explained with the help of this analogy.

Mukesh, Doble

2001-02-01

299

Iterative packing for demand matching and sparse packing.  

SciTech Connect

The main result we will present is a 2k-approximation algorithm for the following 'k-hypergraph demand matching' problem: given a set system with sets of size <=k, where sets have profits & demands and vertices have capacities, find a max-profit subsystem whose demands do not exceed the capacities. The main tool is an iterative way to explicitly build a decomposition of the fractional optimum as 2k times a convex combination of integral solutions. If time permits we'll also show how the approach can be extended to a 3-approximation for 2-column sparse packing. The second result is tight w.r.t the integrality gap, and the first is near-tight as a gap lower bound of 2(k-1+1/k) is known.

Parekh, Ojas

2010-11-01

300

Properties of monolithic silica columns for HPLC.  

PubMed

Monolithic silica columns and their use in high peak-capacity HPLC separations are reviewed. Monolithic silica columns can potentially provide higher overall performance than particle-packed columns based on the variable external porosity and variable through-pore size/skeleton size ratios. The high permeability of monolithic silica columns resulting from the high porosity is shown to be advantageous to generate large numbers of theoretical plates with long capillary columns. High permeability together with the high stability of the network structures of silica allows their use in high-speed separations required for a second-dimension column in two dimensional HPLC. Disadvantages of monolithic silica columns are also described. PMID:16760589

Kobayashi, Hiroshi; Ikegami, Tohru; Kimura, Hiroshi; Hara, Takeshi; Tokuda, Daisuke; Tanaka, Nobuo

2006-04-01

301

Systems and methods for reactive distillation with recirculation of light components  

DOEpatents

Systems and methods for producing gas-to-liquids products using reactive distillation are provided. The method for producing gas-to-liquids products can include reacting a feedstock in a column having a distillation zone and a reaction zone to provide a bottoms stream and an overhead stream. A first portion of the overhead stream can be recycled to the column at the top of the reaction zone and second portion of the overhead stream can be recycled to the column at the bottom of the reaction zone.

Stickney, Michael J. (Nassau Bay, TX) [Nassau Bay, TX; Jones, Jr., Edward M. (Friendswood, TX)

2011-07-26

302

Fabrication and investigation of electrochromatographic columns with a simplex configuration.  

PubMed

Duplex capillary columns with a packed and an open section are widely used in electrochromatography (CEC). The duplex column configuration leads to non-uniform voltage drop, electrical field distribution and separation performance. It also adds to the complexity in understanding and optimizing electrochromatographic process. In this study, we introduced a simplex column configuration based on single particle fritting technology. The new column configuration has an essentially uniform packed bed through the entire column length, with only 1mm length left unpacked serving as the optical detection window. The study shows that a simplex column has higher separation efficiency than a duplex column, especially at the high voltage range, due to the consistent distribution of electrical field over the column length. In comparison to the duplex column, the simplex column presented a lower flow rate at the same applied voltage, suggesting that an open section may support a higher speed than a packed section. In practice, the long and short ends of the simplex column could be used as independent CEC columns respectively. This "two-in-one" bi-functional column configuration provided extra flexibilities in selecting and optimizing electrochromatographic conditions. PMID:24856906

Liu, Qing; Yang, Lijun; Wang, Qiuquan; Zhang, Bo

2014-07-01

303

Standards Column  

Microsoft Academic Search

In this column we will review the status of the project to revise ISO 8423:1991 and the status of development of ISO 10019 on the use of consultants to help develop management systems. We will look at the ISO process for periodic systematic review of standards and look at the status of some of the recent and current reviews in

John West

2008-01-01

304

Column Chromatography  

NSDL National Science Digital Library

In this activity, learners separate the components of Gatorade using a home-made affinity column. In doing so, learners model the basic principle of affinity chromatography, a technique used to purify chemicals as well as bio-pharmaceuticals and petroleum products. This resource contains information about affinity chromatography and polarity.

Yu, Julie

2007-01-01

305

Present status of solar distillation  

Microsoft Academic Search

In this communication an attempt has been made to review, in brief, work on solar distillation, its present status in the world today and its future perspective. The review also includes water sources, water demand, availability of potable water and purification methods including the state of art and historical background. The classification of distillation units has been done on the

G. N. Tiwari; H. N. Singh; Rajesh Tripathi

2003-01-01

306

Determination of trace amounts of nitrogen in uranium based samples by ion chromatography (IC) without Kjeldahl distillation  

Microsoft Academic Search

A simple, sensitive and fast ion chromatographic (IC) method with suppressed conductivity detection is described for the determination of traces of nitrogen in uranium based fuel materials. Initially a method was developed to determine nitrogen as NH4+ using cation exchange column after matrix separation by Kjeldahl distillation. The method was then improved by eliminating this distillation. Matrix separation after sample

Poonam Verma; Ramakant K. Rastogi; Karanam L. Ramakumar

2007-01-01

307

Graphitic packing removal tool  

DOEpatents

Graphitic packing removal tools for removal of the seal rings in one piece. he packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal.

Meyers, Kurt Edward (Avella, PA); Kolsun, George J. (Pittsburgh, PA)

1997-01-01

308

Graphitic packing removal tool  

DOEpatents

Graphitic packing removal tools for removal of the seal rings in one piece are disclosed. The packing removal tool has a cylindrical base ring the same size as the packing ring with a surface finish, perforations, knurling or threads for adhesion to the seal ring. Elongated leg shanks are mounted axially along the circumferential center. A slit or slits permit insertion around shafts. A removal tool follower stabilizes the upper portion of the legs to allow a spanner wrench to be used for insertion and removal. 5 figs.

Meyers, K.E.; Kolsun, G.J.

1997-11-11

309

Solar energy: Packing heat  

NASA Astrophysics Data System (ADS)

Nanoscopic templates functionalized with light-reactive chromophores could ultimately be used to store solar energy and later release it as heat. Now, it has been shown that packing the chromophores together increases both storage capacity and lifetime.

Neale, Nathan R.

2014-05-01

310

Packing Peanut Properties  

NSDL National Science Digital Library

Students work with various types of packing peanuts to investigate states of matter and chemical and physical changes. One of the activities involves making slime. The activities can easily be modified for students with learning disabilities.

Hall, Dori; Hall, Sue

2002-02-02

311

Tiber winding pack design  

SciTech Connect

A preliminary winding pack design was performed with the goal of showing feasibility of producing 10-T maximum field with a pack current density of 40 A.mm/sup -2/ while accepting 2.7 kW per coil nuclear heating. A cable-in-conduit conductor design (CIC), reported at the 6th Topical Meeting on the Technology of Fusion Energy, was based on several key issues.

Miller, J.R.

1985-08-19

312

Standards Column  

Microsoft Academic Search

In this column we will cover the Final Draft International Standard (FDIS) for ISO 9001:2008 and the rules for transition of accredited certifications to ISO 9001:2000 to the new edition. We will also review the status of the work of a new ISO\\/TC 69 Subcommittee developing ISO documents to support Six Sigma implementation. Finally we will look at the status

Jack E. West

2008-01-01

313

Standards Column  

Microsoft Academic Search

In this column we announce publication in November 2008 of ISO 9001:2008, the latest edition of the world's most popular standard. We will also discuss the introduction and support packages available from ISO\\/TC 176 for ISO 9001:2008. The forthcoming third edition of ISO\\/TS 16949, the automotive industry sector specific QMS document based on ISO 9001:2008, will be discussed. We will

Jack E. West

2009-01-01

314

Vapor–Liquid Equilibrium of Ethanol–Water System in the Presence of Molecular Sieves  

Microsoft Academic Search

Adsorptive distillation is a new process to separate liquid mixtures in a packed distillation column. It depends on using active packing material instead of inert packing material in a packed distillation column. The active packing material can affect the intermolecular forces among the system components and thus alter its vapor–liquid equilibrium (VLE). The VLE of the ethanol–water system at 1

FAHMI A. ABU AL-RUB; FAWZI A. BANAT; RAMI JUMAH

1999-01-01

315

Packing and stability of geometrically cohesive granular media  

NASA Astrophysics Data System (ADS)

Granular particles with concave shapes may entangle with neighboring particles creating an effective cohesion controlled by particle geometry. We study the packing and stability of vertical columns formed from geometrically cohesive u-shaped particles (staples) of varying barb length, l. We prepare cohesive columns by packing particles in a confining cylindrical tube under vertical vibration at fixed frequency of f = 30 Hz and peak acceleration (in units of g) of ?= 2. The initial and final volume fraction vary with l and volume fraction increases for decreasing l. Once packed, the tube is removed and columns are subjected to vertical vibration at fixed f and variable ?. We monitor column height, h(t), during collapse and find that h(t) is described by a stretched exponential h(t)/h0= [-(t?)^?]. The characteristic collapse time, ?, is governed by an Arrhenius law with ?= ?0(?0/?) where ?0 is a measure of the column's resistance to collapse. We find that ?0 is a non-monotonic function of l and exhibits a maximum at intermediate l. We explain this effect through a model considering packing and entanglement.

Gravish, Nick; Franklin, Scott V.; Hu, David L.; Goldman, Daniel I.

2011-11-01

316

Hybrid Membrane-Cryogenic Distillation Air Separation Process for Oxygen Production  

Microsoft Academic Search

A hybrid air separation process for oxygen production uses a membrane gas permeator with bypass to increase the oxygen concentration of the feed to 23.5% before the cryogenic distillation plant. A 23.5% limit on oxygen is required to avoid use of more expensive construction materials. By pre-concentrating the oxygen, the feed flowrate to the compressor, heat exchangers and distillation column

Phillip C. Wankat; Kyle P. Kostroski

2011-01-01

317

Contexts for Column Addition and Subtraction  

ERIC Educational Resources Information Center

In this article, the authors discuss their approach to column addition and subtraction algorithms. Adapting an original idea of Paul Cobb and Erna Yackel's from "A Contextual Investigation of Three-Digit Addition and Subtraction" related to packing and unpacking candy in a candy factory, the authors provided an analogous context by designing…

Lopez Fernandez, Jorge M.; Velazquez Estrella, Aileen

2011-01-01

318

Study of electroosmotic flow in packed capillary columns.  

PubMed

The aim of the work was to find the relationship between the structure of the stationary phase and the velocity of the electroosmotic flow (EOF) that it can generate. The attention was paid to the dependence of the electroosmotic mobility (microEOF) on such parameters as: (i) coverage density of a series of specially synthesized C18 stationary phases with/without end-capping, with monomeric/polymeric architecture; (ii) the length of the alkyl chain in the alkylamide (AP) bonded phase (the phases studied were AP with: C1, C5, C6, C7, C8, C12 and C18 alkyl chains) and the effect of the presence of amide and residual amine groups; (iii) the effect of the mobile phase composition on the EOF; (iv) the effect of pH on the EOF. The obtained results have shown that there is no direct relationship between silanol activity (Galushko test) and electroosmotic mobility for C18 phases. The deterioration of the EOF has been observed for AP phases at high pH values. This effect has been attributed to the presence of hydrolytic pillow, which is connected with the sorption of water from hydro-organic mobile phases. PMID:15065790

Szumski, Micha?; Buszewski, Bogus?aw

2004-04-01

319

Theory of random packings  

NASA Astrophysics Data System (ADS)

We review a recently proposed theory of random packings. We describe the volume fluctuations in jammed matter through a volume function, amenable to analytical and numerical calculations. We combine an extended statistical mechanics approach `a la Edwards' (where the role traditionally played by the energy and temperature in thermal systems is substituted by the volume and compactivity) with a constraint on mechanical stability imposed by the isostatic condition. We show how such approaches can bring results that can be compared to experiments and allow for an exploitation of the statistical mechanics framework. The key result is the use of a relation between the local Voronoi volume of the constituent grains and the number of neighbors in contact that permits a simple combination of the two approaches to develop a theory of random packings. We predict the density of random loose packing (RLP) and random close packing (RCP) in close agreement with experiments and develop a phase diagram of jammed matter that provides a unifying view of the disordered hard sphere packing problem and further shedding light on a diverse spectrum of data, including the RLP state. Theoretical results are well reproduced by numerical simulations that confirm the essential role played by friction in determining both the RLP and RCP limits. Finally we present an extended discussion on the existence of geometrical and mechanical coordination numbers and how to measure both quantities in experiments and computer simulations.

Song, Chaoming; Wang, Ping; Makse, Hernán A.

2010-05-01

320

[Nasal packing and stenting].  

PubMed

Despite nasal packing is not necessary after functional endoscopic sinus surgery according to modern surgical techniques, nasal packing is a necessary tool in ENT. Therefore the state of the art regarding indications, benefit and risk of nasal packing and stents are given. In endonasal surgery only those conventional nasal packing materials should be used--if necessary--which have a smooth surface and minimize mucosal damage, potential worsening of wound healing and negative impact on patient comfort. Modern FESS implicates modern types of nasal packing, which leave the old concept of performing pressure and occupying space. So called hemostatic/resorbable materials are a first step in this direction. But they are critical, because these materials cause increased synechiae and sometimes foreign body reactions because of incorporation into the mucosa. Occlusion of the nose via simple taping of the nasal entrance is a simple and very effective method to create a moist environment to optimize endonasal wound healing or management of a dry nose. Stenting of the frontal sinus is only recommended if it is not possible to realize a sufficiently wide, physiologically formed and in large areas with mucosa covered frontal sinus outflow tract. PMID:19353455

Weber, R K

2009-05-01

321

Distillation process using microchannel technology  

DOEpatents

The disclosed invention relates to a distillation process for separating two or more components having different volatilities from a liquid mixture containing the components. The process employs microchannel technology for effecting the distillation and is particularly suitable for conducting difficult separations, such as the separation of ethane from ethylene, wherein the individual components are characterized by having volatilities that are very close to one another.

Tonkovich, Anna Lee (Dublin, OH); Simmons, Wayne W. (Dublin, OH); Silva, Laura J. (Dublin, OH); Qiu, Dongming (Carbondale, IL); Perry, Steven T. (Galloway, OH); Yuschak, Thomas (Dublin, OH); Hickey, Thomas P. (Dublin, OH); Arora, Ravi (Dublin, OH); Smith, Amanda (Galloway, OH); Litt, Robert Dwayne (Westerville, OH); Neagle, Paul (Westerville, OH)

2009-11-03

322

New Bounds for Multi-Dimensional Packing.  

