Science.gov

Sample records for related bed agglomeration

  1. Bed material agglomeration during fluidized bed combustion

    SciTech Connect

    Brown, R.C.; Dawson, M.R.; Noble, S.

    1993-02-01

    The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.

  2. Bed material agglomeration during fluidized bed combustion. Technical progress report, September 30, 1992--December 31, 1992

    SciTech Connect

    Brown, R.C.; Dawson, M.R.; Noble, S.

    1993-02-01

    The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.

  3. Agglomeration in a fluidized bed using multiple jet streams

    SciTech Connect

    Rehmat, A.; Abbasian, J. ); Kothari, M.; Hariri, H.; Arastoopour, H. )

    1992-01-01

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

  4. Agglomeration in a fluidized bed using multiple jet streams

    SciTech Connect

    Rehmat, A.; Abbasian, J.; Kothari, M.; Hariri, H.; Arastoopour, H.

    1992-12-31

    Tests were conducted to determine the overall temperature distribution, temperature in the vicinity of the jets, and the rate of agglomeration in a fluidized bed containing multiple jet streams. Agglomeration of ash during coal gasification increases carbon utilization efficiency considerably. The agglomeration requires a fluidized-bed reactor with a specially designed distributor equipped with a jet to yield a hot zone confined within the bed. The rate of agglomeration depends upon the size and the intensity of the zone. This rate, and hence the unit capacity, could be increased by adding multiple jets to the distributor. The purpose of this study was to verify this phenomenon. The temperature distribution inside the agglomerating fluidized-bed reactor with a single jet was studied by Hariri et al. Various parameters were involved in agglomeration phenomena -- bed material, fluidization velocity, bed temperature, jet velocity, jet temperature, bed geometry, and distributor geometry. Controlled agglomerates were produced in the fluidized bed when a sloped gas distributor consisting of a central jet and a porous plate was used. Gas at temperatures above the melting temperature of a bed material was introduced into the jet and gas at temperatures below the softening temperature was introduced into the distributor. The rate of agglomerate formation was significantly influenced by an increase in either jet air or auxiliary (grid) air temperature. The extent of agglomeration also depended strongly upon the volume of the hot zone confined within the isotherms with temperatures higher than the melting point of the bed material.

  5. Agglomeration-Free Distributor for Fluidized Beds

    NASA Technical Reports Server (NTRS)

    Ouyang, F.; Sinica, A.; Levenspiel, O.

    1986-01-01

    New gas distributor for fluidized beds prevents hot particles from reacting on it and forming hard crust. In reduction of iron ore in fluidized bed, ore particles do not sinter on distributor and perhaps clog it or otherwise interfere with gas flow. Distributor also relatively cool. In fluidized-bed production of silicon, inflowing silane does not decompose until within bed of hot silicon particles and deposits on them. Plates of spiral distributor arranged to direct incoming gas into spiral flow. Turbulence in flow reduces frequency of contact between fluidized-bed particles and distributor.

  6. Bed material agglomeration during fluidized bed combustion. Technical progress report, January 1, 1993--March 31, 1993

    SciTech Connect

    Brown, R.C.; Dawson, M.R.; Noble, S.D.

    1993-04-01

    The purpose of this project is to determine the physical and chemical reactions which lead to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. A survey of agglomeration and deposit formation in industrial fluidized bed boilers is in progress. Preliminary results indicate that at least five boilers were experiencing some form of bed material agglomeration. In these instances it was observed that large particles were forming within the bed which were larger that the feed. Four operators could confirm that the larger bed particles had formed due to bed particles sticking together or agglomerating. Deposit formation was reported at nine sites with these deposits being found most commonly at coal feed locations and in cyclones. Other deposit locations included side walls and return loops. Examples of these agglomerates and deposits have been received from five of the surveyed facilities. Also during this quarter, a bulk sample of Illinois No. 6 coal was obtained from the Fossil Energy Program at Ames Laboratory here at Iowa State University and prepared for combustion tests. This sample was first ground to a top-size of 3/8`` using a jaw crusher then a size fraction of 3/8`` {times} 8 (US mesh) was then obtained by sieving using a Gilson Test-Master. This size fraction was selected for the preliminary laboratory-scale experiments designed to simulate the dense bed conditions that exist in the bottom of CFB combustors. To ensure uniformity of fuel composition among combustion runs, the sized coal was riffled using, a cone and long row method and stored in bags for each experiment. During this quarter additional modifications were made to achieve better control of fluidization regimes and to aid in monitoring the hydrodynamic and chemical conditions within the reactor.

  7. Analysis of atmospheric fluidized bed combustion agglomerates. Final report

    SciTech Connect

    Perkins, D. III; Brekke, D.W.; Karner, F.R.

    1984-04-01

    Chemical and textural studies of AFBC agglomerates have revealed detailed information regarding the mechanisms of agglomeration. The formation of agglomerates in a silica sand bed can be described by a four step process: initial ash coatings of quartz grains; thickening of ash coatings and the formation of nodules; cementation of nodules to each other by a sulfated aluminosilicate matrix; and partial or complete melting of eutectic compositions to produce a sticky glass phase between grains and along fractures. Once agglomeration has begun, large scale solidification and restricted flow within the bed will lead to hot spots, wholesale melting and further agglomeration which ultimately forces a shutdown. Standard operating temperatures during normal AFBC runs come quite close to, or may actually exceed, the minimum temperatures for eutectic melting of the silicate phases in the coal and standard bed materials. The partially melted material may be expected to lead to the formation of dense, sticky areas within the bed, and the formation of hot spots which further exacerbate the problem. Ultimately, large scale bed agglomeration will result. Attempts to eliminate agglomeration by removal of sodium via an ion exchange process have yielded encouraging results. A second approach, used to raise melting temperatures within the bed, has been to use bed materials that may react with low-temperature minerals to produce high-temperature refractory phases such as mullite or other alkali and alkali-earth alumino-silicates.

  8. Review of ash agglomeration in fluidized bed gasifiers

    SciTech Connect

    Matulevicius, E.S.; Golan, L.P.

    1984-07-01

    The purpose of this study is to review the data and mathematical models which describe the phenomena involved in the agglomeration of ash in fluidized bed coal gasifiers (FBG). Besides highlighting the data and theoretical models, this review lists areas where there is a lack of information regarding the actual mechanisms of agglomeration. Also, potential areas for further work are outlined. The work is directed at developing models of agglomeration which could be included in computer codes describing fluidized bed gasifier phenomena, e.g., FLAG and CHEMFLUB which have been developed for the US Department of Energy. 134 references, 24 figures, 13 tables.

  9. Reduced bed agglomeration by co-combustion biomass with peat fuels in a fluidized bed

    SciTech Connect

    Karin Lundholm; Anders Nordin; Marcus Oehman; Dan Bostroem

    2005-12-01

    Fluidized bed combustion is an energy conversion technology that is very suitable for biomass combustion because of its fuel flexibility and low process temperatures. However, agglomeration of bed material may cause severe operating problems. To prevent or at least reduce this, peat has been suggested as an additive to the main fuels. Nevertheless, the characteristics of peat fuels vary and there is limited information of the effect of different peat fuels and of the mechanisms behind the agglomeration prevention. The objectives of the present work were therefore to: (I) quantify the potential positive effect by co-combustion peat with forest fuels in terms of initial agglomeration temperatures; (ii) determine the amount of peat fuel that is needed to significantly reduce the agglomeration tendencies; and, if possible, (iii) elucidate the governing mechanisms. The results showed that all peat fuels prevented agglomeration in the studied interval of 760-1020{sup o}C and even as little as 5% peat fuel was found to have significant effects. The results also indicated that the mechanism of the agglomeration prevention varies between different peat fuels. Possible mechanisms are the minerals in the peat fuel retain alkali, which then is either elutriated up from the bed or captured in the bed; calcium and other refractory elements increase the melting temperature and thereby counteract the melting of alkali; and sulfur reacts with alkali metals and the alkali sulfates is either elutriated up from the bed or prevents agglomeration by increased melting temperature and lowered viscosity. Results from elemental analysis of the coating on bed particles showed that all mixtures with peat fuel resulted in a decreased or unchanged fraction of potassium and an increased fraction of aluminum in the coatings. The results also indicated a complex relationship between the fuel inorganic contents and the agglomeration process. 21 refs., 6 figs., 5 tabs.

  10. Bed material agglomeration during fluidized bed combustion. Technical progress report, January 1, 1995--March 31, 1995

    SciTech Connect

    Brown, R.C.; Dawson, M.R.; Smeenk, J.L.

    1995-04-01

    Experiments performed support the hypothesis that a reducing atmosphere during fluidized bed coal combustion contributes to the formation of agglomerates. Reducing conditions are imposed by controlling the amount of combustion air supplied to the combustor, 50% of theoretical in these experiments. These localized reducing conditions may arise from either poor lateral bed mixing or oxygen-starved conditions due to the coal feed locations. Deviations from steady-state operating conditions in bed pressure drop may be used to detect agglomerate formation. Interpretation of the bed pressure drop was made more straightforward by employing a moving average difference method. During steady-state operation, the difference between the moving point averages should be close to zero, within {plus_minus}0.03 inches of water. Instability within the combustor, experienced once agglomerates begin to form, can be recognized as larger deviations from zero, on the magnitude of {plus_minus}0.15 inches of water.

  11. A MODEL FOR FINE PARTICLE AGGLOMERATION IN CIRCULATING FLUIDIZED BED ABSORBERS

    EPA Science Inventory

    A model for fine particle agglomeration in circulating fluidized bed absorbers (CFBAS) has been developed. It can model the influence of different factors on agglomeration, such as the geometry of CFBAs, superficial gas velocity, initial particle size distribution, and type of ag...

  12. Preparation of sustained release matrix pellets by melt agglomeration in the fluidized bed: influence of formulation variables and modelling of agglomerate growth.

    PubMed

    Pauli-Bruns, Anette; Knop, Klaus; Lippold, Bernhard C

    2010-03-01

    The one-step preparation of sustained release matrix pellets, using a melting procedure in a fluidized bed apparatus, was tested in a 2(3) full factorial design of experiments, using microcrystalline wax as lipophilic binder, theophylline as model drug and talc as additional matrix forming agent. The three influence parameters were (A) size of binder particles, (B) fraction of theophylline in solid particles and (C) fraction of microcrystalline wax in formulation. The response variables were agglomerate size and size distribution, dissolution time, agglomerate crush resistance, sphericity, yield and porosity. Nearly spherical pellets comprising a smooth, closed surface could be obtained with the used method, exhibiting the hollow core typical for the immersion and layering mechanism. The reproducibility was very good concerning all responses. The size of agglomerates is proportional to the size of the binder particles, which serve as cores for pellet formation in the molten state in the fluidized bed. Additionally, the agglomerate size is influenced by the volume of the solid particles in relation to the binder particles, with more solid particles leading to larger agglomerates and vice versa. Dissolution times vary in a very wide range, resulting from the interplay between amount of drug in relation to the meltable matrix substance microcrystalline wax and the non-meltable matrix substance talc. The change of binder particle size does not lead to a structural change of the matrix; both dissolution times and porosity are not significantly altered. Agglomerate crush resistance is low due to the hollow core of the pellets. However, it is significantly increased if the volume fraction of microcrystalline wax in the matrix is high, which means that the matrix is mechanically better stabilized. A theoretical model has been established to quantitatively explain agglomerate growth and very good accordance of the full particle size distributions between predicted and

  13. Experimental development of a two-stage fluidized-bed/cyclonic agglomerating incinerator

    SciTech Connect

    Mensinger, M.C.; Rehmat, A.; Bryan, B.G.; Lau, F.S. ); Shearer, T.L. ); Duggan, P.A. )

    1991-01-01

    The Institute of Gas Technology (IGT) is conducting an experimental program to develop and test through pilot-plant scale of operation, IGT's two-stage fluidized-bed/cyclonic agglomerating incinerator (TSI). The TSI is based on combining the fluidized-bed agglomeration/gasification technology and the cyclonic combustion/incineration technology, which have been developed at IGT over many years. The TSI is a unique and extremely flexible combustor that can operate over a wide range of conditions in the fluidized-bed first stage from low temperature (desorption) to high temperature (agglomeration) including gasification of high-Btu wastes. The TSI can easily and efficiently destroy solid, liquid and gaseous organic wastes, while containing solid inorganic contaminants within an essentially non-leachable glassy matrix, suitable for disposal in an ordinary landfill. This paper presents the results of tests conducted in a batch, fluidized-bed bench-scale unit (BSU) with commercially available clean'' top soil and the same soil spiked with lead and chromium compounds. The objectives of these tests were to determine the operating conditions necessary to achieve soil agglomeration and to evaluate the leaching characteristics of the soil agglomerates formed. 7 refs., 7 figs., 6 tabs.

  14. Gasification of palm empty fruit bunch in a bubbling fluidized bed: a performance and agglomeration study.

    PubMed

    Lahijani, Pooya; Zainal, Zainal Alimuddin

    2011-01-01

    Gasification of palm empty fruit bunch (EFB) was investigated in a pilot-scale air-blown fluidized bed. The effect of bed temperature (650-1050 °C) on gasification performance was studied. To explore the potential of EFB, the gasification results were compared to that of sawdust. Results showed that maximum heating values (HHV) of 5.37 and 5.88 (MJ/Nm3), dry gas yield of 2.04 and 2.0 (Nm3/kg), carbon conversion of 93% and 85 % and cold gas efficiency of 72% and 71 % were obtained for EFB and sawdust at the temperature of 1050 °C and ER of 0.25. However, it was realized that agglomeration was the major issue in EFB gasification at high temperatures. To prevent the bed agglomeration, EFB gasification was performed at temperature of 770±20 °C while the ER was varied from 0.17 to 0.32. Maximum HHV of 4.53 was obtained at ER of 0.21 where no agglomeration was observed. PMID:20980143

  15. Fluidized-bed catalytic coal-gasification process. [US patent; pretreatment to minimize agglomeration

    DOEpatents

    Euker, C.A. Jr.; Wesselhoft, R.D.; Dunkleman, J.J.; Aquino, D.C.; Gouker, T.R.

    1981-09-14

    Coal or similar carbonaceous solids impregnated with gasification catalyst constituents are oxidized by contact with a gas containing between 2 vol % and 21 vol % oxygen at a temperature between 50 and 250/sup 0/C in an oxidation zone and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone at an elevated pressure. The oxidation of the catalyst impregnated solids under these conditions insures that the bed density in the fluidized bed gasification zone will be relatively high even though the solids are gasified at elevated pressure and temperature.

  16. Bed Agglomeration During the Steam Gasification of a High Lignin Corn Stover Simultaneous Saccharification and Fermentation (SSF) Digester Residue

    SciTech Connect

    Howe, Daniel T.; Taasevigen, Danny J.; Gerber, Mark A.; Gray, Michel J.; Fernandez, Carlos A.; Saraf, Laxmikant; Garcia-Perez, Manuel; Wolcott, Michael P.

    2015-11-13

    This research investigates the bed agglomeration phenomena during the steam gasification of a high lignin residue produced from the simultaneous saccharification and fermentation (SSF) of corn stover in a bubbling fluidized bed. The studies were conducted at 895°C using alumina as bed material. Biomass was fed at 1.5 kg/hr, while steam was fed to give a velocity equal to 2.5 times the minimum fluidization velocity, with a steam/carbon ratio of 0.9. The pelletized feedstock was co-fed with a cooling nitrogen stream to mitigate feed line plugging issues. Tar production was high at 50.3 g/Nm3, and the fraction of C10+ compounds was greater than that seen in the gasification of traditional lignocellulosic feedstocks. Carbon closures over 94 % were achieved for all experiments. Bed agglomeration was found to be problematic, indicated by pressure drop increases observed below the bed and upstream of the feed line. Two size categories of solids were recovered from the reactor, +60 mesh and -60 mesh. After a 2.75-hour experiment, 61.7 wt % was recovered as -60 mesh particles and 38.2 wt% of the recovered reactor solids were +60 mesh. A sizeable percentage, 31.8 wt%, was +20 mesh. The -60 mesh particles were mainly formed by the initial bed material (Al2O3). Almost 50 wt. % of the + 20 mesh particles was found to be formed by organics. The unreacted carbon remaining in the reactor resulted in a low conversion rate to product gas. ICP-AES, SEM, SEM-EDS, and XRD confirmed that the large agglomerates (+ 20 mesh) were not encapsulated bed material but rather un-gasified feedstock pellets with sand particles attached to it.

  17. Development of advanced fluid-bed agglomeration and cyclonic incineration for simultaneous waste disposal and energy recovery

    SciTech Connect

    Rehmat, A.; Khinkis, M.

    1991-01-01

    The Institute of Gas Technology (IGT) is currently developing a two-stage fluidized-bed/cyclonic agglomerating incineration system for waste disposal that is based on combining the fluidized-bed agglomeration/incineration and cyclonic combustion techologies. Both technologies have been developed individually at IGT over many years. This combination has resulted in a unique and extremely flexible incinerator for solid, liquid, and gaseous wastes including municipal sludges. The system can operate over a wide range of conditions in the first stage, from low temperature (desorption) to high temperature (agglomeration), including gasification of wastes. In the combined system, solid, liquid, and gaseous organic wastes are incinerated with ease and great efficiency (>99.99% destruction and removal efficiency (DRE)), while solid inorganic contaminants contained within a glassy matrix are rendered benign and suitable for disposal in an ordinary landfill. The heat generated within the incinerator can be recovered using the state-of-the-art boilers. The development of the two-stage incinerator is a culmination of extensive research and development efforts on each stage of the incinerator. The variety of data obtained with solid, liquid, and gaseous wastes for both stages includes agglomeration of ash, incineration and reclamation of used blast grit and foundry sand, partial combustion of carbonaceous fuels, in-situ desulfurization, combustion of low-Btu gases, incineration of industrial wastewater, and incineration of carbon tetrachloride. 5 refs., 7 figs., 12 tabs.

  18. Study of composition change and agglomeration of flue gas cleaning residue from a fluidized bed waste incinerator.

    PubMed

    Lievens, P; Verbinnen, B; Bollaert, P; Alderweireldt, N; Mertens, G; Elsen, J; Vandecasteele, C

    2011-10-01

    Blocking of the collection hoppers of the baghouse filters in a fluidized bed incinerator for co-incineration of high calorific industrial solid waste and sludge was observed. The composition of the flue gas cleaning residue (FGCR), both from a blocked hopper and from a normal hopper, was investigated by (differential) thermogravimetric analysis, quantitative X-ray powder diffraction and wet chemical analysis. The lower elemental carbon concentration and the higher calcium carbonate concentration of the agglomerated sample was the result of oxidation of carbon and subsequent reaction of CO2 with CaO. The evolved heat causes a temperature increase, with the decomposition of CaOHCl as a consequence. The formation of calcite and calcium chloride and the evolution of heat caused agglomeration of the FGCR. Activated lignite coke was replaced by another adsorption agent with less carbon, so the auto-ignition temperature increased; since then no further block formation has occurred. PMID:22329155

  19. Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system: Topical report, Process analysis, FY 1983

    SciTech Connect

    1987-07-31

    KRW Energy Systems, Inc., is engaged in the continuing development of a pressurized, fluidized-bed gasification process at its Waltz Mill Site in Madison, Pennsylvania. The overall objective of the program is to demonstrate the viability of the KRW process for the environmentally-acceptable production of low- and medium-Btu fuel gas from a variety of fossilized carbonaceous feedstocks and industrial fuels. This report presents process analysis of the 24 ton-per-day Process Development Unit (PDU) operations and is a continuation of the process analysis work performed in 1980 and 1981. Included is work performed on PDU process data; gasification; char-ash separation; ash agglomeration; fines carryover, recycle, and consumption; deposit formation; materials; and environmental, health, and safety issues. 63 figs., 43 tabs.

  20. Development of methods to predict agglomeration and deposition in fluidized-bed combustion systems (FBCS). Topical report

    SciTech Connect

    Mann, M.D.; Henderson, A.K.; Swanson, M.L.; Allan, S.E.

    1996-02-01

    The successful design and operation of advanced combustion systems require the ability to control and mitigate ash-related problems. The major ash-related problems are slag flow control, slag attack on the refractory, ash deposition on heat-transfer surfaces, corrosion and erosion of equipment materials, and emissions control. These problems are the result of physical and chemical interactions of the fuels, bed materials, and system components. The interactions that take place and ultimately control ash behavior in fluidized-bed combustion (FBC) systems are controlled by the abundance and association of the inorganic components in coal and by the system conditions. Because of the complexity of the materials and processes involved, the design and operations engineer often lacks the information needed to predict ash behavior and reduce ash-related problems. The deposition of ashes from the fluidized bed combustion of lignite and petroleum coke is described in this paper.

  1. Control methods for mitigating biomass ash-related problems in fluidized beds.

    PubMed

    Vamvuka, D; Zografos, D; Alevizos, G

    2008-06-01

    Embodiment of biomass combustion technologies in the Cretan energy system will play an important role and will contribute to the local development. The main biomass fuels of Crete are the agricultural residues olive kernel and olive tree wood. Future applications of these biofuels may create, among others, operational problems related to ash effects. In this regard, the thermal behavior of the ashes during lab-scale fluidized bed combustion tests was examined, in terms of slagging/fouling and agglomeration of bed material. Control methodologies for mitigating ash problems were applied, such as leaching the raw fuels with water and using different mineral additives during combustion. The ashes and the bed material were characterized in terms of mineralogical, chemical and morphological analyses and the slagging/fouling and agglomeration propensities were determined. The results showed that fly ashes were rich in Ca, Si and Fe minerals and contained substantial amounts of alkali, falling within the range of "certain or probable slagging/fouling". Leaching of the raw fuels with water resulted in a significant reduction of the problematic elements K, Na, Cl and S in the fly ashes. The use of fuel additives decreased the concentrations of alkali and iron minerals in the fly ashes. With clay additives calcium compounds were enriched in the bottom ash, while with carbonate additives they were enriched in the fly ash. Fuel additives or water leaching reduced the slagging/fouling potential due to alkali. Under the conditions of the combustion tests, no signs of ash deposition or bed agglomeration were noticed. PMID:17826986

  2. ASSESSING RELATIVE BED STABILITY AND EXCESS FINE SEDIMENTS IN STREAMS

    EPA Science Inventory

    Excess fine sedimentation is recognized as a leading cause of water quality impairment in surface waters in the United States. We developed an index of Relative Bed Stability (RBS) that factors out natural controls on streambed particle size to allow evaluation of the role of hu...

  3. Unraveling bed slope from relative roughness in initial sediment motion

    NASA Astrophysics Data System (ADS)

    Prancevic, Jeff P.; Lamb, Michael P.

    2015-03-01

    Understanding incipient sediment transport is crucial for predicting landscape evolution, mitigating flood hazards, and restoring riverine habitats. Observations show that the critical Shields stress increases with increasing channel bed slope, and proposed explanations for this counterintuitive finding include enhanced form drag from bed forms, particle interlocking across the channel width, and large bed sediment relative to flow depth (relative roughness). Here we use scaled flume experiments with variable channel widths, bed slopes, and particle densities to separate these effects which otherwise covary in natural streams. The critical Shields stress increased with bed slope for both natural gravel (ρs = 2.65 g/cm3) and acrylic particles (ρs = 1.15 g/cm3), and adjusting channel width had no significant effect. However, the lighter acrylic particles required a threefold higher critical Shields stress for mobilization relative to the natural gravel at a fixed slope, which is unexpected because particle density is accounted for directly in the definition of Shields stress. A comparison with model predictions indicates that changes in local velocity and turbulence associated with increasing relative roughness for lighter materials are responsible for increasing the critical Shields stress in our experiments. These changes lead to concurrent changes in the hydraulic resistance and a nearly constant critical stream power value at initial motion. Increased relative roughness can explain much of the observed heightened critical Shields stresses and reduced sediment transport rates in steep channels and also may bias paleohydraulic reconstructions in environments with exotic submerged densities such as iron ore, pumice, or ice clasts on Titan.

  4. Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Third quarter progress report FY-1984, April 1-June 30, 1984

    SciTech Connect

    Not Available

    1986-01-31

    The overall objective of the KRW coal gasification program is to demonstrate the viability of the KRW pressurized, fluidized-bed, gasification system for the production of medium-Btu fuel gas for syngas, electrical power generation, chemical feedstocks, or industrial fuels and to obtain performance and scaleup data for the process and hardware. Progress reports are presented for the following tasks: (1) operation and maintenance of the process development unit (PDU); (2) modifications to the PDU; (3) cold flow scaleup facility; (4) advanced process design and analysis; and (5) laboratory support studies. For laboratory support studies, coal and/or char fines from Wyoming Sub C, Western Kentucky, Republic of South Africa (RSA), and Pittsburgh seam coals processed in the PDU were characterized for reactivity on a thermogravimetric analyzer. The average relative reactivity of the fines (-120 x +140 mesh) was found to be nearly the same as that for larger size distribution (18 x 60 mesh, -1.0 + 0.25 mm). This is consistent with the observations of studies reported in literature on carbon gasification reactions.

  5. Fuel agglomerates and method of agglomeration

    DOEpatents

    Wen, Wu-Wey

    1986-01-01

    Solid fuel agglomerates are prepared of particulate coal or other carbonaceous material with a binder having a high humic acid or humate salt content. The humic acid is extracted from oxidized carbonaceous material with a mild aqueous alkali solution of, for instance, ammonia. The particulate material is blended with the extract which serves as the binder for the agglomerates. The water-resistant agglomerates are formed such as by pelletizing, followed by drying to remove moisture and solidify the humic acid binder throughout the agglomerate.

  6. The Influence of Relative Submergence on the Near-bed Flow Field: Implications for Bed-load Transport

    NASA Astrophysics Data System (ADS)

    Cooper, J.; Tait, S.; Marion, A.

    2005-12-01

    the above tests. The overlap between this distribution and the measured velocities are used to estimate entrainment rates. Predicted entrainment rates increase with relative submergence, even for similar bed shear stress. Assuming bed-load rate is the product of entrainment rate and hop length, and that hop lengths are sensibly stable, suggests that transport rate has a dependence on relative submergence. This demonstrates that transport rate is not a direct function of average bed shear stress. The results describe a mechanism that will cause river channels with contrasting morphologies (and different relative submergence) but similar levels of average bed stress to experience different levels of sediment mobility. Chegini A. Tait S. Heald J. McEwan I. 2002 The development of an automated system for the measurement of near bed turbulence and grain motion. Proc. ASCE Conf. on Hydraulic Measurements and Experimental Methods, ISBN 0-7844-0655-3. Drake T.G. Shreve R.L. Dietrich W.E. Whiting P.J. Leopold L.B. 1988 Bedload transport of fine gravel observed by motion-picture photography, J. Fluid Mech., 192, 193-217. Heald J. McEwan I. Tait, S. 2004 Sediment transport over a flat bed in a unidirectional flow: simulations and validation, Phil. Trans. Roy. Soc. of London A, 362, 1973-1986. Nelson J.M. Shreve R.L. McLean S.R. Drake T.G. 1995 Role of near-bed turbulence structure in bed-load transport and bed form mechanics, Water. Res. Res., 31, 8, 2071-2086.

  7. Powder agglomeration in a microgravity environment

    NASA Technical Reports Server (NTRS)

    Cawley, James D.

    1994-01-01

    This is the final report for NASA Grant NAG3-755 entitled 'Powder Agglomeration in a Microgravity Environment.' The research program included both two types of numerical models and two types of experiments. The numerical modeling included the use of Monte Carlo type simulations of agglomerate growth including hydrodynamic screening and molecular dynamics type simulations of the rearrangement of particles within an agglomerate under a gravitational field. Experiments included direct observation of the agglomeration of submicron alumina and indirect observation, using small angle light scattering, of the agglomeration of colloidal silica and aluminum monohydroxide. In the former class of experiments, the powders were constrained to move on a two-dimensional surface oriented to minimize the effect of gravity. In the latter, some experiments involved mixture of suspensions containing particles of opposite charge which resulted in agglomeration on a very short time scale relative to settling under gravity.

  8. Advances in food powder agglomeration engineering.

    PubMed

    Cuq, B; Gaiani, C; Turchiuli, C; Galet, L; Scher, J; Jeantet, R; Mandato, S; Petit, J; Murrieta-Pazos, I; Barkouti, A; Schuck, P; Rondet, E; Delalonde, M; Dumoulin, E; Delaplace, G; Ruiz, T

    2013-01-01

    Food powders are used in everyday life in many ways and offer technological solutions to the problem of food production. The natural origin of food powders, diversity in their chemical composition, variability of the raw materials, heterogeneity of the native structures, and physicochemical reactivity under hydrothermal stresses contribute to the complexity in their behavior. Food powder agglomeration has recently been considered according to a multiscale approach, which is followed in the chapter layout: (i) at the particle scale, by a presentation of particle properties and surface reactivity in connection with the agglomeration mechanisms, (ii) at the mechanisms scale, by describing the structuration dynamics of agglomerates, (iii) at the process scale, by a presentation of agglomeration technologies and sensors and by studying the stress transmission mode in the powder bed, and finally (iv) by an integration of the acquired knowledge, thanks to a dimensional analysis carried out at each scale. PMID:23522795

  9. Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system: Phase 2, Final report, May 1, 1983-July 31, 1984

    SciTech Connect

    1987-09-15

    KRW Energy Systems Inc. is engaged in the development of a pressurized, fluidized-bed, gasification process at its Waltz Mill Site in Madison, Pennsylvania. The overall objective of the program is to demonstrate the viability of the KRW process for the environmentally acceptable production of low- and medium-Btu fuel gas from a variety of fossilized, carbonaceous feedstocks for electrical power generation, substitute natural gas, chemical feedstocks, and industrial fuels. This report covers Phase II of the contract period (May 1, 1983 to July 31, 1984) and is a continuation of the work performed in 1983 and reported in the Phase I final report, FE-19122-30. Included is work performed in fiscal 1983 to 1984 on PDU testing, process analysis, cold flow scaleup facility, process and component engineering and design, and laboratory support studies.

  10. Quantitative characterization of agglomerate abrasion in a tumbling blender by using the Stokes number approach.

    PubMed

    Willemsz, Tofan A; Nguyen, Tien Thanh; Hooijmaijers, Ricardo; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees

    2013-03-01

    Removal of microcrystalline cellulose agglomerates in a dry-mixing system (lactose, 100 M) predominantly occurs via abrasion. The agglomerate abrasion rate potential is estimated by the Stokes abrasion (StAbr) number of the system. The StAbr number equals the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. Basically, the StAbr number concept describes the blending condition of the dry-mixing system. The concept has been applied to investigate the relevance of process parameters on agglomerate abrasion in tumbling blenders. Here, process parameters such as blender rotational speed and relative fill volumes were investigated. In this study, the StAbr approach revealed a transition point between abrasion rate behaviors. Below this transition point, a blending condition exists where agglomerate abrasion is dominated by the kinetic energy density of the powder blend. Above this transition point, a blending condition exists where agglomerates show (undesirable) slow abrasion rates. In this situation, the blending condition is mainly determined by the high fill volume of the filler. PMID:23250711

  11. Multidimensional nature of fluidized nanoparticle agglomerates.

    PubMed

    de Martín, Lilian; Bouwman, Wim G; van Ommen, J Ruud

    2014-10-28

    We show that fluidized nanoparticle agglomerates are hierarchical fractal structures with three fractal dimensions: one characterizing sintered aggregates formed during nanoparticle synthesis, one that is also found in stored agglomerates and represents unbroken agglomerates, and one describing the large agglomerates broken during fluidization. This has been possible by using spin-echo small-angle neutron scattering-a relatively novel technique that, for the first time, allowed to characterize in situ the structure of fluidized nanoparticle agglomerates from 21 nm to ∼20 μm. The results show that serial agglomeration mechanisms in the gas phase can generate nanoparticle clusters with different fractal dimensions, contradicting the common approach that considers fluidized nanoparticle agglomerates as single fractals, in analogy to the agglomerates formed by micron-sized particles. This work has important implications for the fluidization field but also has a wider impact. Current studies deal with the formation and properties of clusters where the building blocks are particles and the structure can be characterized by only one fractal dimension. However, fluidized nanoparticle agglomerates are low-dimensional clusters formed by higher-dimensional clusters that are formed by low-dimensional clusters. This multifractality demands a new type of multiscale model able to capture the interplay between different scales. PMID:25313446

  12. Effect of biomass-sulfur interaction on ash composition and agglomeration for the co-combustion of high-sulfur lignite coals and olive cake in a circulating fluidized bed combustor.

