Rehydration ratio of fluid bed-dried vegetables

Indian Academy of Sciences (India)

Fluid-bed drying of vegetable pieces has been investigated. The vegetables used have been potatoes, parsley roots, celery roots and carrots of various dimensions. Starting water content was: potatoes 78%, parsley roots 85.1%, celery roots 93.6%, and carrots 88.6%. Temperatures of fluidisation have varied from 60° to ...

Fluid bed dryer and Aeropep solidification system

International Nuclear Information System (INIS)

1975-01-01

Performance measurements were made on the model of the Fluidized-bed Calciner developed by Aerojet Liquid Rocket Co. The measurements were made over the period August 11-19, 1975, at the Sacramento location of the calciner. The purpose of the tests was to evaluate the performance of the ALRC Fluidized Bed Concentrator for the processing of simulated waste containing realistic concentrations and chemical forms of radioiodine. (auth)

Time and speed of fruit drying on batch fluid-beds

Indian Academy of Sciences (India)

Drying of particles (pieces) in a fluidized bed affords better quality of end products, especially for better product structure and its shorter reconstitution time. Fluid-bed drying of different fruit particles has been investigated. Starting water content varies from grape berries 81·5% and peach 87·7% to apricot 86·9%.

Enhanced Productivity of Chemical Processes Using Dense Fluidized Beds

Energy Technology Data Exchange (ETDEWEB)

Sibashis Banerjee; Alvin Chen; Rutton Patel; Dale Snider; Ken Williams; Timothy O' Hern; Paul Tortora

2008-02-29

The work detailed in this report addresses Enabling Technologies within Computational Technology by integrating a “breakthrough” particle-fluid computational technology into traditional Process Science and Engineering Technology. The work completed under this DOE project addresses five major development areas 1) gas chemistry in dense fluidized beds 2) thermal cracking of liquid film on solids producing gas products 3) liquid injection in a fluidized bed with particle-to-particle liquid film transport 4) solid-gas chemistry and 5) first level validation of models. Because of the nature of the research using tightly coupled solids and fluid phases with a Lagrangian description of the solids and continuum description of fluid, the work provides ground-breaking advances in reactor prediction capability. This capability has been tested against experimental data where available. The commercial product arising out of this work is called Barracuda and is suitable for a wide (dense-to-dilute) range of industrial scale gas-solid flows with and without reactions. Commercial applications include dense gas-solid beds, gasifiers, riser reactors and cyclones.

Fluidized-bed reactors processes and operating conditions

CERN Document Server

Yates, John G

2016-01-01

The fluidized-bed reactor is the centerpiece of industrial fluidization processes. This book focuses on the design and operation of fluidized beds in many different industrial processes, emphasizing the rationale for choosing fluidized beds for each particular process. The book starts with a brief history of fluidization from its inception in the 1940’s. The authors present both the fluid dynamics of gas-solid fluidized beds and the extensive experimental studies of operating systems and they set them in the context of operating processes that use fluid-bed reactors. Chemical engineering students and postdocs as well as practicing engineers will find great interest in this book.

Batch top-spray fluid bed coating: Scale-up insight using dynamic heat- and mass-transfer modelling

DEFF Research Database (Denmark)

Hede, Peter Dybdahl; Bach, P.; Jensen, Anker Degn

2009-01-01

A mathematical model was developed for batch top-spray fluid bed coating processes based on Ronsse et al. [2007a.b. Combined population balance and thermodynamic modelling of the batch top-spray fluidised bed coating process. Part I-model development and validation. journal of Food Engineering 78......, 296-307; Combined population balance and thermodynamic modelling of the batch top-spray fluidised bed coating process. Part II-model and process analysis. journal of Food Engineering 78, 308-322]. The model is based on one-dimensional discretisation of the fluid bed into a number of well-mixed control......-up principles by comparing simulation results with experimental temperature and humidity data obtained from inorganic salt coating of placebo cores in three pilot fluid bed scales being a 0.5kg small-scale (GEA Aeromatic-Fielder Strea-1), 4kg medium-scale (GEA Niro MP-1) and 24kg large-scale (GEA MP-2...

International evaluation of the programme on fluid bed combustion and gasification

Energy Technology Data Exchange (ETDEWEB)

Kremer, H. [Ruhr Univ., Bochum (Germany); Magnusson, B.F. [Norwegian Univ. of Science and Technology, Trondheim (Norway); Reed, T. [Colorado School of Mines (United States)

1996-12-31

This report on the Swedish National Program on Fluid Bed Combustion and Gasification is part of the on-going evaluation process adopted by the funding organization NUTEK. This agency has invited the undersigned to act as members of an international panel responsible for evaluating the progress made in 9 projects initiated between 1993-1996. The output of this evaluation procedure is given in this report. The main aim of the Fluid Bed Combustion and Gasification Program is to develop industrially relevant knowledge and competence in experimental and computational techniques capable of characterizing the flow, heat transfer, combustion, gasification, ash formation and deposition and emissions in fluid bed gasifiers and combustors. To achieve this aim NUTEK is sponsoring research in a number of universities and encourages close cooperation between universities and industry. In the evaluation of the various sponsored research programs, the evaluation committee has considered the following key points: relevance of research to industrial needs; originality of research; program management; adequacy of resources; degree of collaboration between industry and academia; international standing of research. In this report comments and recommendations are made on individual projects as well as on the programme in general and they express the unanimous view of the panel members

International evaluation of the programme on fluid bed combustion and gasification

Energy Technology Data Exchange (ETDEWEB)

Kremer, H [Ruhr Univ., Bochum (Germany); Magnusson, B F [Norwegian Univ. of Science and Technology, Trondheim (Norway); Reed, T [Colorado School of Mines (United States)

1997-12-31

This report on the Swedish National Program on Fluid Bed Combustion and Gasification is part of the on-going evaluation process adopted by the funding organization NUTEK. This agency has invited the undersigned to act as members of an international panel responsible for evaluating the progress made in 9 projects initiated between 1993-1996. The output of this evaluation procedure is given in this report. The main aim of the Fluid Bed Combustion and Gasification Program is to develop industrially relevant knowledge and competence in experimental and computational techniques capable of characterizing the flow, heat transfer, combustion, gasification, ash formation and deposition and emissions in fluid bed gasifiers and combustors. To achieve this aim NUTEK is sponsoring research in a number of universities and encourages close cooperation between universities and industry. In the evaluation of the various sponsored research programs, the evaluation committee has considered the following key points: relevance of research to industrial needs; originality of research; program management; adequacy of resources; degree of collaboration between industry and academia; international standing of research. In this report comments and recommendations are made on individual projects as well as on the programme in general and they express the unanimous view of the panel members

Fluid-bed combustion

Energy Technology Data Exchange (ETDEWEB)

Hunt, G.; Schoebotham, N.

1981-02-01

In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

Dehydration studies using a novel multichamber microscale fluid bed dryer with in-line near-infrared measurement

DEFF Research Database (Denmark)

Räsänen, Eetu; Rantanen, Jukka; Mannermaa, Jukka-Pekka

2003-01-01

The purpose of this research was to study the effect of two process parameters (temperature and moisture content) on dehydration behavior of different materials using a novel multichamber microscale fluid bed dryer with a process air control unit and in-line near-infrared (NIR) spectroscopy....... The materials studied were disodium hydrogen phosphates with three different levels of hydrate water and wet theophylline granules. Measured process parameters of fluid bed drying were logged, including in-line NIR signals. Off-line analyses consisted of X-ray powder diffraction patterns, Fourier transform NIR...... spectra and moisture contents of studied materials. During fluid bed drying, the stepwise dehydration of materials was observed by the water content difference of inlet and outlet air, the pressure difference over the bed, and the in-line NIR spectroscopy. The off-line analysis confirmed the state...

Data Quality Objectives For Selecting Waste Samples To Test The Fluid Bed Steam Reformer Test

International Nuclear Information System (INIS)

Banning, D.L.

2010-01-01

This document describes the data quality objectives to select archived samples located at the 222-S Laboratory for Fluid Bed Steam Reformer testing. The type, quantity and quality of the data required to select the samples for Fluid Bed Steam Reformer testing are discussed. In order to maximize the efficiency and minimize the time to treat Hanford tank waste in the Waste Treatment and Immobilization Plant, additional treatment processes may be required. One of the potential treatment processes is the fluid bed steam reformer (FBSR). A determination of the adequacy of the FBSR process to treat Hanford tank waste is required. The initial step in determining the adequacy of the FBSR process is to select archived waste samples from the 222-S Laboratory that will be used to test the FBSR process. Analyses of the selected samples will be required to confirm the samples meet the testing criteria.

Why the two-fluid model fails to predict the bed expansion characteristics of Geldart A particles in gas-fluidized beds: A tentative answer

NARCIS (Netherlands)

Wang, J.; van der Hoef, Martin Anton; Kuipers, J.A.M.

2009-01-01

It is well known that two-fluid models (TFMs) can successfully predict the hydrodynamics of Geldart B and D particles. However, up to now, TFM have failed to accurately describe the hydrodynamics of Geldart A particles inside bubbling gas-fluidized beds: Researchers have reported that bed expansions

Why the two-fluid model fails to predict the bed expansion characteristics of Geldart A particles in gas-fluidized beds: A tentative answers

NARCIS (Netherlands)

Wang, J.; Hoef, van der M.A.; Kuipers, J.A.M.

2009-01-01

It is well known that two-fluid models (TFMs) can successfully predict the hydrodynamics of Geldart B and D particles. However, up to now, TFM have failed to accurately describe the hydrodynamics of Geldart A particles inside bubbling gas-fluidized beds: Researchers have reported that bed expansions

Effects of exercise on fluid exchange and body composition in man during 14-day bed rest

Science.gov (United States)

Greenleaf, J. E.; Bernauer, E. M.; Juhos, L. T.; Young, H. L.; Morse, J. T.; Staley, R. W.

1977-01-01

A description is presented of an investigation in which body composition, fluid intake, and fluid and electrolyte losses were measured in seven normal, healthy men during three 2-wk bed-rest periods, separated by two 3-wk recovery periods. During bed rest the subjects remained in the horizontal position continuously. During the dietary control periods, body mass decreased significantly with all three regimens, including no exercise, isometric exercise, and isotonic excercise. During bed rest, body mass was essentially unchanged with no exercise, but decreased significantly with isotonic and isometric exercise. With one exception, there were no statistically significant changes in body density, lean body mass, or body fat content by the end of each of the three bed-rest periods.

Fluid bed dryer and Aeropep solidification system. Amendment 1 to topical report

International Nuclear Information System (INIS)

1975-01-01

Information is presented on interfaces between the aerojet fluid bed dryer and the liquid radwaste system, plant ventilation system, and radioactive solid waste handling system for BWR and PWR type reactors. (U.S.)

Rheology of Active Fluids

Science.gov (United States)

Saintillan, David

2018-01-01

An active fluid denotes a viscous suspension of particles, cells, or macromolecules able to convert chemical energy into mechanical work by generating stresses on the microscale. By virtue of this internal energy conversion, these systems display unusual macroscopic rheological signatures, including a curious transition to an apparent superfluid-like state where internal activity exactly compensates viscous dissipation. These behaviors are unlike those of classical complex fluids and result from the coupling of particle configurations with both externally applied flows and internally generated fluid disturbances. Focusing on the well-studied example of a suspension of microswimmers, this review summarizes recent experiments, models, and simulations in this area and highlights the critical role played by the rheological response of these active materials in a multitude of phenomena, from the enhanced transport of passive suspended objects to the emergence of spontaneous flows and collective motion.

Hydraulic fracturing chemicals and fluids technology

CERN Document Server

Fink, Johannes

2013-01-01

When classifying fracturing fluids and their additives, it is important that production, operation, and completion engineers understand which chemical should be utilized in different well environments. A user's guide to the many chemicals and chemical additives used in hydraulic fracturing operations, Hydraulic Fracturing Chemicals and Fluids Technology provides an easy-to-use manual to create fluid formulations that will meet project-specific needs while protecting the environment and the life of the well. Fink creates a concise and comprehensive reference that enables the engineer to logically select and use the appropriate chemicals on any hydraulic fracturing job. The first book devoted entirely to hydraulic fracturing chemicals, Fink eliminates the guesswork so the engineer can select the best chemicals needed on the job while providing the best protection for the well, workers and environment. Pinpoints the specific compounds used in any given fracturing operation Provides a systematic approach to class...

Fluids in crustal deformation: Fluid flow, fluid-rock interactions, rheology, melting and resources

Science.gov (United States)

Lacombe, Olivier; Rolland, Yann

2016-11-01

Fluids exert a first-order control on the structural, petrological and rheological evolution of the continental crust. Fluids interact with rocks from the earliest stages of sedimentation and diagenesis in basins until these rocks are deformed and/or buried and metamorphosed in orogens, then possibly exhumed. Fluid-rock interactions lead to the evolution of rock physical properties and rock strength. Fractures and faults are preferred pathways for fluids, and in turn physical and chemical interactions between fluid flow and tectonic structures, such as fault zones, strongly influence the mechanical behaviour of the crust at different space and time scales. Fluid (over)pressure is associated with a variety of geological phenomena, such as seismic cycle in various P-T conditions, hydrofracturing (including formation of sub-horizontal, bedding-parallel veins), fault (re)activation or gravitational sliding of rocks, among others. Fluid (over)pressure is a governing factor for the evolution of permeability and porosity of rocks and controls the generation, maturation and migration of economic fluids like hydrocarbons or ore forming hydrothermal fluids, and is therefore a key parameter in reservoir studies and basin modeling. Fluids may also help the crust partially melt, and in turn the resulting melt may dramatically change the rheology of the crust.

Bile salt/phospholipid mixed micelle precursor pellets prepared by fluid-bed coating

Directory of Open Access Journals (Sweden)

Dong F

2013-04-01

Full Text Available Fuxia Dong,1,2 Yunchang Xie,1 Jianping Qi,1 Fuqiang Hu,3 Yi Lu,1 Sanming Li,2 Wei Wu1 1School of Pharmacy, Fudan University, Key Laboratory of Smart Drug Delivery of Ministry of Education and PLA, Shanghai, People’s Republic of China; 2School of Pharmacy, Shenyang Pharmaceutical University, Liaoning, People’s Republic of China; 3School of Pharmacy, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Bile salt/phospholipid mixed micelles (MMs are potent carriers used for oral absorption of drugs that are poorly soluble in water; however, there are many limitations associated with liquid formulations. In the current study, the feasibility of preparing bile salt/phospholipid MM precursor (preMM pellets with high oral bioavailability, using fluid-bed coating technology, was examined. In this study, fenofibrate (FB and sodium deoxycholate (SDC were used as the model drug and the bile salt, respectively. To prepare the MMs and to serve as the micellular carrier, a weight ratio of 4:6 was selected for the sodium deoxycholate/phospholipids based on the ternary phase diagram. Polyethylene glycol (PEG 6000 was selected as the dispersion matrix for precipitation of the MMs onto pellets, since it can enhance the solubilizing ability of the MMs. Coating of the MMs onto the pellets using the fluid-bed coating technology was efficient and the pellets were spherical and intact. MMs could be easily reconstituted from preMM pellets in water. Although they existed in a crystalline state in the preMM pellets, FB could be encapsulated into the reconstituted MMs, and the MMs were redispersed better than solid dispersion pellets (FB:PEG = 1:3 and Lipanthyl®. The redispersibility of the preMM pellets increased with the increase of the FB/PEG/micellar carrier. PreMM pellets with a FB:PEG:micellar carrier ratio of 1:1.5:1.5 showed 284% and 145% bioavailability relative to Lipanthyl® and solid dispersion pellets (FB:PEG = 1:3, respectively. Fluid-bed

Modelling of Devolatilization in Fluidized Bed Combustion

DEFF Research Database (Denmark)

Stenseng, Mette; Lin, Weigang; Johnsson, Jan Erik

1997-01-01

A mathematical model is developed to describe the devolatilization process in a circulating fluidized bed combustor. The model is a combination of two submodels: single particle devolatilization and fluid dynamics. The single particle model includes the influence of both chemical kinetics and hea...

Activation of Alkaline Irrigation Fluids in Endodontics

Directory of Open Access Journals (Sweden)

Laurence J. Walsh

2017-10-01

Full Text Available In conventional endodontic treatment, alkaline solutions of sodium hypochlorite (NaOCl and ethylenediaminetetraacetic acid (EDTA are used in combination to disinfect the root canal system and to eliminate debris and smear layers. An important concept that has emerged over recent years is the use of active physical methods for agitating these fluids to improve their penetration within areas that are not reached by endodontic instruments and to accelerate the chemical actions of these alkaline fluids against planktonic microorganisms, biofilms, soft tissue remnants and smear layers. Ultrasonic agitation and more recently pulsed lasers have emerged as two promising methods for activating endodontic irrigation fluids. Ultrasonic agitation with piezoelectric devices employs a moving tip, while laser agitation uses a stationary tip. Both methods cause cavitation, followed by implosions and shear forces which assist with debridement. Fluid streaming further enhances the activity of the fluids. While agitation enhances performance of irrigants, extrusion of fluids from the root canal during activation is a hazard that must be controlled.

A new fluid distribution system for scale-flexible expanded bed adsorption

DEFF Research Database (Denmark)

Hubbuch, Jürgen; Heebøll-Nielsen, Anders; Hobley, Timothy John

2002-01-01

of axial dispersion was 6.1 x 10(-6) m(2) (.) s(-1) and 29 theoretical plates were measured. When the rotation rate was raised to 10 rpm, the coefficient of axial dispersion increased to 8.08 x 10(-6) m(2 .) s(-1) and the number of theoretical plates decreased to 22.......A new fluid distribution system designed for expanded bed adsorption was introduced and studied in a 150-cm diameter column. Based on fluid application through a rotating distributor, it eradicates the need for perforated plates, meshes, or local mixers. The effect of rotation rate on column...

Contaminated fluid filtration plant using pneumatically renewable granulated material

International Nuclear Information System (INIS)

Lucas, J.-C.; Messirejean, Pierre.

1980-01-01

This invention concerns a plant for the filtration of a contaminated fluid flow using a granulated material capable of absorbing or adsorbing the contaminants. This plant includes a filtration box within which there is at least one appreciably vertical filtering bed filled with the material and crossed by the fluid flow, loading and discharge compartments respectively located at the top and bottom of the box, each in communication with the filtering bed and an air-actuated transfer system for loading and discharging this bed through these compartments. Facilities of this kind are used mainly in the nuclear and chemical engineering industries to rid their waste of radio-iodines, generally constituted by elementary iodine and methyl iodide, or of toxic gases that contaminate them. The granulated material, whose job it is to trap these contaminants by adsorption or absorption, is generally composed of active carbon or zeolites whose utilisation time is limited [fr

Carbon capture from coal fired power plant using pressurized fluid bed technology

Energy Technology Data Exchange (ETDEWEB)

Williams, Dennis; Christensen, Tor

2010-09-15

This presentation will discuss the use of a pressurized fluid bed boiler system and specialized carbon capture system to burn coal and generagte clean electricity. The paper will present the existing boiler and carbon capture technology and present economics, thermal performance and emissions reduction for a 100Mw module.

Packed Bed Reactor Technology for Chemical-Looping Combustion

NARCIS (Netherlands)

Noorman, S.; Sint Annaland, van M.; Kuipers, J.A.M.

2007-01-01

Chemical-looping combustion (CLC) has emerged as an alternative for conventional power production processes to intrinsically integrate power production and CO2 capture. In this work a new reactor concept for CLC is proposed, based on dynamically operated packed bed reactors. With analytical

Flow of power-law fluids in fixed beds of cylinders or spheres

KAUST Repository

Singh, John P.

2012-10-29

An ensemble average of the equations of motion for a Newtonian fluid over particle configurations in a dilute fixed bed of spheres or cylinders yields Brinkman\\'s equations of motion, where the disturbance velocity produced by a test particle is influenced by the Newtonian fluid stress and a body force representing the linear drag on the surrounding particles. We consider a similar analysis for a power-law fluid where the stress τ is related to the rate of strain e by τ = 2m en-1e, where m and n are constants. In this case, the ensemble-averaged momentum equation includes a body force resulting from the nonlinear drag exerted on the surrounding particles, a power-law stress associated with the disturbance velocity of the test particle, and a stress term that is linear with respect to the test particle\\'s disturbance velocity. The latter term results from the interaction of the test particle\\'s velocity disturbance with the random straining motions produced by the neighbouring particles and is important only in shear-thickening fluids where the velocity disturbances of the particles are long-ranged. The solutions to these equations using scaling analyses for dilute beds and numerical simulations using the finite element method are presented. We show that the drag force acting on a particle in a fixed bed can be written as a function of a particle-concentration-dependent length scale at which the fluid velocity disturbance produced by a particle is modified by hydrodynamic interactions with its neighbours. This is also true of the drag on a particle in a periodic array where the length scale is the lattice spacing. The effects of particle interactions on the drag in dilute arrays (periodic or random) of cylinders and spheres in shear-thickening fluids is dramatic, where it arrests the algebraic growth of the disturbance velocity with radial position when n≥ 1 for cylinders and n≥ 2 for spheres. For concentrated random arrays of particles, we adopt an

Operation of Packed-Bed Reactors Studied in Microgravity

Science.gov (United States)

Motil, Brian J.; Balakotaiah, Vemuri

2004-01-01

The operation of a packed bed reactor (PBR) involves gas and liquid flowing simultaneously through a fixed-bed of solid particles. Depending on the application, the particles can be various shapes and sizes but are generally designed to force the two fluid phases through a tortuous route of narrow channels connecting the interstitial space. The PBR is the most common type of reactor in industry because it provides for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. Furthermore, this type of reactor is relatively compact and requires minimal power to operate. This makes it an excellent candidate for unit operations in support of long-duration human space activities.

Interactions among Carbon Dioxide, Heat, and Chemical Lures in Attracting the Bed Bug, Cimex lectularius L. (Hemiptera: Cimicidae

Directory of Open Access Journals (Sweden)

Narinderpal Singh

2012-01-01

Full Text Available Commercial bed bug (Cimex lectularius L. monitors incorporating carbon dioxide (CO2, heat, and chemical lures are being used for detecting bed bugs; however, there are few reported studies on the effectiveness of chemical lures in bed bug monitors and the interactions among chemical lure, CO2, and heat. We screened 12 chemicals for their attraction to bed bugs and evaluated interactions among chemical lures, CO2, and heat. The chemical lure mixture consisting of nonanal, 1-octen-3-ol, spearmint oil, and coriander Egyptian oil was found to be most attractive to bed bugs and significantly increased the trap catches in laboratory bioassays. Adding this chemical lure mixture when CO2 was present increased the trap catches compared with traps baited with CO2 alone, whereas adding heat did not significantly increase trap catches when CO2 was present. Results suggest a combination of chemical lure and CO2 is essential for designing effective bed bug monitors.