National Technical Information Service (NTIS)

New upper and lower bounds are presented for a multi-dimensional generalization of bin packing called box packing. Several variants of this problem, including bounded space box packing, square packing, variable sized box packing and resource augmented box...

R. Van Stee S. Seiden

2001-01-01

323

DESIGN SCALE-UP SUITABILITY FOR AIR-STRIPPING COLUMNS  

EPA Science Inventory

Air-stripping in a packed column is sometimes used to remove volatile organic compounds from contaminated water supplies. Since the design engineer frequently uses data from a pilot air-stripping column to design a full-scale system, the suitability of such design scale-up was in...

324

Preparation and characterization of spherical polymer packings from polybutadiene for size-exclusion chromatography.  

PubMed

Porous polymer spherical particles for column packings in nonaqueous size-exclusion chromatography (SEC) were prepared from 1,2-syndiotactic polybutadiene by suspension and evaporation method. The polymer microbeads obtained were crosslinked by radical reaction between 2-vinyl groups in polybutadiene with ultraviolet radiation, to render them insoluble. These microbeads have wider chromatographic separation width than polystyrene column packings. In addition, the polybutadiene microbeads did not show the excessive retention observed with commercial polystyrene columns for polycyclic aromatic compounds. Therefore, a close correlation between the elution volume and M, for polycyclic aromatic compounds was observed with polybutadiene microbeads columns. PMID:16035360

Nagaoka, S; Satoh, T; Sakamoto, K; Ihara, H

2005-08-01

325

Non-planar microfabricated gas chromatography column  

DOEpatents

A non-planar microfabricated gas chromatography column comprises a planar substrate having a plurality of through holes, a top lid and a bottom lid bonded to opposite surfaces of the planar substrate, and inlet and outlet ports for injection of a sample gas and elution of separated analytes. A plurality of such planar substrates can be aligned and stacked to provide a longer column length having a small footprint. Furthermore, two or more separate channels can enable multi-channel or multi-dimensional gas chromatography. The through holes preferably have a circular cross section and can be coated with a stationary phase material or packed with a porous packing material. Importantly, uniform stationary phase coatings can be obtained and band broadening can be minimized with the circular channels. A heating or cooling element can be disposed on at least one of the lids to enable temperature programming of the column.

Lewis, Patrick R. (Albuquerque, NM); Wheeler, David R. (Albuquerque, NM)

2007-09-25

326

Separation of n-propanol from allyl alcohol by extractive distillation  

SciTech Connect

This patent describes a method for recovering n-propanol from a mixture of n-propanol and allyl alcohol which comprises distilling a mixture of n-propanol and allyl alcohol in a rectification column in the presence of about one part of extractive agent per part of n-propanol-allyl alocohol mixture, recovering n-propanol as overhead product, obtaining the allyl alcohol and the extractive agent from the stillpot, separating the allyl alchohol from the extractive agent by distillation in another rectification column, wherein the extractive agent comprises at least one member of the group consisting of acetamide, N,N-dimethylacetamide, adiponitrile, dimethylformamide, dimethylsulfoxide and sulfolane.

Berg, L.; Vosburgh, M.G.

1986-07-22

327

Distillation and Air Stripping Designs for the Lunar Surface  

NASA Technical Reports Server (NTRS)

Air stripping and distillation are two different gravity-based methods, which may be applied to the purification of wastewater on the lunar base. These gravity-based solutions to water processing are robust physical separation techniques, which may be advantageous to many other techniques for their simplicity in design and operation. The two techniques can be used in conjunction with each other to obtain high purity water. The components and feed compositions for modeling waste water streams are presented in conjunction with the Aspen property system for traditional stage distillation models and air stripping models. While the individual components for each of the waste streams will vary naturally within certain bounds, an analog model for waste water processing is suggested based on typical concentration ranges for these components. Target purity levels for the for recycled water are determined for each individual component based on NASA s required maximum contaminant levels for potable water Distillation processes are modeled separately and in tandem with air stripping to demonstrate the potential effectiveness and utility of these methods in recycling wastewater on the Moon. Optimum parameters such as reflux ratio, feed stage location, and processing rates are determined with respect to the power consumption of the process. Multistage distillation is evaluated for components in wastewater to determine the minimum number of stages necessary for each of 65 components in humidity condensate and urine wastewater mixed streams. Components of the wastewater streams are ranked by Henry s Law Constant and the suitability of air stripping in the purification of wastewater in terms of component removal is evaluated. Scaling factors for distillation and air stripping columns are presented to account for the difference in the lunar gravitation environment. Commercially available distillation and air stripping units which are considered suitable for Exploration Life Support are presented. The advantages to the various designs are summarized with respect to water purity levels, power consumption, and processing rates.

Boul, Peter J.; Lange, Kevin E.; Conger, Bruce; Anderson, Molly

2009-01-01

328

Bulk stress distributions in the pore space of sphere-packed beds under Darcy flow conditions  

NASA Astrophysics Data System (ADS)

In this paper, bulk stress distributions in the pore space of columns packed with spheres are numerically computed with lattice Boltzmann simulations. Three different ideally packed and one randomly packed configuration of the columns are considered under Darcy flow conditions. The stress distributions change when the packing type changes. In the Darcy regime, the normalized stress distribution for a particular packing type is independent of the pressure difference that drives the flow and presents a common pattern. The three parameter (3P) log-normal distribution is found to describe the stress distributions in the randomly packed beds within statistical accuracy. In addition, the 3P log-normal distribution is still valid when highly porous scaffold geometries rather than sphere beds are examined. It is also shown that the 3P log-normal distribution can describe the bulk stress distribution in consolidated reservoir rocks like Berea sandstone.

Pham, Ngoc H.; Voronov, Roman S.; Tummala, Naga Rajesh; Papavassiliou, Dimitrios V.

2014-03-01

329

Bulk stress distributions in the pore space of sphere-packed beds under Darcy flow conditions.  

PubMed

In this paper, bulk stress distributions in the pore space of columns packed with spheres are numerically computed with lattice Boltzmann simulations. Three different ideally packed and one randomly packed configuration of the columns are considered under Darcy flow conditions. The stress distributions change when the packing type changes. In the Darcy regime, the normalized stress distribution for a particular packing type is independent of the pressure difference that drives the flow and presents a common pattern. The three parameter (3P) log-normal distribution is found to describe the stress distributions in the randomly packed beds within statistical accuracy. In addition, the 3P log-normal distribution is still valid when highly porous scaffold geometries rather than sphere beds are examined. It is also shown that the 3P log-normal distribution can describe the bulk stress distribution in consolidated reservoir rocks like Berea sandstone. PMID:24730946

Pham, Ngoc H; Voronov, Roman S; Tummala, Naga Rajesh; Papavassiliou, Dimitrios V

2014-03-01

330

Gravel pack method  

Microsoft Academic Search

This completion method can be performed in the following sequence: (1) deforming the formation by injecting a fluid therein to form a cavity adjacent the well bore; and (2) pressure packing the cavity with an aggregate to further displace the formation outward, the aggregate being graded to form an outer sand exclusion zone and an inner high permeability zone. In

D. B. Wood; O. M. Kiel

1972-01-01

331

Packing Steiner trees  

Microsoft Academic Search

The Steiner packing problem is to find the maximum number of edge-disjoint subgraphs of a given graph G that connect a given set of required points S. This problem is motivated by practical applications in VLSI- layout and broadcasting, as well as theoretical reasons. In this paper, we study this problem and present an algorithm with an asymptotic approximation factor

Kamal Jain; Mohammad Mahdian; Mohammad R. Salavatipour

2003-01-01

332

Packing Directed Circuits Fractionally  

Microsoft Academic Search

LetG be a digraph, and letk=1, such that no “fractional” packing of directed circuits ofG has value >k, when every vertex is given “capacity” 1. We prove there is a set ofO (k logk logk) vertices meeting all directed circuits ofG.

Paul D. Seymour

1995-01-01

333

Find Your Pack  

NSDL National Science Digital Library

This activity introduces learners to wolf behavior and communication. Learners explore how wolves communicate with each other by using their sense of smell to identify members of their "pack." Activity also includes suggestions for connecting this activity to a discussion of how habitat loss can affect wolf populations.

Eduweb; Zoo, Minnesota

2012-01-01

334

Direct Contact Condensation of Immiscible Fluids in Packed Beds.  

National Technical Information Service (NTIS)

An experimental study of a film type direct contact heat exchanger using immiscible fluids is made. Laboratory experiments were conducted on a R-113-water system using both 2.5 cm Berl saddles and 3.2 cm spheres as packing, in a 14.6 cm diameter column. T...

K. D. Thomas H. R. Jacobs R. F. Boehm

1978-01-01

335

Phytosterol Distribution in Fractions Obtained from Processing of Distillers Dried Grains with Solubles Using Sieving and Elutriation  

Microsoft Academic Search

Cereal Chem. 84(6):626-630 In an earlier study, the combination of sieving and elutriation was effective in separating fiber from distillers dried grains with solubles (DDGS), the coproduct remaining after ethanol production from corn. To separate fiber, air was blown through sieve fractions in an elutriation column. Material carried by air to the top of the elutriation column was the lighter

Radhakrishnan Srinivasan; Robert A. Moreau; Kent D. Rausch; M. E. Tumbleson; Vijay Singh

2007-01-01

336

Comparison of advanced distillation control methods. Third annual report  

SciTech Connect

Detailed dynamic simulations of three industrial distillation columns (a propylene/propane splitter, a xylene/toluene column, and a depropanizer) have been used to study the issue of configuration selection for diagonal PI dual composition controls, feedforward from a feed composition analyzer, and decouplers. Auto Tune Variation (ATV) identification with on-line detuning for setpoint changes was used for tuning the diagonal proportional integral (PI) composition controls. In addition, robustness tests were conducted by inducting reboiler duty upsets. For single composition control, the (L, V) configuration was found to be best. For dual composition control, the optimum configuration changes from one column to another. Moreover, the use of analysis tools, such as RGA, appears to be of little value in identifying the optimum configuration for dual composition control. Using feedforward from a feed composition analyzer and using decouplers are shown to offer significant advantages for certain specific cases.

Riggs, J.B.

1997-07-01

337

Comparison of several packings for CO 2 chemical absorption in a packed column  

Microsoft Academic Search

CO2 capture and storage has gained widespread attention as an option for reducing greenhouse gas emissions. Chemical absorption and stripping of CO2 with hot potassium carbonate (K2CO3) solutions has been used in the past, however potassium carbonate solutions have a low CO2 absorption efficiency. Various techniques can be used to improve the absorption efficiency of this system with one option

Xinglei Zhao; Kathryn H. Smith; Michael A. Simioni; Wendy Tao; Sandra E. Kentish; Weiyang Fei; Geoffrey W. Stevens

2011-01-01

338

Hydrodynamic and mass transfer characteristic of a novel grid-structured plastic packing  

Microsoft Academic Search

The hydraulic and mass transfer characteristic of a novel grid-structured plastic packing is presented. The geometry of this\\u000a structured packings differ substantially from conventional corrugated structured packings resulting in an open structure which\\u000a enables a free exchange of vapour and liquid also in horizontal direction. The hydraulic performance has been measured by\\u000a air–water experiments in a 440 mm diameter column, the

Markus Lehner; Karin Hoffmann; Werner Geipel

2011-01-01

339

Feasibility of application of Thayer method to crude oil distillation  

SciTech Connect

The purpose of this report is to present the results of an evaluation of Victor R. Thayer's invention: ''Process and Apparatus for reducing the Energy Required to Separate Liquids by Distillation'', applied to crude oil distillation. In brief, Thayer claims that given a side draw-off pump-around on a distillation column for energy conservation, there would be a significant cost advantage by using on-tray heat exchange rather than external exchange. Preliminary cost estimates were made: external case, $1,091,000 +- 15%; on-tray case, $882,200 +- 20%; both values falling within the estimated uncertainity limits. Therefore, and coupled with much greated annual maintenance costs, a significant cost advantage of the on-tray system was not verified. The primary conclusion of the evaluation was that, in our opinion, the Thayer method will not be used for retrofit of crude oil distillation units, and probably will not be used in the design of new crude units. 12 refs.

Prengle, H.W. Jr.; Althaus, Y.E.

1987-07-31

340

Distillation Apparatuses Using Household Items  

NASA Astrophysics Data System (ADS)

A simple apparatus to demonstrate distillation principles can be very difficult to build without the specialty glassware found in chemistry laboratories. We have built inexpensive but effective distillation apparatuses from equipment that can be easily purchased at local department, grocery, or hardware stores. In one apparatus, colored water is heated to boiling and the condensed vapors drip into another container. In another apparatus, acetone is heated to boiling with hot water and the acetone vapors condense onto a Styrofoam cup. The Styrofoam cup is softened by the acetone and collapses. Rubbing alcohol can be used instead of acetone, but the cup is not softened and the boiling point is much higher. Both apparatuses can be used in a classroom. Both are simple, cost-effective ways of demonstrating distillation, evaporation, and condensation. They would be ideal to use in elementary and middle school classrooms when explaining these concepts.

Campanizzi, Danielle R. D.; Mason, Brenda; Hermann, Christine K. F.

1999-08-01

341

Optimal protocols for nonlocality distillation  

SciTech Connect

Forster et al. recently showed that weak nonlocality can be amplified by giving the first protocol that distills a class of nonlocal boxes (NLBs) [Phys. Rev. Lett. 102, 120401 (2009)] We first show that their protocol is optimal among all nonadaptive protocols. We next consider adaptive protocols. We show that the depth-2 protocol of Allcock et al. [Phys. Rev. A 80, 062107 (2009)] performs better than previously known adaptive depth-2 protocols for all symmetric NLBs. We present a depth-3 protocol that extends the known region of distillable NLBs. We give examples of NLBs for which each of the Forster et al., the Allcock et al., and our protocols perform best. The understanding we develop is that there is no single optimal protocol for NLB distillation. The choice of which protocol to use depends on the noise parameters for the NLB.