    PubMed

    Varol, Murat; Atimtay, Aysel T

    2015-12-01

    This study aimed to investigate the effect of biomass-sulfur interaction on ash composition and agglomeration for the co-combustion of high-sulfur lignite coals and olive cake in a circulating fluidized bed combustor. The tests included co-combustion of 50-50% by wt. mixtures of Bursa-Orhaneli lignite+olive cake and Denizli-Kale lignite+olive cake, with and without limestone addition. Ash samples were subjected to XRF, XRD and SEM/EDS analyses. While MgO was high in the bottom ash for Bursa-Orhaneli lignite and olive cake mixture, Al2O3 was high for Denizli-Kale lignite and olive cake mixture. Due to high Al2O3 content, Muscovite was the dominant phase in the bottom ash of Denizli Kale. CaO in the bottom ash has increased for both fuel mixtures due to limestone addition. K was in Arcanite phase in the co-combustion test of Bursa/Orhaneli lignite and olive cake, however, it mostly appeared in Potassium Calcium Sulfate phase with limestone addition. PMID:26407346

  13. Granulation and Sludge Bed Stability in Upflow Anaerobic Sludge Bed Reactors in Relation to Surface Thermodynamics

    PubMed Central

    Thaveesri, J.; Daffonchio, D.; Liessens, B.; Vandermeren, P.; Verstraete, W.

    1995-01-01

    Adhesion of bacteria involved in anaerobic consortia was investigated in upflow anaerobic sludge bed reactors and was related to surface thermodynamics. The adhesion of hydrophilic cells appeared to be enhanced at a low liquid surface tension ((gamma)(infLV)), while the adhesion of hydrophobic cells was favored at a high (gamma)(infLV). Growth in protein-rich growth media resulted in low granular biomass yields; addition of polycations, such as poly-l-lysine and chitosan, increased the (gamma)(infLV) and the granular biomass yield. On the basis of the results of activity tests and microbial counts with wash-out cells, we identified two types of structured granules that were related to the influence of (gamma)(infLV). In one type of granules, hydrophilic acidogens surrounded a more hydrophobic methanogenic association. These granules were selected at a low (gamma)(infLV) provided that carbohydrates were available as substrates. The other type of granules was selected at a high (gamma)(infLV); hydrophobic cells (i.e., methanogens) were predominant throughout these granules. The granules which had acidogens as solid-phase emulsifiers around a methanogenic association appeared to allow more stable reactor performance. Decreasing the (gamma)(infLV) in the reactor by adding trace amounts of a surfactant also increased reactor stability. PMID:16535149

  14. Advanced development of a pressurized ash agglomerating fluidized-bed coal gasification system. Quarterly progress report, April 1-June 30, 1982

    SciTech Connect

    1982-10-21

    The overall objective of the Westinghouse coal gasification program is to demonstrate the viability of the Westinghouse pressurized, fluidized bed, gasification system for the production of medium-Btu fuel gas for syngas, electrical power generation, chemical feedstocks, or industrial fuels and to obtain performance and scaleup data for the process and hardware. Progress reports are presented for the following tasks: (1) operation and maintenance of the process development unit (PDU); (2) process analysis; (3) cold flow scaleup facility; (4) process and component engineering and design; and (5) laboratory support studies. Some of the highlights for this period are: TP-032-1, a single stage, oxygen-steam blown gasifier test was conducted in three operational phases from March 30, 1982 through May 2, 1982; TP-032-2 was conducted in two operational phases from May 20, 1982 through May 27, 1982; TP-032-1 and TP-032-2 successfully served as shakedown and demonstrations of the full cyclone cold wall; no visible deposits were found on the cold wall after processing highly fouling coals; samples of product gas produced during TP-032-1, were passed through four different scrubbing solutions and analyzed for 78 EPA primary organic pollutants, all of which were found to be below detection limits; TP-M004, a CO/sub 2/ tracer gas test, was initiated and completed; data analysis of test TP-M002-2 was completed and conclusions are summarized in this report; design, procurement and fabrication of the solids injection device were completed; laboratory studies involved gas-solids flow modeling and coal/ash behavior. 2 references, 11 figures, 39 tables.

  15. Sleep-Related Falling Out of Bed in Parkinson's Disease

    PubMed Central

    Shafazand, S.; Carvalho, D.Z.; Nahab, F.B.; Sengun, C.; Russell, A.; Moore, H.P.; Singer, C.

    2012-01-01

    Background and Purpose Sleep-related falling out of bed (SFOB), with its potential for significant injury, has not been a strong focus of investigation in Parkinson's disease (PD) to date. We describe the demographic and clinical characteristics of PD patients with and without SFOB. Methods We performed a retrospective analysis of 50 consecutive PD patients, who completed an REM sleep behavior disorder screening questionnaire (RBDSQ), questionnaires to assess for RBD clinical mimickers and questions about SFOB and resulting injuries. Determination of high risk for RBD was based on an RBDSQ score of 5 or greater. Results Thirteen patients reported history of SFOB (26%). Visual hallucinations, sleep-related injury, quetiapine and amantadine use were more common in those patients reporting SFOB. Twenty-two patients (44%) fulfilled criteria for high risk for RBD, 12 of which (55%) reported SFOB. Five patients reported injuries related to SFOB. SFOB patients had higher RBDSQ scores than non-SFOB patients (8.2±3.0 vs. 3.3±2.0, p<0.01). For every one unit increase in RBDSQ score, the likelihood of SFOB increased two-fold (OR 2.4, 95% CI 1.3-4.2, p<0.003). Conclusions SFOB may be a clinical marker of RBD in PD and should prompt confirmatory polysomnography and pharmacologic treatment to avoid imminent injury. Larger prospective studies are needed to identify risk factors for initial and recurrent SFOB in PD. PMID:22523513

  16. RELATING WEIGHT AND COUNT DISTRIBUTIONS OF STREAM BED GRAVEL

    EPA Science Inventory

    The size distribution of particles in a stream bed reflects the stream hydrology as well as its physical and chemical water quality characteristics. In environmental assessments, gravel distribution determines habitat quality for aquatic insects and stream suitability for spawnin...

  17. Agglomeration of Dust

    SciTech Connect

    Annaratone, B. M.; Arnas, C.; Elskens, Y.

    2008-09-07

    The agglomeration of the matter in plasma, from the atomic level up to millimetre size particles, is here considered. In general we identify a continuous growth, due to deposition, and two agglomeration steps, the first at the level of tens of nanometres and the second above the micron. The agglomeration of nano-particles is attributed to electrostatic forces in presence of charge polarity fluctuations. Here we present a model based on discrete currents. With increasing grain size the positive charge permanence decreases, tending to zero. This effect is only important in the range of nanometre for dust of highly dispersed size. When the inter-particle distance is of the order of the screening length another agglomeration mechanism dominates. It is based on attractive forces, shadow forces or dipole-dipole interaction, overcoming the electrostatic repulsion. In bright plasma radiation pressure also plays a role.

  18. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  19. Apparatus for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1987-05-12

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  20. Fluidized bed reactor apparatus and related gasification system

    SciTech Connect

    Fernandez, J.M.; Hoffert, F.D.; Marina, J.M.; Milligan, J.D.

    1982-11-16

    A process and pressurized, gasification reactor apparatus are claimed for converting combustible carbon containing materials such as coal char and other carbonaceous solids or carbonaceous solids/heavy oil combinations to an intermediate heating value fuel gas. The gasification reactor includes an insulated fluidized bed reactor chamber, an upper reactor housing for a freely suspended bayonet bundle type heat exchanger for (A) superheating incoming saturated steam and (B) cooling outgoing high temperature product gas, and a lower reactor housing structure which includes a freefloating, conically-shaped perforated plenum chamber. The superheated steam and oxygen are premixed with the plenum chamber before being pressure directed into the fluidized bed reactor chamber for mixture and combustion with the incoming combustible carbon containing materials such as coal char. After reaction of the superheated steam, oxygen and coal char in the fluidized bed reactor at temperatures ranging from 900/sup 0/ F to 1750/sup 0/ F, the product fuel gases and associated particulate matter are cooled by steam flowing through the bayonet heat exchanger, the steam being superheated by this exchange. After discharge from the heat exchanger, the fuel gas product containing particulate matter is pressure directed into a conventional cyclone separator for (A) separation of the desired product gases and (B) return of the particulate matter for further recycling in the reactor chamber. Undesirable ash clinkers are gravitationally and pressure directed out of the reactor chamber through a central ash withdrawal pipe.

  1. Agglomeration of ceramic powders

    NASA Technical Reports Server (NTRS)

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  2. Agglomeration of microparticles in complex plasmas

    SciTech Connect

    Du, Cheng-Ran; Thomas, Hubertus M.; Ivlev, Alexei V.; Konopka, Uwe; Morfill, Gregor E.

    2010-11-15

    Agglomeration of highly charged microparticles was observed and studied in complex plasma experiments carried out in a capacitively coupled rf discharge. The agglomeration was caused by strong waves triggered in a particle cloud by decreasing neutral gas pressure. Using a high-speed camera during this unstable regime, it was possible to resolve the motion of individual microparticles and to show that the relative velocities of some particles were sufficiently high to overcome the mutual Coulomb repulsion and hence to result in agglomeration. After stabilizing the cloud again through the increase of the pressure, we were able to observe the aggregates directly with a long-distance microscope. We show that the agglomeration rate deduced from our experiments is in good agreement with theoretical estimates. In addition, we briefly discuss the mechanisms that can provide binding of highly charged microparticles in a plasma.

  3. Near-wall particle velocity and concentration measurements in circulating fluidized beds in relation to heat transfer

    SciTech Connect

    Zevenhoven, R.; Kohlmann, J.; Laukkanen, T.; Tuominen, M.; Blomster, A.M.

    1999-07-01

    With the final goal of deriving correlations for suspension-to-wall heat transfer coefficients for circulating fluidized bed (CFB) reactors, video recordings on near-wall particle concentrations and velocities were made. Experiments were done at facilities at Foster Wheeler Energy Oy, Karhula, Finland, in pilot scale low and high temperature ({approximately}800 C) CFB reactors with rectangular cross-sections. The low temperature measurements gave information on near-wall particle concentrations, velocities sizes and their probability distributions, given a certain gas velocity and vertical position. In addition, a major effort went to high temperature measurements in a CFB combustor, using a water-cooled probe. Measuring basically the same things as in the cold facility, the objective there was to discriminate the relative importance of particle convective heat transfer (apart from obtaining any information at all from the hot CFB). Results are presented in the form of probability distributions for near-wall particle velocities and particle size for both CFBs. It was found that in the cold CFB, particle convective heat transfer accounts for up to almost 20% of the heat transfer. Comparing the cold and hot CFB results it was found that the contact time decreases with temperature. It is suggested that due to a different near-wall boundary layer at higher temperatures (and velocities), the particles moving downwards along the wall are more susceptible to horizontal re-entrainment forces. Since wall coverage data wasn't available (yet), heat transfer coefficients could not be calculated for the hot CFB data. In both CFBs the size of objects that were tracked was roughly the same as the input bed material particle size, meaning that no agglomerated particles were detected.

  4. Agglomeration rate and action forces between atomized particles of agglomerator and inhaled-particles from coal combustion.

    PubMed

    Wei, Feng; Zhang, Jun-ying; Zheng, Chu-guang

    2005-01-01

    In order to remove efficiently haled-particles emissions from coal combustions, a new way was used to put forward the process of agglomeration and the atomization was produced by the nozzle and then sprayed into the flue before precipitation devices of power station boiler in order to make inhaled-particles agglomerate into bigger particles, which can be easily removed but not change existing running conditions of boiler. According to this idea, a model is set up to study agglomeration rate and effect forces between fly ash inhaled-particles and atomized agglomerator particles. The developed agglomeration rate was expressed by relative particle number decreasing speed per unit volume. The result showed that viscosity force and flow resistance force give main influences on agglomeration effect of inhaled-particles, while springiness force and gravity have little effect on agglomeration effect of theirs. Factors influencing the agglomeration rate and effect forces are studied, including agglomerator concentration, agglomerator flux and agglomerator density, atomized-particles diameters and inhaled-particles diameter and so on. PMID:16295917

  5. Unstructured multigrid through agglomeration

    NASA Technical Reports Server (NTRS)

    Venkatakrishnan, V.; Mavriplis, D. J.; Berger, M. J.

    1993-01-01

    In this work the compressible Euler equations are solved using finite volume techniques on unstructured grids. The spatial discretization employs a central difference approximation augmented by dissipative terms. Temporal discretization is done using a multistage Runge-Kutta scheme. A multigrid technique is used to accelerate convergence to steady state. The coarse grids are derived directly from the given fine grid through agglomeration of the control volumes. This agglomeration is accomplished by using a greedy-type algorithm and is done in such a way that the load, which is proportional to the number of edges, goes down by nearly a factor of 4 when moving from a fine to a coarse grid. The agglomeration algorithm has been implemented and the grids have been tested in a multigrid code. An area-weighted restriction is applied when moving from fine to coarse grids while a trivial injection is used for prolongation. Across a range of geometries and flows, it is shown that the agglomeration multigrid scheme compares very favorably with an unstructured multigrid algorithm that makes use of independent coarse meshes, both in terms of convergence and elapsed times.

  6. Char binder for fluidized beds

    DOEpatents

    Borio, Richard W.; Accortt, Joseph I.

    1981-01-01

    An arrangement that utilizes agglomerating coal as a binder to bond coal fines and recycled char into an agglomerate mass that will have suitable retention time when introduced into a fluidized bed 14 for combustion. The simultaneous use of coal for a primary fuel and as a binder effects significant savings in the elimination of non-essential materials and processing steps.

  7. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-09-30

    Heap leaching is one of the methods being used to recover metal from low grade ore deposits. The main problem faced during heap leaching is the migration of fine grained particles through the heap, forming impermeable beds which result in poor solution flow. The poor solution flow leads to less contact between the leach solution and the ore, resulting in low recovery rates. Agglomeration of ore into coarse, porous masses prevents fine particles from migrating and clogging the spaces and channels between the larger ore particles. Currently, there is one facility in the United States which uses agglomeration. This operation agglomerates their ore using leach solution (raffinate), but is still experiencing undesirable metal recovery from the heaps due to agglomerate breakdown. The use of a binder, in addition to the leach solution, during agglomeration would help to produce stronger agglomerates that did not break down during processing. However, there are no known binders that will work satisfactorily in the acidic environment of a heap, at a reasonable cost. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. Increasing copper recovery in heap leaching by the use of binders and agglomeration would result in a significant decrease in the amount of energy consumed. Assuming that 70% of all the leaching heaps would convert to using agglomeration technology, as much as 1.64*10{sup 12} BTU per year would be able to be saved if a 25% increase in copper recovery was experienced, which is equivalent to saving approximately 18% of the energy currently being used in leaching heaps. For every week a leach cycle was decreased, a savings of as much as 1.23*10{sup 11} BTU per week would result. This project has identified several acid-resistant binders and agglomeration procedures. These binders and experimental procedures will be able to be used for use in improving the energy efficiency of

  8. Agglomeration and defluidization in FBC of biomass fuels -- Mechanisms and measures for prevention

    SciTech Connect

    Nordin, A.; Oehman, M.; Skrifvars, B.J.; Hupa, M.

    1996-12-31

    The use of biomass fuels in fluidized bed combustion (FBC) and gasification (FBG) is becoming more important because of the environmental benefits associated with these fuel and processes. However, severe bed agglomeration and defluidization have been reported due to the special ash forming constituents of some biomass fuels. Previous results have indicated that this could possibly be prevented by intelligent fuel mixing. In the present work the mechanisms of bed agglomeration using two different biomass fuels as well as the mechanism of the prevention of agglomeration by co-combustion with coal (50/50 %{sub w}) were studied. Several repeated combustion tests with the two biomass fuels, alone (Lucerne and olive flesh), all resulted in agglomeration and defluidization of the bed within less than 30 minutes. By controlled defluidization experiments the initial cohesion temperatures for the two fuels were determined to be as low as 670 C and 940 C, respectively. However, by fuel mixing the initial agglomeration temperature increased to 950 C and more than 1050 C, respectively. When co-combusted with coal during ten hour extended runs, no agglomeration was observed for either of the two fuel mixtures. The agglomeration temperatures were compared with results from a laboratory method, based on compression strength measurements of ash pellets, and results from chemical equilibrium calculations. Samples of bed materials, collected throughout the experimental runs, as well as the produced agglomerated beds, were analyzed using SEM EDS and X-ray diffraction. The results showed that loss of fluidization resulted from formation of molten phases coating the bed materials; a salt melt in the case of Lucerne and a silicate melt in the case of the olive fuel. By fuel mixing, the in-bed ash composition is altered, conferring higher melting temperatures, and thereby agglomeration and defluidization can be prevented.

  9. Test study of salty paper mill waste in a bubbling fluidized bed combustor

    SciTech Connect

    Wu, S.; Sellakumar, K.M.; Chelian, P.K.; Bleice, C.; Shaw, I.

    1999-07-01

    Foster Wheeler Pyropower Inc. has supplied a 73.7 kg/s bubbling fluidized bed boiler to MacMillan Bloedel's Powell River paper mill (now Pacifica Paper). The BFB boiler was designed to fire a fuel mixture of a mill effluent sludge and a hog fuel (bark) that is contaminated with seawater. Due to its very high alkali content and low ash content, the fuel is prone to cause problems such as agglomeration in the fluidized bed. Foster Wheeler and MacMillan Bloedel took a proactive approach to quantify likely problems and to identify solutions. A 200 hour-long test program was carried out at Foster Wheeler Development Corporation in Livingston, New Jersey with the Powell River feedstock. This paper provides the project background, an outline of the test facility, test matrix, fuel and bed material characteristics, followed by a test process overview. A summary of fuel alkali related agglomeration mechanism in fluidized bed is also included. The paper offers further observations on in-bed alkali accumulation as well as examinations of different types of bed material agglomerates found during the tests. A recommended boiler operating strategy for preventing agglomeration in the BFB boiler developed based on the test results is described. These recommendations have been successfully implemented during the start up of the boiler. The boiler has been in operation since November 1997. Boiler performance tests completed in April 1998 have demonstrated all guaranteed process conditions.

  10. The Relation of Variability in Sand Bed Topography to Sediment Transport

    NASA Astrophysics Data System (ADS)

    McElroy, B.; Mohrig, D.

    2006-05-01

    The estimation of bed material flux by comparing successive bathymetric surveys was developed under a deterministic light. However, an analogous stochastic treatment can be straightforwardly cast as an extension to the original bedload equation. Instead of an analysis that presumes a regular, geometrically defined bed topography, this accepts the natural noisiness of sandy systems and uses it to explicitly calculate sediment flux. Further, the sediment flux can be treated as the sum of 2 components, a translative flux and a deformative flux. The terminology for these two parts is explicitly related to their relative impacts on the bed. Because the translational part is exactly the same as the original, deterministic model, it estimates only the flux that advects the bed topography. In contrast, the deformational part encompasses all of the remaining bed material flux, the component that serves to change the shape or arrangement of the bed topography. Also, the deformative flux is constant of integration obtained a from manipulation of Exner's equation into average flux; this has been assumed null since the inception of the bedload equation. Analysis of data from the N. Loup River, Nebraska, show that the ratio of deformative to translative fluxes is constant over relevant timescales. The consequences of this are twofold. First, the amount of deformation can be directly calculated and the associated estimates of moved sediment volume are valid as the bed translates many characteristic lengths. In this case the Qtotal=1.8*Qtranslative. Second, it suggests that the fraction of deformation can be explicitly related to the characteristic length of beds. If true, it would greatly improve estimates of flux for all sandy systems and not just those for which extensive amounts of data have been collected.

  11. Selective oil agglomeration of lignite

    SciTech Connect

    Halime Abakay Temel; Volkan Bozkurt; Arun Kumar Majumder

    2009-01-15

    In this study, desulfurization and deashing of Adiyaman-Glbai lignite by the agglomeration method were studied. For this purpose, three groups of agglomeration experiments were made. The effects of solid concentration, bridging liquid type and dosage, pH, and screen size on the agglomeration after desliming were investigated in the first group of experiments. The effects of lake water and sea water (the Mediterranean Sea water, the Aegean Sea water, and the Black Sea water) on the agglomeration were investigated in the second group of experiments. The effects of different salts (NaCl, MgCl{sub 2}, and FeCl{sub 3}) on the agglomeration were investigated in the third group of experiments. Agglomeration results showed that the usage of sea waters and soda lake water in the agglomeration medium had a positive effect on the reduction of total sulfur content of agglomerates. In addition, the usage of NaCl, MgCl{sub 2}, and FeCl{sub 3} in the agglomeration medium had a positive effect on the ash content reduction of the agglomerates. 27 refs., 10 figs., 6 tabs.

  12. Spectral Element Agglomerate AMGe

    SciTech Connect

    Chartier, T; Falgout, R; Henson, V E; Jones, J E; Vassilevski, P S; Manteuffel, T A; McCormick, S F; Ruge, J W

    2005-05-20

    The purpose of this note is to describe an algorithm resulting from the uniting of two ideas introduced and applied elsewhere. For many problems, AMG has always been difficult due to complexities whose natures are difficult to discern from the entries of matrix A alone. Element-based interpolation has been shown to be an effective method for some of these problems, but it requires access to the element matrices on all levels. One way to obtain these has been to perform element agglomeration to form coarse elements, but in complicated situations defining the coarse degrees of freedom (dofs) is not easy. The spectral approach to coarse dof selection is very attractive due to its elegance and simplicity. The algorithm presented here combines the robustness of element interpolation, the ease of coarsening by element agglomeration, and the simplicity of defining coarse dofs through the spectral approach. As demonstrated in the numerical results, the method does yield a reasonable solver for the problems described. It can, however, be an expensive method due to the number and cost of the local, small dense linear algebra problems; making it a generally competitive method remains an area for further research.

  13. Apparatus and process for controlling fluidized beds

    DOEpatents

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

    An apparatus and process for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance.

  14. Post-quasistatic approximation as a test bed for numerical relativity

    SciTech Connect

    Barreto, W.

    2009-05-15

    It is shown that observers in the standard ADM 3+1 treatment of matter are the same as the observers used in the matter treatment of Bondi: they are comoving and local Minkowskian. Bondi's observers are the basis of the post-quasistatic approximation (PQSA) to study a contracting distribution of matter. This correspondence suggests the possibility of using the PQSA as a test bed for numerical relativity. The treatment of matter by the PQSA and its connection with the ADM 3+1 treatment are presented, for its practical use as a calibration tool and as a test bed for numerical relativistic hydrodynamic codes.

  15. Using a relative bed stability index to define a reference condition for assessing anthropogenic sedimentation

    EPA Science Inventory

    We developed an index of relative bed stability (LRBS) based on low flow survey data collected using the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) field methods to assess anthropogenic sedimentation in streams. LRBS is the log ...

  16. A roughness-corrected index of relative bed stability for regional stream surveys

    NASA Astrophysics Data System (ADS)

    Kaufmann, Philip R.; Faustini, John M.; Larsen, David P.; Shirazi, Mostafa A.

    2008-07-01

    Quantitative regional assessments of streambed sedimentation and its likely causes are hampered because field investigations typically lack the requisite sample size, measurements, or precision for sound geomorphic and statistical interpretation. We adapted an index of relative bed stability (RBS) for data calculated from a national stream survey field protocol to enable general evaluation of bed stability and anthropogenic sedimentation in synoptic ecological surveys. RBS is the ratio of bed surface geometric mean particle diameter ( Dgm) divided by estimated critical diameter ( Dcbf) at bankfull flow, based on a modified Shield's criterion for incipient motion. Application of RBS to adequately depict bed stability in complex natural streams, however, has been limited because typical calculations of RBS do not explicitly account for reductions in bed shear stress that result from channel form roughness. We modified the index (RBS *) to incorporate the reduction in bed shear stress available for sediment transport that results from the hydraulic resistance of large wood and longitudinal irregularities in channel dimensions ("form roughness"). Based on dimensional analysis, we derived an adjustment to bankfull shear stress by multiplying the bankfull hydraulic radius ( Rbf) by the one-third power of the ratio of particle-derived resistance to total hydraulic resistance ( Cp/ Ct) 1/3, where both resistances are empirically based calculations. We computed Cp using a Keulegan equation relating resistance to relative submergence of bed particles. We then derived an empirical equation to predict reach-scale hydraulic resistance Ct from thalweg mean depth, thalweg mean residual depth, and large wood volume based on field dye transit studies, in which total hydraulic resistance Ct was measured over a wide range of natural stream channel complexity, including manipulation of large wood volumes. We tested our estimates of Ct and RBS * by applying them to data from a summer

  17. Cross-bedding Related Anisotropy and its Role in the Orientation of Joints in an Aeolian Sandstone

    NASA Astrophysics Data System (ADS)

    Deng, S.; Cilona, A.; Mapeli, C.; Panfilau, A.; Aydin, A.; Prasad, M.

    2014-12-01

    Previous research revealed that the cross-bedding related anisotropy in aeolian sandstones affects the orientation of compaction bands, also known as anticracks. We hypothesize that cross-bedding should a have similar influence on the orientation of the joints within the same rock at the same location. To test this hypothesis, we investigated the relationship between the cross-beds and the cross-bed package confined joints in the Jurassic aeolian Aztec Sandstone cropping out in the Valley of Fire State Park, Nevada. The field data demonstrates that the cross-bed package confined joints occur at high-angle to bedding and trend roughly parallel to the dip direction of the cross-beds. This shows that the cross-bed orientation and the associated anisotropy also exert a strong control on the formation and orientation of the joints. In order to characterize the anisotropy due to cross-bedding in the Aztec Sandstone, we measured the P-wave velocities parallel and perpendicular to bedding from 11 samples in the laboratory using a bench-top ultrasonic assembly. The measured P-wave anisotropy is about 13% on average. Based on these results, a numerical model based on the generalized Hooke's law for anisotropic materials is analyzed assuming the cross-bedded sandstone to be transversely isotropic. Using this model, we tested various cross-bed orientations as well as different strain boundary conditions (uniaxial, axisymmetric and triaxial). It is possible to define a boundary condition under which the modeled results roughly match with the observed relationship between cross-bed package confined joints and cross-beds. These results have important implications for fluid flow through aeolian sandstones in reservoirs and aquifers.

  18. Particle Agglomeration in Bipolar Barb Agglomerator Under AC Electric Field

    NASA Astrophysics Data System (ADS)

    Huang, Chao; Ma, Xiuqin; Sun, Youshan; Wang, Meiyan; Zhang, Changping; Lou, Yueya

    2015-04-01

    The development of an efficient technology for removing fine particles in flue gas is essential as the haze is becoming more and more serious. To improve agglomeration effectiveness of fine particles, a dual zone electric agglomeration device consisting of a charging chamber and an agglomeration chamber with bipolar barb electrodes was developed. The bipolar barb electric agglomerator with a polar distance of 200 mm demonstrates good agglomeration effectiveness for particles with a size less than 8.0 μm under applied AC electric field. An optimal condition for achieving better agglomeration effectiveness was found to be as follows: flue gas flow velocity of 3.00 m/s, particle concentration of 2.00 g/m3, output voltage of 35 kV and length of the barb of 16 mm. In addition, 4.0-6.0 μm particles have the best effectiveness with the variation of particle volume occupancy of -3.2. supported by the Key Technology R&D Program of Hebei, China (No. 13211207D)

  19. Model for coal ash agglomeration based on two-particle dynamics

    SciTech Connect

    Moseley, J.L.; O'Brien, T.J.

    1986-01-01

    The agglomeration of coal and coal ash in fluidized-bed gasifiers (FBG's) is of great interest in coal conversion. However, only limited work has been done to develop analytical models in order to understand ash agglomeration in FBG's. This paper focuses on two-particle collision dynamics, which is then used to develop a criterion for the agglutination of the two particles. The main assumption of this mechanism is that the binding force can be modeled as ''piecewise'' conservative. This makes it possible to compute the maximum energy that can be dissipated by the system. Comparison of this quantity with the initial kinetic energy provides the agglutination criteria. A specific version of this model is obtained by making specific choices for the contact force and the binding force. An analytic formula for the critical velocity, the relative collision velocity below which agglutination takes place, is obtained for head-on collisions; a numerical technique is developed for collisions which are not head-on. A process change which increases the critical velocity increases the likelihood of agglutination of particles with random relative velocities. To examine the critical velocity as a function of temperature, the model requires correlations for the shear modulus and surface adhesiveness coefficient of the particles. Although these correlations are derived from limited experimental information, they lead to reasonable results and agreement with existing experimental data on agglomeration and defluidization. By considering the agglutination of particles of average size and temperature, a measure of the agglomeration tendency of a FBG can be obtained. Finally, the sensitivity of the model to system parameters is also investigated and an assessment of needed additional work is made. 35 refs., 12 figs.

  20. Coal Cleaning by Gas Agglomeration

    SciTech Connect

    Meiyu Shen; Royce Abbott; T. D. Wheelock

    1998-03-01

    The gas agglomeration method of coal cleaning was demonstrated with laboratory scale mixing equipment which made it possible to generate microscopic gas bubbles in aqueous suspensions of coal particles. A small amount of i-octane was introduced to enhance the hydrophobicity of the coal. Between 1.0 and 2.5 v/w% i-octane was sufficient based on coal weight. Coal agglomerates or aggregates were produced which were bound together by small gas bubbles.

  1. Recent Advances in Agglomerated Multigrid

    NASA Technical Reports Server (NTRS)

    Nishikawa, Hiroaki; Diskin, Boris; Thomas, James L.; Hammond, Dana P.

    2013-01-01

    We report recent advancements of the agglomerated multigrid methodology for complex flow simulations on fully unstructured grids. An agglomerated multigrid solver is applied to a wide range of test problems from simple two-dimensional geometries to realistic three- dimensional configurations. The solver is evaluated against a single-grid solver and, in some cases, against a structured-grid multigrid solver. Grid and solver issues are identified and overcome, leading to significant improvements over single-grid solvers.

  2. Microbial effects on colloidal agglomeration

    SciTech Connect

    Hersman, L.

    1995-11-01

    Colloidal particles are known to enhance the transport of radioactive metals through soil and rock systems. This study was performed to determine if a soil microorganism, isolated from the surface samples collected at Yucca Mountain, NV, could affect the colloidal properties of day particles. The agglomeration of a Wyoming bentonite clay in a sterile uninoculated microbial growth medium was compared to the agglomeration in the medium inoculated with a Pseudomonas sp. In a second experiment, microorganisms were cultured in the succinate medium for 50 h and removed by centrifugation. The agglomeration of the clay in this spent was compared to sterile uninoculated medium. In both experiments, the agglomeration of the clay was greater than that of the sterile, uninoculated control. Based on these results, which indicate that this microorganism enhanced the agglomeration of the bentonite clay, it is possible to say that in the presence of microorganisms colloidal movement through a rock matrix could be reduced because of an overall increase in the size of colloidal particle agglomerates. 32 refs.

  3. MTCI acoustic agglomeration particulate control

    SciTech Connect

    Chandran, R.R.; Mansour, M.N.; Scaroni, A.W.; Koopmann, G.H.; Loth, J.L.

    1994-10-01

    The overall objective of this project is to demonstrate pulse combination induced acoustic enhancement of coal ash agglomeration and sulfur capture at conditions typical of direct coal-fired turbines and PFBC hot gas cleanup. MTCI has developed an advanced compact pulse combustor island for direct coal-firing in combustion gas turbines. This combustor island comprises a coal-fired pulse combustor, a combined ash agglomeration and sulfur capture chamber (CAASCC), and a hot cyclone. In the MTCI proprietary approach, the pulse combustion-induced high intensity sound waves improve sulfur capture efficiency and ash agglomeration. The resulting agglomerates allow the use of commercial cyclones and achieve very high particulate collection efficiency. In the MTCI proprietary approach, sorbent particles are injected into a gas stream subjected to an intense acoustic field. The acoustic field serves to improve sulfur capture efficiency by enhancing both gas film and intra-particle mass transfer rates. In addition, the sorbent particles act as dynamic filter foci, providing a high density of stagnant agglomerating centers for trapping the finer entrained (in the oscillating flow field) fly ash fractions. A team has been formed with MTCI as the prime contractor and Penn State University and West Virginia University as subcontractors to MTCI. MTCI is focusing on hardware development and system demonstration, PSU is investigating and modeling acoustic agglomeration and sulfur capture, and WVU is studying aerovalve fluid dynamics. Results are presented from all three studies.

