Science.gov

Sample records for solid debris bed

  1. Debris-bed friction of hard-bedded glaciers

    USGS Publications Warehouse

    Cohen, D.; Iverson, N.R.; Hooyer, T.S.; Fischer, U.H.; Jackson, M.; Moore, P.L.

    2005-01-01

    [1] Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500 kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1. A small exponent (n < 2) is likely because stresses in ice are small and flow is transient. Numerical calculations of the bed-normal drag force on a sphere in contact with a flat bed using n = 1 show that this force can reach values several hundred times that on a sphere isolated from the bed, thus drastically increasing frictional resistance. Various estimates of basal friction are obtained from this model. For example, the shear traction at the bed of a glacier sliding at 20 m a-1 with a geothermally induced melt rate of 0.006 m a-1 and an effective pressure of 300 kPa can exceed 100 kPa. Debris-bed friction can therefore be a major component of sliding resistance, contradicting the common assumption that debris-bed friction is negligible. Copyright 2005 by the American Geophysical Union.

  2. D7 debris-bed experiment. [LMFBR

    SciTech Connect

    Mitchell, G W; Ottinger, C A; Lipinski, R J

    1983-08-01

    The D7 experiment investigated heat removal from a shallow, stratified bed of UO/sub 2/ particulate in sodium. The particle diameters ranged from 0.1 to 1.0 mm, with the largest particles at the bottom. The bed thickness was 74 mm and the average porosity was 41%. The incipient dryout power varied from 0.43 W/g to 0.25 W/g as the sodium subcooling (saturation temperature minus overlying pool temperature) was reduced from 390/sup 0/C to 170/sup 0/C. These powers were only slighlty above the incipient boiling powers. Such low dryout powers are believed due to the interaction of capillary force with bed stratification. With a subccoling of 130/sup 0/C several sudden decreases in the saturation temperature occurred. These are believed due to channel formation, which causes a reduction in the capillary pressure in the bed.

  3. Quench cooling of superheated debris beds in containment during LWR core meltdown accidents

    SciTech Connect

    Ginsberg, T.; Chen, J.C.

    1984-01-01

    Light water reactor core meltdown accident sequence studies suggest that superheated debris beds may settle on the concrete floor beneath the reactor vessel. A model for the heat transfer processes during quench of superheated debris beds cooled by an overlying pool of water has been presented in a prior paper. This paper discusses the coolability of decay-heated debris beds from the standpoint of their transient quench characteristics. It is shown that even though a debris bed configuration may be coolable from the point of view of steady-state decay heat removal, the quench behavior from an initially elevated temperature may lead to bed melting prior to quench of the debris.

  4. BWR lower plenum debris bed models for MELCOR

    SciTech Connect

    Hodge, S.A.; Ott, L.J.

    1991-01-01

    Work is underway at Oak Ridge National Laboratory (ORNL) to incorporate certain models of the Boiling Water Reactor Severe Accident Response (BWRSAR) code into a local version of MELCOR. Specifically, the BWR lower plenum debris bed and bottom head response models taken from BWRSAR are being tested within the local MELCOR code structure. Upon successful completion of testing, recommendations for formal adoption of these models will be made to the Nuclear Regulatory Commission (NRC) and to the MELCOR code development staff at Sandia National Laboratories (SNL). The SNL code development staff retain exclusive responsibility for maintaining the configuration control for the official version of MELCOR. The BWR lower plenum debris bed and bottom head response models permit the calculation of heatup, melting, and relocation of the debris after dryout. They predict the response of the lower plenum internal structures and the bottom head as well as the composition and timing of material release from the vessel. They have been previously applied in severe accident analyses for the Containment Performance Improvement (CPI) Program and the Mark I shell survivability study (NUREG/CR-5423), and in recent assessments of candidate accident management strategies. This paper provides a brief description of the purpose and operation of these models. 11 refs., 15 figs., 5 tabs.

  5. Space Shuttle Solid Rocket Booster Debris Assessment

    NASA Technical Reports Server (NTRS)

    Kendall, Kristin; Kanner, Howard; Yu, Weiping

    2006-01-01

    The Space Shuttle Columbia Accident revealed a fundamental problem of the Space Shuttle Program regarding debris. Prior to the tragedy, the Space Shuttle requirement stated that no debris should be liberated that would jeopardize the flight crew and/or mission success. When the accident investigation determined that a large piece of foam debris was the primary cause of the loss of the shuttle and crew, it became apparent that the risk and scope of - damage that could be caused by certain types of debris, especially - ice and foam, were not fully understood. There was no clear understanding of the materials that could become debris, the path the debris might take during flight, the structures the debris might impact or the damage the impact might cause. In addition to supporting the primary NASA and USA goal of returning the Space Shuttle to flight by understanding the SRB debris environment and capability to withstand that environment, the SRB debris assessment project was divided into four primary tasks that were required to be completed to support the RTF goal. These tasks were (1) debris environment definition, (2) impact testing, (3) model correlation and (4) hardware evaluation. Additionally, the project aligned with USA's corporate goals of safety, customer satisfaction, professional development and fiscal accountability.

  6. Entrainment of bed sediment by debris flows: results from large-scale experiments

    USGS Publications Warehouse

    Reid, Mark E.; Iverson, Richard M.; Logan, Matthew; LaHusen, Richard G.; Godt, Jonathan W.; Griswold, Julie P.

    2011-01-01

    When debris flows grow by entraining sediment, they can become especially hazardous owing to increased volume, speed, and runout. To investigate the entrainment process, we conducted eight largescale experiments in the USGS debris-flow flume. In each experiment, we released a 6 m3 water-saturated debris flow across a 47-m long, ~12-cm thick bed of partially saturated sediment lining the 31º flume. Prior to release, we used low-intensity overhead sprinkling and real-time monitoring to control the bed-sediment wetness. As each debris flow descended the flume, we measured the evolution of flow thickness, basal total normal stress, basal pore-fluid pressure, and sediment scour depth. When debris flows traveled over relatively dry sediment, net scour was minimal, but when debris flows traveled over wetter sediment (volumetric water content > 0.22), debris-flow volume grew rapidly and flow speed and runout were enhanced. Data from scour sensors showed that entrainment occurred by rapid (5-10 cm/s), progressive scour rather than by mass failure at depth. Overriding debris flows rapidly generated high basal pore-fluid pressures when they loaded and deformed bed sediment, and in wetter beds these pressures approached lithostatic levels. Reduction of intergranular friction within the bed sediment thereby enhanced scour efficiency, entrainment, and runout.

  7. Drying of solids in fluidized beds

    SciTech Connect

    Kannan, C.S.; Thomas, P.P.; Varma, Y.B.G.

    1995-09-01

    Fluidized bed drying is advantageously adopted in industrial practice for drying of granular solids such as grains, fertilizers, chemicals, and minerals either for long shelf life or to facilitate further processing or handling. Solids are dried in batch and in continuous fluidized beds corresponding to cross-flow and countercurrent flow of phases covering a wide range in drying conditions. Materials that essentially dry with constant drying rate and then give a falling drying rate approximately linear with respect to solids moisture content (sand) as well as those with an extensive falling rate period with the subsequent falling rate being a curve with respect to the moisture content (mustard, ragi, poppy seeds) are chosen for the study. The performance of the continuous fluidized bed driers is compared with that of batch fluidized bed driers; the performance is predicted using batch kinetics, the residence time distribution of solids, and the contact efficiency between the phases.

  8. Solids feed nozzle for fluidized bed

    DOEpatents

    Zielinski, Edward A.

    1982-01-01

    The vertical fuel pipe of a fluidized bed extends up through the perforated support structure of the bed to discharge granulated solid fuel into the expanded bed. A cap, as a deflecting structure, is supported above the discharge of the fuel pipe and is shaped and arranged to divert the carrier fluid and granulated fuel into the combusting bed. The diverter structure is spaced above the end of the fuel pipe and provided with a configuration on its underside to form a venturi section which generates a low pressure in the stream into which the granules of solid fuel are drawn to lengthen their residence time in the combustion zone of the bed adjacent the fuel pipe.

  9. Application of debris-bed dryout data to CONACS-1 modeling

    SciTech Connect

    Gabor, J.D.; Cassulo, J.C.; Pedersen, D.R.

    1982-01-01

    CONACS-1 (the first version of the DOE Containment Analysis Code System) which is currently under development requires extension of existing debris-bed dryout data to the wide range of conditions possible in an accident sequence. While there has been much effort on modeling of debris-bed dryout from first principles, there is no definitive model for beds of irregularly shaped particles of wide size distribution and for beds of varying heights. Existing debris-bed heat-transfer data with real materials are for the most part limited to dryout as a function of bed depth for adiabatic conditions of atmospheric pressure. These data must be extrapolated with the use of appropriate theoretical models based on experimentation with simulant materials to the ocnditions under consideration in the containment analysis. The data base selected for CONACS-1 is from measurements of dryout for beds of 100 to 1000 ..mu..m UO/sub 2/ with the sodium phase Joule heated. This particle size range which is typical for debris from fuel-coolant interactions is the most reasonable to use.

  10. Field observations of pressure fluctuations in debris flows and debris floods at the Illgraben torrent channel with implications for channel-bed erosion

    NASA Astrophysics Data System (ADS)

    McArdell, Brian

    2014-05-01

    The Illgraben catchment in southwestern Switzerland experiences frequent debris flows and debris floods, providing an ideal location to study the properties of debris flows. A large (2m long, 4m wide) force plate in the channel bed is outfitted with normal and shear force sensors as well as a geophone and an accelerometer. A vertical flow-parallel concrete wall immediately upstream of the large force plate is instrumented with 18 geophones and 6 force plates, each mounted on a 0.3m by 0.3m square steel plate. The flow height near the wall and over the force plate are measured using laser sensors. Three video cameras have been installed to record the passage of debris flows. While the measurement system was designed for observing debris flows, large debris floods also trigger the observation station, providing an opportunity to compare their flow properties. Debris flows tend to have steep flow fronts, with flow depths increasing from 0 to several meters over about 10 seconds; the flow front generally appears to be granular with little turbulent water visible on the surface. Debris floods tend to have undular fronts which visibly resemble flash floods, increasing from flow depths on the order of a few cm to several meters typically over several 100's of seconds. Both types of flow produce strong fluctuations in normal force on the channel bed, however the magnitude of fluctuations at the base of debris flows tend to be substantially larger than in debris floods. In debris flows the pressure fluctuations are largest at the bed and decrease in amplitude with height above the channel bed, which is consistent with the idea that the pressure fluctuations in the flow are generated at the contact between the debris flow and channel bed. Pressure fluctuations in debris floods (when the measuring system at the wall is triggered) are much smaller. Mean shear stresses on the channel bed are similar in both types of flow, however the pressure fluctuations at the base of debris

  11. Positive feedback and momentum growth during debris-flow entrainment of wet bed sediment

    USGS Publications Warehouse

    Iverson, R.M.; Reid, M.E.; Logan, M.; LaHusen, R.G.; Godt, J.W.; Griswold, J.P.

    2011-01-01

    Debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep, debris-mantled slopes. The flows can then grow dramatically in size and speed as they entrain material from their beds and banks, but the mechanism of this growth is unclear. Indeed, momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged. Here we use data from large-scale experiments to assess the entrainment of bed material by debris flows. We find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows. The increased pore pressure facilitates progressive scour of the bed, reduces basal friction and instigates positive feedback that causes flow speed, mass and momentum to increase. If dryer bed sediment is entrained, however, the feedback becomes negative and flow momentum declines. We infer that analogous feedbacks could operate in other types of gravity-driven mass flow that interact with erodible beds. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  12. Summary of Disposable Debris Shields (DDS) Analysis for Development of Solid Debris Collection at NIF

    SciTech Connect

    Shaughnessy, D A; Moody, K J; Grant, P M; Lewis, L A; Hutcheon, I D; Lindvall, R; Gostic, J M

    2011-11-20

    Collection of solid debris from the National Ignition Facility (NIF) is being developed both as a diagnostic tool and as a means for measuring nuclear reaction cross sections relevant to the Stockpile Stewardship Program and nuclear astrophysics. The concept is straightforward; following a NIF shot, the debris that is produced as a result of the capsule and hohlraum explosion would be collected and subsequently extracted from the chamber. The number of nuclear activations that occurred in the capsule would then be measured through a combination of radiation detection and radiochemical processing followed by mass spectrometry. Development of the catcher is challenging due to the complex environment of the NIF target chamber. The collector surface is first exposed to a large photon flux, followed by the debris wind that is produced. The material used in the catcher must be mechanically strong in order to withstand the large amount of energy it is exposed to, as well as be chemically compatible with the form and composition of the debris. In addition, the location of the catcher is equally important. If it is positioned too close to the center of the target chamber, it will be significantly ablated, which could interfere with the ability of the debris to reach the surface and stick. If it is too far away, the fraction of the debris cloud collected will be too small to result in a statistically significant measurement. Material, geometric configuration, and location must all be tested in order to design the optimal debris collection system for NIF. One of the first ideas regarding solid debris collection at NIF was to use the disposable debris shields (DDS), which are fielded over the final optics assemblies (FOA) 7 m away from the center of the target chamber. The DDS are meant to be replaced after a certain number of shots, and if the shields could be subsequently analyzed after removal, it would serve as a mechanism for fielding a relatively large collection area

  13. D5 debris bed experiment-extended post-dryout observations of a UO/sub 2/-sodium particle bed. [In ACPR reactor

    SciTech Connect

    Gronager, J E

    1982-01-01

    The D5 experiment is the sixth in a series of debris bed coolability experiments. The principal objective of the experiment is to investigate debris bed behavior, for various sodium subcoolings, at temperatures exceeding 2100/sup 0/K. The experiment is scheduled for early February 1982.

  14. Design report on SCDAP/RELAP5 model improvements - debris bed and molten pool behavior

    SciTech Connect

    Allison, C.M.; Rempe, J.L.; Chavez, S.A.

    1994-11-01

    the SCDAP/RELAP5/MOD3 computer code is designed to describe the overall reactor coolant system thermal-hydraulic response, core damage progression, and in combination with VICTORIA, fission product release and transport during severe accidents. Improvements for existing debris bed and molten pool models in the SCDAP/RELAP5/MOD3.1 code are described in this report. Model improvements to address (a) debris bed formation, heating, and melting; (b) molten pool formation and growth; and (c) molten pool crust failure are discussed. Relevant data, existing models, proposed modeling changes, and the anticipated impact of the changes are discussed. Recommendations for the assessment of improved models are provided.

  15. First Stage Solid Propellant Multiply Debris Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Toleman, Benjamin M.

    2011-01-01

    Destruction of a solid rocket stage of a launch vehicle can create a thermal radiation hazard for an aborting crew module. This hazard was assessed for the Constellation Program (Cx) crew and launch vehicle concept. For this concept, if an abort was initiated in first stage flight, the Crew Module (CM) will separate and be pulled away from the malfunctioning launch vehicle via a Launch Abort System (LAS). Having aborted the mission, the launch vehicle will likely be destroyed via a Flight Termination System (FTS) in order to prevent it from errantly traversing back over land and posing a risk to the public. The resulting launch vehicle debris field, composed primarily of first stage solid propellant, poses a threat to the CM. The harsh radiative thermal environment, caused by surrounding burning propellant debris, may lead to CM parachute failure. A methodology, detailed herein, has been developed to address this concern and to quantify the risk of first stage propellant debris leading to the thermal demise of the CM parachutes. Utilizing basic thermal radiation principles, a software program was developed to calculate parachute temperature as a function of time for a given abort trajectory and debris piece trajectory set. Two test cases, considered worst case aborts with regard to launch vehicle debris environments, were analyzed using the simulation: an abort declared at Mach 1 and an abort declared at maximum dynamic pressure (Max Q). For both cases, the resulting temperature profiles indicated that thermal limits for the parachutes were not exceeded. However, short duration close encounters by single debris pieces did have a significant effect on parachute temperature. Therefore while these two test cases did not indicate exceedance of thermal limits, in order to quantify the risk of parachute failure due to radiative effects from the abort environment, a more thorough probability-based analysis using the methodology demonstrated herein must be performed.

  16. First Stage Solid Propellant Multi Debris Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Toleman, Benjamin M.

    2011-01-01

    The crew launch vehicle considered for the Constellation (Cx) Program utilizes a first stage solid rocket motor. If an abort is initiated in first stage flight the Crew Module (CM) will separate and be pulled away from the launch vehicle via a Launch Abort System (LAS) in order to safely and quickly carry the crew away from the malfunction launch vehicle. Having aborted the mission, the launch vehicle will likely be destroyed via a Flight Termination System (FTS) in order to prevent it from errantly traversing back over land and posing a risk to the public. The resulting launch vehicle debris field, composed primarily of first stage solid propellant, poses a threat to the CM. The harsh radiative thermal environment induced by surrounding burning propellant debris may lead to CM parachute failure. A methodology, detailed herein, has been developed to address this concern and quantify the risk of first stage propellant debris leading to radiative thermal demise of the CM parachutes. Utilizing basic thermal radiation principles, a software program was developed to calculate parachute temperature as a function of time for a given abort trajectory and debris piece trajectory set. Two test cases, considered worst-case aborts with regard to launch vehicle debris environments, were analyzed using the simulation: an abort declared at Mach 1 and an abort declared at maximum dynamic pressure (Max Q). For both cases, the resulting temperature profiles indicated that thermal limits for the parachutes were not exceeded. However, short duration close encounters by single debris pieces did have a significant effect on parachute temperature, with magnitudes on the order of 10 s of degrees Fahrenheit. Therefore while these two test cases did not indicate exceedance of thermal limits, in order to quantify the risk of parachute failure due to radiative effects from the abort environment, a more thorough probability-based analysis using the methodology demonstrated herein must be

  17. RESPONSE OF FISHES AND AQUATIC HABITATS TO SAND-BED STREAM RESTORATION USING LARGE WOODY DEBRIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large woody debris structures hold promise as cost-effective stream corridor rehabilitation measures. Pre- and post construction data are presented that describe effects of habitat rehabilitation of Little Topashaw Creek, a sinuous, fourth-order sand-bed stream draining 37 km2 in northwest Mississip...

  18. Fluid bed solids heater. Final technical report

    SciTech Connect

    Preuit, L. C.

    1980-01-01

    A solids heater which operates at up to 2000 F was designed, fabricated, installed and operated through checkout at the Morgantown Energy Technology Center at Morgantown, West Virginia. The system, designated the 2000 F Fluid Bed Solids Heater (FBSH) uses a fluidized bed to heat limestone to 600 F and aluminium oxide or silicon carbide to 2000 F and discharges heated solids upon demand. The FBSH with added valve handling and pressurization equipment is known as the Valve Hot Solids Test Unit and is intended for use by the US Department of Energy for testing of valves for severe service applications in coal conversion and utilization processes. The FBSH as designed and supplied by Combustion Power Company includes process equipment, controls, the enclosing building and other associated equipment. In the 600 F range of operation it can circulate limestone through two valve test trains simultaneously on a continuous basis. Only one valve test train is used for 2000 F solids and operation in that range is also continuous. Limestone, crushed to minus 5/16 size, is heated, discharged, and recycled at a maximum average rate of 250 lb/min while aluminum oxide or silicon carbide, No. 8 grit, is circulated at rates up to 167 lb/min. The FBSH control system is designed for automatic operation, and capability is included for external computerized data acquisition and/or supervisory control. An operating and maintenance manual and as-built drawings have been submitted. This report describes the FBSH equipment, its design basis, and its operation. It has been prepared and submitted in fulfillment of Contract Number DIAC05-77ET10499.

  19. Certification of the NAC-LWT cask for shipment of sodium debris bed experiments.

    SciTech Connect

    Liu, Y.; Shah, V.; Fabian, R.; Shuler, J.

    2008-01-01

    The Department of Energy Headquarters Certifying Official has issued a Certificate of Compliance for the shipment of sodium debris bed experiments (DBE) in the NAC International's Legal Weight Truck (NAC-LWT) casks. The shipment is part of a major de-inventory project at Sandia National Laboratories. The sodium debris bed experiments consist of crucibles containing UO{sub 2} immersed in sodium. The uranium is 93% enriched U{sup 235}. Potential sodium-water reaction and criticality safety under hypothetical accident conditions of transport are the two major technical issues for the design and certification of the NAC-LWT casks for the DBE shipment. The certification review took {approx} 13 months, including one round of questions and responses and source-verification QA audits of the fabrication and welding of the DBE transport canisters at two locations.

  20. Idealized debris flow in flume with bed driven by a conveyor belt

    USGS Publications Warehouse

    Ling, Chi-Hai; Chen, Cheng-lung

    1989-01-01

    The generalized viscoplastic fluid (GVF) model is used to derive the theoretical expressions of two-dimensional velocities and surface profile for debris flow established in a flume with bed driven by a conveyor belt. The rheological parameters of the GVF model are evaluated through the comparison of theoretical results with measured data. A slip velocity of the established (steady) nonuniform flow on the moving bed (i.e., the conveyor belt) is observed, and a relation between the slip velocity and the velocity gradient at the bed is derived. Two belts, one rough and the other smooth, were tested. The flow profile in the flume is found to be linear and dependent on the roughness of the belt, but not much on its speed.

  1. Interaction of debris with a solid obstacle: numerical analysis.

    PubMed

    Kosinska, Anna

    2010-05-15

    The subject of this research is the propagation of a cloud of solid particles formed from an explosion-damaged construction. The main objective is the interaction of the cloud (debris) with a solid beam located at some distance from the explosion. The mathematical model involves the flow of the gas using standard conservation equations, and this part of the model is solved numerically. The solid particles are treated as a system of solid points (so-called Lagrangian approach), whose motion is the result of the flowing gas as well as collisions with obstacles. These two issues are described respectively by Newton's second law and the hard-sphere model. The model is used to simulate various cases where the influence of different parameters like the value of the pressure of the explosion, the particle size, the number of particles and the obstacle location are investigated. The results are presented as snapshots of particle location, and also as the particle total momentum during collision with the beam. PMID:20060218

  2. INVESTIGATION OF FLUID BED COMBUSTION OF MUNICIPAL SOLID WASTE

    EPA Science Inventory

    An experimental study was undertaken to burn processed municipal solid waste in a fluid-bed combustor containing water-cooled tubes in the bed. The 300-hour test was performed without incident and terminated on schedule. The combustor and ducting were clean on inspection after th...

  3. Hydraulic modeling of unsteady debris-flow surges with solid-fluid interactions

    USGS Publications Warehouse

    Iverson, Richard M.

    1997-01-01

    Interactions of solid and fluid constituents produce the unique style of motion that typifies debris flows. To simulate this motion, a new hydraulic model represents debris flows as deforming masses of granular solids variably liquefied by viscous pore fluid. The momentum equation of the model describes how internal and boundary forces change as coarse-grained surge heads dominated by grain-contact friction grade into muddy debris-flow bodies more strongly influenced by fluid viscosity and pressure. Scaling analysis reveals that pore-pressure variations can cause flow resistance in surge heads to surpass that in debris-flow bodies by orders of magnitude. Numerical solutions of the coupled momentum and continuity equations provide good predictions of unsteady, nonuniform motion of experimental debris flows from initiation through deposition.

  4. SOLIDS TRANSPORT BETWEEN ADJACENT CAFB FLUIDIZED BEDS

    EPA Science Inventory

    The report gives results of an experimental investigation of a pulsed, dense-phase pneumatic transport system for controlled circulation between adjacent fluidized beds. A model was developed to predict performance. The program provides technical support for EPA's program to demo...

  5. Model of Fluidized Bed Containing Reacting Solids and Gases

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Lathouwers, Danny

    2003-01-01

    A mathematical model has been developed for describing the thermofluid dynamics of a dense, chemically reacting mixture of solid particles and gases. As used here, "dense" signifies having a large volume fraction of particles, as for example in a bubbling fluidized bed. The model is intended especially for application to fluidized beds that contain mixtures of carrier gases, biomass undergoing pyrolysis, and sand. So far, the design of fluidized beds and other gas/solid industrial processing equipment has been based on empirical correlations derived from laboratory- and pilot-scale units. The present mathematical model is a product of continuing efforts to develop a computational capability for optimizing the designs of fluidized beds and related equipment on the basis of first principles. Such a capability could eliminate the need for expensive, time-consuming predesign testing.

  6. Fluidization onset and expansion of gas-solid fluidized beds

    SciTech Connect

    Jones, O.C.; Shin, T.S.

    1984-08-01

    A simple, mass conservation-based, kinematic model is presented for accurately predicting both the onset of fluidization and the degree of (limit of) bed expansion in bubbling gas-solid fluidized beds. The model is consistant with inception correlations exisiting in the literature. Since the method has a sound physical basis, it might be expected to provide scaling between laboratory-scale fluidized beds and large-scale systems. This scaling ability, however, remains to be demonstrated as does the application to pressurized systems and where the terminal Reynolds numbers exceed 1000, (Archimedes numbers over about 3.2 x 10/sup 5/).

  7. Direct measurements of bed sediment entrainment and basal stress from the headwaters of a natural debris-flow basin

    NASA Astrophysics Data System (ADS)

    McCoy, S. W.; Kean, J. W.; Coe, J. A.; Tucker, G. E.; Staley, D. M.; Wasklewicz, T. A.

    2010-12-01

    When mixtures of soil, rock and water flow down slope as a debris flow they can entrain and transport large amounts of bed sediment and erode underlying bedrock. Although sediment entrainment and bedrock scour by debris flows are commonplace in steep terrain, there are few measurements to constrain key terms in event-scale debris-flow routing models or longer-term landscape evolution models that include the effects of bedrock erosion by debris-flows. Particularly conspicuous are the lack of bed sediment entrainment measurements and measurements of the evolving stress state at the flow-bedrock interface as the shielding layer of sediment is removed and sediment entrainment gives way to bedrock erosion. Here we present data from the headwaters of a debris-flow basin at Chalk Cliffs, Colorado, where we directly measured entrainment of channel sediment and the evolving stress state at the bedrock interface during three debris-flow events. We made these measurements through the combined the use of a novel sediment entrainment sensor and a force plate with more commonly used video imagery and instrumentation, to measure pore-fluid pressure, flow stage, soil moisture, and rainfall during the three debris-flow events. We extended these at-a-point process measurements to evaluate the reach-scale response using pre- and post-event terrestrial laser scans. During the three separate debris-flow events approximately 1.1 m, 0.5 m, and 0.4 m of unconsolidated bed sediment were entrained. Following entrainment of the sediment, bedrock was scoured by flows that ranged from water-poor coarse-grained surge fronts to water-rich turbulent flows with vigorous bedload transport. In all cases, entrainment of bed sediment was progressive, rather than by a single en masse failure of the sediment at the sediment-bedrock interface. The measured rates were dependent on bed sediment water content. When the bed sediment was unsaturated, entrainment was relatively slow, generally taking several

  8. Kinetic behavior of solid particles in fluidized beds: Annual report

    SciTech Connect

    Kono, H.O.; Huang, C.C.

    1987-10-01

    This report summarizes technical accomplishments for the first year in a 3-year contract project for the Morgantown Energy Technology Center (METC) of the US Department of Energy (DOE) under contract number AC21-86MC23249. The objectives of the project are (1) to develop experimental techniques for measuring the forces of fluidized particles, and (2) to predict solid particle performance in fluidized beds using data analysis and mathematical modeling. During the first year, the fracture-sensitive tracer-particle method was developed and applied to investigate the effects of fluidized particle size, superficial gas velocity, bed height, bed diameter, and bed configuration on the kinetic behavior of solid particles in fluidized beds. Quantitative data and comprehensive information were obtained. A piezoresistive strain-gauge sensor and a PC data-acquisition system were also developed; these are being used to measure the force distribution in fluidized beds. The pressure fluctuation method will also be investigated in the near future. 12 refs., 24 figs., 2 tabs.

  9. Non-local rheology of stony debris flow propagating over a cohesionless sediment bed

    NASA Astrophysics Data System (ADS)

    Lanzoni, Stefano; Gregoretti, Carlo

    2016-04-01

    normal to the flow, with particular attention to the role played by frictional stresses near to the movable bed over which the debris flow propagates.

  10. Fluidized bed gasification of industrial solid recovered fuels.

    PubMed

    Arena, Umberto; Di Gregorio, Fabrizio

    2016-04-01

    The study evaluates the technical feasibility of the fluidized bed gasification of three solid recovered fuels (SRFs), obtained as co-products of a recycling process. The SRFs were pelletized and fed to a pilot scale bubbling fluidized bed reactor, operated in gasification and co-gasification mode. The tests were carried out under conditions of thermal and chemical steady state, with a bed of olivine particles and at different values of equivalence ratio. The results provide a complete syngas characterization, in terms of its heating value and composition (including tars, particulates, and acid/basic pollutants) and of the chemical and physical characterization of bed material and entrained fines collected at the cyclone outlet. The feasibility of the fluidized bed gasification process of the different SRFs was evaluated with the support of a material and substance flow analysis, and a feedstock energy analysis. The results confirm the flexibility of fluidized bed reactor, which makes it one of the preferable technologies for the gasification of different kind of wastes, even in co-gasification mode. The fluidized bed gasification process of the tested SRFs appears technically feasible, yielding a syngas of valuable quality for energy applications in an appropriate plant configuration. PMID:26896004

  11. Combustion of oil palm solid wastes in fluidized bed combustor

    SciTech Connect

    Shamsuddin, A.H.; Sopian, K.

    1995-12-31

    The palm oil industry of Malaysia is the largest in the world producing about 55% of the world production. The industry has approximately 270 mills throughout the country with processing sizes ranging from 10 tonnes/hour to 120 tonnes/hour. All mills produce solid wastes, about 50% of the fresh fruit bunches in terms of weight. The solid wastes produced are in the form of empty fruit bunches, fibers and shells. These wastes have high energy value, ranging from 14 to 18 MJ/kg. The industry is currently self-sufficient in terms of energy. Fibers and shell wastes are being used as boiler fuel to raise steam for electrical power production and process steam. However, the combustion technology currently being employed is obsolete with low efficiency and polluting. A fluidized bed combustor pilot plant is designed and constructed at Combustion Research Laboratory, Universiti Kebangsaan Malaysia. The combustor is made up of 600 mm {times} 900 mm rectangular bed filled with sand up to 400 mm height, static. A bank of heat transfer tubes is imbedded in the bed, designed to absorb 50% of heat released by the fuel in the bed. The remaining heat is transferred in tubes placed on the wall of the freeboard area. Experimental studies were carried out in the pilot plant using palm oil solid wastes. The combustion temperatures were maintained in the range 800--900 C. The performance of the combustor was evaluated in terms of combustion and boiler efficiencies and flue gas emissions monitored.

  12. Collection of Solid Debris on NIF for Radiochemical Diagnostics and Measurements

    SciTech Connect

    Shaughnessy, D A

    2009-02-23

    A system for collecting solid, post-explosion debris samples from the NIF chamber and their subsequent radiochemical analysis is currently under development. If the debris that condenses out of the plasma can be collected and analyzed, the number and type of nuclear reactions that occurred in the capsule material can be determined. this has applications both for radiochemical diagnostics of NIF capsule performance as well as radiochemical measurements relevant to basic science and stockpile stewardship. Several design prototypes have been studied and a prioritized list of radiochemical measurements that could be performed on NIF is under development based on interactions with capsule design, fabrication, and WCI design divisions.

  13. Solids mixing in a three phase fluidized bed containing spherically shaped-porous solid particles

    NASA Astrophysics Data System (ADS)

    Snell, G. J.; Zopff, D.

    1984-05-01

    Solids mixing a 3 phase fluidized bed containing 1.8 mm nominal diameter porous spherically shaped solids was studied using a batch type tracer technique. High speed photography was used to determine concentration time traces of color code solid tracer in a region near the wall of a 2 in. i.d. fluidization tube, located at a vertical elevation about 7 in. above the distributor. An add mixture of water and gaseous nitrogen at room temperature and essentially ambient pressure was used to fluidize a spherically shaped, nickel molybdate on alumina solid phase throughout this study. An empirical steady state mixing time was defined in order to characterize top to bottom of bed solids mixing. This mixing index was in turn correlated with superficial liquid velocity, superficial gas velocity, and an axial characteristic dimension.

  14. The historical contribution of solid rocket motors to the one centimeter debris population

    NASA Technical Reports Server (NTRS)

    Jackson, Albert; Eichler, Peter; Reynolds, Robert; Potter, Andrew; Johnson, Nicholas

    1997-01-01

    The measured small particle population in earth orbit contains cm-sized objects that are not accounted for by breakup fragments. It was proposed that slag ejection during solid rocket motor burn is a contributor to this population. The direct evidence for such slag ejection follows from: observations of the exhausts of vehicles in flight, and engineering data from static firings. A source model is presented to account for the contribution of slag expulsion from solid rocket motors to the debris population. The mass and velocity distribution of the slag effluents are taken into account and used as a source term in the debris environment model. The model is based on the available observation data and on models for slag development and ejection.