Hoeyer, Peter; Rashid, Jibran [Department of Computer Science, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, 2N 1N4 (Canada)

2010-10-15

342

Solar power water distillation unit  

NASA Astrophysics Data System (ADS)

Clean drinking water is the basic necessity for every human being, but about 1.1 billion people in the world lacked proper drinking water. There are many different types of water purification processes such as filtration, reverse osmosis, ultraviolet radiation, carbon absorption, but the most reliable processes are distillation and boiling. Water purification, such as distillation, is especially important in regions where water resources or tap water is not suitable for ingesting without boiling or chemical treatment. In design project It treats the water by combining different methods such as Filtration, Distillation and a technique called concentrated solar power (CSP). Distillation is literally the method seen in nature, whereby: the sun heats the water on the earth's surface, the water is turned into a vapor (evaporation) and rises, leaving contaminants behind, to form clouds. As the upper atmosphere drops in temperature the vapors cool and convert back to water to form water. In this project distillation is achieved by using a parabolic mirror which boils water at high temperature. Filtration is done by sand filter and carbon filter. First sand filter catches the sand particles and the carbon filter which has granules of active carbon is used to remove odor dissolved gases from water. This is the Pre-treatment of water. The filtered water is then collected in a water container at a focus of parabolic mirror where distillation process is done. Another important feature of designed project is the solar tracking of a parabolic mirror which increases the efficiency of a parabolic mirror [1],[2].

Hameed, Kamran; Muzammil Khan, Muhammad; Shahrukh Ateeq, Ijlal; Omair, Syed Muhammad; Ahmer, Muhammad; Wajid, Abdul

2013-06-01

343

Extended testing of compression distillation.  

NASA Technical Reports Server (NTRS)

During the past eight years, the NASA Manned Spacecraft Center has supported the development of an integrated water and waste management system which includes the compression distillation process for recovering useable water from urine, urinal flush water, humidity condensate, commode flush water, and concentrated wash water. This paper describes the design of the compression distillation unit, developed for this system, and the testing performed to demonstrate its reliability and performance. In addition, this paper summarizes the work performed on pretreatment and post-treatment processes, to assure the recovery of sterile potable water from urine and treated urinal flush water.

Bambenek, R. A.; Nuccio, P. P.

1972-01-01

344

Bounds for nonlocality distillation protocols  

SciTech Connect

Nonlocality can be quantified by the violation of a Bell inequality. Since this violation may be amplified by local operations, an alternative measure has been proposed--distillable nonlocality. The alternative measure is difficult to calculate exactly due to the double exponential growth of the parameter space. In this paper, we give a way to bound the distillable nonlocality of a resource by the solutions to a related optimization problem. Our upper bounds are exponentially easier to compute than the exact value and are shown to be meaningful in general and tight in some cases.

Forster, Manuel [Computer Science Department, ETH Zuerich, CH-8092 Zuerich (Switzerland)

2011-06-15

345

Solar distillation of sea water  

SciTech Connect

Indian coastal and fishing villages suffer from scarcity of potable water. Solar distillation could provide a solution to this problem by adopting the following criteria: (1) Integration of distillation and storage systems with the house design. (2) Public supply of sea water and a public drain pipe system to periodically drain away the concentrated brine. (3) Harvest and store rain water to tide over cloudy rainy periods. In India there has been a thrust towards centralized non-conventional energy systems. Decentralized non-conventional energy devices and centralized service support units may offer a better solution. 1 fig.

Subramanyam, S. (Kakatiya Institute of Technology and Science, Warangal (India))

1989-01-01

346

Compartmental modeling of high purity air separation columns  

Microsoft Academic Search

High purity distillation columns are critical unit operations in cryogenic air separation plants. The development of nonlinear control technology is motivated by the need to frequently change production rates in response to time varying utility costs. Detailed column models based on stage-by-stage balance equations are too complex to be incorporated directly into optimization-based strategies such as nonlinear model predictive control.

Shoujun Bian; Suabtragool Khowinij; Michael A. Henson; Paul Belanger; Lawrence Megan

2005-01-01

347

Compartmental modeling of high purity air separation columns  

Microsoft Academic Search

High purity distillation columns are critical unit operations in cryogenic air separation plants. The development of nonlinear control technology is motivated by the need to frequently change production rates in response to time varying utility costs. Detailed column models based on stage-by-stage balance equations are too complex to be incorporated directly into optimization-based strategies such as nonlinear model predictive control.

Shoujun Biana; Suabtragool Khowinij; Michael A. Henson; Paul Belanger; Lawrence Megan

348

Packing fraction of geometric random packings of discretely sized particles  

NASA Astrophysics Data System (ADS)

The packing fraction of geometric random packings of discretely sized particles is addressed in the present paper. In an earlier paper [Brouwers, Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.74.031309 74, 031309 (2006); Brouwers, Phys. Rev. EPLEEE81063-651X10.1103/PhysRevE.74.069901 74, 069901(E) (2006)], analytical solutions were presented for the packing fraction of polydisperse geometric packings for discretely sized particles with infinitely large size ratio and the packing of continuously sized particles. Here the packing of discretely sized particles with finite size ratio u is analyzed and compared with empirical data concerning five ternary geometric random close packings of spheres with a size ratio of 2, yielding good agreement.

Brouwers, H. J. H.

2011-10-01

349

Design and Synthesis Procedure for Homogeneous and Heterogeneous Azeotropic Distillations: Annual Report for Period March 1, 1986 to February 29, 1987.  

National Technical Information Service (NTIS)

The column sequencing problem for heterogeneous azeotropic distillation is investigated. It is shown that residue curve maps play an important role in interpreting the behavior of these systems. Classes of residue curve maps which give rise to feasible co...

M. F. Doherty

1986-01-01

350

Testing the equal-probability assumption of jammed particle packings  

NASA Astrophysics Data System (ADS)

The Edwards' entropy formalism provides a statistical mechanical framework for describing dense granular systems. In addition, experiments on vibrated granular columns and numerical simulations of quasi-static shear flow of dense granular systems have provided evidence that the Edwards' theory may accurately describe certain aspects of these systems. However, a fundamental assumption of the Edwards' description---that all mechanically stable (MS) granular packings at a given packing fraction are equally likely---has not been explicitly tested in dense granular systems. We investigate this assumption by generating all mechanically stable hard disk packings in small systems using a protocol in which we successively compress or decompress the system followed by energy minimization. We then apply quasi-static shear flow at fixed pressure to these MS packings to study the frequency with which MS packings occur during the shear flow. We find that the MS packings do not occur with equal probability during the shear flow, in fact, there is a significant reduction in the number of accessible MS packings at large shear strain. Thus, the Edwards' entropy formalism should be re-examined in light of our findings.

Gao, Guo-Jie; Blawzdziewicz, Jerzy; O'Hern, Corey

2007-03-01

351

Corrosion inhibition for distillation apparatus  

DOEpatents

Tower material corrosion in an atmospheric or sub-atmospheric distillation tower in a coal liquefaction process is reduced or eliminated by subjecting chloride-containing tray contents to an appropriate ion-exchange resin to remove chloride from such tray contents materials.

Baumert, Kenneth L. (Emmaus, PA); Sagues, Alberto A. (Lexington, KY); Davis, Burtron H. (Georgetown, KY); Schweighardt, Frank K. (Upper Macungie, PA)

1985-01-01

352

Purifying Aluminum by Vacuum Distillation  

NASA Technical Reports Server (NTRS)

Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

Du Fresne, E. R.

1985-01-01

353

Entanglement preservation by continuous distillation  

SciTech Connect

We study the two-qubit entanglement preservation for a system in the presence of independent thermal baths. We use a combination of filtering operations and distillation protocols as a series of frequent measurements on the system. It is shown that a small fraction of the total amount of available copies of the system preserves or even improves its initial entanglement during the evolution.

Mundarain, D. [Departmento de Fisica, Seccion de Fenomenos Opticos, Universidad Simon Bolivar, Apartado Postal 89000, Caracas 1080A (Venezuela, Bolivarian Republic of); Orszag, M. [Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)

2009-05-15

354

Distillation pinch points and more  

Microsoft Academic Search

Rising energy costs have spawned renewed interest in improving methodologies for the synthesis, design and\\/or retrofitting of separation processes. It is well known that energy use in many process industries is dominated by separation tasks—particularly distillation. In this work, the shortest stripping line approach recently proposed by Lucia, Amale, & Taylor (2006) is used to find minimum energy requirements in

Angelo Lucia; Amit Amale; Ross Taylor

2008-01-01

355

Catalytic dewaxing of middle distillates  

Microsoft Academic Search

The fractionation and stripping equipment of a middle distillate catalytic dewaxing unit may be eliminated by integrating the catalytic dewaxing unit with a catalytic cracking unit. The light cycle oil sidestream from the cat cracker fractionator, bypasses the sidestream stripper and serves as the feed to the catalytic dewaxing unit. The dewaxed product is separated into a gasoline fraction which

Antal

1982-01-01

356

THE DESIGN AND OPERATION OF INDUSTRIAL SCALE PULSE COLUMNS FOR PUREX SERVICE  

Microsoft Academic Search

The development of current recommendations for Purex pulse column ; designs is discussed and reviewed. To obtain a better understanding of the ; radioactive solvent extraction process, a brief description of the Purex Process ; is offered in the form of a flowsheet. The advantages of the pulse column over ; the packed column and the mixersettler are also discussed.

G. L. Richardson; A. M. Platt

1961-01-01

357

Radial heterogeneity of some analytical columns used in high-performance liquid chromatography  

SciTech Connect

An on-column electrochemical microdetector was used to determine accurately the radial distribution of the mobile phase velocity and of the column efficiency at the exit of three common analytical columns, namely a 100 mm x 4.6 mm C18 bonded silica-based monolithic column, a 150 mm x 4.6 mm column packed with 2.7 {micro}m porous shell particles of C18 bonded silica (HALO), and a 150 mm x 4.6 mm column packed with 3 {micro}m fully porous C18 bonded silica particles (LUNA). The results obtained demonstrate that all three columns are not radially homogeneous. In all three cases, the efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius). The decrease in local efficiency from the core to the wall regions was lower in the case of the monolith (ca. 25%) than in that of the two particle-packed columns (ca. 35-50%). The mobile phase velocity was found to be ca. 1.5% higher in the wall than in the core region of the monolithic column while, in contrast, it was ca. 2.5-4.0% lower in the wall region for the two particle-packed columns.

Mriziq, Khaled S [ORNL; Guiochon, Georges A [ORNL

2009-01-01

358

Determination of benzene and toluene in soils and plant material by azeotropic distillation  

SciTech Connect

The suspected dumping of gasoline near a garden resulted in the need for a method that would measure trace amounts of benzene and toluene in both soil and plant samples. In this report the authors show that a method involving methanolic extraction and azeotropic distillation is a highly sensitive technique that eliminated the contamination of the GC column by non-volatile material.

Kozloski, R.P.

1985-01-01

359

Prediction of Temperature and Concentration Distributions of Distillation Sieve Trays by CFD  

Microsoft Academic Search

A three-dimensional two-fluid computational fluid dynamics (CFD) model is developed to predict concentration and temperature distributions on sieve trays of distillation columns and good simulation results are obtained. The dispersed gas phase and continuous liquid phase are modeled in the Eulerian framework as two interpenetrating phases with interphase momentum, heat and mass transfer. Closure models are developed for interphase transfer

Mahmood-Reza Rahimi; Rahbar Rahimi; Farhad Shahraki; Morteza Zivdar

2006-01-01

360

How to design baffle tray columns  

SciTech Connect

As with packed columns, well-known heat transfer equations can be used to estimate mass transfer efficiencies for baffle tray columns. Other variables that can be calculated using this method include: flooding capacity, pressure drop, number of transfer units (NTUs) and the height equivalent to a theoretical plate (HETP). Gas-liquid contacting columns containing simple baffles have been used in hydrocarbon processing industry plants for many years. Principal areas of application have been for contacting liquids containing suspended solids and for quenching hot gases with coolant liquids. They are advantageous for fouling services. But because of their simplistic design they have not been thought to produce high efficiencies for transferring mass or heat. When used primarily for mass transfer purposes, only a few theoretical stages have been expected of them. This paper discusses hydrodynamics, previous studies on the design of baffle tray columns, capacity, pressure drop, and mass transfer efficiency, and gives an example calculation of mass transfer efficiency.

Fair, J.R. (Univ. of Texas, Austin (United States))

1993-05-01

361

The effect of pillar array in semi-packed micro gas chromatography  

Microsoft Academic Search

Micro pillars within separation columns (SC) offer higher sample capacity but also promote fluidic eddy motion which unlike other applications has a negative effect on gas chromatography (GC). Three different semi-packed column (SPC) configurations have been evaluated with respect to pillar spacing along the flow direction and number of pillars across channel. The efficiencies of SPCs have been compared to

Bassam Alfeeli; Shree Narayanan; Mathew McMillan; Daniel Hirtenstein; Gary Rice; Masoud Agah

2011-01-01

362

Random Very Loose Packings  

NASA Astrophysics Data System (ADS)

We measure the number ?(?) of mechanically stable states of volume fraction ? of a granular assembly under gravity. The granular entropy S(?)=log??(?) vanishes both at high density, at ???rcp, and a low density, at ???rvlp, where ?rvlp is a new lower bound we call random very loose pack. ?rlp is the volume fraction where the entropy is maximal. These findings allow for a clear explanation of compaction experiments and provide the first first-principle definition of the random loose volume fraction. In the context of the statistical mechanics approach to static granular materials, states with ?

Ciamarra, Massimo Pica; Coniglio, Antonio

2008-09-01

363

Fractionation and characterization of sulfur compounds in petroleum distillates  

SciTech Connect

In this paper a procedure for the fractionation and the characterization of sulfur containing compounds in petroleum distillated is described. The method is based on a chromatographic separation using alumna columns coated with silver nitrate (Ligard Exchange Chromatography) which permits the separation of molecules containing aromatic sulfur (thiophenic compounds) from the sulfides. The subsequent gc analysis using selective atomic emission detector allows the quantification of the two types of compound s in each fraction. The results of the application of this procedure on an Egyptian gas-oil from Belaym crude are reported.