  4. Using a Relative Bed Stability Index to Define Reference Conditions for Assessing Anthropogenic Sedimentation

    NASA Astrophysics Data System (ADS)

    Faustini, J. M.; Kaufmann, P. R.; Larsen, D. P.

    2008-12-01

    We developed an index of relative bed stability (LRBS) based on low flow survey data collected using the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) field methods to assess anthropogenic sedimentation in streams. LRBS is the log of the ratio of bed surface geometric mean particle diameter (Dgm) to the estimated critical diameter (D*cbf) at bankfull flow, based on a modified Shield's criterion for incipient motion that explicitly accounts for reductions in bed shear stress resulting from channel form roughness due to pools and large wood. We hypothesized that human activities that augment sediment supply (particularly of fine sediments) without correspondingly increasing runoff or decreasing channel roughness should lead to reductions in LRBS as a result of textural fining of the streambed. Thus, LRBS values outside the range commonly observed in least- disturbed sites within a given region or class of streams could indicate potential human-caused sedimentation impacts. We tested the LRBS index using EMAP data from the Pacific Northwest Coast (PNW) and Mid- Atlantic regions of the United States. In both regions, LRBS was strongly inversely related to measures of anthropogenic disturbance intensity both at the watershed scale and in local riparian zone. In the PNW, streams draining relatively erodible sedimentary lithology (sandstone, siltstone) showed greater reductions in LRBS associated with disturbance than did those having more resistant volcanic lithology (basalt) with similar levels of basin and riparian disturbance. Correlations between Dgm and land disturbance were stronger than those observed between D*cbf and land disturbance in both regions, suggesting that land use has augmented sediment supplies and increased streambed fine sediments in the most disturbed streams. However, we also show evidence that some of the apparent reductions in LRBS in some streams (e.g., volcanic drainages in the PNW) may have

  5. Development of methods to predict agglomeration and disposition in FBCs

    SciTech Connect

    Mann, M.D.; Henderson, A.K.; Swanson, M.K.; Erickson, T.A.

    1995-11-01

    This 3-year, multiclient program is providing the information needed to determine the behavior of inorganic components in FBC units using advanced methods of analysis coupled with bench-scale combustion experiments. The major objectives of the program are as follows: (1) To develop further our advanced ash and deposit characterization techniques to quantify the effects of the liquid-phase components in terms of agglomerate formation and ash deposits, (2) To determine the mechanisms of inorganic transformations that lead to bed agglomeration and ash deposition in FBC systems, and (3) To develop a better means to predict the behavior of inorganic components as a function of coal composition, bed material characteristics, and combustion conditions.

  6. The relation of birthweight to histological appearances in vessels of the placental bed.

    PubMed

    McFadyen, I R; Price, A B; Geirsson, R T

    1986-05-01

    Biopsy of the placental bed was attempted at caesarean section in 109 patients: 77 consecutive and 32 selected because of the maternal or fetal condition. Forty-seven (44%) of these biopsies were from the placental bed and contained spiral arteries suitable for comment. Histological examination separated the patients into four groups: comprising 11 whose vessels showed normal physiological changes, 20 who showed inadequate physiological change, 12 with acute atherosis, and four with a mixed pattern. There was no relation between these changes and maternal age, parity, race or smoking habit, but no physiological change and atherosis were more common in association with maternal hypertension. Mean adjusted birthweight was greatest in those with physiological changes, less in those without physiological changes or the mixed pattern, and least in those with atherosis. The four patients in the mixed group did not have any unifying clinical characteristics. PMID:3707878

  7. Prostate cancer in relation to the use of electric blanket or heated water bed.

    PubMed

    Zhu, K; Weiss, N S; Stanford, J L; Daling, J R; Stergachis, A; McKnight, B; Brawer, M K; Levine, R S

    1999-01-01

    Using data from a case-control study conducted in Group Health Cooperative (GHC) of Puget Sound, we examined the relation between the use of electric blankets or heated water beds and the risk of prostate cancer. Cases were 175 prostate cancer patients ages 40-69 years. Controls were 258 male GHC members frequency matched to cases. The odds ratio (OR) for prostate cancer associated with the use of an electric blanket or heated water bed was 1.4 (95% confidence interval (CI) 0.9-2.2). The risk, however, did not tend to be higher with increasing months per year or years of use. This study did not provide clear evidence on the hypothesized association. PMID:9888286

  8. Crystal growth and agglomeration of calcium sulfite hemihydrate crystals

    SciTech Connect

    Tai, C.Y.; Chen, P.C.

    1995-04-01

    Flue gas desulfurization (FGD) processes are most commonly utilized to remove sulfur dioxide from stack gases of coal- or oil-fired plants. In the simple slurry technology, SO{sub 2} is absorbed by a slurry of lime/limestone to form calcium sulfite crystals of acicular habit and its strong agglomeration, requiring large clarifiers and filters to dewater the sludge to make an acceptable landfill. Crystal growth and agglomeration of calcium sulfite hemihydrate crystals from solution were studied by reacting Ca(OH){sub 2} with NaHSO{sub 3} in a pH-stat semibatch crystallizer. Single platelet crystals and agglomerates of platelet crystals were produced in the pH range from 5.80 to 6.80. The crystallization mechanism changed from primary nucleation to crystal growth in the progressive precipitation. Using the titration curves, the growth rate was calculated from the titration rate at the final stage of operation. The crystal growth rates of calcium sulfate hemihydrate crystals were found to obey the parabolic rate law in the low supersaturation range. Another point to be noted is that the precipitates of calcium sulfite hemihydrate in agitated suspensions have a tendency to form agglomerates. It was found that the degree of agglomeration is a weak function of relative supersaturation and magma density, while the pH value is a key factor that affects the degree of agglomeration. Addition of EDTA also has an effect on the agglomeration of calcium sulfite hemihydrates.

  9. COAL CLEANING BY GAS AGGLOMERATION

    SciTech Connect

    T.D. Wheelock

    1999-03-01

    The technical feasibility of a gas agglomeration method for cleaning coal was demonstrated by means of bench-scale tests conducted with a mixing system which enabled the treatment of ultra-fine coal particles with a colloidal suspension of microscopic gas bubbles in water. A suitable suspension of microbubbles was prepared by first saturating water with air or carbon dioxide under pressure then reducing the pressure to release the dissolved gas. The formation of microbubbles was facilitated by agitation and a small amount of i-octane. When the suspension of microbubbles and coal particles was mixed, agglomeration was rapid and small spherical agglomerates were produced. Since the agglomerates floated, they were separated from the nonfloating tailings in a settling chamber. By employing this process in numerous agglomeration tests of moderately hydrophobic coals with 26 wt.% ash, it was shown that the ash content would be reduced to 6--7 wt.% while achieving a coal recovery of 75 to 85% on a dry, ash-free basis. This was accomplished by employing a solids concentration of 3 to 5 w/w%, an air saturation pressure of 136 to 205 kPa (5 to 15 psig), and an i-octane concentration of 1.0 v/w% based on the weight of coal.

  10. Acoustic agglomeration methods and apparatus

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B. (Inventor)

    1984-01-01

    Methods are described for using acoustic energy to agglomerate fine particles on the order of one micron diameter that are suspended in gas, to provide agglomerates large enough for efficient removal by other techniques. The gas with suspended particles, is passed through the length of a chamber while acoustic energy at a resonant chamber mode is applied to set up one or more acoustic standing wave patterns that vibrate the suspended particles to bring them together so they agglomerate. Several widely different frequencies can be applied to efficiently vibrate particles of widely differing sizes. The standing wave pattern can be applied along directions transversed to the flow of the gas. The particles can be made to move in circles by applying acoustic energy in perpendicular directions with the energy in both directions being of the same wavelength but 90 deg out of phase.

  11. Compression behavior of porous dust agglomerates

    NASA Astrophysics Data System (ADS)

    Seizinger, A.; Speith, R.; Kley, W.

    2012-05-01

    Context. The early planetesimal growth proceeds through a sequence of sticking collisions of dust agglomerates. Very uncertain is still the relative velocity regime in which growth rather than destruction can take place. The outcome of a collision depends on the bulk properties of the porous dust agglomerates. Aims: Continuum models of dust agglomerates require a set of material parameters that are often difficult to obtain from laboratory experiments. Here, we aim at determining those parameters from ab initio molecular dynamics simulations. Our goal is to improve on the existing model that describe the interaction of individual monomers. Methods: We use a molecular dynamics approach featuring a detailed micro-physical model of the interaction of spherical grains. The model includes normal forces, rolling, twisting and sliding between the dust grains. We present a new treatment of wall-particle interaction that allows us to perform customized simulations that directly correspond to laboratory experiments. Results: We find that the existing interaction model by Dominik & Tielens leads to a too soft compressive strength behavior for uni- and omni-directional compression. Upon making the rolling and sliding coefficients stiffer we find excellent agreement in both cases. Additionally, we find that the compressive strength curve depends on the velocity with which the sample is compressed. Conclusions: The modified interaction strengths between two individual dust grains will lead to a different behavior of the whole dust agglomerate. This will influences the sticking probabilities and hence the growth of planetesimals. The new parameter set might possibly lead to an enhanced sticking as more energy can be stored in the system before breakup.

  12. Air agglomeration of hydrophobic particles

    SciTech Connect

    Drzymala, J.; Wheelock, T.D.

    1995-12-31

    The agglomeration of hydrophobic particles in an aqueous suspension was accomplished by introducing small amounts of air into the suspension while it was agitated vigorously. The extent of aggregation was proportional both to the air to solids ratio and to the hydrophobicity of the solids. For a given air/solids ratio, the extent of aggregation of different materials increased in the following order: graphite, gilsonite, coal coated with heptane, and Teflon. The structure of agglomerates produced from coarse Teflon particles differed noticeably from the structure of bubble-particle aggregates produced from smaller, less hydrophobic particles.

  13. Low-rank coal oil agglomeration product and process

    DOEpatents

    Knudson, C.L.; Timpe, R.C.; Potas, T.A.; DeWall, R.A.; Musich, M.A.

    1992-11-10

    A selectively-sized, raw, low-rank coal is processed to produce a low ash and relative water-free agglomerate with an enhanced heating value and a hardness sufficient to produce a non-degradable, shippable fuel. The low-rank coal is treated, under high shear conditions, in the first stage to cause ash reduction and subsequent surface modification which is necessary to facilitate agglomerate formation. In the second stage the treated low-rank coal is contacted with bridging and binding oils under low shear conditions to produce agglomerates of selected size. The bridging and binding oils may be coal or petroleum derived. The process incorporates a thermal deoiling step whereby the bridging oil may be completely or partially recovered from the agglomerate; whereas, partial recovery of the bridging oil functions to leave as an agglomerate binder, the heavy constituents of the bridging oil. The recovered oil is suitable for recycling to the agglomeration step or can serve as a value-added product.

  14. Low-rank coal oil agglomeration product and process

    DOEpatents

    Knudson, Curtis L.; Timpe, Ronald C.; Potas, Todd A.; DeWall, Raymond A.; Musich, Mark A.

    1992-01-01

    A selectively-sized, raw, low-rank coal is processed to produce a low ash and relative water-free agglomerate with an enhanced heating value and a hardness sufficient to produce a non-decrepitating, shippable fuel. The low-rank coal is treated, under high shear conditions, in the first stage to cause ash reduction and subsequent surface modification which is necessary to facilitate agglomerate formation. In the second stage the treated low-rank coal is contacted with bridging and binding oils under low shear conditions to produce agglomerates of selected size. The bridging and binding oils may be coal or petroleum derived. The process incorporates a thermal deoiling step whereby the bridging oil may be completely or partially recovered from the agglomerate; whereas, partial recovery of the bridging oil functions to leave as an agglomerate binder, the heavy constituents of the bridging oil. The recovered oil is suitable for recycling to the agglomeration step or can serve as a value-added product.

  15. Low-rank coal oil agglomeration

    DOEpatents

    Knudson, Curtis L.; Timpe, Ronald C.

    1991-01-01

    A low-rank coal oil agglomeration process. High mineral content, a high ash content subbituminous coals are effectively agglomerated with a bridging oil which is partially water soluble and capable of entering the pore structure, and usually coal derived.

  16. Tensiomygraphic Measurement of Atrophy Related Processes During Bed Rest and Recovery

    NASA Astrophysics Data System (ADS)

    Simunic, B. ostjan; Degens, Hans; Rittweger, Jorn; Narici, Marcco; Pisot, Venceslav; Mekjavic, Igor B.; Pisot, Rado

    2013-02-01

    Tensiomyographic (TMG) parameters were recently proposed for a non-invasive estimation of MHC distribution in human vastus lateralis muscle. However, TMG potential is even higher, offers additional insight into the skeletal muscle physiology, especially in the field of atrophy and hypertrophy. The purpose of this study is in developing time dynamics of TMG-measured contraction time (Tc) and maximal response amplitude (Dm), together with muscle belly thickness, measure thoroughly during 35-day bed rest and followed in 30-day recovery (N = 10 males; age 24.3 ± 2.6 years). Measurements were performed in two postural muscles (vastus medialis and lateralis) and one non-postural muscle (biceps femoris). During bed rest period we found different dynamics of muscle thickness decrease and Dm increase. Tc was unchanged in postural muscles, but in non-postural muscle increased significantly and stayed as such even at the end of recovery. We could conclude that TMG related parameters are more sensitive in measuring muscle atrophic and hypertrophic processes than biomedical imaging technique. However, a mechanism that regulates Dm still needs to be identified.

  17. Adapting agglomeration techniques to today's needs

    SciTech Connect

    Brown, D.C.

    1984-07-01

    New industries and economic trends have created new problems and opportunities for which applications of agglomeration have been developed. These applications are presented and discussed briefly. The areas include sintering of finely divided ores, briquetting feed stocks, agglomerate forms for air pollution control, hazardous waste immobilization, briquetting solid fuels for energy conservation, manufacturing synfuel charges, biomass densification, and agglomerate forms for metallurgical coke.

  18. Microstickies agglomeration by electric field.

    PubMed

    Du, Xiaotang Tony; Hsieh, Jeffery S

    2016-01-01

    Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied. PMID:27332828

  19. Coal beneficiation by gas agglomeration

    DOEpatents

    Wheelock, Thomas D.; Meiyu, Shen

    2003-10-14

    Coal beneficiation is achieved by suspending coal fines in a colloidal suspension of microscopic gas bubbles in water under atmospheric conditions to form small agglomerates of the fines adhered by the gas bubbles. The agglomerates are separated, recovered and resuspended in water. Thereafter, the pressure on the suspension is increased above atmospheric to deagglomerate, since the gas bubbles are then re-dissolved in the water. During the deagglomeration step, the mineral matter is dispersed, and when the pressure is released, the coal portion of the deagglomerated gas-saturated water mixture reagglomerates, with the small bubbles now coming out of the solution. The reagglomerate can then be separated to provide purified coal fines without the mineral matter.

  20. Centrifugal air-assisted melt agglomeration for fast-release "granulet" design.

    PubMed

    Wong, Tin Wui; Musa, Nafisah

    2012-07-01

    Conventional melt pelletization and granulation processes produce round and dense, and irregularly shaped but porous agglomerates respectively. This study aimed to design centrifugal air-assisted melt agglomeration technology for manufacture of spherical and yet porous "granulets" for ease of downstream manufacturing and enhancing drug release. A bladeless agglomerator, which utilized shear-free air stream to mass the powder mixture of lactose filler, polyethylene glycol binder and poorly water-soluble tolbutamide drug into "granulets", was developed. The inclination angle and number of vane, air-impermeable surface area of air guide, processing temperature, binder content and molecular weight were investigated with reference to "granulet" size, shape, texture and drug release properties. Unlike fluid-bed melt agglomeration with vertical processing air flow, the air stream in the present technology moved centrifugally to roll the processing mass into spherical but porous "granulets" with a drug release propensity higher than physical powder mixture, unprocessed drug and dense pellets prepared using high shear mixer. The fast-release attribute of "granulets" was ascribed to porous matrix formed with a high level of polyethylene glycol as solubilizer. The agglomeration and drug release outcomes of centrifugal air-assisted technology are unmet by the existing high shear and fluid-bed melt agglomeration techniques. PMID:22531845

  1. Age-related differences in plasma BDNF levels after prolonged bed rest.

    PubMed

    Soavi, Cecilia; Marušič, Uroš; Sanz, Juana Maria; Morieri, Mario Luca; Dalla Nora, Edoardo; Šimunič, Bostjan; Pišot, Rado; Zuliani, Giovanni; Passaro, Angelina

    2016-05-15

    Brain-derived neurotrophic factor (BDNF) is a member of the family of neurotrophins and has been implicated in brain resistance to insults. Murine studies have demonstrated increased hippocampal concentration after acute immobilization and decreased concentration after chronic immobilization. In humans, chronic stress and sedentary lifestyle result in decreased plasma BDNF levels, but there no data exist regarding acute immobilization. The aim of our study was to evaluate age-related responses [comparing 7 younger subjects (age 23 ± 3 yr) and 8 older subjects (age 60 ± 4 yr)] of plasma BDNF before (baseline data collection, BDC) and after 14 days (BR14) of horizontal bed rest (BR). At BDC, BDNF levels were not different between the two groups (P = 0.101), although at BR14, BDNF levels were higher in older subjects (62.02 ± 18.31) than in younger subjects (34.36 ± 15.24 pg/ml) (P = 0.002). A general linear model for repeated measures showed a significant effect of BR on BDNF (P = 0.002). The BDC BDNF levels correlated with fat-free mass in both populations (ALL) (R = 0.628, P = 0.012), (older, R = 0.753, P = 0.031; younger, R = 0.772, P = 0.042), and with total cholesterol in ALL (R = 0.647, P = 0.009) and older study subjects (R = 0.805, P = 0.016). At BR14, BDNF correlated with total cholesterol (R = 0.579, P = 0.024) and age (R = 0.647, P = 0.009) in ALL. With an increase in age, the brain could become naturally less resistant to acute stressors, including the detrimental effects of prolonged bed rest, and thus the increase in BDNF in the older study group might reflect a protective overshooting of the brain to counteract the negative effects in such conditions. PMID:26940658

  2. Mechanisms for selective agglomeration of coals

    SciTech Connect

    Wheelock, T.D.; Drzymala, J.; Allen, R.W.; Hu, Y.-C.; Tyson, D.; Xiaoping, Qiu; Lessa, A.

    1989-05-01

    Work continued on the basic mechanisms which underlie various processes for beneficiating aqueous suspensions of coal by selective agglomeration with oil. A new method was demonstrated for characterizing the agglomerability of coal suspensions. This method utilizes a photometric dispersion analyzer to monitor changes in the turbidity of a particle suspension as increasing amounts of oil are added to the suspension in a batch agglomeration test. Agglomeration of the particles leads to a marked decrease in the turbidity of the suspension. Another experimental technique was also demonstrated for characterizing oil agglomeration. This technique involves measuring the rate of growth of agglomerates in a continuous flow system operating under stead-state conditions. The data are analyzed by means of a population balance. The results of a preliminary set of experiments in which Indiana V seam coal was agglomerated with tetralin seemed to fit a particular growth model very well. Equipment was also constructed for studying the kinetics of agglomeration in a batch process. While earlier work showed that quebracho (a commercially available dispersant) is a strong agglomeration depressant for pyrite, recent experiments with mixtures of Upper Freeport coal and mineral pyrite showed that quebracho does not appear to be sufficiently selective. Further consideration was given to the separation of mixtures of coal and pyrite agglomeration with heptane. 2 refs., 17 figs., 1 tab.

  3. Ice slurry cooling research: Storage tank ice agglomeration and extraction

    SciTech Connect

    Kasza, K.; Hayashi, Kanetoshi

    1999-08-01

    A new facility has been built to conduct research and development on important issues related to implementing ice slurry cooling technology. Ongoing studies are generating important information on the factors that influence ice particle agglomeration in ice slurry storage tanks. The studies are also addressing the development of methods to minimize and monitor agglomeration and improve the efficiency and controllability of tank extraction of slurry for distribution to cooling loads. These engineering issues impede the utilization of the ice slurry cooling concept that has been under development by various groups.

  4. Anthropogenic sedimentation in Pacific Northwest streams inferred from Aquatic Habitat Survey datausing a relative bed stability index

    EPA Science Inventory

    We evaluated anthropogenic sedimentation in U.S. Pacific Northwest coastal streams using an index of relative bed stability (LRBS*) based on low flow survey data collected using the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) fiel...

  5. Serum sclerostin and DKK1 in relation to exercise against bone loss in experimental bed rest.

    PubMed

    Belavý, Daniel L; Baecker, Natalie; Armbrecht, Gabriele; Beller, Gisela; Buehlmeier, Judith; Frings-Meuthen, Petra; Rittweger, Jörn; Roth, Heinz J; Heer, Martina; Felsenberg, Dieter

    2016-05-01

    The impact of effective exercise against bone loss during experimental bed rest appears to be associated with increases in bone formation rather than reductions of bone resorption. Sclerostin and dickkopf-1 are important inhibitors of osteoblast activity. We hypothesized that exercise in bed rest would prevent increases in sclerostin and dickkopf-1. Twenty-four male subjects performed resistive vibration exercise (RVE; n = 7), resistive exercise only (RE; n = 8), or no exercise (control n = 9) during 60 days of bed rest (2nd Berlin BedRest Study). We measured serum levels of BAP, CTX-I, iPTH, calcium, sclerostin, and dickkopf-1 at 16 time-points during and up to 1 year after bed rest. In inactive control, after an initial increase in both BAP and CTX-I, sclerostin increased. BAP then returned to baseline levels, and CTX-I continued to increase. In RVE and RE, BAP increased more than control in bed rest (p ≤ 0.029). Increases of CTX-I in RE and RVE did not differ significantly to inactive control. RE may have attenuated increases in sclerostin and dickkopf-1, but this was not statistically significant. In RVE there was no evidence for any impact on sclerostin and dickkopf-1 changes. Long-term recovery of bone was also measured and 6-24 months after bed rest, and proximal femur bone mineral content was still greater in RVE than control (p = 0.01). The results, while showing that exercise against bone loss in experimental bed rest results in greater bone formation, could not provide evidence that exercise impeded the rise in serum sclerostin and dickkopf-1 levels. PMID:26056021

  6. Development of a gas-promoted oil agglomeration process. Quarterly technical progress report, July 1, 1995--September 30, 1995

    SciTech Connect

    Wheelock, T.D.

    1995-12-31

    The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal advanced in three major research areas. One area of research resulted in the development of a method for measuring the rate of agglomeration of dilute particle suspensions and using the method to relate the rate of agglomeration of coal particles to various key parameters. A second area of research led to the development of a method for monitoring a batch agglomeration process by measuring changes in agitator torque. With this method it was possible to show that the agglomeration of a concentrated coal particle suspension is triggered by the introduction of a small amount of gas. The method was also used in conjunction with optical microscopy to study the mechanism of agglomeration. A third area of research led to the discovery that highly hydrophobic particles in an aqueous suspension can be agglomerated by air alone.

  7. Agglomerating combustor-gasifier method and apparatus for coal gasification

    DOEpatents

    Chen, Joseph L. P.; Archer, David H.

    1976-09-21

    A method and apparatus for gasifying coal wherein the gasification takes place in a spout fluid bed at a pressure of about 10 to 30 atmospheres and a temperature of about 1800.degree. to 2200.degree.F and wherein the configuration of the apparatus and the manner of introduction of gases for combustion and fluidization is such that agglomerated ash can be withdrawn from the bottom of the apparatus and gas containing very low dust loading is produced. The gasification reaction is self-sustaining through the burning of a stoichiometric amount of coal with air in the lower part of the apparatus to form the spout within the fluid bed. The method and apparatus are particularly suitable for gasifying coarse coal particles.

  8. Significant bed elevation changes related to Gulf Stream dynamics on the South Carolina continental shelf

    USGS Publications Warehouse

    Gelfenbaum, G.; Noble, M.

    1993-01-01

    Photographs of the seabed taken from an instrumented bottom tripod located approximately 100 km east of Charleston, South Carolina, reveal bed elevation changes of over 20 cm between July and November 1978. The tripod was in 85 m of water and was equipped with two current meters at 38.7 and 100 cm from the bed, a pressure sensor, a transmissometer, which fouled early during the deployment, a temperature sensor and a camera. The sediment under the tripod was composed of poorly sorted sand, some shell debris and numerous small biological tubes. Bed roughness varied throughout the deployment from biologically-produced mounds (2-5 cm high and 5-20 cm diameter) to streaks to a smooth bed, depending upon the frequency and magnitude of the sediment transporting events. Even though these events were common, especially during the later part of the deployment, the bed was rarely rippled, and there was no evidence of large bedforms such as dunes or sand waves migrating through the field of view of the camera. Photographs did clearly show, however, a gradual net deposition of the bed of nearly 20 cm, followed by erosion of approximately 5 cm. The flow field near the bed was dominated by sub-tidal period currents. Hourly-averaged currents at 100 cm from the bed typically varied between 10 and 30 cm s-1 and occasionally were as high as 60 cm s-1. The large flow events were predominantly toward the southwest along the shelf in the opposite direction of the northeast flowing Gulf Stream. The cross-shore component of the flow near the bed was predominantly directed offshore due to a local topographic steering effect. Current, temperature and satellite data suggest that the largest flow events were associated with the advection of Gulf Stream filaments past the tripod. Erosion events, as seen from the photographs, were highly correlated with the passage of these Gulf Stream filaments past the tripod. Gradual deposition of sediment, which occurred during the first half of the

  9. Soot agglomeration in isolated, free droplet combustion

    NASA Technical Reports Server (NTRS)

    Choi, M. Y.; Dryer, F. L.; Green, G. J.; Sangiovanni, J. J.

    1993-01-01

    Under the conditions of an isolated, free droplet experiment, hollow, carbonaceous structures, called soot spheres, were observed to form during the atmospheric pressure, low Reynolds number combustion of 1-methylnaphthalene. These structures which are agglomerates composed of smaller spheroidal units result from both thermophoretic effects induced by the envelope flame surrounding each drop and aerodynamic effects caused by changes in the relative gas/drop velocities. A chemically reacting flow model was used to analyze the process of sootshell formation during microgravity droplet combustion. The time-dependent temperature and gas property field surrounding the droplet was determined, and the soot cloud location for microgravity combustion of n-heptane droplets was predicted. Experiments showed that the sooting propensity of n-alkane fuel droplets can be varied through diluent substitution, oxygen-index variations, and ambient pressure reductions.

  10. Low-rank coal oil agglomeration

    DOEpatents

    Knudson, C.L.; Timpe, R.C.

    1991-07-16

    A low-rank coal oil agglomeration process is described. High mineral content, a high ash content subbituminous coals are effectively agglomerated with a bridging oil which is partially water soluble and capable of entering the pore structure, and is usually coal-derived.

  11. Engineering development of selective agglomeration. Final report

    SciTech Connect

    Not Available

    1993-04-01

    This report presents the findings of the project entitled ``Engineering Development of Selective Agglomeration.`` The purpose is to develop selective agglomeration technology to a commercially acceptable level by 1993. Engineering development included bench-scale process development, component development adaptation or modification of existing unit operations, proof-of-concept (POC) module design, fabrication, testing, data evaluation, and conceptual design of a commercial facility. The information obtained during POC operation resulted in a technical and economic design base sufficient to support construction and operation of a commercial plant. Throughout this project performance targets for the engineering development of selective agglomeration process were to achieve 85% or greater Btu recovery at 85% or greater pyritic sulfur rejection (PSR). Additional objectives included producing a final clean-coal product with an ash content of 6% or less which is suitable for conventional coal handling systems. The selective agglomeration process, as applied to coal cleaning, is based on differences in the surface chemistry of coal and its associated impurities. Coal particles are hydrophobic (i.e., repel water) while the majority of its impurities are hydrophilic (i.e., stabilized in water). During selective agglomeration, a liquid (the agglomerant) that is immiscible with water is introduced into a coal-water slurry and agitated to disperse it in the slurry, thereby allowing it to come into contact with all particles in the slurry. The coal particles, due to their hydrophobic nature, are attracted to the agglomerant phase. The hydrophilic mineral impurities remain in the water phase. Continued agitation of the agglomerant-coated coal particles causes them to coalesce to form agglomerates. Once the agglomerates are formed, they are separated from the mineral matter-bearing aqueous phase by subsequent processing steps.

  12. Divestment of Beds and Related Ambulatory Services to Other Communities While Maintaining a Patient- and Family-Centred Approach.

    PubMed

    Corring, Deborah J; Gibson, Deborah; MustinPowell, Jill

    2016-01-01

    Individuals living with serious mental illness who require acute and/or tertiary mental healthcare services represent one of the most complex patient groups in the healthcare service delivery system. Provincial mental health policy has been committed to providing services closer to home and in the community rather than an institution wherever possible for some time. This paper articulates the strategies used by one organization to ensure the successful transfer of beds and related ambulatory services to four separate communities. In addition a case study is also provided to describe in more detail the complex changes that took place in order to accomplish the divestments of beds and related ambulatory services to one of the partner hospitals. PMID:26854542

  13. No sex-related differences in mortality in bed bugs (Hemiptera: Cimicidae) exposed to deltamethrin, and surviving bed bugs can recover.

    PubMed

    Feldlaufer, Mark F; Ulrich, Kevin R; Kramer, Matthew

    2013-04-01

    Exposure of a pyrethroid-susceptible strain of bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae) to varying concentrations of deltamethrin for 24 h indicated no significant difference in mortality between males, females, and nymphs at 24 nor at 168 h postexposure when bed bugs were removed to untreated surfaces at 24 h. In addition, many bed bugs classified as morbid or moribund at 24 h and removed to untreated surfaces at this time, recovered by 336 h (2 wk) and were capable of feeding when given the opportunity. Adult female bed bugs that survived were able to lay eggs and the resulting nymphs blood-fed. By contrast, all bed bugs classified as morbid or moribund at 24 h that remained on deltamethrin-treated surfaces for 336 h either died or were still classified as morbid or moribund at the end of this time. No bed bugs classified as morbid or moribund blood-fed when given the opportunity at 2 wk, regardless of whether they remained on the treated surfaces or were removed to untreated surfaces. A power analysis demonstrated we would have detected even moderate differences in mortality between males and females, had differences existed. Therefore, using males exclusively in efficacy assays is a suitable strategy to preserve females for laboratory colony purposes. Results also indicated there is little reason to assess efficacy beyond 1 wk, even when bed bugs are exposed for only 24 h. PMID:23786091

  14. Modeling of particle agglomeration in nanofluids

    NASA Astrophysics Data System (ADS)

    Krishna, K. Hari; Neti, S.; Oztekin, A.; Mohapatra, S.

    2015-03-01

    Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed.

  15. Effect of particle agglomeration in nanotoxicology.

    PubMed

    Bruinink, Arie; Wang, Jing; Wick, Peter

    2015-05-01

    The emission of engineered nanoparticles (ENPs) into the environment in increasing quantity and variety raises a general concern regarding potential effects on human health. Compared with soluble substances, ENPs exhibit additional dimensions of complexity, that is, they exist not only in various sizes, shapes and chemical compositions but also in different degrees of agglomeration. The effect of the latter is the topic of this review in which we explore and discuss the role of agglomeration on toxicity, including the fate of nanomaterials after their release and the biological effects they may induce. In-depth investigations of the effect of ENP agglomeration on human health are still rare, but it may be stated that outside the body ENP agglomeration greatly reduces human exposure. After uptake, agglomeration of ENPs reduces translocation across primary barriers such as lungs, skin or the gastrointestinal tract, preventing exposure of "secondary" organs. In analogy, also cellular ENP uptake and intracellular distribution are affected by agglomeration. However, agglomeration may represent a risk factor if it occurs after translocation across the primary barriers, and ENPs are able to accumulate within the tissue and thus reduce clearance efficiency. PMID:25618546

  16. Modeling of particle agglomeration in nanofluids

    SciTech Connect

    Krishna, K. Hari; Neti, S.; Oztekin, A.; Mohapatra, S.