Chemical Signatures of and Precursors to Fractures Using Fluid Inclusion Stratigraphy

Energy Technology Data Exchange (ETDEWEB)

Lorie M. Dilley

2011-03-30

Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Open or recently closed fractures would be more susceptible to enhancing the permeability of the system. Identifying dense fracture areas as well as large open fractures from small fracture systems will assist in fracture stimulation site selection. Geothermal systems are constantly generating fractures (Moore, Morrow et al. 1987), and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. These fluid inclusions are faithful records of pore fluid chemistry. Fluid inclusions trapped in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. This report presents the results of the project to determine fracture locations by the chemical signatures from gas analysis of fluid inclusions. With this project we hope to test our assumptions that gas chemistry can distinguish if the fractures are open and bearing production fluids or represent prior active fractures and whether there are chemical signs of open fracture systems in the wall rock above the fracture. Fluid Inclusion Stratigraphy (FIS) is a method developed for the geothermal industry which applies the mass quantification of fluid inclusion gas data from drill cuttings and applying known gas ratios and compositions to determine depth profiles of fluid barriers in a modern geothermal system (Dilley, 2009; Dilley et al., 2005; Norman et al., 2005). Identifying key gas signatures associated with fractures for isolating geothermal fluid production is the latest advancement in the application of FIS to geothermal systems (Dilley and Norman, 2005; Dilley and Norman, 2007). Our hypothesis is that peaks in FIS data are related to location of fractures. Previous work (DOE Grant DE-FG36-06GO16057) has indicated differences in the

Differences in fundamental and functional properties of HPMC co-processed fillers prepared by fluid-bed coating and spray drying.

Science.gov (United States)

Dong, QianQian; Zhou, MiaoMiao; Lin, Xiao; Shen, Lan; Feng, Yi

2018-07-01

This study aimed to develop novel co-processed tablet fillers based on the principle of particle engineering for direct compaction and to compare the characteristics of co-processed products obtained by fluid-bed coating and co-spray drying, respectively. Water-soluble mannitol and water-insoluble calcium carbonate were selected as representative fillers for this study. Hydroxypropyl methylcellulose (HPMC), serving as a surface property modifier, was distributed on the surface of primary filler particles via the two co-processing methods. Both fundamental and functional properties of the products were comparatively investigated. The results showed that functional properties of the fillers, like flowability, compactibility, and drug-loading capacity, were effectively improved by both co-processing methods. However, fluid-bed coating showed greater advantages over co-spray drying in some aspects, which was mainly attributed to the remarkable differences in some fundamental properties of co-processed powders, like particle size, surface topology, and particle structure. For example, the more irregular surface and porous structure induced by fluid-bed coating could contribute to better compaction properties and lower lubricant sensitivity due to the increasing contact area and mechanical interlocking between particles under pressure. More effective surface distribution of HPMC during fluid-bed coating was also a contributor. In addition, such a porous agglomerate structure could also reduce the separation of drug and excipients after mixing, resulting in the improvement in drug loading capacity and tablet uniformity. In summary, fluid-bed coating appears to be more promising for co-processing than spray drying in some aspects, and co-processed excipients produced by it have a great prospect for further investigations and development. Copyright © 2018 Elsevier B.V. All rights reserved.

Thermal/chemical degradation of ceramic cross-flow filter materials

Energy Technology Data Exchange (ETDEWEB)

Alvin, M.A.; Lane, J.E.; Lippert, T.E.

1989-11-01

This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

In situ droplet size and speed determination in a fluid-bed granulator.

Science.gov (United States)

Ehlers, Henrik; Larjo, Jussi; Antikainen, Osmo; Räikkönen, Heikki; Heinämäki, Jyrki; Yliruusi, Jouko

2010-05-31

The droplet size affects the final product in fluid-bed granulation and coating. In the present study, spray characteristics of aqueous granulation liquid (purified water) were determined in situ in a fluid-bed granulator. Droplets were produced by a pneumatic nozzle. Diode laser stroboscopy (DLS) was used for droplet detection and particle tracking velocimetry (PTV) was used for determination of droplet size and speed. Increased atomization pressure decreased the droplet size and the effect was most strongly visible in the 90% size fractile. The droplets seemed to undergo coalescence after which only slight evaporation occurred. Furthermore, the droplets were subjected to a strong turbulence at the event of atomization, after which the turbulence reached a minimum value in the lower halve of the chamber. The turbulence increased as speed and droplet size decreased due to the effects of the fluidizing air. The DLS and PTV system used was found to be a useful and rapid tool in determining spray characteristics and in monitoring and predicting nozzle performance. Copyright (c) 2010 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

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

2012-01-01

Highlights: ► We investigate sulphur during MSW gasification within a fluid bed-plasma process. ► We review the literature on the feed, sulphur and process principles therein. ► The need for research in this area was identified. ► We perform thermodynamic modelling of the fluid bed stage. ► 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 2 S) – Na and K based species in particular. Work is underway to further investigate and validate this.

Fluid-bed methane proposed

Energy Technology Data Exchange (ETDEWEB)

1981-05-01

The first full scale plant for the production of methane from organic waste could be built in the next few years believes M.J. Nyns of the University of Louvain, Belgium, utilizing either expanded bed or fluidised bed systems, with more than one stage, in a continuous flow arrangement. Up to 8.0 m cubed gas/m cubed digester/day could be produced with residence times reduced to 34 hours.

The consequences of granulate heterogeneity towards breakage and attrition upon fluid-bed drying

NARCIS (Netherlands)

Nieuwmeyer, Florentine; Maarschalk, Kees van der Voort; Vromans, Herman

High-shear granulated lactose granulates were dried in it fluid-bed dryer at various conditions. Granules were characterized by water content and size analysis. It is shown that the drying process is very dynamic in terms of growth and breakage phenomena. Granular size heterogeneity, composition and

Endocrine active chemicals, pharmaceuticals, and other chemicals of concern in surface water, wastewater-treatment plant effluent, and bed sediment, and biological characteristics in selected streams, Minnesota-design, methods, and data, 2009

Science.gov (United States)

Lee, Kathy E.; Langer, Susan K.; Barber, Larry B.; Writer, Jeff H.; Ferrey, Mark L.; Schoenfuss, Heiko L.; Furlong, Edward T.; Foreman, William T.; Gray, James L.; ReVello, Rhiannon C.; Martinovic, Dalma; Woodruff, Olivia R.; Keefe, Steffanie H.; Brown, Greg K.; Taylor, Howard E.; Ferrer, Imma; Thurman, E. Michael

2011-01-01

This report presents the study design, environmental data, and quality-assurance data for an integrated chemical and biological study of selected streams or lakes that receive wastewater-treatment plant effluent in Minnesota. This study was a cooperative effort of the U.S. Geological Survey, the Minnesota Pollution Control Agency, St. Cloud State University, the University of St. Thomas, and the University of Colorado. The objective of the study was to identify distribution patterns of endocrine active chemicals, pharmaceuticals, and other organic and inorganic chemicals of concern indicative of wastewater effluent, and to identify biological characteristics of estrogenicity and fish responses in the same streams. The U.S. Geological Survey collected and analyzed water, bed-sediment, and quality-assurance samples, and measured or recorded streamflow once at each sampling location from September through November 2009. Sampling locations included surface water and wastewater-treatment plant effluent. Twenty-five wastewater-treatment plants were selected to include continuous flow and periodic release facilities with differing processing steps (activated sludge or trickling filters) and plant design flows ranging from 0.002 to 10.9 cubic meters per second (0.04 to 251 million gallons per day) throughout Minnesota in varying land-use settings. Water samples were collected from the treated effluent of the 25 wastewater-treatment plants and at one point upstream from and one point downstream from wastewater-treatment plant effluent discharges. Bed-sediment samples also were collected at each of the stream or lake locations. Water samples were analyzed for major ions, nutrients, trace elements, pharmaceuticals, phytoestrogens and pharmaceuticals, alkylphenols and other neutral organic chemicals, carboxylic acids, and steroidal hormones. A subset (25 samples) of the bed-sediment samples were analyzed for carbon, wastewater-indicator chemicals, and steroidal hormones; the

Energetic, ecologic and fluid-dynamic analysis of a fluidized bed gasifier operating with sugar cane bagasse

International Nuclear Information System (INIS)

Diniz Filho, Paulo Tasso; Silveira, Jose Luz; Tuna, Celso Eduardo; Lamas, Wendell de Queiroz

2013-01-01

This work aims to study the thermodynamic, ecological and fluid-dynamic aspects of a circulating fluidized bed gasifier using sugar cane bagasse as biomass, in order to estimate a model of its normal operation. In the initial stage was analysed the composition of biomass selected (sugar cane bagasse) and its lower heating value (LHV) was calculated. The energy balance of the gasifier was done, being the volumetric flow of air, synthesis gas and biomass estimated. Also the power produced by this gasifier was theoretically estimated. Then the circulating fluidized bed gasifier was designed for operation with approximately 100 kg/h of processed biomass. Cross-sectional area of the reactor, feeder size, diameter of the exit zone of the gases and minimum height of the expanded bed were selected. Some bed gasifier hydrodynamic factors were also studied. The minimum fluidization velocity, fluidization terminal velocity, and average fluidizing velocity were calculated, in order to understand the fluid-dynamic behaviour of gasification of this fuel. It was obtained a theoretical model that can support a possible prototype of circulating fluidized bed gasifier biomass. Finally, there were studied the ecological aspects of the gasifier, through an overall methodology. Ecological efficiencies were estimated for two scenarios: first considering the carbon cycle and thereafter disregarding the carbon cycle. In both cases, it can be proved the ecological viability of the project. -- Highlights: • we develop a methodology to size a fluidized bed gasifier. • we validate this methodology comparing to a fixed bed gasifier values. • we aggregate ecological efficiency to this methodology

Experimental and Numerical Research Activity on a Packed Bed TES System

Directory of Open Access Journals (Sweden)

Mario Cascetta

2016-09-01

Full Text Available This paper presents the results of experimental and numerical research activities on a packed bed sensible thermal energy storage (TES system. The TES consists of a cylindrical steel tank filled with small alumina beads and crossed by air used as the heat transfer fluid. Experimental tests were carried out while varying some operating parameters such as the mass flow rate, the inlet–outlet temperature thresholds and the aspect ratio (length over diameter. Numerical simulations were carried out using a one-dimensional model, specifically developed in the Matlab-Simulink environment and a 2D axisymmetric model based on the ANSYS-Fluent platform. Both models are based on a two-equation transient approach to calculate fluid and solid phase temperatures. Thermodynamic properties were considered to be temperature-dependent and, in the Computational Fluid Dynamics (CFD model, variable porosity of the bed in the radial direction, thermal losses and the effective conductivity of the alumina beads were also considered. The simulation results of both models were compared to the experimental ones, showing good agreement. The one-dimensional model has the advantage of predicting the axial temperature distribution with a very low computational cost, but it does not allow calculation of the correct energy stored when the temperature distribution is strongly influenced by the wall. To overcome this problem a 2D CFD model was used in this work.

Successful experience with limestone and other sorbents for combustion of biomass in fluid bed power boilers

Energy Technology Data Exchange (ETDEWEB)

Coe, D.R. [LG& E Power Systems, Inc., Irvine, CA (United States)

1993-12-31

This paper presents the theoretical and practical advantages of utilizing limestone and other sorbents during the combustion of various biomass fuels for the reduction of corrosion and erosion of boiler fireside tubing and refractory. Successful experiences using a small amount of limestone, dolomite, kaolin, or custom blends of aluminum and magnesium compounds in fluid bed boilers fired with biomass fuels will be discussed. Electric power boiler firing experience includes bubbling bed boilers as well as circulating fluid bed boilers in commercial service on biomass fuels. Forest sources of biomass fuels fired include wood chips, brush chips, sawmill waste wood, bark, and hog fuel. Agricultural sources of biomass fuels fired include grape vine prunings, bean straw, almond tree chips, walnut tree chips, and a variety of other agricultural waste fuels. Additionally, some urban sources of wood fuels have been commercially burned with the addition of limestone. Data presented includes qualitative and quantitative analyses of fuel, sorbent, and ash.

Fluid flow and heat transfer investigation of pebble bed reactors using mesh adaptive large-eddy simulation

International Nuclear Information System (INIS)

Pavlidis, D.; Lathouwers, D.

2011-01-01

A computational fluid dynamics model with anisotropic mesh adaptivity is used to investigate coolant flow and heat transfer in pebble bed reactors. A novel method for implicitly incorporating solid boundaries based on multi-fluid flow modelling is adopted. The resulting model is able to resolve and simulate flow and heat transfer in randomly packed beds, regardless of the actual geometry, starting off with arbitrarily coarse meshes. The model is initially evaluated using an orderly stacked square channel of channel-height-to-particle diameter ratio of unity for a range of Reynolds numbers. The model is then applied to the face-centred cubical geometry. Coolant flow and heat transfer patterns are investigated. (author)

Granule size control and targeting in pulsed spray fluid bed granulation.

Science.gov (United States)

Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

2009-07-30

The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

Controlling the Release of Indomethacin from Glass Solutions Layered with a Rate Controlling Membrane Using Fluid-Bed Processing. Part 1: Surface and Cross-Sectional Chemical Analysis.

Science.gov (United States)

Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy

2017-04-03

Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer

Fluid flow and heat transfer investigation of pebble bed reactors using mesh-adaptive LES

International Nuclear Information System (INIS)

Pavlidis, Dimitrios; Lathouwers, Danny

2013-01-01

The very high temperature reactor is one of the designs currently being considered for nuclear power generation. One its variants is the pebble bed reactor in which the coolant passes through complex geometries (pores) at high Reynolds numbers. A computational fluid dynamics model with anisotropic mesh adaptivity is used to investigate coolant flow and heat transfer in such reactors. A novel method for implicitly incorporating solid boundaries based on multi-fluid flow modelling is adopted. The resulting model is able to resolve and simulate flow and heat transfer in randomly packed beds, regardless of the actual geometry, starting off with arbitrarily coarse meshes. The model is initially evaluated using an orderly stacked square channel of channel-height-to-particle diameter ratio of unity for a range of Reynolds numbers. The model is then applied to the face-centred cubical geometry. coolant flow and heat transfer patterns are investigated

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

Science.gov (United States)

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

Science.gov (United States)

Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

In Situ Decommissioning Sensor Network, Meso-Scale Test Bed - Phase 3 Fluid Injection Test Summary Report

International Nuclear Information System (INIS)

Serrato, M. G.

2013-01-01

located at the Florida International University Applied Research Center, Miami, FL (FIU-ARC). A follow-on fluid injection test was developed to detect fluid and ion migration in a cementitious material/grouted test cube using a limited number of existing embedded sensor systems. This In Situ Decommissioning Sensor Network, Meso-Scale Test Bed (ISDSN-MSTB) - Phase 3 Fluid Injection Test Summary Report summarizes the test implementation, acquired and processed data, and results from the activated embedded sensor systems used during the fluid injection test. The ISDSN-MSTB Phase 3 Fluid Injection Test was conducted from August 27 through September 6, 2013 at the FIU-ARC ISDSN-MSTB test cube. The fluid injection test activated a portion of the existing embedded sensor systems in the ISDSN-MSTB test cube: Electrical Resistivity Tomography-Thermocouple Sensor Arrays, Advance Tensiometer Sensors, and Fiber Loop Ringdown Optical Sensors. These embedded sensor systems were activated 15 months after initial placement. All sensor systems were remotely operated and data acquisition was completed through the established Sensor Remote Access System (SRAS) hosted on the DOE D&D Knowledge Management Information Tool (D&D DKM-IT) server. The ISDN Phase 3 Fluid Injection Test successfully demonstrated the feasibility of embedding sensor systems to assess moisture-fluid flow and resulting transport potential for contaminate mobility through a cementitious material/grout monolith. The ISDSN embedded sensor systems activated for the fluid injection test highlighted the robustness of the sensor systems and the importance of configuring systems in-depth (i.e., complementary sensors and measurements) to alleviate data acquisition gaps

In Situ Decommissioning Sensor Network, Meso-Scale Test Bed - Phase 3 Fluid Injection Test Summary Report

Energy Technology Data Exchange (ETDEWEB)

Serrato, M. G.

2013-09-27

located at the Florida International University Applied Research Center, Miami, FL (FIU-ARC). A follow-on fluid injection test was developed to detect fluid and ion migration in a cementitious material/grouted test cube using a limited number of existing embedded sensor systems. This In Situ Decommissioning Sensor Network, Meso-Scale Test Bed (ISDSN-MSTB) - Phase 3 Fluid Injection Test Summary Report summarizes the test implementation, acquired and processed data, and results from the activated embedded sensor systems used during the fluid injection test. The ISDSN-MSTB Phase 3 Fluid Injection Test was conducted from August 27 through September 6, 2013 at the FIU-ARC ISDSN-MSTB test cube. The fluid injection test activated a portion of the existing embedded sensor systems in the ISDSN-MSTB test cube: Electrical Resistivity Tomography-Thermocouple Sensor Arrays, Advance Tensiometer Sensors, and Fiber Loop Ringdown Optical Sensors. These embedded sensor systems were activated 15 months after initial placement. All sensor systems were remotely operated and data acquisition was completed through the established Sensor Remote Access System (SRAS) hosted on the DOE D&D Knowledge Management Information Tool (D&D DKM-IT) server. The ISDN Phase 3 Fluid Injection Test successfully demonstrated the feasibility of embedding sensor systems to assess moisture-fluid flow and resulting transport potential for contaminate mobility through a cementitious material/grout monolith. The ISDSN embedded sensor systems activated for the fluid injection test highlighted the robustness of the sensor systems and the importance of configuring systems in-depth (i.e., complementary sensors and measurements) to alleviate data acquisition gaps.

On a criterion of incipient motion and entrainment into suspension of a particle from cuttings bed in shear flow of non-Newtonian fluid

Science.gov (United States)

Ignatenko, Yaroslav; Bocharov, Oleg; May, Roland

2017-10-01

Solids transport is a major issue in high angle wells. Bed-load forms by sediment while transport and accompanied by intermittent contact with stream-bed by rolling, sliding and bouncing. The study presents the results of a numerical simulation of a laminar steady-state flow around a particle at rest and in free motion in a shear flow of Herschel-Bulkley fluid. The simulation was performed using the OpenFOAM open-source CFD package. A criterion for particle incipient motion and entrainment into suspension from cuttings bed (Shields criteria) based on forces and torques balance is discussed. Deflection of the fluid parameters from the ones of Newtonian fluid leads to decreasing of the drag and lift forces and the hydrodynamic moment. Thus, the critical shear stress (Shields parameter) for the considered non-Newtonian fluid must be greater than the one for a Newtonian fluid.

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

Energy Technology Data Exchange (ETDEWEB)

Soria, José, E-mail: jose.soria@probien.gob.ar [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina); Gauthier, Daniel; Flamant, Gilles [Processes, Materials and Solar Energy Laboratory (PROMES-CNRS, UPR 8521), 7 Four Solaire Street, Odeillo, 66120 Font-Romeu (France); Rodriguez, Rosa [Chemical Engineering Institute, National University of San Juan, 1109 Libertador (O) Avenue, 5400 San Juan (Argentina); Mazza, Germán [Institute for Research and Development in Process Engineering, Biotechnology and Alternative Energies (PROBIEN, CONICET – UNCo), 1400 Buenos Aires St., 8300 Neuquén (Argentina)

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.

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

International Nuclear Information System (INIS)

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

2015-01-01

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

Mass transfer between a fluid and an immersed object in liquid–solid packed and fluidized beds

Directory of Open Access Journals (Sweden)

NEVENKA BOSKOVIC-VRAGOLOVIC

2005-11-01

Full Text Available Themass transfer coefficient between fluid and an immersed sphere in liquid packed and fluidized beds of inert spherical particles have been studied experimentally using a column 40 mm in diameter. The mass transfer data were obtained by studying the transfer of benzoic acid from the immersed sphere to flowing water using the dissolution method. In all runs, the mass transfer rates were determined in the presence of inert glass particles 0.50-2.98 mm in diameter. The influence of different parameters, such as: liquid velocity, particles size and bed voidage, on the mass transfer in packed and fluidized beds is presented. The obtained experimental data for mass transfer in the packed and particulate fluidized bed were correlated by a single correlation, thus confirming the similarity between the two systems.

Fluidized bed pyrolysis of HDPE: A study of the influence of operating variables and the main fluid dynamic parameters on the composition and production of gases

Energy Technology Data Exchange (ETDEWEB)

Martinez, Lidia; Aguado, Alicia; Moral, Alberto [CARTOF Centro Tecnologico, Valladolid (Spain). Environmental Div.; Irusta, Ruben [CARTOF Centro Tecnologico, Valladolid (Spain). Environmental Div.; Valladolid Univ. (Spain). Dept. of Chemical Engineering and Environmental Technology

2011-02-15

In the present work, a preliminary study of the pyrolysis process of high density polyethylene (HDPE) in a fluidized bed is investigated in order to determine the influence between the fluid dynamic properties of the bed reactor and the amount and composition of the gases produced. As is known, fluidized bed technology is a very interesting option to apply in the pyrolysis field due to i) the lack of moving parts in the hot region that facilitates the maintenance of equipment, ii) the high surface area to volume ratio available in the bed, and iii) the high heat transfer coefficient reached which governs the reaction products. But, heat and mass transfer coefficients are strongly affected by the fluid dynamic properties of the bed. During the pyrolysis of HDPE, a fluid dynamic characterization of the bed particles that consist of char-coated sand of HDPE has been carried out. Parameters such as the minimum fluidizing velocity (u{sub mf}), terminal velocity (u{sub t}), bed height (h{sub f}), bed voidage ({epsilon}{sub f}), fraction of the bed occupied by bubbles ({delta}), bubble diameter (d{sub b}), bubble velocity (u{sub b}), the mass transfer coefficients between the bubble and the cloud (K{sub bc}) and between the cloud and the emulsion (K{sub ce}) were determined. Subsequently, the influence of major operating variables and the fluid dynamic parameters on the composition and the gas yield of the pyrolysis of HDPE were studied. (author)

Chemical looping fluidized-bed concentrating solar power system and method

Science.gov (United States)

Ma, Zhiwen

2017-07-11

A concentrated solar power (CSP) plant comprises a receiver configured to contain a chemical substance for a chemical reaction and an array of heliostats. Each heliostat is configured to direct sunlight toward the receiver. The receiver is configured to transfer thermal energy from the sunlight to the chemical substance in a reduction reaction. The CSP plant further comprises a first storage container configured to store solid state particles produced by the reduction reaction and a heat exchanger configured to combine the solid state particles and gas through an oxidation reaction. The heat exchanger is configured to transfer heat produced in the oxidation reaction to a working fluid to heat the working fluid. The CSP plant further comprises a power turbine coupled to the heat exchanger, such that the heated working fluid turns the power turbine, and a generator coupled to and driven by the power turbine to generate electricity.