Del Bianco, A.; Anelli, M. (Eniricerche S.p.A., Via Maritano 26, 20097 S. Donato, Milano (IT)); Riva, A. (Agip S.p.A., Via Maritano 26, 20097 Milano (IT))

1992-01-01

364

Cascade Distillation Subsystem Development: Progress Toward a Distillation Comparison Test  

NASA Technical Reports Server (NTRS)

Recovery of potable water from wastewater is essential for the success of long-duration manned missions to the Moon and Mars. Honeywell International and a team from NASA Johnson Space Center (JSC) are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The wastewater processor, referred to as the Cascade Distillation Subsystem (CDS), utilizes an innovative and efficient multistage thermodynamic process to produce purified water. The rotary centrifugal design of the system also provides gas/liquid phase separation and liquid transport under microgravity conditions. A five-stage subsystem unit has been designed, built, delivered and integrated into the NASA JSC Advanced Water Recovery Systems Development Facility for performance testing. A major test objective of the project is to demonstrate the advancement of the CDS technology from the breadboard level to a subsystem level unit. An initial round of CDS performance testing was completed in fiscal year (FY) 2008. Based on FY08 testing, the system is now in development to support an Exploration Life Support (ELS) Project distillation comparison test expected to begin in early 2009. As part of the project objectives planned for FY09, the system will be reconfigured to support the ELS comparison test. The CDS will then be challenged with a series of human-gene-rated waste streams representative of those anticipated for a lunar outpost. This paper provides a description of the CDS technology, a status of the current project activities, and data on the system s performance to date.

Callahan, M. R.; Lubman, A.; Pickering, Karen D.

2009-01-01

365

Enabling Microliquid Chromatography by Microbead Packing of Microchannels  

NASA Technical Reports Server (NTRS)

The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid enantiomers.

Balvin, Manuel; Zheng, Yun

2014-01-01

366

Enabling Microliquid Chromatography by Microbead Packing of Microchannels  

NASA Technical Reports Server (NTRS)

The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid enantiomers.

Balvin, Manuel; Zheng, Yun

2013-01-01

367

Key distillation in quantum cryptography  

NASA Astrophysics Data System (ADS)

Quantum cryptography is a technique which permits two parties to communicate over an open channel and establish a shared sequence of bits known only to themselves. This task, provably impossible in classical cryptography, is accomplished by encoding the data on quantum particles and harnessing their unique properties. It is believed that no eavesdropping attack consistent with the laws of quantum theory can compromise the secret data unknowingly to the legitimate users of the channel. Any attempt by a hostile actor to monitor the data carrying particles while in transit reveals itself through transmission errors it must inevitably introduce. Unfortunately, in practice a communication is not free of errors even when no eavesdropping is present. Key distillation is a technique that permits the parties to overcome this difficulty and establish a secret key despite channel defects, under the assumption that every particle is handled independently from other particles by the enemy. In the present work, key distillation is described and its various aspects are studied. A relationship is derived between the average error rate resulting from an eavesdropping attack and the amount of information obtained by the attacker. Formal definition is developed of the security of the final key. The net throughput of secret bits in a quantum cryptosystem employing key distillation is assessed. An overview of quantum cryptographic protocols and related information theoretical results is also given.

Slutsky, Boris Aron

1998-11-01

368

Feasible separation modes for various reactive distillation systems  

SciTech Connect

The feasibility of steady states of continuous reactive distillation processes is discussed by applying the theory of static analysis (SA). The generality of this approach is proved by applying several industrial examples, all of which have different reaction schemes and thermodynamical properties. For each example process, the entire feed composition region is divided into several subregions, each of which has similar characteristics for the product composition and the column structure. The information derived by this analysis can be used effectively for the selection of the desirable feed composition and column configurations. The results of various examples indicate that the SA is a very convenient tool that provides an answer to the question of feasibility and provides hints for an early stage of design.

Giessler, S.; Danilov, R.Y.; Pisarenko, R.Y.; Serafimov, L.A.; Hasebe, S.; Hashimoto, I.

1999-10-01

369

Method for dense packing discovery  

NASA Astrophysics Data System (ADS)

The problem of packing a system of particles as densely as possible is foundational in the field of discrete geometry and is a powerful model in the material and biological sciences. As packing problems retreat from the reach of solution by analytic constructions, the importance of an efficient numerical method for conducting de novo (from-scratch) searches for dense packings becomes crucial. In this paper, we use the divide and concur framework to develop a general search method for the solution of periodic constraint problems, and we apply it to the discovery of dense periodic packings. An important feature of the method is the integration of the unit-cell parameters with the other packing variables in the definition of the configuration space. The method we present led to previously reported improvements in the densest-known tetrahedron packing. Here, we use the method to reproduce the densest-known lattice sphere packings and the best-known lattice kissing arrangements in up to 14 and 11 dimensions, respectively, providing numerical evidence for their optimality. For nonspherical particles, we report a dense packing of regular four-dimensional simplices with density ?=128/219?0.5845 and with a similar structure to the densest-known tetrahedron packing.

Kallus, Yoav; Elser, Veit; Gravel, Simon

2010-11-01

370

Irresolvable complex mixture of hydrocarbons in soybean oil deodorizer distillate.  

PubMed

Aliphatic hydrocarbons (HCs) can be used as a fingerprint of a given seed oil. Only by characterization of aliphatic HCs could contamination by mineral oil in that seed oil be confirmed. During the isolation of squalene from soybean oil deodorizer distillate, a significant amount of unknown HCs, ca. 44 wt%, was obtained. These seemingly-easy-to-identify HCs turned out to be much more difficult to elucidate due to the presence of an irresolvable complex mixture (ICM). The objective of this study was to purify and identify the unknown ICM of aliphatic HCs from soybean oil deodorizer distillate. Purification of the ICM was successfully achieved by using modified Soxhlet extraction, followed by modified preparative column chromatography, and finally by classical preparative column chromatography. FT-IR, TLC, elemental analysis, GC/FID, NMR and GC-MS analyses were then performed on the purified HCs. The GC chromatogram detected the presence of ICM peaks comprising two major peaks and a number of minor peaks. Validation methods such as IR and NMR justified that the unknowns are saturated HCs. This work succeeded in tentatively identifying the two major peaks in the ICM as cycloalkane derivatives. PMID:22162261

Ju, Yi-Hsu; Huynh, Lien-Huong; Gunawan, Setiyo; Chern, Yaw-Terng; Kasim, Novy S

2011-12-01

371

UTILIZATION OF ACTIVATED ZEOLITE AS MOLECULAR SIEVE IN CHROMATOGRAPHIC COLUMN FOR SEPARATION OF COAL TAR COMPOUNDS Pemanfaatan Zeolit Aktif sebagai Molecular Sieve untuk Pengisi Kolom Kromatografi pada Pemisahan Komponen Tar Batu Bara  

Microsoft Academic Search

Application of activated zeolite (ZAA) as molecular sieve to separate compounds of coal tar from vaccum fractional distillation, have been done. The size of zeolite was 10-20 mesh and used as solid phase in column chromatography with length of 30 cm. The first step of the research was coal pyrolisis and the product (tar) was distillated by fractional column and

Dwi Retno; Nurotul Wahidiyah; Bambang Setiaji; Iqmal Tahir

372

Packing Products: Polystyrene vs. Cornstarch  

ERIC Educational Resources Information Center

Packing materials such as polystyrene take thousands of years to decompose, whereas packing peanuts made from cornstarch, which some companies are now using, can serve the same purpose, but dissolve in water. The author illustrates this point to her class one rainy day using the sculptures students made from polystyrene and with the cornstarch…

Starr, Suzanne

2009-01-01

373

Packed Planetary Systems  

NASA Astrophysics Data System (ADS)

Planetary systems display a wide range of appearances, with apparently arbitrary values of semi-major axis, eccentricity, etc. We reduce the complexity of orbital configurations to a single value, ? , which is a measure of how close, over secular timescales ( ˜10,000 orbits), two consecutive planets come to each other. We measure this distance relative to the sum of the radii of their Hill spheres, sometimes referred to as mutual Hill radii (MHR). We determine the closest approach distance by numerically integrating the entire system on coplanar orbits, using minimum masses. For non-resonant systems, close approach occurs during apsidal alignment, either parallel or anti-parallel. For resonant pairs the distance at conjunction determines the closest approach distance. Previous analytic work found that planets on circular orbits were assuredly unstable if they came within 3.5 MHR (i.e. Gladman 1993; Chambers, Wetherill & Boss 1996). We find that most known pairs of jovian planets (including those in our solar system) come within 3.5 -- 7 MHR of each other. We also find that several systems are unstable (their closest approach distance is less than 3.5 MHR). These systems, if they are real, probably exist in an observationally permitted location somewhat different from the current best fit. In these cases, the planets' closest approach distance will most likely also be slightly larger than 3.5 MHR. Most pairs beyond 7 MHR probably experienced post-formation migration (i.e. tidal circularization, inward scattering of small bodies) which moved them further apart. This result is even more remarkable since we have used the minimum masses; most likely the systems are inclined to the line of sight, making the Hill spheres larger, and shrinking ? . This dense packing may reflect a tendency for planets to form as close together as they can without being dynamically unstable. This result further implies there may be a large number of smaller, currently undetectable companions packed in orbits around stars with known planets.

Barnes, R.; Greenberg, R.

2005-08-01

374

Vapor Compression Distillation Flight Experiment  

NASA Technical Reports Server (NTRS)

One of the major requirements associated with operating the International Space Station is the transportation -- space shuttle and Russian Progress spacecraft launches - necessary to re-supply station crews with food and water. The Vapor Compression Distillation (VCD) Flight Experiment, managed by NASA's Marshall Space Flight Center in Huntsville, Ala., is a full-scale demonstration of technology being developed to recycle crewmember urine and wastewater aboard the International Space Station and thereby reduce the amount of water that must be re-supplied. Based on results of the VCD Flight Experiment, an operational urine processor will be installed in Node 3 of the space station in 2005.

Hutchens, Cindy F.

2002-01-01

375

Cadmium removal in a biosorption column  

SciTech Connect

New biosorbent material derived from a ubiquitous brown marine alga Ascophyllum nodosum has been examined in packed-bed flow-through sorption columns. It effectively removed 10 mg/L of cadmium down to 1.5 ppb levels in the effluent, representing 99.985% removal. The experimental methodology used was based on the early Bohart and Adams sorption model, resulting in quantitative determination of the characteristic process parameters which can be used for performance comparison and process design. An average metal loading of the biosorbent (N[sub 0]) determined was 30 mg Cd/g, corresponding closely to that observed for the batch equilibrium metal concentration of 10 mg Cd/L. The critical bed depth (D[sub min]) for the potable water effluent quality standard varied with the column feed flow rate from 20 to 50 cm. The sorption column mass transfer and dispersion coefficients were determined, which are also required for solving the sorption model equations.

Volesky, B.; Prasetyo, I. (McGill Univ., Montreal, Quebec (Canada). Dept. of Chemical Engineering)

1994-05-01

376

Application of CFD in the study of supercritical fluid extraction with structured packing: Dry pressure drop calculations  

Microsoft Academic Search

Liquid phase SFE has been carried out in extraction columns, with structured packings particularly of the gauze type. Structured packing performs very well during extractions under these conditions, mainly due to their relatively large surface area and free volume. Nevertheless, there are also important disadvantages such as high cost, low capacities at high flow rates, and premature flooding. The assessment

João Fernandes; Pedro C. Simões; José P. B. Mota; Esteban Saatdjian

2008-01-01

377

C-Store: A Column-oriented DBMS  

Microsoft Academic Search

This paper presents the design of a read-optimized relational DBMS that contrasts sharply with most current systems, which are write-optimized. Among the many differences in its design are: storage of data by column rather than by row, careful coding and packing of objects into storage including main memory during query processing, storing an overlapping collection of column-oriented projections, rather than

Michael Stonebraker; Daniel J. Abadi; Adam Batkin; Xuedong Chen; Mitch Cherniack; Miguel Ferreira; Edmond Lau; Amerson Lin; Samuel Madden; Elizabeth J. O'Neil; Patrick E. O'Neil; Alex Rasin; Nga Tran

2005-01-01

378

Fiber Separation from Distillers Dried Grains with Solubles Using a Larger Elutriation Apparatus and Use of Fiber as a Feedstock for Corn Fiber Gum Production  

Microsoft Academic Search

In an earlier study, a combination of sieving and elutriation (airflow) was found to be effective in separating fiber from distillers dried grains with solubles (DDGS); the elutriation column diameter used was 63 mm. Larger quantities of fractions were needed for conducting studies on coproduct production from the fractions. In this study, an elutriation apparatus with a larger elutriation column

R. Srinivasan; M. P. Yadav; R. L. Belyea; K. D. Rausch; L. E. Pruiett; D. B. Johnston; M. E. Tumbleson; V. Singh

379

A new procedure for the determination of distillation temperature distribution of high-boiling petroleum products and fractions.  

PubMed

The distribution of distillation temperatures of liquid and semi-fluid products, including petroleum fractions and products, is an important process and practical parameter. It provides information on properties of crude oil and content of particular fractions, classified on the basis of their boiling points, as well as the optimum conditions of atmospheric or vacuum distillation. At present, the distribution of distillation temperatures is often investigated by simulated distillation (SIMDIS) using capillary gas chromatography (CGC) with a short capillary column with polydimethylsiloxane as the stationary phase. This paper presents the results of investigations on the possibility of replacing currently used CGC columns for SIMDIS with a deactivated fused silica capillary tube without any stationary phase. The SIMDIS technique making use of such an empty fused silica column allows a considerable lowering of elution temperature of the analytes, which results in a decrease of the final oven temperature while ensuring a complete separation of the mixture. This eliminates the possibility of decomposition of less thermally stable mixture components and bleeding of the stationary phase which would result in an increase of the detector signal. It also improves the stability of the baseline, which is especially important in the determination of the end point of elution, which is the basis for finding the final temperature of distillation. This is the key parameter for the safety process of hydrocracking, where an excessively high final temperature of distillation of a batch can result in serious damage to an expensive catalyst bed. This paper compares the distribution of distillation temperatures of the fraction from vacuum distillation of petroleum obtained using SIMDIS with that obtained by the proposed procedure. A good agreement between the two procedures was observed. In addition, typical values of elution temperatures of n-paraffin standards obtained by the two procedures were compared. Finally, the agreement between boiling points of polar compounds determined from their retention times and actual boiling points was investigated. PMID:21153592

Boczkaj, Grzegorz; Przyjazny, Andrzej; Kami?ski, Marian

2011-03-01

380

Nasal packing after septoplasty: a randomized comparison of packing versus no packing in 88 patients.  