  15. Experimental study of debris-bed coolability under pool-boiling conditions. [PWR; BWR; LMFBR

    SciTech Connect

    Catton, I.; Dhir, V.K.; Somerton, C.W.

    1983-05-01

    An experimental investigation has been conducted into the dryout of a bed of inductively heated particles cooled by an overlying liquid pool. Particles of diameters 4763 ..mu..m, 3175 ..mu..m, 1588 ..mu..m, and 589-787 ..mu..m have been used. Acetone and water have been used as the coolant with bed heights varying from 5 to 40 cm. Results are presented in terms of the dryout heat as a function of bed height. It has been found that the ratio of the overlying liquid pool height to the particulate bed height can influence the dryout heat flux. Comparison with other experimetal studies was good and a comparison with proposed theoretical models was also made.

  16. Laser-plasma debris from a rotating cryogenic-solid-Xe target

    SciTech Connect

    Amano, Sho; Inaoka, Yutaka; Hiraishi, Hiroki; Miyamoto, Shuji; Mochizuki, Takayasu

    2010-02-15

    We investigate the characteristics of laser plasma debris that is responsible for damaging optics. The debris is composed of fast ions, neutral particles, and fragments, and originates from a solid Xe target on a rotating drum that we developed as an extreme ultraviolet (EUV) source. The ice fragments appear to be a problem most notably with solid Xe targets; however, we find that the damage induced by Xe ice fragments can be avoided by simply reducing the laser pulse energy. We find the number of fast neutral particles to be an order of magnitude less than the number of ions, and we clarify that the plasma debris is primarily composed of fast ions. In addition, we find that the number of fast ions having a few dozen keV of energy decreases when using the rotating target compared with the rest target. We attribute this to a gas curtain effect from the Xe gas localized at the rotating target surface. We estimate the sputtering rate of the Mo/Si mirror, which is caused primarily by the fast ions, to be 104 nm/1x10{sup 6} shots at 190 mm from the source plasma and at an 11.25 deg. angle from the incident laser beam. Up to the 1x10{sup 6} shots exposure, remarkable degradation of the mirror reflectivity is not observed though the sputtering damages the mirror. Mitigation of the ions by using gas and/or magnetic fields will further improve the mirror lifetime. By comparing with a liquid jet Xe target, we conclude that the sputtering rate per conversion efficiency when using the solid Xe targets on the rotating drum is the same as that when using the liquid Xe targets. The high conversion efficiency of 0.9% in the rotating drum solid Xe target makes this technique useful for developing laser plasma EUV sources.

  17. One-dimensional time-dependent debris bed model. [PWR; BWR

    SciTech Connect

    Gorham-Bergeron, E.

    1982-01-01

    The dryout process is described for a particle bed using a time-dependent one-dimensional porous bed model. The model is based on momentum, energy and mass conservation equations for separated flow. The model is applicable to the case in which capillary forces can be neglected. For the case in which only laminar flow is considered exact algebraic solutions to the equations can be obtained. These are presented. Distinct regimes for the parameterized solutions can be identified and associated with moving fronts in the bed. Extension to the full turbulent and laminar equations is made with the aid of insights gained from solution of the laminar case. Comparison with recent experimental results and theoretical predictions is made. The model is seen to encompass and extend the theoretical models. It suggests additional experiments.

  18. Solid fuel feed system for a fluidized bed

    DOEpatents

    Jones, Brian C.

    1982-01-01

    A fluidized bed for the combustion of coal, with limestone, is replenished with crushed coal from a system discharging the coal laterally from a station below the surface level of the bed. A compartment, or feed box, is mounted at one side of the bed and its interior separated from the bed by a weir plate beneath which the coal flows laterally into the bed while bed material is received into the compartment above the plate to maintain a predetermined minimum level of material in the compartment.

  19. Bulk-density distributions of solids in the freeboard of a gas-solid fluidized bed

    SciTech Connect

    Shen, B.C.; Fan, L.T.; Walawender, W.P.

    1995-05-01

    The freeboard region above the bubbling zone of a gas-solid fluidized bed provides the space not only for the disengagement of particles but also for additional contact and reaction between the particles and gas. The flow pattern and behavior of particles as well as their bulk-density distribution in the freeboard have a significant impact on the efficiency of fluidization. The results of numerous previous experimental studies indicate that the bulk density of solids essentially decreases exponentially as a function of the height of the freeboard. In the present work, this distribution has been obtained by first derived the Fokker-Planck equation from the linearized equation of motion of a single particle and then transforming this Fokker-Planck equation into that for the bulk-density distribution of solids. Its simplification to the one-dimensional case readily gives rise to an exponential distribution and agrees well with the available experimental data.

  20. CHARACTERIZATION OF SOLID RESIDUES FROM FLUIDIZED-BED COMBUSTION UNITS

    EPA Science Inventory

    The report gives results of physical and chemical characterizations of samples of spent bed material and of flyash from three experimental atmospheric and pressurized fluidized-bed combustion (FBC) units. It also gives results of characterization of samples of bed material which ...

  1. Aerosol-Assisted Solid Debris Collection for the National Ignition Facility

    SciTech Connect

    Nelson, S L; Shaughnessy, D A; Moody, K J; Ivanov, V V; Astanovitskiy, A L; Lewis, L A; Rundberg, R S

    2010-05-21

    The National Ignition Facility (NIF) has been completed and has made its first shots on-target. While upcoming experiments will be focused on achieving ignition, a variety of subsequent experiments are planned for the facility, including measurement of cross sections, astrophysical measurements, and investigation of hydrodynamic instability in the target capsule. In order to successfully execute several of these planned experiments, the ability to collect solid debris following a NIF capsule shot will be required. The ability to collect and analyze solid debris generated in a shot at the National Ignition Facility (NIF) will greatly expand the number of nuclear reactions studied for diagnostic purposes. Currently, reactions are limited to only those producing noble gases for cryogenic collection and counting with the Radchem Apparatus for Gas Sampling (RAGS). The radchem solid collection diagnostic has already been identified by NIF to be valuable for the determination and understanding of mix generated in the target capsule's ablation. LLNL is currently developing this solid debris collection capability at NIF, and is in the stage of testing credible designs. Some of these designs explore the use of x-ray generated aerosols to assist in collection of solid debris. However, the variety of harsh experimental conditions this solid collection device will encounter in NIF are challenging to replicate. Experiments performed by Gary Grim et al. at Sandia National Laboratory's RHEPP1 facility have shown that ablation causes a cloud of material removed from an exposed surface to move normal to and away from the surface. This ablation is certain to be a concern in the NIF target chamber from the prompt x-rays, gamma rays, etc. generated in the shot. The cloud of ablated material could interfere with the collection of the desired reaction debris by slowing down the debris so that the kinetic energy is too low to allow implantation, or by stopping the debris from reaching the

  2. Production of amylases from rice by solid-state fermentation in a gas-solid spouted-Bed bioreactor

    PubMed

    Silva; Yang

    1998-07-01

    A gas-solid spouted-bed bioreactor was developed to produce amylases from rice in solid-state fermentation by Aspergillus oryzae. The spouted-bed bioreactor was developed to overcome many of the problems inherent to large-scale solid-state fermentation, including mass- and heat-transfer limitations in the conventional tray reactors and solids-handling difficulties seen in packed-bed bioreactors. The solid-state fermentation results from the tray-type reactor with surface aeration were poor because of mass- and heat-transfer problems. A packed-bed bioreactor with continuous aeration through the rice bed produced high protein and enzymes, but the fermented rice was difficult to remove and process due to the formation of large chunks of rice aggregates knitted together with fungal mycelia. Also, the fermentation was not uniform in the packed bed. The spouted-bed bioreactor with intermittent spouting with air achieved high production levels in both total protein and enzymes (alpha-amylase, beta-amylase, and glucoamylase) that were comparable to those found in the packed-bed bioreactor, but without the nonuniformity and solids-handling problems. However, continual spouting was found to be detrimental to this solid-state fermentation, possibly because of shear or impact damage to fungal mycelia during spouting. Increasing spouting frequency from 4-h intervals to 1-h intervals decreased protein and enzyme production. Other operating conditions critical to the fermentation include proper humidification to prevent drying of the substrate and control of reactor wall temperature to prevent excessive condensation, which would interfere with proper spouting. PMID:9694679

  3. Geochemical stability of phosphorus solids below septic system infiltration beds

    NASA Astrophysics Data System (ADS)

    Zurawsky, M. A.; Robertson, W. D.; Ptacek, C. J.; Schiff, S. L.

    2004-09-01

    Review of 10 mature septic system plumes in Ontario, revealed that phosphorus (P) attenuation commonly occurred close to the infiltration pipes, resulting in discrete narrow intervals enriched in P by a factor of 2-4 ( Wood, J.S.A. 1993. MSc thesis, Dept. Earth Sci., University of Waterloo, Waterloo, Ont.; Ground Water 36 (1995) 1000; J. Contam. Hydrol. 33 (1998) 405). Although these attenuation reactions appeared to be sustainable under present conditions, the potential for remobilization of this P mass, should geochemical conditions change, is unknown. To test the stability of these P solids, dynamic flow column tests were carried out using sediments from three of the previously studied sites (Cambridge, Langton and Muskoka) focusing on sediments from the 'High-P' and underlying (Below) zones. Tests were continued for 166-266 pore volumes (PVs), during which time varying degrees of water saturation were maintained. During saturated flow conditions, relatively high concentrations of PO 4 were eluted from the Cambridge and Langton High-P zones (up to 4 and 9 mg/l P, respectively), accompanied by elevated concentrations of Fe (up to 1.4 mg/l) and Mn (up to 4 mg/l) and lower values of Eh (<150 mV). The Below zones from Cambridge and Langton, however, maintained lower concentrations of P (generally<2 mg/l), Fe (<0.2 mg/l) and Mn (<1 mg/l) and maintained higher Eh (>250 mV) during saturated flow conditions. During unsaturated flow, P and Fe declined dramatically in the High-P zones (P<1 mg/l, Fe<0.2 mg/l), whereas concentrations remained about the same during saturated and unsaturated flow in the Below zones. This behavior is at least partly attributed to the development of reducing conditions during saturated flow in the High-P zones, leading to reductive dissolution of Fe (III)-P solids present in the sediments. Reducing conditions did not develop in the Below zones apparently because of lower sediment organic carbon (OC) contents (0.03-0.04 wt.%) compared to the

  4. Geochemical stability of phosphorus solids below septic system infiltration beds.

    PubMed

    Zurawsky, M A; Robertson, W D; Ptacek, C J; Schiff, S L

    2004-09-01

    Review of 10 mature septic system plumes in Ontario, revealed that phosphorus (P) attenuation commonly occurred close to the infiltration pipes, resulting in discrete narrow intervals enriched in P by a factor of 2-4 (. MSc thesis, Dept. Earth Sci., University of Waterloo, Waterloo, Ont.; Ground Water 36 (1995) 1000; J. Contam. Hydrol. 33 (1998) 405). Although these attenuation reactions appeared to be sustainable under present conditions, the potential for remobilization of this P mass, should geochemical conditions change, is unknown. To test the stability of these P solids, dynamic flow column tests were carried out using sediments from three of the previously studied sites (Cambridge, Langton and Muskoka) focusing on sediments from the 'High-P' and underlying (Below) zones. Tests were continued for 166-266 pore volumes (PVs), during which time varying degrees of water saturation were maintained. During saturated flow conditions, relatively high concentrations of PO4 were eluted from the Cambridge and Langton High-P zones (up to 4 and 9 mg/l P, respectively), accompanied by elevated concentrations of Fe (up to 1.4 mg/l) and Mn (up to 4 mg/l) and lower values of Eh (<150 mV). The Below zones from Cambridge and Langton, however, maintained lower concentrations of P (generally<2 mg/l), Fe (<0.2 mg/l) and Mn (<1 mg/l) and maintained higher Eh (>250 mV) during saturated flow conditions. During unsaturated flow, P and Fe declined dramatically in the High-P zones (P<1 mg/l, Fe<0.2 mg/l), whereas concentrations remained about the same during saturated and unsaturated flow in the Below zones. This behavior is at least partly attributed to the development of reducing conditions during saturated flow in the High-P zones, leading to reductive dissolution of Fe (III)-P solids present in the sediments. Reducing conditions did not develop in the Below zones apparently because of lower sediment organic carbon (OC) contents (0.03-0.04 wt.%) compared to the High-P zones (0

  5. An Assessment of the Role of Solid Rocket Motors in the Generation of Orbital Debris

    NASA Technical Reports Server (NTRS)

    Mulrooney, Mark

    2004-01-01

    Through an intensive collection and assimilation effort of Solid Rocket Motor (SRM) related data and resources, the author offers a resolution to the uncertainties surrounding SRM particulate generation, sufficiently so to enable a first-order incorporation of SRMs as a source term in space debris environment definition. The following five key conclusions are derived: 1) the emission of particles in the size regime of greatest concern from an orbital debris hazard perspective (D > 100 micron), and in significant quantities, occurs only during the Tail-off phase of SRM burn activity, 2) the velocity of these emissions is correspondingly small - between 0 and 100 m/s, 3) the total Tail-off emitted mass is between approximately 0.04 and 0.65% of the initial propellant mass, 4) the majority of Tail-off emissions occur during the 30 second period that begins as the chamber pressure declines below approximately 34.5 kPa (5 psia) and 5) the size distribution for the emitted particles ranges from 100 micron

  6. Time-series analysis on bed morphology affected by debris flows along a headwater steep channel in Ohya-kuzure landslide, central Japan

    NASA Astrophysics Data System (ADS)

    Hayakawa, Y. S.; Imaizumi, F.; Hotta, N.; Tsunetaka, H.

    2013-12-01

    Deformation of steep terrain has been occurring since the formation of Ohyakuzure landslide in 1707. Although erosion controls in recent decades have resulted in vegetation recovery in downstream portions of the landslide terrain, hillslope erosion and debris flows frequently occur in uppermost steep subwatersheds in the landslide area to yield vast amount of sediment downstream. Ichino-sawa subwatershed in the landslide terrain, where detailed monitoring of debris flows and related topographic changes have previously been performed, has particularly steep slopes, and geomorphic processes therein have been quite active. Freeze-thaw weathering of fractured bedrock on hillslopes made of shale and sandstone frequently occurs in winter to spring season, and resultant sediment particles are provided into channel beds, which act as a source of debris flows that frequently occurs in summer season with heavy or accumulated rainfalls. High-resolution assessment of erosion/deposition patterns in channel bed of the Ichinosawa catchment was performed using multi-temporal terrestrial laser scanning data covering 3 seasons for 2 years. Seasonal changes in spatial distribution of erosion and deposition in the channel bed is quantified using a 0.1-m DEM converted from the original point cloud by TLS. The multi-temporal datasets provides an estimate of annual sediment storage and yield on the order of 1,000 - 5,000 m3. Analysis of changes in elevation by transverse and longitudinal profiles shows contrasting patterns of erosion and deposition along the studied reach: in particular, changes in bed elevation is found to be less in a 50-m long reach, whose downstream part seems bounded by valley narrowing and a knickpoint. Several topographic metrics, including stream gradient, surface roughness and topographic openness, were examined to estimate the characteristics of differing transport processes induced by debris flows along the reaches.

  7. Short communication: Environmental mastitis pathogen counts in freestalls bedded with composted and fresh recycled manure solids.

    PubMed

    Cole, K J; Hogan, J S

    2016-02-01

    An experiment was conducted to compare bacterial counts of environmental mastitis pathogens in composted recycled manure solids bedding with those in fresh recycled manure solids. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 freestalls included mattresses and was bedded weekly with composted recycled manure solids. The second row of 9 freestalls included mattresses and was bedded weekly with fresh recycled manure solids. The back one-third of stalls toward the alleyway was covered in 25 to 50 mm of bedding. Samples were taken from the back one-third of 4 stalls for both treatments on d 0, 1, 2, and 6 of each week. After 3 wk, bedding treatments were switched between rows, making the total duration 6 wk. Mean total gram-negative bacterial counts were approximately 0.5 log10 cfu/g of dry matter lower in the composted recycled manure solids on d 0 compared with fresh recycled manure solids. Klebsiella species, coliform, and Streptococcus species counts were at least 1.0 log10 cfu/g of dry matter lower in composted compared with fresh recycled manure solids on d 0. Only gram-negative bacterial counts on d 1 were reduced in composted recycled manure solids compared with fresh recycled manure solids. Differences were not observed between treatments in gram-negative bacterial, coliform, Klebsiella species, or Streptococcus species counts on d 2 and 6. Ash content was higher in composted recycled manure solids compared with fresh recycled manure solids on d 0, 1, 2, and 6. Despite the increase in ash after composting, bacterial counts of mastitis pathogens in composted recycled manure solids were comparable with those in fresh recycled manure when used as freestall bedding. PMID:26709164

  8. Improvement of continuous solid circulation rate measurement in a cold flow circulating fluidized bed

    SciTech Connect

    Ludlow, J.C.; Monazam, E.R.; Shadle, L.J.

    2008-03-10

    A method is described to independently estimate the solids velocity and voidage in the moving bed portion of the NETL circulating fluidized bed (CFB). These quantities are used by a device that continuously measures the solids circulation rate. The device is based on the use of a rotating Spiral vane installed in the standpipe of a circulating fluid bed (CFB). Correlations were developed from transient experiments and steady state mass balance data to correct the solids velocity and solids fraction in the standpipe as a function of standpipe aeration rate. A set of statisticallydesigned experiments was used to establish the need for these corrections and to verify the accuracy of solid circulation rate measurements after correction. The differences between the original and corrected measurements were quantitatively compared.

  9. Evaluation of wall boundary condition parameters for gas-solids fluidized bed simulations

    SciTech Connect

    Li, Tingwen; Benyahia, Sofiane

    2013-10-01

    Wall boundary conditions for the solids phase have significant effects on numerical predictions of various gas-solids fluidized beds. Several models for the granular flow wall boundary condition are available in the open literature for numerical modeling of gas-solids flow. In this study, a model for specularity coefficient used in Johnson and Jackson boundary conditions by Li and Benyahia (AIChE Journal, 2012, 58, 2058-2068) is implemented in the open-source CFD code-MFIX. The variable specularity coefficient model provides a physical way to calculate the specularity coefficient needed by the partial-slip boundary conditions for the solids phase. Through a series of 2-D numerical simulations of bubbling fluidized bed and circulating fluidized bed riser, the model predicts qualitatively consistent trends to the previous studies. Furthermore, a quantitative comparison is conducted between numerical results of variable and constant specularity coefficients to investigate the effect of spatial and temporal variations in specularity coefficient.

  10. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    NASA Astrophysics Data System (ADS)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    In the upper, wider reaches of Alpine valleys, shaping of active channels is usually subject to rapid change. It mostly depends upon hydro-climatic variability, runoff concentration and sediment supply, and may result in alternating sequences of fluvial and debris-flow pulses, as recorded in alluvial fans and terraces. Our study, carried in the frame of SAMCO (ANR) project, focuses on the upper Guil River Valley (Queyras, Southern French Alps) cut into the slaty shale "schistes lustrés". Steep, lower order drains carry a contrasted solid discharge, including predominantly sandy-loam particles mixed with gravels and boulders (sandstone schists, ophiolites). Abundant sediment supply by frost shattering, snow avalanche and landslides is then reworked during snowmelt or summer storm runoff events, and may result in catastrophic, very destructive floods along the main channel, as shown by historical records. Following the RI-30 year 2000 flood, our investigations included sediment budgets, i.e. balance of erosion and deposition, and the mapping of the source, transport and storage of various sediments (talus, colluvium, torrential fans, terraces). To better assess sediment fluxes and sediment delivery into the main channel network, we implemented tracers (pit-tags) in selected sub-catchments, significantly contributing to the sediment yield of the valley bottoms during the floods and/or avalanches: Maloqueste, Combe Morel, Bouchouse and Peyronnelle catchments. The first three are direct tributaries of the Guil River whereas the Peyronnelle is a left bank tributary of the Peynin River, which joins the Guil River via an alluvial cone with high human and material stakes. The Maloqueste and the Combe Morel are two tributaries facing each other in the Guil valley, representing a double lateral constraint for the road during flood events of the Guil River. After pit-tag initialisation in laboratory, we set them up along the four tributaries: Maloqueste (20 pit-tags), Combe

  11. SOLID PHASE MICROEXTRACTION SAMPLING OF FIRE DEBRIS RESIDUES IN THE PRESENCE OF RADIONUCLIDE SURROGATE METALS

    SciTech Connect

    Duff, M; Keisha Martin, K; S Crump, S

    2007-03-23

    The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating highly radioactive fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of FD residue from radionuclide metals involves using solid phase microextraction (SPME) fibers to remove the residues of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most (radioactive) metals. The focus of this research was to develop an examination protocol that was applicable to safe work in facilities where high radiation doses are shielded from the workers (as in radioactive shielded cells or ''hot cells''). We also examined the affinity of stable radionuclide surrogate metals (Co, Ir, Re, Ni, Ba, Cs, Nb, Zr and Nd) for sorption by the SPME fibers. This was done under exposure conditions that favor the uptake of FD residues under conditions that will provide little contact between the SPME and the FD material (such as charred carpet or wood that contains commonly-used accelerants). Our results from mass spectrometric analyses indicate that SPME fibers show promise for use in the room temperature head space uptake of organic FD residue (namely, diesel fuel oil, kerosene, gasoline and paint thinner) with subsequent analysis by gas chromatography (GC) with mass spectrometric (MS) detection. No inorganic forms of ignitable fluids were included in this study.

  12. Hydrodynamics Studies in a Liquid Solid Circulating Fluidized Bed of Varying Liquid Viscosity

    NASA Astrophysics Data System (ADS)

    Nirmala, G. S.; Muruganandam, L.

    2013-09-01

    To design an industrial liquid solid circulating fluidized bed system properly, it is important that the hydrodynamics be studied first. So far investigations have been carried out in a liquid solid circulating fluidized bed (LSCFB) with tap water as the liquid phase. There is still limited understanding on how particles are circulated in LSCFB with viscous fluids. The aim of our work was to characterize the hydrodynamics in a LSCFB with varying viscosity. Experiments were conducted in a fluidized bed riser of 0.1 m diameter by 2.4 m height with different viscous liquids, to study its effects of operating parameters namely; primary velocity, secondary velocity, total velocity, on the hydrodynamics characteristics of the LSCFB in terms of solid holdup, solid circulation rate and particle velocity. Experiments were conducted using water and glycerol at different concentration. The solid particle resin of 0.5 mm diameter was used for the experiment. The results indicate that the solid hold up in the riser is axially uniform for viscous liquids and increases with increase in auxiliary velocity. The average solid holdup found to decrease with increase in total velocity and increases with increase in liquid viscosity as the critical transitional velocity decreases with the increase in viscosity. The solid circulation rate is found to increase with increase in total velocity and auxiliary velocity, and also increases with increasing viscosity.

  13. Evaluation of a headspace solid-phase microextraction method for the analysis of ignitable liquids in fire debris.

    PubMed

    Fettig, Ina; Krüger, Simone; Deubel, Jan H; Werrel, Martin; Raspe, Tina; Piechotta, Christian

    2014-05-01

    The chemical analysis of fire debris represents a crucial part in fire investigations to determine the cause of a fire. A headspace solid-phase microextraction (HS-SPME) procedure for the detection of ignitable liquids in fire debris using a fiber coated with a mixture of three different sorbent materials (Divinylbenzene/Carboxen/Polydimethylsiloxane, DVB/CAR/PDMS) is described. Gasoline and diesel fuel were spiked upon a preburnt matrix (wood charcoal), extracted and concentrated with HS-SPME and then analyzed with gas chromatography/mass spectrometry (GC/MS). The experimental conditions--extraction temperature, incubation and exposure time--were optimized. To assess the applicability of the method, fire debris samples were prepared in the smoke density chamber (SDC) and a controlled-atmosphere cone calorimeter. The developed methods were successfully applied to burnt particleboard and carpet samples. The results demonstrate that the procedure that has been developed here is suitable for detecting these ignitable liquids in highly burnt debris. PMID:24329005

  14. Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles

    SciTech Connect

    Choudhuri, Ahsan

    2013-06-30

    One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed

  15. Cultivation of microorganisms in an air-solid fluidized bed fermentor with agitators

    SciTech Connect

    Tanaka, M.; Kawaide, A.; Matsuno, R.

    1986-09-01

    The productivity of a cell mass of Saccharomyces cerevisiae and enzymes of Eupenicillium javanicum increased by cultivation in an air-solid fluidized bed fermentor with agitators. The usefulness of the apparatus for the fluidized bed culture was verified. The productivity of amylase and protease of the fungus by fluidized bed culture was twice as high as that by stationary culture, considering the dry weight of cells and the enzyme activity. Physiological properties of yeast cells were changed by the fludized bed culture; there was a decrease in the cell size of yeast and changes to the aerobic properties of the yeast cells resulting from excessive supply of oxygen with a high flowrate of air. 8 references.

  16. APPARATUS FOR SHORT TIME MEASUREMENTS IN A FIXED-BED, GAS/SOLID REACTOR

    EPA Science Inventory

    An apparatus for exposure of a solid to reactive process gas is described which makes possible short time (≥ 0.3 to 15 s) exposures in a fixed-bed reactor. Operating conditions for differential reaction with respect to the gas concentration and rapid quench for arresting hi...

  17. ENVIRONMENTAL ASSESSMENT OF SOLID RESIDUES FROM FLUIDIZED-BED FUEL PROCESSING

    EPA Science Inventory

    The report gives results of the first 15 months of an environmental assessment of solid residues generated by fluidized-bed combustion (FBC) of coal and gasification of oil. Included are a literature search, chemical and physical residue characterization, laboratory leaching stud...

  18. ENVIRONMENTAL ASSESMENT OF SOLID RESIDUES FROM FLUIDIZED-BED FUEL PROCESSING

    EPA Science Inventory

    The report gives results of a 2-year study of the environmental assessment of solid residues generated by fluidized-bed combustion (FBC) of coal and gasification of oil. Included are a literature search, chemical and physical residue characterization, laboratory leaching studies,...

  19. On the Superficial Gas Velocity in Deep Gas-Solid Fluidized Beds

    SciTech Connect

    Li, Tingwen; Grace, John; Shadle, Lawrence; Guenther, Chris

    2011-11-15

    The superficial gas velocity is one of the key parameters used to determine the flow hydrodynamics in gas–solids fluidized beds. However, the superficial velocity varies with height in practice, and there is no consistent basis for its specification. Different approaches to determine the superficial gas velocity in a deep gas–solids system are shown to cause difficulties in developing models and in comparing predictions with experimental results. In addition, the reference conditions for superficial gas velocity are important in modeling of deep gas–solids systems where there is a considerable pressure drop.

  20. Validation of a 2.5D CFD model for cylindrical gas–solids fluidized beds

    SciTech Connect

    Li, Tingwen

    2015-09-25

    The 2.5D model recently proposed by Li et al. (Li, T., Benyahia, S., Dietiker, J., Musser, J., and Sun, X., 2015. A 2.5D computational method to simulate cylindrical fluidized beds. Chemical Engineering Science. 123, 236-246.) was validated for two cylindrical gas-solids bubbling fluidized bed systems. Different types of particles tested under various flow conditions were simulated using the traditional 2D model and the 2.5D model. Detailed comparison against the experimental measurements on solid concentration and velocity were conducted. Comparing to the traditional Cartesian 2D flow simulation, the 2.5D model yielded better agreement with the experimental data especially for the solid velocity prediction in the column wall region.

  1. Remediation of heavy metal polluted sediment by suspension and solid-bed leaching: estimate of metal removal efficiency.

    PubMed

    Löser, Christian; Zehnsdorf, Andreas; Hoffmann, Petra; Seidel, Heinz

    2007-01-01

    Remediation of heavy metal polluted sediment by extracting the metals with sulfuric acid can be performed as follows: abiotic suspension leaching, microbial suspension leaching, abiotic solid-bed leaching, and microbial solid-bed leaching. Abiotic leaching means that the acid is directly added, while microbial leaching means that the acid is generated from sulfur by microbes (bioleaching). These four principles were compared to each other with special emphasis on the effectiveness of metal solubilization and metal removal by subsequent washing. Abiotic suspension leaching was fastest, but suspending the solids exhibits some disadvantages (low solid content, costly reactors, permanent input of energy, high water consumption, special equipment required for solid separation, large amounts of waste water, sediment properties hinder reuse), which prevent suspension leaching in practice. Abiotic solid-bed leaching implies the supply of acid by percolating water which proceeds slowly due to a limited bed permeability. Microbial solid-bed leaching means the generation of acid within the bed and has been proven to be the only principle applicable to practice. Metal removal from leached sediment requires washing with water. Washing of solid beds was much more effective than washing of suspended sediment. The kinetics of metal removal from solid beds 0.3, 0.6 or 1.2m in height were similar; when using a percolation flow of 20lm(-2)h(-1), the removal of 98% of the mobile metals lasted 57-61h and required 8.5, 4.2 or 2.3lkg(-1) water. This means, the higher the solid bed, the lower the sediment-mass-specific demand for time and water. PMID:16908047

  2. Solid state track recorder neutron dosimetry measurements for fuel debris assessment of TMI-2 demineralizer-A

    SciTech Connect

    Ruddy, F.H.; Roberts, J.H.; Gold, R.; Preston, C.C.; Ulseth, J.A.

    1982-12-01

    Solid State Track Recorder (SSTR) neutron dosimetry measurements have been made in TMI-2 makeup Demineralizer A Cubicle in order to assess the amount of fuel debris present by means of the specific neutron activity of TMI-2 fuel. Based on recent calibration data and the results of the TMI-2 SSTR neutron dosimetry, the amount of fuel present is estimated to be 1.7 +- 0.6 kg. This value is in excellent agreement with a value determined independently by Compton recoil gamma-ray spectrometry. Sources of uncertainty in and proposed refinements of the present SSTR measurements are discussed.

  3. Interpretation of the XR2-1 experiment and characteristics of the BWR lower plenum debris bed

    SciTech Connect

    Hodge, S.A.; Ott, L.J.

    1997-11-01

    The Ex-Reactor (XR) experiments have been conducted to advance the understanding of BWR severe accident melt progression events. The XR2-1 experiment addresses the fate of the initial large (code-predicted) movements of molten metals from the upper core to the lower core and core plate region. For this question, which has ramifications for blockage formation in the core region, the XR2-1 test results provide significant and perhaps definitive insights. Nevertheless, some events that occurred during this test are creatures of the special features of the test apparatus, and there is a potential for misconceptions with respect to the direct applicability of some of the results. This paper describes the conclusions that can be drawn from the XR2-1 experiment results and identifies those areas (such as fuel pellet stack collapse and core plate integrity) where care must be taken not to misconstrue the test events. Another important area where much recent work has been performed is the effort to analyze the potential for maintaining core debris within the reactor vessel lower plenum by cooling of the outer vessel wall. One of the first steps in such an analytical endeavor is to attempt to establish the pattern of energy transfers into the wall inner surface. As a prerequisite to determination of this pattern, it is necessary to first consider the nature of the debris within the lower plenum. Too often is an easily represented homogeneous circulating liquid pool incorporated without adequate consideration of the true material conditions. Basic considerations of the relative quantities of materials present, the potentials for eutectics formations, and the associated melting points dictate otherwise. This paper offers some insights as to the true nature of the lower plenum debris and discusses the need for some relatively simple experiments that would contribute much toward the basic understanding necessary for accurate debris characterization. 11 refs., 4 figs., 4 tabs.

  4. Local CFD kinetic model of cadmium vaporization during fluid bed incineration of municipal solid waste.

    PubMed

    Soria, J; Gauthier, D; Falcoz, Q; Flamant, G; Mazza, G

    2013-03-15

    The emissions of heavy metals during incineration of Municipal Solid Waste (MSW) are a major issue to health and the environment. It is then necessary to well quantify these emissions in order to accomplish an adequate control and prevent the heavy metals from leaving the stacks. In this study the kinetic behavior of Cadmium during Fluidized Bed Incineration (FBI) of artificial MSW pellets, for bed temperatures ranging from 923 to 1073 K, was modeled. FLUENT 12.1.4 was used as the modeling framework for the simulations and implemented together with a complete set of user-defined functions (UDFs). The CFD model combines the combustion of a single solid waste particle with heavy metal (HM) vaporization from the burning particle, and it takes also into account both pyrolysis and volatiles' combustion. A kinetic rate law for the Cd release, derived from the CFD thermal analysis of the combusting particle, is proposed. The simulation results are compared with experimental data obtained in a lab-scale fluidized bed incinerator reported in literature, and with the predicted values from a particulate non-isothermal model, formerly developed by the authors. The comparison shows that the proposed CFD model represents very well the evolution of the HM release for the considered range of bed temperature. PMID:23410804

  5. Validation of a 2.5D CFD model for cylindrical gas–solids fluidized beds

    DOE PAGESBeta

    Li, Tingwen

    2015-09-25

    The 2.5D model recently proposed by Li et al. (Li, T., Benyahia, S., Dietiker, J., Musser, J., and Sun, X., 2015. A 2.5D computational method to simulate cylindrical fluidized beds. Chemical Engineering Science. 123, 236-246.) was validated for two cylindrical gas-solids bubbling fluidized bed systems. Different types of particles tested under various flow conditions were simulated using the traditional 2D model and the 2.5D model. Detailed comparison against the experimental measurements on solid concentration and velocity were conducted. Comparing to the traditional Cartesian 2D flow simulation, the 2.5D model yielded better agreement with the experimental data especially for the solidmore » velocity prediction in the column wall region.« less

  6. Phase shift method to estimate solids circulation rate in circulating fluidized beds

    SciTech Connect

    Ludlow, James Christopher; Panday, Rupen; Shadle, Lawrence J.