Supercritical Fluids Processing of Biomass to Chemicals and Fuels

Energy Technology Data Exchange (ETDEWEB)

Olson, Norman K. [Iowa State Univ., Ames, IA (United States)

2011-09-28

The main objective of this project is to develop and/or enhance cost-effective methodologies for converting biomass into a wide variety of chemicals, fuels, and products using supercritical fluids. Supercritical fluids will be used both to perform reactions of biomass to chemicals and products as well as to perform extractions/separations of bio-based chemicals from non-homogeneous mixtures. This work supports the Biomass Program’s Thermochemical Platform Goals. Supercritical fluids are a thermochemical approach to processing biomass that, while aligned with the Biomass Program’s interests in gasification and pyrolysis, offer the potential for more precise and controllable reactions. Indeed, the literature with respect to the use of water as a supercritical fluid frequently refers to “supercritical water gasification” or “supercritical water pyrolysis.”

Fluid bed solids heater. Final technical report

Energy Technology Data Exchange (ETDEWEB)

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.

Chemical-looping combustion in a reverse-flow fixed bed reactor

International Nuclear Information System (INIS)

Han, Lu; Bollas, George M.

2016-01-01

A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

Fluidized-bed calcination of simulated commercial high-level radioactive wastes

International Nuclear Information System (INIS)

Freeby, W.A.

1975-11-01

Work is in progress at the Idaho Chemical Processing Plant to verify process flowsheets for converting simulated commercial high-level liquid wastes to granular solids using the fluidized-bed calcination process. Primary emphasis in the series of runs reported was to define flowsheets for calcining simulated Allied-General Nuclear Services (AGNS) waste and to evaluate product properties significant to calcination, solids storage, or post treatment. Pilot-plant studies using simulated high-level acid wastes representative of those to be produced by Nuclear Fuel Services, Inc. (NFS) are also included. Combined AGNS high-level and intermediate-level waste (0.26 M Na in blend) was successfully calcined when powdered iron was added (to result in a Na/Fe mole ratio of 1.0) to the feed to prevent particle agglomeration due to sodium nitrate. Long-term runs (approximately 100 hours) showed that calcination of the combined waste is practical. Concentrated AGNS waste containing sodium at concentrations less than 0.2 M were calcined successfully; concentrated waste containing 1.13 M Na calcined successfully when powdered iron was added to the feed to suppress sodium nitrate formation. Calcination of dilute AGNS waste by conventional fluid-bed techniques was unsuccessful due to the inability to control bed particle size--both particle size and bed level decreased. Fluid-bed solidification of AGNS dilute waste at conditions in which most of the calcined solids left the calciner vessel with the off-gas was successful. In such a concept, the steady-state composition of the bed material would be approximately 22 wt percent calcined solids deposited on inert particles. Calcination of simulated NFS acid waste indicated that solidification by the fluid-bed process is feasible

Effect of various drying bed on thermodynamic characteristics

Directory of Open Access Journals (Sweden)

Ali Motevali

2017-09-01

Full Text Available In this study thermodynamic parameter and energy consumption in drying of two plant dill and mint in three bed drying including fix, semi fix and fluid with using a hot air drying was investigated. Experimental was conducted in three bed drying including fix, semi fix and fluid and four levels temperature (30, 40, 50 and 60 °C. Maximum energy consumption in dill drying at 40 °C and fluid bed to be 16.41 MJ and minimum energy consumption at 30 °C and fix bed to be 2.77 MJ. Also minimum energy consumption in mint drying at 60 °C and fix bed to be 3.64 MJ and maximum energy consumption at 40 °C and fluid bed to be 28.65 MJ. The highest energy, drying and thermal efficiency for both mint and dill was achieved at 60 °C on the fixed bed, whereas the lowest efficiency was at 40 °C and on the fluidized bed. Also the highest power and specific heat consumption for both mint and dill was achieved at 40 °C on the fluid bed, whereas the lowest efficiency was at 30 °C and on the fluidized bed.

Batch and fixed bed adsorption of levofloxacin on granular activated carbon from date (Phoenix dactylifera L.) stones by KOH chemical activation.

Science.gov (United States)

Darweesh, Teeba M; Ahmed, Muthanna J

2017-03-01

Granular activated carbon (KAC) was prepared from abundant Phoenix dactylifera L. stones by microwave- assisted KOH activation. The characteristics of KAC were tested by pore analyses, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR). The adsorption behavior of levofloxacin (LEV) antibiotic on KAC with surface area of 817m 2 /g and pore volume of 0.638cm 3 /g were analyzed using batch and fixed bed systems. The equilibrium data collected by batch experiments were well fitted with Langmuir compared to Freundlich and Temkin isotherms. The effect of flow rate (0.5-1.5ml/min), bed height (15-25cm), and initial LEV concentration (75-225mg/l) on the behavior of breakthrough curves was explained. The fixed bed analysis showed the better correlation of breakthrough data by both Thomas and Yoon-Nelson models. High LEV adsorption capacity of 100.3mg/g was reported on KAC, thus being an efficient adsorbent for antibiotic pollutants to protect ecological systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Trickle-bed root culture bioreactor design and scale-up: growth, fluid-dynamics, and oxygen mass transfer.

Science.gov (United States)

Ramakrishnan, Divakar; Curtis, Wayne R

2004-10-20

Trickle-bed root culture reactors are shown to achieve tissue concentrations as high as 36 g DW/L (752 g FW/L) at a scale of 14 L. Root growth rate in a 1.6-L reactor configuration with improved operational conditions is shown to be indistinguishable from the laboratory-scale benchmark, the shaker flask (mu=0.33 day(-1)). These results demonstrate that trickle-bed reactor systems can sustain tissue concentrations, growth rates and volumetric biomass productivities substantially higher than other reported bioreactor configurations. Mass transfer and fluid dynamics are characterized in trickle-bed root reactors to identify appropriate operating conditions and scale-up criteria. Root tissue respiration goes through a minimum with increasing liquid flow, which is qualitatively consistent with traditional trickle-bed performance. However, liquid hold-up is much higher than traditional trickle-beds and alternative correlations based on liquid hold-up per unit tissue mass are required to account for large changes in biomass volume fraction. Bioreactor characterization is sufficient to carry out preliminary design calculations that indicate scale-up feasibility to at least 10,000 liters.

Formulating food protein-stabilized indomethacin nanosuspensions into pellets by fluid-bed coating technology: physical characterization, redispersibility, and dissolution.

Science.gov (United States)

He, Wei; Lu, Yi; Qi, Jianping; Chen, Lingyun; Yin, Lifang; Wu, Wei

2013-01-01

Drug nanosuspensions are very promising for enhancing the dissolution and bioavailability of drugs that are poorly soluble in water. However, the poor stability of nanosuspensions, reflected in particle growth, aggregation/agglomeration, and change in crystallinity state greatly limits their applications. Solidification of nanosuspensions is an ideal strategy for addressing this problem. Hence, the present work aimed to convert drug nanosuspensions into pellets using fluid-bed coating technology. Indomethacin nanosuspensions were prepared by the precipitation-ultrasonication method using food proteins (soybean protein isolate, whey protein isolate, β-lactoglobulin) as stabilizers. Dried nanosuspensions were prepared by coating the nanosuspensions onto pellets. The redispersibility, drug dissolution, solid-state forms, and morphology of the dried nanosuspensions were evaluated. The mean particle size for the nanosuspensions stabilized using soybean protein isolate, whey protein isolate, and β-lactoglobulin was 588 nm, 320 nm, and 243 nm, respectively. The nanosuspensions could be successfully layered onto pellets with high coating efficiency. Both the dried nanosuspensions and nanosuspensions in their original amorphous state and not influenced by the fluid-bed coating drying process could be redispersed in water, maintaining their original particle size and size distribution. Both the dried nanosuspensions and the original drug nanosuspensions showed similar dissolution profiles, which were both much faster than that of the raw crystals. Fluid-bed coating technology has potential for use in the solidification of drug nanosuspensions.

Concentration profiles in the wake of a sphere buried in a granular bed through which fluid flows

International Nuclear Information System (INIS)

Guedes de Carvalho, J.R.F.; Delgado, J.M.P.Q.; Alves, M.A.

2005-01-01

The concentration distribution in the wake of a soluble sphere immersed in a granular bed of inerts has been obtained numerically, for transport by both advection and diffusion/dispersion. Fluid flow in the granular bed around the sphere was assumed to follow Darcy's law and, at each point, dispersion of solute was considered in both the cross-stream and stream-wise directions. The elliptic PDE equation, resulting from a differential material balance on the solute, has been solved numerically over a wide range of values of the relevant parameters. (authors)

Concentration profiles in the wake of a sphere buried in a granular bed through which fluid flows

Energy Technology Data Exchange (ETDEWEB)

Guedes de Carvalho, J.R.F.; Delgado, J.M.P.Q.; Alves, M.A. [Porto Univ., Dpet. de Engenharia Quimica, Faculdade de Engenharia (Portugal)

2005-07-01

The concentration distribution in the wake of a soluble sphere immersed in a granular bed of inerts has been obtained numerically, for transport by both advection and diffusion/dispersion. Fluid flow in the granular bed around the sphere was assumed to follow Darcy's law and, at each point, dispersion of solute was considered in both the cross-stream and stream-wise directions. The elliptic PDE equation, resulting from a differential material balance on the solute, has been solved numerically over a wide range of values of the relevant parameters. (authors)

Chemical characteristics of beddings for swine: effects of bedding depths and of addition of inoculums in a pilot-scale.

Science.gov (United States)

Corrêa, E K; Corezzolla, J L; Corrêa, M N; Bianchi, I; Gil-Turnes, C; Lucia, T

2012-11-01

The effect of depths and of addition of inoculums on the chemical content of swine beddings was evaluated. For beddings 0.25m (25D) and 0.50m (50D) deep, three treatments were tested in two repeats with the same beddings: control (no inoculums); T1 (250g of Bacillus cereus var. toyoii at 8.4×10(7)CFU/g); and T2 (250g of a pool of Bacillus sp. at 8.4×10(7)CFU/g) (250g for 25D and 500g for 50D). For 25D, the C:N ratio was lower, but N, K and C contents were greater than for 50D (P0.05). In the second repeat, beddings presented lower C:N ratio and greater N, P and K contents than in the first repeat (P<0.05). Thus, the compost produced after using 25D twice had greater fertilizer value than that of 50D. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stable isotope composition of fluid inclusions preserved in halite derived from Wieliczka and Bochnia beds (southern Poland)

International Nuclear Information System (INIS)

Dulinski, M.; Rozanski, K.; Alexandrowicz, Z.; Chmura, A.

1999-01-01

Halite deposits located in the southern Poland, near Krakow, are famous mostly due to medieval salt mine located in Wieliczka. Contrary to most salt deposits in Europe forming large domes, the halite deposits near Krakow form distinct beds, extending from west to east on the area of ca. 10 km 2 , with several types of salt identified. The deposits were formed in Miocene, ca. 15 mln years ago. Stable isotope composition of fluid inclusions trapped in the halite crystals originating from Wieliczka and Bochnia salt mines was investigated. Two distinct groups of samples were analyzed: (i) samples derived from so-called 'green salt' beds forming extensive horizontal structures, and (ii) large monocrystals of halite collected in crystal caves which form a part of the tourist tract within the Wieliczka Salt Mine. The samples belonging to the first group were heated under vacuum to extract the fluid inclusions, according to the procedure developed in our laboratory and used previously to extract inclusions from speleothem samples. The macro-inclusions present in some monocrystals of halite collected in crystal caves were removed or analysis without any thermal treatment. The concentration of bivalent cations (Ca 2+ , Mg 2- was measured in the bulk material and in fluid inclusions (only second group). The 2 H and 18 O isotope composition of fluid inclusions extracted from halite samples was measured

Effects of process parameters on solid self-microemulsifying particles in a laboratory scale fluid bed.

Science.gov (United States)

Mukherjee, Tusharmouli; Plakogiannis, Fotios M

2012-01-01

The purpose of this study was to select the critical process parameters of the fluid bed processes impacting the quality attribute of a solid self-microemulsifying (SME) system of albendazole (ABZ). A fractional factorial design (2(4-1)) with four parameters (spray rate, inlet air temperature, inlet air flow, and atomization air pressure) was created by MINITAB software. Batches were manufactured in a laboratory top-spray fluid bed at 625-g scale. Loss on drying (LOD) samples were taken throughout each batch to build the entire moisture profiles. All dried granulation were sieved using mesh 20 and analyzed for particle size distribution (PSD), morphology, density, and flow. It was found that as spray rate increased, sauter-mean diameter (D(s)) also increased. The effect of inlet air temperature on the peak moisture which is directly related to the mean particle size was found to be significant. There were two-way interactions between studied process parameters. The main effects of inlet air flow rate and atomization air pressure could not be found as the data were inconclusive. The partial least square (PLS) regression model was found significant (P SME manufacturing process.

Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.

Science.gov (United States)

Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

2013-01-01

Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level.

Effects of the fluid flows on enzymatic chemical oscillations

Science.gov (United States)

Shklyaev, Oleg; Yashin, Victor; Balazs, Anna

2017-11-01

Chemical oscillations are ubiquitous in nature and have a variety of promising applications. Usually, oscillating chemical systems are analyzed within the context of a reaction-diffusion framework. Here, we examine how fluid flows carrying the reactants can be utilized to modulate the negative feedback loops and time delays that promote chemical oscillations. We consider a model where a chemical reaction network involves two species, X and Y, which undergo transformations catalyzed by respective enzymes immobilized at the bottom wall of a fluid-filled microchamber. The reactions with the enzymes provide a negative feedback in the chemically oscillating system. In particular, the first enzyme, localized on the first patch, promotes production of chemical X, while the second enzyme, immobilized on the second patch, promotes production of chemical Y, which inhibits the production of chemical X. The separation distance between the enzyme-coated patches sets the time delay required for the transportation of X and Y. The chemical transport is significantly enhanced if convective fluxes accompany the diffusive ones. Therefore, the parameter region where oscillations are present is modified. The findings provide guidance to designing micro-scale chemical reactors with improved functionalities.

Impact of Poultry Litter Cake, Cleanout, and Bedding following Chemical Amendments on Soil C and N Mineralization

Directory of Open Access Journals (Sweden)

Dexter B. Watts

2012-01-01

Full Text Available Poultry litter is a great alternative N source for crop production. However, recent poultry litter management changes, and increased chemical amendment use may impact its N availability. Thus, research was initiated to evaluate the effect that broiler cake and total cleanout litter amended with chemical additives have on C and N mineralization. A 35-day incubation study was carried out on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults soil common to the USA Appalachian Plateau region. Three poultry litter components (broiler cake, total cleanout, and bedding material from a broiler house were evaluated and compared to a soil control. Chemical amendments lime (CaCO3, gypsum (CaSO4, aluminum sulfate (AlSO4, and ferrous sulfate (FeSO4 were added to the poultry litter components to determine their impact on C and N mineralization. Litter component additions increased soil C mineralization in the order of broiler cake > total cleanout > bedding > soil control. Although a greater concentration of organic C was observed in the bedding, broiler cake mineralized the most C, which can be attributed to differences in the C : N ratio between treatments. Chemical amendment in addition to the manured soil also impacted C mineralization, with AlSO4 generally decreasing mineralization. Nitrogen mineralization was also significantly affected by poultry litter component applications. Broiler cake addition increased N availability followed by total cleanout compared to soil control, while the bedding resulted in net N immobilization. Chemical amendments impacted N mineralization primarily in the broiler cake amended soil where all chemical amendments decreased mineralization compared to the no chemical amendment treatment. This short-term study (35-day incubation indicates that N availability to crops may be different depending on the poultry litter component used for fertilization and chemical amendment use which could

Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel; Simulation de la combustion en boucle chimique d'une charge gazeuse dans un lit fluidise circulant

Energy Technology Data Exchange (ETDEWEB)

Mahalatkar, K.; Kuhlman, J. [West Virginia University, Dept. of Mechanical and Aerospace Engineering, Morgantown, WV, 26506 (United States); Mahalatkar, K. [ANSYS Inc., 3647 Collins Ferry Road Suite A, Morgantown, WV, 26505 (United States); Kuhlman, J.; Huckaby, E.D.; O' Brien, T. [National Energy Technology Laboratory, 3610 Collins Ferry Road, Morgantown, WV, 26507 (United States)

2011-03-15

Numerical studies using Computational Fluid Dynamics (CFD) have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185). There have been extensive experimental studies in Chemical Looping Combustion (CLC), however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particle-particle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. (authors)

Numerical modeling of pyrolysis of sawdust in a packed bed

Energy Technology Data Exchange (ETDEWEB)

Meng, Qingmin; Chen, Xiaoping [Southeast Univ., Nanjing (China). School of Energy and Environment

2013-07-01

An unsteady, one-dimensional mathematical model has been developed to describe the pyrolysis of sawdust in a packed bed. The sawdust bed was pyrolyzed using the hot gas and an electric heater outside the bed as the source of energy. The developed model includes mass, momentum and energy conservations of gas and solid within the bed. The gas flow in the bed is modeled using Darcy's law for fluid through a porous medium. The heat transfer model includes heat conduction inside the bed and convection between the bed and the hot gas. The kinetic model consists of primary pyrolysis reaction. A finite volume fully implicit scheme is employed for solving the heat and mass transfer model equations. A Runge-Kutta fourth order method is used for the chemical kinetics model equations. The model predictions of mass loss history and temperature were validated with published experimental results, showing a good agreement. The effects of inlet temperature on the pyrolysis process have been analyzed with model simulation. A sensitivity analysis using the model suggests that the predictions could be improved by considering the second reaction which could generate volatile flowing in the void.

Corn stalks char from fast pyrolysis as precursor material for preparation of activated carbon in fluidized bed reactor.

Science.gov (United States)

Wang, Zhiqi; Wu, Jingli; He, Tao; Wu, Jinhu

2014-09-01

Corn stalks char from fast pyrolysis was activated by physical and chemical activation process in a fluidized bed reactor. The structure and morphology of the carbons were characterized by N2 adsorption and SEM. Effects of activation time and activation agents on the structure of activation carbon were investigated. The physically activated carbons with CO2 have BET specific surface area up to 880 m(2)/g, and exhibit microporous structure. The chemically activated carbons with H3PO4 have BET specific surface area up to 600 m(2)/g, and exhibit mesoporous structure. The surface morphology shows that physically activated carbons exhibit fibrous like structure in nature with long ridges, resembling parallel lines. Whereas chemically activated carbons have cross-interconnected smooth open pores without the fibrous like structure. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of a visiometric process analyzer for real-time monitoring of bottom spray fluid-bed coating.

Science.gov (United States)

Liew, Celine Valeria; Wang, Li Kun; Wan Sia Heng, Paul

2010-01-01

Particle recirculation within the partition column is a major source of process variability in the bottom spray fluid-bed coating process. However, its locality and complex nature make it hidden from the operator. The aim of this study was to take snapshots of the process by employing a visiometric process analyzer based on high-speed imaging and ensemble correlation particle image velocimetry (PIV) to quantify particle recirculation. High-speed images of particles within the partition column of a bottom spray fluid-bed coater were captured and studied by morphological image processing and ensemble correlation PIV. Particle displacement probability density function (PDF) obtained from ensemble correlation PIV was consistent with validation experiments using an image tracking method. Particle displacement PDF was further resolved into particle velocity magnitude and particle velocity orientation histograms, which gave information about particle recirculation probability, thus quantifying the main source of process variability. Deeper insights into particle coating process were obtained and better control of coat uniformity can thus be achieved with use of the proposed visiometric process analyzer. The concept of visiometric process analyzers was proposed and their potential applications in pharmaceutical processes were further discussed.

Multi-stage circulating fluidized bed syngas cooling

Science.gov (United States)

Liu, Guohai; Vimalchand, Pannalal; Guan, Xiaofeng; Peng, WanWang

2016-10-11

A method and apparatus for cooling hot gas streams in the temperature range 800.degree. C. to 1600.degree. C. using multi-stage circulating fluid bed (CFB) coolers is disclosed. The invention relates to cooling the hot syngas from coal gasifiers in which the hot syngas entrains substances that foul, erode and corrode heat transfer surfaces upon contact in conventional coolers. The hot syngas is cooled by extracting and indirectly transferring heat to heat transfer surfaces with circulating inert solid particles in CFB syngas coolers. The CFB syngas coolers are staged to facilitate generation of steam at multiple conditions and hot boiler feed water that are necessary for power generation in an IGCC process. The multi-stage syngas cooler can include internally circulating fluid bed coolers, externally circulating fluid bed coolers and hybrid coolers that incorporate features of both internally and externally circulating fluid bed coolers. Higher process efficiencies can be realized as the invention can handle hot syngas from various types of gasifiers without the need for a less efficient precooling step.

Active magnetic regenerator method and apparatus

Science.gov (United States)

DeGregoria, Anthony J.; Zimm, Carl B.; Janda, Dennis J.; Lubasz, Richard A.; Jastrab, Alexander G.; Johnson, Joseph W.; Ludeman, Evan M.

1993-01-01

In an active magnetic regenerator apparatus having a regenerator bed of material exhibiting the magnetocaloric effect, flow of heat transfer fluid through the bed is unbalanced, so that more fluid flows through the bed from the hot side of the bed to the cold side than from the cold side to the hot side. The excess heat transfer fluid is diverted back to the hot side of the bed. The diverted fluid may be passed through a heat exchanger to draw heat from a fluid to be cooled. The apparatus may be operated at cryogenic temperatures, and the heat transfer fluid may be helium gas and the fluid to be cooled may be hydrogen gas, which is liquified by the device. The apparatus can be formed in multiple stages to allow a greater span of cooling temperatures than a single stage, and each stage may be comprised of two bed parts. Where two bed parts are employed in each stage, a portion of the fluid passing from the hot side to the cold side of a first bed part which does not have a magnetic field applied thereto is diverted back to the cold side of the other bed part in the stage, where it is passed through to the hot side. The remainder of the fluid from the cold side of the bed part of the first stage is passed to the hot side of the bed part of the second stage.