PubMed

The once-common practice of packing the nose after septoplasty was based on a desire to prevent postoperative complications such as bleeding, septal hematoma, and adhesion formation. However, it was since found that not only is nasal packing ineffective in this regard, it can actually cause these complications. Although the consensus in the world literature is that packing should be avoided, to the best of our knowledge, no truly randomized study has been undertaken in Southwest Asia upon which to justify this recommendation here. Therefore, we conducted a prospective randomized comparison of the incidence of a variety of postoperative signs and symptoms in 88 patients, 15 years of age and older, who did (n = 44) and did not (n = 44) undergo nasal packing following septoplasty. We found that the patients who underwent packing experienced significantly more postoperative pain, headache, epiphora, dysphagia, and sleep disturbance on the night of surgery. Oral and nasal examinations 7 days postoperatively revealed no significant difference between the two groups in the incidence of bleeding, septal hematoma, adhesion formation, and local infection. Finally, the packing group reported a moderate to high level of pain during removal of the packing. Our findings confirm that nasal packing after septoplasty is not only unnecessary, it is actually a source of patient discomfort and other signs and symptoms. PMID:19006062

Awan, Mohammad Sohail; Iqbal, Moghira

2008-11-01

381

Distillation of liquid fuels by thermogravimetry  

SciTech Connect

In this paper, design and operation of a custom-built thermogravimetric apparatus for the distillation of liquid fuels are reported. Using a sensitive balance with scale of 0.001 g and ASTM distillation glassware, several petroleum and petroleum-derived samples have been analyzed by the thermogravimetric distillation method. When the ASTM distillation glassware is replaced by a micro-scale unit, sample size could be reduced from 100 g to 5-10 g. A computer program has been developed to transfer the data into a distillation plot, e.g. Weight Percent Distilled vs. Boiling Point. It also generates a report on the characteristic distillation parameters, such as, IBP (Initial Boiling Point), FBP (Final Boiling Point), and boiling point at 50 wt% distilled. Comparison of the boiling point distributions determined by TG (thermogravimetry) with those by SimDis GC (Simulated-Distillation Gas Chromatography) on two liquid fuel samples (i.e. a decanted oil and a filtered crude oil) are also discussed in this paper.

Huang, He; Wang, Keyu; Wang, Shaojie; Klein, M.T.; Calkins, W.H.

1996-12-31

382

System maps for retention of neutral organic compounds under isocratic conditions on a reversed-phase monolithic column.  

PubMed

The solvation parameter model is used to create systems maps for the separation of neutral organic compounds on a Chromolith Performance RP-18e octadecylsiloxane-bonded silica-based monolithic column for water-acetonitrile and water-methanol mobile phase compositions from 10 to 70% (v/v) organic solvent. These results demonstrate that the retention properties of the monolithic column are similar to those of conventional octadecylsiloxane-bonded silica particle-packed columns. It is further shown that the selectivity for the monolithic column falls within the selectivity range for typical particle-packed columns at two mobile phase compositions for which a direct comparison is possible. PMID:12899300

Chu, Yun; Poole, Colin F

2003-06-27

383

Valve stem and packing assembly  

DOEpatents

A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

Wordin, J.J.

1991-09-03

384

Valve stem and packing assembly  

DOEpatents

A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

Wordin, John J. (Bingham County, ID)

1991-01-01

385

Dense periodic packings of tori  

NASA Astrophysics Data System (ADS)

Dense packings of nonoverlapping bodies in three-dimensional Euclidean space R3 are useful models of the structure of a variety of many-particle systems that arise in the physical and biological sciences. Here we investigate the packing behavior of congruent ring tori in R3, which are multiply connected nonconvex bodies of genus 1, as well as horn and spindle tori. Specifically, we analytically construct a family of dense periodic packings of unlinked tori guided by the organizing principles originally devised for simply connected solid bodies [22 Torquato and Jiao, Phys. Rev. E 86, 011102 (2012), 10.1103/PhysRevE.86.011102]. We find that the horn tori as well as certain spindle and ring tori can achieve a packing density not only higher than that of spheres (i.e., ? /?18 =0.7404...) but also higher than the densest known ellipsoid packings (i.e., 0.7707...). In addition, we study dense packings of clusters of pair-linked ring tori (i.e., Hopf links), which can possess much higher densities than corresponding packings consisting of unlinked tori.

Gabbrielli, Ruggero; Jiao, Yang; Torquato, Salvatore

2014-02-01

386

Single Column Pyrotechnic Delay.  

National Technical Information Service (NTIS)

In the past, rocket assisted artillery projectiles used dual column pyrotechnic delays as a mechanism for igniting the rocket motor. The development of a single column pyrotechnic delay is discussed. Design methodology and results of testing are also disc...

W. W. Smith

1996-01-01

387

Endurance Test for SCK-CEN Catalytic Mixed Packing, Proposed for Water Detritiation System at JET  

SciTech Connect

JET machine's operation lead to continuously generation of tritiated water and therefore, it is necessary to consider the development of a Water Detritiation System (WDS) for JET and also for ITER. The key point of WDS is the efficiency and stability of liquid phase catalytic exchange (LPCE) column, that has to achieve a high decontamination of tritiated streams.Two catalytic mixed packing based on hydrophobic Pt-catalyst, and having closed separation performances have been proposed for LPCE column. A complete data base concerning the influence of {beta}-radiation of tritium and the influence of impurities from feed streams on the catalytic mixed packing' s performances and parameters is absolutely necessary.The results of 3 months endurance test for one of these packing (SCK-CEN packing), are presented in this paper. No significant modifications of performances and physico-structural parameters have been observed.

Ionita, Gh. [National Institute for Cryogenics and Isotopic Separation (Romania); Bornea, A. [National Institute for Cryogenics and Isotopic Separation (Romania); Braet, J. [SCK-CEN (Belgium); Popescu, I. [National Institute for Cryogenics and Isotopic Separation (Romania); Stefanescu, I. [National Institute for Cryogenics and Isotopic Separationn (Romania); Bidica, N. [National Institute for Cryogenics and Isotopic Separation (Romania); Varlam, C [National Institute for Cryogenics and Isotopic Separation (Romania); Postolache, Cr. [National Insitute of Physics and Nuclear Engineering (Romania); Mateic, L. [National Insitute of Physics and Nuclear Engineering (Romania)

2005-07-15

388

Hydrotreating of Mixtures of Coal Derived Middle Distillate and Petroleum Middle Distillates.  

National Technical Information Service (NTIS)

The mixtures of 50 vol % Wandoan coal derived middle distillate (C) and 50 vol % petroleum middle distillate (Ta-Ching (T), Iranian heavy (I), Khafji (K) ) or middle distillate from Cold Lake oil sand bitumen (O) were hydrotreated using a Ni-Mo-Al2O3 cata...

T. Kondo K. Ukegawa A. Matsumura K. Koguchi

1984-01-01

389

Performance Analysis of 'Star' Pack Cushion Inserts.  

National Technical Information Service (NTIS)

The objectives of the study were two-fold: (1) Modify 'Star' pack cushion inserts to provide more uniform cushioning protection and most cost effective pack; and (2) determine adequacy of previously published 'Star' pack performance data for representing ...

R. V. Brown

1974-01-01

390

Bioremediation of Perchlorate-Contaminated Groundwater Using a Packed Bed Biological Reactor  

Microsoft Academic Search

The objective of this study was to assess the efficacy of a bench-scale, acetate-fed, packed bed bioreactor (PBR) to treat low concentrations (>1 mg L) of perchlorate (ClO4 ) in groundwater collected from an impacted site. The PBR consisted of a cylindrical plexiglass column packed with Celite, a diatomaceous earth product, as a solid support medium. The reactor was inoculated

M. E. Losi; T. Giblin; V. Hosangadi; W. T. Frankenberger Jr

2002-01-01

391

Influence of type of distillation apparatus on chemical profiles of brazilian cachaças.  

PubMed

Brazilian cachaças (115 samples; 73 samples derived from distillation in copper pot stills, 42 samples derived from distillation in stainless steel columns), collected directly at the producers, were analyzed for the contents of 34 constituents by chromatography, inductively coupled plasma optical emission spectrometry, and atomic absorption spectrometry. The analytical data were subjected to principal component analysis (PCA) and linear discriminant analysis (LDA). The PCA treatment led to discrimination of the two groups of cachaças, explaining 65.0% of the database variance. Using LDA and ethanal, ethyl carbamate, dimethyl sulfide, isobutyl alcohol, n-propanal, copper, ethyl acetate, and phenylmethanal as chemical descriptors, a model was developed that presented 95.1% accuracy in predicting the type of distillation apparatus. PMID:17629298

Reche, Roni Vicente; Neto, Alexandre Ferreira Leite; Silva, Alexandre Ataide Da; Galinaro, Carlos Alexandre; Osti, Renata Zachi De; Franco, Douglas Wagner

2007-08-01

392

High efficiency microbore GC columns using porous bead supports  

Microsoft Academic Search

Summary  Theoretical comparisons of various packed GC column types are presented with respect to analysis time, efficiency, sample dilution, and sample capacity for a given maximum inlet pressure. In particular, totally porous particles, porous layer beads, and glass beads are compared with one another. It is shown that 30 m porous layer beads offer a useful compromise between analysis time and

D. A. Lewis; Paul Vouros; B. L. Karger

1982-01-01

393

Regular Packings on Periodic Lattices  

NASA Astrophysics Data System (ADS)

We investigate the problem of packing identical hard objects on regular lattices in d dimensions. Restricting configuration space to parallel alignment of the objects, we study the densest packing at a given aspect ratio X. For rectangles and ellipses on the square lattice as well as for biaxial ellipsoids on a simple cubic lattice, we calculate the maximum packing fraction ?d(X). It is proved to be continuous with an infinite number of singular points X?min?,X?max?, ?=0,±1,±2,…. In two dimensions, all maxima have the same height, whereas there is a unique global maximum for the case of ellipsoids. The form of ?d(X) is discussed in the context of geometrical frustration effects, transitions in the contact numbers, and number-theoretical properties. Implications and generalizations for more general packing problems are outlined.

Ras, Tadeus; Schilling, Rolf; Weigel, Martin

2011-11-01

394

Regular packings on periodic lattices.  

PubMed

We investigate the problem of packing identical hard objects on regular lattices in d dimensions. Restricting configuration space to parallel alignment of the objects, we study the densest packing at a given aspect ratio X. For rectangles and ellipses on the square lattice as well as for biaxial ellipsoids on a simple cubic lattice, we calculate the maximum packing fraction ?(d)(X). It is proved to be continuous with an infinite number of singular points X(?)(min), X(?)(max), ? = 0, ±1, ±2,…. In two dimensions, all maxima have the same height, whereas there is a unique global maximum for the case of ellipsoids. The form of ?(d)(X) is discussed in the context of geometrical frustration effects, transitions in the contact numbers, and number-theoretical properties. Implications and generalizations for more general packing problems are outlined. PMID:22181895

Ras, Tadeus; Schilling, Rolf; Weigel, Martin

2011-11-18

395

Frac pack technology still evolving  

SciTech Connect

Success of frac packs depends on candidate selection, treatment design, fluids and proppants, downhole tools, and treatment implementation. Current frac packing techniques have partially evolved from high-permeability stimulation in the Kuparuk field, Alaska. In the Gulf of Mexico (GOM), attempts were made as early as the mid-1960s to hydraulically fracture sands. These early treatments were not highly successful because of techniques, understanding of rock mechanical properties, and poor candidate selection. This article focuses primarily on frac packs in GOM wells, although this technique is also used in South America, Southeast Asia, Pakistan, Nigeria, Alaska, and Europe. Through mid-year 1995 in the GOM alone, there have been over 600 frac packs.

Ebinger, C.D. [Ely and Associates Inc., Houston, TX (United States)

1995-10-23

396

Water Purification by Membrane Distillation Process  

Microsoft Academic Search

The demineralization of water by membrane distillation (MD) has been investigated. In the first stage of investigations the tap water or boiled tap water was employed as a feed, and the water recovery coefficient exceeding 75% was achieved. The obtained concentrate was supplied to the second stage of MD installation. The quality of distillate was stable and practically independent of

Marek Gryta

2006-01-01

397

Distillation of liquid fuels by thermogravimetry.  

National Technical Information Service (NTIS)

In this paper, design and operation of a custom-built thermogravimetric apparatus for the distillation of liquid fuels are reported. Using a sensitive balance with scale of 0.001 g and ASTM distillation glassware, several petroleum and petroleum-derived s...

H. Huang K. Wang S. Wang M. T. Klein W. H. Calkins

1996-01-01

398

Membrane distillation. II. Direct contact MD  

Microsoft Academic Search

Pure water direct contact membrane distillation (DCMD) experiments were used to measure the permeability parameter associated with the molecular diffusion in membrane distillation (MD). The fluxes given by a recently reported MD model, which is based on the dusty-gas model of gas transport through porous media, showed good agreement with the experimental results over the entire range of feed temperatures

Kevin W. Lawson; Douglas R. Lloyd

1996-01-01

399

Heat transport in the membrane distillation process  

Microsoft Academic Search

Investigation of membrane distillation (MD) with a laminar flow of the streams in a module has been performed. The equations describing the heat transfer in MD capillary modules were presented and verified experimentally. The equations were derived for the calculation of the feed and distillate temperature at a layer adjacent to the membrane. The heat transfer correlations were implemented in

Marek Gryta; Maria Tomaszewska

1998-01-01

400

Distillation of Bell states in open systems  

SciTech Connect

In this work we show that the distillation protocol proposed by P. Chen et al. [Phys. Rev. A 54, 3824 (1996)] allows one to distill Bell states at any time for a system evolving in vacuum and prepared in an initial singlet. It is also shown that the same protocol, applied in nonzero temperature thermal baths, yields a considerable recovering of entanglement.

Isasi, E.; Mundarain, D. [Departamento de Fisica, Seccion de Fenomenos Opticos, Universidad Simon Bolivar, Apartado Postal 89000, Caracas 1080A (Venezuela, Bolivarian Republic of)

2010-04-15

401

Vacuum distillation of ethanol. Final report  

Microsoft Academic Search

The objective was to determine whether distillation at or below a pressure of 70 mm of Hg would produce ethanol sufficiently anhydrous to permit mixing with gasoline without separation. The reason for this is that below 70 mm of Hg, the azeotrope does not form and, theoretically, 100% ethanol can be achieved by fractional distillation. There was insufficient information available

1982-01-01

402

DIFFUSIONAL DISTILLATION IN A GAS STREAM  

Microsoft Academic Search

A laboratory plant is described where fractional water distillation for ; O¹⁸ concentration is performed by diffusional distillation into a carrier ; inert gas. The operating pressure is not less than atmospheric, while the ; operating temperature (20 to 30 deg C) allows a good separation factor to be ; achieved. The whole plant is an assembly of 100 vertical

M. Silvestri; S. Villani; N. Adorni; G. C. Angelino

1959-01-01

403

Nondistillable Entanglement Guarantees Distillable Entanglement  

NASA Astrophysics Data System (ADS)

The monogamy of entanglement is one of the basic quantum mechanical features, which says that when two partners Alice and Bob are more entangled then either of them has to be less entangled with the third party. Here we qualitatively present the converse monogamy of entanglement: given a tripartite pure system and when Alice and Bob are entangled and nondistillable, then either of them is distillable with the third party. Our result leads to the classification of tripartite pure states based on bipartite reduced density operators, which is a novel and effective way to this long-standing problem compared to the means by stochastic local operations and classical communications. Furthermore we systematically indicate the structure of the classified states and generate them. We also extend our results to multipartite states.