    2013-01-01

    While solids circulation rate is a critical design and control parameter in circulating fluidized bed (CFB) reactor systems, there are no available techniques to measure it directly at conditions of industrial interest. Cold flow tests have been conducted at NETL in an industrial scale CFB unit where the solids flow has been the topic of research in order to develop an independent method which could be applied to CFBs operating under the erosive and corrosive high temperatures and pressures of a coal fired boiler or gasifier. The dynamic responses of the CFB loop to modest modulated aeration flows in the return leg or standpipe were imposed to establish a periodic response in the unit without causing upset in the process performance. The resulting periodic behavior could then be analyzed with a dynamic model and the average solids circulation rate could be established. This method was applied to the CFB unit operated under a wide range of operating conditions including fast fluidization, core annular flow, dilute and dense transport, and dense suspension upflow. In addition, the system was operated in both low and high total solids inventories to explore the influence of inventory limiting cases on the estimated results. The technique was able to estimate the solids circulation rate for all transport circulating fluidized beds when operating above upper transport velocity, U{sub tr2}. For CFB operating in the fast fluidized bed regime (i.e., U{sub g}< U{sub tr2}), the phase shift technique was not successful. The riser pressure drop becomes independent of the solids circulation rate and the mass flow rate out of the riser does not show modulated behavior even when the riser pressure drop does.

  7. SUPERFUND TREATABILITY CLEARINGHOUSE: BDAT TREATABILITY DATA FOR SOILS, SLUDGES AND DEBRIS FROM THE CIRCULATING BED COMBUSTION (CBC) PROCESS

    EPA Science Inventory

    The two papers provide a general overview of the Ogden circulating bed combustion and summary data of both PCB laden soils for EPA-TSCA and a test on RCRA liquid organic wastes for the California Air Resources Board (CARB). This abstract will discuss the results of the PCB...

  8. (abstract) Development of Sorbent Bed Assembly for a Periodic 10K Solid Hydrogen Cryocooler

    NASA Technical Reports Server (NTRS)

    Wade, L. A.; Bowman, R. C., Jr.; Gilkinson, D. R.; Sywulka, P. H.

    1993-01-01

    A closed-cycle 10K sorption cryocooler is being fabricated for microgravity testing during a future space shuttle mission. A critical component of this cryogenic refrigerator is the metal hydride sorbent bed assembly (SBA). The SBA uses hydrides which absorb hydrogen gas at low pressure, (i.e., about 0.25 MPa from liquid hydrogen at 25K and below 0.2 kPa from solid hydrogen near 10K) and subsequently delivers hydrogen at nearly 10 MPa to a storage reservoir to repeat the Joule-Thomson (J-T) expansion process. The SBA includes three independent hydride beds where two contain LaNi(sub 4.8)Sn(sub 0.2) alloy and the third ZrNi. Detailed descriptions will be given for the three beds, which have specialized design features to enhance performance at each step of operation. In particular, two beds must rapidly absorb hydrogen in order for the J-T cold stage to reach 10K within two minutes from a 65K holding temperature. Performance characterization results will be compared to model analyses of the SBA.

  9. The study of solid circulation rate in a compartmented fluidized bed gasifier (CFBG)

    NASA Astrophysics Data System (ADS)

    Wee, S. K.; Pok, Y. W.; Law, M. C.; Lee, V. C. C.

    2016-06-01

    Biomass waste has been abundantly available in Malaysia since the booming of palm oil industry. In order to tackle this issue, gasification is seen a promising technology to convert waste into energy. In view of the heat requirement for endothermic gasification reaction as well as the complex design and operation of multiple fluidized beds, compartmented fluidized bed gasifier (CFBG) with the combustor and the gasifier as separate compartments is proposed. As such, solid circulation rate (SCR) is one of the essential parameters for steady gasification and combustion to be realized in their respective compartments. Experimental and numerical studies (CFD) on the effect of static bed height, main bed aeration, riser aeration and v-valve aeration on SCR have been conducted in a cold- flow CFBG model with only river sand as the fluidizing medium. At lower operating range, the numerical simulations under-predict the SCR as compared to that of the experimental results. Also, it predicts slightly different trends over the range. On the other hand, at higher operating range, the numerical simulations are able to capture those trends as observed in the experimental results at the lower operating range. Overall, the numerical results compare reasonably well with that of the experimental works.

  10. Fundamental study on transient bubble (slug) behavior by characterizing transient forces of solid particles in fluidized beds

    SciTech Connect

    Kono, H.O.

    1991-01-01

    The objective of this work is to recognize and interpret the signals of transient motion of bubbles (slugs) in fluidized beds by measuring and utilizing the signals of transient motion of solid particles. The two signals were measured simultaneously and also synchronized by using the TTL signal technique in the same fluidized beds. Also, a simultaneous study of video bubble image, transient force and pressure signals was initiated in a two dimensional fluidized bed. we successfully synchronized three signals so that the relationship of bubble behavior and force pressure signals can be identified and characterized. It has been found that bubble image can well be correlated to the transient force signal of solid particles under certain conditions in three dimensional fluidized beds. Accordingly, it seems that the transient force signals can significantly help understanding the transient motion of bubbles (slugs), which is important to design the fluidized beds.

  11. Fundamental study on transient bubble (slug) behavior by characterizing transient forces of solid particles in fluidized beds. 1990 Annual report

    SciTech Connect

    Kono, H.O.

    1991-01-01

    The objective of this work is to recognize and interpret the signals of transient motion of bubbles (slugs) in fluidized beds by measuring and utilizing the signals of transient motion of solid particles. The two signals were measured simultaneously and also synchronized by using the TTL signal technique in the same fluidized beds. Also, a simultaneous study of video bubble image, transient force and pressure signals was initiated in a two dimensional fluidized bed. we successfully synchronized three signals so that the relationship of bubble behavior and force pressure signals can be identified and characterized. It has been found that bubble image can well be correlated to the transient force signal of solid particles under certain conditions in three dimensional fluidized beds. Accordingly, it seems that the transient force signals can significantly help understanding the transient motion of bubbles (slugs), which is important to design the fluidized beds.

  12. Modeling debris-covered glaciers: response to steady debris deposition

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Anderson, Robert S.

    2016-05-01

    Debris-covered glaciers are common in rapidly eroding alpine landscapes. When thicker than a few centimeters, surface debris suppresses melt rates. If continuous debris cover is present, ablation rates can be significantly reduced leading to increases in glacier length. In order to quantify feedbacks in the debris-glacier-climate system, we developed a 2-D long-valley numerical glacier model that includes englacial and supraglacial debris advection. We ran 120 simulations on a linear bed profile in which a hypothetical steady state debris-free glacier responds to a step increase of surface debris deposition. Simulated glaciers advance to steady states in which ice accumulation equals ice ablation, and debris input equals debris loss from the glacier terminus. Our model and parameter selections can produce 2-fold increases in glacier length. Debris flux onto the glacier and the relationship between debris thickness and melt rate strongly control glacier length. Debris deposited near the equilibrium-line altitude, where ice discharge is high, results in the greatest glacier extension when other debris-related variables are held constant. Debris deposited near the equilibrium-line altitude re-emerges high in the ablation zone and therefore impacts melt rate over a greater fraction of the glacier surface. Continuous debris cover reduces ice discharge gradients, ice thickness gradients, and velocity gradients relative to initial debris-free glaciers. Debris-forced glacier extension decreases the ratio of accumulation zone to total glacier area (AAR). Our simulations reproduce the "general trends" between debris cover, AARs, and glacier surface velocity patterns from modern debris-covered glaciers. We provide a quantitative, theoretical foundation to interpret the effect of debris cover on the moraine record, and to assess the effects of climate change on debris-covered glaciers.

  13. Summary of Blast Shield and Material Testing for Development of Solid Debris Collection at the National Ignition Facility (NIF)

    SciTech Connect

    Shaughnessy, D A; Gostic, J M; Moody, K J; Grant, P M; Lewis, L A; Hutcheon, I D

    2011-11-21

    The ability to collect solid debris from the target chamber following a NIF shot has application for both capsule diagnostics, particularly for fuel-ablator mix, and measuring cross sections relevant to the Stockpile Stewardship program and nuclear astrophysics. Simulations have shown that doping the capsule with up to 10{sup 15} atoms of an impurity not otherwise found in the capsule does not affect its performance. The dopant is an element that will undergo nuclear activations during the NIF implosion, forming radioactive species that can be collected and measured after extraction from the target chamber. For diagnostics, deuteron or alpha induced reactions can be used to probe the fuel-ablator mix. For measuring neutron cross sections, the dopant should be something that is sensitive to the 14 MeV neutrons produced through the fusion of deuterium and tritium. Developing the collector is a challenge due to the extreme environment of the NIF chamber. The collector surface is exposed to a large photon flux from x-rays and unconverted laser light before it is exposed to a debris wind that is formed from vaporized material from the target chamber center. The photons will ablate the collector surface to some extent, possibly impeding the debris from reaching the collector and sticking. In addition, the collector itself must be mechanically strong enough to withstand the large amount of energy it will be exposed to, and it should be something that will be easy to count and chemically process. In order to select the best material for the collector, a variety of different metals have been tested in the NIF chamber. They were exposed to high-energy laser shots in order to evaluate their postshot surface characterization, morphology, degree of melt, and their ability to retain debris from the chamber center. The first set of samples consisted of 1 mm thick pieces of aluminum that had been fielded in the chamber as blast shields protecting the neutron activation diagnostic

  14. Erosion of steepland valleys by debris flows

    USGS Publications Warehouse

    Stock, J.D.; Dietrich, W.E.

    2006-01-01

    Episodic debris flows scour the rock beds of many steepland valleys. Along recent debris-flow runout paths in the western United States, we have observed evidence for bedrock lowering, primarily by the impact of large particles entrained in debris flows. This evidence may persist to the point at which debris-flow deposition occurs, commonly at slopes of less than ???0.03-0.10. We find that debris-flow-scoured valleys have a topographic signature that is fundamentally different from that predicted by bedrock river-incision models. Much of this difference results from the fact that local valley slope shows a tendency to decrease abruptly downstream of tributaries that contribute throughgoing debris flows. The degree of weathering of valley floor bedrock may also decrease abruptly downstream of such junctions. On the basis of these observations, we hypothesize that valley slope is adjusted to the long-term frequency of debris flows, and that valleys scoured by debris flows should not be modeled using conventional bedrock river-incision laws. We use field observations to justify one possible debris-flow incision model, whose lowering rate is proportional to the integral of solid inertial normal stresses from particle impacts along the flow and the number of upvalley debris-flow sources. The model predicts that increases in incision rate caused by increases in flow event frequency and length (as flows gain material) downvalley are balanced by rate reductions from reduced inertial normal stress at lower slopes, and stronger, less weathered bedrock. These adjustments lead to a spatially uniform lowering rate. Although the proposed expression leads to equilibrium long-profiles with the correct topographic signature, the crudeness with which the debris-flow dynamics are parameterized reveals that we are far from a validated debris-flow incision law. However, the vast extent of steepland valley networks above slopes of ???0.03-0.10 illustrates the need to understand debris

  15. Distinctive features of burning of a solid biofuel in a cyclone-bed furnace

    NASA Astrophysics Data System (ADS)

    Pitsukha, E. A.; Teplitskii, Yu. S.; Borodulya, V. A.

    2012-09-01

    A study has been made of the distinctive features of burning of a solid biofuel (wood, peat) in a cyclone-bed furnace. The limiting values of the moisture of wood chips as received and of the mass content of milled peat in the chip-milled peat mixture, at which the regime of its combustion is unstable, have been found. The temperature, velocity, and pressure distribution in the indicated furnace have been established. The dependences of the concentration of carbon and nitrogen monoxides on the excess air in exhaust gases in burning lump wood and crushed peat briquettes have been established.

  16. Coolability of UO2 debris beds in pressurized water pools: DCC-1 and DCC-2 experiment results

    SciTech Connect

    Reed, A.W.; Bergeron, E.D.; Boldt, K.R.; Schmidt, T.R.

    1984-09-01

    DCC-1 and DCC-2 (Degraded Core Coolability) have provided the first in-pile data for water-urania dryout heat flux and quench behavior. DCC-1, designed to test the laminar flow region of dryout, has displayed unexpected results. while the dryout fluxes at one atmosphere are approximately those predicted by many of the models, the pressure dependence of the dryout data is predicted by none of the models. The quench behavior of DCC-1 displays none of the fingering observed in out-of-pile experiments. The quench times extend for hours. The DCC-2 dryout data conforms in magnitude and pressure dependence with several of the models. In addition to global dryouts, in which the dry zone extends across the width of the bed, local dryouts were observed. These are zones of lower than average permeability which dry out and achieve stable temperatures without eliminating coolant flow to the bottom of the bed. The quench times in DCC-2 are only a few minutes long. Fingering, modified by the radially varying temperature of the dry particles, was observed.

  17. Coolability of UO/sub 2/ debris beds in pressurized water pools: DCC-1 and DCC-2 experiment results. Revision

    SciTech Connect

    Reed, A.W.; Bergeron, E.D.; Boldt, K.R.; Schmidt, T.R.

    1984-01-01

    DCC-1 and DCC-2 have provided the first in-pile data for water-urania dryout heat flux and quench behavior. DCC-1, designed to test the laminar flow region of dryout, has displayed unexpected results. While the dryout fluxes at one atmosphere are approximately those predicted by many of the models, the pressure dependence of the dryout data is predicted by none of the models. The quench behavior of DCC-1 displays none of the fingering observed in out-of-pile experiments. The quench times extend for hours. The DCC-2 dryout data conform in magnitude and pressure dependence with several of the models. In addition to global dryouts, in which the dry zone extends across the width of the bed, local dryouts were observed. These are zones of lower than average permeability which dry out and achieve stable temperatures without eliminating coolant flow to the bottom of the bed. The quench times in DCC-2 are only a few minutes long. Fingering, modified by the radially varying temperature of the dry particles, was observed.

  18. Solids circulation around a jet in a fluidized bed gasifier. Final technical report, September 1, 1978-September 30, 1980

    SciTech Connect

    Gidaspow, D.; Ettehadieh, B.; Lin, C.; Goyal, A.; Lyczkowski, R.W.

    1980-01-01

    The object of this investigation was to develop an experimentally verified hydrodynamic model to predict solids circulation around a jet in a fluidized bed gasifier. Hydrodynamic models of fluidization use the principles of conservation of mass, momentum and energy. To account for unequal velocities of solid and fluid phases, separate phase momentum balances are developed. Other fluid bed models used in the scale-up of gasifiers do not employ the principles of conservation of momentum. Therefore, these models cannot predict fluid and particle motion. In such models solids mixing is described by means of empirical transfer coefficients. A two dimensional unsteady state computer code was developed to give gas and solid velocities, void fractions and pressure in a fluid bed with a jet. The growth, propagation and collapse of bubbles was calculated. Time-averaged void fractions were calculated that showed an agreement with void fractions measured with a gamma ray densitometer. Calculated gas and solid velocities in the jet appeared to be reasonable. Pressure and void oscillations also appear to be reasonable. A simple analytical formula for the rate of solids circulation was developed from the equations of change. It agrees with Westinghouse fluidization data in a bed with a draft tube. One dimensional hydrodynamic models were applied to modeling of entrained-flow coal gasification reactors and compared with data. Further development of the hydrodynamic models should make the scale-up and simulation of fluidized bed reactors a reality.

  19. Combustion of municipal solid wastes with oil shale in a circulating fluidized bed. Final report

    SciTech Connect

    1996-06-30

    The problem addressed by our invention is that of municipal solid waste utilization. The dimensions of the problem can be visualized by the common comparison that the average individual in America creates in five years time an amount of solid waste equivalent in weight to the Statue of Liberty. The combustible portion of the more than 11 billion tons of solid waste (including municipal solid waste) produced in the United States each year, if converted into useful energy, could provide 32 quads per year of badly needed domestic energy, or more than one-third of our annual energy consumption. Conversion efficiency and many other factors make such a production level unrealistic, but it is clear that we are dealing with a very significant potential resource. This report describes research pertaining to the co-combustion of oil shale with solid municipal wastes in a circulating fluidized bed. The oil shale adds significant fuel content and also constituents that can possible produce a useful cementitious ash.

  20. Energy coupling in short pulse laser solid interactions and its impact for space debris removal.

    PubMed

    Neely, David; Allott, Ric; Bingham, Bob; Collier, John; Greenhalgh, Justin; Michaelis, Max; Phillips, Jonathan; Phipps, Claude R; McKenna, Paul

    2014-11-01

    Significant advances have been made over the last decade to improve the performance, efficiency, and contrast of high peak and average power laser systems, driven by their use in a wide variety of fields, from the industrial to the scientific. As the contrast of the lasers has improved, interactions with contrasts of 1012 are now routinely undertaken. At such high contrasts, there is negligible preplasma formation and the ionized surface layer created by subpicosecond-duration pulses typically forms a highly reflective "plasma mirror" capable of reflecting between 70% and 90% of the incident energy. Although such interactions are of significant interest for applications such as harmonic source production and to enable the underlying physics to be studied, their low absorption can limit their usefulness for applications such as space debris removal. PMID:25402936

  1. Biological nutrient removal from leachate using a pilot liquid-solid circulating fluidized bed bioreactor (LSCFB).

    PubMed

    Eldyasti, Ahmed; Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2010-09-15

    Biological treatment of landfill leachate is a concern due to toxicity, high ammonia, low biodegradable organic matter concentrations, and low carbon-to-nitrogen ratio. To study the reliability and commercial viability of leachate treatment using an integrated liquid-solid circulating fluidized bed bioreactor (LSCFB), a pilot-scale LSCFB was established at the Adelaide Pollution Control Plant, London, Ontario, Canada. Anoxic and aerobic columns were used to optimize carbon and nutrient removal capability from leachate using 600 microm lava rock with a total porosity of 61%, at empty bed contact times (EBCTs) of 0.55, 0.49, and 0.41 d. The LSCFB achieved COD, nitrogen, and phosphorus removal efficiencies of 85%, 80%, and 70%, respectively at a low carbon-to-nitrogen ratio of 3:1 and nutrients loading rates of 2.15 kg COD/(m(3) d), 0.70 kg N/(m(3) d), and 0.014 kg P/(m(3) d), as compared with 60-77% COD and 70-79% nitrogen removal efficiencies achieved by upflow anaerobic sludge blanket (UASB) and moving bed bioreactor (MBBR), respectively. The LSCFB effluent characterized by solids retention times (SRTs) of 31, 38 and 44 d. PMID:20510504

  2. Energy recovery from municipal solid waste and sewage sludge using multi-solid fluidized bed combustion technology

    NASA Astrophysics Data System (ADS)

    1981-07-01

    The concept is to recover energy as high and low pressure steam, simultaneously. High pressure steam would be generated from flue gas using a conventional tubular boiler. Low pressure steam would be generated by direct contact drying of DSS (as 4 percent solids) with hot sand in a fluidized bed that is an integral part of the MS-FBC process. It is proposed that high pressure steam could be used for district heating or electricity generation. The low pressure steam could be used for close proximity building heat. The results of the investigation show that the MS-FBC process concept for the co-utilization of MSW and DSS is technically feasible and that the thermal efficiency of the process is 76 to 82 percent based on experiments conducted in a 70 to 85 lb/h pilot plant and calculations on three conceptual cases.

  3. Debris Flows and Related Phenomena

    NASA Astrophysics Data System (ADS)

    Ancey, C.

    Torrential floods are a major natural hazard, claiming thousands of lives and millions of dollars in lost property each year in almost all mountain areas on the Earth. After a catastrophic eruption of Mount St. Helen in the USA in May 1980, water from melting snow, torrential rains from the eruption cloud, and water displaced from Spirit Lake mixed with deposited ash and debris to produce very large debris flows and cause extensive damage and loss of life [1]. During the 1985 eruption of Nevado del Ruiz in Colombia, more than 20,000 people perished when a large debris flow triggered by the rapid melting of snow and ice at the volcano summit, swept through the town of Armero [2]. In 1991, the eruption of Pinatubo volcano in the Philippines disperses more than 5 cubic kilometres of volcanic ash into surrounding valleys. Much of that sediment has subsequently been mobilised as debris flows by typhoon rains and has devastated more than 300 square kilometres of agricultural land. Even, in Eur opean countries, recent events that torrential floods may have very destructive effects (Sarno and Quindici in southern Italy in May 1998, where approximately 200 people were killed). The catastrophic character of these floods in mountainous watersheds is a consequence of significant transport of materials associated with water flows. Two limiting flow regimes can be distinguished. Bed load and suspension refer to dilute transport of sediments within water. This means that water is the main agent in the flow dynamics and that the particle concentration does not exceed a few percent. Such flows are typically two-phase flows. In contrast, debris flows are mas s movements of concentrated slurries of water, fine solids, rocks and boulders. As a first approximation, debris flows can be treated as one-phase flows and their flow properties can be studied using classical rheological methods. The study of debris flows is a very exciting albeit immature science, made up of disparate elements

  4. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD

    SciTech Connect

    Soria, José; Gauthier, Daniel; Flamant, Gilles; Rodriguez, Rosa; Mazza, Germán

    2015-09-15

    Highlights: • A CFD two-scale model is formulated to simulate heavy metal vaporization from waste incineration in fluidized beds. • MSW particle is modelled with the macroscopic particle model. • Influence of bed dynamics on HM vaporization is included. • CFD predicted results agree well with experimental data reported in literature. • This approach may be helpful for fluidized bed reactor modelling purposes. - Abstract: Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073 K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator.

  5. Data summary of municipal solid waste management alternatives. Volume 5, Appendix C, Fluidized-bed combustion

    SciTech Connect

    1992-10-01

    This appendix provides information on fluidized-bed combustion (FBC) technology as it has been applied to municipal waste combustion (MWC). A review of the literature was conducted to determine: (1) to what extent FBC technology has been applied to MWC, in terms of number and size of units was well as technology configuration; (2) the operating history of facilities employing FBC technology; and (3) the cost of these facilities as compared to conventional MSW installations. Where available in the literature, data on operating and performance characteristics are presented. Tabular comparisons of facility operating/cost data and emissions data have been complied and are presented. The literature review shows that FBC technology shows considerable promise in terms of providing improvements over conventional technology in areas such as NOx and acid gas control, and ash leachability. In addition, the most likely configuration to be applied to the first large scale FBC dedicated to municipal solid waste (MSW) will employ circulating bed (CFB) technology. Projected capital costs for the Robbins, Illinois 1600 ton per day CFB-based waste-to-energy facility are competitive with conventional systems, in the range of $125,000 per ton per day of MSW receiving capacity.

  6. Development and optimization of a solid dispersion hot-melt fluid bed coating method.

    PubMed

    Kennedy, J P; Niebergall, P J

    1996-04-01

    A new hot-melt fluid bed coating process has been developed, characterized, and optimized. Polyethylene glycol served as the model coating agent and was charged with substrate into the fluid bed chamber in the solid state. The processing stages included: (A) warm-up, (B) preheating, (C) melting-spreading, and (D) cooling-congealing. A central composite design was utilized to characterize and optimize the process. Substrate porosity and density evaluations were conducted by mercury intrusion. The method proved capable of coating nonpareils from 10 to 35 mesh (0.500 to 2.00 mm) and tablets up to 1 g. The nonpareils were coated as individual particles, while particle sizes significantly smaller than 40 mesh (0.420 mm) tended to agglomerate. The porosity and density values of dissimilar nonpareil batches showed a large degree of variation, affecting the method's reproducibility. Additive coatings were achieved by sequential runs using coating agents of diminishing melting points. The method is a viable alternative to hot-melt spray-coating processes. Organic solvents, spraying equipment, steam jackets, and/or heating tape are eliminated from the process. PMID:9552331

  7. Continuous protein recovery from whey using liquid-solid circulating fluidized bed ion-exchange extraction.

    PubMed

    Lan, Qingdao; Bassi, Amarjeet; Zhu, Jing-Xu Jesse; Margaritis, Argyrios

    2002-04-20

    A liquid-solid circulating fluidized bed (LSCFB) continuous ion-exchange extraction system has been investigated for total protein recovery from whey solutions under various operating conditions. The effectiveness of a dynamic seal was evaluated between the riser and the downcomer, and the best conditions for the establishment of this seal were established. Start-up studies indicated that the system is robust and stable. Under optimal conditions, a productivity of 8.2 g of total protein removed per hour per kilogram of resin was achieved with a protein removal efficiency of 78.4%. However, higher overall protein recovery of up to 90% was also achieved under other conditions, with lower protein concentration in the effluent and a lower overall productivity. PMID:11870606

  8. Prediction of Solids Circulation Rate of Cork Particles in an Ambient-Pressure Pilot-Scale Circulating Fluidized Bed

    SciTech Connect

    Huang, Yue; Turton, Richard; Famouri, Parviz; Boyle, Edward J.

    2009-01-07

    Circulating fluidized beds (CFB) are currently used in many industrial processes for noncatalytic and catalytic because its effective control is the key to smooth operation of a CFB system. This paper presents a method for solids flow metering from pressure drop measurements in the standpipe dense phase. A model based on the Ergun equation is developed to predict the solids flow rate and voidage in the dense phase of the standpipe. The profile of the solids flow rate under unsteady state is also presented. With the use of this method, the dynamic response time at different locations along the standpipe of a pilot-scale fluidized bed operating at ambient conditions with 812 mu m cork particles is estimated successfully. Through the use of a pressure balance analysis, solids flow models for the standpipe, riser, and other sections of the flow loop are combined to give an integrated CFB model.

  9. Mathematical modelling of particle mixing effect on the combustion of municipal solid wastes in a packed-bed furnace.

    PubMed

    Yang, Yao Bin; Swithenbank, Jim

    2008-01-01

    Packed bed combustion is still the most common way to burn municipal solid wastes. In this paper, a dispersion model for particle mixing, mainly caused by the movement of the grate in a moving-burning bed, has been proposed and transport equations for the continuity, momentum, species, and energy conservation are described. Particle-mixing coefficients obtained from model tests range from 2.0x10(-6) to 3.0x10(-5)m2/s. A numerical solution is sought to simulate the combustion behaviour of a full-scale 12-tonne-per-h waste incineration furnace at different levels of bed mixing. It is found that an increase in mixing causes a slight delay in the bed ignition but greatly enhances the combustion processes during the main combustion period in the bed. A medium-level mixing produces a combustion profile that is positioned more at the central part of the combustion chamber, and any leftover combustible gases (mainly CO) enter directly into the most intensive turbulence area created by the opposing secondary-air jets and thus are consumed quickly. Generally, the specific arrangement of the impinging secondary-air jets dumps most of the non-uniformity in temperature and CO into the gas flow coming from the bed-top, while medium-level mixing results in the lowest CO emission at the furnace exit and the highest combustion efficiency in the bed. PMID:17697769

  10. Selective mixed-bed solid phase extraction of atrazine herbicide from environmental water samples using molecularly imprinted polymer.

    PubMed

    Zarejousheghani, Mashaalah; Fiedler, Petra; Möder, Monika; Borsdorf, Helko

    2014-11-01

    A novel approach for the selective extraction of organic target compounds from water samples has been developed using a mixed-bed solid phase extraction (mixed-bed SPE) technique. The molecularly imprinted polymer (MIP) particles are embedded in a network of silica gel to form a stable uniform porous bed. The capabilities of this method are demonstrated using atrazine as a model compound. In comparison to conventional molecularly imprinted-solid phase extraction (MISPE), the proposed mixed-bed MISPE method in combination with gas chromatography-mass spectrometry (GC-MS) analysis enables more reproducible and efficient extraction performance. After optimization of operational parameters (polymerization conditions, bed matrix ingredients, polymer to silica gel ratio, pH of the sample solution, breakthrough volume plus washing and elution conditions), improved LODs (1.34 µg L(-1) in comparison to 2.25 µg L(-1) obtained using MISPE) and limits of quantification (4.5 µg L(-1) for mixed-bed MISPE and 7.5 µg L(-1) for MISPE) were observed for the analysis of atrazine. Furthermore, the relative standard deviations (RSDs) for atrazine at concentrations between 5 and 200 µg L(-1) ranged between 1.8% and 6.3% compared to MISPE (3.5-12.1%). Additionally, the column-to-column reproducibility for the mixed-bed MISPE was significantly improved to 16.1%, compared with 53% that was observed for MISPE. Due to the reduced bed-mass sorbent and at optimized conditions, the total amount of organic solvents required for conditioning, washing and elution steps reduced from more than 25 mL for conventional MISPE to less than 2 mL for mixed-bed MISPE. Besides reduced organic solvent consumption, total sample preparation time of the mixed-bed MISPE method relative to the conventional MISPE was reduced from more than 20 min to less than 10 min. The amount of organic solvent required for complete elution diminished from 3 mL (conventional MISPE) to less than 0.4 mL with the mixed-bed

  11. Design and analysis of a coupled solid oxide fuel cell and metal hydride bed system

    NASA Astrophysics Data System (ADS)

    Song, Ke

    Solid oxide fuel cells have exhibited excellent performance at high temperature for a few years. However, the fuel supply and the practical fuel cell application need to be improved especially for transportation or stand-alone facility usage. Two modified hydrogen storage models (two vessel and three vessel hydrogen storage system) are presented in this study. The gravimetric density and volumetric density are calculated in order to meet the DOE requirements. Furthermore, the time dependence model of hydrogen releasing in metal hydride bed (MHB) is built up. And the simulations are carried on in isothermal and adiabatic conditions. The simulation results indicate: the isothermal model can provide sufficient hydrogen flow until the MHB is emptied; the adiabatic model can only last short period because of the fast temperature decreasing in MHB. The steady state and time dependence model of coupled solid oxide fuel cells (SOFC) and MHB system are also investigated. The steady state model focuses on the heat recycle process for coupled system. The calculation shows the heat generated in system can provide enough energy for inner recycle. On the other hand, the time de-pendence model mainly concerns the time delay in such a coupled system. The simu-lation shows the time delay mainly comes from hydrogen feed.

  12. Thermal treatment of electronic waste in a fluidised bed and chemical digestion of solid products.

    PubMed

    Woynarowska, Amelia; Żukowski, Witold; Żelazny, Sylwester

    2016-07-01

    The article presents the results of e-waste thermal treatment in a fluidised bed reactor and solid products digestion under acidic conditions. During the processes, measurements of carbon monoxide, carbon dioxide, volatile organic compounds, nitrogen oxides, sulphur dioxide, hydrogen chloride, hydrogen bromide, hydrogen cyanide, ammonia, phenol, aliphatic and aromatic hydrocarbons, hydrogen fluoride and phosgene were carried out. Several digestion tests of the solid residue in sulphuric acid (VI) at 25 °C-65 °C, for 55 min-24 h were conducted. In each case, the dilution method was used, i.e. preliminary digestion in concentrated sulphuric acid (VI) (95%) for 40 min, and then dilution to expected concentrations (30%-50%). Most preferred results were obtained using sulphuric acid (VI) with a target concentration of 40% at 65 °C, where the leaching degrees were 76.56% for copper, 71.67% for iron, 91.89% for zinc and 97.40% for tin. The time necessary to effectively carry out the digestion process was 220 min. PMID:27245176

  13. Coupling scales for modelling heavy metal vaporization from municipal solid waste incineration in a fluid bed by CFD.