Chemical and radiolytical characterization of perfluorocarbon fluids used as coolants for LHC experiments : radiolysis effects in perfluorohexane fluids.

CERN Document Server

Ilie, Soran; Teissandier, B; CERN. Geneva. TS Department

2007-01-01

Perfluorohexane fluids, used as coolants within High Energy Physics Detectors in the Large Hadrons Collider (LHC) at CERN, were irradiated using gammas 60Co and characterized using different analytical techniques. The aim of this work was the assessment of radiation induced effects as a function of the chemical nature of these fluids and their impurity content. Were evidenced the radioinduced polymers and acidity, as well as different chemical by-products. Purification tests and measurements were carried out on different irradiated fluid samples to assess the efficiency of such purification treatments in view of their re-use in the HEP detector cooling systems.

Numerical simulation and experimental verification of gas flow through packed beds

International Nuclear Information System (INIS)

Natarajan, S.; Zhang, C.; Briens, C.

2003-01-01

This work is concerned with finding out an effective way of eliminating oxygen from a packed bed of monomer particles. This process finds application in industries involved in the manufacture of Nylon12. In the manufacture of the polymer Nylon12, the polymerization reaction is hindered by the presence of oxygen. Therefore, the main objective of this study is to get rid of the oxygen by injecting nitrogen to displace the oxygen from the voids in-between the monomer particles before they are introduced into the polymerization reactor. This work involves the numerical simulation and experimental verification of the flow in a packed bed. In addition, a parametric study is carried out for the parameters such as the number of injectors, the radial position of injectors, and the position of the injectors along the circumference of the packed bed to find out the best possible combination for effective elimination of the oxygen. Nitrogen does not interact with the monomer particles and hence there is no chemical reaction involved in this process. The nitrogen is introduced into the packed bed at a flow rate which will keep the superficial velocity well below the minimum fluidization velocity of the monomer particles. The packed bed will be modeled using a porous medium approach available in the commercial computational fluid dynamics (CFD) software FLUENT. The fluid flow inside the packed bed will be a multicomponent gas flow through a porous medium. The simulation results are validated by comparing with the experimental results. (author)

The characterization of fluidization behavior using a novel multichamber microscale fluid bed

DEFF Research Database (Denmark)

Räsänen, Eetu; Rantanen, Jukka; Mannermaa, Jukka-Pekka

2004-01-01

In the preformulation stage, there is a special need to determine the process behavior of materials with smaller amounts of samples. The purpose of this study was to assemble a novel automated multichamber microscale fluid bed module with a process air control unit for the characterization...... of fluidization behavior in variable conditions. The results were evaluated on the basis of two common computational methods, the minimum fluidization velocity, and the Geldart classification. The materials studied were different particle sizes of glass beads, microcrystalline cellulose, and silicified......, the utilization of the computational predictions was restricted. The presented setup is a novel approach for studying process behavior with only a few grams of materials....

Chemical Oxygen Demand abatement in sewage using Micro-Aeration Enhanced Ecological Floating Bed

Science.gov (United States)

Shi, Hongle; Zhou, Gaofeng; Liu, Yiqing; Tan, Jiancong; Fu, Yongsheng

2018-02-01

The traditional ecological floating bed combined with micro-aeration system and artificial medium was developed for the removal of contaminants and remediation of surface water. This micro-aeration enhanced ecological floating bed (MAEEFB) consisted of aeration unit, microbial processing unit and aquatic plant unit. Batch experiments were conducted in different operating conditions on the removal of chemical oxygen demand (COD) in the sewage using MAEEFB. The removal rate of COD by MAEEFB, enhanced ecological floating bed (EEFB) and traditional ecological floating bed (TEFB) in the same reaction conditions was 59.2%, 56.9% and 30.6%, respectively, indicating that the combination of micro-aeration system and artificial medium could enhance the removal efficiency of COD in TEFB. In MAEEFB, the aeration intensity should be designed reasonablely considering both treatment efficiency and operation cost. Only increasing the specific surface area of the packing cannot effectively improve the purification efficiency of water. Factors like packing material, ability of intercepting organics and complicated extent of microorganisms attaching on the packing should also be considered.

Numerical calculation of wall-to-bed heat transfer coefficients in gas-fluidized beds

NARCIS (Netherlands)

Kuipers, J.A.M.; Prins, W.; van Swaaij, W.P.M.

1992-01-01

A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the

Validation of a two-fluid model used for the simulation of dense fluidized beds; Validation d`un modele a deux fluides applique a la simulation des lits fluidises denses

Energy Technology Data Exchange (ETDEWEB)

Boelle, A.

1997-02-17

A two-fluid model applied to the simulation of gas-solid dense fluidized beds is validated on micro scale and on macro scale. Phase coupling is carried out in the momentum and energy transport equation of both phases. The modeling is built on the kinetic theory of granular media in which the gas action has been taken into account in order to get correct expressions of transport coefficients. A description of hydrodynamic interactions between particles in high Stokes number flow is also incorporated in the model. The micro scale validation uses Lagrangian numerical simulations viewed as numerical experiments. The first validation case refers to a gas particle simple shear flow. It allows to validate the competition between two dissipation mechanisms: drag and particle collisions. The second validation case is concerted with sedimenting particles in high Stokes number flow. It allows to validate our approach of hydrodynamic interactions. This last case had led us to develop an original Lagrangian simulation with a two-way coupling between the fluid and the particles. The macro scale validation uses the results of Eulerian simulations of dense fluidized bed. Bed height, particles circulation and spontaneous created bubbles characteristics are studied and compared to experimental measurement, both looking at physical and numerical parameters. (author) 159 refs.

Climbing ability of teneral and sclerotized adult bed bugs and assessment of adhesive properties of the exoskeletal fluid using atomic force microscopy.

Directory of Open Access Journals (Sweden)

Kevin R Hinson

Full Text Available We observed that teneral adults (72 h, and sclerotized group 2 (S2 bed bugs (n = 30, height climbed = 2.64 cm at >72 h post molt. When heights from all climbing events were summed, teneral bed bugs (650.8 cm climbed differed significantly (P< 0.01 from recently sclerotized (82 cm climbed and sclerotized (group 1 = 104.6 cm climbed, group 2 = 107.8 cm climbed bed bugs. These findings suggested that the external surface of teneral bed bug exoskeletons possess an adhesive property. Using atomic force microscopy (AFM, we found that adhesion force of an exoskeletal (presumably molting fluid decreased almost five-fold from 88 to 17 nN within an hour of molting. Our findings may have implications for laboratory safety and the effectiveness of bed bug traps, barriers, and biomimetic-based adhesives.

Carbon coated (carbonous) catalyst in ebullated bed reactor for production of oxygenated chemicals from syngas/CO2

International Nuclear Information System (INIS)

Peizheng Zhou

2002-01-01

This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R and D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO 2 efficiently and economically. Exothermic chemical reactions benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. The carbon-coated extrudates prepared using these procedures had sufficient attrition resistance and surface area for use in ebullated bed operation. The low cost of carbon coating makes the carbon-coated catalysts highly competitive in the market of catalyst extrudates

Chemical changes associated with zeolitization of the tuffaceous beds of Calico Hills at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Broxton, D.E.

1992-01-01

The chemistry of the tuffaceous beds of Calico Hills was examined in samples collected over a 100 2 km area south of the Timber Mountain-Oasis Valley caldera complex to determine regional geochemical patterns during zeolitization. Samples of 58 vitric and zeolitic tuffs were analyzed for 48 elements by a combination of x-ray fluorescence, atomic absorption spectrophotometry, and neutron activation analysis. Major and trace element concentrations for zeolitic tuffs vary significantly from those for vitric tuffs. Complex, geographically-controlled patterns of elemental enrichment and depletion in the zeolitic tuffs are found for Na, K, Ca, Mg, U, Rb, Sr, Ba and Cs. Vitric and zeolitic tuffs generally have the same SiO 2 contents on an anhydrous basis, but minor net silica gain or loss has occurred in some samples. Zeolitic tuffs from the northern part of the study area, adjacent to the caldera complex, are notably K-rich and Na- and U-poor compared to zeolitic tuffs to the south. The compositions of the K-rich zeolitic tuffs are similar to those found in other areas of the western US where volcanic rocks are affected by potassium metasomatism. Alteration of vitric tuffs took place in an open chemical system and geographic control of major element compositions probably reflects regional variations in groundwater chemistry during alteration. The K-rich zeolitic tuffs in the northern part of the study area were probably altered by hydrothermal fluids whereas tuffs further south were altered by lower-temperature groundwaters

Active chiral fluids.

Science.gov (United States)

Fürthauer, S; Strempel, M; Grill, S W; Jülicher, F

2012-09-01

Active processes in biological systems often exhibit chiral asymmetries. Examples are the chirality of cytoskeletal filaments which interact with motor proteins, the chirality of the beat of cilia and flagella as well as the helical trajectories of many biological microswimmers. Here, we derive constitutive material equations for active fluids which account for the effects of active chiral processes. We identify active contributions to the antisymmetric part of the stress as well as active angular momentum fluxes. We discuss four types of elementary chiral motors and their effects on a surrounding fluid. We show that large-scale chiral flows can result from the collective behavior of such motors even in cases where isolated motors do not create a hydrodynamic far field.

Industrial Scale Synthesis of Carbon Nanotubes Via Fluidized Bed Chemical Vapor Deposition: A Senior Design Project

Science.gov (United States)

Smith, York R.; Fuchs, Alan; Meyyappan, M.

2010-01-01

Senior year chemical engineering students designed a process to produce 10 000 tonnes per annum of single wall carbon nanotubes (SWNT) and also conducted bench-top experiments to synthesize SWNTs via fluidized bed chemical vapor deposition techniques. This was an excellent pedagogical experience because it related to the type of real world design…

A Three-Dimensional Numerical Study of Gas-Particle Flow and Chemical Reactions in Circulating Fluidised Bed Reactors

DEFF Research Database (Denmark)

Hansen, Kim Granly

Three-dimensional Computational Fluid Dynamics (CFD) simulations of Circulating Fluidized Beds (CFB's) have been performed. The computations are performed using a 3D multiphase computational fluid dynamics code with an Eulerian description of both gas and particle phases. The turbulent motion...... implemented in the CFD code FLOTRACS-MP-3D. The decomposition reaction is studied in a 3D representation of a 0.254 m i.d. riser, which has been studied experimentally by Ouyang et al. (1993). Comparison between measured and simulated time-averaged ozone concentration at different elevations in the riser...

Understanding and modeling retention of mammalian cells in fluidized bed centrifuges.

Science.gov (United States)

Kelly, William; Rubin, Jonathan; Scully, Jennifer; Kamaraju, Hari; Wnukowski, Piotr; Bhatia, Ravinder

2016-11-01

Within the last decade, fully disposable centrifuge technologies, fluidized-bed centrifuges (FBC), have been introduced to the biologics industry. The FBC has found a niche in cell therapy where it is used to collect, concentrate, and then wash mammalian cell product while continuously discarding centrate. The goal of this research was to determine optimum FBC conditions for recovery of live cells, and to develop a mathematical model that can assist with process scaleup. Cell losses can occur during bed formation via flow channels within the bed. Experimental results with the kSep400 centrifuge indicate that, for a given volume processed: the bed height (a bed compactness indicator) is affected by RPM and flowrate, and dead cells are selectively removed during operation. To explain these results, two modeling approaches were used: (i) equating the centrifugal and inertial forces on the cells (i.e., a force balance model or FBM) and (ii) a two-phase computational fluid dynamics (CFD) model to predict liquid flow patterns and cell retention in the bowl. Both models predicted bed height vs. time reasonably well, though the CFD model proved more accurate. The flow patterns predicted by CFD indicate a Coriolis-driven flow that enhances uniformity of cells in the bed and may lead to cell losses in the outflow over time. The CFD-predicted loss of viable cells and selective removal of the dead cells generally agreed with experimental trends, but did over-predict dead cell loss by up to 3-fold for some of the conditions. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1520-1530, 2016. © 2016 American Institute of Chemical Engineers.

On the influence of infiltration of radioactive beds by flushing fluid on γ-ray logging results obtained from uranium deposit No. 387

International Nuclear Information System (INIS)

Ren Bingxiang; Zhang Yuechun; Ai Shuyi.

1985-01-01

A large number of field logging data obtained during the course of exploration on uranium deposit No. 387 show when the radioactive beds are encountered by drill holes and the drilling continues the γ-ray intensity decreases. It is considered that the escape of emanation does not considerably influence the logging results. Therefore, based upon the experiment of immerseing ores in fluid and geological and hydrogeological data of the deposit, the hypotheses that the γ-ray intensity in drill hole is closely related with the infiltration of flushing fluid is suggested. The ore bodies are strictly controlled by faults. Most of the uranium and thorium are absorbed by pelitic-carbonaceous cements or fill the porous spaces in structural breccia and cataclasite. They are easy to dissolve in water. Moreover, the ore-bearing structures are the unique water aquifers which is under pressure. As the level of flushing fluid is higher than the pressure head so it continuously pours into the ore-bearing beds, resulting in the infiltration of U and Ra. Consequently, the radioactivity detected is low

Coefficient of solid-gas heat transfer in particle fixed bed; Coeficiente de transferencia de calor gas-solido em leito fixo de particulas

Energy Technology Data Exchange (ETDEWEB)

Fernandes Filho, Francisco

1991-03-01

The work presents a study on heat transfer between gas and solid phases for fixed beds in the absence of mass transfer and chemical reactions. Mathematical models presented in the literature were analyzed concerning to the assumptions made on axial dispersion in the fluid phase and interparticle thermal conductivity. Heat transfer coefficients and their dependency on flow conditions, particles and packed bed characteristics were experimentally determined through the solution of the previous mathematical models. Pressure drop behaviour for the packed beds used for the heat transfer study was also included. (author) 32 refs., 12 figs.

Chemical kinetics and transport processes in supercritical fluid extraction of coal. Final report, August 10, 1990--December 30, 1992

Energy Technology Data Exchange (ETDEWEB)

McCoy, B.J.; Smith, J.M.; Wang, M.; Zhang, C.J.

1993-02-01

The overall objective of this project was to study the supercritical fluid extraction of hydrocarbons from coal. Beyond the practical concern of deriving products from coal, the research has provided insights into the structure, properties, and reactivities of coal. Information on engineering fundamentals of coal thermolysis and extraction, including physical and chemical processes, is presented in this final report. To accomplish the goals of the project we developed continuous-flow experiments for fixed-bed samples of coal that allow two types of analysis of the extract: continuous spectrophotometric absorbance measurements of the lumped concentration of extract, and chromatographic determinations of molecular-weight distributions as a function of time. Thermolysis of coal yields a complex mixture of many extract products whose molecular-weight distribution (MWD) varies with time for continuous-flow, semibatch experiments. The flow reactor with a differential, fixed bed of coal particles contacted by supercritical t-butanol was employed to provide dynamic MWD data by means of HPLC gel permeation chromatography of the extract. The experimental results, time-dependent MWDs of extract molecules, were interpreted by a novel mathematical model based on continuous-mixture kinetics for thermal cleavage of chemical bonds in the coal network. The parameters for the MWDs of extractable groups in the coal and the rate constants for one- and two-fragment reaction are determined from the experimental data. The significant effect of temperature on the kinetics of the extraction was explained in terms of one- and two-fragment reactions in the coal.

An integrated fluid-chemical model toward modeling the formation of intra-luminal thrombus in abdominal aortic aneurysms.

Science.gov (United States)

Biasetti, Jacopo; Spazzini, Pier Giorgio; Swedenborg, Jesper; Gasser, T Christian

2012-01-01

Abdominal Aortic Aneurysms (AAAs) are frequently characterized by the presence of an Intra-Luminal Thrombus (ILT) known to influence their evolution biochemically and biomechanically. The ILT progression mechanism is still unclear and little is known regarding the impact of the chemical species transported by blood flow on this mechanism. Chemical agonists and antagonists of platelets activation, aggregation, and adhesion and the proteins involved in the coagulation cascade (CC) may play an important role in ILT development. Starting from this assumption, the evolution of chemical species involved in the CC, their relation to coherent vortical structures (VSs) and their possible effect on ILT evolution have been studied. To this end a fluid-chemical model that simulates the CC through a series of convection-diffusion-reaction (CDR) equations has been developed. The model involves plasma-phase and surface-bound enzymes and zymogens, and includes both plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonian incompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinical observations showing that the thickest ILT is usually seen in the distal AAA region. The proposed model, due to its ability to couple the fluid and chemical domains, provides an integrated mechanochemical picture that potentially could help unveil mechanisms of ILT formation and development.

Elemental mercury vapor capture by powdered activated carbon in a fluidized bed reactor

Energy Technology Data Exchange (ETDEWEB)

Fabrizio Scala; Riccardo Chirone; Amedeo Lancia [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy)

2011-06-15

A bubbling fluidized bed of inert material was used to increase the activated carbon residence time in the reaction zone and to improve its performance for mercury vapor capture. Elemental mercury capture experiments were conducted at 100{sup o}C in a purposely designed 65 mm ID lab-scale pyrex reactor, that could be operated both in the fluidized bed and in the entrained bed configurations. Commercial powdered activated carbon was pneumatically injected in the reactor and mercury concentration at the outlet was monitored continuously. Experiments were carried out at different inert particle sizes, bed masses, fluidization velocities and carbon feed rates. Experimental results showed that the presence of a bubbling fluidized bed led to an increase of the mercury capture efficiency and, in turn, of the activated carbon utilization. This was explained by the enhanced activated carbon loading and gas-solid contact time that establishes in the reaction zone, because of the large surface area available for activated carbon adhesion/deposition in the fluidized bed. Transient mercury concentration profiles at the bed outlet during the runs were used to discriminate between the controlling phenomena in the process. Experimental data have been analyzed in the light of a phenomenological framework that takes into account the presence of both free and adhered carbon in the reactor as well as mercury saturation of the adsorbent. 14 refs., 7 figs.

Breakage and drying behaviour of granules in a continuous fluid bed dryer: Influence of process parameters and wet granule transfer.

Science.gov (United States)

De Leersnyder, F; Vanhoorne, V; Bekaert, H; Vercruysse, J; Ghijs, M; Bostijn, N; Verstraeten, M; Cappuyns, P; Van Assche, I; Vander Heyden, Y; Ziemons, E; Remon, J P; Nopens, I; Vervaet, C; De Beer, T

2018-03-30

Although twin screw granulation has already been widely studied in recent years, only few studies addressed the subsequent continuous drying which is required after wet granulation and still suffers from a lack of detailed understanding. The latter is important for optimisation and control and, hence, a cost-effective practical implementation. Therefore, the aim of the current study is to increase understanding of the drying kinetics and the breakage and attrition phenomena during fluid bed drying after continuous twin screw granulation. Experiments were performed on a continuous manufacturing line consisting of a twin-screw granulator, a six-segmented fluid bed dryer, a mill, a lubricant blender and a tablet press. Granulation parameters were fixed in order to only examine the effect of drying parameters (filling time, drying time, air flow, drying air temperature) on the size distribution and moisture content of granules (both of the entire granulate and of size fractions). The wet granules were transferred either gravimetrically or pneumatically from the granulator exit to the fluid bed dryer. After a certain drying time, the moisture content reached an equilibrium. This drying time was found to depend on the applied airflow, drying air temperature and filling time. The moisture content of the granules decreased with an increasing drying time, airflow and drying temperature. Although smaller granules dried faster, the multimodal particle size distribution of the granules did not compromise uniform drying of the granules when the target moisture content was achieved. Extensive breakage of granules was observed during drying. Especially wet granules were prone to breakage and attrition during pneumatic transport, either in the wet transfer line or in the dry transfer line. Breakage and attrition of granules during transport and drying should be anticipated early on during process and formulation development by performing integrated experiments on the granulator

Fluids in porous media. IV. Quench effect on chemical potential.

Science.gov (United States)

Qiao, C Z; Zhao, S L; Liu, H L; Dong, W

2017-06-21

It appears to be a common sense to measure the crowdedness of a fluid system by the densities of the species constituting it. In the present work, we show that this ceases to be valid for confined fluids under some conditions. A quite thorough investigation is made for a hard sphere (HS) fluid adsorbed in a hard sphere matrix (a quench-annealed system) and its corresponding equilibrium binary mixture. When fluid particles are larger than matrix particles, the quench-annealed system can appear much more crowded than its corresponding equilibrium binary mixture, i.e., having a much higher fluid chemical potential, even when the density of each species is strictly the same in both systems, respectively. We believe that the insight gained from this study should be useful for the design of functionalized porous materials.

Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

Science.gov (United States)

Marquis, G. A.; Roy, A. G.

2012-02-01

This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

Potential fluid mechanic pathways of platelet activation.

Science.gov (United States)

Shadden, Shawn C; Hendabadi, Sahar

2013-06-01

Platelet activation is a precursor for blood clotting, which plays leading roles in many vascular complications and causes of death. Platelets can be activated by chemical or mechanical stimuli. Mechanically, platelet activation has been shown to be a function of elevated shear stress and exposure time. These contributions can be combined by considering the cumulative stress or strain on a platelet as it is transported. Here, we develop a framework for computing a hemodynamic-based activation potential that is derived from a Lagrangian integral of strain rate magnitude. We demonstrate that such a measure is generally maximized along, and near to, distinguished material surfaces in the flow. The connections between activation potential and these structures are illustrated through stenotic flow computations. We uncover two distinct structures that may explain observed thrombus formation at the apex and downstream of stenoses. More broadly, these findings suggest fundamental relationships may exist between potential fluid mechanic pathways for mechanical platelet activation and the mechanisms governing their transport.

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor.

Science.gov (United States)

Lapa, N; Barbosa, R; Lopes, M H; Mendes, B; Abelha, P; Boavida, D; Gulyurtlu, I; Oliveira, J Santos

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub-products of such type

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Lapa, N. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)]. E-mail: ncsn@fct.unl.pt; Barbosa, R. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Lopes, M.H. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Mendes, B. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Abelha, P. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Gulyurtlu, I. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Santos Oliveira, J. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

International Nuclear Information System (INIS)

Lapa, N.; Barbosa, R.; Lopes, M.H.; Mendes, B.; Abelha, P.; Gulyurtlu, I.; Santos Oliveira, J.