Chen, Lin; Hayashi, Masahito

2013-06-01

404

On packing R-trees  

Microsoft Academic Search

We propose new R-tree packing techniques for static databases. Given a collection of rectangles, we sort them and build the R-tree bottom-up. There are several ways to sort the rectangles; the innovation of this work is the use of fractals, and specifically the hilbert curve, to achieve better ordering of the rectangles and eventually better pack- ing. We proposed and

Ibrahim Kamel; Christos Faloutsos

1993-01-01

405

Are proteins well-packed?  

PubMed Central

The average packing density inside proteins is as high as in crystalline solids. Does this mean proteins are well-packed? We go beyond average densities, and look at the full distribution functions of free volumes inside proteins. Using a new and rigorous Delaunay triangulation method for parsing space into empty and filled regions, we introduce formal definitions of interior and surface packing densities. Although proteins look like organic crystals by the criterion of average density, they look more like liquids and glasses by the criterion of their free volume distributions. The distributions are broad, and the scalings of volume-to-surface, volume-to-cluster-radius, and numbers of void versus volume show that the interiors of proteins are more like randomly packed spheres near their percolation threshold than like jigsaw puzzles. We find that larger proteins are packed more loosely than smaller proteins. And we find that the enthalpies of folding (per amino acid) are independent of the packing density of a protein, indicating that van der Waals interactions are not a dominant component of the folding forces.

Liang, J; Dill, K A

2001-01-01

406

Automated metal-free multiple-column nanoLC for improved phosphopeptide analysis sensitivity and throughput  

SciTech Connect

We report on the development and characterization of an automated metal-free nanoscale multiple-capillary system for reversed-phase liquid chromatography-mass spectrometry analysis of phosphopeptides. The system incorporates a capillary column (50 um i.d. × 30 cm, packed with 5 um C18 particles) coupled on-line to a solid phase extraction column (150 um i.d. × 4 cm, packed with 5 um C18 particles). Electrospray ionization tips are constructed on the packed capillary column to couple the reversed-phase liquid chromatographic separation to a linear ion trap tandem mass spectrometer.

Zhao, Rui; Ding, Shi-Jian; Shen, Yufeng; Camp, David G.; Livesay, Eric A.; Udseth, Harold R.; Smith, Richard D.

2009-03-15

407

Closed-Loop Helical Distillation Apparatus. Progress Report.  

National Technical Information Service (NTIS)

The objectives of the project are to: design and construct a more efficient mash distillation unit; reduce physical size and material cost in distillation; use readily available material in the construction of distillation equipment; and improve the opera...

D. L. Gahimer

1981-01-01

408

27 CFR 19.32 - Experimental distilled spirits plants.  

Code of Federal Regulations, 2013 CFR

...false Experimental distilled spirits plants. 19.32 Section 19.32 Alcohol...TREASURY ALCOHOL DISTILLED SPIRITS PLANTS Administrative and Miscellaneous Provisions...32 Experimental distilled spirits plants. (a) General. The...

2013-04-01

409

Use of a Batch Reactive Distillation with Dynamic Optimization Strategy to Achieve Industrial Grade Ethyl Acetate  

NASA Astrophysics Data System (ADS)

Industrial grade ethyl acetate is available with minimum purity of 85.0%. It is mostly produced by an ethanol esterification in a distillation process on both batch and continuous modes. However, researches on high purity production with short operating time are rarely achieved. Therefore, the objective in this work is to study an approach to produce ethyl acetate of 90.0% by 8 hours using a batch reactive distillation column. Based on open-loop simulations, the distillation with constant reflux ratio cannot achieve the product specification. Thus, the dynamic optimization strategy is proposed to handle this problem. For the process safety--preventing the dried column and fractured, a minimum reflux ratio must be determined in advance and then an optimal reflux profile is calculated to achieve optimal product yield. Simulation results show that the industrial grade ethyl acetate can be produced by the dynamic optimization programming with two or more time intervals. Besides, the increasing of time intervals can produce more distillate product.

Konakom, Kwantip; Saengchan, Aritsara; Kittisupakorn, Paisan; Mujtaba, Iqbal M.

2011-08-01

410

Computer aided design of reactive distillation processes for the treatment of waste waters polluted with acetic acid  

Microsoft Academic Search

A theoretical study of reactive distillation processes to remove acetic acid from its 30wt% aqueous solution by esterification with n-butanol is presented. Two different column structures were identified rendering theoretically close to 100 percent conversion of acetic acid. A model capable of precisely predicting the potential phase split is used. Total costs for the new processes are estimated and compared

Jignesh Gangadwala; G. Radulescu; Achim Kienle; K. Sundmacher

2007-01-01

411

Comparison of advanced distillation control methods. Second annual report  

SciTech Connect

Detailed dynamic simulations of two industrial distillation columns (a propylene/propane splitter and a xylene/toluene column) have been used to study the issue of configuration selection for diagonal PI dual composition controls. Auto Tune Variation (ATV) identification with on-line detuning was used for tuning the diagonal proportional integral (PI) composition controls. Each configuration was evaluated with respect to steady-state relative gain array (RGA) values, sensitivity to feed composition changes, and open loop dynamic performance. Each configuration was tuned using setpoint changes over a wider range of operation for robustness and tested for feed composition upsets. Overall, configuration selection was shown to have a dominant effect upon control performance. Configuration analysis tools (e.g., RGA, condition number, disturbance sensitivity) were found to reject configuration choices that are obviously poor choices, but were unable to critically differentiate between the remaining viable choices. Configuration selection guidelines are given although it is demonstrated that the most reliable configuration selection approach is based upon testing the viable configurations using dynamic column simulators.

Riggs, J.B.

1996-11-01

412

Shell and small particles; evaluation of new column technology.  

PubMed

The performance of 5 cm long columns packed with shell particles was compared to totally porous sub-2 microm particles in gradient and isocratic elution separations of hormones (dienogest, finasteride, gestodene, levonorgestrel, estradiol, ethinylestradiol, noretistherone acetate, bicalutamide and tibolone). Peak capacities around 140-150 could be achieved in 25 min with the 5 cm long columns. The Ascentis Express column (packed with 2.7 microm shell particles) showed similar efficiency to sub-2 microm particles under gradient conditions. Applying isocratic separation, the column of 2.7 microm shell particles had a reduced plate height minimum of approximately h=1.6. It was much smaller than obtained with totally porous particles (h approximately = 2.8). The impedance time also proved more favorable with 2.7 microm shell particles than with totally porous particles. The influence of extra-column volume on column efficiency was investigated. The extra-column dispersion of the chromatographic system may cause a shift of the HETP curves. PMID:19038515

Fekete, Szabolcs; Fekete, Jeno; Ganzler, Katalin

2009-01-15

413

Mass transfer kinetics, band broadening and column efficiency.  

PubMed

Important progress was recently made in our understanding of the physico-chemical aspects of mass transfer kinetics in chromatographic columns, in methods used for accurate determination of the different contributions to the height equivalent to a theoretical plate (HETP), and in the application of these advances to the elucidation of mass transfer mechanisms in columns packed with recent chromatographic supports (sub-2 ?m fully porous particles, sub-3 ?m core-shell particles, and monoliths). The independent contributions to the HETP are longitudinal diffusion, eddy dispersion, liquid-solid mass transfer (including trans-particle or trans-skeleton mass transfer and external film mass transfer), and the contributions caused by the thermal heterogeneity of the column. The origin and importance of these contributions are investigated in depth. This work underlines the areas in which improvements are needed, an understanding of the contribution of the external film mass transfer term, a better design of HPLC instruments providing a decrease of the extra-column band broadening contributions to the apparent HETP, the development of better packing procedures giving more radially homogeneous column beds, and new packing materials having a higher thermal conductivity to eliminate the nefarious impact of heat effects in very high pressure liquid chromatography (vHPLC) and supercritical fluid chromatography (SFC). PMID:21664619

Gritti, Fabrice; Guiochon, Georges

2012-01-20

414

Treatment of Aroclor 1016 contaminated soil by hydrogen peroxide: laboratory column study  

Microsoft Academic Search

The potential and feasibility of treating soil contaminated with electrical insulating oil, Aroclor 1016, containing polychlorinated biphenyls (PCBs) with stabilized hydrogen peroxide were evaluated using columns packed with soils of two different matrixes. The column experiments showed that PCBs degraded by the stabilized hydrogen peroxide treatment in both soil matrixes, although the efficacy of the treatment depended strongly on the

Marika Viisimaa; Jelena Veressinina; Anna Goi

2012-01-01

415

TRANSPORT OF MACROMOLECULES AND HUMATE COLLOIDS THROUGH A SAND AND A CLAY AMENDED SAND LABORATORY COLUMN  

EPA Science Inventory

Laboratory experiments were conducted to determine if macromolecules or humate colloids would transport through sand columns and if they would exhibit any variations in their relative velocity based upon their molecular volumes and the pore size distribution of the column packing...

416

DESIGN SCALE-UP SUITABILITY FOR AIR-STRIPPING COLUMNS (JOURNAL VERSION)  

EPA Science Inventory

An investigation was conducted to determine the suitability of a design scale-up from pilot-scale to full-scale air-stripping columns used in the removal of volatile organic compounds from contaminated water supplies. Forty-eight experimental runs were made in packed columns of f...

417

EFFECT OF NITRATE-BASED BIOREMEDIATION ON CONTAMINANT DISTRIBUTION AND SEDIMENT TOXICITY-COLUMN STUDY  

EPA Science Inventory

A laboratory column study was set up to evaluate changes in contaminant distribution and sediment toxicity following nitrate-based bioremediation and to correlate toxicity reduction with loss of fuel components. Glass columns were packed with sediment from an aquifer that had be...

418

Separation of butanol from acetone-butanol-ethanol fermentation by a hybrid extraction-distillation process  

Microsoft Academic Search

The alternative fuel butanol can be produced via acetone–butanol–ethanol (ABE) fermentation from biomass. The high costs for the separation of ABE from the dilute fermentation broth have so far prohibited the industrial-scale production of bio-butanol. In order to facilitate an effective and energy-efficient product removal, we suggest a hybrid extraction–distillation downstream process with ABE extraction in an external column. By

Korbinian Kraemer; Andreas Harwardt; Rob Bronneberg; Wolfgang Marquardt

2011-01-01

419

Conceptual design of a reactive distillation process for ultra-low sulfur diesel production  

Microsoft Academic Search

Based on a thermodynamic analysis in terms of reaction-separation feasibility, a conceptual design of a reactive distillation column for ultra-low sulfur diesel production has been developed. The thermodynamic analysis considers the computation of reactive and non-reactive residue curve maps for a mixture that models the sulfured diesel fuel. The visualization of the reactive residue curves is posed in terms of

Tomás Viveros-García; J. Alberto Ochoa-Tapia; Ricardo Lobo-Oehmichen; J. Antonio de los Reyes-Heredia; Eduardo S. Pérez-Cisneros

2005-01-01

420

Analytical Investigation of the Sesquiterpene Hydrocarbons of Distilled Lime Oil (Citrus aurantifolia Swingle)  

Microsoft Academic Search

The composition of sesquiterpene hydrocarbons of distilled lime oils of different geographic origin was analyzed in detail. Gas chromatography on capillary columns of varied polarity was employed for the optimal separation of the components in GC\\/MS. This led to the unambiguous identification of a number of sesquiterpenes. ?-Santalene, ?-amorphene, epi-?-santalene, ?-sesquiphellandrene, 4(14),7(11)-selinadiene and (E)-?-bisabolene were confirmed as so far unknown

Wolfgang Feger; Herbert Brandauer; Manfred Ziegler

1999-01-01

421

Cascade Distiller System Performance Testing Interim Results  

NASA Technical Reports Server (NTRS)

The Cascade Distillation System (CDS) is a rotary distillation system with potential for greater reliability and lower energy costs than existing distillation systems. Based upon the results of the 2009 distillation comparison test (DCT) and recommendations of the expert panel, the Advanced Exploration Systems (AES) Water Recovery Project (WRP) project advanced the technology by increasing reliability of the system through redesign of bearing assemblies and improved rotor dynamics. In addition, the project improved the CDS power efficiency by optimizing the thermoelectric heat pump (TeHP) and heat exchanger design. Testing at the NASA-JSC Advanced Exploration System Water Laboratory (AES Water Lab) using a prototype Cascade Distillation Subsystem (CDS) wastewater processor (Honeywell d International, Torrance, Calif.) with test support equipment and control system developed by Johnson Space Center was performed to evaluate performance of the system with the upgrades as compared to previous system performance. The system was challenged with Solution 1 from the NASA Exploration Life Support (ELS) distillation comparison testing performed in 2009. Solution 1 consisted of a mixed stream containing human-generated urine and humidity condensate. A secondary objective of this testing is to evaluate the performance of the CDS as compared to the state of the art Distillation Assembly (DA) used in the ISS Urine Processor Assembly (UPA). This was done by challenging the system with ISS analog waste streams. This paper details the results of the AES WRP CDS performance testing.

Callahan, Michael R.; Pensinger, Stuart; Sargusingh, Miriam J.

2014-01-01

422

Disc pack cleaning table saves computer time  

NASA Technical Reports Server (NTRS)

Disc pack holding table is support frame upon which computer disc pack is loaded and protective cover released. This combination permits manual off-line cleaning of disc pack storage units at any time without shutting down the computer, and eliminates on-line disc drive unit to hold pack during cleaning.

Guy, J. T., Sr.