    PubMed

    Soria, José; Gauthier, Daniel; Flamant, Gilles; Rodriguez, Rosa; Mazza, Germán

    2015-09-01

    Municipal Solid Waste Incineration (MSWI) in fluidized bed is a very interesting technology mainly due to high combustion efficiency, great flexibility for treating several types of waste fuels and reduction in pollutants emitted with the flue gas. However, there is a great concern with respect to the fate of heavy metals (HM) contained in MSW and their environmental impact. In this study, a coupled two-scale CFD model was developed for MSWI in a bubbling fluidized bed. It presents an original scheme that combines a single particle model and a global fluidized bed model in order to represent the HM vaporization during MSW combustion. Two of the most representative HM (Cd and Pb) with bed temperatures ranging between 923 and 1073K have been considered. This new approach uses ANSYS FLUENT 14.0 as the modelling platform for the simulations along with a complete set of self-developed user-defined functions (UDFs). The simulation results are compared to the experimental data obtained previously by the research group in a lab-scale fluid bed incinerator. The comparison indicates that the proposed CFD model predicts well the evolution of the HM release for the bed temperatures analyzed. It shows that both bed temperature and bed dynamics have influence on the HM vaporization rate. It can be concluded that CFD is a rigorous tool that provides valuable information about HM vaporization and that the original two-scale simulation scheme adopted allows to better represent the actual particle behavior in a fluid bed incinerator. PMID:26050934

  14. A new model for two-dimensional numerical simulation of pseudo-2D gas-solids fluidized beds

    SciTech Connect

    Li, Tingwen; Zhang, Yongmin

    2013-10-11

    Pseudo-two dimensional (pseudo-2D) fluidized beds, for which the thickness of the system is much smaller than the other two dimensions, is widely used to perform fundamental studies on bubble behavior, solids mixing, or clustering phenomenon in different gas-solids fluidization systems. The abundant data from such experimental systems are very useful for numerical model development and validation. However, it has been reported that two-dimensional (2D) computational fluid dynamic (CFD) simulations of pseudo-2D gas-solids fluidized beds usually predict poor quantitative agreement with the experimental data, especially for the solids velocity field. In this paper, a new model is proposed to improve the 2D numerical simulations of pseudo-2D gas-solids fluidized beds by properly accounting for the frictional effect of the front and back walls. Two previously reported pseudo-2D experimental systems were simulated with this model. Compared to the traditional 2D simulations, significant improvements in the numerical predictions have been observed and the predicted results are in better agreement with the available experimental data.

  15. Fine and ultrafine particles generated during fluidized bed combustion of different solid fuels

    SciTech Connect

    Urciuolo, M.; Barone, A.; D'Alessio, A.; Chirone, R.

    2008-12-15

    The paper reports an experimental study carried out with a 110-mm ID fluidized bed combustor focused on the characterization of particulates formation/emission during combustion of coal and non-fossil solid fuels. Fuels included: a bituminous coal, a commercial predried and granulated sludge (GS), a refuse-derived fuel (RDF), and a biomass waste (pine seed shells). Stationary combustion experiments were carried out analyzing the fate of fuel ashes. Fly ashes collected at the combustor exhaust were characterized both in terms of particle size distribution and chemical composition, with respect to both trace and major elements. Tapping-Mode Atomic Force Microscopy (TM-AFM) technique and high-efficiency cyclone-type collector devices were used to characterize the size and morphology of the nanometric-and micronic-size fractions of fly ash emitted at the exhaust respectively. Results showed that during the combustion process: I) the size of the nanometric fraction ranges between 2 and 65 nm; ii) depending on the fuel tested, combustion-assisted attrition or the production of the primary ash particles originally present in the fuel particles, are responsible of fine particle generation. The amount in the fly ash of inorganic compounds is larger for the waste-derived fuels, reflecting the large inherent content of these compounds in the parent fuels.

  16. Fluidized-bed design for ICF reactor blankets using solid-lithium compounds

    SciTech Connect

    Sucov, E.W.; Malick, F.S.; Green, L.; Hall, B.O.

    1983-01-01

    A fluidized-bed concept for blankets of dry or wetted first-wall ICF reactors using solid-lithium compounds is described. The reaction chamber is a right cylinder, 32 m high and 20 m in diameter; the blanket is composed of 36 steel tanks, 32 m high, which carry the sintered Li/sub 2/O particles in the fluidizing helium gas. Each tank has a radial thickness of 2 m which generates a tritium breeding ration (TBR) of 1.27 and absorbs over 98% of the neutron energy; reducing the thickness to 1.2 m produces a TBR of 1.2 and energy absorption of 97% which satisfy the design goals. Calculations of tritium diffusion through the grains and heat removal from the grains showed that neither could be removed by the carrier gas; tritium and heat are therefore removed by removing the grains themselves by varying the helium flow rate. The particles are continuously fed into the bottom of the tanks at 300/sup 0/C and removed at the top at 475/sup 0/C. Tritium and heat extraction are easily and conveniently done outside the reactor.

  17. Residues characterisation from the fluidised bed combustion of East London's solid recovered fuel.

    PubMed

    Balampanis, D E; Pollard, S J T; Simms, N; Longhurst, P; Coulon, F; Villa, R

    2010-07-01

    Waste thermal treatment in Europe is moving towards the utilisation of the combustible output of mechanical, biological treatment (MBT) plants. The standardisation of solid recovered fuels (SRF) is expected to support this trend and increase the amount of the generated combustion residues. In this work, the residues and especially the fly ashes from the fluidised bed combustion (FBC) of East London's NCV 3, Cl 2, and Hg 1 class SRF, are characterised. The following toxicity indicators have been studied: leachable chlorine, organochlorides expressed as pentachlorobenzene and hexachlorobenzene, and the heavy metals Cu, Cr, Cd, Zn, Ni, and Pb. Furthermore the mineralogical pattern of the ashes has been studied by means of XRD and SEM-EDS. The results suggest that these SRF derived ashes have significantly lower quantities of Cu, Cd, Pb, Zn, leachable Cl, and organochlorides when compared to other literature values from traditional waste thermal treatment applications. This fact highlights the importance of modern separation technologies employed in MBT plants for the removal of components rich in metals and chlorine from the combustible output fraction of SRF resulting to less hazardous residues. PMID:20231082

  18. Availability of trace elements in solid waste from fluidized bed combustion of coal

    SciTech Connect

    Rope, S.K.; Jornitz, R.S.; Suhre, D.T.

    1987-12-01

    This report presents data on the inorganic constituents (major and trace elements) of coal and solid waste from a coal-fired facility on the Idaho National Engineering Laboratory (INEL) which uses the fluidized bed combustion process. Three factors were used to assess the potential environmental impacts of elements in coal waste: (1) the concentrations relative to those measured previously in surrounding soils of the INEL (the enrichment ratio); (2) the availability of elements from waste relative to soils; and (3) toxicity or essentiality to biota. Considering both enrichment and availability, Al, B, Be, Ca, Cr, Na, Mo, Se, Sr, and Ti are most likely to be affected in the local environment due to fly ash deposition and/or resuspension of FBC waste. Only B, Cr, Mo, and Se are likely to be of concern in terms of toxicity. The high concentrations of Cr and B in FBC waste are expected to be toxic to plants. Concentrations of Se and Mo present in FBC waste have been shown to produce levels in plants which can be toxic to herbivorous animals. 14 refs, 1 fig., 4 tabs.

  19. Vaporization of heavy metals during thermal treatment of model solid waste in a fluidized bed incinerator.

    PubMed

    Yu, Jie; Sun, Lushi; Xiang, Jun; Hu, Song; Su, Sheng; Qiu, Jianrong

    2012-03-01

    This paper investigated the volatilization behavior of heavy metals during thermal treatment of model solid waste in a fluidized bed reactor. Four metal chlorides (Cd, Pb, Cu and Zn) were chosen as metal sources. The influence of redox conditions, water and mineral matrice on heavy metal volatilization was investigated. In general, Cd shows significant vaporization especially when HCl was injected, while Cu and Pb vaporize moderately and Zn vaporization is negligible. Increasing oxygen concentration can lower heavy metal vaporization. Heavy metal interactions with the mineral matter can result in the formation of stable metallic species thus playing a negative effect on their behavior. However, HCl can promote the heavy metal release by preventing the formation of stable metallic species. The chemical sorption (either physical or chemical) inside the pores, coupled with the internal diffusion of gaseous metal species, may also control the vaporization process. With SO(2) injected, Cd and Pb show a higher volatility as a result of SO(2) reducing characteristics. From the analysis, the subsequent order of heavy metal volatility can be found: Cd>Cu≥Pb≫Zn. PMID:22264859

  20. Gasification behavior of carbon residue in bed solids of black liquor gasifier

    SciTech Connect

    Preto, Fernando; Zhang, Xiaojie; Wang, Jinsheng

    2008-07-15

    Steam gasification of carbon residue in bed solids of a low-temperature black liquor gasifier was studied using a thermogravimetric system at 3 bar. Complete gasification of the carbon residue, which remained unreactive at 600 C, was achieved in about 10 min as the temperature increased to 800 C. The rate of gasification and its temperature dependence were evaluated from the non-isothermal experiment results. Effects of particle size and adding H{sub 2} and CO to the gasification agent were also studied. The rate of steam gasification could be taken as zero order in carbon until 80% of carbon was gasified, and for the rest of the gasification process the rate appeared to be first order in carbon. The maximum rate of carbon conversion was around 0.003/s and the activation energy was estimated to be in the range of 230-300 kJ/mol. The particle size did not show significant effect on the rate of gasification. Hydrogen and carbon monoxide appeared to retard the onset of the gasification process. (author)

  1. Novel two-phase anaerobic gasification with solid-bed acid digestion in tandem with fixed-film methane fermentation

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Sajjad, A.

    1983-01-01

    The development and performance of a novel solid-bed two-phase anaerobic digestion system are described. The system consists of a bed of organic feed operated in tandem with an acid-phase slurry digester and a methane-phase upflow anaerobic filter. The bed and the acid-phase digesters liquefy and convert the organics to volatile fatty acids (VFA) without gas production, while a high methane-content product gas is collected from the methane-phase filter. With municipal refuse feeds, VFA and ethanol were the major products from acid-phase digestion. A high methane content (up to 88 mol %) gas was the major product from the methane phase filter.

  2. Fluid bed gasification – Plasma converter process generating energy from solid waste: Experimental assessment of sulphur species

    SciTech Connect

    Morrin, Shane; Lettieri, Paola; Chapman, Chris; Taylor, Richard

    2014-01-15

    Highlights: • We investigate gaseous sulphur species whilst gasifying sulphur-enriched wood pellets. • Experiments performed using a two stage fluid bed gasifier – plasma converter process. • Notable SO{sub 2} and relatively low COS levels were identified. • Oxygen-rich regions of the bed are believed to facilitate SO{sub 2}, with a delayed release. • Gas phase reducing regions above the bed would facilitate more prompt COS generation. - Abstract: Often perceived as a Cinderella material, there is growing appreciation for solid waste as a renewable content thermal process feed. Nonetheless, research on solid waste gasification and sulphur mechanisms in particular is lacking. This paper presents results from two related experiments on a novel two stage gasification process, at demonstration scale, using a sulphur-enriched wood pellet feed. Notable SO{sub 2} and relatively low COS levels (before gas cleaning) were interesting features of the trials, and not normally expected under reducing gasification conditions. Analysis suggests that localised oxygen rich regions within the fluid bed played a role in SO{sub 2}’s generation. The response of COS to sulphur in the feed was quite prompt, whereas SO{sub 2} was more delayed. It is proposed that the bed material sequestered sulphur from the feed, later aiding SO{sub 2} generation. The more reducing gas phase regions above the bed would have facilitated COS – hence its faster response. These results provide a useful insight, with further analysis on a suite of performed experiments underway, along with thermodynamic modelling.

  3. A particulate model of solid waste incineration in a fluidized bed combining combustion and heavy metal vaporization

    SciTech Connect

    Mazza, G.; Falcoz, Q.; Gauthier, D.; Flamant, G.

    2009-11-15

    This study aims to develop a particulate model combining solid waste particle combustion and heavy metal vaporization from burning particles during MSW incineration in a fluidized bed. The original approach for this model combines an asymptotic combustion model for the carbonaceous solid combustion and a shrinking core model to describe the heavy metal vaporization. A parametric study is presented. The global metal vaporization process is strongly influenced by temperature. Internal mass transfer controls the metal vaporization rate at low temperatures. At high temperatures, the chemical reactions associated with particle combustion control the metal vaporization rate. A comparison between the simulation results and experimental data obtained with a laboratory-scale fluid bed incinerator and Cd-spiked particles shows that the heavy metal vaporization is correctly predicted by the model. The predictions are better at higher temperatures because of the temperature gradient inside the particle. Future development of the model will take this into account. (author)

  4. Occurrence and persistence of fungicides in bed sediments and suspended solids from three targeted use areas in the United States

    USGS Publications Warehouse

    Smalling, Kelly L.; Reilly, Timothy J.; Sandstrom, Mark W.; Kuivila, Kathryn M.

    2013-01-01

    To document the environmental occurrence and persistence of fungicides, a robust and sensitive analytical method was used to measure 34 fungicides and an additional 57 current-use pesticides in bed sediments and suspended solids collected from areas of intense fungicide use within three geographic areas across the United States. Sampling sites were selected near or within agricultural research farms using prophylactic fungicides at rates and types typical of their geographic location. At least two fungicides were detected in 55% of the bed and 83% of the suspended solid samples and were detected in conjunction with herbicides and insecticides. Six fungicides were detected in all samples including pyraclostrobin (75%), boscalid (53%), chlorothalonil (41%) and zoxamide (22%). Pyraclostrobin, a strobilurin fungicide, used frequently in the United States on a variety of crops, was detected more frequently than p,p′-DDE, the primary degradate of p,p′-DDT, which is typically one of the most frequently occurring pesticides in sediments collected within highly agricultural areas. Maximum fungicide concentrations in bed sediments and suspended solids were 198 and 56.7 μg/kg dry weight, respectively. There is limited information on the occurrence, fate, and persistence of many fungicides in sediment and the environmental impacts are largely unknown. The results of this study indicate the importance of documenting the persistence of fungicides in the environment and the need for a better understanding of off-site transport mechanisms, particularly in areas where crops are grown that require frequent treatments to prevent fungal diseases.

  5. Coal slurry solids/coal fluidized bed combustion by-product mixtures as plant growth media

    USGS Publications Warehouse

    Darmody, R.G.; Green, W.P.; Dreher, G.B.

    1998-01-01

    Fine-textured, pyritic waste produced by coal cleaning is stored in slurry settling ponds that eventually require reclamation. Conventionally, reclamation involves covering the dewatered coal slurry solids (CSS) with 1.3 m of soil to allow plant growth and prevent acid generation by pyrite oxidation. This study was conducted to determine the feasiblity of a less costly reclamation approach that would eliminate the soil cover and allow direct seeding of plants into amended CSS materials. Potential acidity of the CSS would be neutralized by additions of fluidized-bed combustion by-product (FBCB), an alkaline by-product of coal combustion. The experiment involved two sources of CSS and FBCB materials from Illinois. Birdsfoot trefoil (Lotus corniculatus L.), tall fescue (Festuca arundinacea Schreb.), and sweet clover (Melilotus officinalis (L.) Lam.) were seeded in the greenhouse into pots containing mixtures of the materials. CSS-1 had a high CaCO3:FeS2 ratio and needed no FBCB added to compensate for its potential acidity. CSS-2 was mixed with the FBCB materials to neutralize potential acidity (labeled Mix A and B). Initial pH was 5.6, 8.8, and 9.2 for the CSS-1, Mix A, and Mix B materials, respectively. At the end of the 70-day experiment, pH was 5.9 for all mixtures. Tall fescue and sweet clover grew well in all the treatments, but birdsfoot trefoil had poor emergence and survival. Elevated tissue levels of B, Cd, and Se were found in some plants. Salinity, low moisture holding capacity, and potentially phytotoxic B may limit the efficacy of this reclamation method.

  6. Bacterial counts on teat skin and in new sand, recycled sand, and recycled manure solids used as bedding in freestalls.

    PubMed

    Rowbotham, R F; Ruegg, P L

    2016-08-01

    On modern dairy farms, environmental mastitis pathogens are usually the predominant cause of mastitis, and bedding often serves as a point of exposure to these organisms. The objective of this longitudinal study was to determine bacterial populations of 4 different bedding types [deep-bedded new sand (NES), deep-bedded recycled sand (RS), deep-bedded manure solids (DBMS), and shallow-bedded manure solids over foam core mattresses (SBMS)] and of teat skin swabs of primarily primiparous cows housed in a single facility over all 4 seasons. Samples of bedding were collected weekly (n=49wk) from pens that each contained 32 lactating dairy cows. Throughout the length of the same period, composite swabs of teat skin were collected weekly from all cows before and after premilking teat sanitation. Median numbers of streptococci and streptococci-like organisms (SSLO) were >8.6×10(6) cfu/g and >6.9×10(3) cfu/teat swab for all bedding types and teat swabs, respectively. Numbers of SSLO were greatest in samples of SBMS (2.1×10(8) cfu/g) and least in samples of NES (8.6×10(6) cfu/g), RS (1.3×10(7) cfu/g), and DBMS (1.7×10(7) cfu/g). Numbers of gram-negative bacteria in bedding (5.5×10(4) to 1.2×10(7) cfu/g) were fewer than numbers of SSLO (8.6×10(6) to 2.1×10(8) cfu/g). Numbers of coliform bacteria were greatest in samples of DBMS (2.2×10(6) cfu/g) and least in samples of NES (3.6×10(3) cfu/g). In general, the relative number of bacteria on teat skin corresponded to exposure in bedding. Numbers of gram-negative bacteria recovered from prepreparation teat swabs were greatest for cows bedded with DBMS (1.0×10(4) cfu/swab) and RS (2.5×10(3) cfu/swab) and least for cows bedded with NES (5.8×10(2) cfu/swab). Median numbers of coliform and Klebsiella spp. recovered from prepreparation teat swabs were below the limit of detection for all cows except those bedded with DBMS. Numbers of SSLO recovered from prepreparation teat swabs were least for cows bedded with DBMS (6.9

  7. MULTIFLUID EULERIAN MODELLING OF DENSE GAS-SOLID FLUIDIZED BED HYDRODYNAMICS: INFLUENCE OF THE DISSIPATION PARAMETERS

    SciTech Connect

    Reuge, N; Cadoret, L.; Pannala, Sreekanth; Syamlal, M; Coufort, C; Caussat, B

    2008-01-01

    Computational fluid dynamic (CFD) models must be thoroughly validated before they can be used with confidence for designing fluidized bed reactors. In this study, validation data were collected from a fluidized bed of (Geldart's group B) alumina particles operated at different gas velocities involving two fluidization hydrodynamic regimes (bubbling and slugging). The bed expansion, height of bed fluctuations, and frequency of fluctuations were measured from a videos of the fluidized bed. The Eulerian-Eulerian two fluid model MFIX was then used to simulate the experiments. Two different models for the particle stresses - Schaeffer (Syamlal et al., (1993), Schaeffer (1987)) and Princeton (Srivastava and Sundaresan (2003)) models - and different values of the restitution coefficient and internal angle of friction were evaluated. 3-D simulations are required for getting quantitative and qualitative agreement with experimental data. The results from the Princeton model are in better agreement with data than from the Schaeffer model. Both free-slip and Johnson-Jackson boundary conditions give nearly identical results. An increase in e from 0.8 to 1 leads to larger bed expansions and lower heights of fluctuations in the bubbling regime whereas it leads to unchanged bed expansion and to a massive reduction in the height of fluctuations in the slugging regime. The angle of internal friction (φ) in the range 10 -40 does not affect the bed expansion, but its reduction significantly reduces the height of fluctuations.

  8. Solid self-nanoemulsifying cyclosporin A pellets prepared by fluid-bed coating: preparation, characterization and in vitro redispersibility

    PubMed Central

    Lei, Yang; Lu, Yi; Qi, Jianping; Nie, Sufang; Hu, Fuqiang; Pan, Weisan; Wu, Wei

    2011-01-01

    Background: The objective of this study was to evaluate fluid-bed coating as a new technique to prepare a pellet-based solid self-nanoemulsifying drug delivery system (SNEDDS) using cyclosporin A as a model of a poorly water-soluble drug. Methods: The rationale of this technique was to entrap a Liquid SNEDDS in the matrix of the coating material, polyvinylpyrrolidone K30, by fluid-bed coating. Pseudoternary phase diagrams were used to screen the liquid SNEDDS formulations. The optimal formulation was composed of Labrafil M® 1944 CS, Transcutol P®, and Cremophor® EL in a ratio of 9:14:7. To prepare solid SNEDDS pellets, liquid SNEDDS was first dispersed in an aqueous solution of polyvinylpyrrolidone and then sprayed onto the surface of non-pareil pellets. Upon evaporation of water, polyvinylpyrrolidone precipitated and formed tight films to entrap the liquid SNEDDS. Visual observation and scanning electron microscopic analysis confirmed good appearance of the solid SNEDDS pellets. Results: Our results indicated that up to 40% of the liquid SNEDDS could be entrapped in the coating layer. Powder x-ray diffraction analysis confirmed nonexistence of crystalline cyclosporin A in the formulation. Solid SNEDDS pellets showed a slower redispersion rate than the liquid SNEDDS. An increase in the total liquid SNEDDS loading led to faster redispersion, whereas increased coating weight (up to 400%) significantly decreased the redispersion rate. Both cyclosporin A loading and protective coating with 5% polyvinylpyrrolidone K30 did not significantly affect the redispersion rate. Conclusion: It is concluded that fluid-bed coating is a new technique with considerable potential for preparation of pellet-based solid SNEDDS formulations. PMID:21589647

  9. Fluidized bed combustion of solid organic wastes and low-grade coals: Research and modeling

    SciTech Connect

    Borodulya, V.A.; Dikalenko, V.I.; Palchonok, G.I.; Stanchits, L.K.

    1995-12-31

    Experimental studies were carried out to investigate devolatilization and combustion of single spherical particles of wood, hydrolytic lignin from ethanol production, leather processing sewage sludge, and low-grade Belarusian brown coals in a fluidized bed of sand. A two-phase model of fluidized bed combustion of biowaste is proposed. The model takes into account combustion of both volatiles and char in the bed as well as in the freeboard. Experimentally obtained characteristics of devolatilization and char combustion are used as parameters of the model proposed.

  10. A Study of the Influence of Numerical Diffusion on Gas-Solid Flow Predictions in Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Ghandriz, Ronak; Sheikhi, Reza

    2015-11-01

    In this work, an investigation is made of the influence of numerical diffusion on the accuracy of gas-solid flow predictions in fluidized beds. This is an important issue particularly in bubbling fluidized beds since numerical error greatly affects the dynamics of bubbles and their associated mixing process. A bed of coal (classified as Geldart A) is considered which becomes fluidized as the velocity of nitrogen stream into the reactor is gradually increased. The fluidization process is simulated using various numerical schemes as well as grid resolutions. Simulations involve Eulerian-Eulerian two-phase flow modeling approach and results are compared with experimental data. It is shown that higher order schemes equipped with flux limiter give favorable prediction of bubble and particle dynamics and hence, the mixing process within the reactor. The excessive numerical diffusion associated with lower order schemes results in unrealistic prediction of bubble shapes and bed height. Comparison is also made of computational efficiency of various schemes. It is shown that the Monotonized Central scheme with down wind factor results in the shortest simulation time because of its efficient parallelization on distributed memory platforms.

  11. Investigation of a dual-particle liquid-solid circulating fluidized bed bioreactor for extractive fermentation of lactic acid.

    PubMed

    Patel, Manoj; Bassi, Amarjeet S; Zhu, Jesse J-X; Gomaa, Hassan

    2008-01-01

    A dual-particle liquid-solid circulating fluidized bed (DP-LSCFB) bioreactor has been constructed and investigated for the simultaneous production and extraction of lactic acid using immobilized Lactobacillus bulgaricus and ion-exchange resins. The apparatus consisted of a downer fluidized bed, 13 cm I.D. and 4.75 m tall, and a riser fluidized bed, 3.8 cm I.D. and 5.15 m in height. The lactic acid production and removal was carried out in the downer, while the riser was used for the recovery of lactic acid. A continuously recirculating bed of ion-exchange resin was used for adsorption of the produced acid as well as for maintaining optimum pH for bioconversion, thus eliminating the need for costly and complex chemical control approach used in conventional techniques. Studies using lactic acid aqueous solution as feed and sodium hydroxide solution as regeneration stream showed 93% lactic acid removal from the downer and 46% recovery in the riser under the conditions investigated. Such results prove the functionality of using the newly developed bioreactor design for the continuous production and recovery of products of biotechnological significance. PMID:19194893

  12. Fluid bed gasification--plasma converter process generating energy from solid waste: experimental assessment of sulphur species.

    PubMed

    Morrin, Shane; Lettieri, Paola; Chapman, Chris; Taylor, Richard

    2014-01-01

    Often perceived as a Cinderella material, there is growing appreciation for solid waste as a renewable content thermal process feed. Nonetheless, research on solid waste gasification and sulphur mechanisms in particular is lacking. This paper presents results from two related experiments on a novel two stage gasification process, at demonstration scale, using a sulphur-enriched wood pellet feed. Notable SO2 and relatively low COS levels (before gas cleaning) were interesting features of the trials, and not normally expected under reducing gasification conditions. Analysis suggests that localised oxygen rich regions within the fluid bed played a role in SO2's generation. The response of COS to sulphur in the feed was quite prompt, whereas SO2 was more delayed. It is proposed that the bed material sequestered sulphur from the feed, later aiding SO2 generation. The more reducing gas phase regions above the bed would have facilitated COS--hence its faster response. These results provide a useful insight, with further analysis on a suite of performed experiments underway, along with thermodynamic modelling. PMID:24176239

  13. Modeling and simulation of liquid-solid circulating fluidized bed ion exchange system for continuous protein recovery.

    PubMed

    Mazumder, Jahirul; Zhu, Jingxu; Bassi, Amarjeet S; Ray, Ajay K

    2009-09-01

    Liquid-solid circulating fluidized bed (LSCFB) is an integrated two-column (downcomer and riser) system which can accommodate two separate processes (adsorption and desorption) in the same unit with continuous circulation of the solid particles between the two columns. In this study, a mathematical model based on the assumption of homogeneous fluidization was developed considering hydrodynamics, adsorption-desorption kinetics and liquid-solid mass transfer. The simulation results showed good agreement with the available experimental results for continuous protein recovery. A parametric sensitivity study was performed to better understand the influence of different operating parameters on the BSA adsorption and desorption capacity of the system. The model developed can easily be extended to other applications of LSCFB. PMID:19466748

  14. Validation of a model for process development and scale-up of packed-bed solid-state bioreactors.

    PubMed

    Weber, Frans J; Oostra, Jaap; Tramper, Johannes; Rinzema, Arjen

    2002-02-15

    We have validated our previously described model for scale-up of packed-bed solid-state fermenters (Weber et al., 1999) with experiments in an adiabatic 15-dm(3) packed-bed reactor, using the fungi Coniothyrium minitans and Aspergillus oryzae. Effects of temperature on respiration, growth, and sporulation of the biocontrol fungus C. minitans on hemp impregnated with a liquid medium were determined in independent experiments, and the first two effects were translated into a kinetic model, which was incorporated in the material and energy balances of the packed-bed model. Predicted temperatures corresponded well with experimental results. As predicted, large amounts of water were lost due to evaporative cooling. With hemp as support no shrinkage was observed, and temperatures could be adequately controlled, both with C. minitans and A. oryzae. In experiments with grains, strong shrinkage of the grains was expected and observed. Nevertheless, cultivation of C. minitans on oats succeeded because this fungus did not form a tight hyphal network between the grains. However, cultivation of A. oryzae failed because shrinkage combined with the strong hyphal network formed by this fungus resulted in channeling, local overheating of the bed, and very inhomogeneous growth of the fungus. For cultivation of C. minitans on oats and for cultivation of A. oryzae on wheat and hemp, no kinetic models were available. Nevertheless, the enthalpy and water balances gave accurate temperature predictions when online measurements of oxygen consumption were used as input. The current model can be improved by incorporation of (1) gas-solids water and heat transfer kinetics to account for deviations from equilibrium observed with fast-growing fungi such as A. oryzae, and (2) the dynamic response of the fungus to changes in temperature, which were neglected in the isothermal kinetic experiments. PMID:11787011

  15. 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.

  16. Fine-grid simulations of gas-solids flow in a circulating fluidized bed

    SciTech Connect

    Benyahia, S.

    2012-01-01

    This research note demonstrates that more accurate predictions of a two-fluid model for the riser section of a circulating fluidized bed are obtained as the grid size is equally refined along all the directions of the gas-particle flow. However, two-fluid simulations of large-scale fluidized beds with such a fine mesh are currently computationally prohibitive. Alternatively,subgrid models can significantly reduce the simulation time of multiphase flow by using coarse mesh, whereas maintaining a high level of accuracy.

  17. Modeling of solid-side mass transfer in desiccant particle beds

    SciTech Connect

    Pesaran, A.A.; Mills, A.F.

    1984-02-01

    A model is proposed for heat and mass transfer in a packed bed of desiccant particles and accounts for both Knudsen and surface diffusion within the particles. Using the model, predictions are made for the response of thin beds of silica gel particles to a step change in air inlet conditions compared to mental results. The predictions are found to be satisfactory and, in general, superior to those of pseudogas-side controlled models commonly used for the design of desiccant dehumidifiers for solar air conditioning application.

  18. Lipase production by solid-state fermentation: cultivation conditions and operation of tray and packed-bed bioreactors.

    PubMed

    Gutarra, Melissa L E; Cavalcanti, Elisa D C; Castilho, Leda R; Freire, Denise M G; Sant'Anna, Geraldo L

    2005-01-01

    The production of lipase by Penicillium simplicissimum in solid-state fermentation was studied using babassu cake as the basal medium. Tray-type and packed-bed bioreactors were employed. In the former, the influence of temperature; content of the medium, and medium supplementation with olive oil, sugarcane molasses, corn steep liquor, and yeast hydrolysate was studied. For all combinations of supplements, a temperature of 30 degrees C, a moisture content of 70%, and a concentration of carbon source of 6.25% (m/m, dry basis) provided optimum conditions for lipase production. When used as single supplements olive oil and molasses also were able to provide high lipase activities (20 U/g). Using packed-bed bioreactors and molasses-supplemented medium, optimum conditions for enzyme production were air superficial velocities above 55 cm/min and temperatures below 28 degrees C. The lower temperature optimum found for these reactors is probably related to radial heat gradient formation inside the packed bed. Maximum lipase activities obtained in these bioreactors (26.4 U/g) were 30% higher than in tray-type reactors. PMID:15917592

  19. Influence of particle size on pyrolysis and gasification performance of municipal solid waste in a fixed bed reactor.

    PubMed

    Luo, Siyi; Xiao, Bo; Hu, Zhiquan; Liu, Shiming; Guan, Yanwen; Cai, Lei

    2010-08-01

    Pyrolysis and gasification of municipal solid waste (MSW) were carried out in a lab-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on product yield and composition. The bed temperature was varied from 600 to 900 degrees C and the MSW was separated into three different size fractions (below 5 mm, 50-10 mm and above 10 mm). Particle size and temperature had integrated effects on product yield and composition: higher temperature resulted in higher gas yield with less tar and char, and, at the same temperature, dry gas yield increased with a decrease in particle size, and char and tar yield decreased. The differences due to particle sizes in pyrolysis and gasification performance practically disappeared at the highest temperatures tested. Smaller particle sizes resulted in higher H(2) and CO contents for both pyrolysis and gasification of MSW. Minimizing the size of raw materials is an alternative method to improve the gas quality of MSW pyrolysis and gasification. PMID:20363619

  20. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed.

    PubMed

    Sun, Rui; Ismail, Tamer M; Ren, Xiaohan; Abd El-Salam, M

    2015-05-01

    In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k-ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW. PMID:25746177

  1. Evaluating of scale-up methodologies of gas-solid spouted beds for coating TRISO nuclear fuel particles using advanced measurement techniques

    NASA Astrophysics Data System (ADS)

    Ali, Neven Y.

    The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking (RPT) to measure in three-dimension (3D) solids velocity and their turbulent parameters. The measured local parameters and the analysis of the results obtained in this work validate our new methodology of scale up of gas-solid spouted beds by comparing for the similarity the phases' holdups and the dimensionless solids velocities and their turbulent parameters that are non-dimensionalized using the minimum spouting superficial gas velocity. However, the scale-up methodology of gas-solid spouted beds that is based on matching dimensionless groups has not been validated for hydrodynamics similarity with respect to the local parameters such as phases' holdups and dimensionless solids velocities and their turbulent parameters. Unfortunately, this method was validated in the literature by only measuring the global parameters. Thus, this work confirms that validation of the scale-up methods of gas-solid spouted beds for hydrodynamics similarity should reside on measuring and analyzing the local hydrodynamics parameters.

  2. Apparatus for controlling molten core debris

    DOEpatents

    Golden, Martin P. [Trafford, PA; Tilbrook, Roger W. [Monroeville, PA; Heylmun, Neal F. [Pittsburgh, PA

    1977-07-19

    Apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed.

  3. Apparatus for controlling molten core debris. [LMFBR

    DOEpatents

    Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

    1977-07-19

    Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures.