2007-01-01

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Scaling of permeabilities and friction factors of homogeneously expanding gas-solids fluidized beds: Geldart’s A powders and magnetically stabilized beds

Directory of Open Access Journals (Sweden)

Hristov Jordan Y.

2006-01-01

Full Text Available The concept of a variable friction factor of fluid-driven de form able powder beds undergoing fluidization is discussed. The special problem discussed addresses the friction factor and bed permeability relationships of Geldart’s A powders and magnetically stabilized beds in axial fields. Governing equations and scaling relation ships are developed through three approaches (1 Minimization of the pressure drop with respect to the fluid velocity employing the Darcy-Forchheimer equation together with the Richardson-Zaki scaling law, (2 Minimization of the pres sure drop across an equivalent-channel replacing the actual packed beds by a straight pipe with bed-equivalent obstacle of a simple geometry, and (3 Entropy minimization method applied in cases of the Darcy-Forchheimer equation and the equivalent-channel model. Bed-to-surface heat transfer coefficients are commented in the context of the porosity/length scale relationships developed. Both the pressure drop curves developments and phase diagram de signs are illustrated by applications of the intersection of asymptotes technique to beds exhibiting certain degree of cohesion.

Influência da imobilização de biomassa e do tamanho da partícula na fluidodinâmica de um reator anaeróbio de leito fluidizado = The influence of immobilized biomass and particle size on the fluid dynamics of an anaerobic fluidized bed reactor

Directory of Open Access Journals (Sweden)

Flavio Bentes Freire

2008-01-01

Full Text Available O estudo da fluidodinâmica é muito comum em diversas áreas relacionadas com a engenharia química, tais como nos processos de secagem e nos reatores químicos. Entretanto, em reatores biológicos empregados no tratamento de águas residuárias, esses aspectos ainda necessitam de investigações mais aprofundadas. Deste modo, é fundamental avaliar a influência da presença do biofilme no comportamento fluidodinâmico do reator, por meio de importantes parâmetros como, por exemplo, a velocidade de mínima fluidização, a expansão, a porosidade do leito e a velocidade terminal da partícula. O objetivo deste trabalho foi realizar uma investigação da fluidodinâmica de um reator anaeróbio de leito fluidizado, tratando uma água residuária sintética preparada a partir da solução utilizada para determinação de DBO, tendo o carvão ativado como meio suportepara a imobilização de biomassa. Especificamente, no trabalho, verificou-se que a biomassa imobilizada aumentou a densidade das partículas e alterou os principais parâmetros fluidodinâmicos avaliados.Fluid dynamic analysis is an important branch of several chemical engineering related areas, such as drying processes and chemical reactors. However, aspects concerning fluid dynamics in wastewater treatment bioreactors still require further investigation, as they highly influence process efficiency. Therefore, it is essential to evaluate the influence of biofilm on the reactor fluid dynamicbehavior, through the analysis of a few important parameters, such as minimum fluidization velocity, bed expansion and porosity, and particle terminal velocity. The main objective of the present work was to investigate the fluid dynamics of an anaerobic fluidized bed reactor, having activated carbon particles as support media for biomass immobilization. Reactor performance was tested using synthetic residual water, which was prepared using the solution employed in BOD determination. The results

Thermal Analysis of Fluidized Bed and Fixed Bed Latent Heat Thermal Storage System

Science.gov (United States)

Beemkumar, N.; Karthikeyan, A.; Shiva Keshava Reddy, Kota; Rajesh, Kona; Anderson, A.

2017-05-01

Thermal energy storage technology is essential because its stores available energy at low cost. Objective of the work is to store the thermal energy in a most efficient method. This work is deal with thermal analysis of fluidized bed and fixed bed latent heat thermal storage (LHTS) system with different encapsulation materials (aluminium, brass and copper). D-Mannitol has been used as phase change material (PCM). Encapsulation material which is in orbicular shape with 4 inch diameter and 2 mm thickness orbicular shaped product is used. Therminol-66 is used as a heat transfer fluid (HTF). Arrangement of encapsulation material is done in two ways namely fluidized bed and fixed bed thermal storage system. Comparison was made between the performance of fixed bed and fluidized bed with different encapsulation material. It is observed that from the economical point of view aluminium in fluidized bed LHTS System has highest efficiency than copper and brass. The thermal energy storage system can be analyzed with fixed bed by varying mass flow rate of oil paves a way to find effective heat energy transfer.

Hydrodynamics of circulating and bubbling fluidized beds

International Nuclear Information System (INIS)

Gidaspow, D.P.; Tsuo, Y.P.; Ding, J.

1991-01-01

This paper reports that a review of modeling of the hydrodynamics of fluidization of bubbling beds showed that inviscid two-fluid models were able to predict a great deal of the behavior of bubbling beds because the dominant mechanism of energy dissipation is the drag between the particles and the fluid. The formation, the growth and the bursting of bubbles were predicted. Predicted wall-to-bed heat transfer coefficients and velocity profiles of jets agreed with measurements. Time average porosity distributions agreed with measurements done using gamma-ray densitometers without the use of any adjustable parameters. However, inviscid models could not correctly predict rates of erosion around tubes immersed into fluidized beds. To correctly model such behavior, granular stresses involving solids viscosity were added into the computer model. This viscosity arises due to random collision of particles. Several models fro this viscosity were investigated and the results compared to measurements of solids distributions in two-dimensional beds and to particle velocities reported in the literature. While in the case of bubbling beds the solids viscosity plays the role of a correction, modeling of a circulating fluidized bed (CFB) without a viscosity is not possible. Recent experimental data obtained at IIT and at IGT show that in CFB the solids viscous dissipation is responsible for as much as half of the pressure drop. From such measurement, solids viscosities were computed. These were used in the two fluid hydrodynamic model, to predict radial solids distributions and solids velocities which matched the experimental distributions. Most important, the model predicted cluster formation and transient internal circulation which is responsible for the favorable characteristics of CFBs, such as good wall-to-bed heat transfer. Video tape movies of computations compared favorably with high speed movies of the experiments

Model of rough bed for numerical simulation of saltation

Czech Academy of Sciences Publication Activity Database

Kharlamova, Irina; Vlasák, Pavel

2015-01-01

Roč. 19, č. 3 (2015), s. 366-385 ISSN 1964-8189 R&D Projects: GA ČR GA103/09/1718; GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : saltation * bed load transport * rough bed * armoured bed * bed roughness Subject RIV: BK - Fluid Dynamics Impact factor: 0.636, year: 2015

Acceleration of coupled granular flow and fluid flow simulations in pebble bed energy systems

Energy Technology Data Exchange (ETDEWEB)

Li, Yanheng, E-mail: liy19@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States); Ji, Wei, E-mail: jiw2@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States)

2013-05-15

Highlights: ► Fast simulation of coupled pebble flow and coolant flow in PBR systems is studied. ► Dimension reduction based on axisymmetric geometry shows significant speedup. ► Relaxation of coupling frequency is investigated and an optimal range is determined. ► A total of 80% efficiency increase is achieved by the two fast strategies. ► Fast strategies can be applied to simulating other general fluidized bed systems. -- Abstract: Fast and accurate approaches to simulating the coupled particle flow and fluid flow are of importance to the analysis of large particle-fluid systems. This is especially needed when one tries to simulate pebble flow and coolant flow in Pebble Bed Reactor (PBR) energy systems on a routine basis. As one of the Generation IV designs, the PBR design is a promising nuclear energy system with high fuel performance and inherent safety. A typical PBR core can be modeled as a particle-fluid system with strong interactions among pebbles, coolants and reactor walls. In previous works, the coupled Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) approach has been investigated and applied to modeling PBR systems. However, the DEM-CFD approach is computationally expensive due to large amounts of pebbles in PBR systems. This greatly restricts the PBR analysis for the real time prediction and inclusion of more physics. In this work, based on the symmetry of the PBR geometry and the slow motion characteristics of the pebble flow, two acceleration strategies are proposed. First, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without loss of accuracy. Pebble flow is simulated by a full 3D DEM, while the coolant flow field is calculated with a 2D CFD simulation by averaging variables along the annular direction in the cylindrical and annular geometries. Second, based on the slow motion of pebble flow, the impact of the coupling frequency on the computation accuracy and efficiency is

Acceleration of coupled granular flow and fluid flow simulations in pebble bed energy systems

International Nuclear Information System (INIS)

Li, Yanheng; Ji, Wei

2013-01-01

Highlights: ► Fast simulation of coupled pebble flow and coolant flow in PBR systems is studied. ► Dimension reduction based on axisymmetric geometry shows significant speedup. ► Relaxation of coupling frequency is investigated and an optimal range is determined. ► A total of 80% efficiency increase is achieved by the two fast strategies. ► Fast strategies can be applied to simulating other general fluidized bed systems. -- Abstract: Fast and accurate approaches to simulating the coupled particle flow and fluid flow are of importance to the analysis of large particle-fluid systems. This is especially needed when one tries to simulate pebble flow and coolant flow in Pebble Bed Reactor (PBR) energy systems on a routine basis. As one of the Generation IV designs, the PBR design is a promising nuclear energy system with high fuel performance and inherent safety. A typical PBR core can be modeled as a particle-fluid system with strong interactions among pebbles, coolants and reactor walls. In previous works, the coupled Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) approach has been investigated and applied to modeling PBR systems. However, the DEM-CFD approach is computationally expensive due to large amounts of pebbles in PBR systems. This greatly restricts the PBR analysis for the real time prediction and inclusion of more physics. In this work, based on the symmetry of the PBR geometry and the slow motion characteristics of the pebble flow, two acceleration strategies are proposed. First, a simplified 3D-DEM/2D-CFD approach is proposed to speed up the DEM-CFD simulation without loss of accuracy. Pebble flow is simulated by a full 3D DEM, while the coolant flow field is calculated with a 2D CFD simulation by averaging variables along the annular direction in the cylindrical and annular geometries. Second, based on the slow motion of pebble flow, the impact of the coupling frequency on the computation accuracy and efficiency is

Chemical looping reforming in packed-bed reactors : modelling, experimental validation and large-scale reactor design

NARCIS (Netherlands)

Spallina, V.; Marinello, B.; Gallucci, F.; Romano, M.C.; van Sint Annaland, M.

This paper addresses the experimental demonstration and model validation of chemical looping reforming in dynamically operated packed-bed reactors for the production of H2 or CH3OH with integrated CO2 capture. This process is a combination of auto-thermal and steam methane reforming and is carried

Induced venous pooling and cardiorespiratory responses to exercise after bed rest

Science.gov (United States)

Convertino, V. A.; Sandler, H.; Webb, P.; Annis, J. F.

1982-01-01

Venous pooling induced by a specially constructed garment is investigated as a possible means for reversing the reduction in maximal oxygen uptake regularly observed following bed rest. Experiments involved a 15-day period of bed rest during which four healthy male subjects, while remaining recumbent in bed, received daily 210-min venous pooling treatments from a reverse gradient garment supplying counterpressure to the torso. Results of exercise testing indicate that while maximal oxygen uptake endurance time and plasma volume were reduced and maximal heart rate increased after bed rest in the control group, those parameters remained essentially unchanged for the group undergoing venous pooling treatment. Results demonstrate the importance of fluid shifts and venous pooling within the cardiovascular system in addition to physical activity to the maintenance of cardiovascular conditioning.

Computational Fluid Dynamics Simulations of Gas-Phase Radial Dispersion in Fixed Beds with Wall Effects

Directory of Open Access Journals (Sweden)

Anthony G. Dixon

2017-10-01

Full Text Available The effective medium approach to radial fixed bed dispersion models, in which radial dispersion of mass is superimposed on axial plug flow, is based on a constant effective dispersion coefficient, DT. For packed beds of a small tube-to-particle diameter ratio (N, the experimentally-observed decrease in this parameter near the tube wall is accounted for by a lumped resistance located at the tube wall, the wall mass transfer coefficient km. This work presents validated computational fluid dynamics (CFD simulations to obtain detailed radial velocity and concentration profiles for eight different computer-generated packed tubes of spheres in the range 5.04 ≤ N ≤ 9.3 and over a range of flow rates 87 ≤ Re ≤ 870 where Re is based on superficial velocity and the particle diameter dp. Initial runs with pure air gave axial velocity profiles vz(r averaged over the length of the packing. Then, simulations with the tube wall coated with methane yielded radial concentration profiles. A model with only DT could not describe the radial concentration profiles. The two-parameter model with DT and km agreed better with the bed-center concentration profiles, but not with the sharp decreases in concentration close to the tube wall. A three-parameter model based on classical two-layer mixing length theory, with a wall-function for the decrease in transverse radial convective transport in the near-wall region, showed greatly improved ability to reproduce the near-wall concentration profiles.

Fabrication of thin-wall, freestanding inertial confinement fusion targets by chemical vapor deposition

International Nuclear Information System (INIS)

Carroll, D.W.; McCreary, W.J.

1982-01-01

To meet the requirements for plasma physics experiments in the inertial confinement fusion (ICF) program, chemical vapor deposition (CVD) in fluid beds was used to fabricate freestanding tungsten spheres and cylinders with wall thicknesses less than 5.0 μm. Molybdenum and molybdenum alloy (TZM) mandrels of the desired geometry were suspended in a carrier bed of dense microspheres contained in an induction-heated fluid-bed reactor. The mandrels were free to float randomly through the bed, and using the reaction WF 6 +3H 2 →/sub /KW +6HF, very fine-grained tungsten was deposited onto the surface at a rate and in a grain size determined by temperature, gas flow rate, system pressure, and duration of the reaction. After coating, a portion of each mandrel was exposed by hole drilling or grinding. The mandrel was then removed by acid leaching, leaving a freestanding tungsten shape. Experimental procedures, mandrel preparation, and results obtained are discussed

Combining microwave resonance technology to multivariate data analysis as a novel PAT tool to improve process understanding in fluid bed granulation.

Science.gov (United States)

Lourenço, Vera; Herdling, Thorsten; Reich, Gabriele; Menezes, José C; Lochmann, Dirk

2011-08-01

A set of 192 fluid bed granulation batches at industrial scale were in-line monitored using microwave resonance technology (MRT) to determine moisture, temperature and density of the granules. Multivariate data analysis techniques such as multiway partial least squares (PLS), multiway principal component analysis (PCA) and multivariate batch control charts were applied onto collected batch data sets. The combination of all these techniques, along with off-line particle size measurements, led to significantly increased process understanding. A seasonality effect could be put into evidence that impacted further processing through its influence on the final granule size. Moreover, it was demonstrated by means of a PLS that a relation between the particle size and the MRT measurements can be quantitatively defined, highlighting a potential ability of the MRT sensor to predict information about the final granule size. This study has contributed to improve a fluid bed granulation process, and the process knowledge obtained shows that the product quality can be built in process design, following Quality by Design (QbD) and Process Analytical Technology (PAT) principles. Copyright © 2011. Published by Elsevier B.V.

Toxic, antimicrobial and hemagglutinating activities of the purple fluid of the sea hare Aplysia dactylomela Rang, 1828

Directory of Open Access Journals (Sweden)

Melo V.M.M.

1998-01-01

Full Text Available The antimicrobial, hemagglutinating and toxic activities of the purple fluid of the sea hare Aplysia dactylomela are described. Intact or dialyzed purple fluid inhibited the growth of species of Gram-positive and Gram-negative bacteria and the action was not bactericidal but bacteriostatic. The active factor or factors were heat labile and sensitive to extreme pH values. The fluid preferentially agglutinated rabbit erythrocytes and, to a lesser extent, human blood cells, and this activity was inhibited by the glycoprotein fetuin, a fact suggesting the presence of a lectin. The fluid was also toxic to brine shrimp nauplii (LD50 141.25 µg protein/ml and to mice injected intraperitoneally (LD50 201.8 ± 8.6 mg protein/kg, in a dose-dependent fashion. These toxic activities were abolished when the fluid was heated. Taken together, the data suggest that the activities of the purple fluid are due primarily to substance(s of a protein nature which may be involved in the chemical defense mechanism of this sea hare.

Tunable 'optical activity' in electrorheological fluids

International Nuclear Information System (INIS)

Zhao, Q.; Zhao, X.P.

2005-01-01

The 'optical activity' of adjustable periodic structure material (SiO 2 and pentaerythrital electrorheological (ER) fluids) is firstly investigated using two kinds of setup. It is found that the rotation angles can be tuned by the external electric field and weight concentrations, and the sign of the rotation angle is negative, so, the used ER fluids are defined as the left-handed optically active substances under the application of electric field. The laser diffraction patterns are also observed in the ER fluids, which indicates the formation of alignment. It is thought that the symmetry breaking of structure induced by applied electric field is the origin of the 'optical activity' in the ER fluids. The electrically tunable 'optical activity' will find innovative applications in displays, optical devices and other fields

Two-compartmental population balance modeling of a pulsed spray fluidized bed granulation based on computational fluid dynamics (CFD) analysis.

Science.gov (United States)

Liu, Huolong; Li, Mingzhong

2014-11-20

In this work a two-compartmental population balance model (TCPBM) was proposed to model a pulsed top-spray fluidized bed granulation. The proposed TCPBM considered the spatially heterogeneous granulation mechanisms of the granule growth by dividing the granulator into two perfectly mixed zones of the wetting compartment and drying compartment, in which the aggregation mechanism was assumed in the wetting compartment and the breakage mechanism was considered in the drying compartment. The sizes of the wetting and drying compartments were constant in the TCPBM, in which 30% of the bed was the wetting compartment and 70% of the bed was the drying compartment. The exchange rate of particles between the wetting and drying compartments was determined by the details of the flow properties and distribution of particles predicted by the computational fluid dynamics (CFD) simulation. The experimental validation has shown that the proposed TCPBM can predict evolution of the granule size and distribution within the granulator under different binder spray operating conditions accurately. Copyright © 2014 Elsevier B.V. All rights reserved.

Real-time imaging as an emerging process analytical technology tool for monitoring of fluid bed coating process.

Science.gov (United States)

Naidu, Venkata Ramana; Deshpande, Rucha S; Syed, Moinuddin R; Wakte, Pravin S

2018-07-01

A direct imaging system (Eyecon TM ) was used as a Process Analytical Technology (PAT) tool to monitor fluid bed coating process. Eyecon TM generated real-time onscreen images, particle size and shape information of two identically manufactured laboratory-scale batches. Eyecon TM has accuracy of measuring the particle size increase of ±1 μm on particles in the size range of 50-3000 μm. Eyecon TM captured data every 2 s during the entire process. The moving average of D90 particle size values recorded by Eyecon TM were calculated for every 30 min to calculate the radial coating thickness of coated particles. After the completion of coating process, the radial coating thickness was found to be 11.3 and 9.11 μm, with a standard deviation of ±0.68 and 1.8 μm for Batch 1 and Batch 2, respectively. The coating thickness was also correlated with percent weight build-up by gel permeation chromatography (GPC) and dissolution. GPC indicated weight build-up of 10.6% and 9.27% for Batch 1 and Batch 2, respectively. In conclusion, weight build-up of 10% can also be correlated with 10 ± 2 μm increase in the coating thickness of pellets, indicating the potential applicability of real-time imaging as an endpoint determination tool for fluid bed coating process.

Flow of a Bingham fluid in a porous bed under the action of a magnetic field: Application to magneto-hemorheology

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J.C. Misra

2017-06-01

Full Text Available The study deals with an investigation of the flow of a Bingham plastic fluid in a porous bed under the action of an external magnetic field. Porosity of the bed has been described by considering Brinkman model. Both steady and pulsatile motion of this non-Newtonian fluid have been analysed. The governing equations are solved numerically by developing a suitable finite difference scheme. As an application of the theory in the field of magneto-hemorheology, the said physical variables have been computed by considering the values of the involved parameters for blood flow in a pathological state, when the system is under the action of an external magnetic field. The pathological state corresponds to a situation, where the lumen of an arterial segment has turned into a porous structure due to formation of blood clots. Numerical estimates are obtained for the velocity profile and volumetric flow rate of blood, as well as for the shear stress, in the case of blood flow in a diseased artery, both the velocity and volumetric flow rate diminish, as the strength of the external magnetic field is enhanced. The study further shows that blood velocity is maximum in the plug (core region. It decreases monotonically as the particles of blood travel towards the wall. The study also bears the potential of providing numerical estimates for many industrial fluids that follow Bingham plastic model, when the values of different parameters are chosen appropriately.

Chemical and thermal evolution of diagenetic fluids and the genesis of U and Cu ore in and adjacent to the Paradox Basin with emphasis on the Lisbon Valley and Temple Mountain areas, Utah and Colorado

International Nuclear Information System (INIS)

Morrison, S.J.

1986-01-01

Strata-of the central Colorado Plateau of southeastern Utah and southwestern Colorado hot Cu(+/-Ag) ore in salt anticline related faults, and stratiform sandstone-type uranium deposits. The goals of this study were to develop, evaluate, and interpret a geochemical data base from a restricted stratigraphic interval, and to develop models of the chemical and thermal evolution of the interaction of rock framework with pore fluids. Fluid inclusions, mineral chemistry, and C/O stable isotopes in calcite gangue associated with vein-type copper ore at Lisbon Valley suggest mixing of two solutions caused precipitation of the ore. Regularly interstratified chlorite/smectite (corrensite) coats grains in marine and eolian sandstones of the Permian Cutler Formation in the Lisbon Valley area. Local hydrothermal fluids rising along the Lisbon fault apparently permeated the Cutler red-bed section and precipitated the clay minerals. Detailed petrographic studies and fluid inclusion data from calcite cements in the Moss Back Member, support theories of syndiagenetic mobilization of humic compounds, uranium fixation and cementation at Lisbon Valley. The Temple Mountain area hosts uranium ore bodies that are unique among sandstone-type uranium deposits in structural setting, mineralogy, exotic elements, and the occurrence of asphaltite in the ores. This study suggests that warm fluids (70 0 C) have migrated along ring fractures bounding the collapse structure as evidenced by fluid inclusions trapped in authigenic dolomite in the basal Triassic Wingate Sandstone. K/Ar dates using alunite indicate that fluid migration was active as late as 13 my. Modeling suggests that dolomite at the Wingate/Chinle contact precipitated as two fluids mixed

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

KAUST Repository

Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.