    2015-03-07

    Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed.

  17. Modeling of Particle Agglomeration in Nanofluids

    NASA Astrophysics Data System (ADS)

    Kanagala, Hari Krishna

    Nanofluids are colloidal dispersions of nano sized particles (<100nm in diameter) in dispersion mediums. They are of great interest in industrial applications as heat transfer fluids owing to their enhanced thermal conductivities. Stability of nanofluids is a major problem hindering their industrial application. Agglomeration and then sedimentation are some reasons, which drastically decrease the shelf life of these nanofluids. Current research addresses the agglomeration effect and how it can affect the shelf life of a nanofluid. The reasons for agglomeration in nanofluids are attributable to the interparticle interactions which are quantified by the various theories. By altering the governing properties like volume fraction, pH and electrolyte concentration different nanofluids with instant agglomeration, slow agglomeration and no agglomeration can be produced. A numerical model is created based on the discretized population balance equations which analyses the particle size distribution at different times. Agglomeration effects have been analyzed for alumina nanoparticles with average particle size of 150nm dispersed in de-ionized water. As the pH was moved towards the isoelectric point of alumina nanofluids, the particle size distribution became broader and moved to bigger sizes rapidly with time. Particle size distributions became broader and moved to bigger sizes more quickly with time with increase in the electrolyte concentration. The two effects together can be used to create different temporal trends in the particle size distributions. Faster agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces which is due to decrease in the induced charge and the double layer thickness around the particle. Bigger particle clusters show lesser agglomeration due to reaching the equilibrium size. The procedures and processes described in this work can be used to generate more stable nanofluids.

  18. Percolative fragmentation and spontaneous agglomeration

    SciTech Connect

    Hurt, R.; Davis, K.

    1999-03-01

    Captive particle imaging experiments were performed on over 200 coal and char particles in the pulverized size range from four coals of various rank at oxygen concentration from 3--19 mol% and at gas temperatures of about 1250 K. Despite wide variations in single-particle behavior, the data set reveals two clear trends that provide new information on the nature of char combustion. First, the low-rank coal chars are observed to maintain their high reactivity through the late stages of combustion, thus avoiding the near-extinction events and long burnout tails observed for bituminous coal chars. Secondly, percolative fragmentation in the late stages of combustion is a rare event under these conditions. Some particles reach a percolation threshold rate in combustion, but typically undergo spontaneous agglomeration rather than liberation of the incipient fragments. It is concluded that percolative fragmentation behavior in the pulverized size range is determined not only by solid-phase connectivity, but also by a real competition between disruptive and cohesive forces present at the time of formation of the colloidal-sized incipient fragments.

  19. Agglomeration in Stripper Ash Coolers and Its Possible Remedial Solutions: a Case Study

    NASA Astrophysics Data System (ADS)

    Singh, Ravi Inder

    2016-04-01

    The bottom ash of circulating fluidized bed (CFB) boiler contains large amounts of physical heat. When low quality coals are used in these types of boilers, the ash content is normally more than 40 % and the physical heat loss is approximately 3 % if the bottom ash is discharged without cooling. Bottom ash cooler (BAC) is often used to treat the high temperature bottom ash to reclaim heat, and to facilitate the easily handling and transportation of ash. The CFB boiler at BLA Power, Newari, MP (India) is facing problems of clinker formation in strip ash coolers of plant since the installation of unit. These clinkers are basically agglomerates, which leads to defluidization of stripper ash cooler (BAC) units. There are two strip ash coolers in unit. Each strip ash cooler is capable of working independently. The proper functioning of both strip coolers is very important as it is going to increase the combustion efficiency of boiler by stripping of fine unburnt coal particles from ash, which are injected into the furnace. In this paper causes, characterization of agglomerates, thermo gravimetric analysis of fuel used, particular size distribution of coal and sand and possible remedial solution to overcome these agglomerates in strip ash coolers has also been presented. High temperature in compact separators, non uniform supply of coal and not removing small agglomerates from stripper ash cooler are among main causes of agglomeration in stripper ash cooler. Control of compact separator temperature, replacing 10-12 % of bed material and cleaning stripper ash cooler periodically will decrease agglomeration in stripper ash cooler of unit.

  20. Mechanisms for selective agglomeration of coals

    SciTech Connect

    Wheelock, T.D.; Drzymala, J.; Allen, R.W.; Hu, Y.-C.; Tyson, D.; Xiaoping, Qiu; Lessa, A.

    1989-10-01

    Measurement and control of the surface properties of coal and pyrite are important in the application of selective oil agglomeration for coal beneficiation and both received further study and consideration. One method of surface characterization involves measuring the heat of immersion of coal in water or other liquids. To develop a useful and consistent measurement technique, numerous measurements were conducted with Illinois No. 6 coal to study the effects of coal particle size and moisture content on the heat of immersion in heptane, water, hexadecane and methanol. The effect of particle size was also studied. Also, ground mineral pyrite was pretreated with dilute solutions of sodium sulfide at various Ph and then agglomerated with heptane. To achieve better control over the oil agglomeration process, oil agglomeration experiments were conducted with aqueous suspensions of graphite which were first degassed with a vacuum pump. 7 refs., 16 figs., 2 tabs.

  1. Successfully use agglomeration for size enlargement

    SciTech Connect

    Pietsch, W.

    1996-04-01

    The processing of fine and ultrafine particles by size enlargement finds an ever increasing application. At the same time, undesirable agglomeration such as buildup, caking, bridging, and uncontrolled aggregation of fine particles can occur during processing and handling of these particulate solids. This article will provide a survey of the phenomena of agglomeration and discuss the unit operation of size enlargement by agglomeration. This article is also an invitation, particularly to young engineers, to become interested in agglomeration. Considering that mechanical process technologies are requiring more energy every year than any other group of consumers and efficiencies are typically in the single digits or teens at best, considerable rewards can be expected from the development of scientifically modified, more energy-efficient methods and equipment.

  2. Cross-bedding related anisotropy and its interplay with various boundary conditions in the formation and orientation of joints in an aeolian sandstone

    NASA Astrophysics Data System (ADS)

    Deng, Shang; Cilona, Antonino; Morrow, Carolyn; Mapeli, Cesar; Liu, Chun; Lockner, David; Prasad, Manika; Aydin, Atilla

    2015-08-01

    Previous research revealed that the cross-bedding related anisotropy in Jurassic aeolian Aztec Sandstone cropping out in the Valley of Fire State Park, Nevada, affects the orientation of compaction bands, also known as anti-cracks or closing mode structures. We hypothesize that cross-bedding should have a similar influence on the orientation of the opening mode joints within the same rock at the same location. To test this hypothesis, we investigated the relationship between the orientation of cross-beds and the orientation of different categories of joint sets including cross-bed package confined joints and joint zones in the Aztec Sandstone. The field data show that the cross-bed package confined joints occur at high-angle to bedding and trend roughly parallel to the dip direction of the cross-beds. In comparison, the roughly N-S trending joint zones appear not to be influenced by the cross-beds in any significant way but frequently truncate against the dune boundaries. To characterize the anisotropy due to cross-bedding in the Aztec Sandstone, we measured the P-wave velocities parallel and perpendicular to bedding from 11 samples and determined an average P-wave anisotropy to be slightly larger than 13%. From these results, a model based on the generalized Hooke's law for anisotropic materials is used to analyze deformation of cross-bedded sandstone as a transversely isotropic material. In the analysis, the dip angle of cross-beds is assumed to be constant and the strike orientation varying from 0° to 359° in the east (x), north (y), and up (z) coordinate system. We find qualitative agreement between most of the model results and the observed field relations between cross-beds and the corresponding joint sets. The results also suggest that uniaxial extension (εzz > εxx = εyy = 0) and axisymmetric extension (εxx = εyy < εzz and εxx = εyy > εzz) would amplify the influence of cross-bedding associated anisotropy on the joint orientation

  3. Use of glow discharge in fluidized beds

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Wood, P. C.; Ballou, E. V.; Spitze, L. A. (Inventor)

    1981-01-01

    Static charges and agglomerization of particles in a fluidized bed systems are minimized by maintaining in at least part of the bed a radio frequency glow discharge. This approach is eminently suitable for processes in which the conventional charge removing agents, i.e., moisture or conductive particle coatings, cannot be used. The technique is applied here to the disproportionation of calcium peroxide diperoxyhydrate to yield calcium superoxide, an exceptionally water and heat sensitive reaction.

  4. Investigation on Agropellet Combustion in the Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Isemin, R. L.; Konayahin, V. V.; Kuzmin, S. N.; Zorin, A. T.; Mikhalev, A. V.

    Agricultural wastes (straw, sunflower or millet husk, etc.) are difficult to use as fuel because of low bulk density and relatively big ash content with a low melting point. It is possible to produce agropellets of agricultural wastes which are suggested to combust in a fluidized bed of pellets alone, their char particles and ash. The characteristics of the process of fluidization of agropellets are investigated at room temperature. The experiments on agropellet combustion in a fluidized bed are carried out in an experimental set-up. The results of the experiments have shown that in such a bed the pellets produced of straw and millet husk combust with the same rate as those of wood though the latter contain 8.76 - 19.4 times less ash. The duration of combustion of the same portion of straw pellets in a fluidized bed is 3.74 - 7.01 times less than the duration of combustion of cut straw in a fixed bed. Besides, the movement of agropellets prevents agglomeration and slagging of a boiler furnace.

  5. Proceedings, volume 17, Institute for Briquetting and Agglomeration

    SciTech Connect

    Not Available

    1982-01-01

    Papers presented discussed pelletizing of coal fines, graphite manufacture, compacting of coal, use of computers in agglomeration, HYL-III process, briquetting of iron ore fines, RECLAFORM, INMETCO process, binders for agglomeration, acoustic agglomeration, pelletizing of lime-fly ash mixtures, extrusion of aluminas for catalysts, and agglomeration of wastes. Seven papers have been abstracted separately.

  6. Operational source receptor calculations for large agglomerations

    NASA Astrophysics Data System (ADS)

    Gauss, Michael; Shamsudheen, Semeena V.; Valdebenito, Alvaro; Pommier, Matthieu; Schulz, Michael

    2016-04-01

    reduction measures but they also indicate the relative importance of indigenous versus imported air pollution. The calculations are currently performed weekly by MET Norway for the Paris, London, Berlin, Oslo, Po Valley and Rhine-Ruhr regions and the results are provided free of charge at the MACC website (http://www.gmes-atmosphere.eu/services/aqac/policy_interface/regional_sr/). A proposal to extend this service to all EU capitals on a daily basis within the Copernicus Atmosphere Monitoring Service is currently under review. The tool is an important example illustrating the increased application of scientific tools to operational services that support Air Quality policy. This paper will describe this tool in more detail, focusing on the experimental setup, underlying assumptions, uncertainties, computational demand, and the usefulness for air quality for policy. Options to apply the tool for agglomerations outside the EU will also be discussed (making reference to, e.g., PANDA, which is a European-Chinese collaboration project).

  7. Coupled changes in sand grain size and sand transport driven by changes in the upstream supply of sand in the Colorado River: relative importance of changes in bed-sand grain size and bed-sand area

    USGS Publications Warehouse

    Topping, D.J.; Rubin, D.M.; Melis, T.S.

    2007-01-01

    Sand transport in the Colorado River in Marble and Grand canyons was naturally limited by the upstream supply of sand. Prior to the 1963 closure of Glen Canyon Dam, the river exhibited the following four effects of sand supply limitation: (1) hysteresis in sediment concentration, (2) hysteresis in sediment grain size coupled to the hysteresis in sediment concentration, (3) production of inversely graded flood deposits, and (4) development or modification of a lag between the time of a flood peak and the time of either maximum or minimum (depending on reach geometry) bed elevation. Construction and operation of the dam has enhanced the degree to which the first two of these four effects are evident, and has not affected the degree to which the last two effects of sand supply limitation are evident in the Colorado River in Marble and Grand canyons. The first three of the effects involve coupled changes in suspended-sand concentration and grain size that are controlled by changes in the upstream supply of sand. During tributary floods, sand on the bed of the Colorado River fines; this causes the suspended sand to fine and the suspended-sand concentration to increase, even when the discharge of water remains constant. Subsequently, the bed is winnowed of finer sand, the suspended sand coarsens, and the suspended-sand concentration decreases independently of discharge. Also associated with these changes in sand supply are changes in the fraction of the bed that is covered by sand. Thus, suspended-sand concentration in the Colorado River is likely regulated by both changes in the bed-sand grain size and changes in the bed-sand area. A physically based flow and suspended-sediment transport model is developed, tested, and applied to data from the Colorado River to evaluate the relative importance of changes in the bed-sand grain size and changes in the bed-sand area in regulating suspended-sand concentration. Although the model was developed using approximations for steady

  8. Volcanic red-bed copper mineralisation related to submarine basalt alteration, Mont Alexandre, Quebec Appalachians, Canada

    NASA Astrophysics Data System (ADS)

    Cabral, Alexandre Raphael; Beaudoin, Georges

    2007-11-01

    Two types of native copper occur in Upper Silurian basaltic rocks in the Mont Alexandre area, Quebec Appalachians: (1) type 1 forms micrometric inclusions in plagioclase and is possibly magmatic in origin, whereas (2) type 2 occurs as coarse-grained patches rimmed by cuprite in altered porphyritic basalt. Type 1 has higher contents of sulphur (2,000-20,263 ppm) and arsenic (146-6,017 ppm), and a broader range of silver abundances (<65-2,186 ppm Ag) than type 2 (149-1,288 ppm S, <90-146 As, <65-928 ppm Ag). No mineral inclusions of sulphide or arsenide in native copper were observed at the electron-microprobe scale. Primary igneous fabrics are preserved, but the basaltic flows are pervasively oxidised and plagioclase is albitised. Chlorite replaces plagioclase and forms interstitial aggregates in the groundmass and has Fe/(Fe+Mg) ratios ranging from 0.29 to 0.36 with calculated temperatures between 155°C and 182°C. Copper sulphides in vacuoles and veinlets are associated with malachite, fibro-radiating albite and yarrowite (Cu9S8 with up to 0.3 wt% Ag). Bulk-rock concentrations of thallium and lithium range from 70 to 310 ppb and 10 to 22 ppm, respectively, and thallium is positively correlated with Fe2O3. Such concentrations of thallium and lithium are typical of spilitisation during heated seawater-basalt interaction. Spilitisation is consistent with the regional geological setting of deepwater-facies sedimentation, but is different from current models for volcanic red-bed copper, which indicate subaerial oxidation of volcanic flows. The volcanic red-bed copper model should be re-examined to account for native copper mineralisation in basalts altered by warm seawater.

  9. Observational Data Analysis and Numerical Model Assessment of the Seafloor Interaction and Mobility of Sand and Weathered Oil Agglomerates (Surface Residual Balls) in the Surf Zone

    NASA Astrophysics Data System (ADS)

    Dalyander, S.; Long, J.; Plant, N. G.; Penko, A.; Calantoni, J.; Thompson, D.; Mclaughlin, M. K.

    2014-12-01

    When weathered oil is transported ashore, such as during the Deepwater Horizon oil spill, it can mix with suspended sediment in the surf zone to create heavier-than-water sand and oil agglomerates in the form of mats several centimeters thick and tens of meters long. Broken off pieces of these mats and smaller agglomerates formed in situ (called Surface Residual Balls, SRBs) can cause beach re-oiling months to years after the initial spill. The physical dynamics of these SRBs in the nearshore, where they are larger (cm-scale) and less dense than natural sediment, are poorly understood. In the current study, SRB mobility and seafloor interaction is investigated through a combination of laboratory and field experiments with pseudo-SRBs developed to be physically stable proxies for genuine agglomerates. Formulations for mobility prediction based on comparing estimated shear stress to the critical Shields and modified Shields parameters developed for mixed sediment beds are assessed against observations. Processes such as burial, exhumation, and interaction with bedforms (e.g., migrating ripples) are also explored. The observations suggest that incipient motion estimates based on a modified Shields parameter have some skill in predicting SRB movement, but that other forcing mechanisms such as pressure gradients may be important under some conditions. Additionally, burial and exhumation due to the relatively high mobility of sand grains are confirmed as key processes controlling SRB dynamics in the surf zone. This work has broad implications for understanding surf zone sediment transport at the short timescale associated with mobilizing sand grains and SRBs as well as at the longer timescales associated with net transport patterns, sediment budgets, and bed elevation changes.

  10. Age-related differences in lean mass, protein synthesis and skeletal muscle markers of proteolysis after bed rest and exercise rehabilitation.

    PubMed

    Tanner, Ruth E; Brunker, Lucille B; Agergaard, Jakob; Barrows, Katherine M; Briggs, Robert A; Kwon, Oh Sung; Young, Laura M; Hopkins, Paul N; Volpi, Elena; Marcus, Robin L; LaStayo, Paul C; Drummond, Micah J

    2015-09-15

    Bed rest-induced muscle loss and impaired muscle recovery may contribute to age-related sarcopenia. It is unknown if there are age-related differences in muscle mass and muscle anabolic and catabolic responses to bed rest. A secondary objective was to determine if rehabilitation could reverse bed rest responses. Nine older and fourteen young adults participated in a 5-day bed rest challenge (BED REST). This was followed by 8 weeks of high intensity resistance exercise (REHAB). Leg lean mass (via dual-energy X-ray absorptiometry; DXA) and strength were determined. Muscle biopsies were collected during a constant stable isotope infusion in the postabsorptive state and after essential amino acid (EAA) ingestion on three occasions: before (PRE), after bed rest and after rehabilitation. Samples were assessed for protein synthesis, mTORC1 signalling, REDD1/2 expression and molecular markers related to muscle proteolysis (MURF1, MAFBX, AMPKα, LC3II/I, Beclin1). We found that leg lean mass and strength decreased in older but not younger adults after bedrest (P < 0.05) and was restored after rehabilitation. EAA-induced mTORC1 signalling and protein synthesis increased before bed rest in both age groups (P < 0.05). Although both groups had blunted mTORC1 signalling, increased REDD2 and MURF1 mRNA after bedrest, only older adults had reduced EAA-induced protein synthesis rates and increased MAFBX mRNA, p-AMPKα and the LC3II/I ratio (P < 0.05). We conclude that older adults are more susceptible than young persons to muscle loss after short-term bed rest. This may be partially explained by a combined suppression of protein synthesis and a marginal increase in proteolytic markers. Finally, rehabilitation restored bed rest-induced deficits in lean mass and strength in older adults. PMID:26173027

  11. Development of fireside performance indices, Task 7.33, Development of methods to predict agglomeration and deposition in FBCS, Task 7.36, Enhanced air toxics control, Task 7.45

    SciTech Connect

    Zygarlicke, C.J.; Mann, M.D.; Laudal, D.L.; Miller, S.J.

    1994-01-01

    The Energy & Environmental Research Center (EERC) has been developing advanced indices that rank coals according to their fouling and slagging propensity in utility boilers. The indices are based on sophisticated analytical techniques for identifying and quantifying coal inorganics and are useful in predicting the effects of proposed operational changes on ash deposition in coal-fired boilers. These indices are intended to provide an economical way to reduce the amount of full-scale testing needed to determine the best means of minimizing ash-related problems. The successful design and operation of the fluidized-bed combustor requires the ability to control and mitigate ash-related problems. The major ash-related problems in FBC are agglomeration of bed material, ash deposition on heat-transfer surfaces, ash deposition on refractory and uncooled surfaces, corrosion, and erosion. The focus of the Development of Methods to Predict Agglomeration and Deposition in FBCs is on the agglomeration and deposition problems in atmospheric bubbling and circulating beds. The 1990 Clean Air Act Amendments require study of air toxic emissions from coal combustion systems. Since most of the toxic metals present in coal will be in particulate form, a high level of fine-particle control appears to be the best approach to achieving a high level of air toxics control. However, over 50% of mercury and a portion of selenium emissions are in vapor form and are not typically collected in particulate control devices. Therefore, the goal of this project is to develop methods that capture the vapor-phase metals while simultaneously achieving ultrahigh collection efficiency of particulate air toxics.

  12. Role of Solvents in Improvement of Dissolution Rate of Drugs: Crystal Habit and Crystal Agglomeration

    PubMed Central

    Maghsoodi, Maryam

    2015-01-01

    Crystallization is often used for manufacturing drug substances. Advances of crystallization have achieved control over drug identity and purity, but control over the physical form remains poor. This review discusses the influence of solvents used in crystallization process on crystal habit and agglomeration of crystals with potential implication for dissolution. According to literature it has been known that habit modification of crystals by use of proper solvents may enhance the dissolution properties by changing the size, number and the nature of crystal faces exposed to the dissolution medium. Also, the faster dissolution rate of drug from the agglomerates of crystals compared with the single crystals may be related to porous structure of the agglomerates and consequently their better wettability. It is concluded from this review that in-depth understanding of role of the solvents in crystallization process can be applied to engineering of crystal habit or crystal agglomeration, and predictably dissolution improvement in poorly soluble drugs. PMID:25789214

  13. Development of a full scale selective oil agglomeration plant

    SciTech Connect

    Donnelly, J.C.; Cooney, B.; Hoare, I.; Waugh, B.; Robinson, R.

    1998-12-31

    A research and development program managed by Australian Mining Investments Limited (AMI) on behalf of an investment syndicate was conducted with the objective of improving the efficiency and economy of the Selective Oil Agglomeration Process (SOAP), and developing viable commercial sized operating plants. Fewer than half the coal preparation plants in Australia beneficiate fine coal by froth flotation, the only viable alternative to SOAP for the recovery of low ash, fine and ultra fine coal. Those plants without flotation generally dispose of the ultra fine material, approximately {minus}100{micro}m in size, as tailings to waste. In the majority of cases this ultra fine waste contains more than 50% relatively low ash coal of saleable quality. It is believed that this coal constitutes a loss of 8--10 million tonnes per annum and that the coal mining industry would welcome a recovery process which has low capital and operating costs and will function automatically with minimal operator attention. The authors carried out a comprehensive literature study of selective oil agglomeration in order to gain a full understanding of the process and to plan the research program. Extensive studies were then undertaken on oil dispersion in the water phase, formation of oil water emulsions with surfactants and the optimization of surfactant selection. Oil and emulsion properties were investigated including stability, viscosity, temperature, concentration of components, time of formation, and cost. This work was followed by characterization studies on coals from the Gunnedah Basin and agglomeration test work on these coals. These agglomeration studies were performed firstly at bench level and then by using a small, 200 kg/hr continuous process development unit. The results were sufficiently encouraging to justify the design and construction of a fully instrumented, PLC controlled, 2 tph pilot plant at Gunnedah Colliery Coal Preparation Plant. Extensive trials were carried out on

  14. Paleontologic and stratigraphic relations of phosphate beds in Upper Cretaceous rocks of the Cordillera Oriental, Colombia

    USGS Publications Warehouse

    Maughan, Edwin K.; Zambrano O., Francisco; Mojica G., Pedro; Abozaglo M., Jacob; Pachon P., Fernando; Duran R., Raul

    1979-01-01

    Phosphorite crops out in the Cordillera Oriental of the Colombian Andes in rocks of Late Cretaceous age as strata composed mostly of pelletal carbonate fluorapatite. One stratum of Santonian age near the base of the Galembo Member of the La Luna Formation crops out at many places in the Departments of Santander and Norte de Santander and may be of commercial grade. This stratum is more than one meter thick at several places near Lebrija and near Sardinata, farther south it is locally one meter thick or more near the base of the Guadalupe Formation in the Department of Boyaca. Other phosphorite beds are found at higher stratigraphic levels in the Galembo Member and the Guadalupe Formation, and at some places these may be commercial also. A stratigraphically lower phosphorite occurs below the Galembo Member in the Capacho Formation (Cenomanian age) in at least one area near the town of San Andres, Santander. A phosphorite or pebbly phosphate conglomerate derived from erosion of the Galembo Member forms the base of the Umir Shale and the equivalent Colon Shale at many places. Deposition of the apatite took place upon the continental shelf in marine water of presumed moderate depth between the Andean geosyncline and near-shore detrital deposits adjacent to the Guayana shield. Preliminary calculations indicate phosphorite reserves of approximately 315 million metric tons in 9 areas, determined from measurements of thickness, length of the outcrop, and by projecting the reserves to a maximum of 1,000 meters down the dip of the strata into the subsurface. Two mines were producing phosphate rock in 1969; one near Turmeque, Boyaca, and the other near Tesalia, Huila.

  15. Effects of baffle configuration and tank size on spherical agglomerates of dimethyl fumarate in a common stirred tank.

    PubMed

    Lin, Po Yen; Lee, Hung Lin; Chen, Chih Wei; Lee, Tu

    2015-11-30

    To pave the way for technology transfer and scale up of the spherical agglomeration (SA) process for dimethyl fumarate, effects of the US, European and Kawashima type baffles and 0.5, 2.0 and 10 L-sized common stirred tank were studied. It was found that the particle size distribution varied significantly. However, the size-related properties such as dissolution profile and flowability of agglomerates from the same size cut after sieving could remain unchanged. The interior structure-related properties such as particle density and mechanical property of agglomerates upon baffle change and scale up from the same size cut were decayed and the agglomerates could become denser and stronger by prolonged maturation time. To maintain the same size distribution, agglomerates from any batch could have been separated and classified by sieving and then blended back together artificially by the desired weight% of each cut. PMID:26417848

  16. Coal hydrogenation and deashing in ebullated bed catalytic reactor

    DOEpatents

    Huibers, Derk T. A.; Johanson, Edwin S.

    1983-01-01

    An improved process for hydrogenation of coal containing ash with agglomeration and removal of ash from an ebullated bed catalytic reactor to produce deashed hydrocarbon liquid and gas products. In the process, a flowable coal-oil slurry is reacted with hydrogen in an ebullated catalyst bed reaction zone at elevated temperature and pressure conditions. The upward velocity and viscosity of the reactor liquid are controlled so that a substantial portion of the ash released from the coal is agglomerated to form larger particles in the upper portion of the reactor above the catalyst bed, from which the agglomerated ash is separately withdrawn along with adhering reaction zone liquid. The resulting hydrogenated hydrocarbon effluent material product is phase separated to remove vapor fractions, after which any ash remaining in the liquid fraction can be removed to produce substantially ash-free coal-derived liquid products.

  17. Dreissena polymorpha Pall. postveligers in submersed macrophyte beds of Put-in-Bay, Ohio, as related to rate and density of settlement, macrophyte preference, water depth, and position within beds

    SciTech Connect

    Moore, D.L.

    1995-06-01

    Increased water clarity due in large part to the invasion and spread of Dreissena polymorpha Pall., has allowed reestablishment of nearly continuous beds of submersed macrophytes in Put-in-Bay, Ohio. These beds now serve as sites for settlement by Dreissena veligers. Four transects extending from a maximum depth of 4.0 m to a minimum depth of 0.5 m were established in 1994, to document the time of recruitment, density of postveliger settlement, preferred macrophyte as a substrate, and effects of water depth and location within transects on recruitment. Settlement densities were determined for 100 g wet weight samples of macrophytes harvested along transects by snorkel and scuba. Peak settlement occurred 23 August, 11 days after the second planktonic veliger peak, but continued until early October. Maximum densities were greatest in 1.5-3.5 m water nearer the lakeward end of the transects and decreased in 1.0 m water or shoreward in dense submersed macrophyte beds. A maximum density of 15,150 Dreissena/100 g macrophyte occurred on the perennial Myriophyllum spicatum L., although mean settlement densities were greatest for the perennials M. spicatum, Ceratophyllum demersum L., and the annuals Vallisneria americana Michx. and Najas quadalupensis (Spreng.) Magnus. Macrophyte preference as a settling substrate is most probably a reflection of relative macrophyte abundance and position within dense beds rather than a particular plant architecture. Assessment of densities after autumnal vegetational growth is not yet complete.

  18. A roughness-corrected index of relative bed stability for regional stream surveys

    EPA Science Inventory

    Quantitative regional assessments of streambed sedimentation and its likely causes are hampered because field investigations typically lack the requisite sample size, measurements, or precision for sound geomorphic and statistical interpretation. We adapted an index of relative b...

  19. Analysis of Urban Agglomeration and Its Meaning for Rural People.

    ERIC Educational Resources Information Center

    Spiegelman, Robert G.

    Agglomeration--the clustering of people, businesses, or structures within an area--is investigated for two purposes: (1) defining the nature of agglomeration and erecting a suitable agglomeration theory, and (2) suggesting further research. These two objectives are seen as being vital to help improve the economic well-being of rural people by…

  20. Method for providing improved solid fuels from agglomerated subbituminous coal

    DOEpatents

    Janiak, Jerzy S.; Turak, Ali A.; Pawlak, Wanda; Ignasiak, Boleslaw L.

    1989-01-01

    A method is provided for separating agglomerated subbituminous coal and the heavy bridging liquid used to form the agglomerates. The separation is performed by contacting the agglomerates with inert gas or steam at a temperature in the range of 250.degree. to 350.degree. C. at substantially atmospheric pressure.

  1. Effect of temperature on wet agglomeration of crystals

    PubMed Central

    Maghsoodi, Maryam; Yari, Zahra

    2014-01-01

    Objective(s): This study dealt with the wet agglomeration process in which a small quantity of binder liquid was added into a suspension of crystals, directly in the stirring vessel where the crystallization took place. The purpose of this investigation was evaluation of the effect of temperature on the agglomeration process in order to gain insight into the mechanism of the formation of the agglomerates. Materials and Methods: Carbamazepine was used as a model drug and water/ethanol and isopropyl acetate were used as crystallization system and binder liquid, respectively. The agglomeration of crystals was carried out at various temperatures and the agglomerates were characterized in terms of size, morphology, density and mechanical strength. Results: Evaluation of the agglomerates along the course of agglomeration shows that the properties of the particles change gradually but substantially. Higher temperature of the system during agglomeration process favors the formation of more regular agglomerates with mechanically stronger and denser structure; this can be explained by the promotion effect of temperature on the agglomeration process. Conclusion: With optimized wet agglomeration temperature, spherical, dense, and strong agglomerates can be obtained. PMID:24967063

  2. Bed bugs.

    PubMed

    Foulke, Galen T; Anderson, Bryan E

    2014-09-01

    The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem. PMID:25577850

  3. Elevated relative humidity increases the incidence of boron deficiency in bedding plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High relative humidity (RH) can cause lower concentrations of B accumulating in plants. The common greenhouse practice of controlling excess temperatures by applying mist irrigation to youngplants (plugs) results in elevated RH levels. Reports of boron (B) deficiency have become more prevalent ove...

  4. Fluidized bed combustion

    SciTech Connect

    Sowards, N.K.; Murphy, M.L.

    1991-10-29

    This patent describes a vessel. It comprises a fluid bed for continuously incinerating fuel comprising tire segments and the like which comprise metallic wire tramp and for concurrently removing tramp and bed materials at a bottom effluent exit means of the vessel, the vessel further comprising static air distributor means at the periphery of the bed comprising a substantially centrally unobstructed relatively large central region in which the fluid bed and fuel only are disposed and through which bed material and tramp migrate without obstruction to and through the effluent exit means, downwardly and inwardly stepped lower vessel wall means and a plurality of peripherally located centrally directed vertically and horizontally offset spaced air influent means surrounding the central region and associated with the stepped lower vessel wall means by which the bed is supported and fluidized.

  5. A laboratory study of sex- and stage-related mortality and morbidity in bed bugs (hemiptera: cimicidae) exposed to deltamethrin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure of a pyrethroid-susceptible strain of bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae) to varying concentrations of deltamethrin for 24h indicated there was no significant difference in mortality between males, females, and nymphs at 24h or 168h post-exposure. Most bed bugs classified ...

  6. Iron Oxide Nanoparticle Agglomeration Influences Dose-Rates and Modulates Oxidative Stress Mediated Dose-Response Profiles In Vitro

    SciTech Connect

    Sharma, Gaurav; Kodali, Vamsi K.; Gaffrey, Matthew J.; Wang, Wei; Minard, Kevin R.; Karin, Norman J.; Teeguarden, Justin G.; Thrall, Brian D.