  4. Survival of coliform bacteria in static compost piles of dairy waste solids intended for freestall bedding.

    PubMed

    Mote, C R; Emerton, B L; Allison, J S; Dowlen, H H; Oliver, S P

    1988-06-01

    Dairy waste solids separated from a slurry by a centrifugal separator were composted in 12 static piles. Seven of the compost piles were naturally aerated, and five were aerated by a fan that forced air through the piles of solids. The natural aeration process aged the manure solids in an unconfined pile. The fan in the forced aeration process forced air into a perforated plenum beneath the compost piles. Dairy waste solids in each compost pile were heated into the thermophilic temperature range and generally composted well. At most sampling points, coliform bacteria declined to low or undetectable numbers early in the composting period. However, as the composting process proceeded, bacterial numbers increased to approximately those present in raw dairy waste solids. Findings of this study suggest that composting offers little benefit toward net reduction in coliform bacterial numbers in dairy waste solids. PMID:3403762

  5. Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass

    NASA Astrophysics Data System (ADS)

    Fotovat, Farzam

    This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions. A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (U<0.6 m/s), while at high velocities, the bubbling trend of beds containing different fractions of biomass is comparable. The addition of biomass particles to a bed of sand leads to an increase in the mean voidage of the bed; however, the voidage of each phase remains unaffected. It is observed that large biomass particles trigger a break-up of the bubbles, which results in boosting bubbling frequency. The fraction of bubbles at the center of the bed increases with the load of biomass. At the wall region, however, it starts to decrease by adding 2% wt. biomass to pure sand and then increases with the further addition of biomass. The Radioactive Particle Tracking (RPT) technique is implemented in the second section of this work to study the motion and distribution

  6. Investigation of gas–solids flow in a circulating fluidized bed using 3D electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Mao, Mingxu; Ye, Jiamin; Wang, Haigang; Yang, Wuqiang

    2016-09-01

    The hydrodynamics of gas–solids flow in the bottom of a circulating fluidized bed (CFB) are complicated. Three-dimensional (3D) electrical capacitance tomography (ECT) has been used to investigate the hydrodynamics in risers of different shapes. Four different ECT sensors with 12 electrodes each are designed according to the dimension of risers, including two circular ECT sensors, a square ECT sensor and a rectangular ECT sensor. The electrodes are evenly arranged in three planes to obtain capacitance in different heights and to reconstruct the 3D images by linear back projection (LBP) algorithm. Experiments were carried out on the four risers using sands as the solids material. The capacitance and differential pressure are measured under the gas superficial velocity from 0.6 m s‑1 to 3.0 m s‑1 with a step of 0.2 m s‑1. The flow regime is investigated according to the solids concentration and differential pressure. The dynamic property of bubbling flows is analyzed theoretically and the performance of the 3D ECT sensors is evaluated. The experimental results show that 3D ECT can be used in the CFB with different risers to predict the hydrodynamics of gas–solids bubbling flows.

  7. The Composition and Expansion Behavior of a Binary-Solid Fluidized Bed

    NASA Astrophysics Data System (ADS)

    Howley, Maureen A.; Glasser, Benjamin J.

    2000-11-01

    When a binary mixture of particles with different densities and sizes is fluidized, the particles will often segregate, forming monocomponent layers. However, this is only one possible outcome, and well-mixed states have been observed experimentally. This paper examines the hydrodynamics of such a mixture by generalizing equations of continuity and motion for a single component bed. Solutions are sought for a uniformly fluidized bed consisting of glass beads and carbon in water. Our results show that, under equilibrium conditions, the fluid-particle interactive force determines solution structure. We introduce a closure using an excluded volume approach. Computed solutions are shown to characterize the composition and expansion behavior of all possible mixing states, and provide an explanation of the layer inversion phenomenon. Comparison with experimental data suggests that the mechanism of bed expansion is not fully captured with an excluded volume assumption. Thus, we show how experimental data can be used to derive functional forms for the fluid-particle interactive force.

  8. Orbital Debris

    NASA Technical Reports Server (NTRS)

    Kessler, D. J. (Compiler); Su, S. Y. (Compiler)

    1985-01-01

    Earth orbital debris issues and recommended future activities are discussed. The workshop addressed the areas of environment definition, hazards to spacecraft, and space object management. It concluded that orbital debris is a potential problem for future space operations. However, before recommending any major efforts to control the environment, more data are required. The most significant required data are on the population of debris smaller than 4 cm in diameter. New damage criteria are also required. When these data are obtained, they can be combined with hypervelocity data to evaluate the hazards to future spacecraft. After these hazards are understood, then techniques to control the environment can be evaluated.

  9. A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.

    SciTech Connect

    Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.

    2013-03-01

    Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

  10. Measurement of Gas Velocities in the Presence of Solids in the Riser of a Cold Flow Circulating Fluidized Bed

    SciTech Connect

    Spenik, J.; Ludlow, J.C.; Compston, R.; Breault, R.W.

    2007-01-01

    The local gas velocity and the intensity of the gas turbulence in a gas/solid flow are a required measurement in validating the gas and solids flow structure predicted by computational fluid dynamic (CFD) models in fluid bed and transport reactors. The high concentration and velocities of solids, however, make the use of traditional gas velocity measurement devices such as pitot tubes, hot wire anemometers and other such devices difficult. A method of determining these velocities has been devised at the National Energy Technology Laboratory employing tracer gas. The technique developed measures the time average local axial velocity gas component of a gas/solid flow using an injected tracer gas which induces changes in the heat transfer characteristics of the gas mixture. A small amount of helium is injected upstream a known distance from a self-heated thermistor. The thermistor, protected from the solids by means of a filter, is exposed to gases that are continuously extracted from the flow. Changes in the convective heat transfer characteristics of the gas are indicated by voltage variations across a Wheatstone bridge. When pulsed injections of helium are introduced to the riser flow the change in convective heat transfer coefficient of the gas can be rapidly and accurately determined with this instrument. By knowing the separation distance between the helium injection point and the thermistor extraction location as well as the time delay between injection and detection, the gas velocity can easily be calculated. Variations in the measured gas velocities also allow the turbulence intensity of the gas to be estimated.

  11. Soy protein recovery in a solvent-free process using continuous liquid-solid circulating fluidized bed ion exchanger.

    PubMed

    Prince, Andrew; Bassi, Amarjeet S; Haas, Christine; Zhu, Jesse X; Dawe, Jennifer

    2012-01-01

    Soy protein concentrates and soy protein isolates act as ingredients in bakery, meat and dairy products, baby formulas, starting materials for spun textured vegetable products, and other nutritional supplements. In this study, the effectiveness of a liquid-solid circulating fluidized bed (LSCFB) ion exchanger is demonstrated for the recovery of soluble soy proteins from full fat and defatted soy flour. Under steady-state operating conditions, about 50% of the proteins could be recovered from the feed streams entering the ion exchanger. The LSCFB was shown to be a promising system for the recovery of soy protein from both defatted and full fat soy flour solutions. As the ion exchange process captures dissolved proteins, the system may offer a less damaging form of processing compared with the acid precipitation process where soy protein aggregates form and functionality is affected. In addition, the LSCFB allows simultaneous adsorption and desorption of the proteins allowing for a continuous operation. No prefiltration of feed containing suspended particles is required as well, because fluidization is used in place of packed bed technology to improve on current ion exchange processes. PMID:22002948

  12. Mathematical modeling of Kluyveromyces marxianus growth in solid-state fermentation using a packed-bed bioreactor.

    PubMed

    Mazutti, Marcio A; Zabot, Giovani; Boni, Gabriela; Skovronski, Aline; de Oliveira, Débora; Di Luccio, Marco; Rodrigues, Maria Isabel; Maugeri, Francisco; Treichel, Helen

    2010-04-01

    This work investigated the growth of Kluyveromyces marxianus NRRL Y-7571 in solid-state fermentation in a medium composed of sugarcane bagasse, molasses, corn steep liquor and soybean meal within a packed-bed bioreactor. Seven experimental runs were carried out to evaluate the effects of flow rate and inlet air temperature on the following microbial rates: cell mass production, total reducing sugar and oxygen consumption, carbon dioxide and ethanol production, metabolic heat and water generation. A mathematical model based on an artificial neural network was developed to predict the above-mentioned microbial rates as a function of the fermentation time, initial total reducing sugar concentration, inlet and outlet air temperatures. The results showed that the microbial rates were temperature dependent for the range 27-50 degrees C. The proposed model efficiently predicted the microbial rates, indicating that the neural network approach could be used to simulate the microbial growth in SSF. PMID:20035365

  13. Leaching behavior and possible resource recovery from air pollution control residues of fluidized bed combustion of municipal solid waste

    SciTech Connect

    Abbas, Z.; Andersson, B.A.; Steenari, B.M.

    1999-07-01

    Ash residues are generated at several points during combustion of municipal solid waste (MSW), i.e., in cyclones, electrostatic precipitators and fabric filters. Such residues are of a complex physical and chemical nature and are often enriched in soluble salts and heavy metals such as Pb, Cd and Zn. Fluidized bed combustion (FBC) of MSW is a relatively new technique and very little information is available about the leaching behavior of its residues. In this study, the total elemental composition, mineralogy and leaching behavior of cyclone and bag-house filter ashes from a bubbling fluidized bed (BFB) boiler fired with municipal solid waste have been investigated. In addition, the possibilities of recovery heavy metals from these ashes were studied. The long-term leaching behavior of the ash constituents was evaluated using a two-step batch leaching test known as the CEN-test, whereas short and medium term leaching behavior was evaluated using a Column test. The extraction of elements from cyclone and filter ashes with various acidic solutions was also investigated. The leaching behavior of acid washed ashes was evaluated using the CEN test. The cyclone ash was mainly composed of aluminosilicate minerals, whereas the filter ash consisted of chlorides and hydroxides of alkali and alkaline earth metals. The concentration of heavy metals such as Zn, Cu, Cd and Pb was higher in the filter ash than in the cyclone ash. The leached amounts of sulfates and Pb from the cyclone ash decreased with leaching test contact time, indicating the formation of secondary mineral phases. Large amounts of chlorides, sulfates, Ca, Cu and Pb were leached from the filter ash. Acid extraction removed large amounts ({gt}50%) of Zn, Pb and Cu from the filter ash and approximately 56% of the total amount of Zn present in the cyclone ash. An efficient removal of heavy metal species from these types of ashes can probably be achieved by application of a recycling or multi-step process.

  14. Comparison of coal/solid recovered fuel (SRF) with coal/refuse derived fuel (RDF) in a fluidised bed reactor

    SciTech Connect

    Wagland, S.T.; Kilgallon, P.; Coveney, R.; Garg, A.; Smith, R.; Longhurst, P.J.; Pollard, S.J.T.; Simms, N.

    2011-06-15

    An experimental study was undertaken to compare the differences between municipal solid waste (MSW) derived solid recovered fuel (SRF) (complying with CEN standards) and refuse derived fuel (RDF). Both fuels were co-combusted with coal in a 50 kW fluidised bed combustor and the metal emissions were compared. Synthetic SRF was prepared in the laboratory by grinding major constituents of MSW such as paper, plastic, textile and wood. RDF was obtained from a local mechanical treatment plant. Heavy metal emissions in flue gas and ash samples from the (coal + 10% SRF) fuel mixture were found to be within the acceptable range and were generally lower than that obtained for coal + 10% RDF fuel mixture. The relative distribution of heavy metals in ash components and the flue gas stream shows the presence of a large fraction (up to 98%) of most of the metals in the ash (except Hg and As). Thermo-gravimetric (TG) analysis of SRF constituents was performed to understand the behaviour of fuel mixtures in the absence and presence of air. The results obtained from the experimental study will enhance the confidence of fuel users towards using MSW-derived SRF as an alternative fuel.

  15. Comparison of coal/solid recovered fuel (SRF) with coal/refuse derived fuel (RDF) in a fluidized bed reactor.

    PubMed

    Wagland, S T; Kilgallon, P; Coveney, R; Garg, A; Smith, R; Longhurst, P J; Pollard, S J T; Simms, N

    2011-06-01

    An experimental study was undertaken to compare the differences between municipal solid waste (MSW) derived solid recovered fuel (SRF) (complying with CEN standards) and refuse derived fuel (RDF). Both fuels were co-combusted with coal in a 50 kW fluidized bed combustor and the metal emissions were compared. Synthetic SRF was prepared in the laboratory by grinding major constituents of MSW such as paper, plastic, textile and wood. RDF was obtained from a local mechanical treatment plant. Heavy metal emissions in flue gas and ash samples from the (coal+10% SRF) fuel mixture were found to be within the acceptable range and were generally lower than that obtained for coal+10% RDF fuel mixture. The relative distribution of heavy metals in ash components and the flue gas stream shows the presence of a large fraction (up to 98%) of most of the metals in the ash (except Hg and As). Thermo-gravimetric (TG) analysis of SRF constituents was performed to understand the behaviour of fuel mixtures in the absence and presence of air. The results obtained from the experimental study will enhance the confidence of fuel users towards using MSW-derived SRF as an alternative fuel. PMID:21288710

  16. Feasibility study on solidification of municipal solid waste incinerator fly ash with circulating fluidized bed combustion coal fly ash.

    PubMed

    Liu, Wenshi; Hou, Haobo; Zhang, Chuhao; Zhang, Dajie

    2009-05-01

    The objective of this study was to assess the feasibility of solidification of municipal solid waste incinerator (MSWI) fly ash with circulation fluidized bed combustion (CFBC) fly ash, which is unsuitable as a cement replacement due to its high amounts of carbon, lime and anhydrite. The solidification process was conducted on samples prepared from MSWI fly ash, binders (cement clinkers and CFBC fly ash were mixed at two replacement ratios) and water (water/solid weight ratio = 0.4), among which the MSWI fly ash replaced each binder at the ratio of 0, 20, 40, 60 and 80% by dry weight. The samples were subjected to compressive strength tests and Toxicity Characteristic Leaching Procedure and the results showed that all solidified MSWI fly ash can meet the landfill standard imposed by US EPA after 28 days of curing. Micro-analysis (X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrophotometry) revealed that the main hydrate products were C-S-H gel and ettringite, which have a positive effect on heavy metals retention. Therefore, this method provides a possibility to achieve a cheap and effective solution for MSWI fly ash management and use for CFBC fly ash. PMID:19423575

  17. Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

    SciTech Connect

    Sun, Rui; Ismail, Tamer M.; Ren, Xiaohan; Abd El-Salam, M.

    2015-05-15

    Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.

  18. Load maximization of a liquid-solid circulating fluidized bed bioreactor for nitrogen removal from synthetic municipal wastewater.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse

    2008-03-01

    A novel liquid-solid circulating fluidized bed bioreactor (LSCFB) configured with anoxic and aerobic columns and lava rock as the biofilm carrier was used to treat synthetic municipal wastewater. Four different empty bed contact times (EBCTs) of 0.82, 0.65, 0.55, and 0.44 h were examined to optimize nutrient removal capability of the system. The LSCFB demonstrated tertiary effluent quality organic and nitrogen removal efficiencies. Effluent characteristics of the LSCFB were soluble biological oxygen demand (SBOD)10 mg l(-1) and total nitrogen (TN)<10 mg l(-1) at organic loading rate (OLR) of 5.3 kg m(-3)d(-1) and nitrogen loading rate of 0.54 kg Nm(-3)d(-1). Remarkably low yields of 0.14, 0.17, 0.19, and 0.21 g VSS g(-1)COD were observed at OLR of 2.6, 3.2, 4.1 and 5.3 kg COD m(-3)d(-1), where increment of biomass growth and detachment rate were also experienced with increasing OLR. However the system demonstrated only 30% phosphorus removal, and mass balances along the anoxic and aerobic columns showed biological phosphorus removal in the system. Organic mass balance showed that approximately 40% of the influent COD was utilized in the anoxic column and the remaining COD was oxidized in the aerobic column. The system is very efficient in nitrification-denitrification, with more than 90% nitrification of ammonium and overall nitrogen removal in the LSCFB was 70+/-11% even at an EBCT of 0.44 h. PMID:18262217

  19. Application of noncatalytic gas-solid reactions for a single pellet of changing size to the modeling of fluidized-bed combustion of coal char containing sulfur

    SciTech Connect

    Rehmat, A.; Saxena, S.C.; Land, R.H.

    1980-09-01

    A mechanistic model is developed for coal char combustion, with sulfur retention by limestone or dolomite sorbent, in a gas fluidized bed employing noncatalytic single pellet gas-solid reactions. The shrinking core model is employed to describe the kinetics of chemical reactions taking place on a single pellet; changes in pellet size as the reaction proceeds are considered. The solids are assumed to be in back-mix condition whereas the gas flow is regarded to be in plug flow. Most char combustion occurs near the gas distributor plate (at the bottom of the bed), where the bubbles are small and consequently the mass transfer rate is high. For such a case, the analysis is considerably simplified by ignoring the bubble phase since it plays an insignificant role in the overall rate of carbon conversion. Bubble-free operation is also encounterd in the turbulent regime, where the gas flow is quite high and classical bubbles do not exist. Formulation of the model includes setting up heat and mass balance equations pertaining to a single particle (1) exposed to a varying reactant concentration along the height of the bed and (2) whose size changes during reaction. These equations are then solved numerically to account for particles of all sizes in the bed in obtaining the overall carbon conversion efficiency and resultant sulfur retention. In particular, the influence on sorbent requirement of several fluid-bed variables such as oxygen concentration profile, particle size, reaction rate for sulfation reaction, and suflur adsorption efficiency are examined.

  20. Determination of selected pharmaceutical residues in wastewater using an automated open bed solid phase microextraction system.

    PubMed

    Togunde, Oluranti P; Cudjoe, Erasmus; Oakes, Ken D; Mirnaghi, Fatemah S; Servos, Mark R; Pawliszyn, Janusz

    2012-11-01

    The detection of trace levels of pharmaceuticals in environmental matrices requires an analyte pre-concentration procedure to obtain the required sensitivity for quantitative determination. This research aims to develop a simple automated analytical method based on C(18) thin film solid phase microextraction (TF-SPME) for the simultaneous extraction of pharmaceutical compounds detected in surface waters. As a sample preparation method, solid phase microextraction, is a rapid, environmentally friendly, and a sensitive analytical technique which isolates and pre-concentrates trace organic pollutants from environmental water samples in a single step. High throughput analysis was achieved with the use of a robotic auto sampler which enabled parallel analyte extraction in a 96-well plate format. Application of the method was demonstrated using wastewater from pilot-scale municipal treatment plants and environmental water samples from wastewater-dominated reaches of the Grand River (adjacent Waterloo, ON) which were analysed using a liquid chromatography-mass spectrometry (LC-ESI-MS/MS) technique. The proposed method successfully determined concentrations of carbamazepine, fluoxetine, sertraline, and paroxetine in treated effluent at concentrations ranging from 240 to 3820 ng/L with a method detection limit of 2-13 ng/L with a relative standard deviation of less than 16%. Matrix effect was not observed with this method; therefore internal standards are not necessary for quantification of target compounds. The results suggest that this method is capable of detecting and quantifying many compounds present in both wastewater and wastewater-influenced surface water from multiple municipal sources. In this study, automated TF-SPME system is demonstrated as a simple and fast alternative method for high throughput analysis of pharmaceutical contaminants in environmental matrices. PMID:22999422

  1. Two stage fluid bed-plasma gasification process for solid waste valorisation: Technical review and preliminary thermodynamic modelling of sulphur emissions

    SciTech Connect

    Morrin, Shane; Lettieri, Paola; Chapman, Chris; Mazzei, Luca

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer We investigate sulphur during MSW gasification within a fluid bed-plasma process. Black-Right-Pointing-Pointer We review the literature on the feed, sulphur and process principles therein. Black-Right-Pointing-Pointer The need for research in this area was identified. Black-Right-Pointing-Pointer We perform thermodynamic modelling of the fluid bed stage. Black-Right-Pointing-Pointer Initial findings indicate the prominence of solid phase sulphur. - Abstract: Gasification of solid waste for energy has significant potential given an abundant feed supply and strong policy drivers. Nonetheless, significant ambiguities in the knowledge base are apparent. Consequently this study investigates sulphur mechanisms within a novel two stage fluid bed-plasma gasification process. This paper includes a detailed review of gasification and plasma fundamentals in relation to the specific process, along with insight on MSW based feedstock properties and sulphur pollutant therein. As a first step to understanding sulphur partitioning and speciation within the process, thermodynamic modelling of the fluid bed stage has been performed. Preliminary findings, supported by plant experience, indicate the prominence of solid phase sulphur species (as opposed to H{sub 2}S) - Na and K based species in particular. Work is underway to further investigate and validate this.

  2. Fate and transport of phenol in a packed bed reactor containing simulated solid waste.

    PubMed

    Saquing, Jovita M; Knappe, Detlef R U; Barlaz, Morton A

    2012-02-01

    An assessment of the risk to human health and the environment associated with the presence of organic contaminants (OCs) in landfills necessitates reliable predictive models. The overall objectives of this study were to (1) conduct column experiments to measure the fate and transport of an OC in a simulated solid waste mixture, (2) compare the results of column experiments to model predictions using HYDRUS-1D (version 4.13), a contaminant fate and transport model that can be parameterized to simulate the laboratory experimental system, and (3) determine model input parameters from independently conducted batch experiments. Experiments were conducted in which sorption only and sorption plus biodegradation influenced OC transport. HYDRUS-1D can reasonably simulate the fate and transport of phenol in an anaerobic and fully saturated waste column in which biodegradation and sorption are the prevailing fate processes. The agreement between model predictions and column data was imperfect (i.e., within a factor of two) for the sorption plus biodegradation test and the error almost certainly lies in the difficulty of measuring a biodegradation rate that is applicable to the column conditions. Nevertheless, a biodegradation rate estimate that is within a factor of two or even five may be adequate in the context of a landfill, given the extended retention time and the fact that leachate release will be controlled by the infiltration rate which can be minimized by engineering controls. PMID:22014583

  3. Fate and transport of phenol in a packed bed reactor containing simulated solid waste

    SciTech Connect

    Saquing, Jovita M.; Knappe, Detlef R.U.; Barlaz, Morton A.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Anaerobic column experiments were conducted at 37 Degree-Sign C using a simulated waste mixture. Black-Right-Pointing-Pointer Sorption and biodegradation model parameters were determined from batch tests. Black-Right-Pointing-Pointer HYDRUS simulated well the fate and transport of phenol in a fully saturated waste column. Black-Right-Pointing-Pointer The batch biodegradation rate and the rate obtained by inverse modeling differed by a factor of {approx}2. Black-Right-Pointing-Pointer Tracer tests showed the importance of hydrodynamic parameters to improve model estimates. - Abstract: An assessment of the risk to human health and the environment associated with the presence of organic contaminants (OCs) in landfills necessitates reliable predictive models. The overall objectives of this study were to (1) conduct column experiments to measure the fate and transport of an OC in a simulated solid waste mixture, (2) compare the results of column experiments to model predictions using HYDRUS-1D (version 4.13), a contaminant fate and transport model that can be parameterized to simulate the laboratory experimental system, and (3) determine model input parameters from independently conducted batch experiments. Experiments were conducted in which sorption only and sorption plus biodegradation influenced OC transport. HYDRUS-1D can reasonably simulate the fate and transport of phenol in an anaerobic and fully saturated waste column in which biodegradation and sorption are the prevailing fate processes. The agreement between model predictions and column data was imperfect (i.e., within a factor of two) for the sorption plus biodegradation test and the error almost certainly lies in the difficulty of measuring a biodegradation rate that is applicable to the column conditions. Nevertheless, a biodegradation rate estimate that is within a factor of two or even five may be adequate in the context of a landfill, given the extended retention

  4. Characterization of fly ash from a circulating fluidized bed incinerator of municipal solid waste.

    PubMed

    Zhang, Lin; Su, Xiaowen; Zhang, Zhixuan; Liu, Siming; Xiao, Yuxin; Sun, Mingming; Su, Jixin

    2014-11-01

    Treatment and disposal of fly ash in China are becoming increasingly difficult, since its production has steadily risen and its features are uncertain. The excess pollutant components of fly ash are the key factor affecting its treatment and resource utilization. In this study, fly ash samples collected from a power plant with circulating fluidized incinerators of municipal solid waste (MSW) located in Shandong Province (eastern China) were studied. The results showed that there were no obvious seasonal differences in properties of fly ash. The content of total salt, Zn, and pH exceeded the national standards and low-ring polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (Fs) were the main organic components of fly ash for this power plant, which posed great threats to the surrounding environment. The amount of Zn of fly ash was higher than other heavy metals, which should be due to alkaline batteries of MSW. The leachate of fly ash had low concentrations of heavy metals and the main soluble components were sulfates and chlorides. The major mineral crystals of fly ash were SiO2, CaSO4, and Fe2O3. The main organic pollutants were low-ring PAHs, polychlorinated PCDDs, and low-chlorinated PCDFs, and concentrations were lower than the limiting values of the national regulations. Additionally, the distribution of PCDD/Fs had either a positive or a negative linear correlation with fly ash and flue gas, which was associated with the chlorinated degree of PCDD/Fs. The analysis was conducted to fully understand the properties of fly ash and to take appropriate methods for further comprehensive utilization. PMID:24969433

  5. Conidia production by Beauveria bassiana (for the biocontrol of a diamondback moth) during solid-state fermentation in a packed-bed bioreactor.

    PubMed

    Kang, S W; Lee, S H; Yoon, C S; Kim, S W

    2005-01-01

    Conidia of Beauveria bassiana CS-1, which have the potential for the control of the diamondback moth (Plutella xylostella), were produced by solid-state fermentation (SSF) using a packed-bed bioreactor with rice straw and wheat bran. As the packing density and the bed height were increased, the production of conidia decreased. In a packed-bed bioreactor under no aeration and no addition of polypropylene (PP) foam (control), the total average of conidia was 4.9 x 10(8) g-1. The production of conidia was affected more by the addition of PP foam as an inert support than forced aeration and was approx. 23 times higher than that of the control. The total average of conidia produced by B. bassiana was 1.1-1.2 x 10(10) g-1 . PMID:15703878

  6. Models and correlations of the DEBRIS Late-Phase Melt Progression Model

    SciTech Connect

    Schmidt, R.C.; Gasser, R.D.

    1997-09-01

    The DEBRIS Late Phase Melt Progression Model is an assembly of models, embodied in a computer code, which is designed to treat late-phase melt progression in dry rubble (or debris) regions that can form as a consequence of a severe core uncover accident in a commercial light water nuclear reactor. The approach is fully two-dimensional, and incorporates a porous medium modeling framework together with conservation and constitutive relationships to simulate the time-dependent evolution of such regions as various physical processes act upon the materials. The objective of the code is to accurately model these processes so that the late-phase melt progression that would occur in different hypothetical severe nuclear reactor accidents can be better understood and characterized. In this report the models and correlations incorporated and used within the current version of DEBRIS are described. These include the global conservation equations solved, heat transfer and fission heating models, melting and refreezing models (including material interactions), liquid and solid relocation models, gas flow and pressure field models, and the temperature and compositionally dependent material properties employed. The specific models described here have been used in the experiment design analysis of the Phebus FPT-4 debris-bed fission-product release experiment. An earlier DEBRIS code version was used to analyze the MP-1 and MP-2 late-phase melt progression experiments conducted at Sandia National Laboratories for the US Nuclear Regulatory Commission.

  7. Propagated fixed-bed mixed-acid fermentation: effect of volatile solid loading rate and agitation at near-neutral pH.

    PubMed

    Golub, Kristina W; Golub, Stacey R; Meysing, Daniel M; Holtzapple, Mark T

    2012-11-01

    To increase conversion and product concentration, mixed-acid fermentation can use a countercurrent strategy where solids and liquids pass in opposite directions through a series of fermentors. To limit the requirement for moving solids, this study employed a propagated fixed-bed fermentation, where solids were stationary and only liquid was transferred. To evaluate the role of agitation, continuous mixing was compared with periodic mixing. The periodically mixed fermentation had similar conversion, but lower yield and selectivity. Increasing volatile solid loading rate from 1.5 to 5.1g non-acid volatile solids/(L(liq)·d) and increasing liquid retention time decreased yield, conversion, selectivity, but increased product concentrations. Compared to a previous study at high pH (~9), this study achieved higher performance at near neutral pH (~6.5) and optimal C-N ratios. Compared to countercurrent fermentation, propagated fixed-bed fermentations have similar selectivities and produce similar proportions of acetic acid, but have lower yields, conversion, productivities, and acid concentrations. PMID:22995159

  8. Dynamic Modeling and Control Studies of a Two-Stage Bubbling Fluidized Bed Adsorber-Reactor for Solid-Sorbent CO{sub 2} Capture

    SciTech Connect

    Modekurti, Srinivasarao; Bhattacharyya, Debangsu; Zitney, Stephen E.

    2013-07-31

    A one-dimensional, non-isothermal, pressure-driven dynamic model has been developed for a two-stage bubbling fluidized bed (BFB) adsorber-reactor for solid-sorbent carbon dioxide (CO{sub 2}) capture using Aspen Custom Modeler® (ACM). The BFB model for the flow of gas through a continuous phase of downward moving solids considers three regions: emulsion, bubble, and cloud-wake. Both the upper and lower reactor stages are of overflow-type configuration, i.e., the solids leave from the top of each stage. In addition, dynamic models have been developed for the downcomer that transfers solids between the stages and the exit hopper that removes solids from the bottom of the bed. The models of all auxiliary equipment such as valves and gas distributor have been integrated with the main model of the two-stage adsorber reactor. Using the developed dynamic model, the transient responses of various process variables such as CO{sub 2} capture rate and flue gas outlet temperatures have been studied by simulating typical disturbances such as change in the temperature, flowrate, and composition of the incoming flue gas from pulverized coal-fired power plants. In control studies, the performance of a proportional-integral-derivative (PID) controller, feedback-augmented feedforward controller, and linear model predictive controller (LMPC) are evaluated for maintaining the overall CO{sub 2} capture rate at a desired level in the face of typical disturbances.

  9. The physics of debris flows

    USGS Publications Warehouse

    Iverson, R.M.

    1997-01-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  10. Flow-injection determination of total organic fluorine with off-line defluorination reaction on a solid sorbent bed.

    PubMed

    Musijowski, Jacek; Trojanowicz, Marek; Szostek, Bogdan; da Costa Lima, José Luis Fontes; Lapa, Rui; Yamashita, Hiroki; Takayanagi, Toshio; Motomizu, Shoji

    2007-09-26

    Considering recent reports on widespread occurrence and concerns about perfluoroalkyl substances (PFAS) in environmental and biological systems, analysis of these compounds have gained much attention in recent years. Majority of analyte-specific methods are based on a LC/MS/MS or a GC/MS detection, however many environmental or biological studies would benefit from a total organic fluorine (TOF) determination. Presented work was aimed at developing a method for TOF determination. TOF is determined as an amount of inorganic fluoride obtained after defluorination reaction conducted off-line using sodium biphenyl reagent directly on the sorbent without elution of retained analytes. Recovered fluoride was analyzed using flow-injection system with either fluorimetric or potentiometric detection. The TOF method was tested using perfluorocarboxylic acids (PFCA), including perfluorooctanoic acid (PFOA), as model compounds. Considering low concentrations of PFAS in natural samples, solid-phase extraction as a preconcentration procedure was evaluated. Several carbon-based sorbents were tested, namely multi-wall carbon nanotubes, carbon nanofibres and activated carbon. Good sorption of all analytes was achieved and defluorination reaction was possible to carry out directly on a sorbent bed. Recoveries obtained for PFCAs, adsorbed on an activated carbon sorbent, and measured as TOF, were 99.5+/-1.7, 110+/-9.4, 95+/-26, 120+/-32, 110+/-12 for C4, C6, C8, C10 and C12-PFCA, respectively. Two flow systems that would enable the defluorination reaction and fluoride determination in a single system were designed and tested. PMID:17903477

  11. Refractive index matched suspensions as a tool for investigating entrainment by avalanches and debris flows

    NASA Astrophysics Data System (ADS)

    Bates, Belinda; Ancey, Christophe

    2015-04-01

    Geophysical gravity flows such as avalanches and debris flows are complicated mixtures of fluid and solids, often containing particle sizes of many orders of magnitude. In a debris flow, for example, the composition varies from head to tail, and from bottom to top due to particle size segregation and recirculation. In addition the solid components may have different masses and mechanical properties. For this reason, a complete understanding of substrate entrainment by this type of flow is still out of reach. A common strategy for advancing our understanding of the physics of processes like entrainment is to use a greatly simplified laboratory model of a debris flow, and take internal and bulk measurements. This idealized technique forms the basis of this study, in which a two-phase, monodisperse suspension of PMMA beads in a refractive-index matched suspending fluid flowed down a flume, encountering an entrainable region of the same suspension on the way. This study represents the first attempt of taking continuous internal velocity measurements inside a flowing, entraining model avalanche or debris flow in the laboratory. Interior PIV measurements of flow velocity were taken in the entrainable region, along with surface height measurements, to shed some light on the entrainment mechanisms and to see how the bulk flow responded. Further, some differential pressure measurements were made in the entrainable bed to see if pore-pressure peaks had any correlation with significant events during entrainment. We present our preliminary findings and discuss the suitability of the method to entrainment investigations.

  12. The debris-flow rheology myth

    USGS Publications Warehouse

    Iverson, R.M.