1970-01-01

423

Five Points on Columns  

PubMed Central

“Column,” like “gene,” has both conceptual and linguistic shortcomings. The simple question “what is a column” is not easy to answer and the word itself is not easy to replace. In the present article, I have selected five points, in no way comprehensive or canonical, but which may nevertheless serve as a prompt and aid for further discussions and re-evaluation. These are: that anatomical columns are not solid structures, that they are part of locally interdigitating systems, that any delimited column also participates in a widely distributed network, that columns are not an obligatory cortical feature, and that columns (as “modules”) occur widely in the brain in non-cortical structures. I focus on the larger scale macrocolumns, mainly from an anatomical perspective. My position is that cortical organization is inherently dynamic and likely to incorporate multiple processing styles. One can speculate that the distributed mappings within areas like piriform cortex may resemble at least one mode of neocortical processing strategy.

Rockland, Kathleen S.

2010-01-01

424

Sleeping distance in wild wolf packs  

USGS Publications Warehouse

Sleeping distances were observed among members of 13 wild wolf (Canis lupus) packs and 11 pairs in northeastern Minnesota to determine if the distances correlated with pack size and composition. The study utilized aerial radio-tracking and observation during winter. Pack size and number of adults per pack were inversely related to pack average sleeping distance and variability. No correlation between sleeping distance and microclimate was observed. Possible relationships between social bonding and our results are discussed.

Knick, S.T.; Mech, L.D.

1980-01-01

425

[Electroflotation packing of mycelial wastes].  

PubMed

Data on testing a pilot plant for electroflotative packing of mycelial wastes are presented. Both the mycelial wastes and their mixtures were used. Concentration of dry substances raged from 3.5 to 131 g/l. The process was performed with varying flow density and consumption rate of the liquid supplied to the plant. Insoluble magnetite and ruthenium oxide anodes were used. The moister content in the packed phase was 81-97.5 per cent. The study provided specification of the process technological parameters and investigation of the flotator hydroulic characteristics. PMID:2751387

Nikolaev, V B; Karpukhin, V F; Zav'ialova, E V; Faingol'd, Z L

1989-04-01

426

Capillary electrochromatography using continuous-bed columns of sol–gel bonded silica particles with mixed-mode octadecyl and propylsulfonic acid functional groups  

Microsoft Academic Search

Continuous-bed columns containing sol–gel bonded 3 ?m silica particles with mixed-mode octadecyl and propylsulfonic acid functional groups (ODS\\/SCX) were prepared by first packing the ODS\\/SCX particles into a fused-silica capillary, then filling the packed capillary with a siliceous sol–gel, curing the sol–gel, and finally drying the column with supercritical carbon dioxide. The performance of the sol–gel bonded ODS\\/SCX columns was

Qinglin Tang; Milton L Lee

2000-01-01

427

Economic Distribution of Distilled Spirits Within DOD.  

National Technical Information Service (NTIS)

The primary objective was to determine whether the military exchange systems provided the most economical method of distributing distilled spirits. The audit also evaluated whether using commercial distributors rather than military exchange distribution c...

S. R. Young R. D. Kidd M. A. Joseph T. J. Tonkovis S. M. Hutcherson

1998-01-01

428

Minimizing corrosion in coal liquid distillation  

DOEpatents

In an atmospheric distillation tower of a coal liquefaction process, tower materials corrosion is reduced or eliminated by introduction of boiling point differentiated streams to boiling point differentiated tower regions.

Baumert, Kenneth L. (Emmaus, PA); Sagues, Alberto A. (Lexington, KY); Davis, Burtron H. (Georgetown, KY)

1985-01-01

429

Multipartite secret key distillation and bound entanglement  

SciTech Connect

Recently it has been shown that quantum cryptography beyond pure entanglement distillation is possible and a paradigm for the associated protocols has been established. Here we systematically generalize the whole paradigm to the multipartite scenario. We provide constructions of new classes of multipartite bound entangled states, i.e., those with underlying twisted Greenberger-Horne-Zeilinger (GHZ) structure and nonzero distillable cryptographic key. We quantitatively estimate the key from below with the help of the privacy squeezing technique.

Augusiak, Remigiusz; Horodecki, Pawel [Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-952 Gdansk (Poland) and ICFO-Institute Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-952 Gdansk (Poland)

2009-10-15

430

Inflatable Column Structure  

NASA Technical Reports Server (NTRS)

Lightweight structural member easy to store. Billowing between circumferential loops of fiber inflated column becomes series of cells. Each fiber subjected to same tension along entire length (though tension is different in different fibers). Member is called "isotensoid" column. Serves as jack for automobiles or structures during repairs. Also used as support for temporary bleachers or swimming pools.

Hedgepeth, J. M.

1985-01-01

431

The book review column  

Microsoft Academic Search

Welcome to the Book Reviews Column. We hope to bring you at least two reviews of books every month. In this column four books are reviewed. 1. Stable Marriage and its Relation to Other Combinatorial Problems: An Intro- duction to Algorithm Analysis by Donald Knuth. Reviewed by Tim McNichol. This book uses the stable marriage problem as motivation to look

William I. Gasarch

2004-01-01

432

Support Column of Bridge  

USGS Multimedia Gallery

Support column of bridge across Struve Slough, Highway 1. Enlargement of hole where support enters the ground is an effect of lateral shaking, which caused the concrete to break up where the column joined the bridge and was instrumental in the roadbed collapse....

2009-01-26

433

Fixed Packed Bed Reactors in Reduced Gravity  

NASA Technical Reports Server (NTRS)

We present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients k(L)a and k(G)a (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

2004-01-01

434

Fixed Packed Bed Reactors in Reduced Gravity  

NASA Technical Reports Server (NTRS)

We present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid and liquid-solid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients kLa and kGa (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

2004-01-01

435

Lab on a chip packing of submicron particles for high performance EOF pumping.  

PubMed

The packing of submicrometer sized silica beads inside a microchannel was enabled by a novel method which avoids the complication and limitations of generating a frit using conventional approaches and the restriction of flow using a submicrometer sized weir. A micrometer sized weir and two short columns of 5 ?m and 800 nm silica beads packed in succession behind the weir together functioned as a high pressure frit to allow the construction of a primary packed bed of 390 nm silica beads. This packed bed microchannel was tested as an EOF pump, wherein it exhibited superior performance with regards to pressure tolerance, i.e., sustaining good flow rate under extremely high back pressure, and maximal pressure generation. Under a modest applied electric field strength of 150 V/cm, the flow rate against a back pressure of 1200 psi (?8.3 MPa) was 40 nL/min, and the maximal pressure reached 1470 psi (?10 MPa). This work has demonstrated that it is possible to create a high performance packed bed microchannel EOF pump using nanometer sized silica beads, as long as proper care is taken during the packing process to minimize the undesirable mixing of two different sized particles at the boundaries between particle segments and to maximize the packing density throughout the entire packed bed. PMID:20926092

Lu, Qin; Collins, Greg E

2010-11-01

436

Quantum Nonlocal Boxes Exhibit Stronger Distillability  

NASA Astrophysics Data System (ADS)

The hypothetical nonlocal box (NLB) proposed by Popescu and Rohrlich allows two spatially separated parties, Alice and Bob, to exhibit stronger than quantum correlations. If the generated correlations are weak, they can sometimes be distilled into a stronger correlation by repeated applications of the NLB. Motivated by the limited distillability of NLBs, we initiate here a study of the distillation of correlations for nonlocal boxes that output quantum states rather than classical bits (qNLBs). We propose a new protocol for distillation and show that it asymptotically distills a class of correlated quantum nonlocal boxes to the value (1)/(2)(3? {3}+1) ? 3.098076, whereas in contrast, the optimal non-adaptive parity protocol for classical nonlocal boxes asymptotically distills only to the value 3.0. We show that our protocol is an optimal non-adaptive protocol for 1, 2 and 3 qNLB copies by constructing a matching dual solution for the associated primal semidefinite program (SDP). We conclude that qNLBs are a stronger resource for nonlocality than NLBs. The main premise that develops from this conclusion is that the NLB model is not the strongest resource to investigate the fundamental principles that limit quantum nonlocality. As such, our work provides strong motivation to reconsider the status quo of the principles that are known to limit nonlocal correlations under the framework of qNLBs rather than NLBs.

Høyer, Peter; Rashid, Jibran

2013-06-01

437

27 CFR 17.162 - Receipt of distilled spirits.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Receipt of distilled spirits. 17.162 Section 17.162 Alcohol...LIQUORS DRAWBACK ON TAXPAID DISTILLED SPIRITS USED IN MANUFACTURING NONBEVERAGE PRODUCTS...Records § 17.162 Receipt of distilled spirits. (a) Distilled spirits...

2010-04-01

438

Packing Schemes for Gang Scheduling  

Microsoft Academic Search

. Jobs that do not require all processors in the system can bepacked together for gang scheduling. We examine accounting traces fromseveral parallel computers to show that indeed many jobs have small sizesand can be packed together. We then formulate a number of such packingalgorithms, and evaluate their effectiveness using simulations based onour workload study. The results are that two

Dror G. Feitelson

1996-01-01

439

Wire and Packing Tape Sandwiches  

ERIC Educational Resources Information Center

In this article, the author describes how students can combine craft wire with clear packing tape to create a two-dimensional design that can be bent and twisted to create a three-dimensional form. Students sandwich wire designs between two layers of tape. (Contains 1 online resource.)

Rabinowitz, Sandy

2009-01-01

440

Disk packings and planar separators  

Microsoft Academic Search

We demonstrate that the geometric separator algorithm of Miller, Teng, Thurston, and Vavasis finds a 3\\/4-separator of size 1.84+ for every n node planar graph. Our bound is derived from an analysis of disk packings on the sphere,

Daniel A. Spielmant; Shang-Hua Teng

1996-01-01

441

Mystery Pellets ClassPack  

NSDL National Science Digital Library

Using Picture-Perfect Science Lessons in your classroom is easier than ever! NSTA's ClassPacks, each sufficient for a class of 28 students, are lesson-specific collections of materials--an unmatched time-saver and a great deal. This Cla

2010-04-19

442

Mirror, Mirror ClassPack  

NSDL National Science Digital Library

Using More Picture-Perfect Science Lessons: Using Children's Books to Guide Inquiry, K-4 in your classroom is easier than ever! NSTA's ClassPacks, each sufficient for a class of 28 students, are lesson-specific collections of materials--an unmatche

2010-04-25

443

Imaginative Inventions ClassPack  

NSDL National Science Digital Library

Using More Picture-Perfect Science Lessons: Using Children's Books to Guide Inquiry, K-4 in your classroom is easier than ever! NSTA's ClassPacks, each sufficient for a class of 28 students, are lesson-specific collections of materials--an unmatche

2010-04-25

444

The Design & Planning Games Pack.  

ERIC Educational Resources Information Center

Over the next 10 months, five sections of a pack of environmental exercises will be presented (Houses Game, Planning Game, Building Designs, Planning Enquiry, Future Communities). This introduction (which includes instructions and materials for the Houses Game) suggests why such exercises are needed and describes problems they will help with.…

Bishop, Jeff; Russell, Graham

1982-01-01

445

Effects of Low-Conductivity Regions Near Grain-to-Grain Contacts on Early Colloid Breakthrough at the Column Scale  

Microsoft Academic Search

Effects of fluid velocity (2 to 60 m day-1) on bulk transport of carboxylate-modified microspheres (5.0mum) was investigated using saturated sand (450mum)-packed columns and pore-scale colloid movement was observed in glass bead (3mm)-packed flow-cells. At all flow rates, the colloid peak emerged from columns approximately 0.1 pore volume earlier than the dissolved conservative tracer, suggesting a consistent pore volume from

N. Ochiai; M. Dragila

2007-01-01

446

Sugarcane bagasse as alternative packing material for biofiltration of benzene polluted gaseous streams: a preliminary study  

Microsoft Academic Search

Removal of benzene vapor from gaseous streams was studied in two identically sized lab-scale biofiltration columns: one filled with a mixture of raw sugarcane bagasse and glass beads, and the other one packed with a mixture of ground sugarcane bagasse and glass beads, in the same volume ratio, as filter materials. Separate series of continuous tests were performed, in parallel,

L. Sene; A. Converti; M. G. A. Felipe; M. Zilli

2002-01-01

447

A packed bed dehumidifier\\/regenerator for solar air conditioning with liquid desiccants  

Microsoft Academic Search

A packed column air-liquid contactor has been studied in application to air dehumidification and regeneration in solar air conditioning with liquid desiccants. A theoretical model has been developed to predict the performance of the device under various operating conditions. Computer simulations based on the model are presented which indicate the practical range of air to liquid flux ratios and associated

H. M. Factor; G. Grossman

1980-01-01

448

Acid gas absorption in trickle flow columns—Modelling of the residence time distribution of a pilot plant  

Microsoft Academic Search

A simple mathematical model has been developed and validated for the dynamic behaviour of a pilot plant absorber with random packing (stainless steel construction, column diameter: 0.08m, height of packing zone: 1.3m, random packing: 15mm ceramic spheres). The model is based upon film theory, axial dispersion, and rate enhancement. Simplifications are made which are justified for the conditions of the

Tobias Pröll; Teodor Todinca; Marcel ?uta; Anton Friedl

2007-01-01

449

Flow characterization in a gas-liquid column: application to a bioscrubber for the deodorization of waste gases  

Microsoft Academic Search

The flow pattern of a countercurrent gas-liquid packed column is characterized for gas and liquid phases. Three packing materials are used (10 mm ceramic Raschig rings, 16 mm polypropylene Pall rings and 45 mm× 18 mm polypropylene Spiralpac) and various operating conditions are applied. A first approach consists in the study of pressure drops. On the one hand, this study

P. Humeau; J. N. Baléo; F. Raynaud; J. Bourcier; P. Le Cloirec

2000-01-01

450

Substituting Wet Distillers Grains or Condensed Distillers Solubles for Corn Grain in Finishing Diets for Yearling Heifers  

Microsoft Academic Search

A feeding trial was conducted with 790-lb yearling heifers fed an average of 121 days to evaluate replacing cracked corn and supplemental urea with wet distillers grains or condensed distillers solubles. Wet distillers grains were evaluated at 16%, 28% and 40% of diet dry matter. Condensed distillers solubles were added at 6.5% of diet dry matter. Control diets were supplemented

Allen Trenkle

1997-01-01

451

Processing of X-ray tomographic images: A procedure adapted for the analysis of phase distribution in MellapakPlus 752.Y and Katapak-SP packings  

Microsoft Academic Search

We developed a practical methodology to face common problems encountered in the analysis of tomographic images to get quantitative information on phase distributions in gas liquid contacting columns packed with complex metallic packings. In the present study, the procedure was developed and validated for MellapakPlus 752.Y and Katapak-SP packings, but it may be applied to any type of metallic or

A. Viva; S. Aferka; E. Brunazzi; P. Marchot; M. Crine; D. Toye

2011-01-01

452

The impact of column connection on band broadening in very high pressure liquid chromatography.  