2013-01-01

Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two

Analysis of the chemical components of hydatid fluid from Echinococcus granulosus

Directory of Open Access Journals (Sweden)

Li Juyi

2013-10-01

Full Text Available Introduction The aim of this study was to explore the environment of Echinococcus granulosus (E. granulosus protoscolices and their relationship with their host. Methods Proteins from the hydatid-cyst fluid (HCF from E. granulosus were identified by proteomics. An inductively coupled plasma atomic emission spectrometer (ICP-AES was used to determine the elements, an automatic biochemical analyzer was used to detect the types and levels of biochemical indices, and an automatic amino acid analyzer was used to detect the types and levels of amino acids in the E. granulosus HCF. Results I Approximately 30 protein spots and 21 peptide mass fingerprints (PMF were acquired in the two-dimensional gel electrophoresis (2-DE pattern of hydatid fluid; II We detected 10 chemical elements in the cyst fluid, including sodium, potassium, calcium, magnesium, copper, and zinc; III We measured 19 biochemical metabolites in the cyst fluid, and the amount of most of these metabolites was lower than that in normal human serum; IV We detected 17 free amino acids and measured some of these, including alanine, glycine, and valine. Conclusions We identified and measured many chemical components of the cyst fluid, providing a theoretical basis for developing new drugs to prevent and treat hydatid disease by inhibiting or blocking nutrition, metabolism, and other functions of the pathogen.

Gravity Drainage of Activated Sludge on Reed Beds

DEFF Research Database (Denmark)

Christensen, Morten Lykkegaard; Dominiak, Dominik Marek; Keiding, Kristian

and operation of reed beds and the efficiencies are often lower than predicted. One reason is that the sludge quality varies from plant to plant and even within plants from time to time. No good method exists for measuring the sludge quality with respect to drainage characteristics. A new experimental method...... has therefore been developed to measure relevant quality parameters: specific cake resistance, settling velocity and cake compressibility. It has been found that activated sludge form highly compressible cake even at the low compressive pressures obtained during drainage. Numerical simulation shows......Activated sludge is a by-product from waste water treatment plants, and the water content in the sludge is high (> 90%). Among several methods to remove the water, sludge drying reed beds are often used to dewater the sludge by drainage. There is, however, no well-defined criterion for design...

Partial chemical equilibrium in fluid dynamics

International Nuclear Information System (INIS)

Ramshaw, J.D.

1980-01-01

An analysis is given for the flow of a multicomponent fluid in which an arbitrary number of chemical reactions may occur, some of which are in equilibrium while the others proceed kinetically. The primitive equations describing this situation are inconvenient to use because the progress rates omega-dot/sub s/ for the equilibrium reactions are determined implicitly by the associated equilibrium constraint conditions. Two alternative equivalent equation systems that are more pleasant to deal with are derived. In the first system, the omega-dot/sub s/ are eliminated by replacing the transport equations for the chemical species involved in the equilibrium reactions with transport equations for the basic components of which these species are composed. The second system retains the usual species transport equations, but eliminates the nonlinear algebraic equilibrium constraint conditions by deriving an explicit expression for the omega-dot/sub s/. Both systems are specialized to the case of an ideal gas mixture. Considerations involved in solving these equation systems numerically are discussed briefly

Thermal-chemical-mechanical feedback during fluid-rock interactions: Implications for chemical transport and scales of equilibria in the crust

International Nuclear Information System (INIS)

Dutrow, Barbara

2008-01-01

Our research evaluates the hypothesis that feedback amongst thermal-chemical-mechanical processes operative in fluid-rock systems alters the fluid flow dynamics of the system which, in turn, affects chemical transport and temporal and spatial scales of equilibria, thus impacting the resultant mineral textural development of rocks. Our methods include computational experimentation and detailed analyses of fluid-infiltrated rocks from well-characterized terranes. This work focuses on metamorphic rocks and hydrothermal systems where minerals and their textures are utilized to evaluate pressure (P), temperature (T), and time (t) paths in the evolution of mountain belts and ore deposits, and to interpret tectonic events and the timing of these events. Our work on coupled processes also extends to other areas where subsurface flow and transport in porous media have consequences such as oil and gas movement, geothermal system development, transport of contaminants, nuclear waste disposal, and other systems rich in fluid-rock reactions. Fluid-rock systems are widespread in the geologic record. Correctly deciphering the products resulting from such systems is important to interpreting a number of geologic phenomena. These systems are characterized by complex interactions involving time-dependent, non-linear processes in heterogeneous materials. While many of these interactions have been studied in isolation, they are more appropriately analyzed in the context of a system with feedback. When one process impacts another process, time and space scales as well as the overall outcome of the interaction can be dramatically altered. Our goals to test this hypothesis are: to develop and incorporate algorithms into our 3D heat and mass transport code to allow the effects of feedback to be investigated numerically, to analyze fluid infiltrated rocks from a variety of terranes at differing P-T conditions, to identify subtle features of the infiltration of fluids and/or feedback, and

Circulating fluidized bed hydrodynamics experiments for the multiphase fluid dynamics research consortium (MFDRC).

Energy Technology Data Exchange (ETDEWEB)

Oelfke, John Barry; Torczynski, John Robert; O' Hern, Timothy John; Tortora, Paul Richard; Bhusarapu, Satish (; ); Trujillo, Steven Mathew

2006-08-01

An experimental program was conducted to study the multiphase gas-solid flow in a pilot-scale circulating fluidized bed (CFB). This report describes the CFB experimental facility assembled for this program, the diagnostics developed and/or applied to make measurements in the riser section of the CFB, and the data acquired for several different flow conditions. Primary data acquired included pressures around the flow loop and solids loadings at selected locations in the riser. Tomographic techniques using gamma radiation and electrical capacitance were used to determine radial profiles of solids volume fraction in the riser, and axial profiles of the integrated solids volume fraction were produced. Computer Aided Radioactive Particle Tracking was used to measure solids velocities, fluxes, and residence time distributions. In addition, a series of computational fluid dynamics simulations was performed using the commercial code Arenaflow{trademark}.

The constitutive distributed parameter model of multicomponent chemical processes in gas, fluid and solid phase

International Nuclear Information System (INIS)

Niemiec, W.

1985-01-01

In the literature of distributed parameter modelling of real processes is not considered the class of multicomponent chemical processes in gas, fluid and solid phase. The aim of paper is constitutive distributed parameter physicochemical model, constructed on kinetics and phenomenal analysis of multicomponent chemical processes in gas, fluid and solid phase. The mass, energy and momentum aspects of these multicomponent chemical reactions and adequate phenomena are utilized in balance operations, by conditions of: constitutive invariance for continuous media with space and time memories, reciprocity principle for isotropic and anisotropic nonhomogeneous media with space and time memories, application of definitions of following derivative and equation of continuity, to the construction of systems of partial differential constitutive state equations, in the following derivative forms for gas, fluid and solid phase. Couched in this way all physicochemical conditions of multicomponent chemical processes in gas, fluid and solid phase are new form of constitutive distributed parameter model for automatics and its systems of equations are new form of systems of partial differential constitutive state equations in sense of phenomenal distributed parameter control

Debris bed cooling following an HCDA in a fast reactor. Final report

International Nuclear Information System (INIS)

Abdel-Khalik, S.I.

1983-01-01

Natural convection within simulated core debris beds has been experimentally and theoretically investigated. The effect of heating method on bed behavior has been found to be important. For directly-heated beds, variations of the downward and upward power fraction and Nusselt numbers with bed loading, power density, particle size, overlying fluid layer height and top surface boundary condition have been determined. Generalized correlations for the upward and downward Nusselt numbers as functions of the internal Rayleigh number have been obtained. Particle tracing techniques have been used to visualize the flow patterns within the bed and overlying fluid layer. The temperature distributions within the bed and overlying fluid layer have also been measured. The experimental data have been compared with COMMIX-lA predictions. Poor agreement has been obtained for both the integral quantities, i.e. downward and upward power fractions and Nusselt numbers, as well as the steady state velocity and temperature distributions. The code does not correctly predict either the magnitude or even the trend of the data

Analysis of the vertical penetration of a heated fluid layer in a solid, miscible bed

International Nuclear Information System (INIS)

Eck, G.

1982-03-01

The present study investigates the mass and heat transfer for the vertical penetration of a heated fluid layer in a solid, miscible bed using water-salt solutions (ZnBr 2 , NaBr) and polyethylenglycol 1500 (PEG) as simulation materials. The time depending spatial distribution of the molten material (PEG) has been measured for the first time with conductivity probes. The dependence of the downward heat flux on the density ratio rho*, i.e. the density of the fluid / the density of the molten solid, has been investigated with two different methods of heating, planar heating with a heat exchanger in a defined initial distance to the PEG-surface and electrolytical volume heating with a defined and timely constant power input. For 1 2 two layers have been observed in the fluid. This phenomenon is caused among other things by an anomality of the mixture density of the system salt solution-PEG. This process affects the downward heat flux so strongly, that it is impossible to transfer the results of such a system in this region of rho* to another system, for example to a corecatcher. The discrepancies between the measured heat fluxes and heat transfer coefficients of this study and that of other authors can be explained by the different construction of the planar heater, or by different boundary conditions in the case of volume heating. (orig.) [de

Treatment of chemical-pharmaceutical wastewater in packed bed anaerobic reactors

Energy Technology Data Exchange (ETDEWEB)

Nacheva, P.M.; Pena-Loera, B.; Moralez-Guzman, F. [Mexican Institute for Water Technology, Jiutepec (Mexico)

2006-07-01

Biological degradation in packed bed anaerobic mesophilic reactors with five different support materials was studied for the treatment of chemical-pharmaceutical wastewater with high COD (23-31 g/L), which contains toxic organic compounds. Experimental up-flow bio-filters were operated at different organic loads for a two-year period. Removals of 80-98% were obtained in the reactors with sand, anthracite and black tezontle, but at relatively low organic loads, less than 3.6 kg m{sup -3} d{sup -1}. The reactor with granular activated carbon (GAC) had a better performance; efficiencies higher than 95% were obtained at loads up to 17kg m{sup -3} d{sup -1} and higher than 80% with loads up to 26 kg m{sup -3} d{sup -1}. Second in performance was the reactor with red tezontle which allows COD removals higher than 80% with loads up to 6 kg m{sup -3} d{sup -1}. The use of GAC as support material allows greater biodegradation rates than the rest of the materials and it makes the process more resistant to organic load increases, inhibition effects and toxicity. Methanogenic activity was inhibited at loads higher than 21.9 kg m{sup -3} d{sup -1} in the GAC-reactor and at loads higher than 3.6 kg m{sup -3} d{sup -1} in the rest of the reactors. At loads lower than the previously mentioned, high methane production yield was obtained, 0.32-0.35 m{sup 33}CH4/kg CODremoved.

Thermal and mechanical behaviour of oxygen carrier materials for chemical looping combustion in a packed bed reactor

International Nuclear Information System (INIS)

Jacobs, M.; Van Noyen, J.; Larring, Y.; Mccann, M.; Pishahang, M.; Amini, S.; Ortiz, M.; Galluci, F.; Sint-Annaland, M.V.; Tournigant, D.; Louradour, E.; Snijkers, F.

2015-01-01

Highlights: • Ilmenite-based oxygen carriers were developed for packed-bed chemical looping. • Addition of Mn_2O_3 increased mechanical strength and microstructure of the carriers. • Oxygen carriers were able to withstand creep and thermal cycling up to 1200 °C. • Ilmenite-based granules are a promising shape for packed-bed reactor conditions. - Abstract: Chemical looping combustion (CLC) is a promising carbon capture technology where cyclic reduction and oxidation of a metallic oxide, which acts as a solid oxygen carrier, takes place. With this system, direct contact between air and fuel can be avoided, and so, a concentrated CO_2 stream is generated after condensation of the water in the exit gas stream. An interesting reactor system for CLC is a packed bed reactor as it can have a higher efficiency compared to a fluidized bed concept, but it requires other types of oxygen carrier particles. The particles must be larger to avoid a large pressure drop in the reactor and they must be mechanically strong to withstand the severe reactor conditions. Therefore, oxygen carriers in the shape of granules and based on the mineral ilmenite were subjected to thermal cycling and creep tests. The mechanical strength of the granules before and after testing was investigated by crush tests. In addition, the microstructure of these oxygen particles was studied to understand the relationship between the physical properties and the mechanical performance. It was found that the granules are a promising shape for a packed bed reactor as no severe degradation in strength was noticed upon thermal cycling and creep testing. Especially, the addition of Mn_2O_3 to the ilmenite, which leads to the formation of an iron–manganese oxide, seems to results in stronger granules than the other ilmenite-based granules.

The Bulgarian coal and the fluid bed technology

International Nuclear Information System (INIS)

Konstantinov, M.; Georgiev, J.; Lebedov, K.; Petrov, N.

2000-01-01

Because of low-quality of the most of Bulgarian coal and more rigorous ecological restrictions for decreasing of greenhouse gases the fluidized bed technology is the most appropriate combustion technology. A study with a pilot plant aiming to establish the values of technological parameters in view to maintain stable process of fluidized bed combustion at the specific burning characteristics of the Bulgarian coal was carried out. Coal of different quality and particle size production of 'Marbas' LTD mines were used. Series of experiments with batches of strictly determined content were carried out at minimal, average and maximal load. The technological factors as: layer's aerodynamics, layer's height, fuel's quantity and quantity of inert material were changed at each batch. The ecological factors were optimized considering coal's quality, plant's parameters, limestone's dosing and layer's aerodynamics. A regressive model for optimization of technological and ecological factors was created. An average coefficient of performance was achieved, resp. 82.27 % at combustion of coal from mines 'Maritsa-West' and 90 % from mine 'Lev'. A coefficient of sulfur oxides' capture 70 % was obtained at coal with sulfur content 3.1-3.9 %. In conclusion the fluidized bed technology is very suitable for combustion's characteristics of the Bulgarian coal

Phase equilibria in chemical reactive fluid mixtures

International Nuclear Information System (INIS)

Maurer, Gerd

2011-01-01

Downstream processing is a major part of nearly all processes in the chemical industries. Most separation processes in the chemical (and related) industries for fluid mixtures are based on phase equilibrium phenomena. The majority of separation processes can be modelled assuming that chemical reactions are of no (or very minor) importance, i.e., assuming that the overall speciation remains unchanged during a separation process. However, there are also a large number of industrially important processes where the thermodynamic properties are influenced by chemical reactions. The phase equilibrium of chemical reactive mixtures has been a major research area of the author's group over nearly 40 years. In this contribution, three examples from that research are discussed. The first example deals with the vapour phase dimerisation of carboxylic acids and its consequences on phase equilibrium phenomena and phase equilibrium predictions. The second example deals with the solubility of sour gases (e.g., carbon dioxide and sulfur dioxide) in aqueous solutions of ammonia. That topic has been of interest for many years, e.g., in relation with the gasification and liquefaction of coal and, more recently, with the removal of carbon dioxide from flue gas in the 'chilled ammonia process'. The third example deals with phase equilibrium phenomena in aqueous solutions of polyelectrolytes. It deals with the phenomenon of 'counter ion condensation' and methods to model the Gibbs free energy of such solutions.

Cardiovascular and fluid volume control in humans in space

DEFF Research Database (Denmark)

Norsk, Peter

2005-01-01

on this complex interaction, because it is the only way to completely abolish the effects of gravity over longer periods. Results from space have been unexpected, because astronauts exhibit a fluid and sodium retaining state with activation of the sympathetic nervous system, which subjects during simulations...... by head-down bed rest do not. Therefore, the concept as to how weightlessness affects the cardiovascular system and modulates regulation of body fluids should be revised and new simulation models developed. Knowledge as to how gravity and weightlessness modulate integrated fluid volume control...

Coal-char combustion in a fluidised bed reactor

Energy Technology Data Exchange (ETDEWEB)

Mehrotra, S.P.; Pande, M. [Indian Institute of Technolgy, Kanpur (India)

2001-12-01

Combustion of bituminous coal chars ranging from 0.8 mm to 1.8 mm has been studied in a fluidised bed reactor at temperatures ranging from 500 to 850{sup o}C. The fluidised bed consists of inert sand particles of average size of 0.5 mm and reactive coal char particles. A heat balance has been worked out to calculate the rate of combustion of char from measured incremental changes in the bed temperature during combustion. Investigations on partially burnt particles suggest that the ash layer which builds up around the burning core of char particles is non-flaking and the particles burn in a shrinking core manner. Analysis of rate data indicates that the rate of combustion is controlled by chemical reaction kinetics, though diffusion of oxygen through the bundary layer begins to influence the overall reaction kinetics at higher temperatures. The burnt out time varies linearly with particle size. Activation energy for the chemical reaction control regime is found to be around 68 kJ/mole.

Radioisotope tracer study in a pilot-scale trickle bed reactor

Energy Technology Data Exchange (ETDEWEB)

Pant, H.J.; Pendharkar, A.S. [Bhabha Atomic Research Centre, Isotope Applications Div, Bombay (India); Prasad, J.S.; Maiti, R.N.; Chawla, R.; Lahri, R.N.; Ram Babu, D. [Engineers India Limited, Gurgaon, Haryana (India); Berne, Ph. [CEA Grenoble, DTEN/SAT, 38 (France)

2001-07-01

Trickle bed reactor (TBR) is a reactor in which a liquid and a gas phase flow concurrently downwards through a fixed bed of catalyst particles while the reaction takes place. The trickle bed reactors find a number of applications in petroleum refining, chemical. petro-chemical and bio-chemical processes due to their suitability for hydro-processing operations.The knowledge of radial distribution, mean residence time (MRT). liquid holdup and degree of axial mixing is a basic requirement to evaluate the reactor performance of a TBR, its optimal size, the physical and chemical interactions and the pumping requirements. Measurement and analysis of residence time distribution (RTD) of liquid phase facilitate the determination of these parameters. This paper describes the measurement of RTD of liquid phase in a pilot-scale trickle bed reactor operating at high pressure. Kerosene and nitrogen were used as liquid and gas phase, respectively. Porous alumina catalyst particles were used as packing. Bromine-82 as para-di-bromo benzene was used as a tracer to measure RTD of organic liquid phase. The RTD of kerosene was measured as a function of liquid and gas flow rates and pressure. The axial dispersion model with exchange between active and dead zones was proposed and used to simulate the measured RTD data and model parameters i.e mean residence time ({tau}), Peclet Number (Pe), dynamic fraction of the liquid ({phi}) and the number of transfer units (N) were obtained. The results of the simulations indicated intermediate degree of axial mixing of liquid phase. The RTD predicted by the axial dispersion model with exchange between active and dead zones fits well to the experimentally measured RTD data and thus is a suitable model to describe the dynamics of the liquid phase in TBRs filled with porous catalyst particles. (authors)

Estimation of original reservoir fluid composition prior to aquifer boiling induced by well discharge. Kieki niso ryunyu ni okeru choryu sonai futto izen no chinetsu ryutai no kagaku soshiki no suiteiho

Energy Technology Data Exchange (ETDEWEB)

Seki, Y [Geological Survey of Japan, Tsukuba (Japan)

1991-07-29

A method for estimating chemical composition of original fluid before boiling from the composition of whole fluid flowing into a well is described for the case where an aquifer boiling has begun in a reservoir bed associated with discharge of geothermal fluid from the well (the enthalpy of fluid flowing into the well is larger than an enthalpy possessed by a hot fluid-phase saturated by steam at measured temperatures at flowing point). In this case, it is especially pointed out that the gas-liquid ratio at the well flow-in point becomes larger than the one at boiling. The boiling in the reservoir bed is modelled into two types. One is for larger coefficient of permeation in the reservoir bed where the discharge flow at the well is large, the temperature drop around the well is small, and the boiling is in single stage. The other is for smaller coefficient of permeation in the reservoir bed where the discharge flow and temperature drop are contrastive to the former case, and the boiling is in multi-stage. Calculation processes based on this boiling model are explained with calculation examples. 8 refs.,7 figs.

Characterization of the chemicals used in hydraulic fracturing fluids for wells located in the Marcellus Shale Play.

Science.gov (United States)

Chen, Huan; Carter, Kimberly E

2017-09-15

Hydraulic fracturing, coupled with the advances in horizontal drilling, has been used for recovering oil and natural gas from shale formations and has aided in increasing the production of these energy resources. The large volumes of hydraulic fracturing fluids used in this technology contain chemical additives, which may be toxic organics or produce toxic degradation byproducts. This paper investigated the chemicals introduced into the hydraulic fracturing fluids for completed wells located in Pennsylvania and West Virginia from data provided by the well operators. The results showed a total of 5071 wells, with average water volumes of 5,383,743 ± 2,789,077 gal (mean ± standard deviation). A total of 517 chemicals was introduced into the formulated hydraulic fracturing fluids. Of the 517 chemicals listed by the operators, 96 were inorganic compounds, 358 chemicals were organic species, and the remaining 63 cannot be identified. Many toxic organics were used in the hydraulic fracturing fluids. Some of them are carcinogenic, including formaldehyde, naphthalene, and acrylamide. The degradation of alkylphenol ethoxylates would produce more toxic, persistent, and estrogenic intermediates. Acrylamide monomer as a primary degradation intermediate of polyacrylamides is carcinogenic. Most of the chemicals appearing in the hydraulic fracturing fluids can be removed when adopting the appropriate treatments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Breakthrough of toluene vapours in granular activated carbon filled packed bed reactor

International Nuclear Information System (INIS)

Mohan, N.; Kannan, G.K.; Upendra, S.; Subha, R.; Kumar, N.S.

2009-01-01

The objective of this research was to determine the toluene removal efficiency and breakthrough time using commercially available coconut shell-based granular activated carbon in packed bed reactor. To study the effect of toluene removal and break point time of the granular activated carbon (GAC), the parameters studied were bed lengths (2, 3, and 4 cm), concentrations (5, 10, and 15 mg l -1 ) and flow rates (20, 40, and 60 ml/min). The maximum percentage removal of 90% was achieved and the maximum carbon capacity for 5 mg l -1 of toluene, 60 ml/min flow rate and 3 cm bed length shows 607.14 mg/g. The results of dynamic adsorption in a packed bed were consistent with those of equilibrium adsorption by gravimetric method. The breakthrough time and quantity shows that GAC with appropriate surface area can be utilized for air cleaning filters. The result shows that the physisorption plays main role in toluene removal.

Cryogenic Fluid Management Facility

Science.gov (United States)

Eberhardt, R. N.; Bailey, W. J.

1985-01-01

The Cryogenic Fluid Management Facility is a reusable test bed which is designed to be carried within the Shuttle cargo bay to investigate the systems and technologies associated with the efficient management of cryogens in space. Cryogenic fluid management consists of the systems and technologies for: (1) liquid storage and supply, including capillary acquisition/expulsion systems which provide single-phase liquid to the user system, (2) both passive and active thermal control systems, and (3) fluid transfer/resupply systems, including transfer lines and receiver tanks. The facility contains a storage and supply tank, a transfer line and a receiver tank, configured to provide low-g verification of fluid and thermal models of cryogenic storage and transfer processes. The facility will provide design data and criteria for future subcritical cryogenic storage and transfer system applications, such as Space Station life support, attitude control, power and fuel depot supply, resupply tankers, external tank (ET) propellant scavenging, and ground-based and space-based orbit transfer vehicles (OTV).