    2003-01-01

    Models that employ a fixed rheology cannot yield accurate interpretations or predictions of debris-flow motion, because the evolving behavior of debris flows is too complex to be represented by any rheological equation that uniquely relates stress and strain rate. Field observations and experimental data indicate that debris behavior can vary from nearly rigid to highly fluid as a consequence of temporal and spatial variations in pore-fluid pressure and mixture agitation. Moreover, behavior can vary if debris composition changes as a result of grain-size segregation and gain or loss of solid and fluid constituents in transit. An alternative to fixed-rheology models is provided by a Coulomb mixture theory model, which can represent variable interactions of solid and fluid constituents in heterogeneous debris-flow surges with high-friction, coarse-grained heads and low-friction, liquefied tails. ?? 2003 Millpress.

  13. The influence of process parameters in production of lipopeptide iturin A using aerated packed bed bioreactors in solid-state fermentation.

    PubMed

    Piedrahíta-Aguirre, C A; Bastos, R G; Carvalho, A L; Monte Alegre, R

    2014-08-01

    The strain Bacillus iso 1 co-produces the lipopeptide iturin A and biopolymer poly-γ-glutamic acid (γ-PGA) in solid-state fermentation of substrate consisting of soybean meal, wheat bran with rice husks as an inert support. The effects of pressure drop, oxygen consumption, medium permeability and temperature profile were studied in an aerated packed bed bioreactor to produce iturin A, diameter of which was 50 mm and bed height 300 mm. The highest concentrations of iturin A and γ-PGA were 5.58 and 3.58 g/kg-dry substrate, respectively, at 0.4 L/min after 96 h of fermentation. The low oxygen uptake rates, being 23.34 and 22.56 mg O2/kg-dry solid substrate for each air flow rate tested generated 5.75 W/kg-dry substrate that increased the fermentation temperature at 3.7 °C. The highest pressure drop was 561 Pa/m at 0.8 L/min in 24 h. This is the highest concentration of iturin A produced to date in an aerated packed bed bioreactor in solid-state fermentation. The results can be useful to design strategies to scale-up process of iturin A in aerated packed bed bioreactors. Low concentration of γ-PGA affected seriously pressure drop, decreasing the viability of the process due to generation of huge pressure gradients with volumetric air flow rates. Also, the low oxygenation favored the iturin A production due to the reduction of free void by γ-PGA production, and finally, the low oxygen consumption generated low metabolic heat. The results show that it must control the pressure gradients to scale-up the process of iturin A production. PMID:24504698

  14. Pilot-scale experience with biological nutrient removal and biomass yield reduction in a liquid-solid circulating fluidized bed bioreactor.

    PubMed

    Chowdhury, Nabin; Nakhla, George; Zhu, Jesse; Islam, Mohammad

    2010-01-01

    A pilot-scale liquid-solid circulating fluidized bed (LSCFB) bioreactor was developed at the Adelaide Pollution Control Plant, London, Ontario, Canada, to study its commercial viability for biological nutrient removal. Lava rock particles of 600 microm were used as a biomass carrier media. The LSCFB removed approximately 90% organic, 80% nitrogen, and 70% phosphorus at loading rates of 4.12 kg COD/m3 x d, 0.26 kg N/m3 x d, and 0.052 kg P/m3 x d, and an empty bed contact time of 1.5 hours. Effluent characterized by < 1.0 mg NH4-N/L, < 5.0 mg NO3-N/ L, < 1.0 mg PO4-P/L, < 10 mg TN/L, < 10 mg SBOD/L, and 10 to 15 mg volatile suspended solids (VSS)/L can easily meet the criteria for nonpotable reuse of treated wastewater. The system removed nutrients without using any chemicals, and the secondary clarifier removed suspended solids removal without chemicals. A significant reduction (approximately 75%) in biomass yield to 0.12 to 0.16 g VSS/g chemical oxygen demand (COD) was observed, primarily because of long biological solids retention time (SRT) of 20 to 39 days and a combination of anoxic and aerobic COD consumption. PMID:20942332

  15. Dioxins and their fingerprint in size-classified fly ash fractions from municipal solid waste incinerators in China--mechanical grate and fluidized bed units.

    PubMed

    Lu, Sheng-Yong; Du, Yingzhe; Yan, Jian-Hua; Li, Xiao-Dong; Ni, Ming-Jiang; Cen, Ke-Fa

    2012-06-01

    The distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), in brief dioxins, has seldom been addressed systematically in fly ash from municipal solid waste incinerators (MSWIs). This study shows the amount and fingerprint of PCDD/Fs in fly ash from four different Chinese MSWIs, that is, three mechanical grate units and one circulating fluidized bed unit. In these fly ash samples, dioxins-related parameters (international toxic equivalent quantity, total amount of PCDD/Fs, individual isomer classes, and 17 toxic 2,3,7,8-substituted congeners) all tend to increase with decreasing particle size for mechanical grate incinerators, yet only for the finest fraction for fluidized bed units. Moreover, the fluidized bed incinerator seems superior to grate incineration in controlling dioxins, yet a comparison is hampered by internal differences in the sample, for example, the fluidized bed fly ash has much lower carbon and chlorine contents. In addition, the presence of sulfur from mixing coal as supplemental fuel to the MSW may poison the catalytic steps in dioxins formation and thus suppress the formation of dioxins. With more residual carbon and chlorine in the fly ash, it is easier to form dioxins during cooling. Nevertheless, there is no apparent relation between Fe, Cu, and Zn contents and that of dioxins in fly ash. PMID:22788110

  16. Bed drain cover assembly for a fluidized bed

    DOEpatents

    Comparato, Joseph R.; Jacobs, Martin

    1982-01-01

    A loose fitting movable cover plate (36), suitable for the severe service encountered in a fluidized bed combustor (10), restricts the flow of solids into the combustor drain lines (30) during shutdown of the bed. This cover makes it possible to empty spent solids from the bed drain lines which would otherwise plug the piping between the drain and the downstream metering device. This enables use of multiple drain lines each with a separate metering device for the control of solids flow rate.

  17. Orbital debris-debris collision avoidance

    NASA Astrophysics Data System (ADS)

    Mason, James; Stupl, Jan; Marshall, William; Levit, Creon

    2011-11-01

    We focus on preventing collisions between debris and debris, for which there is no current, effective mitigation strategy. We investigate the feasibility of using a medium-powered (5 kW) ground-based laser combined with a ground-based telescope to prevent collisions between debris objects in low-Earth orbit (LEO). The scheme utilizes photon pressure alone as a means to perturb the orbit of a debris object. Applied over multiple engagements, this alters the debris orbit sufficiently to reduce the risk of an upcoming conjunction. We employ standard assumptions for atmospheric conditions and the resulting beam propagation. Using case studies designed to represent the properties (e.g. area and mass) of the current debris population, we show that one could significantly reduce the risk of nearly half of all catastrophic collisions involving debris using only one such laser/telescope facility. We speculate on whether this could mitigate the debris fragmentation rate such that it falls below the natural debris re-entry rate due to atmospheric drag, and thus whether continuous long-term operation could entirely mitigate the Kessler syndrome in LEO, without need for relatively expensive active debris removal.

  18. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  19. Method and apparatus for the separation of a gas-solids mixture in a circulating fluidized bed reactor

    SciTech Connect

    Vimalchand, Pannalal; Liu, Guohai; Peng, WanWang

    2010-08-10

    The system of the present invention includes a centripetal cyclone for separating particulate material from a particulate laden gas solids stream. The cyclone includes a housing defining a conduit extending between an upstream inlet and a downstream outlet. In operation, when a particulate laden gas-solids stream passes through the upstream housing inlet, the particulate laden gas-solids stream is directed through the conduit and at least a portion of the solids in the particulate laden gas-solids stream are subjected to a centripetal force within the conduit.

  20. Debris flows: behavior and hazard assessment

    USGS Publications Warehouse

    Iverson, Richard M.

    2014-01-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form lobate deposits when they spill onto valley floors. Because they have volumetric sediment concentrations that exceed 40 percent, maximum speeds that surpass 10 m/s, and sizes that can range up to ~109 m3, debris flows can denude slopes, bury floodplains, and devastate people and property. Computational models can accurately represent the physics of debris-flow initiation, motion and deposition by simulating evolution of flow mass and momentum while accounting for interactions of debris' solid and fluid constituents. The use of physically based models for hazard forecasting can be limited by imprecise knowledge of initial and boundary conditions and material properties, however. Therefore, empirical methods continue to play an important role in debris-flow hazard assessment.

  1. Solid-state Fermentation of Xylanase from Penicillium canescens 10-10c in a Multi-layer-packed Bed Reactor

    NASA Astrophysics Data System (ADS)

    Assamoi, Antoine A.; Destain, Jacqueline; Delvigne, Frank; Lognay, Georges; Thonart, Philippe

    Xylanase is produced by Penicillium canescens 10-10c from soya oil cake in static conditions using solid-state fermentation. The impact of several parameters such as the nature and the size of inoculum, bed-loading, and aeration is evaluated during the fermentation process. Mycelial inoculum gives more production than conidial inoculum. Increasing the quantity of inoculum enhances slightly xylanase production. Forced aeration induces more sporulation of strain and reduces xylanase production. However, forced moistened air improves the production compared to production obtained with forced dry air. In addition, increasing bed-loading reduces the specific xylanase production likely due to the incapacity of the Penicillium strain to grow deeply in the fermented soya oil cake mass. Thus, the best cultivation conditions involve mycelial inoculum form, a bed loading of 1-cm height and passive aeration. The maximum xylanase activity is obtained after 7 days of fermentation and attains 10,200 U/g of soya oil cake. These levels are higher than those presented in the literature and, therefore, show all the potentialities of this stock and this technique for the production of xylanase.

  2. Segregation dynamics in debris flows

    NASA Astrophysics Data System (ADS)

    Hill, K. M.; Fei, M.

    2014-12-01

    Debris flows are massive flows consisting of mixtures of particles of different sizes and interstitial fluids such as water and mud. In sheared mixtures of different-sized (same density) particles, it is well known that larger particles tend to go up (toward the free surface), and the smaller particles, down, commonly referred to as the "Brazil-nut problem" or "kinetic sieving". When kinetic sieving fluxes are combined with advection in flows, they can give rise to a spectacular range of segregation patterns. These segregation / advection dynamics are recognized as playing a role in the coarsening of a debris flow front (its "snout") and the coarsening of the self-formed channel sides or levees. Since particle size distribution influences the flow dynamics including entrainment of bed materials, modeling segregation dynamics in debris flows is important for modeling the debris flows themselves. In sparser systems, the Brazil-nut segregation is well-modeled using kinetic theory applied to dissipative systems, where an underlying assumption involves random, uncorrelated collisions. In denser systems, where kinetic theory breaks down we have recently developed a new mixture model that demonstrates the segregation fluxes are driven by two effects associated with the kinetic stress or granular temperature (the kinetic energy associated with velocity fluctuations): (1) the difference between the partitioning of kinetic and contact stresses among the species in the mixture and (2) a kinetic stress gradient. Both model frameworks involve the temperature gradient as a driving force for segregation, but kinetic theory sends larger particles toward lower temperatures, and our mixture model sends larger particles away from lower temperatures. Which framework works under what conditions appears to depend on correlations in the flow such as those manifested in clusters and force chains. We discuss the application of each theoretical framework to representing segregation dynamics

  3. Debris Flow Monitoring in the Acquabona Watershed on the Dolomites (Italian Alps)

    NASA Astrophysics Data System (ADS)

    Berti, M.; Genevois, R.; LaHusen, R.; Simoni, A.; Tecca, P. R.

    2000-09-01

    In 1997 a field monitoring system was installed in Acquabona Creek in the Dolomites (Eastern Italian Alps) to observe the hydrologic conditions for debris flow occurrence and some dynamic properties of debris flow. The monitoring system consists of three remote stations: an upper one located at the head of a deeply-incised channel and two others located downstream. The system is equipped with sensors for measuring rainfall, pore pressures in the mobile channel bottom, ground vibrations, debris flow depth, total normal stress and fluid pore-pressure at the base of the flow. Two video cameras record events at the upper channel station and one video is installed at the lowermost station. During summer 1998, three debris flows (volumes from less than 1000 m3 up to 9000 m3) occurred at Acquabona. The following results were obtained from a preliminary analysis of the data: 1) All of the flows were triggered by rainfalls of less than 1 hour duration, with peak rainfall intensities ranging from 4.8 to 14.7 mm / 10 minute. 2) Debris flows initiated in several reaches of the channel, including the head of the talus slope. 3) The initial surges of the mature flows had a higher solid concentration and a lower velocity (up to 4 m/s) than succeeding, more dilute surges (more than 7 m/s). 4) Total normal stress and pore fluid pressures measured at the base of the flow. (mean depth about 1.1 m) were similar (about 15 kPa), indicating a completely liquefied flow. 5) Peak flows entrained debris at a rate of about 6 m 3/m of channel length and channel bed scouring was proportional to the local slope gradient and was still evident in the lower channel where the slope was 7°.

  4. Debris flow monitoring in the Acquabona watershed on the Dolomites (Italian Alps)

    USGS Publications Warehouse

    Berti, M.; Genevois, R.; LaHusen, R.; Simoni, A.; Tecca, P.R.

    2000-01-01

    In 1997 a field monitoring system was installed in Acquabona Creek in the Dolomites (Eastern Italian Alps) to observe the hydrologic conditions for debris flow occurrence and some dynamic properties of debris flow. The monitoring system consists of three remote stations: an upper one located at the head of a deeply-incised channel and two others located downstream. The system is equipped with sensors for measuring rainfall, pore pressures in the mobile channel bottom, ground vibrations, debris flow depth, total normal stress and fluid pore-pressure at the base of the flow. Two video cameras record events at the upper channel station and one video is installed at the lowermost station. During summer 1998, three debris flows (volumes from less than 1000 m3 up to 9000 m3) occurred at Acquabona. The following results were obtained from a preliminary analysis of the data: 1) All of the flows were triggered by rainfalls of less than 1 hour duration, with peak rainfall intensities ranging from 4.8 to 14.7 mm / 10 minute. 2) Debris flows initiated in several reaches of the channel, including the head of the talus slope. 3) The initial surges of the mature flows had a higher solid concentration and a lower velocity (up to 4 m/s) than succeeding, more dilute surges (more than 7 m/s). 4) Total normal stress and pore fluid pressures measured at the base of the flow (mean depth about 1.1 m) were similar (about 15 kPa), indicating a completely liquefied flow. 5) Peak flows entrained debris at a rate of about 6 m3/m of channel length and channel bed scouring was proportional to the local slope gradient and was still evident in the lower channel where the slope was 7??. ?? 2000 Elsevier Science Ltd. All rights reserved.

  5. Coupled Eulerian-Lagrangian transport of large debris by tsunamis

    NASA Astrophysics Data System (ADS)

    Conde, Daniel A. S.; Ferreira, Rui M. L.; Sousa Oliveira, Carlos

    2016-04-01

    Tsunamis are notorious for the large disruption they can cause on coastal environments, not only due to the imparted momentum of the incoming wave but also due to its capacity to transport large quantities of solid debris, either from natural or human-made sources, over great distances. A 2DH numerical model under development at CERIS-IST (Ferreira et al., 2009; Conde, 2013) - STAV2D - capable of simulating solid transport in both Eulerian and Lagrangian paradigms will be used to assess the relevance of Lagrangian-Eulerian coupling when modelling the transport of solid debris by tsunamis. The model has been previously validated and applied to tsunami scenarios (Conde, 2013), being well-suited for overland tsunami propagation and capable of handling morphodynamic changes in estuaries and seashores. The discretization scheme is an explicit Finite Volume technique employing flux-vector splitting and a reviewed Roe-Riemann solver. Source term formulations are employed in a semi-implicit way, including the two-way coupling of the Lagrangian and Eulerian solvers by means of conservative mass and momentum transfers between fluid and solid phases. The model was applied to Sines Port, a major commercial port in Portugal, where two tsunamigenic scenarios are considered: an 8.5 Mw scenario, consistent with the Great Lisbon Earthquake and Tsunami of the 1st November 1755 (Baptista, 2009), and an hypothetical 9.5 Mw worst-case scenario based on the same historical event. Open-ocean propagation of these scenarios were simulated with GeoClaw model from ClawPack (Leveque, 2011). Following previous efforts on the modelling of debris transport by tsunamis in seaports (Conde, 2015), this work discusses the sensitivity of the obtained results with respect to the phenomenological detail of the employed Eulerian-Lagrangian formulation and the resolution of the mesh used in the Eulerian solver. The results have shown that the fluid to debris mass ratio is the key parameter regarding the

  6. Orbital Debris: A Chronology

    NASA Technical Reports Server (NTRS)

    Portree, Davis S. F. (Editor); Loftus, Joseph P., Jr. (Editor)

    1999-01-01

    This chronology covers the 37-year history of orbital debris concerns. It tracks orbital debris hazard creation, research, observation, experimentation, management, mitigation, protection, and policy. Included are debris-producing, events; U.N. orbital debris treaties, Space Shuttle and space station orbital debris issues; ASAT tests; milestones in theory and modeling; uncontrolled reentries; detection system development; shielding development; geosynchronous debris issues, including reboost policies: returned surfaces studies, seminar papers reports, conferences, and studies; the increasing effect of space activities on astronomy; and growing international awareness of the near-Earth environment.

  7. Experimental study of head loss and filtration for LOCA debris

    SciTech Connect

    Rao, D.V.; Souto, F.J.

    1996-02-01

    A series of controlled experiments were conducted to obtain head loss and filtration characteristics of debris beds formed of NUKON{trademark} fibrous fragments, and obtain data to validate the semi-theoretical head loss model developed in NUREG/CR-6224. A thermally insulated closed-loop test set-up was used to conduct experiments using beds formed of fibers only and fibers intermixed with particulate debris. A total of three particulate mixes were used to simulate the particulate debris. The head loss data were obtained for theoretical fiber bed thicknesses of 0.125 inches to 4.0 inches; approach velocities of 0.15 to 1.5 ft/s; temperatures of 75 F and 125 F; and sludge-to-fiber nominal concentration ratios of 0 to 60. Concentration measurements obtained during the first flushing cycle were used to estimate the filtration efficiencies of the debris beds. For test conditions where the beds are fairly uniform, the head loss data were predictable within an acceptable accuracy range by the semi-theoretical model. The model was equally applicable for both pure fiber beds and the mixed beds. Typically the model over-predicted the head losses for very thin beds and for thin beds at high sludge-to-fiber mass ratios. This is attributable to the non-uniformity of such debris beds. In this range the correlation can be interpreted to provide upper bound estimates of head loss. This is pertinent for loss of coolant accidents in boiling water reactors.

  8. Low temperature SO{sub 2} removal with solid sorbents in a circulating fluidized bed absorber. Final report

    SciTech Connect

    Lee, S.K.; Keener, T.C.

    1994-10-10

    A novel flue gas desulfurization technology has been developed at the University of Cincinnati incorporating a circulating fluidized bed absorber (CFBA) reactor with dry sorbent. The main features of CFBA are high sorbent/gas mixing ratios, excellent heat and mass transfer characteristics, and the ability to recycle partially utilized sorbent. Subsequently, higher SO{sub 2} removal efficiencies with higher overall sorbent utilization can be realized compared with other dry sorbent injection scrubber systems.

  9. Report on orbital debris

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The success of space endeavors depends upon a space environment sufficiently free of debris to enable the safe and dependable operation of spacecraft. An environment overly cluttered with debris would threaten the ability to utilize space for a wide variety of scientific, technological, military, and commercial purposes. Man made space debris (orbital debris) differs from natural meteoroids because it remains in earth orbit during its lifetime and is not transient through the space around the Earth. The orbital debris environment is considered. The space environment is described along with sources of orbital debris. The current national space policy is examined, along with ways to minimize debris generation and ways to survive the debris environment. International efforts, legal issues and commercial regulations are also examined.

  10. Debris exhaust system

    DOEpatents

    McBride, D.D.; Bua, D.; Domankevitz, Y.; Nishioka, N.

    1998-06-23

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping. 9 figs.

  11. Debris exhaust system

    DOEpatents

    McBride, Donald D.; Bua, Dominic; Domankevitz, Yacov; Nishioka, Norman

    1998-01-01

    A debris removal system removes debris from a work site by flowing fluid away from the work site toward the periphery of a structure. The fluid flow can be kept constant around the periphery so that debris is removed evenly. The structure can have a reduced cross section between the fluid inlet and the work site so that the resulting increased fluid velocity works to prevent debris from escaping.

  12. Orbital Debris and NASA's Measurement Program

    NASA Astrophysics Data System (ADS)

    Africano, J. L.; Stansbery, E. G.

    2002-05-01

    Since the launch of Sputnik in 1957, the number of manmade objects in orbit around the Earth has dramatically increased. The United States Space Surveillance Network (SSN) tracks and maintains orbits on over nine thousand objects down to a limiting diameter of about ten centimeters. Unfortunately, active spacecraft are only a small percentage ( ~ 7%) of this population. The rest of the population is orbital debris or ``space junk" consisting of expended rocket bodies, dead payloads, bits and pieces from satellite launches, and fragments from satellite breakups. The number of these smaller orbital debris objects increases rapidly with decreasing size. It is estimated that there are at least 130,000 orbital debris objects between one and ten centimeters in diameter. Most objects smaller than 10 centimeters go untracked! As the orbital debris population grows, the risk to other orbiting objects, most importantly manned space vehicles, of a collision with a piece of debris also grows. The kinetic energy of a solid 1 cm aluminum sphere traveling at an orbital velocity of 10 km/sec is equivalent to a 400 lb. safe traveling at 60 mph. Fortunately, the volume of space in which the orbiting population resides is large, collisions are infrequent, but they do occur. The Space Shuttle often returns to earth with its windshield pocked with small pits or craters caused by collisions with very small, sub-millimeter-size pieces of debris (paint flakes, particles from solid rocket exhaust, etc.), and micrometeoroids. To get a more complete picture of the orbital-debris environment, NASA has been using both radar and optical techniques to monitor the orbital debris environment. This paper gives an overview of the orbital debris environment and NASA's measurement program.

  13. Debris flow initiation in proglacial gullies on Mount Rainier, Washington

    NASA Astrophysics Data System (ADS)

    Legg, Nicholas T.; Meigs, Andrew J.; Grant, Gordon E.; Kennard, Paul

    2014-12-01

    Effects of climate change, retreating glaciers, and changing storm patterns on debris flow hazards concern managers in the Cascade Range (USA) and mountainous areas worldwide. During an intense rainstorm in November 2006, seven debris flows initiated from proglacial gullies of separate basins on the flanks of Mount Rainier. Gully heads at glacier termini and widespread failure of gully walls imply that overland flow was transformed into debris flow along gullies. We characterized gully change and morphology, and assessed spatial distributions of debris flows to infer the processes and conditions for debris flow initiation. Slopes at gully heads were greater than ~ 0.35 m m- 1 (19°) and exhibited a significant negative relationship with drainage area. A break in slope-drainage area trends among debris flow gullies also occurs at ~ 0.35 m m- 1, representing a possible transition to fluvial sediment transport and erosion. An interpreted hybrid model of debris flow initiation involves bed failure near gully heads followed by sediment recruitment from gully walls along gully lengths. Estimates of sediment volume loss from gully walls demonstrate the importance of sediment inputs along gullies for increasing debris flow volumes. Basin comparisons revealed significantly steeper drainage networks and higher elevations in debris flow-producing than non-debris flow-producing proglacial areas. The high slopes and elevations of debris flow-producing proglacial areas reflect positive slope-elevation trends for the Mount Rainier volcano. Glacier extent therefore controls the slope distribution in proglacial areas, and thus potential for debris flow generation. As a result, debris flow activity may increase as glacier termini retreat onto slopes inclined at angles above debris flow initiation thresholds.

  14. Dimensional analysis of natural debris flows

    NASA Astrophysics Data System (ADS)

    Zhou, Gordon; Ouyang, Chaojun

    2015-04-01

    Debris flows occur when masses of poorly sorted sediment, agitated and saturated with water, surge down slopes in response to gravitational attraction. They are of great concern because they often cause catastrophic disasters due to the long run-out distance and large impact forc-es. Different from rock avalanches and sediment-laden water floods, both solid and fluid phases affected by multiple parameters can influence the motion of debris flows and govern their rheological properties. A dimensional analysis for a systematic study of the governing parameters is presented in this manuscript. Multiple dimensionless numbers with clear physical meanings are critically reviewed. Field data on natural debris flows are available here based on the fifty years' observation and measurement in the Jiangjia Gully, which is located in the Dongchuan City, Yunnan Province of China. The applications of field data with the dimensional analysis for studying natural debris flows are demonstrated. Specific values of dimensionless numbers (e.g., modified Savage Number, Reynolds number, Friction number) for classifying flowing regimes of natural debris flows on the large scales are obtained. Compared to previous physical model tests conducted mostly on small scales, this study shows that the contact friction between particles dominates in natural debris flows. In addition, the solid inertial stress due to particle collisions and the pore fluid viscous shear stress play key roles in governing the dynamic properties of debris flows and the total normal stress acting on the slope surfaces. The channel width as a confinement to the flows can affect the solids discharge per unit width significantly. Furthermore, a dimensionless number related to pore fluid pressure dissipation is found for distinguishing surge flows and continuous flows in field satisfactorily. It indicates that for surge debris flows, the high pore fluid pressures generated in granular body dissipate quite slowly and may

  15. Effects of the Basal Boundary on Debris-flow Dynamics

    NASA Astrophysics Data System (ADS)

    Iverson, R. M.; Logan, M.; Lahusen, R. G.; Berti, M.

    2006-12-01

    Data aggregated from 37 large-scale experiments reveal some counterintuitive effects of bed roughness on debris-flow dynamics. In each experiment 10 m3 of water-saturated sand and gravel, mixed with 1 to 12% silt and clay by dry weight, was abruptly released from a gate at the head of a 2-m wide, 1.2-m deep, 82.5-m long rectangular flume inclined 31° throughout most of its length and adjoined to a gently sloping, planar runout surface at its toe. The flume's basal boundary consisted of either a smooth, planar concrete surface or a concrete surface roughened with a grid of conical bumps. Tilt-table tests with dry debris-flow sediment showed that this roughness imparted a basal friction angle of 38°, comparable to the sediment's internal friction angle of 38-42°, whereas the smooth-bed friction angle was 28°. About 20 electronic sensors installed in the flume yielded data on flow speeds and depths as well as basal stresses and pore pressures. Behavior observed in all experiments included development of steep, unsaturated, coarse-grained debris-flow snouts and tapering, liquefied, fine-grained tails. Flows on the rough bed were typically about 50% thicker and 20% slower than flows on the smooth bed, although the rough bed caused snout steepening that enabled flow fronts to move faster than expected, given the increased bed friction. Moreover, flows on rough beds ran out further than flows on smooth beds owing to enhanced grain-size segregation and lateral levee formation. With the rough bed, measured basal stresses and pore pressures differed little from values expected from static gravitational loading of partially liquefied debris. With the smooth bed, however, measured basal stresses and pore pressures were nearly twice as large as expected values. This anomaly resulted from flow disturbance at the upstream lips of steel plates in which sensors were mounted. The lips produced barely visible ripples in otherwise smooth flow surfaces, yet sufficed to generate

  16. SCFA lead lab technical assistance at Oak Ridge Y-12 nationalsecurity complex: Evaluation of treatment and characterizationalternatives of mixed waste soil and debris at disposal area remedialaction DARA solids storage facility (SSF)

    SciTech Connect

    Hazen, Terry

    2002-08-26

    On July 17-18, 2002, a technical assistance team from the U.S. Department of Energy (DOE) Subsurface Contaminants Focus Area (SCFA) met with the Bechtel Jacobs Company Disposal Area Remedial Action (DARA) environmental project leader to review treatment and characterization options for the baseline for the DARA Solids Storage Facility (SSF). The technical assistance request sought suggestions from SCFA's team of technical experts with experience and expertise in soil treatment and characterization to identify and evaluate (1) alternative treatment technologies for DARA soils and debris, and (2) options for analysis of organic constituents in soil with matrix interference. Based on the recommendations, the site may also require assistance in identifying and evaluating appropriate commercial vendors.

  17. Multiobjective optimization of the operation of a liquid-solid circulating fluidized bed ion-exchange system for continuous protein recovery.

    PubMed

    Mazumder, Jahirul; Zhu, Jingxu; Bassi, Amarjeet S; Ray, Ajay K

    2009-08-01

    Like most real-life processes, the operation of liquid-solid circulating fluidized bed (LSCFB) system for continuous protein recovery is associated with several objectives such as maximization of production rate and recovery of protein, and minimization of amount solid ion-exchange resin requirement, all of which need to be optimized simultaneously. In this article, multiobjective optimization of a LSCFB system for continuous protein recovery was carried out using an experimentally validated mathematical model to find the scope for further improvements in its operation. Elitist non-dominated sorting genetic algorithm with its jumping gene adaptation was used to solve a number of bi- and tri-objective function optimization problems. The optimization resulted in Pareto-optimal solution, which provides a broad range of non-dominated solutions due to conflicting behavior of the operating parameters on the system performance indicators. Significant improvements were achieved, for example, the production rate at optimal operation increased by 33%, using 11% less solid compared to reported experimental results for the same recovery level. The effects of operating variables on the optimal solutions are discussed in detail. The multiobjective optimization study reported here can be easily extended for the improvement of LSCFB system for other applications. PMID:19378264

  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. Microbial population in the biomass adhering to supporting material in a packed-bed reactor degrading organic solid waste.

    PubMed

    Sasaki, Kengo; Haruta, Shin; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

    2007-06-01

    An anaerobic packed-bed reactor using carbon fiber textiles (CFT) as the supporting material was continuously operated using an artificial garbage slurry. 16S rRNA gene analysis showed that many bacteria in the biomass adhering to CFT were closely related to those observed from other anaerobic environments, although a wide variety of unidentified bacteria were also found. Dot blot hybridization results clarified that 16S rRNA levels of methanogens in the adhering biomass were higher than those in the effluent. Based on microscopic observation, the adhering biomass consisted of microorganisms, organic material, and void areas. Bacteria and Archaea detected by fluorescence in situ hybridization were distributed from the surface to the inner regions of the adhering biomass. Methanosarcina sp. tended to be more abundant in the inner part of the adhering biomass than at the surface. This is the first report to elucidate the structure of the microbial community on CFT in a packed-bed reactor. PMID:17334757

  1. Removal of sulfur dioxide from a continuously operated binary fluidized bed reactor using inert solids and hydrated lime.

    PubMed

    Pisani, R; de Moraes, D

    2004-06-18

    Sulfur dioxide pollutant was treated in the laboratory with hydrated lime particles having a mean diameter of 9.1 microm in a continuously operating binary fluidized bed reactor also containing inert sand particles with sizes varying from 500 to 590 microm. The influence of temperature (500, 600, 700 and 800 degrees C) on the reaction medium, of the superficial velocity of the gas (0.8, 1.0 and 1.2 m/s), and of the Ca/S molar ratio (1, 2 and 3) on the SO2 removal efficiency were investigated for an inflow gas concentration of 1000 ppm and an initially static bed height of 10.0 cm. The pollutant removal efficiency proved to depend on the temperature and the velocity of the gaseous flow and was strongly influenced by the Ca/S molar ratio. The maximum efficiency of 97.7% was achieved at a temperature of 700 degrees C, a Ca/S ratio of 3 and a velocity of 0.8 m/s. The lime particles' mean residence time was determined by an indirect method, which consisted of integrating the gas concentration curves normalized with respect to time. Based on a calculation of the critical transition velocities, it was concluded that the reactor operated in a bubbling regime under each condition investigated here. PMID:15177758

  2. Magnetic resonance measurements of high-velocity particle motion in a three-dimensional gas-solid spouted bed

    NASA Astrophysics Data System (ADS)

    Müller, C. R.; Holland, D. J.; Sederman, A. J.; Dennis, J. S.; Gladden, L. F.

    2010-11-01

    Magnetic resonance imaging has been used to measure particle velocities, exceeding 1ms-1 in a two-phase granular system, namely, a spouted bed. The measurements are complicated due to the high voidage, i.e., low particle density, in the region of the highest particle velocity. However, applying gradient shapes which allow fast switching and, thus, short encoding and observation times in combination with a short echo time enable these measurements. It was found that the profile of the particle velocity is nonparabolic. Based on these measurements it was possible to confirm observations made in numerical simulations that there must be a continuous momentum exchange between the annulus region and the spout along the entire length of the spout.

  3. Magnetic resonance measurements of high-velocity particle motion in a three-dimensional gas-solid spouted bed.

    PubMed

    Müller, C R; Holland, D J; Sederman, A J; Dennis, J S; Gladden, L F

    2010-11-01

    Magnetic resonance imaging has been used to measure particle velocities, exceeding 1 m s⁻¹ in a two-phase granular system, namely, a spouted bed. The measurements are complicated due to the high voidage, i.e., low particle density, in the region of the highest particle velocity. However, applying gradient shapes which allow fast switching and, thus, short encoding and observation times in combination with a short echo time enable these measurements. It was found that the profile of the particle velocity is nonparabolic. Based on these measurements it was possible to confirm observations made in numerical simulations that there must be a continuous momentum exchange between the annulus region and the spout along the entire length of the spout. PMID:21230423

  4. An Assessment of Potential Detectors to Monitor the Man-made Orbital Debris Environment. [space debris

    NASA Technical Reports Server (NTRS)

    Reynolds, R. C.; Ruck, G. T.