PubMed

A series of experiments was conducted to evaluate the degree of band broadening in very high pressure LC due to column connections. Different column manufacturers use slightly different designs for their column fittings. If the same column connections are repeatedly used to attach columns of different origins, different void volumes form between capillary tubes and column inlets. An Agilent Ultra Low Dispersion Kit (tubing id 75 ?m) was installed on an Agilent Infinity 1290 ultra HPLC and used to connect successively an Agilent, a Phenomenex, and a Waters column. A series of uracil (unretained) samples were injected and eluted at a wide range of flow rates with a water/acetonitrile mixture as eluent. In order to determine the variance contribution from column connections as accurately as possible a nonretained probe compound was selected because the variance contribution from the column is the smallest for analytes, which have very low k values. Yet, this effect still has an impact on the resolution for moderately retained compounds (k > 2) for narrow-bore columns packed with fine particles, since variance contributions are additive for linear chromatographic systems. Each injection was replicated five times under the same experimental conditions. Then NanoViper column connections (tubing id 75 ?m) were used and the same injections were made. This system was designed to minimize connection void volumes for any column. Band variances were calculated as the second central moment of elution peaks and used to assess the degree of band broadening due to the column connections. Band broadening may increase from 3.8 to 53.9% when conventional metal ferrules were used to join columns to connection sites. The results show that the variance contribution from improper connections can generate as much as 60.5% of the total variance observed. This demonstrates that column connections can play a larger role than the column packing with respect to band dispersion. PMID:23900740

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Guiochon, Georges

2013-09-01

453

Particle packing from an earth science viewpoint  

NASA Astrophysics Data System (ADS)

Particle packings are relevant to many aspects of the Earth sciences, and there is a long history of the study of packings from an Earth science viewpoint. Packings have also been studied in connection with other subjects and disciplines. Allen (1982) produced a major review which provides a solid base for Earth science related studies. This review complements Allen's work and in particular focuses on advances in the study of random packings over the last ten years. Transitions from packing to packing may be as important as the packings themselves, and possibly easier to model. This paper places emphasis on certain neglected works, in particular Morrow and Graves (1969) and the packing transition envelope, Kahn (1956) and the measurement of packing parameters, Griffiths (1962) on packings in one-dimension, and Getis and Boots (1978) on packings in two dimensions. Certain packing problems are relevant to current areas of study including structure collapse in loess (hydroconsolidation), flowslides in very sensitive soils, wind erosion, jewel quality in opals and the structure and functions of sand dunes. The region where interparticle forces become active (particles < 200 ?m) is considered and the implications for packing are examined.

Rogers, C. D. F.; Dijkstra, T. A.; Smalley, I. J.

1994-04-01

454

Polymer-coated fibrous materials as the stationary phase in packed capillary gas chromatography.  

PubMed

Synthetic polymer filaments have been introduced as the support material in packed capillary gas chromatography (GC). The filaments of the heat-resistant polymers, Zylon, Kevlar, Nomex, and Technora, were longitudinally packed into a short fused-silica capillary, followed by the conventional coating process for open-tubular GC columns. The separation of several test mixtures such as n-alkylbenzenes and n-alkanes was carried out with these polymer-coated fiber-packed capillary columns. With the coating by various polymeric materials on the surface of these filaments, the retentivity was significantly improved over the parent fiber-packed column (without polymer coating) as well as a conventional open-tubular capillary of the same length. The results demonstrated a good combination of Zylon as the support and poly(dimethylsiloxane)-based materials as the coating liquid-phase for the successful GC separation of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while successful applications for other separations such as poly(ethylene glycol) coating for the separation of alcohols were also obtained. From the results it has been suggested that the selectivity of the fiber-packed column could be tuned by selecting different coating materials, indicating the promising possibility for a novel usage of fine fibrous polymers as the support material that can be combined with newly synthesized coating materials specially designed for particular separations. Taking advantage of good thermal stability of the fibers, the column temperature could be elevated to higher than 350 degrees C with the combination of a short metallic capillary. PMID:14710834

Saito, Yoshihiro; Tahara, Ai; Imaizumi, Motohiro; Takeichi, Tsutomu; Wada, Hiroo; Jinno, Kiyokatsu

2003-10-15

455

Water Vapor Permeability of Plastic Fast Packs.  

National Technical Information Service (NTIS)

The objective of this investigation was to perform nondestructive tests that quantitatively measured the water vapor permeability of a plastic (high density polyethylene) Type I Fast Pack design. The water vapor transmission rate (WVTR) of the new pack de...

J. A. Hincks

1978-01-01

456

Soil column leaching of pesticides.  

PubMed

In this review, I address the practical and theoretical aspects of pesticide soil mobility.I also address the methods used to measure mobility, and the factors that influence it, and I summarize the data that have been published on the column leaching of pesticides.Pesticides that enter the unsaturated soil profile are transported downwards by the water flux, and are adsorbed, desorbed, and/or degraded as they pass through the soil. The rate of passage of a pesticide through the soil depends on the properties of the pesticide, the properties of the soil and the prevailing environmental conditions.Because large amounts of many different pesticides are used around the world, they and their degradates may sometimes contaminate groundwater at unacceptable levels.It is for this reason that assessing the transport behavior and soil mobility of pesticides before they are sold into commerce is important and is one indispensable element that regulators use to assess probable pesticide safety. Both elementary soil column leaching and sophisticated outdoor lysimeter studies are performed to measure the leaching potential for pesticides; the latter approach more reliably reflects probable field behavior, but the former is useful to initially profile a pesticide for soil mobility potential.Soil is physically heterogeneous. The structure of soil varies both vertically and laterally, and this variability affects the complex flow of water through the soil profile, making it difficult to predict with accuracy. In addition, macropores exist in soils and further add to the complexity of how water flow occurs. The degree to which soil is tilled, the density of vegetation on the surface, and the type and amounts of organic soil amendments that are added to soil further affect the movement rate of water through soil, the character of soil adsorption sites and the microbial populations that exist in the soil. Parameters that most influence the rate of pesticide mobility in soil are persistence (DT50) of the pesticide, and its sorption/desorption(Koc) characteristics. These parameters may vary for the same pesticide from geographic site-to-site and with soil depth. The interactions that normally occur between pesticides and dissolved organic matter (DOM) or WDC are yet other factors that may complicate pesticide leaching behavior.The soil mobility of pesticides is normally tested both in the laboratory and in the field. Lab studies are initially performed to give researchers a preliminary appraisal of the relative mobility of a pesticide. Later, field lysimeter studies can be performed to provide more natural leaching conditions that emulate the actual field use pattern. Lysimeter studies give the most reliable information on the leaching behavior of a pesticide under field conditions, but these studies are time-consuming and expensive and cannot be performed everywhere. It is for this reason that the laboratory soil column leaching approach is commonly utilized to profile the mobility of a pesticide,and appraise how it behaves in different soils, and relative to other pesticides.Because the soil structure is chemically and physically heterogenous, different pesticide tests may produce variable DT50 and Koc values; therefore, initial pesticide mobility testing is undertaken in homogeneously packed columns that contain two or more soils and are eluted at constant flow rates. Such studies are done in duplicate and utilize a conservative tracer element. By fitting an appropriate mathematical model to the breakthrough curve of the conservative tracer selected,researchers determine key mobility parameters, such as pore water velocity, the column-specific dispersion coefficient, and the contribution of non equilibrium transport processes. Such parameters form the basis for estimating the probable transport and degradation rates that will be characteristic of the tested pesticide. Researchers also examine how a pesticide interacts with soil DOM and WDC, and what contribution from facilitated transport to mobility is made as a result of the effects of

Katagi, Toshiyuki

2013-01-01

457

Local purity distillation with bounded classical communication  

SciTech Connect

Local pure states are an important resource for quantum computing. The problem of distilling local pure states from mixed ones can be cast in an information theoretic paradigm. The bipartite version of this problem where local purity must be distilled from an arbitrary quantum state shared between two parties, Alice and Bob, is closely related to the problem of separating quantum and classical correlations in the state and in particular, to a measure of classical correlations called the one-way distillable common randomness. In Phys. Rev. A 71, 062303 (2005), the optimal rate of local purity distillation is derived when many copies of a bipartite quantum state are shared between Alice and Bob, and the parties are allowed unlimited use of a unidirectional dephasing channel. In the present paper, we extend this result to the setting in which the use of the channel is bounded. We demonstrate that in the case of a classical-quantum system, the expression for the local purity distilled is efficiently computable and provide examples with their tradeoff curves.

Krovi, Hari; Devetak, Igor [Communication Sciences Institute, University of Southern California, Los Angeles, California 90089 (United States)

2007-07-15

458

Cell aggregation: Packing soft grains  

NASA Astrophysics Data System (ADS)

Cellular aggregates may be considered as collections of membrane enclosed units with a pressure difference between the internal and external liquid phases. Cells are kept together by membrane adhesion and/or confined space compression. Pattern formation and, in particular, intercellular spacing have important roles in controlling solvent diffusion within such aggregates. A physical approach is used to study generic aspects of cellular packings in a confined space. Average material properties are derived from the free energy. The appearance of penetrating intercellular void channels is found to be critically governed by the cell wall adhesion mechanisms during the formation of dense aggregates. A fully relaxed aggregate efficiently hinders solvent diffusion at high hydrostatic pressures, while a small fraction (˜0.1) of adhesion related packing frustration is sufficient for breaking such a blockage even at high a pressure.

Åström, J. A.; Karttunen, M.

2006-06-01

459

Tritum recovery system from waste water of fusion reactor using CECE and cryogenic-wall thermal diffusion column  

SciTech Connect

A system for recovery of tritium in water has been proposed. The system is composed of CECE (Combined Electrolysis Chemical Exchange) and CTD (Cryogenic-wall Thermal Diffusion) columns. A design study was carried out for the two cases: the waste water processing in fusion facilities; and the tritium recovery from heavy water in a fission reactor in Japan. The size and power consumption of the system can greatly be reduced by using the CECE column than the system of WD (Water Distillation) columns. The operation and maintenance of the CTD column are quite easier than the CD (Cryogenic Distillation) column. The proposed system would be applicable for some cases such as the waste water processing in tritium facilities, where the processing flow rate is relatively small. 11 refs., 4 figs., 6 tabs.

Arita, T.; Yamanishi, T.; Iwai, Y.; Okuno, K. [Japan Atomic Energy Research Inst., Ibaraki (Japan); Kobayashi, N.; Yamamoto, I. [Nagoya Univ. (Japan)

1996-12-31

460

Ecology of southern ocean pack ice.  

PubMed

Around Antarctica the annual five-fold growth and decay of sea ice is the most prominent physical process and has a profound impact on marine life there. In winter the pack ice canopy extends to cover almost 20 million square kilometres--some 8% of the southern hemisphere and an area larger than the Antarctic continent itself (13.2 million square kilometres)--and is one of the largest, most dynamic ecosystems on earth. Biological activity is associated with all physical components of the sea-ice system: the sea-ice surface; the internal sea-ice matrix and brine channel system; the underside of sea ice and the waters in the vicinity of sea ice that are modified by the presence of sea ice. Microbial and microalgal communities proliferate on and within sea ice and are grazed by a wide range of proto- and macrozooplankton that inhabit the sea ice in large concentrations. Grazing organisms also exploit biogenic material released from the sea ice at ice break-up or melt. Although rates of primary production in the underlying water column are often low because of shading by sea-ice cover, sea ice itself forms a substratum that provides standing stocks of bacteria, algae and grazers significantly higher than those in ice-free areas. Decay of sea ice in summer releases particulate and dissolved organic matter to the water column, playing a major role in biogeochemical cycling as well as seeding water column phytoplankton blooms. Numerous zooplankton species graze sea-ice algae, benefiting additionally because the overlying sea-ice ceiling provides a refuge from surface predators. Sea ice is an important nursery habitat for Antarctic krill, the pivotal species in the Southern Ocean marine ecosystem. Some deep-water fish migrate to shallow depths beneath sea ice to exploit the elevated concentrations of some zooplankton there. The increased secondary production associated with pack ice and the sea-ice edge is exploited by many higher predators, with seals, seabirds and whales aggregating there. As a result, much of the Southern Ocean pelagic whaling was concentrated at the edge of the marginal ice zone. The extent and duration of sea ice fluctuate periodically under the influence of global climatic phenomena including the El Niño Southern Oscillation. Life cycles of some associated species may reflect this periodicity. With evidence for climatic warming in some regions of Antarctica, there is concern that ecosystem change may be induced by changes in sea-ice extent. The relative abundance of krill and salps appears to change interannually with sea-ice extent, and in warm years, when salps proliferate, krill are scarce and dependent predators suffer severely. Further research on the Southern Ocean sea-ice system is required, not only to further our basic understanding of the ecology, but also to provide ecosystem managers with the information necessary for the development of strategies in response to short- and medium-term environmental changes in Antarctica. Technological advances are delivering new sampling platforms such as autonomous underwater vehicles that are improving vastly our ability to sample the Antarctic under sea-ice environment. Data from such platforms will enhance greatly our understanding of the globally important Southern Ocean sea-ice ecosystem. PMID:12154613

Brierley, Andrew S; Thomas, David N

2002-01-01

461

Comparison of Advanced Distillation Control Methods, Final Technical Report  

SciTech Connect

Detailed dynamic simulations of three industrial distillation columns (a propylene/propane splitter, a xylene/toluene column, and a depropanizer) have been used to evaluate configuration selections for single-ended and dual-composition control, as well as to compare conventional and advanced control approaches. In addition, a simulator of a main fractionator was used to compare the control performance of conventional and advanced control. For each case considered, the controllers were tuned by using setpoint changes and tested using feed composition upsets. Proportional Integral (PI) control performance was used to evaluate the configuration selection problem. For single ended control, the energy balance configuration was found to yield the best performance. For dual composition control, nine configurations were considered. It was determined that the use of dynamic simulations is required in order to identify the optimum configuration from among the nine possible choi