    2013-07-31

    Spontaneous agglomeration of engineered nanoparticles (ENPs) is a common problem in cell culture media which can confound interpretation of in vitro nanotoxicity studies. The authors created stable agglomerates of iron oxide nanoparticles (IONPs) in conventional culture medium, which varied in hydrodynamic size (276 nm-1.5 μm) but were composed of identical primary particles with similar surface potentials and protein coatings. Studies using C10 lung epithelial cells show that the dose rate effects of agglomeration can be substantial, varying by over an order of magnitude difference in cellular dose in some cases. Quantification by magnetic particle detection showed that small agglomerates of carboxylated IONPs induced greater cytotoxicity and redox-regulated gene expression when compared with large agglomerates on an equivalent total cellular IONP mass dose basis, whereas agglomerates of amine-modified IONPs failed to induce cytotoxicity or redox-regulated gene expression despite delivery of similar cellular doses. Dosimetry modelling and experimental measurements reveal that on a delivered surface area basis, large and small agglomerates of carboxylated IONPs have similar inherent potency for the generation of ROS, induction of stress-related genes and eventual cytotoxicity. The results suggest that reactive moieties on the agglomerate surface are more efficient in catalysing cellular ROS production than molecules buried within the agglomerate core. Because of the dynamic, size and density-dependent nature of ENP delivery to cells in vitro, the biological consequences of agglomeration are not discernible from static measures of exposure concentration (μg/ml) alone, highlighting the central importance of integrated physical characterisation and quantitative dosimetry for in vitro studies. The combined experimental and computational approach provides a quantitative framework for evaluating relationships between the biocompatibility of nanoparticles and their

  7. Modeling Agglomeration of Dust Particles in Plasma

    SciTech Connect

    Matthews, Lorin S.; Land, Victor; Ma Qianyu; Perry, Jonathan D.; Hyde, Truell W.

    2011-11-29

    The charge on an aggregate immersed in a plasma environment distributes itself over the aggregate's surface; this can be approximated theoretically by assuming a multipole distribution. The dipole-dipole (or higher order) charge interactions between fractal aggregates lead to rotations of the grains as they interact. Other properties of the dust grains also influence the agglomeration process, such as the monomer shape (spherical or ellipsoidal) or the presence of magnetic material. Finally, the plasma and grain properties also determine the morphology of the resultant aggregates. Porous and fluffy aggregates are more strongly coupled to the gas, leading to reduced collisional velocities, and greater collisional cross sections. These factors in turn can determine the growth rate of the aggregates and evolution of the dust cloud. This paper gives an overview of the numerical and experimental methods used to study dust agglomeration at CASPER and highlights some recent results.

  8. Engineering development of selective agglomeration. Final report

    SciTech Connect

    Not Available

    1993-10-01

    This report presents the findings of the project entitled {open_quotes}Engineering Development of Selective Agglomeration.{close_quotes} In 1989 the US Department of Energy contracted with Southern Company Services, Inc. (DOE Contract No. DE-AC22-89PC88879) to develop selective agglomeration technology to a commercially acceptable level by 1993. This project is part of DOE`s program to advance the state of physical coal cleaning technologies in order to accelerate the utilization of high-sulfur coals while complying with environmental regulations. Such projects assume added importance in light of the 1990 Clean Air Act Amendments. Appropriate utilization of the abundant reserves of high-sulfur coal in the United States can make a significant contribution to achieving the goal of energy independence.

  9. Agglomeration and Sedimentation of MWCNTS in Chloroform

    NASA Astrophysics Data System (ADS)

    Eremin, Yu. S.; Kolesnikova, A. A.; Grekhov, A. M.

    The kinetics of agglomeration of multiwalled carbon nanotubes dispersed in chloroform has been studied by the methods of optical spectroscopy and dynamic light scattering. With the use of the models of the diffusion of cylindrical particles, the sizes of particles obtained by this method can be recalculated to the DLS data and the concentration at which the dispersion of individual МWCNTs occurs can be determined.

  10. Encapsulation of hazardous wastes into agglomerates

    SciTech Connect

    Guloy, A.

    1992-01-28

    The objective of this study was to investigate the feasibility of using the cementitious properties and agglomeration characteristics of coal conversion byproducts to encapsulate and immobilize hazardous waste materials. The intention was to establish an economical way of co-utilization and co-disposal of wastes. In addition, it may aid in the eradication of air pollution problems associated with the fine-powdery nature of fly ash. Encapsulation into agglomerates is a novel approach of treating toxic waste. Although encapsulation itself is not a new concept, existing methods employ high-cost resins that render them economically unfeasible. In this investigation, the toxic waste was contained in a concrete-like matrix whereby fly ash and other cementitious waste materials were utilized. The method incorporates the principles of solidification, stabilization and agglomeration. Another aspect of the study is the evaluation of the agglomeration as possible lightweight aggregates. Since fly ash is commercially used as an aggregate, it would be interesting to study the effect of incorporating toxic wastes in the strength development of the granules. In the investigation, the fly ash self-cementation process was applied to electroplating sludges as the toxic waste. The process hoped to provide a basis for delisting of the waste as hazardous and, thereby greatly minimize the cost of its disposal. Owing to the stringent regulatory requirements for hauling and disposal of hazardous waste, the cost of disposal is significant. The current practice for disposal is solidifying the waste with portland cement and dumping the hardened material in the landfill where the cost varies between $700--950/ton. Partially replacing portland cement with fly ash in concrete has proven beneficial, therefore applying the same principles in the treatment of toxic waste looked very promising.

  11. Development of a Gas-Promoted Oil Agglomeration Process

    SciTech Connect

    C. Nelson; F. Zhang; J. Drzymala; M. Shen; R. Abbott; T. D. Wheelock

    1997-11-01

    The preliminary laboratory-scale development of a gas-promoted, oil agglomeration process for cleaning coal was carried out with scale model mixing systems in which aqueous suspensions of ultrafine coal particles were treated with a liquid hydrocarbon and a small amount of air. The resulting agglomerates were recovered by screening. During a batch agglomeration test the progress of agglomeration was monitored by observing changes in agitator torque in the case of concentrated suspensions or by observing changes in turbidity in the case of dilute suspensions. Dilute suspensions were employed for investigating the kinetics of agglomeration, whereas concentrated suspensions were used for determining parameters that characterize the process of agglomeration. A key parameter turned out to be the minimum time te required to produce compact spherical agglomerates. Other important parameters included the projected area mean particle diameter of the agglomerates recovered at the end of a test as well as the ash content and yield of agglomerates. Batch agglomeration tests were conducted with geometrically similar mixing tanks which ranged in volume from 0.346 to 11.07 liters. Each tank was enclosed to control the amount of air present. A variable speed agitator fitted with a six blade turbine impeller was used for agitation. Tests were conducted with moderately hydrophobic Pittsburgh No. 8 coal and with more hydrophobic Upper Freeport coal using either n-heptane, i-octane, or hexadecane as an agglomerant.

  12. Acoustic bed velocity and bed load dynamics in a large sand bed river

    USGS Publications Warehouse

    Gaeuman, D.; Jacobson, R.B.

    2006-01-01

    Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate to conditions near the stream bed is necessary to make the method practical for quantitative applications. In this paper, we discuss the response of ADCP bed velocity measurements, defined as the near-bed sediment velocity detected by the instrument's bottom-tracking feature, to changing sediment-transporting conditions in the lower Missouri River. Bed velocity represents a weighted average of backscatter from moving bed load particles and spectral reflections from the immobile bed. The ratio of bed velocity to mean bed load particle velocity depends on the concentration of the particles moving in the bed load layer, the bed load layer thickness, and the backscatter strength from a unit area of moving particles relative to the echo strength from a unit area of unobstructed bed. A model based on existing bed load transport theory predicted measured bed velocities from hydraulic and grain size measurements with reasonable success. Bed velocities become more variable and increase more rapidly with shear stress when the transport stage, defined as the ratio of skin friction to the critical shear stress for particle entrainment, exceeds a threshold of about 17. This transition in bed velocity response appears to be associated with the appearance of longer, flatter bed forms at high transport stages.

  13. Markers of bone resorption and calcium metabolism are related to dietary intake patterns in male and female bed rest subjects

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Zwart, S. R.; Hargens, A. r.

    2006-01-01

    Dietary potassium and protein intakes predict net endogenous acid production in humans. Intracellular buffers, including exchangeable bone mineral, play a crucial role in balancing chronic acid-base perturbations in the body; subsequently, chronic acid loads can potentially contribute to bone loss. Bone is lost during space flight, and a dietary countermeasure would be desirable for many reasons. We studied the ability of diet protein and potassium to predict levels of bone resorption markers in males and females. Identical twin pairs (8 M, 7 F) were assigned to 2 groups: bed rest (sedentary, SED) or bed rest with supine treadmill exercise in a lower body negative pressure chamber (EX). Diet was controlled for 3 d before and 30 d of bed rest (BR). Urinary Ca, N-telopeptide (NTX), and pyridinium crosslinks (PYD) were measured before and on days 5, 12, 19, and 26 of BR. Data were analyzed by Pearson correlation (P<0.05). The ratio of dietary animal protein/potassium intake was not correlated with NTX before BR for males or females, but they were positively correlated in both groups of males during bed rest. Dietary animal protein/potassium and urine Ca were correlated before and during bed rest for the males, and only during bed rest for the females. Conversely, the ratio of dietary vegetable protein/potassium intake was negatively correlated with urinary calcium during bed rest for the females, but there was no relationship between vegetable protein/potassium intake and bone markers for the males. These data suggest that the ratio of animal protein/potassium intake may affect bone, particularly in bed rest subjects. These data show that the type of protein and gender may be additional factors that modulate the effect of diet on bone metabolism during bed rest. Altering this ratio may help prevent bone loss on Earth and during space flight.

  14. Nearshore dynamics of artificial sand and oil agglomerates

    USGS Publications Warehouse

    Dalyander, P. Soupy; Plant, Nathaniel G.; Long, Joseph W.; McLaughlin, Molly R.

    2015-01-01

    Weathered oil can mix with sediment to form heavier-than-water sand and oil agglomerates (SOAs) that can cause beach re-oiling for years after a spill. Few studies have focused on the physical dynamics of SOAs. In this study, artificial SOAs (aSOAs) were created and deployed in the nearshore, and shear stress-based mobility formulations were assessed to predict SOA response. Prediction sensitivity to uncertainty in hydrodynamic conditions and shear stress parameterizations were explored. Critical stress estimates accounting for large particle exposure in a mixed bed gave the best predictions of mobility under shoaling and breaking waves. In the surf zone, the 10-cm aSOA was immobile and began to bury in the seafloor while smaller size classes dispersed alongshore. aSOAs up to 5 cm in diameter were frequently mobilized in the swash zone. The uncertainty in predicting aSOA dynamics reflects a broader uncertainty in applying mobility and transport formulations to cm-sized particles.

  15. Micro-agglomerate flotation for deep cleaning of coal. Final report

    SciTech Connect

    Chander, S.; Hogg, R.

    1997-01-15

    The development of practical technologies for the deep cleaning of coal has been seriously hampered by the problems of carrying out efficient coal/mineral separations at the very fine sizes (often finer than 10 {micro}m) needed to achieve adequate liberation of the mineral matter from the coal matrix. In this investigation a hybrid process--Micro-agglomerate flotation--which is a combination of oil-agglomeration and froth flotation was studied. The basic concept is to use small quantities of oil to promote the formation of dense micro-agglomerates with minimal entrapment of water and mineral particles and to use froth flotation to separate these micro-agglomerates from the water/dispersed-mineral phase. Since the floating units will be relatively large agglomerates (30--50 {micro}m in size) rather than fine coal particles (1--10 {micro}m) the problems of froth overload and water/mineral carryover should be significantly alleviated. There are, however, complications. The process involves at least five phases: two or more solids (coal and mineral), two liquids (oil and water) and one gas (air). It is demonstrated in this study that the process is very sensitive to fluctuations in operating parameters. It is necessary to maintain precise control over the chemistry of the liquid phases as well as the agitation conditions in order to promote selectivity. Both kinetics as well as thermodynamic factors play a critical role in determining overall system response.

  16. Saltation threshold reduction due to the electrostatic agglomeration of fine particles

    NASA Technical Reports Server (NTRS)

    Leach, Rodman N.; Greeley, Ronald

    1991-01-01

    Particles between 80 and 110 microns in diameter are the most easily moved by the wind. As the particle size decreases below 60 microns, they are increasingly more difficult to move by surface winds, and a number of experiments were performed in an attempt to reduce the required wind velocity. These include: (1) the bombardment of a bed of fine particles by particles near the optimum size, the larger particles kicking the fine particles into the windstream where they are entrained; and (2) the electrostatic agglomeration of fine particles into sizes more easily saltated. The results of these experiments are discussed.

  17. Agglomeration defects on irradiated carbon nanotubes

    SciTech Connect

    Steini Moura, Cassio; Balzaretti, Naira Maria; Amaral, Livio; Gribel Lacerda, Rodrigo; Pimenta, Marcos A.

    2012-03-15

    Aligned carbon nanotubes (CNT) were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  18. Mitigation of copper corrosion and agglomeration in APS process water systems.

    SciTech Connect

    Dortwegt, R.; Putnam, C.; Swetin, E.

    2002-10-10

    Copper corrosion has been observed in process water (PW) systems at the Advanced Photon Source (APS) dating to the early postcommissioning phase of the project. In time, copper corrosion products agglomerated significantly in certain preferred locations. Significant agglomerations (or deposits) can occur in copper cooling passages such as magnet conductors and x-ray absorbers having relatively large length-to-diameter ratios and where heat is removed by water cooling. Such agglomerations also occur at restrictions found in noncopper system components such as valve seats, fixed orifices, pump seal faces, etc. Modifications to the APS process water system that significantly reduce the rate of copper corrosion are discussed. These modifications have not prevented corrosion altogether. Other means used to prevent component clogging and malfunction as a result of current copper corrosion rates are listed.

  19. Analysis and synthesis of solutions for the agglomeration process modeling

    NASA Astrophysics Data System (ADS)

    Babuk, V. A.; Dolotkazin, I. N.; Nizyaev, A. A.

    2013-03-01

    The present work is devoted development of model of agglomerating process for propellants based on ammonium perchlorate (AP), ammonium dinitramide (ADN), HMX, inactive binder, and nanoaluminum. Generalization of experimental data, development of physical picture of agglomeration for listed propellants, development and analysis of mathematical models are carried out. Synthesis of models of various phenomena taking place at agglomeration implementation allows predicting of size and quantity, chemical composition, structure of forming agglomerates and its fraction in set of condensed combustion products. It became possible in many respects due to development of new model of agglomerating particle evolution on the surface of burning propellant. Obtained results correspond to available experimental data. It is supposed that analogical method based on analysis of mathematical models of particular phenomena and their synthesis will allow implementing of the agglomerating process modeling for other types of metalized solid propellants.

  20. Multifrequency scanning probe microscopy study of nanodiamond agglomerates

    NASA Astrophysics Data System (ADS)

    Aravind, Vasudeva; Lippold, Stephen; Li, Qian; Strelcov, Evgheny; Okatan, Baris; Legum, Benjamin; Kalinin, Sergei; Clarion University Team; Oak Ridge National Laboratory Team

    Due to their rich surface chemistry and excellent mechanical properties and non-toxic nature, nanodiamond particles have found applications such as biomedicine, tribology and lubrication, targeted drug delivery systems, tissue scaffolds and surgical implants. Although single nanodiamond particles have diameters about 4-5nm, they tend to form agglomerates. While these agglomerates can be useful for some purposes, many applications of nanodiamonds require single particle, disaggregated nanodiamonds. This work is oriented towards studying forces and interactions that contribute to agglomeration in nanodiamonds. In this work, using multifrequency scanning probe microscopy techniques, we show that agglomerate sizes can vary between 50-100nm in raw nanodiamonds. Extremeties of particles and Interfaces between agglomerates show dissipative forces with scanning probe microscope tip, indicating agglomerates could act as points of increased adhesion, thus reducing lubricating efficiency when nanodiamonds are used as lubricant additives. This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

  1. Apparatus and method for compacting, degassing and carbonizing carbonaceous agglomerates

    SciTech Connect

    Theodore, F.W.

    1980-08-19

    An apparatus for compacting, degassing and carbonizing carbonaceous agglomerates is described. The apparatus comprises a rotary kiln having an agglomerate inlet means for introducing green agglomerates into the kiln near the inlet of the kiln and a heating medium inlet for introducing a heating medium comprising a finely divided solid into the kiln at a preselected location intermediate the inlet end of the kiln and the outlet end of the kiln to produce a mixture at a temperature above the carbonizing temperature of the agglomerates and a sieve positioned to receive the products from the rotary kiln and separate the heating medium and the compacted, degassed, carbonized agglomerate product. A method for producing compacted, degassed, carbonized carbonaceous agglomerates by the use of the apparatus is also disclosed.

  2. General concepts of hydrargillite Al(OH) 3, agglomeration

    NASA Astrophysics Data System (ADS)

    Veesler, S.; Roure, S.; Boistelle, R.

    1994-02-01

    Agglomeration is an important stage of the Bayer process aiming at increasing the initial size of Al(OH) 3 particles. In the present work, we investigate the effects of supersaturation, seed charge and stirring rate on the agglomeration of hydrargillite crystallites, the size of which ranges from about 2 to 10 μm. The experiments are carried out in a batch crystallizer at constant temperature and caustic concentration. It is shown that the agglomeration rate increases with increasing seed charge, but rapidly reaches a plateau before decreasing when the seed charge is too high. On the other hand, agglomeration continuously decreases with increasing stirring rate, while it is favoured by increasing supersaturation. In the latter case, growth of the crystallites contributes to coarsening the agglomerates. We propose the general outlines of an agglomeration model taking collision and disagglomeration probabilities into account.

  3. Method for producing ceramic particles and agglomerates

    DOEpatents

    Phillips, Jonathan; Gleiman, Seth S.; Chen, Chun-Ku

    2001-01-01

    A method for generating spherical and irregularly shaped dense particles of ceramic oxides having a controlled particle size and particle size distribution. An aerosol containing precursor particles of oxide ceramics is directed into a plasma. As the particles flow through the hot zone of the plasma, they melt, collide, and join to form larger particles. If these larger particles remain in the hot zone, they continue melting and acquire a spherical shape that is retained after they exit the hot zone, cool down, and solidify. If they exit the hot zone before melting completely, their irregular shape persists and agglomerates are produced. The size and size distribution of the dense product particles can be controlled by adjusting several parameters, the most important in the case of powder precursors appears to be the density of powder in the aerosol stream that enters the plasma hot zone. This suggests that particle collision rate is responsible for determining ultimate size of the resulting sphere or agglomerate. Other parameters, particularly the gas flow rates and the microwave power, are also adjusted to control the particle size distribution.

  4. Gender-related Changes in Dorsal Hand and Foot Vein Function Following 60 Days of Head Down Bed Rest

    NASA Technical Reports Server (NTRS)

    Westby, Christian M.; Phillips, Tiffany; Stenger, Michael B.; Platts, Steven H.

    2009-01-01

    It is well known that female astronauts are more likely to experience post-flight orthostatic hypotension and presyncope compared to male astronauts. It has been suggested that the disproportionally higher incidence of presyncope (83% of female vs. 20% male crewmembers) may be due to sex-related differences in vascular function between the upper and lower limbs. However, much of this evidence is specific to changes in resistance vessels. Given that more than 70% of the circulating blood volume resides in compliance vessels, it is conceivable that even small changes in venous function may contribute to post-flight orthostatic hypotension. In spite of this, little is currently known regarding the influence of microgravity exposure on venous function between males and females. PURPOSE: To determine the influence of 60 days of HDBR on dorsal foot and hand vein function between healthy males (M) and females (F). METHODS: Using 2-D ultrasound, dorsal hand and foot vein diameter responses to intravenous infusions phenylephrine (PE), acetylcholine (ACh), and nitroglycerine (NTG) were determined in 26 adults; 10 females (age:37 +/- 2 yr ) and 16 males (age:34 +/- 2 yr ). Changes in venous function were calculated as the difference between diameter at baseline and following each venoactive drug. Differences in venous function between limb and sexes across HDBR were determined using mixed-effects linear regression. RESULTS: In response to 60 days of HDBR, the change in venousconstrictor response to PE in the dorsal hand veins was not significantly different between M and F. Interestingly, the change in constrictor response in the dorsal foot veins (compared to pre HDBR) was approximately 30% greater in the F, whereas the constrictor response was approximately 45% less in the M (p=0.026). HDBR had no influence on the change in dilator response to ACh, or NTG between M and F and between vascular beds. CONCLUSION: These results demonstrate that 60 days of HDBR contributes to sex-related

  5. Rapid determination of plasmonic nanoparticle agglomeration status in blood.

    PubMed

    Jenkins, Samir V; Qu, Haiou; Mudalige, Thilak; Ingle, Taylor M; Wang, Rongrong; Wang, Feng; Howard, Paul C; Chen, Jingyi; Zhang, Yongbin

    2015-05-01

    Plasmonic nanomaterials as drug delivery or bio-imaging agents are typically introduced to biological systems through intravenous administration. However, the potential for agglomeration of nanoparticles in biological systems could dramatically affect their pharmacokinetic profile and toxic potential. Development of rapid screening methods to evaluate agglomeration is urgently needed to monitor the physical nature of nanoparticles as they are introduced into blood. Here, we establish novel methods using darkfield microscopy with hyperspectral detection (hsDFM), single particle inductively-coupled plasma mass spectrometry (spICP-MS), and confocal Raman microscopy (cRM) to discriminate gold nanoparticles (AuNPs) and their agglomerates in blood. Rich information about nanoparticle agglomeration in situ is provided by hsDFM monitoring of the plasmon resonance of primary nanoparticles and their agglomerates in whole blood; cRM is an effective complement to hsDFM to detect AuNP agglomerates in minimally manipulated samples. The AuNPs and the particle agglomerates were further distinguished in blood for the first time by quantification of particle mass using spICP-MS with excellent sensitivity and specificity. Furthermore, the agglomeration status of synthesized and commercial NPs incubated in blood was successfully assessed using the developed methods. Together, these complementary methods enable rapid determination of the agglomeration status of plasmonic nanomaterials in biological systems, specifically blood. PMID:25771013

  6. Development and Application of Agglomerated Multigrid Methods for Complex Geometries

    NASA Technical Reports Server (NTRS)

    Nishikawa, Hiroaki; Diskin, Boris; Thomas, James L.

    2010-01-01

    We report progress in the development of agglomerated multigrid techniques for fully un- structured grids in three dimensions, building upon two previous studies focused on efficiently solving a model diffusion equation. We demonstrate a robust fully-coarsened agglomerated multigrid technique for 3D complex geometries, incorporating the following key developments: consistent and stable coarse-grid discretizations, a hierarchical agglomeration scheme, and line-agglomeration/relaxation using prismatic-cell discretizations in the highly-stretched grid regions. A signi cant speed-up in computer time is demonstrated for a model diffusion problem, the Euler equations, and the Reynolds-averaged Navier-Stokes equations for 3D realistic complex geometries.

  7. Rapid Determination of Plasmonic Nanoparticle Agglomeration Status in Blood

    PubMed Central

    Jenkins, Samir V.; Qu, Haiou; Mudalige, Thilak; Ingle, Taylor; Wang, RongRong; Wang, Feng; Howard, Paul C.; Chen, Jingyi; Zhang, Yongbin

    2015-01-01

    Plasmonic nanomaterials as drug delivery or bio-imaging agents are typically introduced to biological systems through intravenous administration. However, the potential for agglomeration of nanoparticles in biological systems could dramatically affect their pharmacokinetic profile and toxic potential. Development of rapid screening methods to evaluate agglomeration is urgently needed to monitor the physical nature of nanoparticles as they are introduced into blood. Here, we establish novel methods using darkfield microscopy with hyperspectral detection (hsDFM), single particle inductively-coupled plasma mass spectrometry (spICP-MS), and confocal Raman microscopy (cRM) to discriminate gold nanoparticles (AuNPs) and their agglomerates in blood. Rich information about nanoparticle agglomeration in situ is provided by hsDFM monitoring of the plasmon resonance of primary nanoparticles and their agglomerates in whole blood; cRM is an effective complement to hsDFM to detect AuNP agglomerates in minimally manipulated samples. The AuNPs and the particle agglomerates were further distinguished in blood for the first time by quantification of particle mass using spICP-MS with excellent sensitivity and specificity. Furthermore, the agglomeration status of synthesized and commercial NPs incubated in blood was successfully assessed using the developed methods. Together, these complementary methods enable rapid determination of the agglomeration status of plasmonic nanomaterials in biological systems, specifically blood. PMID:25771013

  8. Method for recovering light hydrocarbons from coal agglomerates

    DOEpatents

    Huettenhain, Horst; Benz, August D.; Getsoian, John

    1991-01-01

    A method and apparatus for removing light hydrocarbons, such as heptane, from coal agglomerates includes an enclosed chamber having a substantially horizontal perforate surface therein. The coal agglomerates are introduced into a water bath within the chamber. The agglomerates are advanced over the surface while steam is substantially continuously introduced through the surface into the water bath. Steam heats the water and causes volatilization of the light hydrocarbons, which may be collected from the overhead of the chamber. The resulting agglomerates may be collected at the opposite end from the surface and subjected to final draining processes prior to transportation or use.

  9. Influence of excipients and processing conditions on the development of agglomerates of racecadotril by crystallo-co-agglomeration

    PubMed Central

    Garala, Kevin; Patel, Jaydeep; Patel, Anjali; Raval, Mihir; Dharamsi, Abhay

    2012-01-01

    Purpose: The purpose of the present investigation was to improve the flow and mechanical properties of racecadotril by a crystallo-co-agglomeration (CCA) technique. Direct tableting is a requirement of pharmaceutical industries. Poor mechanical properties of crystalline drug particles require wet granulation which is uneconomical, laborious, and tedious. Materials and Methods: The objective of this work was to study the influence of various polymers/excipients and processing conditions on the formation of directly compressible agglomerates of the water-insoluble drug, racecadotril, an antidiarrheal agent. The agglomerates of racecadotril were prepared using dichloromethane (DCM)–water as the crystallization system. DCM acted as a good solvent for racecadotril as well as a bridging liquid for the agglomeration of the crystallized drug and water as the nonsolvent. The prepared agglomerates were tested for micromeritic and mechanical properties. Results: The process yielded ~90 to 96% wt/ wt spherical agglomerates containing racecadotril with the diameter between 299 and 521 μ. A higher rotational speed of crystallization system reduces the size of the agglomerates and disturbs the sphericity. Spherical agglomerates were generated with a uniform dispersion of the crystallized drug. CCA showed excellent flowability and crushing strength. Conclusion: Excipients and processing conditions can play a key role in preparing spherical agglomerates of racecadotril by CCA, an excellent alternative to the wet granulation process to prepare intermediates for direct compression. PMID:23580935

  10. Fluidized bed reactor utilizing a plate support and method of operating the reactor

    SciTech Connect

    Korenberg, J.

    1984-10-09

    A bed support, and a fluidizing bed reactor incorporating the bed support, the bed support including a horizontal support surface with a centrally disposed conduit for removing tramp material and/or agglomerated material from the reactor. The horizontal support surface has fluidizing air source jet nozzles for directing pressurized air toward the area above the conduit. In a first embodiment, the conduit has downwardly diverging walls. In a second embodiment, the horizontal support surface further includes a bar grate having central fluidizing air source jet nozzles positioned within the conduit. The method of operating the fluidized bed reactor includes directing pressurized air at an angle to the horizontal support surface both for fluidizing the bed and for moving the tramp material and/or agglomerated material toward the conduit for removal from the reactor through the conduit.

  11. Agglomeration multigrid for viscous turbulent flows

    NASA Technical Reports Server (NTRS)

    Mavriplis, D. J.; Venkatakrishnan, V.

    1994-01-01

    Agglomeration multigrid, which has been demonstrated as an efficient and automatic technique for the solution of the Euler equations on unstructured meshes, is extended to viscous turbulent flows. For diffusion terms, coarse grid discretizations are not possible, and more accurate grid transfer operators are required as well. A Galerkin coarse grid operator construction and an implicit prolongation operator are proposed. Their suitability is evaluated by examining their effect on the solution of Laplace's equation. The resulting strategy is employed to solve the Reynolds-averaged Navier-Stokes equations for aerodynamic flows. Convergence rates comparable to those obtained by a previously developed non-nested mesh multigrid approach are demonstrated, and suggestions for further improvements are given.

  12. Pulse combusted acoustic agglomeration apparatus and process

    DOEpatents

    Mansour, Momtaz N.; Chandran, Ravi

    1994-01-01

    An improved apparatus and process for removal of particulates entrained in a gas stream are provided. The removal process employs a pulse combustor to provide an acoustic pressure wave to acoustically enhance agglomeration of particulates which may be collected and removed using a conventional separation apparatus. The apparatus may be employed as a direct fired system for improved operation of gas-operated equipment such as a gas turbine, or may, alternatively, be employed as an add-on subsystem for combustion exhaust clean-up. Additionally, added particulates may include a sorbent for effecting sorption of other contaminants such as sulfur. Various other particulates for contaminant removal may also be introduced into the system as exemplified by alkali-gettering agents.

  13. Pulse combusted acoustic agglomeration apparatus and process

    DOEpatents

    Mansour, Momtaz N.

    1993-01-01

    An improved apparatus and process for removal of particulates entrained in a gas stream are provided. The removal process employs a pulse combustor to provide an acoustic pressure wave to acoustically enhance bimodal agglomeration of particulates which may be collected and removed using a conventional separation apparatus. A particulate having a size different from the size of the particulate in the gas stream to be cleaned is introduced into the system to effectuate the bimodal process. The apparatus may be employed as a direct fired system for improved operation of gas-operated equipment such as a gas turbine, or may, alternatively, be employed as an add-on subsystem for combustion exhaust clean-up. Additionally, the added particulate may be a sorbent for effecting sorption of other contaminants such as sulfur. Various other particulates for contaminant removal may also be introduced into the system as exemplified by alkali-gettering agents.

  14. CIRCULATING MOVING BED COMBUSTION PROOF OF CONCEPT

    SciTech Connect

    Jukkola, Glen

    2010-06-30

    Circulating Moving Bed (CMB) combustion technology has its roots in traditional circulating fluidized bed technology and involves a novel method of solid fuel combustion and heat transfer. CMB technology represents a step change in improved performance and cost relative to conventional PC and FBC boilers. The CMB heat exchanger preheats the energy cycle working fluid, steam or air, to the high temperature levels required in systems for advanced power generation. Unique features of the CMB are the reduction of the heat transfer surfaces by about 60% as a result of the enhanced heat transfer rates, flexibility of operation, and about 30% lower cost over existing technology. The CMB Phase I project ran from July 2001 through March 2003. Its objective was to continue development of the CMB technology with a series of proof of concept tests. The tests were conducted at a scale that provided design data for scale up to a demonstration plant. These objectives were met by conducting a series of experiments in ALSTOM Power’s Multi-use Test Facility (MTF). The MTF was modified to operate under CMB conditions of commercial interest. The objective of the tests were to evaluate gas-to-solids heat transfer in the upper furnace, assess agglomeration in the high temperature CMB bubbling bed, and evaluate solids-to-tube heat transfer in the moving bed heat exchanger. The Phase I program results showed that there are still some significant technical uncertainties that needed to be resolved before the technology can be confidently scaled up for a successful demonstration plant design. Work remained in three primary areas: • scale up of gas to solid heat transfer • high temperature finned surface design • the overall requirements of mechanical and process design. The CMB Phase II workscope built upon the results of Phase I and specifically addressed the remaining technical uncertainties. It included a scaled MTF heat transfer test to provide the necessary data to scale up gas

  15. Biological effects of agglomerated multi-walled carbon nanotubes.

    PubMed

    Song, Zheng-Mei; Wang, Lin; Chen, Ni; Cao, Aoneng; Liu, Yuanfang; Wang, Haifang

    2016-06-01

    The physicochemical properties of nanomaterials play crucial roles in determining their biological effects. Agglomeration of nanomaterials in various systems is a common phenomenon, however, how agglomeration affects the biological consequence of nanomaterials has not been well investigated because of its complexity. Herein, we prepared variable sized agglomerates of oxidized multi-walled carbon nanotubes (O-MWCNTs) by using Ca(2+) and studied their cellular uptake and cytotoxicity in HeLa cells. We found the altered property of O-MWCNTs agglomerates could be controlled and adjusted by the amount of Ca(2+). Agglomeration remarkably facilitated the cellular uptake of O-MWCNTs at the initial contact stage, due to the easy contact of agglomerates with cells. But agglomeration did not induce evident cytotoxicity when the concentration of O-MWCNTs was less than 150μg/mL. That was assayed by cell proliferation, membrane integrity, apoptosis and ROS generation. This study suggests us that the biological behaviors of nanomaterials could be altered by their states of agglomeration. PMID:26930035

  16. Measuring agglomerate size distribution and dependence of localized surface plasmon resonance absorbance on gold nanoparticle agglomerate size using analytical ultracentrifugation.