Catalytic activity of bed materials from industrial CFB boilers for the decomposition of N2O

International Nuclear Information System (INIS)

Barisic, V.; Klingstedt, F.; Kilpinen, P.; Hupa, M.; Naydenov, A.; Stefanov, P.

2005-01-01

The correlation between the catalytic activity towards N 2 O decomposition and fuel type was studied for the bed materials sampled from the bottom bed of two industrial CFB boilers, a 12MW th and a 550MW th , burning biomass fuels and wastes, alone or as a mixture. It was found that the elemental composition of the surface of the bed material particles changed according to the composition of the ash from the parent fuel. The measured catalytic activity of the bed material samples increased with the amount of the catalytically active oxides (CaO, MgO, Fe 2 O 3 , Al 2 O 3 ). In the case of limestone addition, the activity of the bed material was influenced by both the elemental composition of the fuel, and the ratio between lime and sulfated lime

Dependence of saltation characteristics on bed organisation in numerical simulation

Czech Academy of Sciences Publication Activity Database

Kharlamova, Irina; Vlasák, Pavel

2015-01-01

Roč. 19, č. 1 (2015), s. 177-184 ISSN 1226-4806 R&D Projects: GA ČR GA103/09/1718; GA ČR GAP105/10/1574 Institutional support: RVO:67985874 Keywords : saltation parameters * bed roughness * bed structure * bed load transport * armoured bed Subject RIV: BK - Fluid Dynamics Impact factor: 0.922, year: 2015 http://link.springer.com/content/pdf/10.1007%2Fs12303-014-0029-3.pdf

Progress on pebble bed experimental activity for the HE-FUS3 mock-ups

International Nuclear Information System (INIS)

Dell'Orco, G.; Sansone, L.; Simoncini, M.; Zito, D.

2002-01-01

The EU Long Term for DEMO Programme foresees the qualification of the reference design of the helium cooled pebble bed (HCPB) - test blanket module (TBM) to be tested in ITER Reactor. In this frame, FZK and ENEA have launched many experimental activities for the evaluation of the interactions between the Tritium breeder and neutron multiplier pebble beds and the steel containment walls. Main aim of these activities is the measuring the pebble bed effective thermal conductivity, the wall heat transfer coefficient as well as their dependency from the mechanical constraints. The paper presents the progress of the testing activity and results of the tests on two mock-up, called Tazza and Helichetta, carried out on the HE-FUS3 facility at ENEA Brasimone. (orig.)

An integrated fluid-chemical model towards modeling the formation of intra-luminal thrombus in abdominal aortic aneurysms

Directory of Open Access Journals (Sweden)

Jacopo eBiasetti

2012-07-01

Full Text Available Abdominal Aortic Aneurysms (AAAs are frequently characterized by the presenceof an Intra-Luminal Thrombus (ILT known to influence biochemically and biomechanicallytheir evolution. ILT progression mechanism is still unclear and little is known regardingthe impact on this mechanism of the chemical species transported by blood flow.Chemical agonists and antagonists of platelets activation, aggregation, and adhesion andthe proteins involved in the coagulation cascade (CC may play an important role in ILTdevelopment. Starting from this assumption, the evolution of chemical species involvedin the CC, their relation to coherent vortical structures (VSs and their possible effect onILT evolution have been studied. To this end a fluido-chemical model that simulates theCC through a series of convection-diffusion-reaction (CDR equations has been developed.The model involves plasma-phase and surface bound enzymes and zymogens, and includesboth plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonianincompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinicalobservations showing that the thickest ILT is usually seen in the distal AAA region. Theproposed model, due to its ability to couple the fluid and chemical domains, provides anintegrated mechanochemical picture that potentially could help unveil mechanisms of ILTformation and development.

An investigation of the physical and chemical changes occuring in a Fischer-Tropsch fixed bed catalyst during hydrocarbon synthesis

International Nuclear Information System (INIS)

Duvenhage, D.J.

1990-01-01

Deactivation studies: making use of fixed bed reactors, wet chemical analysis, surface area, pore volume determinations and X-ray diffraction spectrometry, scanning electron microscope spectrometry and secondary ion mass spectrometry techniques; were performed on a low temperature iron Fischer-Tropsch catalyst. It was revealed that this catalyst is mainly deactivated by sulphur poisoning, oxidation of the catalytic reactive phases, sintering of the iron crystallites and to a lesser extent deactivation through fouling of the catalytic surface by carbonaceous deposits. It was found that the top entry section of the catalyst bed deactivated relatively fast, the bottom exit section also deactivated, but not as fast as the top section. The central portion of the catalyst bed was least affected. Sulphur contaminants in the feed gas, even though present in only minute quantities, results in a loss of catalyst performance of the top section of the catalyst bed, while water, produced as a product from the Fischer-Tropsch reaction, oxidized and sintered the catalyst over the bottom section of the catalyst bed. 88 figs., 7 tabs., 224 refs

Chemical deposition methods using supercritical fluid solutions

Science.gov (United States)

Sievers, Robert E.; Hansen, Brian N.

1990-01-01

A method for depositing a film of a desired material on a substrate comprises dissolving at least one reagent in a supercritical fluid comprising at least one solvent. Either the reagent is capable of reacting with or is a precursor of a compound capable of reacting with the solvent to form the desired product, or at least one additional reagent is included in the supercritical solution and is capable of reacting with or is a precursor of a compound capable of reacting with the first reagent or with a compound derived from the first reagent to form the desired material. The supercritical solution is expanded to produce a vapor or aerosol and a chemical reaction is induced in the vapor or aerosol so that a film of the desired material resulting from the chemical reaction is deposited on the substrate surface. In an alternate embodiment, the supercritical solution containing at least one reagent is expanded to produce a vapor or aerosol which is then mixed with a gas containing at least one additional reagent. A chemical reaction is induced in the resulting mixture so that a film of the desired material is deposited.

Saline flushing fluids restricting contamination of the near-face zone

Energy Technology Data Exchange (ETDEWEB)

Weil, W

1982-01-01

Questions are covered which concern the characteristics and main properties of saline solutions without solid phase and their use as flushing fluids. Attention is drawn to the fact that these solutions are universally used in flushing and other operations of wells with high gradients of bed pressures, and also in those cases where the oil and gas levels are especially sensitive to negative influence of traditional clay solutions which cause irreversible decrease in permeability of the reservoirs through contamination and plugging of the pores in the near-face zone, and consequently, influence the decrease in bed productivity. The described methods and chemical reagents decrease the filtering of these solutions in the reservoirs, improve viscosity and stabilize the near-face zone.

Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis

International Nuclear Information System (INIS)

Trauth, H.A.; Heimes, K.; Schubotz, R.; von Wichert, P.

1986-01-01

Roentgenograms and gallium-67 scans and gallium-67 counts of BAL fluid samples, together with differential cell counts, have proved to be useful in assessing activity and lung involvement in sarcoidosis. In active pulmonary sarcoidosis gallium-67 scans are usually positive. Quantitation of gallium-67 uptake in lung scans, however, may be difficult. Because gallium-67 uptake and cell counts in BAL fluid may be correlated, we set out to investigate gallium-67 activity in BAL fluid recovered from patient of different groups. Sixteen patients with recently diagnosed and untreated sarcoidosis, nine patients with healthy lungs, and five patients with CFA were studied. Gallium-67 uptake of the lung, gallium-67 activity in the lavage fluid, SACE and LACE levels, and alpha 1-AT activity were measured. Significantly more gallium-67 activity was found in BAL fluid from sarcoidosis patients than in that from CFA patients (alpha = .001) or patients with healthy lungs (alpha = .001). Gallium-67 activity in BAL fluid could be well correlated with the number of lymphocytes in BAL fluid, but poorly with the number of macrophages. Subjects with increased levels of SACE or serum alpha 1-AT showed higher lavage gallium-67 activity than did normals, but no correlation could be established. High gallium-67 activity in lavage fluid may be correlated with acute sarcoidosis or physiological deterioration; low activity denotes change for the better. The results show that gallium-67 counts in BAL fluid reflects the intensity of gallium-67 uptake and thus of activity of pulmonary sarcoidosis

CFD analysis of hydrodynamic studies of a bubbling fluidized bed

Science.gov (United States)

Rao, B. J. M.; Rao, K. V. N. S.; Ranga Janardhana, G.

2018-03-01

Fluidization velocity is one of the most important parameter to characterize the hydrodynamic studies of fluidized bed asit determines different flow regimes. Computational Fluid Dynamics simulations are carriedfor a cylindrical bubbling fluidized bed with a static bed height 1m with 0.150m diameter of gasification chamber. The parameter investigated is fluidization velocity in range of 0.05m/s to 0.7m/s. Sand with density 2600kg/m3 and with a constant particle diameter of sand 385μm is employed for all the simulations. Simulations are conducted using the commercial Computational Fluid Dynamics software, ANSYS-FLUENT.The bubbling flow regime is appeared above the air inlet velocity of 0.2m/s. Bubbling character is increased with increase in inlet air velocities indicated by asymmetrical fluctuations of volume fractions in radial directions at different bed heights

Fluid flow for chemical and process engineers

CERN Document Server

Holland, F

1995-01-01

This major new edition of a popular undergraduate text covers topics of interest to chemical engineers taking courses on fluid flow. These topics include non-Newtonian flow, gas-liquid two-phase flow, pumping and mixing. It expands on the explanations of principles given in the first edition and is more self-contained. Two strong features of the first edition were the extensive derivation of equations and worked examples to illustrate calculation procedures. These have been retained. A new extended introductory chapter has been provided to give the student a thorough basis to understand the methods covered in subsequent chapters.

Double stratification effects in chemically reactive squeezed Sutterby fluid flow with thermal radiation and mixed convection

Directory of Open Access Journals (Sweden)

S. Ahmad

2018-03-01

Full Text Available A current analysis is carried out to study theoretically the mixed convection characteristics in squeezing flow of Sutterby fluid in squeezed channel. The constitutive equation of Sutterby model is utilized to characterize the rheology of squeezing phenomenon. Flow characteristics are explored with dual stratification. In flowing fluid which contains heat and mass transport, the first order chemical reaction and radiative heat flux affect the transport phenomenon. The systems of non-linear governing equations have been modulating which then solved by mean of convergent approach (Homotopy Analysis Method. The graphs are reported and illustrated for emerging parameters. Through graphical explanations, drag force, rate of heat and mass transport are conversed for different pertinent parameters. It is found that heat and mass transport rate decays with dominant double stratified parameters and chemical reaction parameter. The present two-dimensional examination is applicable in some of the engineering processes and industrial fluid mechanics. Keywords: Squeezing flow, Sutterby fluid model, Mixed convection, Double stratification, Thermal radiation, Chemical reaction

Real-time process monitoring in a semi-continuous fluid-bed dryer - microwave resonance technology versus near-infrared spectroscopy.

Science.gov (United States)

Peters, Johanna; Teske, Andreas; Taute, Wolfgang; Döscher, Claas; Höft, Michael; Knöchel, Reinhard; Breitkreutz, Jörg

2018-02-15

The trend towards continuous manufacturing in the pharmaceutical industry is associated with an increasing demand for advanced control strategies. It is a mandatory requirement to obtain reliable real-time information on critical quality attributes (CQA) during every process step as the decision on diversion of material needs to be performed fast and automatically. Where possible, production equipment should provide redundant systems for in-process control (IPC) measurements to ensure continuous process monitoring even if one of the systems is not available. In this paper, two methods for real-time monitoring of granule moisture in a semi-continuous fluid-bed drying unit are compared. While near-infrared (NIR) spectroscopy has already proven to be a suitable process analytical technology (PAT) tool for moisture measurements in fluid-bed applications, microwave resonance technology (MRT) showed difficulties to monitor moistures above 8% until recently. The results indicate, that the newly developed MRT sensor operating at four resonances is capable to compete with NIR spectroscopy. While NIR spectra were preprocessed by mean centering and first derivative before application of partial least squares (PLS) regression to build predictive models (RMSEP = 0.20%), microwave moisture values of two resonances sufficed to build a statistically close multiple linear regression (MLR) model (RMSEP = 0.07%) for moisture prediction. Thereby, it could be verified that moisture monitoring by MRT sensor systems could be a valuable alternative to NIR spectroscopy or could be used as a redundant system providing great ease of application. Copyright © 2017 Elsevier B.V. All rights reserved.

The characteristics of bed agglomeration during fluidized bed combustion of eucalyptus bark

International Nuclear Information System (INIS)

Chaivatamaset, Pawin; Tia, Suvit

2015-01-01

The bed agglomeration behaviors were investigated experimentally when eucalyptus bark was burning tested in a laboratory scale fluidized bed reactor. The focuses of this work were the influences of operating conditions and bed materials on the bed agglomeration tendency and the elucidation in the behaviors of fuel inorganic elements and the governing mode of the agglomeration. It was found that the defluidization caused by the bed agglomeration was clearly detectable from the decrease in measured bed pressure. The growth of bed particle and accumulation of agglomerates during combustion provided the partial to complete defluidization. The defluidization was promoted by the increase of bed temperature and bed particle size, and the decrease of fluidizing air velocity. The SEM-EDS analyses revealed that the bed agglomeration was mainly attributed to the formation of potassium silicate compounds as liquid phase during the combustion. This was initiated by the chemical reaction between the bed particle and the released ash constituents. In this study, the inorganic migration from fuel particle to bed particle was likely dominated by the condensation/reaction. The thermodynamic examination by ternary phase diagram analysis corroborated that the liquid phase formation of the ash derived materials controlled the agglomeration. The alumina sand prevented the bed agglomeration since it was inactive in the formation of viscous molten substances during combustion at the observed temperatures. - Highlights: • The behaviors of bed agglomeration were studied during the fluidized bed combustion of eucalyptus bark. • The increase in bed temperature and sand size, and the decrease of air velocity promoted bed defluidization. • The formation of molten potassium silicate compounds conduced to the bed agglomeration. • Condensation/reaction was the dominant inorganic migration mechanism from fuel particle to bed particle. • The alumina sand prevented effectively the bed

Adsorption of aromatic amino acids in a fixed bed column

Directory of Open Access Journals (Sweden)

Cremasco M.A.

2003-01-01

Full Text Available Phenylalanine (Phe and tyrosine (Tyr are two of the twenty amino acids in proteins; they are classified as aromatic amino acids, because both have a benzene ring in their structures. These amino acids are important in the synthesis of several biologically active amines, such as beta-endorphin, a neurotransmitter. Amino acids can be separated by ion-exchange chromatography. In this case, it is important that fixed-bed adsorber design adequately predict the breakthrough curve. This work presents a mathematical model for both fluid and porous phases. In the solution proposed for this model the liquid-phase concentration inside the particles is solved analytically and is related to the liquid-phase concentration in the bed using Duhamel's theorem. The solution for liquid-phase concentration in the bed is then solved numerically instead of analytically. The basic mass transfer parameters are from the literature. The results from the model are compared with those obtained experimentally using Phe and Tyr diluted in aqueous solutions in a fixed bed of PVP (poly-4-vinylpyridine resin.

Fluidized bed combustion research and development in Sweden: A historical survey

Directory of Open Access Journals (Sweden)

Leckner Bo.

2003-01-01

Full Text Available A survey is made on research and development related to fluidized bed boilers in Sweden during the past two decades, where several Swedish enterprises took part: Generator, Götaverken, Stal Laval (ABB Carbon and Studsvik. Chalmers University of Technology contributed in the field of research related to emissions, heat transfer and fluid dynamics, and some results from this activity are briefly summarized.

Modeling and Simulation of a lab-scale Fluidised Bed

Directory of Open Access Journals (Sweden)

Britt Halvorsen

2002-04-01

Full Text Available The flow behaviour of a lab-scale fluidised bed with a central jet has been simulated. The study has been performed with an in-house computational fluid dynamics (CFD model named FLOTRACS-MP-3D. The CFD model is based on a multi-fluid Eulerian description of the phases, where the kinetic theory for granular flow forms the basis for turbulence modelling of the solid phases. A two-dimensional Cartesian co-ordinate system is used to describe the geometry. This paper discusses whether bubble formation and bed height are influenced by coefficient of restitution, drag model and number of solid phases. Measurements of the same fluidised bed with a digital video camera are performed. Computational results are compared with the experimental results, and the discrepancies are discussed.

Acoustic wave propagation in fluids with coupled chemical reactions

International Nuclear Information System (INIS)

Margulies, T.S.; Schwarz, W.H.

1984-08-01

This investigation presents a hydroacoustic theory which accounts for sound absorption and dispersion in a multicomponent mixture of reacting fluids (assuming a set of first-order acoustic equations without diffusion) such that several coupled reactions can occur simultaneously. General results are obtained in the form of a biquadratic characteristic equation (called the Kirchhoff-Langevin equation) for the complex propagation variable chi = - (α + iω/c) in which α is the attenuation coefficient, c is the phase speed of the progressive wave and ω is the angular frequency. Computer simulations of sound absorption spectra have been made for three different chemical systems, each comprised of two-step chemical reactions using physico-chemical data available in the literature. The chemical systems studied include: (1) water-dioxane, (2) aqueous solutions of glycine and (3) cobalt polyphosphate mixtures. Explicit comparisons are made between the exact biquadratic characteristic solution and the approximate equation (sometimes referred to as a Debye equation) previously applied to interpret the experimental data for the chemical reaction contribution to the absorption versus frequency. The relative chemical reaction and classical viscothermal contributions to the sound absorption are also presented. Several discrepancies that can arise when estimating thermodynamic data (chemical reaction heats or volume changes) for multistep chemical reaction systems when making dilute solution or constant density assumptions are discussed

Activated Carbon Adsorption Characteristics of Multi-component Volatile Organic compounds in a Fixed Bed Adsorption Bed

Energy Technology Data Exchange (ETDEWEB)

Cho, Jong Hoon; Rhee, Young Woo [Chungnam National University, Daejeon (Korea, Republic of); Lee, Sihyun [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2016-04-15

This study aims to examine absorption characteristics of toluene, isopropyl alcohol (IPA), ethyl acetate (EA), and ternary-compounds, all of which are widely used in industrial processes, by means of four types of commercial activated carbon substances. It turned out that among the three types of volatile organic compounds, the breakthrough point of activated carbon and that of IPA, whose affinity was the lowest, were the lowest, and then that of EA and that of toluene in the order. With the breakthrough point of IPA, which was the shortest, as the standard, changes in the breakthrough points of unary-compounds, binary-compounds, and ternary-compounds were examined. As a result, it turned out that the larger the number of elements, the lower the breakthrough point. This resulted from competitive adsorption, that is, substitution of substances with a low level of affinity with those with a high level of affinity. Hence, the adsorption of toluene-IPA-EA and ternary-compounds require a design of the activated carbon bed based on the breakthrough of IPA, and in the design of activated carbon beds in actual industries as well, a substance whose level of affinity is the lowest needs to be the standard.

Recent advances in fluidized bed drying

Science.gov (United States)

Haron, N. S.; Zakaria, J. H.; Mohideen Batcha, M. F.

2017-09-01

Fluidized bed drying are very well known to yield high heat and mass transfer and hence adopted to many industrial drying processes particularly agricultural products. In this paper, recent advances in fluidized bed drying were reviewed and focus is given to the drying related to the usage of Computational Fluid Dynamics (CFD). It can be seen that usage of modern computational tools such as CFD helps to optimize the fluidized bed dryer design and operation for lower energy consumption and thus better thermal efficiency. Among agricultural products that were reviewed in this paper were oil palm frond, wheat grains, olive pomace, coconut, pepper corn and millet.

Investigation of the fluidized bed-chemical vapor deposition (FBCVD) process using CFD-DEM method

International Nuclear Information System (INIS)

Liu Malin; Liu Rongzheng; Wen Yuanyun; Liu Bing; Shao Youlin

2014-01-01

The CFD-DEM-CVD multiscale coupling simulation concept was proposed based on the mass/momentum/energy transfer involved in the FB-CVD process. The pyrolysis process of the reaction gas in the spouted bed can be simulated by CFD method, then the concentration field and velocity field can be extracted and coupled with the particle movement behavior which can be simulated by DEM. Particle deposition process can be described by the CVD model based on particle position, velocity and neighboring gas concentration. This multiscale coupling method can be implemented in the Fluent@-EDEM@ software with their UDF (User Definition Function) and API (Application Programming Interface). Base on the multiscale coupling concept, the criterion for evaluating FB-CVD process is given. At first, the volume in the coating furnace is divided into two parts (active coating area and non-active coating area) based on simulation results of chemical pyrolysis process. Then the residence time of all particles in the active coating area can be obtained using the CFD-DEM simulation method. The residence time distribution can be used as a criterion for evaluating the gas-solid contact efficiency and operation performance of the coating furnace. At last different coating parameters of the coating furnace are compared based on the proposed criterion. And also, the future research emphasis is discussed. (author)

Comparison of Three Bed Bug Management Strategies in a Low-Income Apartment Building

Directory of Open Access Journals (Sweden)

Changlu Wang

2012-04-01

Full Text Available Bed bug (Cimex lectularius L. infestations are currently controlled by a variety of non-chemical and chemical methods. There have been few studies on the comparative effectiveness of these control techniques. We evaluated three bed bug management strategies in an apartment building: (1 non-chemical methods only (n = 9; (2 insecticides only (n = 6; and (3 integrated pest management including both non-chemical methods and insecticides (n = 9. The apartments were one-bedroom units occupied by seniors or people with disabilities. Bed bug numbers in each apartment were determined by visual inspection and/or installing intercepting devices under bed and sofa legs. The median (min, max bed bug counts in the non-chemical methods only, insecticides only, and integrated pest management (IPM treatment were: 4 (1, 57, 19 (1, 250, and 14 (1, 219, respectively prior to the treatments. The apartments were retreated if found necessary during biweekly to monthly inspections. After 10 weeks, bed bugs were found to be eliminated from 67, 33, and 44% of the apartments in the three treatment groups, respectively. The final (after 10 weeks median (min, max bed bug counts in the non-chemical methods only, insecticides only, and IPM treatment were: 0 (0, 134, 11.5 (0, 58, and 1 (0, 38, respectively. There were no significant differences in the speed of bed bug count reduction or the final bed bug counts. Lack of resident cooperation partially contributed to the failure in eliminating bed bugs from some of the apartments. Results of this study suggest that non-chemical methods can effectively eliminate bed bugs in lightly infested apartments.