    1983-01-01

    Observations using NORAD radar showed that man made debris exceeds the natural environment for large objects. For short times (a few days to a few weeks) after solid rocket motor (SRM) firings in LEO, man made debris in the microparticle size range also appears to exceed the meteoroid environment. The properties of the debris population between these size regimes is currently unknown as there has been no detector system able to perform the required observations. The alternatives for obtaining data on this currently unobserved segment of the population are assessed.

  5. Finial Scientific/Technical Report: Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuel

    SciTech Connect

    Dr. Wei-Ping Pan; Dr. John T. Riley

    2005-10-10

    Chemical Looping Combustion is a novel combustion technology for the inherent separation of the greenhouse gas, CO{sub 2}. In 1983, Richter and Knoche proposed reversible combustion, which utilized both the oxidation and reduction of metal. Metal associated with its oxidized form as an oxygen carrier was circulated between two reactors--oxidizer and reducer. In the reducer, the solid oxygen carrier reacts with the fuel to produce CO{sub 2}, H{sub 2}O and elemental metal only. Pure CO{sub 2} will be obtained in the exit gas stream from the reducer after H{sub 2}O is condensed. The pure CO{sub 2} is ready for subsequent sequestration. In the oxidizer, the elemental metal reacts with air to form metal oxide and separate oxygen from nitrogen. Only nitrogen and some unused oxygen are emitted from the oxidizer. The advantage of CLC compared to normal combustion is that CO{sub 2} is not diluted with nitrogen but obtained in a relatively pure form without any energy needed for separation. In addition to the energy-free purification of CO{sub 2}, the CLC process also provides two other benefits. First, NO{sub x} formation can be largely eliminated. Secondly, the thermal efficiency of a CLC system is very high. Presently, the CLC process has only been used with natural gas. An oxygen carrier based on an energy balance analysis and thermodynamics analysis was selected. Copper (Cu) seems to be the best choice for the CLC system for solid fuels. From this project, the mechanisms of CuO reduction by solid fuels may be as follows: (1) If pyrolysis products of solid fuels are available, reduction of CuO could start at about 400 C or less. (2) If pyrolysis products of solid fuels are unavailable and the reduction temperature is lower, reduction of CuO could occur at an onset temperature of about 500 C, char gasification reactivity in CO{sub 2} was lower at lower temperatures. (3) If pyrolysis products of solid fuels are unavailable and the reduction temperature is higher than 750 C

  6. Anaerobic digestion of horse dung mixed with different bedding materials in an upflow solid-state (UASS) reactor at mesophilic conditions.

    PubMed

    Böske, Janina; Wirth, Benjamin; Garlipp, Felix; Mumme, Jan; Van den Weghe, Herman

    2014-04-01

    Aim of this study was to investigate the use of upflow anaerobic solid-state (UASS) digestion for treating horse manure. Biochemical methane potential (BMP) tests conducted for varying mixtures of dung (hay and silage feed) and bedding material (wheat straw, flax, hemp, wood chips) showed that straw mixed with hay horse dung has the highest potential of [Formula: see text] . Continuous mesophilic digestion was conducted for 238 days using a single-stage UASS reactor (27 L) and a two-stage UASS system with an anaerobic filter (AF, 21 L). Increasing the organic loading rate (OLR) from 2.5 to 4.5 g vs L(-1)d(-1) enhanced the methane rate of the single-stage reactor from 0.262 to 0.391 LL(-1)d(-1) while the methane yield declined from 104.8 to 86.9 L kg vs(-1). The two-stage system showed similar yields. Thus, for solid-state digestion of horse manure a single-stage UASS reactor appears sufficient. PMID:24583222

  7. Floor Space Needs for Laboratory Mice: C56BL/6 Males in Solid-bottom Cages with Bedding.

    PubMed

    Fullwood, Steven; Hicks, Tiffanie A.; Brown, Jack C.; Norman, Reid L.; McGlone, John J.

    1998-12-01

    Measures of performance, mortality, adrenal weights, plasma glucocorticoid concentration, and selected immune measures were collected in an attempt to define space needs of laboratory mice. Six replications of 3 C57BL/6 male mice per cage were examined while housed on bedding at 5, 10, 15, or 20 in(2) (32.2, 64.5, 96.8, or 129 cm(2)) per mouse. Body weights were not influenced by treatment; however, mice in smaller spaces (5 in(2) per mouse) consumed or wasted more feed and water than mice given greater space allowances. Mice given the least amount of space (5 in(2) per mouse) had greater lymphocyte proliferation in response to the T-cell mitogen PHA than mice given more space. Mice provided 10 in(2) per mouse had greater natural killer cytotoxicity than mice given greater or less space. Mouse mortality was greater as more space was provided. In contrast, adrenal weights and plasma glucocorticoid concentrations were progressively greater with lower space allowances. The National Research Council 1996 recommendation of 15 in(2) per mouse, for this strain and sex of mice, would result in greater mortality and reduced activity of some immune measures. Socially housed male C57BL/6 mice will benefit from less space than recommended by the National Research Council in 1996. PMID:11406686

  8. Space debris detection and mitigation

    SciTech Connect

    Allahdadi, F.

    1993-01-01

    Space debris is defined as all useless man-made objects in space. This conference covers the following areas: debris detection, tracking, and surveillance; orbital debris analytical modeling; debris environment and safety issues; and orbital debris mitigation. Separate abstracts were prepared for 26 papers in this conference.

  9. Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed

    SciTech Connect

    Pacciani, R.; Muller, C.R.; Davidson, J.F.; Dennis, J.S.; Hayhurst, A.N.

    2009-08-05

    The extent and mechanism of sulfation and carbonation of limestone, dolomite, and chalk, were compared with a novel, synthetic sorbent (85 wt % CaO and 15 wt % Ca{sub 12}A{sub l14}O{sub 33}), by means of experiments undertaken in a small, electrically heated fluidized bed. The sorbent particles were used either (I) untreated, sieved to two particle sizes and reacted with two different concentrations of SO{sub 2}, or (ii) after being cycled 20 times between carbonation, in 15 vol % CO{sub 2} in N2, and calcination, in pure N2, at 750 degrees C. The uptake of untreated limestone and dolomite was generally low (<0.2 g(SO{sub 2})/g(sorbent)), confirming previous results, However, the untreated chalk and the synthetic sorbent were found to be substantially more reactive with SO{sub 2}, and their final uptake was significantly higher (>0.5 g(SO{sub 2})/g(sorbent)) and essentially independent of the particle size. Here, comparisons are made on the basis of the sorbents in the calcined state. The capacities for the uptake of SO{sub 2}, on a basis of unit mass of calcined sorbent, were comparable for the chalk and the synthetic sorbent. However, previous work has demonstrated the ability of the synthetic sorbent to retain its capacity for CO{sub 2} over many cycles of carbonation and calcination: much more so than natural sorbents such as chalk and limestone. Accordingly, the advantage of the synthetic sorbent is that it could be used to remove CO{sub 2} from flue gases and, at the end of its life, to remove SO{sub 2} on a once-through basis.

  10. EMERGING TECHNOLOGY BULLETIN: SPOUTED BED REACTOR

    EPA Science Inventory

    The Spouted Bed Reactor (SBR) technology utilizes the unique attributes of the "spouting " fluidization regime, which can provide heat transfer rates comparable to traditional fluid beds, while providing robust circulation of highly heterogeneous solids, concurrent with very agg...

  11. SCDAP/RELAP5 Modeling of Movement of Melted Material through Porous Debris in Lower Head (Rev. 2)

    SciTech Connect

    Siefken, Larry James

    1999-10-01

    A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material my permeate in about 120 s to the bottom of a 1 m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material at the bottom of the debris bed decreases the thermal resistance of the interface between the debris bed and the lower head. This report is a revision of the report with the identifier of INEEL/EXT-98-01178 REV 1, entitled "SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head."

  12. Debris-flow deposition: Effects of pore-fluid pressure and friction concentrated at flow margins

    USGS Publications Warehouse

    Major, J.J.; Iverson, R.M.

    1999-01-01

    Measurements of pore-fluid pressure and total bed-normal stress at the base of several ???10 m3 experimental debris flows provide new insight into the process of debris-flow deposition. Pore-fluid pressures nearly sufficient to cause liquefaction were developed and maintained during flow mobilization and acceleration, persisted in debris-flow interiors during flow deceleration and deposition, and dissipated significantly only during postdepositional sediment consolidation. In contrast, leading edges of debris flows exhibited little or no positive pore-fluid pressure. Deposition therefore resulted from grain-contact friction and bed friction concentrated at flow margins. This finding contradicts models that invoke widespread decay of excess pore-fluid pressure, uniform viscoplastic yield strength, or pervasive grain-collision stresses to explain debris-flow deposition. Furthermore, the finding demonstrates that deposit thickness cannot be used to infer the strength of flowing debris.

  13. Orbital Debris Mitigation

    NASA Technical Reports Server (NTRS)

    Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

    2014-01-01

    Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

  14. Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on a mixed bed adsorbent (acid activated montmorillonite-silica gel) column.

    PubMed

    Rajesh, N; Mishra, Braja Gopal; Pareek, Pawan Kumar

    2008-02-01

    A novel approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on a mixture of acid activated montmorillonite (AAM)-silica gel column. The effect of various parameters such as acidity, stability of the column, sample volume, interfering ions, etc., were studied in detail. The adsorbed complex could be easily eluted using polyethylene glycol-sulfuric acid mixture and the concentration of chromium has been determined using visible spectrophotometry. The calibration graph was linear in the range 0-1microgmL(-1) chromium(VI) with a detection limit of 6microgL(-1). A highest preconcentration factor of 25 could be obtained for 250mL sample volume using glass wool as support for the mixed bed adsorbent. Chromium(VI) could be effectively separated from other ions such as nickel, copper, zinc, chloride, sulfate, nitrate, etc., and the method has been successfully applied to study the recovery of chromium in electroplating waste water and spiked water samples. PMID:17604681

  15. Low temperature SO{sub 2} removal with solid sorbents in a circulating fluidized bed absorber. Quarterly report, May 1--July 31, 1992

    SciTech Connect

    Lee, S.K.; Keener, T.C.

    1992-08-12

    The nozzle installed in the circulating fluidized bed absorber (CFBA) was slightly modified because of a technical difficulty in making the small holes less than 100 {mu}m. The holes were punctured with a very tiny drill bits in diameter of 275 {mu}m, and the number of holes were adjusted. The 951 TGA (Du Pont Co.) was also modified for the kinetic information on the hydration and sulfation of limes under low temperatures. The modified thermalgravimetric analyzer (TGA) includes a syringe in order to simulate the water sprayings in a CFBA. Water droplets through the needle attached to the syringe are added onto the lime sample in a TGA. Two discrete ranges of Dravo limes were prepared as solid sorbents for sulfation tests. One ranged between 1095 {mu}m (16 mesh) and 2380 {mu}m (8 mesh) in diameter and the other ranged between 595 {mu}m (30 mesh) and 1095 {mu}m (16 mesh). The experimental methods for kinetic studies with TGA and for CFBA operation were established through the pre-operation of CFBA.

  16. Solid phase extraction of chromium(VI) from aqueous solutions by adsorption of its diphenylcarbazide complex on a mixed bed adsorbent (acid activated montmorillonite-silica gel) column

    NASA Astrophysics Data System (ADS)

    Rajesh, N.; Mishra, Braja Gopal; Pareek, Pawan Kumar

    2008-02-01

    A novel approach has been developed for the solid phase extraction of chromium(VI) based on the adsorption of its diphenylcarbazide complex on a mixture of acid activated montmorillonite (AAM)-silica gel column. The effect of various parameters such as acidity, stability of the column, sample volume, interfering ions, etc., were studied in detail. The adsorbed complex could be easily eluted using polyethylene glycol-sulfuric acid mixture and the concentration of chromium has been determined using visible spectrophotometry. The calibration graph was linear in the range 0-1 μg mL -1 chromium(VI) with a detection limit of 6 μg L -1. A highest preconcentration factor of 25 could be obtained for 250 mL sample volume using glass wool as support for the mixed bed adsorbent. Chromium(VI) could be effectively separated from other ions such as nickel, copper, zinc, chloride, sulfate, nitrate, etc., and the method has been successfully applied to study the recovery of chromium in electroplating waste water and spiked water samples.

  17. 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

  18. Woody debris flow behavior from experimental analysis

    NASA Astrophysics Data System (ADS)

    Bateman, Allen; Medina, Vicente; Morloti, Emanuele; Renaud, Alexis

    2010-05-01

    A consequence of debris flow in streams are well known, the collapse of the stream flooding all over the land. The high momentum flux of those flows can devastate houses, drag and crushes cars, etc. The presence of woody debris into the flow rise the flow depth and increment the collapse of the streams, bridges and structures. The present preliminary study offer a qualitative comparison between a debris flow and a woody debris flow with similar flow characteristics. To obtain this a series of experiments were performed in the Morph-dynamic Laboratory of the Hydraulic, Marine and Environmental Department. A high slope flume of 9 meters length, 40 cm width and 60 cm high was used. Up to 5 experiments were running in the flume. Initially the material was placed dry in the bed conforming a 20 cm depth of granular material changing the way of water wave entrance. Always water wave was introduced as a step function with different step size and different flow duration in order to introduce the same volume of water, just enough to saturate all the material in the channel. The flow was filmed with a handycam in order to see the general flow characteristics and with a high speed camera, just in a section, to visualize the flow velocities. Several woody pieces were placed along the channel to simulate the presence of wood and tress in the stream. Each tree was constructed in such a way that each one have a root made by rocks simulating a real root and different mass distribution. The comparison with experiments without wood was clever to understand the influence of woods in the debris flow. The woody debris flow alone creates natural dams along the stream without presence of inciters obstacles along the reach.

  19. Field Observations of Basal Forces and Fluid Pore Pressure in a Debris Flow

    NASA Astrophysics Data System (ADS)

    McArdell, B. W.; Bartelt, P.; Kowalski, J.

    2006-12-01

    The interaction of the soil material and interstitial fluid is central to understanding the dynamics of debris flows, however it has been rarely investigated for natural debris flows. Using results from a large force plate (4 m wide, 2 m long) installed on the bed of the Illgraben torrent channel, Switzerland, we describe measurements of normal, shear, and fluid pore pressure for a naturally-released debris flow with a front speed of 1.4 ms-1 that traveled more than 2 km along a gently-sloping (8 to 10%) channel. Peak values of all parameters were observed near the relatively dry granular flow front (flow depth= 1.05 m, normal stress= 23 kPa, shear stress= 2.8 kPa, basal fluid pore pressure= 15 kPa) and decreased approximately in-phase with the flow depth over the remainder of the flow. Assuming that the depths of the fluid and solid phases are identical after 20 s, as indicated by video recordings, and that a static description of the pressure distribution within the fluid phase is approximately valid, the ratio of effective stress to shear stress yields plausible estimates of the Coulomb basal friction angle near the front of the flow. Large non-lithostatic pressures are not apparent in our data; calculated bulk densities of the flow remaining at about 2200 kgm-3 over the most of the flow. The bulk density of the fluid phase calculated from the measured fluid pore pressure and flow height, assuming a hydrostatic pore pressure distribution, is 1200---1300 kgm-3. An alternative explanation is that the fluid pressure contains both hydrostatic and dynamics components. To explore this idea, we assume that a dynamic pore pressure component is proportional to the strength of the shearing of the solid phase or to the strength of the collisions of the particles comprising the solid phase, which we approximate using data from a geophone installed on the force plate. We find only a weak correlation between the geophone signal and a dynamic pore pressure component for this

  20. Tsunami Generated by a Two-Phase Submarine Debris Flow

    NASA Astrophysics Data System (ADS)

    Pudasaini, S. P.

    2012-04-01

    The general two-phase debris flow model proposed by Pudasaini (2011) is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model includes several essential physical aspects, including Mohr-Coulomb plasticity for the solid stress, while the fluid stress is modelled as a solid volume fraction gradient enhanced non-Newtonian viscous stress. The generalized interfacial momentum transfer includes the viscous drag, buoyancy, and the virtual mass. The generalized drag covers both the solid-like and fluid-like contributions, and can be applied to linear to quadratic drags. Strong couplings exist between the solid and the fluid momentum transfer. The advantage of the real two-phase debris flow model over classical single-phase or quasi-two-phase models is that by considering the solid (and/or the fluid) volume fraction appropriately, the initial mass can be divided into several (even mutually disjoint) parts; a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This offers a unique and innovative opportunity within a single framework to simultaneously simulate (a) the sliding debris (or landslide), (b) the water lake or ocean, (c) the debris impact at the lake or ocean, (d) tsunami generation and propagation, (e) mixing and separation between the solid and the fluid phases, and (f) sediment transport and deposition process in the bathymetric surface. The new model is applied to two-phase subaerial and submarine debris flows. Benchmark numerical simulations reveal that the dynamics of the debris impact induced tsunamis are fundamentally different than the tsunami generated by pure rock avalanche and landslides. Special attention is paid to study the basic features of the debris impact to the mountain lakes or oceans. This includes the generation, amplification and propagation of the multiple

  1. SPECS: Orbital debris removal

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The debris problem has reached a stage at which the risk to satellites and spacecraft has become substantial in low Earth orbit (LEO). This research discovered that small particles posed little threat to spacecraft because shielding can effectively prevent these particles from damaging the spacecraft. The research also showed that, even though collision with a large piece of debris could destroy the spacecraft, the large pieces of debris pose little danger because they can be tracked and the spacecraft can be maneuvered away from these pieces. Additionally, there are many current designs to capture and remove large debris particles from the space environment. From this analysis, it was decided to concentrate on the removal of medium-sized orbital debris, that is, those pieces ranging from 1 cm to 50 cm in size. The current design incorporates a transfer vehicle and a netting vehicle to capture the medium-sized debris. The system is based near an operational space station located at 28.5 deg inclination and 400 km altitude. The system uses ground-based tracking to determine the location of a satellite breakup or debris cloud. These data are uploaded to the transfer vehicle, which proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the

  2. EFFECT EVALUATION OF DEBRIS FLOW COUNTERMEASURES WITH KANAKO (CASE STUDY ON HONGQIAO GULLY, CHINA)

    NASA Astrophysics Data System (ADS)

    Nakatani, Kana; Liu, Jinfeng; Satofuka, Yoshifumi; Mizuyama, Takahisa

    Debris flow is a natural disaster common in mountainous areas in Japan and China. It has great destructive force because of its high density and speed, and often causes great losses to human life and the economy. Therefore, countermeasures such as sabo facilities are very essential to reduce the damages. In this study, we applied GUI equipped debris flow simulator KANAKO to evaluate the effects of the debris flow countermeasures in Hongqiao Gully, Sichuan Province, China. The results show that the full dams which were constructed in 2001 still have the function for controlling debris flow to a certain degree. Because the trapped debris flow materials decrease the gully bed slope, and debris flow velocity decreases consequently. Through the comprehensive control of debris flow including trapping, drainage and deposition works, the simulation results indicate that the effects of the countermeasures in 2001 and 2006 are very good. The countermeasures can ensure residents’ life and property on the alluvial fan.

  3. Debris entrainment and landform genesis during tidewater glacier surges

    NASA Astrophysics Data System (ADS)

    Lovell, Harold; Fleming, Edward J.; Benn, Douglas I.; Hubbard, Bryn; Lukas, Sven; Rea, Brice R.; Noormets, Riko; Flink, Anne E.

    2015-08-01

    The englacial entrainment of basal debris during surges presents an opportunity to investigate processes acting at the glacier bed. The subsequent melt-out of debris-rich englacial structures during the quiescent phase produces geometrical ridge networks on glacier forelands that are diagnostic of surge activity. We investigate the link between debris entrainment and proglacial geomorphology by analyzing basal ice, englacial structures, and ridge networks exposed at the margins of Tunabreen, a tidewater surge-type glacier in Svalbard. The basal ice facies display clear evidence for brittle and ductile tectonic deformation, resulting in overall thickening of the basal ice sequence. The formation of debris-poor dispersed facies ice is the result of strain-induced metamorphism of meteoric ice near the bed. Debris-rich englacial structures display a variety of characteristics and morphologies and are interpreted to represent the incorporation and elevation of subglacial till via the squeezing of till into basal crevasses and hydrofracture exploitation of thrust faults, reoriented crevasse squeezes, and preexisting fractures. These structures are observed to melt-out and form embryonic geometrical ridge networks at the base of a terrestrially grounded ice cliff. Ridge networks are also located at the terrestrial margins of Tunabreen, neighboring Von Postbreen, and in a submarine position within Tempelfjorden. Analysis of network characteristics allows these ridges to be linked to different formational mechanisms of their parent debris-rich englacial structures. This in turn provides an insight into variations in the dominant tectonic stress regimes acting across the glacier during surges.

  4. Density Estimations in Laboratory Debris Flow Experiments

    NASA Astrophysics Data System (ADS)

    Queiroz de Oliveira, Gustavo; Kulisch, Helmut; Malcherek, Andreas; Fischer, Jan-Thomas; Pudasaini, Shiva P.

    2016-04-01

    Bulk density and its variation is an important physical quantity to estimate the solid-liquid fractions in two-phase debris flows. Here we present mass and flow depth measurements for experiments performed in a large-scale laboratory set up. Once the mixture is released and it moves down the inclined channel, measurements allow us to determine the bulk density evolution throughout the debris flow. Flow depths are determined by ultrasonic pulse reflection, and the mass is measured with a total normal force sensor. The data were obtained at 50 Hz. The initial two phase material was composed of 350 kg debris with water content of 40%. A very fine pebble with mean particle diameter of 3 mm, particle density of 2760 kg/m³ and bulk density of 1400 kg/m³ in dry condition was chosen as the solid material. Measurements reveal that the debris bulk density remains high from the head to the middle of the debris body whereas it drops substantially at the tail. This indicates lower water content at the tail, compared to the head and the middle portion of the debris body. This means that the solid and fluid fractions are varying strongly in a non-linear manner along the flow path, and from the head to the tail of the debris mass. Importantly, this spatial-temporal density variation plays a crucial role in determining the impact forces associated with the dynamics of the flow. Our setup allows for investigating different two phase material compositions, including large fluid fractions, with high resolutions. The considered experimental set up may enable us to transfer the observed phenomena to natural large-scale events. Furthermore, the measurement data allows evaluating results of numerical two-phase mass flow simulations. These experiments are parts of the project avaflow.org that intends to develop a GIS-based open source computational tool to describe wide spectrum of rapid geophysical mass flows, including avalanches and real two-phase debris flows down complex natural

  5. Orbital debris: A technical assessment

    NASA Technical Reports Server (NTRS)

    Gleghorn, George; Asay, James; Atkinson, Dale; Flury, Walter; Johnson, Nicholas; Kessler, Donald; Knowles, Stephen; Rex, Dietrich; Toda, Susumu; Veniaminov, Stanislav

    1995-01-01

    To acquire an unbiased technical assessment of (1) the research needed to better understand the debris environment, (2) the necessity and means of protecting spacecraft against the debris environment, and (3) potential methods of reducing the future debris hazard, NASA asked the National Research Council to form an international committee to examine the orbital debris issue. The committee was asked to draw upon available data and analyses to: characterize the current debris environment, project how this environment might change in the absence of new measures to alleviate debris proliferation, examine ongoing alleviation activities, explore measures to address the problem, and develop recommendations on technical methods to address the problems of debris proliferation.

  6. Dynamic modeling and control of a solid-sorbent CO{sub 2} capture process with two-stage bubbling fluidized bed adsorber reactor

    SciTech Connect

    Modekurti, S.; Bhattacharyya, D.; Zitney, S.

    2012-01-01

    Solid-sorbent-based CO{sub 2} capture processes have strong potential for reducing the overall energy penalty for post-combustion capture from the flue gas of a conventional pulverized coal power plant. However, the commercial success of this technology is contingent upon it operating over a wide range of capture rates, transient events, malfunctions, and disturbances, as well as under uncertainties. To study these operational aspects, a dynamic model of a solid-sorbent-based CO{sub 2} capture process has been developed. In this work, a one-dimensional (1D), non-isothermal, dynamic model of a two-stage bubbling fluidized bed (BFB) adsorber-reactor system with overflow-type weir configuration has been developed in Aspen Custom Modeler (ACM). The physical and chemical properties of the sorbent used in this study are based on a sorbent (32D) developed at National Energy Technology Laboratory (NETL). Each BFB is divided into bubble, emulsion, and cloud-wake regions with the assumptions that the bubble region is free of solids while both gas and solid phases coexist in the emulsion and cloud-wake regions. The BFB dynamic model includes 1D partial differential equations (PDEs) for mass and energy balances, along with comprehensive reaction kinetics. In addition to the two BFB models, the adsorber-reactor system includes 1D PDE-based dynamic models of the downcomer and outlet hopper, as well as models of distributors, control valves, and other pressure-drop devices. Consistent boundary and initial conditions are considered for simulating the dynamic model. Equipment items are sized and appropriate heat transfer options, wherever needed, are provided. Finally, a valid pressure-flow network is developed and a lower-level control system is designed. Using ACM, the transient responses of various process variables such as flue gas and sorbent temperatures, overall CO{sub 2} capture, level of solids in the downcomer and hopper have been studied by simulating typical

  7. Orbital Debris Modeling

    NASA Technical Reports Server (NTRS)

    Liou, J. C.

    2012-01-01

    Presentation outlne: (1) The NASA Orbital Debris (OD) Engineering Model -- A mathematical model capable of predicting OD impact risks for the ISS and other critical space assets (2) The NASA OD Evolutionary Model -- A physical model capable of predicting future debris environment based on user-specified scenarios (3) The NASA Standard Satellite Breakup Model -- A model describing the outcome of a satellite breakup (explosion or collision)

  8. Characterization of Debris from the DebriSat Hypervelocity Test

    NASA Technical Reports Server (NTRS)

    Rivero, M.; Kleespies, J.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.; Opiela, J.; Krisko, P.; Cowardin, H.

    2015-01-01

    The DebriSat project is an effort by NASA and the DoD to update the standard break-up model for objects in orbit. The DebriSat object, a 56 kg representative LEO satellite, was subjected to a hypervelocity impact in April 2014. For the hypervelocity test, the representative satellite was suspended within a "soft-catch" arena formed by polyurethane foam panels to minimize the interactions between the debris generated from the hypervelocity impact and the metallic walls of the test chamber. After the impact, the foam panels and debris not caught by the panels were collected and shipped to the University of Florida where the project has now advanced to the debris characterization stage. The characterization effort has been divided into debris collection, measurement, and cataloguing. Debris collection and cataloguing involves the retrieval of debris from the foam panels and cataloguing the debris in a database. Debris collection is a three-step process: removal of loose debris fragments from the surface of the foam panels; X-ray imaging to identify/locate debris fragments embedded within the foam panel; extraction of the embedded debris fragments identified during the X-ray imaging process. As debris fragments are collected, they are catalogued into a database specifically designed for this project. Measurement involves determination of size, mass, shape, material, and other physical properties and well as images of the fragment. Cataloguing involves a assigning a unique identifier for each fragment along with the characterization information.

  9. Method and apparatus for a combination moving bed thermal treatment reactor and moving bed filter

    SciTech Connect

    Badger, Phillip C.; Dunn, Jr., Kenneth J.

    2015-09-01

    A moving bed gasification/thermal treatment reactor includes a geometry in which moving bed reactor particles serve as both a moving bed filter and a heat carrier to provide thermal energy for thermal treatment reactions, such that the moving bed filter and the heat carrier are one and the same to remove solid particulates or droplets generated by thermal treatment processes or injected into the moving bed filter from other sources.

  10. Space Debris & its Mitigation

    NASA Astrophysics Data System (ADS)

    Kaushal, Sourabh; Arora, Nishant

    2012-07-01

    Space debris has become a growing concern in recent years, since collisions at orbital velocities can be highly damaging to functioning satellites and can also produce even more space debris in the process. Some spacecraft, like the International Space Station, are now armored to deal with this hazard but armor and mitigation measures can be prohibitively costly when trying to protect satellites or human spaceflight vehicles like the shuttle. This paper describes the current orbital debris environment, outline its main sources, and identify mitigation measures to reduce orbital debris growth by controlling these sources. We studied the literature on the topic Space Debris. We have proposed some methods to solve this problem of space debris. We have also highlighted the shortcomings of already proposed methods by space experts and we have proposed some modification in those methods. Some of them can be very effective in the process of mitigation of space debris, but some of them need some modification. Recently proposed methods by space experts are maneuver, shielding of space elevator with the foil, vaporizing or redirecting of space debris back to earth with the help of laser, use of aerogel as a protective layer, construction of large junkyards around international space station, use of electrodynamics tether & the latest method proposed is the use of nano satellites in the clearing of the space debris. Limitations of the already proposed methods are as follows: - Maneuvering can't be the final solution to our problem as it is the act of self-defence. - Shielding can't be done on the parts like solar panels and optical devices. - Vaporizing or redirecting of space debris can affect the human life on earth if it is not done in proper manner. - Aerogel has a threshold limit up to which it can bear (resist) the impact of collision. - Large junkyards can be effective only for large sized debris. In this paper we propose: A. The Use of Nano Tubes by creating a mesh

  11. SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head

    SciTech Connect

    Siefken, Larry James; Harvego, Edwin Allan

    2000-04-01

    A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head.

  12. SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head

    SciTech Connect

    L. J. Siefken; E. A. Harvego

    2000-04-02

    A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head.

  13. STS-51-L Recovered Debris (Orbiter)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    On January 28, 1986, the Space Shuttle Challenger and her seven-member crew were lost when a ruptured O-ring in the right Solid Rocket Booster caused an explosion soon after launch. After the accident, search and recovery teams worked for months to bring debris from Shuttle to impoundment areas at the Kennedy Space Center and the Cape Canaveral Air Force Station, where reconstruction teams separated the pieces of the orbiter from those of the External Tank and the Solid Rocket Boosters. Taped squares on the floor turned the impoundment areas into a grid in which the reconstruction teams could piece together the Shuttle debris like a puzzle with many missing segments. Shown here is the reassembled Orbiter.

  14. Experimental Modelling of Debris Flows

    NASA Astrophysics Data System (ADS)

    Paleo Cageao, P.; Turnbull, B.; Bartelt, P.

    2012-04-01

    Debris flows are gravity-driven mass movements typically containing water, sediments, soil and rocks. These elements combine to give a flow complex phenomenology that exhibits characteristics common to diverse geophysical flows from dry granular media (e.g. levee formation) to viscous gravity currents (viscous fingering and surge instabilities). The exceptional speeds and range debris flows can achieve motivate the need for a co-ordinated modelling approach that can provide insight into the key physical processes that dictate the hazard associated with the flows. There has been recent progress in theoretical modelling approaches that capture the details of the multi-component nature of debris flows. The promise of such models is underlined by their qualitatively successful comparison with field-scale experimental data. The aim of the present work is to address the technical difficulties in achieving a controlled and repeatable laboratory-scale experiment for robust testing of these multi-component models. A laboratory experiment has been designed and tested that can provide detailed information of the internal structure of debris flows. This constitutes a narrow Perspex chute that can be tilted to any angle between 0° and ≈ 60°. A mixture of glycerine and glass balls was initially held behind a lock-gate, before being released down the chute. The evolving flow was captured through high speed video, analysed with a Particle Image Velocimetry algorithm to provide the changing velocity field. A wide parameter space has been tested, allowing variations in particle size, dispersity, surface roughness, fluid viscosity, slope angle and solid volume fraction. While matching key similarity criteria, such as Froude number, with a typical field event, these experiments allow close examination of a wide range of physical scenarios for the robust testing of new multi-component flow models. Further diagnostics include force plate and pore pressure measurements, with a view

  15. Research On Rainfall and The Prediction of Debris Flow

    NASA Astrophysics Data System (ADS)

    Yu, B.

    Accurate prediction of debris flow so that economic losses and human ca- sualties can be reduced or prevented is currently the most focused and difficult point of studying debris flows. Most predictive methods have relied on rainfall as the basic parameter to make predictions, with the result that there is only the prediction of the actual occurrence without that of its arrival time and scale. This article takes Jiangjia Gully in Dongchuan of Yunnan Province as an example, and considers, on the basis of the already possessed essential condition U solid material, the abundant conditions for ° the formation of debris flow. Based on the mechanism of the occurrence of debris flow and the volume of rainfall in the basin, this paper also gives a systematic analysis on the arrival time and scale of debris flow, and suggests that the hydrological condition for forming debris flow is the unit discharge of the flood 8805; 0.35m2/s.m. It uses the ten-minute rainfall intensity to calculate both the runoffs of the rainfall and the unit discharge from the runoff, thus predicting the occurrence of debris flow. The velocity and the arrival time of a debris flow can be figured out by using the unit discharge of the runoffs. The total amount of debris flow can be calculated out and the scale of a debris flow can be predicted by using the ten-minute intensity of rainfall and the total volume of the runoffs, together with the volume concentration of sediment in a debris flow and the basin block up coefficient.