    PubMed

    Zook, Justin M; Rastogi, Vinayak; Maccuspie, Robert I; Keene, Athena M; Fagan, Jeffrey

    2011-10-25

    Agglomeration of nanoparticles during measurements in relevant biological and environmental media is a frequent problem in nanomaterial property characterization. The primary problem is typically that any changes to the size distribution can dramatically affect the potential nanotoxicity or other size-determined properties, such as the absorbance signal in a biosensor measurement. Herein we demonstrate analytical ultracentrifugation (AUC) as a powerful method for measuring two critical characteristics of nanoparticle (NP) agglomerates in situ in biological media: the NP agglomerate size distribution, and the localized surface plasmon resonance (LSPR) absorbance spectrum of precise sizes of gold NP agglomerates. To characterize the size distribution, we present a theoretical framework for calculating the hydrodynamic diameter distribution of NP agglomerates from their sedimentation coefficient distribution. We measure sedimentation rates for monomers, dimers, and trimers, as well as for larger agglomerates with up to 600 NPs. The AUC size distributions were found generally to be broader than the size distributions estimated from dynamic light scattering and diffusion-limited colloidal aggregation theory, an alternative bulk measurement method that relies on several assumptions. In addition, the measured sedimentation coefficients can be used in nanotoxicity studies to predict how quickly the agglomerates sediment out of solution under normal gravitational forces, such as in the environment. We also calculate the absorbance spectra for monomer, dimer, trimer, and larger gold NP agglomerates up to 600 NPs, to enable a better understanding of LSPR biosensors. Finally, we validate a new method that uses these spectra to deconvolute the net absorbance spectrum of an unknown bulk sample and approximate the proportions of monomers, dimers, and trimers in a polydisperse sample of small agglomerates, so that every sample does not need to be measured by AUC. These results

  17. Dual-Fuel Fluidized Bed Combustor Prototype for Residential Heating: Steady-State and Dynamic Behavior

    NASA Astrophysics Data System (ADS)

    Cammarota, Antonio; Chirone, Riccardo; Miccio, Michele; Sollmene, Roberto; Urcluohr, Massimo

    Fluidized bed combustion of biogenic fuels can be recognized as an attractive option for an ecologically sustainable use of biofuels in residential applications. Nevertheless, biomass combustion in fluidized bed reactors presents some drawbacks that are mainly related to mixing/segregation of fuel particles/volatile matter during devolatilization inside the bed and in the freeboard or to bed agglomeration. A prototype of a 30-50 kWth fluidized bed boiler for residential heating has been designed to burn either a gaseous combustible or a solid biomass fuel or both fuels at the same time. The prototype has been equipped with a gas burner located in the wind-box to optimize the start-up stage of the boiler and with a fluidized bed characterized by a conical geometry ("Gulf Stream" circulation) to improve the mixing of the fuel particles during both devolatilization and char burn-out. The operation of the combustor adopting wood pellets as fuel has been investigated to evaluate their use in residential combustion applications. Steady-state thermally stable regimes of operation have been recognized analyzing both boiler temperatures and gaseous emissions. The optimization of the steady-state operation of the boiler in terms of gaseous emissions has been achieved by varying the nominal thermal power and air excess. An ad-hoc experimental campaign has been carried out to analyze the dynamic performance of the prototype as a response to changes of the demanded thermal power. On the basis of the experimental data, an interpretation of the dynamic behavior of the fluidized bed boiler has been proposed.

  18. AMG by element agglomeration and constrained energy minimization interpolation

    SciTech Connect

    Kolev, T V; Vassilevski, P S

    2006-02-17

    This paper studies AMG (algebraic multigrid) methods that utilize energy minimization construction of the interpolation matrices locally, in the setting of element agglomeration AMG. The coarsening in element agglomeration AMG is done by agglomerating fine-grid elements, with coarse element matrices defined by a local Galerkin procedure applied to the matrix assembled from the individual fine-grid element matrices. This local Galerkin procedure involves only the coarse basis restricted to the agglomerated element. To construct the coarse basis, one exploits previously proposed constraint energy minimization procedures now applied to the local matrix. The constraints are that a given set of vectors should be interpolated exactly, not only globally, but also locally on every agglomerated element. The paper provides algorithmic details, as well as a convergence result based on a ''local-to-global'' energy bound of the resulting multiple-vector fitting AMG interpolation mappings. A particular implementation of the method is illustrated with a set of numerical experiments.

  19. Agglomeration multigrid for the three-dimensional Euler equations

    NASA Technical Reports Server (NTRS)

    Venkatakrishnan, V.; Mavriplis, D. J.

    1994-01-01

    A multigrid procedure that makes use of coarse grids generated by the agglomeration of control volumes is advocated as a practical approach for solving the three dimensional Euler equations on unstructured grids about complex configurations. It is shown that the agglomeration procedure can be tailored to achieve certain coarse grid properties such as the sizes of the coarse grids and aspect ratios of the coarse grid cells. The agglomeration is done as a preprocessing step and runs in linear time. The implications for multigrid of using arbitrary polyhedral coarse grids are discussed. The agglomeration multigrid technique compares very favorably with existing multigrid procedures both in terms of convergence rates and elapsed times. The main advantage of the present approach is the ease with which coarse grids of any desired degree of coarseness may be generated in three dimensions, without being constrained by considerations of geometry. Inviscid flows over a variety of complex configurations are computed using the agglomeration multigrid strategy.

  20. AFBC bed material performance with low-rank coals

    SciTech Connect

    Goblirsch, G.M.; Benson, S.A.; Karner, F.R.; Rindt, D.K.; Hajicek, D.R.

    1983-01-01

    The purpose of this paper is to describe the reasons for carefully screening any candidate bed material for use in low-rank coal atmospheric fluidized-bed combustion, before the final selection is made. The sections of this paper describe: (1) the experimental equipment used to obtain the data, as well as the experimental and analytical procedures used in evaluation; (2) the results of tests utilizing various bed materials with particular emphasis on the problem of bed material agglomeration; and (3) the conclusions and recommendations for bed material selection and control for use with low-rank coal. Bed materials of aluminum oxide, quartz, limestone, dolomite, granite, gabbro, and mixtures of some of these materials have been used in the testing. Of these materials, gabbro appears most suitable for use with high available sodium lignites. 17 figures, 8 tables. (DMC)

  1. Effect of drug content and agglomerate size on tabletability and drug release characteristics of bromhexine hydrochloridetalc agglomerates prepared by crystallo-co-agglomeration.

    PubMed

    Jadhav, Namdeo; Pawar, Atmaram; Paradkar, Anant

    2010-03-01

    The objective of the investigation was to study the effect of bromhexine hydrochloride (BXH) content and agglomerate size on mechanical, compressional and drug release properties of agglomerates prepared by crystallo-co-agglomeration (CCA). Studies on optimized batches of agglomerates (BXT1 and BXT2) prepared by CCA have showed adequate sphericity and strength required for efficient tabletting. Trend of strength reduction with a decrease in the size of agglomerates was noted for both batches, irrespective of drug loading. However, an increase in mean yield pressure (14.189 to 19.481) with an increase in size was observed for BXT2 having BXH-talc (1:15.7). Surprisingly, improvement in tensile strength was demonstrated by compacts prepared from BXT2, due to high BXH load, whereas BXT1, having a low amount of BXH (BXH-talc, 1:24), showed low tensile strength. Consequently, increased tensile strength was reflected in extended drug release from BXT2 compacts (Higuchi model, R(2) = 0.9506 to 0.9981). Thus, it can be concluded that interparticulate bridges formed by BXH and agglomerate size affect their mechanical, compressional and drug release properties. PMID:20228039

  2. A new stochastic approach for the simulation of agglomeration between colloidal particles.

    PubMed

    Henry, Christophe; Minier, Jean-Pierre; Pozorski, Jacek; Lefèvre, Grégory

    2013-11-12

    This paper presents a stochastic approach for the simulation of particle agglomeration, which is addressed as a two-step process: first, particles are transported by the flow toward each other (collision step) and, second, short-ranged particle-particle interactions lead either to the formation of an agglomerate or prevent it (adhesion step). Particle collisions are treated in the framework of Lagrangian approaches where the motions of a large number of particles are explicitly tracked. The key idea to detect collisions is to account for the whole continuous relative trajectory of particle pairs within each time step and not only the initial and final relative distances between two possible colliding partners at the beginning and at the end of the time steps. The present paper is thus the continuation of a previous work (Mohaupt M., Minier, J.-P., Tanière, A. A new approach for the detection of particle interactions for large-inertia and colloidal particles in a turbulent flow, Int. J. Multiphase Flow, 2011, 37, 746-755) and is devoted to an extension of the approach to the treatment of particle agglomeration. For that purpose, the attachment step is modeled using the DLVO theory (Derjaguin and Landau, Verwey and Overbeek) which describes particle-particle interactions as the sum of van der Waals and electrostatic forces. The attachment step is coupled with the collision step using a common energy balance approach, where particles are assumed to agglomerate only if their relative kinetic energy is high enough to overcome the maximum repulsive interaction energy between particles. Numerical results obtained with this model are shown to compare well with available experimental data on agglomeration. These promising results assert the applicability of the present modeling approach over a whole range of particle sizes (even nanoscopic) and solution conditions (both attractive and repulsive cases). PMID:24111685

  3. Concentrations and Distribution of Slag-Related Trace Elements and Mercury in Fine-Grained Beach and Bed Sediments of Lake Roosevelt, Washington, April-May 2001

    USGS Publications Warehouse

    Majewski, Michael S.; Kahle, Sue C.; Ebbert, James C.; Josberger, Edward G.

    2003-01-01

    A series of studies have documented elevated concentrations of trace elements such as arsenic, cadmium, copper, lead, mercury, and zinc in the water, bed sediment, or fish of Lake Roosevelt and the upstream reach of the Columbia River. Elevated concentrations of some trace elements in this region are largely attributable to the transport of slag and metallurgical waste discharged into the Columbia River from a smelter in Canada. Although most recent studies have focused on contamination levels in water, bed sediment, and fish, there is growing concern in the region over the potential threat of airborne contaminants to human health. In response to these concerns, the U.S. Geological Survey conducted an assessment of trace-element concentrations in the relatively shallow fine-grained sediment along the shore of Lake Roosevelt that is exposed annually during periods of reservoir drawdown. During each winter and spring, the water level of Lake Roosevelt is lowered as much as about 80 feet to provide space to capture high river flows from spring runoff, exposing vast expanses of lake-bottom sediment for a period of several months. Upon drying, these exposed areas provide an extremely large source for wind-blown dust. This study concluded that trace elements associated with slag and metallurgical waste are present in the fine-grained fraction (less than 63 micrometers) of bed sediments along the length of Lake Roosevelt, and as such, could be components of the airborne dust resulting from exposure, drying, and wind mobilization of the sediments exposed during the annual drawdowns of the reservoir. Trace-element concentrations in the surficial bed sediment varied, but the major components in slag?arsenic, cadmium, copper, lead, and zinc?showed generally pronounced gradients of decreasing concentrations from near the International Border to the Grand Coulee Dam. The results of this study provide base-line information needed to plan and conduct air monitoring of trace

  4. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; J. A. Gurtler; K. Lewandowski

    2005-09-30

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

  5. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-03-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

  6. Engineering development of selective agglomeration. Executive summary: Final report

    SciTech Connect

    Not Available

    1993-04-01

    Project performance targets for the selective agglomeration process were to achieve 85% or greater Btu recovery at 85% or greater pyritic sulfur rejection (PSR) on a run-of-mine (ROM) coal basis, while producing a final clean-coal product with an ash content of 6% or less which is handleable by conventional coal handling systems. Engineering development of selective agglomeration included: (1) Batch and continuous bench-scale precess development testing; (2) Continuous pilot-scale (3-t/h) component development testing to evaluate the adaptation and/or modification of existing unit operations for selective agglomeration; (3) Continuous pilot-scale (2-t/h) POC testing to optimize the selective agglomeration process and demonstrate precess reliability; (4) Vendor testing to evaluate pelletization and thermal drying precesses as applied to selective agglomeration; (5) Conceptual design of a commercial-scale (200-V/h) selective agglomeration facility; (6) Economic analysis of the selective agglomeration precess at a commercial (200-t/h) scale. The information obtained from the various modes of testing and analysis, particularly POC operations, resulted in a technical and economic design base sufficient to support construction and operation of a commercial plant.

  7. Laboratory investigation of briquettes, wafers, and pellets from coal fines for fixed-bed gasification. Task 1-C and Task 1-D

    SciTech Connect

    Not Available

    1983-03-31

    This report presents the results of studies to determine the technical and economic aspects of coal agglomeration. The agglomerated coal is to be used as a feed coal to a fixed-bed type coal gasification facility. Up to eight coals are examined for agglomerating properties in three different agglomeration techniques: water briquetting in a Carver press; roll briquetting in a double roll briquetter, and pelletizing on a one meter inclined disc pelletizer. The wafer briquetting functioned as a screening examination for various coal/binder combinations to be examined in roll briquetting and pelletizing. Prepared agglomerates were examined in a series of tests to determine their ability to withstand handling and gasification. These tests included: crush strength tests of green agglomerates, hot agglomerates and cured or post (agglomeration) treated agglomerates; high temperature exposure tests; tumble tests on green, posttreated and agglomerates after high temperature exposure; Burghardt tests; small scale gasifier tests; and a high temperature degradation test. Many agglomerates failed the least severe of these tests and thus, were not subjected to the more severe tests.

  8. Fragmentation and bond strength of airborne diesel soot agglomerates

    PubMed Central

    Rothenbacher, Sonja; Messerer, Armin; Kasper, Gerhard

    2008-01-01

    Background The potential of diesel soot aerosol particles to break up into smaller units under mechanical stress was investigated by a direct impaction technique which measures the degree of fragmentation of individual agglomerates vs. impact energy. Diesel aerosol was generated by an idling diesel engine used for passenger vehicles. Both the aerosol emitted directly and aerosol that had undergone additional growth by Brownian coagulation ("aging") was investigated. Optionally a thermo-desoption technique at 280°C was used to remove all high-volatility and the majority of low-volatility HC adsorbates from the aerosol before aging. Results It was found that the primary soot agglomerates emitted directly from the engine could not be fragmented at all. Soot agglomerates permitted to grow additionally by Brownian coagulation of the primary emitted particles could be fragmented to a maximum of 75% and 60% respectively, depending on whether adsorbates were removed from their surface prior to aging or not. At most, these aged agglomerates could be broken down to roughly the size of the agglomerates from the primary emission. The energy required for a 50% fragmentation probability of all bonds within an agglomerate was reduced by roughly a factor of 2 when aging "dry" agglomerates. Average bond energies derived from the data were 0.52*10-16 and 1.2*10-16 J, respectively. This is about 2 orders of magnitude higher than estimates for pure van-der-Waals agglomerates, but agrees quite well with other observations. Conclusion Although direct conclusions regarding the behavior of inhaled diesel aerosol in contact with body fluids cannot be drawn from such measurements, the results imply that highly agglomerated soot aerosol particles are unlikely to break up into units smaller than roughly the size distribution emitted as tail pipe soot. PMID:18533015

  9. Agglomeration of proteins in acoustically levitated droplets.

    PubMed

    Delissen, Friedmar; Leiterer, Jork; Bienert, Ralf; Emmerling, Franziska; Thünemann, Andreas F

    2008-09-01

    An ultrasonic trap (acoustic levitator) was used as an analytical tool to allow container-free handling of proteins in small sample volumes. This trap was combined for the first time with synchrotron small-angle X-ray scattering (SAXS) for structure analysis of biological macromolecules in a solution. The microfocus beamline at BESSY was used as a source of intense X-ray radiation. Apoferritin (APO) was used as a model protein, and its aggregation behavior in a levitator was followed from a diluted solution to the solid state. Different stages of APO agglomeration were observed without solid container walls, which may influence aggregation behavior and produce a parasitic scattering background. Starting with a volume of 5 microL we analyzed the concentration dependence of APO structure factors in the range from 5 to 1,200 mg/mL (solid protein). The solution was stirred automatically due to convection inside the droplet caused by the ultrasonic field. SAXS data recording of APO was performed in time intervals of 60 s during an aggregation experiment of 30 to 60 min. PMID:18607573

  10. Staged fluidized bed

    DOEpatents

    Mallon, R.G.

    1983-05-13

    The invention relates to oil shale retorting and more particularly to staged fluidized bed oil shale retorting. Method and apparatus are disclosed for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

  11. Nucleocapsid Protein from Fig Mosaic Virus Forms Cytoplasmic Agglomerates That Are Hauled by Endoplasmic Reticulum Streaming

    PubMed Central

    Ishikawa, Kazuya; Miura, Chihiro; Maejima, Kensaku; Komatsu, Ken; Hashimoto, Masayoshi; Tomomitsu, Tatsuya; Fukuoka, Misato; Yusa, Akira; Yamaji, Yasuyuki

    2014-01-01

    ABSTRACT Although many studies have demonstrated intracellular movement of viral proteins or viral replication complexes, little is known about the mechanisms of their motility. In this study, we analyzed the localization and motility of the nucleocapsid protein (NP) of Fig mosaic virus (FMV), a negative-strand RNA virus belonging to the recently established genus Emaravirus. Electron microscopy of FMV-infected cells using immunogold labeling showed that NPs formed cytoplasmic agglomerates that were predominantly enveloped by the endoplasmic reticulum (ER) membrane, while nonenveloped NP agglomerates also localized along the ER. Likewise, transiently expressed NPs formed agglomerates, designated NP bodies (NBs), in close proximity to the ER, as was the case in FMV-infected cells. Subcellular fractionation and electron microscopic analyses of NP-expressing cells revealed that NBs localized in the cytoplasm. Furthermore, we found that NBs moved rapidly with the streaming of the ER in an actomyosin-dependent manner. Brefeldin A treatment at a high concentration to disturb the ER network configuration induced aberrant accumulation of NBs in the perinuclear region, indicating that the ER network configuration is related to NB localization. Dominant negative inhibition of the class XI myosins, XI-1, XI-2, and XI-K, affected both ER streaming and NB movement in a similar pattern. Taken together, these results showed that NBs localize in the cytoplasm but in close proximity to the ER membrane to form enveloped particles and that this causes passive movements of cytoplasmic NBs by ER streaming. IMPORTANCE Intracellular trafficking is a primary and essential step for the cell-to-cell movement of viruses. To date, many studies have demonstrated the rapid intracellular movement of viral factors but have failed to provide evidence for the mechanism or biological significance of this motility. Here, we observed that agglomerates of nucleocapsid protein (NP) moved rapidly

  12. In-Situ Agglomeration and De-agglomeration by Milling of Nano-Engineered Lubricant Particulate Composites for Cold Spray Deposition

    NASA Astrophysics Data System (ADS)

    Neshastehriz, M.; Smid, I.; Segall, A. E.

    2014-10-01

    Nano-engineered self-lubricating particles comprised of hexagonal-boron-nitride powder (hBN) encapsulated in nickel have been developed for cold spray coating of aluminum components. The nickel encapsulant consists of several nano-sized layers, which are deposited on the hBN particles by electroless plating. In the cold spray deposition, the nickel becomes the matrix in which hBN acts as the lubricant. The coating demonstrated a very promising performance by reducing the coefficient of friction by almost 50% and increasing the wear resistance more than tenfold. The coatings also exhibited higher bond strength, which was directly related to the hardenability of the particles. During the encapsulation process, the hBN particles agglomerate and form large clusters. De-agglomeration has been studied through low- and high-energy ball milling to create more uniform and consistent particle sizes and to improve the cold spray deposition efficiency. The unmilled and milled particles were characterized with Scanning Electron Microscopy, Energy-Dispersive X-Ray Spectroscopy, BET, and hardness tests. It was found that in low-energy ball milling, the clusters were compacted to a noticeable extent. However, the high-energy ball milling resulted in breakup of agglomerations and destroyed the nickel encapsulant.

  13. Numerical Model for Channel/Floodplain Exchange on a Gravel Bed River: Relative Importance of Upstream and Downstream Boundaries and of Lateral Exchange (Invited)

    NASA Astrophysics Data System (ADS)

    Lauer, J. W.

    2013-12-01

    represent a significant part of the bed material sediment budget. Model runs can assess the relative importance of a) the response of the system to afforestation (through modification of the hydraulic roughness of the floodplain) b) hydrologic impact of the dams (which requires a description of the impact of reservoir management on the full flow duration distribution, an issue addressed statistically using the observed annual flood maxima), c) the effect of sediment starvation, which causes channel incision and the formation of a bed pavement and/or partly alluvial zone, and d) changes in water level in the Rhône River downstream from the confluence. Model runs show that the effects of sediment starvation propagate downstream much more rapidly if the floodplain does not provide sediment to the channel and/or if bedrock is located near the alluvial surface. However, under certain conditions, sand-size sediment eroded from the floodplain can mobilize coarser bed material, leading to more bed incision than is the case without channel/floodplain sediment exchange. In general, runs show that the dynamics of the upstream end of the system depend strongly on sediment supply, while the dynamics of the downstream end (i.e. near the Rhône) are also influenced by floodplain vegetation, downstream water level, and the overall history of incision within the reach.

  14. Column oil agglomeration of fly ash with ultrasonics

    SciTech Connect

    Gray, M.L.; Champagne, K.J.; Soong, Y.; Finseth, D.H.

    1999-07-01

    A promising oil agglomeration process has been developed for the beneficiation of fly ash using a six-foot agglomeration column. Carbon concentrates have been separated from fly ash with yields greater than 60 % and purities of 55 to 74 %. The parameters examined in the study include ultrasonic exposure, pulse rate, frequency, agitation speed, and blade configuration. The effects of the experimental variables on the quality of separation are discussed.

  15. Dispersion of TiO₂ nanoparticle agglomerates by Pseudomonas aeruginosa.

    PubMed

    Horst, Allison M; Neal, Andrea C; Mielke, Randall E; Sislian, Patrick R; Suh, Won Hyuk; Mädler, Lutz; Stucky, Galen D; Holden, Patricia A

    2010-11-01

    Engineered nanoparticles are increasingly incorporated into consumer products and are emerging as potential environmental contaminants. Upon environmental release, nanoparticles could inhibit bacterial processes, as evidenced by laboratory studies. Less is known regarding bacterial alteration of nanoparticles, including whether bacteria affect physical agglomeration states controlling nanoparticle settling and bioavailability. Here, the effects of an environmental strain of Pseudomonas aeruginosa on TiO₂ nanoparticle agglomerates formed in aqueous media are described. Environmental scanning electron microscopy and cryogenic scanning electron microscopy visually demonstrated bacterial dispersion of large agglomerates formed in cell culture medium and in marsh water. For experiments in cell culture medium, quantitative image analysis verified that the degrees of conversion of large agglomerates into small nanoparticle-cell combinations were similar for 12-h-growth and short-term cell contact experiments. Dispersion in cell growth medium was further characterized by size fractionation: for agglomerated TiO₂ suspensions in the absence of cells, 81% by mass was retained on a 5-μm-pore-size filter, compared to only 24% retained for biotic treatments. Filtrate cell and agglomerate sizes were characterized by dynamic light scattering, revealing that the average bacterial cell size increased from 1.4 μm to 1.9 μm because of nano-TiO₂ biosorption. High-magnification scanning electron micrographs showed that P. aeruginosa dispersed TiO₂ agglomerates by preferential biosorption of nanoparticles onto cell surfaces. These results suggest a novel role for bacteria in the environmental transport of engineered nanoparticles, i.e., growth-independent, bacterially mediated size and mass alterations of TiO₂ nanoparticle agglomerates. PMID:20851981

  16. Acoustic agglomeration of power plant fly ash. Final report

    SciTech Connect

    Reethof, G.; McDaniel, O.H.

    1982-01-01

    The work has shown that acoustic agglomeration at practical acoustic intensities and frequencies is technically and most likely economically viable. The following studies were performed with the listed results: The physics of acoustic agglomeration is complex particularly at the needed high acoustic intensities in the range of 150 to 160 dB and frequencies in the 2500 Hz range. The analytical model which we developed, although not including nonlinear acoustic efforts, agreed with the trends observed. We concentrated our efforts on clarifying the impact of high acoustic intensities on the generation of turbulence. Results from a special set of tests show that although some acoustically generated turbulence of sorts exists in the 150 to 170 dB range with acoustic streaming present, such turbulence will not be a significant factor in acoustic agglomeration compared to the dominant effect of the acoustic velocities at the fundamental frequency and its harmonics. Studies of the robustness of the agglomerated particles using the Anderson Mark III impactor as the source of the shear stresses on the particles show that the agglomerates should be able to withstand the rigors of flow through commercial cyclones without significant break-up. We designed and developed a 700/sup 0/F tubular agglomerator of 8'' internal diameter. The electrically heated system functioned well and provided very encouraging agglomeration results at acoustic levels in the 150 to 160 dB and 2000 to 3000 Hz ranges. We confirmed earlier results that an optimum frequency exists at about 2500 Hz and that larger dust loadings will give better results. Studies of the absorption of acoustic energy by various common gases as a function of temperature and humidity showed the need to pursue such an investigation for flue gas constituents in order to provide necessary data for the design of agglomerators. 65 references, 56 figures, 4 tables.

  17. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; J. A. Gurtler

    2004-03-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. A primary example of this is copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process. As a result, operators of acidic heap-leach facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of other agglomeration applications, particularly advanced primary ironmaking.

  18. NOVEL BINDERS AND METHODS FOR AGGLOMERATION OF ORE

    SciTech Connect

    S.K. Kawatra; T.C. Eisele; J.A. Gurtler; C.A. Hardison; K. Lewandowski

    2004-04-01

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking.

  19. NOVEL BINDERS AND METHODS FOR AGGLOMERATION OF ORE

    SciTech Connect

    S.K. Kawatra; T.C. Eisele; J.A. Gurtler; K. Lewandowski

    2005-04-01

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not breakdown during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process. As a result, operators of many facilities see large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching.

  20. Bed Bugs FAQs

    MedlinePlus

    ... Tropical Diseases Laboratory Diagnostic Assistance [DPDx] Parasites Home Bed Bugs FAQs Recommend on Facebook Tweet Share Compartir On ... are bed bugs treated and prevented? What are bed bugs? Bed bugs ( Cimex lectularius ) are small, flat, parasitic ...

  1. Fluidized bed coal desulfurization

    NASA Technical Reports Server (NTRS)

    Ravindram, M.

    1983-01-01

    Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

  2. CONSOLIDATION OF K BASIN SLUDGE DATA AND EXPERIENCES ON AGGLOMERATE FORMATION

    SciTech Connect

    HILL SR

    2010-06-10

    canister sludge. The unconfined compressive strength of samples from this testing, measured by a pocket penetrometer, infers that their shear strength may be between 120 kPa and 170 kPa (PNNL-16496). These short-duration hydrothermal tests were conducted at temperatures much greater than the temperature of the T Plant canyon cells (-7 C to 33 C); however, the strength results provide an initial bounding target for sludge stored for many years, and an upper range for simulants (042910-53451-TP02 Rev 1). Sampling and characterization activities conducted in 2009 have measured the total uranium content and speciation for sludge stored in Engineered Containers SCS-CON-220, -240, -250, and -260 (PNNL-19035). Based on on-going testing that has measured the shear strength of uranium samples containing varying uranium (IV) to uranium (VI) ratios and the characterization of the Engineered Containers SCS-CON-220, -240, -250, and -260, it is unlikely that agglomerates will form on a large scale in this sludge. The highest measured total uranium concentration in the Engineered Container SCS-CON-220 sludge is 35.2 wt% and only 4 wt% to 6 wt% (dry) in Engineered Containers SCS-CON -240, -250, and -260. The uranium concentrations in Engineered Containers SCS-CON-220, -240, -250, and -260 sludge are below the threshold for agglomerate formation. Settler sludge however is estimated to contain {approx} 80 wt% (dry) total uranium, which could lead to the formation of high strength agglomerates depending on the relative concentrations of U(IV) and U(VI) compounds. One of the chief concerns of the STP is sludge dry-out. Samples archived in PNNL hot cells have been known to dry out and form hard clods of material, which are then difficult to reconstitute (HNF-6705). In 1996, all but one of the samples archived at the 222-S Laboratory dried out. These samples were composed of sludge collected from the KE Basin floor and Weasel Pit. However, in the STP's current design plans for sludge stored in

  3. Seasonal changes in soil acidity and related properties in ginseng artificial bed soils under a plastic shade

    PubMed Central

    You, Jiangfeng; Liu, Xing; Zhang, Bo; Xie, Zhongkai; Hou, Zhiguang; Yang, Zhenming

    2014-01-01

    Background In Changbai Mountains, Panax ginseng (ginseng) was cultivated in a mixture of the humus and albic horizons of albic luvisol in a raised garden with plastic shade. This study aimed to evaluate the impact of ginseng planting on soil characteristics. Methods The mixed-bed soils were seasonally collected at intervals of 0–5 cm, 5–10 cm, and 10–15 cm for different-aged ginsengs. Soil physico-chemical characteristics were studied using general methods. Aluminum was extracted from the soil solids with NH4Cl (exchangeable Al) and Na-pyrophosphate (organic Al) and was measured with an atomic absorption spectrophotometer. Results A remarkable decrease in the pH, concentrations of exchangeable calcium, NH4+, total organic carbon (TOC), and organic Al, as well as a pronounced increase in the bulk density were observed in the different-aged ginseng soils from one spring to the next. The decrease in pH in the ginseng soils was positively correlated with the NH4+ (r = 0.463, p < 0.01), exchangeable calcium (r = 0.325, p < 0.01) and TOC (r = 0.292, p < 0.05) concentrations. The NO3− showed remarkable surface accumulation (0–5 cm) in the summer and even more in the autumn but declined considerably the next spring. The exchangeable Al fluctuated from 0.10 mg g−1 to 0.50 mg g−1 for dry soils, which was positively correlated with the NO3− (r = 0.401, p < 0.01) and negatively correlated with the TOC (r = −0.329, p < 0.05). The Al saturation varied from 10% to 41% and was higher in the summer and autumn, especially in the 0–5 cm and 5–10 cm layers. Conclusion Taken together, our study revealed a seasonal shift in soil characteristics in ginseng beds with plastic shade. PMID:25535481

  4. The relative contribution of methanotrophs to microbial communities and carbon cycling in soil overlying a coal-bed methane seep

    USGS Publications Warehouse

    Mills, Christopher T.; Slater, Gregory F.; Dias, Robert F.; Carr, Stephanie A.; Reddy, Christopher M.; Schmidt, Raleigh; Mandernack, Kevin W.

    2013-01-01

    Seepage of coal-bed methane (CBM) through soils is a potential source of atmospheric CH4 and also a likely source of ancient (i.e. 14C-dead) carbon to soil microbial communities. Natural abundance 13C and 14C compositions of bacterial membrane phospholipid fatty acids (PLFAs) and soil gas CO2 and CH4 were used to assess the incorporation of CBM-derived carbon into methanotrophs and other members of the soil microbial community. Concentrations of type I and type II methanotroph PLFA biomarkers (16:1ω8c and 18:1ω8c, respectively) were elevated in CBM-impacted soils compared with a control site. Comparison of PLFA and 16s rDNA data suggested type I and II methanotroph populations were well estimated and overestimated by their PLFA biomarkers, respectively. The δ13C values of PLFAs common in type I and II methanotrophs were as negative as −67‰ and consistent with the assimilation of CBM. PLFAs more indicative of nonmethanotrophic bacteria had δ13C values that were intermediate indicating assimilation of both plant- and CBM-derived carbon. Δ14C values of select PLFAs (−351 to −936‰) indicated similar patterns of CBM assimilation by methanotrophs and nonmethanotrophs and were used to estimate that 35–91% of carbon assimilated by nonmethanotrophs was derived from CBM depending on time of sampling and soil depth.

  5. Colloidal stability of coal-simulated suspensions in selective agglomeration

    SciTech Connect

    Schurger, M.L.

    1989-01-01

    A coal suspension was simulated by using graphite to simulate the carbonaceous fraction and kaolinite clay to simulate the ash fraction. Separate studies on each material established their response to additions of oxidized pyrite (ferrous sulfate) and a humic acid simulate (salicylic acid) in terms of zeta potentials profiles with pH and Ionic strength. Concentrations of iron and salicylic acid evaluated were 4.5 {times} 10{sup {minus}3} M and 2.0 {times} 10{sup {minus}4} M, respectively. The zeta potentials profiles of graphite, clay and hexadecane were negative throughout the pH ranges studied. The addition of iron lowered the zeta potentials all of the suspensions under all pH and ionic strength conditions. Salicylic acid decreased the graphite and hexadecane zeta potentials but had no effect on the clay zeta potential profiles. Agglomeration of graphite with bridging liquid shows distinct time dependent rate mechanisms, a initial growth of graphite agglomerates followed by consolidation phase. Graphite agglomeration was rapid with the maximum amount of agglomerate volume growth occurring in under 2-4 minutes. Agglomeration in the first two minutes was characterized by a 1st order rate mechanism. The presence of either Iron and salicylic acid generally improved the first order rates. The addition of clay also improved the first order rates except in the presence of salicylic acid. Heteroagglomeration of graphite with clay was found by hydrodynamic arguments to be unfavored. A multicomponent population balance model which had been developed for evaluating collision efficiencies of coal, ash and pyrite selective agglomeration was evaluated to explain these results. The growth and consolidation characteristics of graphite agglomeration for the experimental conditions examined herein revealed the limitations of such as model for this application.

  6. Novel Binders and Methods for Agglomeration of Ore

    SciTech Connect

    S. K. Kawatra; T. C. Eisele; K. A. Lewandowski; J. A. Gurtler

    2006-12-31

    Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily. Primary examples of this are copper heap leaching, where there are no binders that will work in the acidic environment encountered in this process, and advanced ironmaking processes, where binders must function satisfactorily over an extraordinarily large range of temperatures (from room temperature up to over 1200 C). As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching and advanced primary ironmaking. This project has identified several acid-resistant binders and agglomeration procedures that can be used for improving the energy efficiency of heap leaching, by preventing the ''ponding'' and ''channeling'' effects that currently cause reduced recovery and extended leaching cycle times. Methods have also been developed for iron ore processing which are intended to improve the

  7. Basic principles and mechanisms of selective oil agglomeration. Fossil energy interim report, October 1, 1983--September 30, 1992

    SciTech Connect

    Wheelock, T.D.

    1992-12-31

    Numerous agglomeration tests were conducted with several types of low-ash coal and graphite, high grade mineral pyrite, and other materials. Relatively pure hydrocarbons, including heptane and hexadecane, were used as agglomerants. Access of air to the system was controlled. Particle recovery by agglomeration was observed to depend on a number of system parameters. Among the most important parameters are the hydrophobicity of the particles and the oil dosage, so that the, recovery of solids per unit of oil administered is proportional to the hydrophobicity. The pH and ionic strength of the aqueous suspension affect particle recovery in different ways depending on the surface properties of the particles. On the other hand, the presence of air in the system generally improves particle recovery. The greatest effect of air was observed in a closely related study which showed that air had to be present to produce good agglomerates from a moderately hydrophobic coal in a mixer producing a lower shear rate. The rate of agglomeration was found to be much greater for a strongly hydrophobic coal than for a moderately hydrophobic coal, and the rate was observed to be proportional to the oil dosage. Also the rate was enhanced by the presence of air in the, system. For hydrophobic coals, the rate increased with increasing ionic strength of the aqueous medium, but it was not affected greatly by pH over a wide range. The separation of coal and pyrite particles by selective agglomeration was found to depend on the relative hydrophobicity of the materials, the oil dosage, and the properties of the aqueous medium.

  8. Multivariate analysis applied to agglomerated macrobenthic data from an unpolluted estuary.

    PubMed

    Conde, Anxo; Novais, Júlio M; Domínguez, Jorge

    2013-01-01

    We agglomerated species into higher taxonomic aggregations and functional groups to analyse environmental gradients in an unpolluted estuary. We then applied non-metric Multidimensional Scaling and Redundancy Analysis (RDA) for ordination of the agglomerated data matrices. The correlation between the ordinations produced by both methods was generally high. However, the performance of the RDA models depended on the data matrix used to fit the model. As a result, salinity and total nitrogen were only found significant when aggregated data matrices were used rather than species data matrix. We used the results to select a RDA model that explained a higher percentage of variance in the species data set than the parsimonious model. We conclude that the use of aggregated matrices may be considered complementary to the use of species data to obtain a broader insight into the distribution of macrobenthic assemblages in relation to environmental gradients. PMID:23684322

  9. The impact of solution agglomeration on the deposition of self-assembled monolayers

    SciTech Connect

    BUNKER,BRUCE C.; CARPICK,ROBERT W.; ASSINK,ROGER A.; THOMAS,MICHAEL L.; HANKINS,MATTHEW G.; VOIGT,JAMES A.; SIPOLA,DIANA L.; DE BOER,MAARTEN P.; GULLEY,GERALD L.

    2000-04-17

    Self-assembled monolayers (SAMS) are commonly produced by immersing substrates in organic solutions containing trichlorosilane coupling agents. Unfortunately, such deposition solutions can also form alternate structures including inverse micelles and lamellar phases. The formation of alternate phases is one reason for the sensitivity of SAM depositions to factors such as the water content of the deposition solvent. If such phases are present, the performance of thin films used for applications such as minimization of friction and stiction in micromachines can be seriously compromised. Inverse micelle formation has been studied in detail for depositions involve 1H-, 1H-, 2H-, 2H-perfluorodecyltrichlorosilane (FDTS) in isooctane. Nuclear magnetic resonance experiments have been used to monitor the kinetics of hydrolysis and condensation reactions between water and FDTS. Light scattering experiments show that when hydrolyzed FDTS concentrations reach a critical concentration, there is a burst of nucleation to form high concentrations of spherical agglomerates. Atomic force microscopy results show that the agglomerates then deposit on substrate surfaces. Deposition conditions leading to monolayer formation involve using deposition times that are short relative to the induction time for agglomeration. After deposition, inverse micelles can be converted into lamellar or monolayer structures with appropriate heat treatments if surface concentrations are relatively low.

  10. Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

    NASA Astrophysics Data System (ADS)

    Schneider, P.; Lahoz, W. A.; van der A, R.

    2014-09-01

    Trends in tropospheric nitrogen dioxide (NO2) concentrations over 66 large urban agglomerations worldwide have been computed using data from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument onboard the Envisat platform for the period August 2002 to March 2012. A seasonal model including a linear trend was fitted to the satellite-based time series over each site. The results indicate distinct spatial patterns in trends. While agglomerations in Europe, North America, and some locations in East Asia/Oceania show decreasing tropospheric NO2 levels on the order of -5 % yr-1, rapidly increasing levels of tropospheric NO2 are found for agglomerations in large parts of Asia, Africa, and South America. The site with the most rapidly increasing absolute levels of tropospheric NO2 was found to be Tianjin in China with a trend value of 3.04 (±0.47) × 1015 molecules cm-2 yr-1, whereas the site with the most rapidly increasing relative trend was Kabul in Afghanistan with 14.3 (±2.2) % yr-1. In total, 34 sites exhibited increasing trends of tropospheric NO2 throughout the study period, 24 of which were found to be statistically significant. A total of 32 sites showed decreasing levels of tropospheric NO2 during the study period, of which 20 sites did so at statistically significant magnitudes. Overall, going beyond the relatively small set of megacities investigated previously, this study provides the first consistent analysis of recent changes in tropospheric NO2 levels over most large urban agglomerations worldwide.

  11. Recent satellite-based trends of tropospheric nitrogen dioxide over large urban agglomerations worldwide

    NASA Astrophysics Data System (ADS)

    Schneider, P.; Lahoz, W. A.; van der A, R.

    2015-02-01

    Trends in tropospheric nitrogen dioxide (NO2) columns over 66 large urban agglomerations worldwide have been computed using data from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument onboard the Envisat platform for the period August 2002 to March 2012. A seasonal model including a~linear trend was fitted to the satellite-based time series over each site. The results indicate distinct spatial patterns in trends. While agglomerations in Europe, North America, and some locations in East Asia/Oceania show decreasing tropospheric NO2 levels on the order of -5% yr-1, rapidly increasing levels of tropospheric NO2 are found for agglomerations in large parts of Asia, Africa, and South America. The site with the most rapidly increasing absolute levels of tropospheric NO2 was found to be Tianjin in China with a trend of 3.04 (±0.47) × 1015 molecules cm-2yr-1, whereas the site with the most rapidly increasing relative trend was Kabul in Afghanistan with 14.3 (±2.2) % yr-1. In total, 34 sites exhibited increasing trends of tropospheric NO2 throughout the study period, 24 of which were found to be statistically significant. A total of 32 sites showed decreasing levels of tropospheric NO2 during the study period, of which 20 sites did so at statistically significant magnitudes. Overall, going beyond the relatively small set of megacities investigated previously, this study provides the first consistent analysis of recent changes in tropospheric NO2 levels over most large urban agglomerations worldwide, and indicates that changes in urban NO2 levels are subject to substantial regional differences as well as influenced by economic and demographic factors.

  12. Advanced physical fine coal cleaning spherical agglomeration. Final report

    SciTech Connect

    Not Available

    1990-09-01

    The project included process development, engineering, construction, and operation of a 1/3 tph proof-of-concept (POC) spherical agglomeration test module. The POC tests demonstrated that physical cleaning of ultrafine coal by agglomeration using heptane can achieve: (1) Pyritic sulfur reductions beyond that possible with conventional coal cleaning methods; (2) coal ash contents below those which can be obtained by conventional coal cleaning methods at comparable energy recoveries; (3) energy recoveries of 80 percent or greater measured against the raw coal energy content; (4) complete recovery of the heptane bridging liquid from the agglomerates; and (5) production of agglomerates with 3/8-inch size and less than 30 percent moisture. Test results met or exceeded all of the program objectives. Nominal 3/8-inch size agglomerates with less than 20 percent moisture were produced. The clean coal ash content varied between 1.5 to 5.5 percent by weight (dry basis) depending on feed coal type. Ash reductions of the run-of-mine (ROM) coal were 77 to 83 percent. ROM pyritic sulfur reductions varied from 86 to 90 percent for the three test coals, equating to total sulfur reductions of 47 to 72 percent.

  13. A Critical Study of Agglomerated Multigrid Methods for Diffusion

    NASA Technical Reports Server (NTRS)

    Nishikawa, Hiroaki; Diskin, Boris; Thomas, James L.

    2011-01-01

    Agglomerated multigrid techniques used in unstructured-grid methods are studied critically for a model problem representative of laminar diffusion in the incompressible limit. The studied target-grid discretizations and discretizations used on agglomerated grids are typical of current node-centered formulations. Agglomerated multigrid convergence rates are presented using a range of two- and three-dimensional randomly perturbed unstructured grids for simple geometries with isotropic and stretched grids. Two agglomeration techniques are used within an overall topology-preserving agglomeration framework. The results show that multigrid with an inconsistent coarse-grid scheme using only the edge terms (also referred to in the literature as a thin-layer formulation) provides considerable speedup over single-grid methods but its convergence deteriorates on finer grids. Multigrid with a Galerkin coarse-grid discretization using piecewise-constant prolongation and a heuristic correction factor is slower and also grid-dependent. In contrast, grid-independent convergence rates are demonstrated for multigrid with consistent coarse-grid discretizations. Convergence rates of multigrid cycles are verified with quantitative analysis methods in which parts of the two-grid cycle are replaced by their idealized counterparts.

  14. Theranostic potential of gold nanoparticle-protein agglomerates.

    PubMed

    Sanpui, Pallab; Paul, Anumita; Chattopadhyay, Arun

    2015-11-28

    Owing to the ever-increasing applications, glittered with astonishing success of gold nanoparticles (Au NPs) in biomedical research as diagnostic and therapeutic agents, the study of Au NP-protein interaction seems critical for maximizing their theranostic efficiency, and thus demands comprehensive understanding. The mutual interaction of Au NPs and proteins at physiological conditions may result in the aggregation of protein, which can ultimately lead to the formation of Au NP-protein agglomerates. In the present article, we try to appreciate the plausible steps involved in the Au NP-induced aggregation of proteins and also the importance of the proteins' three-dimensional structures in the process. The Au NP-protein agglomerates can potentially be exploited for efficient loading and subsequent release of various therapeutically important molecules, including anticancer drugs, with the unique opportunity of incorporating hydrophilic as well as hydrophobic drugs in the same nanocarrier system. Moreover, the Au NP-protein agglomerates can act as 'self-diagnostic' systems, allowing investigation of the conformational state of the associated protein(s) as well as the protein-protein or protein-Au NP interaction within the agglomerates. Furthermore, the potential of these Au NP-protein agglomerates as a novel platform for multifunctional theranostic application along with exciting future-possibilities is highlighted here. PMID:26508277

  15. A Critical Study of Agglomerated Multigrid Methods for Diffusion

    NASA Technical Reports Server (NTRS)

    Thomas, James L.; Nishikawa, Hiroaki; Diskin, Boris

    2009-01-01

    Agglomerated multigrid techniques used in unstructured-grid methods are studied critically for a model problem representative of laminar diffusion in the incompressible limit. The studied target-grid discretizations and discretizations used on agglomerated grids are typical of current node-centered formulations. Agglomerated multigrid convergence rates are presented using a range of two- and three-dimensional randomly perturbed unstructured grids for simple geometries with isotropic and highly stretched grids. Two agglomeration techniques are used within an overall topology-preserving agglomeration framework. The results show that multigrid with an inconsistent coarse-grid scheme using only the edge terms (also referred to in the literature as a thin-layer formulation) provides considerable speedup over single-grid methods but its convergence deteriorates on finer grids. Multigrid with a Galerkin coarse-grid discretization using piecewise-constant prolongation and a heuristic correction factor is slower and also grid-dependent. In contrast, grid-independent convergence rates are demonstrated for multigrid with consistent coarse-grid discretizations. Actual cycle results are verified using quantitative analysis methods in which parts of the cycle are replaced by their idealized counterparts.

  16. Theranostic potential of gold nanoparticle-protein agglomerates

    NASA Astrophysics Data System (ADS)

    Sanpui, Pallab; Paul, Anumita; Chattopadhyay, Arun

    2015-11-01

    Owing to the ever-increasing applications, glittered with astonishing success of gold nanoparticles (Au NPs) in biomedical research as diagnostic and therapeutic agents, the study of Au NP-protein interaction seems critical for maximizing their theranostic efficiency, and thus demands comprehensive understanding. The mutual interaction of Au NPs and proteins at physiological conditions may result in the aggregation of protein, which can ultimately lead to the formation of Au NP-protein agglomerates. In the present article, we try to appreciate the plausible steps involved in the Au NP-induced aggregation of proteins and also the importance of the proteins' three-dimensional structures in the process. The Au NP-protein agglomerates can potentially be exploited for efficient loading and subsequent release of various therapeutically important molecules, including anticancer drugs, with the unique opportunity of incorporating hydrophilic as well as hydrophobic drugs in the same nanocarrier system. Moreover, the Au NP-protein agglomerates can act as `self-diagnostic' systems, allowing investigation of the conformational state of the associated protein(s) as well as the protein-protein or protein-Au NP interaction within the agglomerates. Furthermore, the potential of these Au NP-protein agglomerates as a novel platform for multifunctional theranostic application along with exciting future-possibilities is highlighted here.

  17. Variability of bed drag on cohesive beds under wave action

    USGS Publications Warehouse

    Safak, Ilgar

    2016-01-01

    Drag force at the bed acting on water flow is a major control on water circulation and sediment transport. Bed drag has been thoroughly studied in sandy waters, but less so in muddy coastal waters. The variation of bed drag on a muddy shelf is investigated here using field observations of currents, waves, and sediment concentration collected during moderate wind and wave events. To estimate bottom shear stress and the bed drag coefficient, an indirect empirical method of logarithmic fitting to current velocity profiles (log-law), a bottom boundary layer model for combined wave-current flow, and a direct method that uses turbulent fluctuations of velocity are used. The overestimation by the log-law is significantly reduced by taking turbulence suppression due to sediment-induced stratification into account. The best agreement between the model and the direct estimates is obtained by using a hydraulic roughness of 10  m in the model. Direct estimate of bed drag on the muddy bed is found to have a decreasing trend with increasing current speed, and is estimated to be around 0.0025 in conditions where wave-induced flow is relatively weak. Bed drag shows an increase (up to fourfold) with increasing wave energy. These findings can be used to test the bed drag parameterizations in hydrodynamic and sediment transport models and the skills of these models in predicting flows in muddy environments.

  18. Apparatus, components and operating methods for circulating fluidized bed transport gasifiers and reactors

    DOEpatents

    Vimalchand, Pannalal; Liu, Guohai; Peng, Wan Wang

    2015-02-24

    The improvements proposed in this invention provide a reliable apparatus and method to gasify low rank coals in a class of pressurized circulating fluidized bed reactors termed "transport gasifier." The embodiments overcome a number of operability and reliability problems with existing gasifiers. The systems and methods address issues related to distribution of gasification agent without the use of internals, management of heat release to avoid any agglomeration and clinker formation, specific design of bends to withstand the highly erosive environment due to high solid particles circulation rates, design of a standpipe cyclone to withstand high temperature gasification environment, compact design of seal-leg that can handle high mass solids flux, design of nozzles that eliminate plugging, uniform aeration of large diameter Standpipe, oxidant injection at the cyclone exits to effectively modulate gasifier exit temperature and reduction in overall height of the gasifier with a modified non-mechanical valve.

  19. The fate of Salicaceae seedlings related to the dynamics of alluvial bars during floods: differentiating bed erosion, uprooting and burying.

    NASA Astrophysics Data System (ADS)

    Wintenberger, C. L.; Rodrigues, S.; Bréhéret, J. G.; Juge, P.; Villar, M.

    2014-12-01

    available bed shear stress and sediment size. Then the deposit occurs on the back of the bar before the peak discharge and protects them against uprooting by burying during the higher energy of flow. At the end of the falling limb, sediments are reworked, decreasing the burying height of seedlings and allowing possible uprooting (drag) or erosion of sediments.

  20. Relative Biologic Effectiveness (RBE) of 50 kV X-rays Measured in a Phantom for Intraoperative Tumor-Bed Irradiation

    SciTech Connect

    Liu, Qi; Schneider, Frank; Ma, Lin; Wenz, Frederik; Herskind, Carsten

    2013-03-15

    Purpose: Intraoperative radiation therapy (IORT) with low-energy x-rays is used to treat the tumor bed during breast-conserving surgery. The purpose was to determine the relative biologic effectiveness (RBE) of 50-kV x-rays for inactivation of cells irradiated in a tumor-bed phantom. Methods and Materials: The RBE was determined for clonogenic inactivation of human tumor and normal cells (MCF7, human umbilical vein endothelial cells, normal skin fibroblasts), and hamster V79 cells. The 50-kV x-rays from the Intrabeam machine (Carl Zeiss Surgical) with a spherical 4-cm applicator were used. Cells were irradiated in a water-equivalent phantom at defined distances (8.1-22.9 mm) from the applicator surface. The 50-kV x-rays from a surface therapy machine (Dermopan, Siemens) were included for comparison; 6-MV x-rays were used as reference radiation. Results: At 8.1-mm depth in the phantom (dose rate 15.1 Gy/h), mean RBE values of 50-kV x-rays from Intrabeam were 1.26 to 1.42 for the 4 cell types at doses yielding surviving fractions in the range of 0.01 to 0.5. Confidence intervals were in the range of 1.2 and 1.5. Similar RBE values were found for 50-kV x-rays from Dermopan for V79 (1.30, CI 1.25-1.36, P=.74) and GS4 (1.42, CI 1.30-1.54, P=.67). No significant dependence of RBE on dose was found for Intrabeam, but RBE decreased at a larger distance (12.7 mm; 9.8 Gy/h). Conclusions: An increased clinically relevant RBE was found for cell irradiation with Intrabeam at depths in the tumor bed targeted by IORT. The reduced RBE values at larger distances may be related to increased repair of sublethal damage during protracted irradiation or to hardening of the photon beam energy.

  1. Basic principles and mechanisms of selective oil agglomeration

    SciTech Connect

    Wheelock, T.D.; Drzymala, J.; Allen, R.W.; Hu, Y.-C.; Tyson, D.; Xiaoping, Qiu; Lessa, A.

    1990-01-01

    Numerous measurements of the heat of immersion of coal were conducting using several different particle size fractions of No. 2 Gas Seam coal from Raleigh County, West Virginia. The heat of immersion was determined in water, methanol, heptane, hexadecane and neohexane (2,2-dimethybutane). A comparison of the results with those determined previously for Illinois No. 6 coal is discussed. A number of potential pyrite depressants for use in oil agglomeration of coal were screened by testing the response of sulfidized mineral pyrite to agglomeration with heptane in the presence of the potential depressant. The following were tested; sodium dithionite, sodium thiosulfate, ferrous sulfate, ferric sulfate, titanous chloride, hydrogen peroxide, Oxone (a form of potassium monopersulfate), pyrogallol, quebracho (colloidal dispersant derived from tree bark), milk whey, and several organic thiols. Ferric chloride was applied to mixtures of Upper Freeport coal and sulfidized mineral pyrite before subjecting the mixtures to agglomeration with heptane. 7 refs., 23 figs., 3 tabs.

  2. Ultrasonic de-agglomeration of barium titanate powder.

    PubMed

    Marković, S; Mitrić, M; Starcević, G; Uskoković, D

    2008-01-01

    BaTiO3 (BT) powder, with average particle size of 1.4 microm, was synthesized by solid-state reaction. A high-intensity ultrasound irradiation (ultrasonication) was used to de-agglomerate micro-sized powder to nano-sized one. The crystal structure, crystallite size, morphology, particle size, particle size distribution, and specific surface area of the BT powder de-agglomerated for different ultrasonication times (0, 10, 60, and 180 min) were determined. It was found that the particles size of the BT powder was influenced by ultrasonic treatment, while its tetragonal structure was maintained. Therefore, ultrasonic irradiation can be proposed as an environmental-friendly, economical, and effective tool for the de-agglomeration of barium titanate powders. PMID:17845864

  3. Effect of calcium ions on agglomeration of bayer aluminium trihydroxide

    NASA Astrophysics Data System (ADS)

    Brown, N.

    1988-10-01

    Small amounts of calcium ions in caustic aluminate solution can lead to enhanced agglomeration of aluminium trihydroxide [Al(OH) 3] particles in the crystallization step of the Bayer process. The present study shows that the magnitude of the effect is strongly dependent on the nature and polycrystallinity of the Al(OH) 3 seed crystals. The more irregular and polycrystalline the seed crystals, the smaller is the optimum amount of added calcium for maximum coarsening ( ≈ 50 mg/l, expressed as CaO). While the same degree of agglomeration can be achieved using well-rounded, smooth-surfaced seed crystals of the same overall size, more calcium is required (75-100 mg/l, expressed as CaO) and the agglomerated particles formed are weaker and less resistant to size reduction on handling.

  4. Quantum dot agglomerates in biological media and their characterization by asymmetrical flow field-flow fractionation.

    PubMed

    Moquin, Alexandre; Neibert, Kevin D; Maysinger, Dusica; Winnik, Françoise M

    2015-01-01

    The molecular composition of the biological environment of nanoparticles influences their physical properties and changes their pristine physicochemical identity. In order to understand, or predict, the interactions of cells with specific nanoparticles, it is critical to know their size, shape, and agglomeration state not only in their nascent state but also in biological media. Here, we use asymmetrical flow field-flow fractionation (AF4) with on-line multiangle light scattering (MALS), dynamic light scattering (DLS) and UV-Visible absorption detections to determine the relative concentration of isolated nanoparticles and agglomerates in the case of three types of semi-conductor quantum dots (QDs) dispersed in Dulbecco's Modified Eagle Media (DMEM) containing 10% of fetal bovine serum (DMEM-FBS). AF4 analysis also yielded the size and size distribution of the agglomerates as a function of the time of QDs incubation in DMEM-FBS. The preferred modes of internalization of the QDs are assessed for three cell-types, N9 microglia, human hepatocellular carcinoma cells (HepG2) and human embryonic kidney cells (Hek293), by confocal fluorescence imaging of live cells, quantitative determination of the intracellular QD concentration, and flow cytometry. There is an excellent correlation between the agglomeration status of the three types of QDs in DMEM-FBS determined by AF4 analysis and their preferred mode of uptake by the three cell lines, which suggests that AF4 yields an accurate description of the nanoparticles as they encounter cells and advocates its use as a means to characterize particles under evaluation. PMID:25542679

  5. Continuous air Agglomeration Method for high Carbon fly ash Beneficiation

    SciTech Connect

    Gray, McMahan L.; Champagne, Kenneth J.; Finseth, Dennis H.

    1998-09-29

    The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carbon-free mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

  6. Element Agglomeration Algebraic Multilevel Monte-Carlo Library

    SciTech Connect

    2015-02-19

    ElagMC is a parallel C++ library for Multilevel Monte Carlo simulations with algebraically constructed coarse spaces. ElagMC enables Multilevel variance reduction techniques in the context of general unstructured meshes by using the specialized element-based agglomeration techniques implemented in ELAG (the Element-Agglomeration Algebraic Multigrid and Upscaling Library developed by U. Villa and P. Vassilevski and currently under review for public release). The ElabMC library can support different type of deterministic problems, including mixed finite element discretizations of subsurface flow problems.

  7. A pocket model for aluminum agglomeration in composite propellants

    NASA Technical Reports Server (NTRS)

    Cohen, N. S.

    1981-01-01

    This paper presents a model for the purpose of estimating the fraction of aluminum powder that will form agglomerates at the surface of deflagrating composite propellants. The basic idea is that the fraction agglomerated depends upon the amount of aluminum that melts within effective binder pocket volumes framed by oxidizer particles. The effective pocket depends upon the ability of ammonium perchlorate modals to encapsulate the aluminum and provide a local temperature sufficient to ignite the aluminum. Model results are discussed in the light of data showing effects of propellant formulation variables and pressure.

  8. Agglomeration behavior of solid nickel on polycrystalline barium titanate

    SciTech Connect

    Weil, K Scott; Mast, Eric S; Sprenkle, Vince

    2007-11-01

    This letter describes the phenomenon that takes place between nickel/barium titanate couples when heated under conditions employed in multilayer ceramic capacitor manufacturing practice: a 4hr, 1300°C isothermal anneal in 1% H2 – 99% N2. Dense, sputtered nickel films were observed to dewet the titanate and agglomerate into discrete or interconnected islands via a solid-state process. Up to a critical film thickness value of ~1.4 μm, the degree of agglomeration was found to display an exponential dependence on the thickness of the original nickel film.

  9. Element Agglomeration Algebraic Multilevel Monte-Carlo Library

    Energy Science and Technology Software Center (ESTSC)

    2015-02-19

    ElagMC is a parallel C++ library for Multilevel Monte Carlo simulations with algebraically constructed coarse spaces. ElagMC enables Multilevel variance reduction techniques in the context of general unstructured meshes by using the specialized element-based agglomeration techniques implemented in ELAG (the Element-Agglomeration Algebraic Multigrid and Upscaling Library developed by U. Villa and P. Vassilevski and currently under review for public release). The ElabMC library can support different type of deterministic problems, including mixed finite element discretizationsmore » of subsurface flow problems.« less

  10. Continuous air agglomeration method for high carbon fly ash beneficiation

    DOEpatents

    Gray, McMahon L.; Champagne, Kenneth J.; Finseth, Dennis H.

    2000-01-01

    The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carboree mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

  11. STATISTICAL COMPARISON OF THE EFFECT OF RELATIVE AND ABSOLUTE HUMIDITY ON FIXED-BED CARBON ADSORPTION CAPACITY

    EPA Science Inventory

    The paper describes statistical methods used to evaluate data for toluene (at several typical operating temperatures and humidity levels) and to determine which measure of humidity (relative or absolute) is more important in determining carbon adsorption efficiency. The water con...

  12. Facies And Bedding Analysis of Deep-Marine, Arc-Related, Sediementary Rocks Cored on International Ocean Drilling Program Expedition 351.

    NASA Astrophysics Data System (ADS)

    Johnson, K. E.; Marsaglia, K. M.

    2015-12-01

    The Izu-Bonin-Mariana (IBM) Arc System, south of Japan, hosts a multitude of active and extinct (remnant) arc volcanic sediment sources. Core extracted adjacent to the proto-IBM arc (Kyushu-Palau Ridge; KPR) in the Amami-Sankaku Basin on International Ocean Discovery Program (IODP) Expedition 351 contains evidence of the variety of sediment sources that have existed in the area as a result of changing tectonic regimes through arc development, backarc basin formation and remnant arc abandonment. Approximately 1000 meters of Eocene to Oligocene volcaniclastic sedimentary rocks were analyzed via shipboard core photos, core descriptions, and thin sections with the intention of understanding the depositional history at this site. These materials contain a crucial record of arc development complementary to the Neogene history preserved in the active reararc (Expedition 350) and compressed whole-arc record in the current forearc (Expedition 352). A database of stratigraphic columns was created to display grain size trends, facies changes, and bedding characteristics. Individual beds (depositional events) were classified using existing and slightly modified classification schemes for muddy, sandy and gravel-rich gravity flow deposits, as well as muddy debris flows and tuffs. Utilizing the deep marine facies classes presented by Pickering et al. (1986), up section changes are apparent. Through time, as the arc developed, facies and bedding types and their proportions change dramatically and relatively abruptly. Following arc initiation facies are primarily mud-rich with intercalated tuffaceous sand. In younger intervals, sand to gravel gravity-flow deposits dominate, becoming more mud-rich. Muddy gravity flow deposits, however, dominate farther upsection. The overall coarsening-upward pattern (Unit III) is consistent with building of the arc edifice. Farther upsection (Unit II) an abrupt fining-upward trend represents the onset of isolation of the KPR as backarc spreading

  13. Rapid nitric oxide- and prostaglandin-dependent release of calcitonin gene-related peptide (CGRP) triggered by endotoxin in rat mesenteric arterial bed.

    PubMed Central

    Wang, X.; Wu, Z.; Tang, Y.; Fiscus, R. R.; Han, C.

    1996-01-01

    1. Our objective was to determine whether endotoxin (ETX) could directly trigger the release of calcitonin gene-related peptide (CGRP) from perivascular sensory nerves in the isolated mesenteric arterial bed (MAB) of the rat and to determine whether nitric oxide (NO) and prostaglandins (PGs) are involved. 2. ETX caused time- and concentration-dependent release of CGRP, and as much as a 17 fold increase in CGRP levels in the perfusate at 10-15 min after the administration of ETX (50 micrograms ml-1). 3. CGRP-like immunoreactivity in the perfusate was shown to co-elute with synthetic rat CGRP by reverse-phase h.p.l.c. 4. Pretreatment of MAB with capsaicin or ruthenium red inhibited ETX-induced CGRP release by 90% and 71%, respectively. ETX-evoked CGRP release was decreased by 84% during Ca2(+)-free perfusion. 5. The release of CGRP evoked by ETX was enhanced by L-arginine by 43% and inhibited by N omega-nitro-L-arginine (L-NOARG) and methylene blue by 37% and 38%, respectively. L-Arginine reversed the effect of L-NOARG. 6. Indomethacin and ibuprofen also inhibited the ETX-induced CGRP release by 34% and 44%, respectively. No additive inhibition could be found when L-NOARG and indomethacin were concomitantly incubated. 7. The data suggest that ETX triggers the release of CGRP from capsaicin-sensitive sensory nerves innervating blood vessels. The ETX-induced CGRP release is dependent on extracellular Ca2+ influx and involves a ruthenium red-sensitive mechanism. Both NO and PGs appear to be involved in the ETX-induced release of CGRP in the rat mesenteric arterial bed. PMID:8864557

  14. 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 ...