  16. Benefits of Active Debris Removal on the LEO Debris Population

    NASA Astrophysics Data System (ADS)

    Maniwa, Kazuaki; Hanada, Toshiya; Kawamoto, Satomi

    Since the launch of Sputnik, orbital debris population continues to increase due to ongoing space activities, on-orbit explosions, and accidental collisions. In the future, a great deal of fragments can be expected to be created by explosions and collisions. In spite of prevention of satellite and rocket upper stage explosions and other mitigation measures, debris population in low Earth orbit may not be stabilized. To better limit the growth of the future debris population, it is necessary to remove the existing debris actively. This paper studies about the effectiveness of active debris removal in low Earth orbit where the collision rate with and between space debris is high. This study does not consider economic problems, but investigates removing debris which may stabilize well the current debris population based on the concept of Japan Aerospace Exploration Agency.

  17. Space debris detection

    NASA Astrophysics Data System (ADS)

    Eather, Robert H.

    1992-12-01

    A feasibility study on the possibility of detecting less than or = 10 cm space debris using a large-aperture ground-based telescope (with an intensified CCD detector) was completed, showing that detection should be possible. A detector system was designed and built, and installed on the 2.54 m WRDC telescope at Wright Patterson AFB. Bad seeing conditions in the Dayton area prevented the expected debris detection. Subsequently, a small 40 cm telescope was built and operated from the Haystack Observatory (Groton, MA). Known objects were used to test pointing and acquisition procedures, and the system was then shipped to Rattlesnake Observatory (Richland, WA) for participation in the ODERAC's debris calibration experiment from the Space Shuttle. This experiment failed, and our instrument has been stored at Rattlesnake in anticipation of a new ODERAC's flight in late 1993.

  18. 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.

  19. Meteoroid/Debris Shielding

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2003-01-01

    This report provides innovative, low-weight shielding solutions for spacecraft and the ballistic limit equations that define the shield's performance in the meteoroid/debris environment. Analyses and hypervelocity impact testing results are described that have been used in developing the shields and equations. Spacecraft shielding design and operational practices described in this report are used to provide effective spacecraft protection from meteoroid and debris impacts. Specific shield applications for the International Space Station (ISS), Space Shuttle Orbiter and the CONTOUR (Comet Nucleus Tour) space probe are provided. Whipple, Multi-Shock and Stuffed Whipple shield applications are described.

  20. Field observations of particle impacts by debris flows and debris floods on instrumented rock samples

    NASA Astrophysics Data System (ADS)

    McArdell, B. W.; Hsu, L.; Fritschi, B.; Dietrich, W. E.

    2011-12-01

    Bedrock incision and sediment entrainment by debris flows are important processes in torrent channels. As part of our effort to gain a better understanding of these processes, we installed instrumented rock samples in the bed of the Illgraben channel. Three rock samples, 0.4 m long (in the flow direction), 0.3 m wide, and 0.2 m thick, were installed in steel frames which were mounted on the upslope side of a concrete check dam, with the surface of the stones flush with the channel bed. Accelerometer sensors were installed on the bottom of one rock sample, with a range of up to 500 g (vertical) and 200 g (horizontal, parallel to the channel axis), where g is the acceleration due to gravity. Elastomer elements, typically used in the field as overload protection for load sensors, were placed between the rock samples and the steel frames. Data were sampled at 2 kHz and stored on a computer outside of the channel. The sensors provided data for 4 debris floods and part of one debris flow. For all of the events, the vertical acceleration data indicate a large background noise in the range of ±10 g, punctuated by very short duration impulses of up to several hundred g. The large accelerations are interpreted to represent hard impacts of cobbles or boulders in the flow with the rock tablet. Using a value of >20 g to define the occurrence of a large particle impact, it is possible to differentiate between debris floods (which have on the order of 0.1 impact per second) and the debris flow (on the order of 1 impact per second). The frequency of the sampling is too small to resolve details about the impacts, so it is not possible to precisely determine the maximum accelerations. However the peak recorded values are larger for debris flows, with values up to the measurement limit of the sensors, whereas for floods the maximum accelerations are typically less than 100 g. The results for the accelerometer which measures accelerations in the downstream direction generally mirror

  1. Staged cascade fluidized bed combustor

    DOEpatents

    Cannon, Joseph N.; De Lucia, David E.; Jackson, William M.; Porter, James H.

    1984-01-01

    A fluid bed combustor comprising a plurality of fluidized bed stages interconnected by downcomers providing controlled solids transfer from stage to stage. Each stage is formed from a number of heat transfer tubes carried by a multiapertured web which passes fluidizing air to upper stages. The combustor cross section is tapered inwardly from the middle towards the top and bottom ends. Sorbent materials, as well as non-volatile solid fuels, are added to the top stages of the combustor, and volatile solid fuels are added at an intermediate stage.

  2. Orbital Debris: A Policy Perspective

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2007-01-01

    A viewgraph presentation describing orbital debris from a policy perspective is shown. The contents include: 1) Voyage through near-Earth Space-animation; 2) What is Orbital Debris?; 3) Orbital Debris Detectors and Damage Potential; 4) Hubble Space Telescope; 5) Mir Space Station Solar Array; 6) International Space Station; 7) Space Shuttle; 8) Satellite Explosions; 9) Satellite Collisions; 10) NASA Orbital Debris Mitigation Guidelines; 11) International Space Station Jettison Policy; 12) Controlled/Uncontrolled Satellite Reentries; 13) Return of Space Objects; 14) Orbital Debris and U.S. National Space Policy; 15) U.S Government Policy Strategy; 16) Bankruptcy of the Iridium Satellite System; 17) Inter-Agency Space Debris Coordination Committee (IADC); 18) Orbital Debris at the United Nations; 19) Chinese Anti-satellite System; 20) Future Evolution of Satellite Population; and 21) Challenge of Orbital Debris

  3. Trace element-bearing phases during the solid transport: in-situ characterization and temporal variability in the Loire bed-sediments (France)

    NASA Astrophysics Data System (ADS)

    Grosbois, Cécile; Courtin-Nomade, Alexandra; Dhivert, Elie; Desmet, Marc; Kunz, Martin

    2013-04-01

    As a result of increased of agriculture, land use, urban areas, industry, traffic and population density, trace element inputs have altered considerably fluvial system (sediment, water quality and biota). The Loire River Basin (117,800 km2, total population of 8.4 Mp in 2010), even if it is considered one of the least human-impacted hydrosystem among the 5 large French basins, has been exposed to multiple sources of metals during the last 150 years, originating from major mining districts (coal and non-ferrous metals) and their associated industrial activities (Grosbois et al, 2012; Dhivert et al, 2013). Two major contamination periods were recorded in several core sediments throughout the basin: <1900-1950, an early contamination period, mainly associated to intensive coal use and metal mining and 1950-1980, a severe contamination period related to industrial and ore-processing activities superimposed to urban development of the basin. The limited dilution by detrital material (Loire sediment load between1.5 and 3.5 Mt/y) was an additional cause of such severe contamination. After 1950, river eutrophication was well-marked by the general increase of endogenic calcite in the mid and downstream part of the basin, slightly diluting all major and trace element bulk concentrations by 20% (Grosbois et al, 2012). Since 1980, a generalized and gradual decontamination of bed sediments started while mines were gradually closing, urban waste waters collected and treated in addition to new environmental regulations. They aim to limit metallic pollutant dispersion like industrial recycling of metal wastes and to reduce atmospheric emissions and consequently atmospheric fall out wet and dry deposition In-situ chemical and mineralogical techniques (EPMA, SEM-EDS/ACC system and synchrotron based µXRD) were used (i) to highlight anthropogenic activities by a specific mineralogical signature and (ii) to determine potential effects of post-depositional remobilization and access

  4. Systems and Sensors for Debris-flow Monitoring and Warning

    PubMed Central

    Arattano, Massimo; Marchi, Lorenzo

    2008-01-01

    Debris flows are a type of mass movement that occurs in mountain torrents. They consist of a high concentration of solid material in water that flows as a wave with a steep front. Debris flows can be considered a phenomenon intermediate between landslides and water floods. They are amongst the most hazardous natural processes in mountainous regions and may occur under different climatic conditions. Their destructiveness is due to different factors: their capability of transporting and depositing huge amounts of solid materials, which may also reach large sizes (boulders of several cubic meters are commonly transported by debris flows), their steep fronts, which may reach several meters of height and also their high velocities. The implementation of both structural and non-structural control measures is often required when debris flows endanger routes, urban areas and other infrastructures. Sensor networks for debris-flow monitoring and warning play an important role amongst non-structural measures intended to reduce debris-flow risk. In particular, debris flow warning systems can be subdivided into two main classes: advance warning and event warning systems. These two classes employ different types of sensors. Advance warning systems are based on monitoring causative hydrometeorological processes (typically rainfall) and aim to issue a warning before a possible debris flow is triggered. Event warning systems are based on detecting debris flows when these processes are in progress. They have a much smaller lead time than advance warning ones but are also less prone to false alarms. Advance warning for debris flows employs sensors and techniques typical of meteorology and hydrology, including measuring rainfall by means of rain gauges and weather radar and monitoring water discharge in headwater streams. Event warning systems use different types of sensors, encompassing ultrasonic or radar gauges, ground vibration sensors, videocameras, avalanche pendulums

  5. A real two-phase submarine debris flow and tsunami

    NASA Astrophysics Data System (ADS)

    Pudasaini, Shiva P.; Miller, Stephen A.

    2012-09-01

    The general two-phase debris flow model proposed by Pudasaini [1] is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the

  6. A real two-phase submarine debris flow and tsunami

    SciTech Connect

    Pudasaini, Shiva P.; Miller, Stephen A.

    2012-09-26

    The general two-phase debris flow model proposed by Pudasaini is employed to study subaerial and submarine debris flows, and the tsunami generated by the debris impact at lakes and oceans. The model, which includes three fundamentally new and dominant physical aspects such as enhanced viscous stress, virtual mass, and generalized drag (in addition to buoyancy), constitutes the most generalized two-phase flow model to date. The advantage of this two-phase debris flow model over classical single-phase, or quasi-two-phase models, is that the initial mass can be divided into several parts by appropriately considering the solid volume fraction. These parts include a dry (landslide or rock slide), a fluid (water or muddy water; e.g., dams, rivers), and a general debris mixture material as needed in real flow simulations. This innovative formulation provides an opportunity, within a single framework, to simultaneously simulate the sliding debris (or landslide), the water lake or ocean, the debris impact at the lake or ocean, the tsunami generation and propagation, the mixing and separation between the solid and fluid phases, and the sediment transport and deposition process in the bathymetric surface. Applications of this model include (a) sediment transport on hill slopes, river streams, hydraulic channels (e.g., hydropower dams and plants); lakes, fjords, coastal lines, and aquatic ecology; and (b) submarine debris impact and the rupture of fiber optic, submarine cables and pipelines along the ocean floor, and damage to offshore drilling platforms. Numerical simulations reveal that the dynamics of debris impact induced tsunamis in mountain lakes or oceans are fundamentally different than the tsunami generated by pure rock avalanches and landslides. The analysis includes the generation, amplification and propagation of super tsunami waves and run-ups along coastlines, debris slide and deposition at the bottom floor, and debris shock waves. It is observed that the

  7. Space Debris Mitigation Guidelines

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2011-01-01

    The purpose of national and international space debris mitigation guides is to promote the preservation of near-Earth space for applications and exploration missions far into the future. To accomplish this objective, the accumulation of objects, particularly in long-lived orbits, must be eliminated or curtailed.

  8. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker Jr., Louis

    1986-07-01

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  9. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, J.D.; Cassulo, J.C.; Pedersen, D.R.; Baker, L. Jr.

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and can be discharged from the reactor core. The invention provides a porous bed of sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  10. Safety apparatus for nuclear reactor to prevent structural damage from overheating by core debris

    DOEpatents

    Gabor, John D.; Cassulo, John C.; Pedersen, Dean R.; Baker, Jr., Louis

    1986-01-01

    The invention teaches safety apparatus that can be included in a nuclear reactor, either when newly fabricated or as a retrofit add-on, that will minimize proliferation of structural damage to the reactor in the event the reactor is experiencing an overheating malfunction whereby radioactive nuclear debris might break away from and be discharged from the reactor core. The invention provides a porous bed or sublayer on the lower surface of the reactor containment vessel so that the debris falls on and piles up on the bed. Vapor release elements upstand from the bed in some laterally spaced array. Thus should the high heat flux of the debris interior vaporize the coolant at that location, the vaporized coolant can be vented downwardly to and laterally through the bed to the vapor release elements and in turn via the release elements upwardly through the debris. This minimizes the pressure buildup in the debris and allows for continuing infiltration of the liquid coolant into the debris interior.

  11. Fluidized bed catalytic coal gasification process

    DOEpatents

    Euker, Jr., Charles A.; Wesselhoft, Robert D.; Dunkleman, John J.; Aquino, Dolores C.; Gouker, Toby R.

    1984-01-01

    Coal or similar carbonaceous solids impregnated with gasification catalyst constituents (16) are oxidized by contact with a gas containing between 2 volume percent and 21 volume percent oxygen at a temperature between 50.degree. C. and 250.degree. C. in an oxidation zone (24) and the resultant oxidized, catalyst impregnated solids are then gasified in a fluidized bed gasification zone (44) 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.

  12. GEO Debris Observation of PMO

    NASA Astrophysics Data System (ADS)

    Ping, Yiding; Zhao, Changyin; Zhao, Haibin

    2009-03-01

    This paper summarizes observations and results obtained by Purple Mountain Observatory in March 2007 of space debris at geosynchronous orbit (GEO) in support of WG1 Action Item 23.4, International 2007 Optical Debris Campaign in Higher Earth Orbit, organized by the Inter-Agency Space Debris Coordination Committee (IADC). The main goal of Pmo's work is to develop the observational techniques of Higher Earth Orbit Space debris for the future work. A new telescope designed for debris observation is also described here.

  13. Dual fluidized bed design for the fast pyrolysis of biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mechanism for the transport of solids between fluidised beds in dual fluidised bed systems for the fast pyrolysis of biomass process was selected. This mechanism makes use of an overflow standpipe to transport solids from the fluidised bed used for the combustion reactions to a second fluidised be...

  14. Experimental verification of an innovative debris detector

    NASA Astrophysics Data System (ADS)

    Bauer, Waldemar; Romberg, Oliver; Putzar, Robin

    2015-12-01

    To analyse the quantity of space debris and micrometeoroids in space, an innovative in-situ impact detection method has been developed at DLR (German Aerospace Center) in Bremen, Germany. The method Solar generator based Impact Detector "SOLID" uses solar panels for impact detection. Since solar panels provide large detection areas, this method allows for the collection of large amounts of data, to be used also for model validation. Furthermore, impact damage can be verified once more to confirm or to refute an impact. Both aspects can significantly improve the quality of model validation by using large amounts of highly reliable data. A verification of the detection method was performed by Hypervelocity Impact (HVI) tests at Fraunhofer EMI, Freiburg, Germany. The HVI tests were conducted using projectiles with a diameter between 500 μm and 2 mm. The impact velocity of those objects ranged from 3.9 km/s to 6.2 km/s. The objective of this investigation was to test the applicability of the developed method concerning in-situ detection of space debris and micrometeoroids. The achieved test results are in agreement with ESA developed damage equations. The ability of the detection method SOLID for impact detection of space debris and micrometeoroids was clearly demonstrated.

  15. The Transportation of Debris by Running Water

    USGS Publications Warehouse

    Gilbert, Grove Karl; Murphy, Edward Charles

    1914-01-01

    Scope.-The finer debris transported by a stream is borne in suspension. The coarser is swept along the channel bed. The suspended load is readily sampled and estimated, and much is known as to its quantity. The bed load is inaccessible and we are without definite information as to its amount. The primary purpose of the investigation was to learn the laws which control the movement of bed load, and especially to determine how the quantity of load is related to the stream's slope and discharge and to the degree of comminution of the debris. Method.-To this end a laboratory was equipped at Berkeley, Cal., and experiments were performed in which each of the three conditions mentioned was separately varied and the resulting variations of load were observed and measured. Sand and gravel were sorted by sieves into grades of uniform size. Determinate discharges were used. In each experiment a specific load was fed to a stream of specific width and discharge, and measurement was made of the slope to which the stream automatically adjusted its bed so as to enable the current to transport the load. The slope factor.-For each combination of discharge, width, and grade of debris there is a slope, called competent slope, which limits transportation. With lower slopes there is no load, or the stream has no capacity for load. With higher slopes capacity exists; and increase of slope gives increase of capacity. The value of capacity is approximately proportional to a power of the excess of slope above competent slope. If S equal the stream's slope and sigma equal competent slope, then the stream's capacity varies as (S - sigma)n. This is not a deductive, but an empiric law. The exponent n has not a fixed value, but an indefinite series of values depending on conditions. Its range of values in the experience of the laboratory is from 0.93 to 2.37, the values being greater as the discharges are smaller or the debris is coarser. The discharge factor.-For each combination of width

  16. Floating junk bonnet protects liner top from debris

    SciTech Connect

    Telfer, G. ); Sweeney, D. )

    1994-09-12

    A new design of debris protection system, the floating junk bonnet, for liner tops prevents well debris from entering the liner top polished bore receptacle (PBR) and sticking the setting tools. The floating junk bonnet improves the recovery of liner setting tools from the well no matter how severe the debris problem is. Well debris (formation cuttings, fines, mud solids, cement solids, foreign bodies, etc) entering the linear top PBR during cementing operations has been a serious problem for many operators. In some cases, this problem has led to liner hanger setting tools sticking in the liner top PBR. The setting tool could then become cemented in place, resulting in an expensive fishing job or sidetrack. A prototype debris protection system was developed and tested prior to offshore application. The liner protection tool was subsequently successfully used on Nelson project development wells in the U.K. North Sea. The paper discusses debris accumulation, the junket basket, the floating junk bonnet design, test procedures, and field test results.

  17. Evaluating tsunami hazards from debris flows

    NASA Astrophysics Data System (ADS)

    Walder, J.; Watts, P.

    2003-04-01

    Water-wave hazards associated with debris flows entering water depend on the location of the affected area relative to the debris-flow entry point. Three distinct regions (splash zone, near field, and far field) may be identified may be identified on hydrodynamic grounds. The splash zone is nearly always small compared to the overall domain of interest. In the case of debris-flow generated tsunamis in lakes and reservoirs, commonly the entire water body lies within the near field, that is, beyond the zone of complex splashing but close enough to the source that wave-propagation effects do not predominate, in contrast to the case of tsunamis in the ocean. Scaling analysis of the equations governing water-wave propagation shows that near-field wave amplitude and wavelength should depend on specific measures of debris-flow dynamics and volume. The scaling analysis motivates a successful collapse (in dimensionless space) of data from two sets of flume experiments with solid-block "wavemakers." To first order, measured near-field wave amplitude/water depth depends simply on a dimensionless measure of the quantity (submerged travel time/wavemaker volume per unit width). This functional relationship also does a good job of describing wave-amplitude data from previous laboratory investigations with both rigid and deformable wavemakers. The characteristic wavelength/water depth for all our experiments is simply proportional to dimensionless wavemaker travel time, which is itself given approximately by a simple function of wavemaker length/water depth. Wavemaker shape and rigidity do not otherwise influence wave features. These scaling relations for near-field amplitude, wavelength, and submerged travel time, when combined with a correction for near-field wavefront speading in actual water bodies (which are rarely flume-like), allow us to construct a proxy source for computational tsunami propagation. We apply our results to assess hazards associated with potential debris

  18. Estimating rates of debris flow entrainment from ground vibrations

    NASA Astrophysics Data System (ADS)

    Kean, J. W.; Coe, J. A.; Coviello, V.; Smith, J. B.; McCoy, S. W.; Arattano, M.

    2015-08-01

    Debris flows generate seismic waves as they travel downslope and can become more dangerous as they entrain sediment along their path. We present field observations that show a systematic relation between the magnitude of seismic waves and the amount of erodible sediment beneath the flow. Specifically, we observe that a debris flow traveling along a channel filled initially with sediment 0.34 m thick generates about 2 orders of magnitude less spectral power than a similar-sized flow over the same channel without sediment fill. We adapt a model from fluvial seismology to explain this observation and then invert it to estimate the level of bed sediment (and rate of entrainment) beneath a passing series of surges. Our estimates compare favorably with previous direct measurements of entrainment rates at the site, suggesting the approach may be a new indirect way to obtain rare field constraints needed to test models of debris flow entrainment.

  19. Orbital debris measurements

    NASA Technical Reports Server (NTRS)

    Kessler, D. J.

    1986-01-01

    What is currently known about the orbital debris flux is from a combination of ground based and in-space measurements. These measurements have revealed an increasing population with decreasing size. A summary of measurements is presented for the following sources: the North American Aerospace Defense Command Catalog, the Perimeter Acquisition and Attack Characterization System Radar, ground based optical telescopes, the Explorer 46 Meteoroid Bumper Experiment, spacecraft windows, and Solar Max surfaces.

  20. Measuring and modeling solids movement in a large, cold fluidized bed test facility. Third quarterly report, April 1-June 30, 1980

    SciTech Connect

    Fitzgerald, T. J.; Mrazek, R. V.; Crane, S. D.

    1980-06-01

    A considerable fraction of the apparent gas dispersion coefficient of a fluidized bed is due to a non-dispersive meander of the bed gas as it travels up through the bed. The experimental results indicate that a dispersion coefficient which is obtained by measuring the time average concentration at some location in the bed and then comparing the concentration to the tracer inlet rate will overestimate the real turbulent/molecular dispersion coefficient by as much as 60 to 70%. The meander coefficient was observed to vary from 0.0005 ft/sup 2//sec at a superficial velocity of 1.5 ft/sec (about 1.9 u/sub 0//u/sub mf/) to about 0.068 ft/sup 2//sec at an air velocity of 6.0 ft/sec. The corresponding range in the turbulent/molecular dispersion coefficient was 0.004 ft/sup 2//sec to 0.10 ft/sup 2//sec. The meander coefficient shows a continued increase with air velocity whereas the turbulent/molecular coefficient was very close to the same value for the two highest velocities. There is some weak evidence of anisotropy in the meander dispersion coefficient. The turbulent/molecular coefficient seems to be independent of location.

  1. Material Density Distribution of Small Debris in Earth Orbit

    NASA Technical Reports Server (NTRS)

    Krisko, P. H.; Xu, Y.-l.; Opiela, J. N.; Hill, N. M.; Matney, M. J.

    2008-01-01

    Over 200 spacecraft and rocket body breakups in Earth orbit have populated that regime with debris fragments in the sub-micron through meter size range. Though the largest debris fragments can cause significant collisional damage to active (operational) spacecraft, these are few and trackable by radar. Fragments on the order of a millimeter to a centimeter in size are as yet untrackable. But this smaller debris can result in damage to critical spacecraft systems and, under the worst conditions, fragmenting collision events. Ongoing research at the NASA Orbital Debris Program Office on the sources of these small fragments has focused on the material components of spacecraft and rocket bodies and on breakup event morphology. This has led to fragment material density estimates, and also the beginnings of shape categorizations. To date the NASA Standard Breakup Model has not considered specific material density distinctions of small debris. The basis of small debris in that model is the fourth hypervelocity impact event of the Satellite Orbital Debris Characterization Impact Test (SOCIT) series. This test targeted a flight-ready, U.S. Transit navigation satellite with a solid aluminum sphere impactor. Results in this event yield characteristic length (size) and area-to-mass distributions of fragments smaller than 10 cm in the NASA model. Recent re-analysis of the SOCIT4 small fragment dataset highlighted the material-specific characteristics of metals and non-metals. Concurrent analysis of Space Shuttle in-situ impact data showed a high percentage of aluminum debris in shuttle orbit regions. Both analyses led to the definition of three main on-orbit debris material density categories -low density (< 2 g/cc), medium density (2 to 6 g/cc), and high density (> 6 g/cc). This report considers the above studies in an explicit extension of the NASA Standard Breakup Model where separate material densities for debris are generated and these debris fragments are propagated in

  2. Space Debris Modeling at NASA

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2001-01-01

    Since the Second European Conference on Space Debris in 1997, the Orbital Debris Program Office at the NASA Johnson Space Center has undertaken a major effort to update and improve the principal software tools employed to model the space debris environment and to evaluate mission risks. NASA's orbital debris engineering model, ORDEM, represents the current and near-term Earth orbital debris population from the largest spacecraft to the smallest debris in a manner which permits spacecraft engineers and experimenters to estimate the frequency and velocity with which a satellite may be struck by debris of different sizes. Using expanded databases and a new program design, ORDEM2000 provides a more accurate environment definition combined with a much broader array of output products in comparison with its predecessor, ORDEM96. Studies of the potential long-term space debris environment are now conducted with EVOLVE 4.0, which incorporates significant advances in debris characterization and breakup modeling. An adjunct to EVOLVE 4.0, GEO EVOLVE has been created to examine debris issues near the geosynchronous orbital regime. In support of NASA Safety Standard 1740.14, which establishes debris mitigation guidelines for all NASA space programs, a set of evaluation tools called the Debris Assessment Software (DAS) is specifically designed for program offices to determine whether they are in compliance with NASA debris mitigation guidelines. DAS 1.5 has recently been released with improved WINDOWS compatibility and graphics functions. DAS 2.0 will incorporate guideline changes in a forthcoming revision to NASA Safety Standard 1740.14. Whereas DAS contains a simplified model to calculate possible risks associated with satellite reentries, NASA's higher fidelity Object Reentry Survival Analysis Tool (ORSAT) has been upgraded to Version 5.0. With the growing awareness of the potential risks posed by uncontrolled satellite reentries to people and property on Earth, the

  3. Critical Rainfall Conditions Triggering Shallow Landslides or Debris Flows in Torrents - Analysis of Debris Flow events 2012, 2013 and 2014 in Austria

    NASA Astrophysics Data System (ADS)

    Moser, Markus; Mehlhorn, Susanne; Janu, Stefan

    2015-04-01

    Generally, debris flows are caused by both small-scale intensive precipitation and long lasting rainfalls with lower intensity but high pre-wetting or both combined. The triggering mechanism of the debris flow events in Austria 2012, 2013 and 2014 were mass movements (rapid shallow landslides) on steep slopes in the upper catchments. Those masses slide with very high velocity into the torrent beds provoking hyperconcentrated flows or debris flows. In areas of the geologically unstable Greywacke zone, the torrents were cleared up onto the bedrock and the debris was deposited in the storage areas of existing debris flow breakers or in torrents without technical protection measures the debris caused catastrophic damage to residential buildings and other infrastructural facilities on the alluvial fan. Following the events, comprehensive documentation work was undertaken comprising precipitation analysis (rainfall data, weather radar data), identification and quantification of the landslide masses, cross profiles along the channel and of deposition in the storage areas or on the fan. The documentation and analysis of torrential events is an essential part of an integrated risk management. It supports the understanding of the occurred processes to mitigate future hazards. Unfortunately, the small-scale heavy rain events are not detected by the precipitation stations. Therefore, weather radar data (INCA-Data) analysis was used to determine the - usually very local - intensities which caused those catastrophic landslides and debris flows. Analysis results showed an agreement with the range of the previously known precipitation thresholds for debris flow triggering in the Alps.

  4. Laboratory study of the underground sound generated by debris flows

    NASA Astrophysics Data System (ADS)

    Huang, Ching-Jer; Shieh, Chieng-Lun; Yin, Hsiao-Yuan

    2004-03-01

    This experimental study investigates the underground sound generated by different kinds of rock motions that occur in debris flows. The experiments were divided into two parts. The first part consisted of measuring the main characteristics of the underground sound caused by friction of a rock rubbed against a bed of gravel and of that caused by a free-falling rock hitting a similar bed of gravel. In the second part a hydrophone was installed at the bottom of a laboratory channel to measure the underground sound of debris flows in that channel. The sound signals were analyzed using both the fast Fourier transform and the Gabor transform to represent the signals in both the frequency and time-frequency domains. The measurement results reveal that the frequency of the sound generated by the rock-gravel bed friction is relatively low, being mostly between 20 and 80 Hz. In contrast, the frequency range of the collision sound is relatively higher, between 10 and 500 Hz. Finally, the frequency of the underground sound caused by the debris flows in the flume is in the range of 20-300 Hz.

  5. Method of burning sulfur-containing fuels in a fluidized bed boiler

    DOEpatents

    Jones, Brian C.

    1982-01-01

    A method of burning a sulfur-containing fuel in a fluidized bed of sulfur oxide sorbent wherein the overall utilization of sulfur oxide sorbent is increased by comminuting the bed drain solids to a smaller average particle size, preferably on the order of 50 microns, and reinjecting the comminuted bed drain solids into the bed. In comminuting the bed drain solids, particles of spent sulfur sorbent contained therein are fractured thereby exposing unreacted sorbent surface. Upon reinjecting the comminuted bed drain solids into the bed, the newly-exposed unreacted sorbent surface is available for sulfur oxide sorption, thereby increasing overall sorbent utilization.

  6. Field observations of a debris flow event in the Dolomites

    NASA Astrophysics Data System (ADS)

    Berti, Matteo; Genevois, Rinaldo; Simoni, Alessandro; Tecca, Pia Rosella

    1999-09-01

    A debris flow event occurred in June 1997 in the Dolomites (Eastern Alps, Italy). The phenomenon was directly observed in the field and recorded by a video camera near its initiation area. The debris flow originated shortly after an intense rainstorm (25 mm in 30 min) whose runoff mobilised the loose coarse debris that filled the bottom of the channel in its upper part. The analysis of the steep headwater basin indicates a very short concentration time (9-14 min) that fits the quick hydrological response observed in the field. The debris flow mobilisation was not contemporaneous with the arrival of the peak water discharge in the initiation area probably due to the time required for the saturation of the highly conductive channel-bed material. Channel cross-section measurements taken along the flow channel indicate debris flow peak velocity and discharge ranging from 3.1 to 9.0 m/s and from 23 to 71 m 3/s, respectively. Samples collected immediately after deposition were used to determine the water content and bulk density of the material. Channel scouring, fines enrichment and transported volume increase testify erosion and entrainment of material along the flow channel. Field estimates of the rheological properties based on open channel flow of Bingham fluid indicate a yield strength of 5000±400 Pa and relatively low viscosity (60-326 Pa s), probably due to a high percentage of fines (approx. 30%).

  7. Current Issues in Orbital Debris

    NASA Technical Reports Server (NTRS)

    Johnson, Nicholas L.

    2011-01-01

    During the past two decades, great strides have been made in the international community regarding orbital debris mitigation. The majority of space-faring nations have reached a consensus on an initial set of orbital debris mitigation measures. Implementation of and compliance with the IADC and UN space debris mitigation guidelines should remain a high priority. Improvements of the IADC and UN space debris mitigation guidelines should continue as technical consensus permits. The remediation of the near-Earth space environment will require a significant and long-term undertaking.

  8. MEO Debris Environment Projection Study

    NASA Astrophysics Data System (ADS)

    Jenkin, Alan B.; Sorge, Marlon E.; McVey, John P.; Peterson, Glenn E.; Yoo, Bernard Y.

    2013-08-01

    The recently developed Aerospace Debris Environment Projection Tool was used to project the future debris environment in medium Earth orbit (MEO) over the next 200 years. The entire Earth orbital population was modeled to account for the possibility of cross-coupling between the MEO population and the low Earth orbit (LEO) and geosynchronous populations via objects on highly eccentric orbits that transit through MEO. It was found that a large fraction of the MEO debris originated from collisions in LEO involving satellites and rocket bodies that transit through LEO and MEO. Results showed that world-wide compliance with orbit lifetime reduction will significantly reduce the amount of debris in MEO.

  9. Space Debris Hazard Evaluation

    NASA Technical Reports Server (NTRS)

    Davison, Elmer H.; Winslow, Paul C., Jr.

    1961-01-01

    The hazard to space vehicles from natural space debris has been explored. A survey of the available information pertinent to this problem is presented. The hope is that this presentation gives a coherent picture of the knowledge to date in terms of the topic covered. The conclusion reached is that a definite hazard exists but that it can only be poorly assessed on the basis of present information. The need for direct measurement of this hazard is obvious, and some of the problems involved in making these direct measurements have been explored.

  10. Removal of orbital debris

    NASA Technical Reports Server (NTRS)

    Petro, Andrew J.; Talent, David L.

    1989-01-01

    The several methods presently identified for the reduction of orbital debris populations are broadly classifiable as either preventive or remedial, and fall within distinctive operational regimes. For all particles, (1) in the 250-2000-km altitude band, intelligent sweepers may be used; (2) for large objects, in the 80-250-km altitude band, orbital decay renders removal impractical; (3) for the 250-750-km altitude band, deorbit devices should be used; (4) for 750-2500-km altitude, OMV rendezvous for propulsive deorbit package attachment is foreseeable; and beyond 2500 km, (5) propulsive escape from earth orbit is required.