  15. Frequency comparative study of coal-fired fly ash acoustic agglomeration.

    PubMed

    Liu, Jianzhong; Wang, Jie; Zhang, Guangxue; Zhou, Junhu; Cen, Kefa

    2011-01-01

    Particulate pollution is main kind of atmospheric pollution. The fine particles are seriously harmful to human health and environment. Acoustic agglomeration is considered as a promising pretreatment technology for fine particle agglomeration. The mechanisms of acoustic agglomeration are very complex and the agglomeration efficiency is affected by many factors. The most important and controversial factor is frequency. Comparative studies between high-frequency and low-frequency sound source to agglomerate coal-fired fly ash were carried out to investigate the influence of frequency on agglomeration efficiency. Acoustic agglomeration theoretical analysis, experimental particle size distributions (PSDs) and orthogonal design were examined. The results showed that the 20 kHz high-frequency sound source was not suitable to agglomerate coal-fired fly ash. Only within the size ranging from 0.2 to 0.25 microm the particles agglomerated to adhere together, and the agglomerated particles were smaller than 2.5 microm. The application of low-frequency (1000-1800 Hz) sound source was proved as an advisable pretreatment with the highest agglomeration efficiency of 75.3%, and all the number concentrations within the measuring range decreased. Orthogonal design L16 (4)3 was introduced to determine the optimum frequency and optimize acoustic agglomeration condition. According to the results of orthogonal analysis, frequency was the dominant factor of coal-fired fly ash acoustic agglomeration and the optimum frequency was 1400 Hz. PMID:22432309

  16. Basic principles and mechanisms of selective oil agglomeration

    SciTech Connect

    Wheelock, T.D.; Drzymala, J.; Allen, R.W.; Hu, Y.C.; Tyson, D.; Ziaoping, Qiu, Lessa, A.

    1990-04-01

    The overall objective is to determine the basic principles and mechanisms which underlie a number of selective oil agglomeration processes that have been proposed for beneficiating fine-size coal. An understanding of the basic principles and mechanisms will greatly facilitate technical development and application of such processes to various types of coal. 5 refs., 16 figs., 2 tabs.

  17. Universities' Entrepreneurial Performance: The Role of Agglomeration Economies

    ERIC Educational Resources Information Center

    Chen, Ping Penny

    2011-01-01

    In spite of the extensive research on universities' entrepreneurship, whether research strength fosters or dampens their entrepreneurial performance remains controversial. Much research claims an influential role of research universities in regional economy, however, little has been said about what a part that the agglomeration economies may play…

  18. Engineering development of selective agglomeration. Site closeout report

    SciTech Connect

    Not Available

    1993-04-01

    The Selective Agglomeration POC facility consisted of a coal crushing and grinding circuit, followed by an agglomeration circuit and product dewatering. (A plot plan of the facility is shown in Figure 1-2.) The coal crushing and grinding system consisted of a hammermill coal crusher, weigh-belt feeder, two ball mills (primary and secondary), and necessary hoppers, pumps, and conveyors. The mills were capable of providing coal over a range of grinds from a d{sub 50} of 125 to 25 microns. Slurry discharged from the ball mills was pumped to the agglomeration circuit. The agglomeration circuit began with a high-shear mixer, where diesel was added to the slurry to begin the formation of microagglomerates. The high-shear mixer was followed by two stages of conventional flotation cells for microagglomerate recovery. The second-stage-flotation-cell product was pumped to either a rotary-drum vacuum filter or a high-G centrifuge for dewatering. The dewatered product was then convoyed to the product pad from which dump trucks were used to transfer it to the utility plant located next to the facility. Plant tailings were pumped to the water clarifier for thickening and then dewatered in plate-and-frame filter presses. These dewatered tailings were also removed to the utility via dump truck. Clarified water (thickener overflow) was recycled to the process via a head tank.

  19. Experimental study on static and impact strength of sintered agglomerates

    NASA Astrophysics Data System (ADS)

    Machii, Nagisa; Nakamura, Akiko M.

    2011-01-01

    Porous internal structure is common among small bodies in the planetary systems and possible range of porosity, strength, and scale of in-homogeneity is wide. Icy agglomerates, such as icy dust aggregates in the proto-planetary disks or icy re-accumulated bodies of fragments from impact disruption beyond snow-line would have stronger bulk strength once the component particles physically connect each other due to sintering. In this study, in order to get better understanding of impact disruption process of such bodies, we first investigated the critical tensile (normal) and bending (tangential) forces to break a single neck, the connected part of the sintered particles, using sintered dimer of macro glass particles of ˜5 mm in diameter. We found that the critical tensile force is proportional to the cross-section of the neck when the neck grows sufficiently larger than the surface roughness of the original particles. We also found that smaller force is required to break a neck when the force is applied tangentially to the neck than normally applied. Then we measured the bulk tensile strength of sintered glass agglomerates consisting of 90 particles and showed that the average tensile stress to break a neck of agglomerates in static loading is consistent with the measured value for dimers. Impact experiments with velocity from 40 to 280 m/s were performed for the sintered agglomerates with ˜40% porosity, of two different bulk tensile strengths. The size ratio of the beads to the target was 0.19. The energy density required to catastrophically break the agglomerate was shown to be much less than those required for previously investigated sintered glass beads targets with ˜40% porosity, of which the size of component bead is 10 -2 times smaller and the size ratio of the bead to target is also ˜10 -2 times smaller than the agglomerates in this study. This is probably due to much smaller number of necks for the stress wave to travel through the agglomerates and

  20. Clinical skills: bed making and patient positioning.

    PubMed

    Pellatt, Glynis Collis

    Providing a clean, comfortable bed and positioning a patient in the optimum posture for prevention of complications and to enable maximum independence are fundamental nursing skills. Bed-making is a daily routine that requires practical and technical skills. Selecting the correct posture for a patient in bed or in a chair is essential for physiological functioning and recovery. In this article bed-making is described, as are positioning and re-positioning in relation to patients in bed, armchairs and wheelchairs. Infection control and moving and handling issues are also considered. PMID:17505378

  1. Earth-moon Lagrangian points as a test bed for general relativity and effective field theories of gravity

    NASA Astrophysics Data System (ADS)

    Battista, Emmanuele; Dell'Agnello, Simone; Esposito, Giampiero; Di Fiore, Luciano; Simo, Jules; Grado, Aniello

    2015-09-01

    We first analyze the restricted four-body problem consisting of the Earth, the Moon, and the Sun as the primaries and a spacecraft as the planetoid. This scheme allows us to take into account the solar perturbation in the description of the motion of a spacecraft in the vicinity of the stable Earth-Moon libration points L4 and L5 both in the classical regime and in the context of effective field theories of gravity. A vehicle initially placed at L4 or L5 will not remain near the respective points. In particular, in the classical case the vehicle moves on a trajectory about the libration points for at least 700 days before escaping. We show that this is true also if the modified long-distance Newtonian potential of effective gravity is employed. We also evaluate the impulse required to cancel out the perturbing force due to the Sun in order to force the spacecraft to stay precisely at L4 or L5. It turns out that this value is slightly modified with respect to the corresponding Newtonian one. In the second part of the paper, we first evaluate the location of all Lagrangian points in the Earth-Moon system within the framework of general relativity. For the points L4 and L5, the corrections of coordinates are of order a few millimeters and describe a tiny departure from the equilateral triangle. After that, we set up a scheme where the theory which is quantum corrected has as its classical counterpart the Einstein theory, instead of the Newtonian one. In other words, we deal with a theory involving quantum corrections to Einstein gravity, rather than to Newtonian gravity. By virtue of the effective-gravity correction to the long-distance form of the potential among two masses, all terms involving the ratio between the gravitational radius of the primary and its separation from the planetoid get modified. Within this framework, for the Lagrangian points of stable equilibrium, we find quantum corrections of order 2 mm, whereas for Lagrangian points of unstable

  2. Prediction of Bed Load Transport on Small Gravel-Bed Streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rates and size distributions of bed load were calculated using 3 transport relations and compared to data collected on three streams with sand-gravel beds in the Goodwin Creek Experimental Watershed in north central Mississippi, USA. Bed load transport rates were greatly over predicted by two of th...

  3. Proceedings of the 19 biennial conference of the institute for briquetting and agglomeration

    SciTech Connect

    Not Available

    1985-01-01

    This book presents the papers given at a conference on the briquetting and agglomeration of materials. Topics considered at the conference included the pelletizing of carbon black, the agglomeration of hard coal, the selection of a coal agglomerate for gasification, the briquetting of soft lignite, fiber addition for increased pellet strength, properties of granules, compaction, the Iowa agglomeration process, land disposal restrictions, the disposal of hazardous materials and industrial wastes, and the compaction of sludges from municipal waste treatment plants.

  4. Computational fluid dynamic modeling of fluidized-bed polymerization reactors

    SciTech Connect

    Rokkam, Ram

    2012-01-01

    Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.

  5. Combined effects of dam removal and past sediment mining on a relatively large lowland sandy gravel bed river (Vienne River, France)

    NASA Astrophysics Data System (ADS)

    Ursache, Ovidiu; Rodrigues, Stephane; Bouchard, Jean-Pierre; Jugé, Philippe; Richard, Nina

    2014-05-01

    Dam removal is of growing interest for the management of sediment fluxes within fluvial basins, morphological evolution and ecological restoration of rivers. If dam removal experiments are now quite well documented for small streams located in the upstream parts of river networks, examples of lowland and relatively large rivers are still scarce. In this study we present a dam removal operation carried out on the Vienne River (France) to restore both sediment and biotic continuity. The Vienne River is 363 km in length. On its middle reaches the average slope is equal to 0.0003 m.m-1 and the average annual discharge is 195 m3.s-1 at the gauging station of Nouâtre. The river is characterized by a sinuous single channel of an average width of 150 m. The sediments are mainly made of a siliceous mixture of sands and gravels and were intensively mined between years 1930 and 1995's. In 1920, a 4 m height dam was built just downstream the confluence between the Vienne and Creuse Rivers triggering a total sediment deposition upstream of 900 000 m3 in 75 years. Hence, in 1998, the removal of the dam increased severely the sediment supply delivered to the Vienne River. The objective of this study is to understand and quantify the fluvial processes and morphological evolution on a reach of 50 km of the Vienne associated with the dam remova and the presence of ancient sand pits located along the riverbed. This study is based on field data collected during 7 surveys performed between 1998 and 2013. This large dataset focuses on bed geometry (detailed bathymetrical surveys), sediment grain size, and bedload fluxes measured using isokinetic samplers. It was combined with a 1D numerical model developed to assess flow dynamics and sediment transport capacity before and after dam removal. Results show that dam removal triggered both headward and progressive (near the dam) erosions and that discharges higher than 100 m3.s-1 were sufficient to erode the sandy sediments trapped by the

  6. THE PHYSICS OF PROTOPLANETESIMAL DUST AGGLOMERATES. VI. EROSION OF LARGE AGGREGATES AS A SOURCE OF MICROMETER-SIZED PARTICLES

    SciTech Connect

    Schraepler, Rainer; Blum, Juergen

    2011-06-20

    Observed protoplanetary disks consist of a large amount of micrometer-sized particles. Dullemond and Dominik pointed out for the first time the difficulty in explaining the strong mid-infrared excess of classical T Tauri stars without any dust-retention mechanisms. Because high relative velocities in between micrometer-sized and macroscopic particles exist in protoplanetary disks, we present experimental results on the erosion of macroscopic agglomerates consisting of micrometer-sized spherical particles via the impact of micrometer-sized particles. We find that after an initial phase, in which an impacting particle erodes up to 10 particles of an agglomerate, the impacting particles compress the agglomerate's surface, which partly passivates the agglomerates against erosion. Due to this effect, the erosion halts for impact velocities up to {approx}30 m s{sup -1} within our error bars. For higher velocities, the erosion is reduced by an order of magnitude. This outcome is explained and confirmed by a numerical model. In a next step, we build an analytical disk model and implement the experimentally found erosive effect. The model shows that erosion is a strong source of micrometer-sized particles in a protoplanetary disk. Finally, we use the stationary solution of this model to explain the amount of micrometer-sized particles in the observational infrared data of Furlan et al.

  7. [Sonic Enhanced Ash Agglomeration and Sulfur Capture]. [Quarterly technical progress report, September 27, 1993--January 2, 1994

    SciTech Connect

    Not Available

    1993-12-31

    A major concern with the utilization of coal in directly fired gas turbines is the control of particulate emissions and reduction of sulfur dioxide, and alkali vapor from combustion of coal, upstream of the gas turbine. The Sonic Enhanced Ash Agglomeration and Sulfur Capture program focuses upon the application of an MTCI proprietary invention (Patent No. 5,197,399) for simultaneously enhancing sulfur capture and particulate agglomeration of the combustor effluent. This application can be adapted as either a ``hot flue gas cleanup`` subsystem for the current concepts for combustor islands or as an alternative primary pulse combustor island in which slagging, sulfur capture, particulate agglomeration and control, and alkali gettering as well as NO{sub x} control processes become an integral part of the pulse combustion process. The goal of the program is to support the DOE mission in developing coal-fired combustion gas turbines. In particular, the MTCI proprietary process for bimodal ash agglomeration and simultaneous sulfur capture will be evaluated and developed. The technology embodiment of the invention provides for the use of standard grind, moderately beneficiated coal and WEM for firing the gas turbine with efficient sulfur capture and particulate emission control upstream of the turbine. The process also accommodates injection of alkali gettering material if necessary. This is aimed at utilization of relatively inexpensive coal fuels, thus realizing the primary benefit being sought by direct firing of coal in such gas turbine systems.

  8. Sustainable sewage solutions for small agglomerations.

    PubMed

    Galvão, A; Matos, J; Rodrigues, J; Heath, P

    2005-01-01

    In a significant number of European countries, the need for providing appropriate treatment for the effluents of small rural communities is still especially relevant. In fact, in countries like Portugal, Spain, and many others, significant amounts of investment will be addressed in the next few years to the construction of small Wastewater Treatment Plants (WWTP). The problems faced when constructing and operating WWTP serving small communities may be relevant when energy and labour costs are relatively high, or when the visual impact on the surrounding areas is especially negative. Sustainable treatment solutions require the selection of appropriate technologies using fewer resources. In this paper, information is presented about sustainability indicators of twenty-one small secondary wastewater treatment plants, including conventional (trickling filters and extended aeration plants) and non-conventional treatment systems (constructed wetlands). The data refer to allocated areas per inhabitant, amounts of concrete per inhabitant, power per inhabitant, and construction and installation costs per inhabitant. The data seem to show that for different reasons, constructed wetlands are promising treatment solutions for application to rural areas in particular because of the relatively low power requirements and relatively low construction costs for served populations below 500 inhabitants. PMID:16477968

  9. ["Non-solvent shock agglomeration"--the technology of a new alternative method for determination of ibuprofen. 6. Stability of s(+)-ibuprofen].

    PubMed

    Möller, T; Korsatko, W

    2000-06-01

    Due to its low melting range approx. 53 degrees C optically pure ibuprofen can be regarded as problematic in a pharmaceutic-technological sense. With regard to the non-solvent shock agglomeration method this means that the process and product temperatures must strictly be kept in the range of 10 K above the melting point of the substance. Higher temperatures can induce degradation of S(+)ibuprofen. During storage under stress conditions (31 degrees C for a period of 18 months) ibuprofen shows extreme stability independent of its optical activity. Racemic ibuprofen is inert to the influence of light; in individual cases optically pure substance containing an increased level of impurities can show slight degradation tendencies. The thermal and photo stability of ibuprofen is independent of the preparation technology. For comparison, conventional, fluid bed granulated, briquetted and from organic solvents especially recrystallised and optically active substances were investigated besides the shock agglomerated substances. PMID:10907254

  10. Population amalgamation and genetic variation: observations on artificially agglomerated tribal populations of Central and South America.

    PubMed

    Chakraborty, R; Smouse, P E; Neel, J V

    1988-11-01

    The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations of Central and South America, analyzing the pooled sample as though it were a single population. Several striking findings emerge. (1) Mean heterozygosity is not sensitive to agglomeration, but the number of different alleles (allele count) is inflated, relative to neutral mutation/drift/equilibrium expectation. (2) The inflation is most serious for rare alleles, especially those which originally occurred as tribally restricted "private" polymorphisms. (3) The degree of inflation is an increasing function of both the number of populations encompassed by the sample and of the genetic divergence among them. (4) Treating an agglomerated population as though it were a panmictic unit of long standing can lead to serious biases in estimates of mutation rates, selection pressures, and effective population sizes. Current DNA studies indicate the presence of numerous genetic variants in human populations. The findings and conclusions of this paper are all fully applicable to the study of genetic variation at the DNA level as well. PMID:3189334

  11. Engineering development of selective agglomeration: Trace element removal study

    SciTech Connect

    Not Available

    1993-09-01

    Southern Company Services, Inc., (SCS) was contracted in 1989 by the US Department of Energy (DOE) to develop a commercially acceptable selective agglomeration technology to enhance the use of high-sulfur coals by 1993. The project scope involved development of a bench-scale process and components, as well as the design, testing, and evaluation of a proof-of-concept (POC) facility. To that end, a two-ton-per-hour facility was constructed and tested near Wilsonville, Alabama. Although it was not the primary focus of the test program, SCS also measured the ability of selective agglomeration to remove trace elements from coal. This document describes the results of that program.

  12. Functionally graded porous scaffolds made of Ti-based agglomerates.

    PubMed

    Nazari, Keivan A; Hilditch, Tim; Dargusch, Matthew S; Nouri, Alireza

    2016-10-01

    Mono- and double-layer porous scaffolds were successfully fabricated using ball-milled agglomerates of Ti and Ti-10Nb-3Mo alloy. For selectively controlling the level of porosity and pore size, the agglomerates were sieved into two different size fractions of 100-300μm and 300-500μm. Compressive mechanical properties were measured on a series of cylindrical sintered compacts with different ratios of solid core diameter to porous layer width. The graded porous scaffolds exhibited stress-strain curves typical for metallic foams with a defined plateau region after yielding. The compressive strengths and elastic moduli ranged from 300 to 700MPa and 14 to 55GPa, respectively, depending on the core diameter and the material used. The obtained properties make these materials suitable for load-bearing implant applications. PMID:27389321

  13. On Some Versions of the Element Agglomeration AMGe Method

    SciTech Connect

    Lashuk, I; Vassilevski, P

    2007-08-09

    The present paper deals with element-based AMG methods that target linear systems of equations coming from finite element discretizations of elliptic PDEs. The individual element information (element matrices and element topology) is the main input to construct the AMG hierarchy. We study a number of variants of the spectral agglomerate element based AMG method. The core of the algorithms relies on element agglomeration utilizing the element topology (built recursively from fine to coarse levels). The actual selection of the coarse degrees of freedom (dofs) is based on solving large number of local eigenvalue problems. Additionally, we investigate strategies for adaptive AMG as well as multigrid cycles that are more expensive than the V-cycle utilizing simple interpolation matrices and nested conjugate gradient (CG) based recursive calls between the levels. The presented algorithms are illustrated with an extensive set of experiments based on a matlab implementation of the methods.

  14. Preventing ash agglomeration during gasification of high-sodium lignite

    SciTech Connect

    Robert S. Dahlin; Johnny R. Dorminey; WanWang Peng; Roxann F. Leonard; Pannalal Vimalchand

    2009-01-15

    Various additives were evaluated to assess their ability to prevent ash agglomeration during the gasification of high-sodium lignite. Additives that showed promise in simple muffle furnace tests included meta-kaolin, vermiculite, two types of silica fume, and one type of bauxite. Additives that were tested and rejected included dolomite, calcite, sand flour, kaolinite, fine kaolin, and calcined bauxite. Based on the muffle furnace test results, the meta-kaolin was selected for a follow-on demonstration in a pilot-scale coal gasifier. Pilot-scale testing showed that the addition of coarse (minus 14-mesh, 920-{mu}m mean size) meta-kaolin at a feed rate roughly equivalent to the ash content of the lignite (10 wt %) successfully prevented agglomeration and deposition problems during gasification of high-sodium lignite at a maximum operating temperature of 927{sup o}C (1700{sup o}F). 13 refs., 24 figs., 1 tab.

  15. Flocculation, hydrophobic agglomeration and filtration of ultrafine coal

    NASA Astrophysics Data System (ADS)

    Yu, Zhimin

    In coal preparation plant circuits, fine coal particles are aggregated either by oil agglomeration or by flocculation. In a new hydrophobic agglomeration process, recently developed hydrophobic latices are utilized. While the selectivity of such aggregation processes determines the beneficiation results, the degree of aggregation has a strong effect on fine coal filtration. The aim of this research was to study the fundamentals and analyze the common grounds for these processes, including the potential effect of the coal surface properties. The selective flocculation tests, in which three types of coal, which differed widely in surface wettability, and three additives (hydrophobic latices, a semi-hydrophobic flocculant and a typical hydrophilic polyelectrolyte) were utilized, showed that coal wettability plays a very important role in selective flocculation. The abstraction of a hydrophobic latex on coal and silica revealed that the latex had a much higher affinity towards hydrophobic coal than to hydrophilic mineral matter. As a result, the UBC-1 hydrophobic latex flocculated only hydrophobic coal particles while the polyelectrolyte (PAM) flocculated all the tested coal samples and minerals, showing no selectivity in the fine coal beneficiation. The oil agglomeration was tested using kerosene emulsified with various surfactants (e.g. cationic, anionic and non-ionic). Surfactants enhance not only oil emulsification, hence reducing oil consumption (down to 0.25--0.5%), but also entirely change the electrokinetic properties of the droplets and affect the interaction energy between oil droplets and coal particles. Consequently, the results found in the course of the experimental work strongly indicate that even oxidized coals can be agglomerated if cationic surfactants are used to emulsify the oil. Oil agglomeration of the Ford-4 ultrafine coal showed that even at extremely low oil consumption (0.25 to 0.5%), a clean coal product with an ash content around 5% at over

  16. Liquid bridge agglomeration: A fundamental approach to toner deinking

    SciTech Connect

    Snyder, B.A.; Berg, J.C. . Chemical Engineering Dept.)

    1994-05-01

    An alternative agglomeration technique for deinking toner-printed furnishes has been investigated. This technique requires only the addition of an immiscible hydrocarbon oil dispersed in water at dosages of approximately 1% by weight on fiber. The addition is made during repulping: the process appears to be effective at all temperatures of interest (23 C and 70 C are tested) and requires no surfactants or additional chemicals. The result of the oil addition is the agglomeration of the toner particles into spheres of 1 mm to 1 cm in size. These spheres contain the added oil which acts as a binder, holding the toner particles together by liquid bridges. The process is ineffective when the furnish contains highly sized fibers or starched paper, and future work seeks to address these crucial problems.

  17. Vectorized image segmentation via trixel agglomeration

    DOEpatents

    Prasad, Lakshman; Skourikhine, Alexei N.

    2006-10-24

    A computer implemented method transforms an image comprised of pixels into a vectorized image specified by a plurality of polygons that can be subsequently used to aid in image processing and understanding. The pixelated image is processed to extract edge pixels that separate different colors and a constrained Delaunay triangulation of the edge pixels forms a plurality of triangles having edges that cover the pixelated image. A color for each one of the plurality of triangles is determined from the color pixels within each triangle. A filter is formed with a set of grouping rules related to features of the pixelated image and applied to the plurality of triangle edges to merge adjacent triangles consistent with the filter into polygons having a plurality of vertices. The pixelated image may be then reformed into an array of the polygons, that can be represented collectively and efficiently by standard vector image.

  18. Bed surface bed profile adjustments to a series of water pulses in gravel bed rivers

    NASA Astrophysics Data System (ADS)

    Ferrer-Boix, C.; Hassan, M. A.

    2014-12-01

    This research aims to explore the interactions between the bed surface texture, the bed topography and the sediment transport (rate and grain size distribution) to a series of water pulses in gravel bed-rivers. We conducted a set of runs in a 18 m-long tilting flume, 1 m-wide. Low flow discharges (Q = 65 l/s) during periods of variable duration (between t = 10 h and t = 1 h) were alternated with high flow rates (Q = 90 l/s) of constant duration (t = 1.5 h). Sediment was fed at a constant rate (Qfeed = 7.5 kg/h) throughout the runs. Eight experiments were consecutively conducted: the final configuration of the previous run was the initial condition for the subsequent experiment. The initial bed texture of the experiments was obtained after a 280 h-long run at low flow, the last 40 h of which under starving conditions. The initial bed slope was S0 = 0.022 m/m. A poorly-sorted grain size distribution (Dg = 5.65 mm and sg = 3.05) was used as a feeding material. The same material was used as the initial condition for the antecedent experiment (280 h-long). Intensive measurements of the bed surface, bed topography and sediment transport were taken during the runs. Provisional results of the experimental campaign demonstrate that: (i) bed topography rapidly adjusts to water pulses: bed aggrades during low flow periods to subsequently degrade during water pulses. However, the rate of change of the bed profile decreases with the number of water pulses; (ii) the surface texture maintains an approximately invariant texture during the runs with no significant changes before and after the pulses; (iii) bedload transport dramatically adjusts to water pulses (increasing its rate and getting coarser). The relative increase in the bedload transport during the pulses diminishes as the number of pulses increases. A detailed analysis of the evolution of the bed profile shows the formation of transverse ribs during low flow periods which slowly migrate upstream. These bedforms are not

  19. Influence of hydrostatic pressure and sound amplitude on the ultrasound induced dispersion and de-agglomeration of nanoparticles.

    PubMed

    Sauter, C; Emin, M A; Schuchmann, H P; Tavman, S

    2008-04-01

    In most applications, nanoparticles are required to be in a well-dispersed state prior to commercialisation. Conventional technology for dispersing particles into liquids, however, usually is not sufficient, since the nanoparticles tend to form very strong agglomerates requiring extremely high specific energy inputs in order to overcome the adhesive forces. Besides conventional systems as stirred media mills, ultrasound is one means to de-agglomerate nanoparticles in aqueous dispersions. In spite of several publications on ultrasound emulsification there is insufficient knowledge on the de-agglomeration of nanoparticulate systems in dispersions and their main parameters of influence. Aqueous suspensions of SiO2-particles were stressed up to specific energies EV of 10(4) kJ/m3 using ultrasound. Ultrasonic de-agglomeration of nanoparticles in aqueous solution is considered to be mainly a result of cavitation. Both hydrostatic pressure of the medium and the acoustic amplitude of the sound wave affect the intensity of cavitation. Furthermore, the presence of gas in the dispersion medium influences cavitation intensity and thus the effectiveness of the de-agglomeration process. In this contribution both, the influence of these parameters on the result of dispersion and the relation to the specific energy input are taken into account. For this, ultrasound experiments were carried out at different hydrostatic pressure levels (up to 10 bars) and amplitude values (64-123 microm). Depending on the optimisation target (time, energy input,...) different parameters limit the dispersion efficiency and result. All experimental results can be explained with the specific energy input that is a function of the primary input parameters of the process. PMID:17977777

  20. Parallel Element Agglomeration Algebraic Multigrid and Upscaling Library

    Energy Science and Technology Software Center (ESTSC)

    2015-02-19

    ParFELAG is a parallel distributed memory C++ library for numerical upscaling of finite element discretizations. It provides optimal complesity algorithms ro build multilevel hierarchies and solvers that can be used for solving a wide class of partial differential equations (elliptic, hyperbolic, saddle point problems) on general unstructured mesh (under the assumption that the topology of the agglomerated entities is correct). Additionally, a novel multilevel solver for saddle point problems with divergence constraint is implemented.

  1. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  2. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  3. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  4. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  5. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  6. Reversible or not? Distinguishing agglomeration and aggregation at the nanoscale.

    PubMed

    Sokolov, Stanislav V; Tschulik, Kristina; Batchelor-McAuley, Christopher; Jurkschat, Kerstin; Compton, Richard G

    2015-10-01

    Nanoparticles are prone to clustering either via aggregation (irreversible) or agglomeration (reversible) processes. It is exceedingly difficult to distinguish the two via conventional techniques such as dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), or electron microscopy imaging (scanning electron microscopy (SEM), transmission electron microscopy (TEM)) as such techniques only generally confirm the presence of large particle clusters. Herein we develop a joint approach to tackle the issue of distinguishing between nanoparticle aggregation vs agglomeration by characterizing a colloidal system of Ag NPs using DLS, NTA, SEM imaging and the electrochemical nanoimpacts technique. In contrast to the conventional techniques which all reveal the presence of large clusters of particles, electrochemical nanoimpacts provide information regarding individual nanoparticles in the solution phase and reveal the presence of small nanoparticles (<30 nm) even in high ionic strength (above 0.5 M KCl) and allow a more complete analysis. The detection of small nanoparticles in high ionic strength media evidence the clustering to be a reversible process. As a result it is concluded that agglomeration rather than irreversible aggregation takes place. This observation is of general importance for all colloids as it provides a feasible analysis technique for a wide range of systems with an ability to distinguish subtly different processes. PMID:26352558

  7. Nifedipine Nanoparticle Agglomeration as a Dry Powder Aerosol Formulation Strategy

    PubMed Central

    Plumley, Carl; Gorman, Eric M.; Munson, Eric J.; Berkland, Cory

    2009-01-01

    Efficient administration of drugs represents a leading challenge in pulmonary medicine. Dry powder aerosols are of great interest compared to traditional aerosolized liquid formulations in that they may offer improved stability, ease of administration, and simple device design. Particles 1–5 µm in size typically facilitate lung deposition. Nanoparticles may be exhaled as a result of their small size; however, they are desired to enhance the dissolution rate of poorly soluble drugs. Nanoparticles of the hypertension drug nifedipine were co-precipitated with stearic acid to form a colloid exhibiting negative surface charge. Nifedipine nanoparticle colloids were destabilized by using sodium chloride to disrupt the electrostatic repulsion between particles as a means to achieve the agglomerated nanoparticles of a controlled size. The aerodynamic performance of agglomerated nanoparticles was determined by cascade impaction. The powders were found to be well suited for pulmonary delivery. In addition, nanoparticle agglomerates revealed enhanced dissolution of the drug species suggesting the value of this formulation approach for poorly water soluble pulmonary medicines. Ultimately, nifedipine powders are envisioned as an approach to treat pulmonary hypertension. PMID:19015016

  8. Combustion of metal agglomerates in a solid rocket core flow

    NASA Astrophysics Data System (ADS)

    Maggi, Filippo; Dossi, Stefano; DeLuca, Luigi T.

    2013-12-01

    The need for access to space may require the use of solid propellants. High thrust and density are appealing features for different applications, spanning from boosting phase to other service applications (separation, de-orbiting, orbit insertion). Aluminum is widely used as a fuel in composite solid rocket motors because metal oxidation increases enthalpy release in combustion chamber and grants higher specific impulse. Combustion process of metal particles is complex and involves aggregation, agglomeration and evolution of reacting particulate inside the core flow of the rocket. It is always stated that residence time should be enough in order to grant complete metal oxidation but agglomerate initial size, rocket grain geometry, burning rate, and other factors have to be reconsidered. New space missions may not require large rocket systems and metal combustion efficiency becomes potentially a key issue to understand whether solid propulsion embodies a viable solution or liquid/hybrid systems are better. A simple model for metal combustion is set up in this paper. Metal particles are represented as single drops trailed by the core flow and reacted according to Beckstead's model. The fluid dynamics is inviscid, incompressible, 1D. The paper presents parametric computations on ideal single-size particles as well as on experimental agglomerate populations as a function of operating rocket conditions and geometries.

  9. Dual Fluidized Bed Biomass Gasification

    SciTech Connect

    2005-09-30

    The dual fluidized bed reactor is a recirculating system in which one half of the unit operates as a steam pyrolysis device for biomass. The pyrolysis occurs by introducing biomass and steam to a hot fluidized bed of inert material such as coarse sand. Syngas is produced during the pyrolysis and exits the top of the reactor with the steam. A crossover arm, fed by gravity, moves sand and char from the pyrolyzer to the second fluidized bed. This sand bed uses blown air to combust the char. The exit stream from this side of the reactor is carbon dioxide, water and ash. There is a second gravity fed crossover arm to return sand to the pyrolysis side. The recirculating action of the sand and the char is the key to the operation of the dual fluidized bed reactor. The objective of the project was to design and construct a dual fluidized bed prototype reactor from literature information and in discussion with established experts in the field. That would be appropriate in scale and operation to measure the relative performance of the gasification of biomass and low ranked coals to produce a high quality synthesis gas with no dilution from nitrogen or combustion products.

  10. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

    A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.