Towards establishing the rheology of a sediment bed

Science.gov (United States)

Biegert, Edward; Vowinckel, Bernhard; Meiburg, Eckart

2017-11-01

In order to gain a better understanding of erosion, we have conducted numerical simulations of particle-resolved flows similar to the experiments of Aussillous et al. (2013), which involve laminar pressure-driven flows over erodible sediment beds. These simulations allow us to resolve velocity profiles and stresses of the fluid-particle mixtures within and above the sediment bed, which can be difficult or impossible to measure experimentally. Thus, we can begin investigating the rheology of the fluid-particle mixtures. In particular, we compare the effective viscosity as a function of volume fraction to existing models, such as those of Eilers (1943), Morris and Boulay (1999), and Boyer et al. (2011).

Numerical simulations on self-leveling behaviors with cylindrical debris bed

Energy Technology Data Exchange (ETDEWEB)

Guo, Liancheng, E-mail: Liancheng.guo@kit.edu [Institute for Nuclear and Energy Technologies (IKET), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Morita, Koji, E-mail: morita@nucl.kyushu-u.ac.jp [Faculty of Engineering, Kyushu University, 2-3-7, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Tobita, Yoshiharu, E-mail: tobita.yoshiharu@jaea.go.jp [Fast Reactor Safety Technology Development Department, Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki 311-1393 (Japan)

2017-04-15

Highlights: • A 3D coupled method was developed by combining DEM with the multi-fluid model of SIMMER-IV code. • The method was validated by performing numerical simulations on a series of experiments with cylindrical particle bed. • Reasonable agreement can demonstrate the applicability of the method in reproducing the self-leveling behavior. • Sensitivity analysis on some model parameters was performed to assess their impacts. - Abstract: The postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal fast reactors (LMFRs). In the CDAs, core debris may settle on the core-support structure and form conic bed mounds. Then debris bed can be levelled by the heat convection and vaporization of surrounding coolant sodium, which is named “self-leveling behavior”. The self-leveling behavior is a crucial issue in the safety analysis, due to its significant effect on the relocation of molten core and heat-removal capability of the debris bed. Considering its complicate multiphase mechanism, a comprehensive computational tool is needed to reasonably simulate transient particle behavior as well as thermal-hydraulic phenomenon of surrounding fluid phases. The SIMMER program is a successful computer code initially developed as an advanced tool for CDA analysis of LMFRs. It is a multi-velocity-field, multiphase, multicomponent, Eulerian, fluid dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron kinetics model. Until now, the code has been successfully applied in numerical simulations for reproducing key thermal-hydraulic phenomena involved in CDAs as well as performing reactor safety assessment. However, strong interactions between massive solid particles as well as particle characteristics in multiphase flows were not taken into consideration in its fluid-dynamics models. To solve this problem, a new method is developed by combining the discrete element method (DEM

Three phase Eulerian-granular model applied on numerical simulation of non-conventional liquid fuels combustion in a bubbling fluidized bed

Directory of Open Access Journals (Sweden)

Nemoda Stevan Đ.

2016-01-01

Full Text Available The paper presents a two-dimensional CFD model of liquid fuel combustion in bubbling fluidized bed. The numerical procedure is based on the two-fluid Euler-Euler approach, where the velocity field of the gas and particles are modeled in analogy to the kinetic gas theory. The model is taking into account also the third - liquid phase, as well as its interaction with the solid and gas phase. The proposed numerical model comprise energy equations for all three phases, as well as the transport equations of chemical components with source terms originated from the component conversion. In the frame of the proposed model, user sub-models were developed for heterogenic fluidized bed combustion of liquid fuels, with or without water. The results of the calculation were compared with experiments on a pilot-facility (power up to 100 kW, combusting, among other fuels, oil. The temperature profiles along the combustion chamber were compared for the two basic cases: combustion with or without water. On the basis of numerical experiments, influence of the fluid-dynamic characteristics of the fluidized bed on the combustion efficiency was analyzed, as well as the influence of the fuel characteristics (reactivity, water content on the intensive combustion zone. [Projekat Ministarstva nauke Republike Srbije, br. TR33042: Improvement of the industrial fluidized bed facility, in scope of technology for energy efficient and environmentally feasible combustion of various waste materials in fluidized bed

A mathematical model for supplying air-cooling for a building using a packed bed

Energy Technology Data Exchange (ETDEWEB)

Marewo, G.T. [Zimbabwe Univ., Mathematics Dept., Harare (Zimbabwe); Henwood, D.J. [School of Computing and Mathematical Sciences, Brighton (United Kingdom)

2006-01-15

The cooling system at the Harare International School uses a packed bed system for storing the coldness of the night-time to be used later for day-time air-conditioning. A two-phase mathematical model is described for the packed bed which includes heat dispersion in the fluid, and heat loss to the environment. This is in contrast to other studies, where at least one of these terms is neglected to simplify the mathematical model. A numerical method for obtaining a solution is proposed and implemented. Using measured inlet temperatures, the measured and predicted outlet temperatures of the bed show good trend agreement. The differences in detail are examined through sensitivity analyses for both the heat convection transfer and air velocity. It is apparent that adjusting these parameters can increase the agreement between the predicted and measured data. A parametric study for heat storage with various materials and bed sizes is given, which indicates how the code may be used as a tool for improving design and operational parameters. Practical application: A mathematical model of a packed bed is described; the bed is made up of fluid flowing over solid material with heat interchange between the two. The solid material is idealized as spheres and the fluid temperature is assumed uniform in a cross-section of the bed. The model includes heat interchange between the bed and its surrounding environment and allows for time varying fluid velocity. The input data is the inlet temperature to the bed, which may be measured. The comparison with measured data may be helpful to anyone attempting to develop and test a similar model. The sensitivity tests give an understanding of the significance of some of the parameters involved. The Appendix gives a mathematical statement of the problem and an outline of an approach to developing computer code for a numerical solution. (Author)

Post-combustion CO2 capture with activated carbons using fixed bed adsorption

Science.gov (United States)

Al Mesfer, Mohammed K.; Danish, Mohd; Fahmy, Yasser M.; Rashid, Md. Mamoon

2018-03-01

In the current work, the capturing of carbon dioxide from flue gases of post combustion emission using fixed bed adsorption has been carried out. Two grades of commercial activated carbon (sorbent-1 and sorbent-2) were used as adsorbent. Feed consisting of CO2 and N2 mixture was used for carrying out the adsorption. The influence of bed temperature, feed rate, equilibrium partial pressure and initial % CO2 in feed were considered for analyzing adsorption-desorption process. It was found that the total adsorption-desorption cycle time decreases with increased column temperature and feed rates. The time required to achieve the condition of bed saturation decreases with increased bed temperature and feed rates. The amount of CO2 adsorbed/Kg of the adsorbent declines with increased bed temperature with in studied range for sorbent-1 and sorbent-2. It was suggested that the adsorption capacity of the both the sorbents increases with increased partial pressure of the gas.

Modelling of Mass Transfer Phenomena in Chemical and Biochemical Reactor Systems using Computational Fluid Dynamics

DEFF Research Database (Denmark)

Larsson, Hilde Kristina

the velocity and pressure distributions in a fluid. CFD also enables the modelling of several fluids simultaneously, e.g. gas bubbles in a liquid, as well as the presence of turbulence and dissolved chemicals in a fluid, and many other phenomena. This makes CFD an appreciated tool for studying flow structures......, mixing, and other mass transfer phenomena in chemical and biochemical reactor systems. In this project, four selected case studies are investigated in order to explore the capabilities of CFD. The selected cases are a 1 ml stirred microbioreactor, an 8 ml magnetically stirred reactor, a Rushton impeller...... and an ion-exchange reaction are also modelled and compared to experimental data. The thesis includes a comprehensive overview of the fundamentals behind a CFD software, as well as a more detailed review of the fluid dynamic phenomena investigated in this project. The momentum and continuity equations...

Squeeze-film flow between a flat impermeable bearing and an anisotropic porous bed

Science.gov (United States)

Karmakar, Timir; Raja Sekhar, G. P.

2018-04-01

We consider a theoretical model of the squeeze film in the presence of a porous bed. The gap between the porous bed and the bearing is assumed to be filled with a Newtonian fluid. We use the Navier-Stokes equation in the fluid region and the Darcy equation in the fluid filled porous region. Lubrication approximation is used to derive the corresponding evolution equation for the film thickness. We use G. S. Beavers and D. D. Joseph ["Boundary conditions at a naturally permeable wall," J. Fluid. Mech. 30, 197-207 (1967)] and M. Le Bars and M. G. Worster ["Interfacial conditions between a pure fluid and a porous medium: Implications for binary alloy solidification," J. Fluid. Mech. 550, 149-173 (2006)] condition at the liquid porous interface and present a detailed analysis on the corresponding impact. We assume that the porous bed is anisotropic in nature with permeabilities K2 and K1 along the principal axes. Accordingly, the anisotropic angle ϕ is taken as the angle between the horizontal direction and principal axis with permeability K2. We show that the anisotropic permeability ratio and the anisotropic angle make a significant influence on the contact time, flux, velocity, etc. Contact time to meet the porous bed when a bearing approaches under a constant prescribed load is estimated. We present some important findings (relevant to the knee joint) based on the anisotropic properties of the human cartilage. For a prescribed constant load, we have estimated the time duration, during which a healthy human knee remains fluid lubricated.

Transient quenching of superheated debris beds during bottom reflood

International Nuclear Information System (INIS)

Tutu, N.K.; Ginsberg, T.; Klein, J.; Schwarz, C.E.; Klages, J.

1984-01-01

The experimental data suggest that for small liquid supply rate and low initial particle temperature, the bed quench process is a one-dimensional frontal phenomenon. The bed heat flux is constant during most of the duration of the quench period. The range of conditions which display one-dimensional frontal cooling characteristics is identified as the deep bed regime of bed quenching, and a limiting mathematical model was developed to describe the observed behavior. For large liquid supply rate and high initial bed temperature, the bed quench process is a complex phenomenon. Under these conditions, the bed heat flux displays a nonuniform time dependence. In order to characterize this shallow bed regime, it was necessary to develop a detailed transient model of the coolant-debris interaction. This model, while developed for the shallow bed regime, also applies to the deep bed regime. Numerical computations clearly demonstrate the importance of developing a general reliable model for the solid-fluid heat transfer coefficients

Using Passive Polyethylene Samplers to Evaluate Chemical Activities Controlling Fluxes and Bioaccumulation of Organic Contaminants in Bed Sediments

Science.gov (United States)

2010-11-01

often yielding uncertain information regarding the degree of hazard and the spatial extent of the problem. Subsequent remediation commonly involves...suited to sampling organic contaminants across bed-water interfaces and down into the sediment bed. The methodology must yield data that are more...surrogate standards were Soxhlet extracted for 24 hr using 450 mL of dichloromethane. Extracts were reduced to approximately 10 mL using the rotary

Coarse grid simulation of bed expansion characteristics of industrial-scale gas–solid bubbling fluidized beds

NARCIS (Netherlands)

Wang, J.; van der Hoef, Martin Anton; Kuipers, J.A.M.

2010-01-01

Two-fluid modeling of the hydrodynamics of industrial-scale gas-fluidized beds proves a long-standing challenge for both engineers and scientists. In this study, we suggest a simple method to modify currently available drag correlations to allow for the effect of unresolved sub-grid scale

Effect of Separation Method on Chemical Composition and Insecticidal Activity of Lamiaceae Isolates

Czech Academy of Sciences Publication Activity Database

Sajfrtová, Marie; Sovová, Helena; Karban, Jindřich; Rochová, Kristina; Pavela, R.; Barnet, M.

2013-01-01

Roč. 47, MAY (2013), s. 69-77 ISSN 0926-6690 R&D Projects: GA MŠk 2B06049; GA TA ČR TA01010578 Institutional support: RVO:67985858 Keywords : supercritical fluid extraction * iInsecticidal activity * lamiaceae Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.208, year: 2013

Physiological responses of women to simulated weightlessness: A review of the first female bed-rest study

Science.gov (United States)

Sandler, H.; Winter, D. L.

1978-01-01

Subjects were exposed to centrifugation, to lower body negative pressure (LBNP), and to exericse stress both before and after bed rest. Areas studied were centrifugation tolerance, fluid electrolyte changes and hematology, tolerance to LBNP, physical working capacity, biochemistries, blood fibrinolytic activity, female metabolic and hormonal responses, circadian alterations, and gynecology. Results were compared with the responses observed in similarly bed-rested male subjects. The bed-rested females showed deconditioning responses similar to those of the males, although with some differences. Results indicate that women are capable of coping with exposure to weightlessness and, moreover, that they may be more sensitive subjects for evaluating countermeasures to weightlessness and developing criteria for assessing applicants for shuttle voyages.

Numerical simulations of heterogeneous chemical reactions coupled to fluid flow in varying thermal fields

International Nuclear Information System (INIS)

Carnahan, C.L.

1991-11-01

A numerical simulator of reactive chemical transport with coupling from precipitation-dissolution reactions to fluid flow, via changes of porosity and permeability, is applied to precipitation-dissolution of quartz and calcite in spatially and temporally variable fields of temperature. Significant effects on fluid flow are found in the quartz-silicic acid system in the presence of persistent, strong gradient of temperature. Transient heat flow in the quartz-silicic acid system and in a calcite-calcium ion-carbonato species system produces vanishingly small effects on fluid flow

Determination of viscosity in recirculating fluidized bed using radioactive tracer

International Nuclear Information System (INIS)

Silva, G.G. da.

1986-01-01

The use of radioactive tracer for measuring viscosity is proposed. The methodology relates the terminal velocity of a radioactive sphere in interior of fluid with the viscosity, which can be a fluidized bed or total flow of solids. The arrangement is composed by two γ detectors placed externally and along the bed. Both detectors are coupled by amplifier to electronic clock. The drop time of sphere between two detectors is measured. The bed viscosity two detectors is measured. The bed viscosity is calculated from mathematical correlations of terminal velocity of the sphere. (M.C.K.)

Fluid physico-chemical properties influence capture and diet in Nepenthes pitcher plants.

Science.gov (United States)

Bazile, Vincent; Le Moguédec, Gilles; Marshall, David J; Gaume, Laurence

2015-03-01

Nepenthes pitcher plants have evolved modified leaves with slippery surfaces and enzymatic fluids that trap and digest prey, faeces and/or plant detritus. Although the fluid's contribution to insect capture is recognized, the physico-chemical properties involved remain underexplored and may vary among species, influencing their diet type. This study investigates the contributions of acidity and viscoelasticity in the fluid's capture efficiency of two ant and two fly species in four Nepenthes species with different nutrition strategies. Four Nepenthes species were studied, namely N. rafflesiana, N. gracilis, N. hemsleyana and N. ampullaria. Fluid was collected from pitchers of varying ages from plants growing in the field and immediately transferred to glass vials, and individual ants (tribe Campotini, Fomicinae) and flies (Calliphora vomitoria and Drosophila melanogaster) were dropped in and observed for 5 min. Water-filled vials were used as controls. Survival and lifetime data were analysed using models applied to right-censored observations. Additional laboratory experiments were carried out in which C. vomitoria flies were immersed in pH-controlled aqueous solutions and observed for 5 min. Pitcher fluid differed among Nepenthes species as regards insect retention capacity and time-to-kill, with differences observed between prey types. Only the fluids of the reputedly insectivorous species were very acidic and/or viscoelastic and retained significantly more insects than the water controls. Viscoelastic fluids were fatal to flies and were able to trap the broadest diversity of insects. Younger viscoelastic fluids showed a better retention ability than older fluids, although with less rapid killing ability, suggesting that a chemical action follows a mechanical one. Insect retention increased exponentially with fluid viscoelasticity, and this happened more abruptly and at a lower threshold for flies compared with ants. Flies were more often retained if they

Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

Directory of Open Access Journals (Sweden)

Samuel Bayham

2017-08-01

Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

Exercise-induced pyruvate dehydrogenase activation is not affected by 7 days of bed rest

DEFF Research Database (Denmark)

Kiilerich, Kristian; Jørgensen, Stine Ringholm; Biensø, Rasmus Sjørup

2011-01-01

To test the hypothesis that physical inactivity impairs the exercise-induced modulation of pyruvate dehydrogenase (PDH), 6 healthy normally physically active male subjects completed 7 days of bed rest. Before and immediately after the bed rest, the subjects completed an OGTT and a one-legged knee...

Numerical solution of chemically reactive non-Newtonian fluid flow: Dual stratification

Science.gov (United States)

Rehman, Khalil Ur; Malik, M. Y.; Khan, Abid Ali; Zehra, Iffat; Zahri, Mostafa; Tahir, M.

2017-12-01

We have found that only a few attempts are available in the literature relatively to the tangent hyperbolic fluid flow induced by stretching cylindrical surfaces. In particular, temperature and concentration stratification effects have not been investigated until now with respect to the tangent hyperbolic fluid model. Therefore, we have considered the tangent hyperbolic fluid flow induced by an acutely inclined cylindrical surface in the presence of both temperature and concentration stratification effects. To be more specific, the fluid flow is attained with the no slip condition, which implies that the bulk motion of the fluid particles is the same as the stretching velocity of a cylindrical surface. Additionally, the flow field situation is manifested with heat generation, mixed convection and chemical reaction effects. The flow partial differential equations give a complete description of the present problem. Therefore, to trace out the solution, a set of suitable transformations is introduced to convert these equations into ordinary differential equations. In addition, a self-coded computational algorithm is executed to inspect the numerical solution of these reduced equations. The effect logs of the involved parameters are provided graphically. Furthermore, the variations of the physical quantities are examined and given with the aid of tables. It is observed that the fluid temperature is a decreasing function of the thermal stratification parameter and a similar trend is noticed for the concentration via the solutal stratification parameter.

Film Coating of Nifedipine Extended Release Pellets in a Fluid Bed Coater with a Wurster Insert

Directory of Open Access Journals (Sweden)

Luciane Franquelin Gomes de Souza

2014-01-01

Full Text Available The objective of this work was to study the coating process of nifedipine extended release pellets using Opadry and Opadry II, in a fluid bed coater with a Wurster insert. The coating process was studied using a complete experimental design of two factors at two levels for each polymer. The variables studied were the inlet air temperature and the coating suspension flow rate. The agglomerate fraction and coating efficiency were the analyzed response variables. The air temperature was the variable that most influenced the coating efficiency for both polymers. In addition, a study of the dissolution profiles of coated and uncoated pellets using 0.5% sodium lauryl sulfate in simulated gastric fluid without enzymes (pH 1.2 was conducted. The results showed a prolonged release profile for the coated and uncoated pellets that was very similar to the standards established by the U.S. Pharmacopoeia. The drug content and the release profiles were not significantly affected by storage at 40°C and 75% relative humidity. However, when exposed to direct sunlight and fluorescent light (light from fluorescent bulbs, the coated pellets lost only 5% of the drug content, while the uncoated ones lost more than 35%; furthermore, the dissolution profile of the uncoated pellets was faster.

Film Coating of Nifedipine Extended Release Pellets in a Fluid Bed Coater with a Wurster Insert

Science.gov (United States)

de Souza, Luciane Franquelin Gomes; Nitz, Marcello; Taranto, Osvaldir Pereira

2014-01-01

The objective of this work was to study the coating process of nifedipine extended release pellets using Opadry and Opadry II, in a fluid bed coater with a Wurster insert. The coating process was studied using a complete experimental design of two factors at two levels for each polymer. The variables studied were the inlet air temperature and the coating suspension flow rate. The agglomerate fraction and coating efficiency were the analyzed response variables. The air temperature was the variable that most influenced the coating efficiency for both polymers. In addition, a study of the dissolution profiles of coated and uncoated pellets using 0.5% sodium lauryl sulfate in simulated gastric fluid without enzymes (pH 1.2) was conducted. The results showed a prolonged release profile for the coated and uncoated pellets that was very similar to the standards established by the U.S. Pharmacopoeia. The drug content and the release profiles were not significantly affected by storage at 40°C and 75% relative humidity. However, when exposed to direct sunlight and fluorescent light (light from fluorescent bulbs), the coated pellets lost only 5% of the drug content, while the uncoated ones lost more than 35%; furthermore, the dissolution profile of the uncoated pellets was faster. PMID:24772426

Conversion of metallurgical coke and coal using a Coal Direct Chemical Looping (CDCL) moving bed reactor

International Nuclear Information System (INIS)

Luo, Siwei; Bayham, Samuel; Zeng, Liang; McGiveron, Omar; Chung, Elena; Majumder, Ankita; Fan, Liang-Shih

2014-01-01

Highlights: • Accumulated more than 300 operation hours were accomplished for the moving bed reducer reactor. • Different reactor operation variables were investigated with optimal conditions identified. • High conversions of sub-bituminous coal and bituminous coal were achieved without flow problems. • Co-current and counter-current contact modes were tested and their applicability was discussed. - Abstract: The CLC process has the potential to be a transformative commercial technology for a carbon-constrained economy. The Ohio State University Coal Direct Chemical Looping (CDCL) process directly converts coal, eliminating the need for a coal gasifier oran air separation unit (ASU). Compared to other solid-fuel CLC processes, the CDCL process is unique in that it consists of a countercurrent moving bed reducer reactor. In the proposed process, coal is injected into the middle of the moving bed, whereby the coal quickly heats up and devolatilizes, splitting the reactor roughly into two sections with no axial mixing. The top section consists of gaseous fuel produced from the coal volatiles, and the bottom section consists of the coal char mixed with the oxygen carrier. A bench-scale moving bed reactor was used to study the coal conversion with CO 2 as the enhancing gas. Initial tests using metallurgical cokefines as feedstock were conducted to test the effects of operational variables in the bottom section of the moving bed reducer, e.g., reactor temperature, oxygen carrier to char ratio, enhancer gas CO 2 flow rate, and oxygen carrier flow rates. Experiments directly using coal as the feedstock were subsequently carried out based on these test results. Powder River Basin (PRB) coal and Illinois #6 coal were tested as representative sub-bituminous and bituminous coals, respectively. Nearly complete coal conversion was achieved using composite iron oxide particles as the oxygen carriers without any flow problems. The operational results demonstrated that a

Mechanochemical pattern formation in simple models of active viscoelastic fluids and solids

Science.gov (United States)

Alonso, Sergio; Radszuweit, Markus; Engel, Harald; Bär, Markus

2017-11-01

The cytoskeleton of the organism Physarum polycephalum is a prominent example of a complex active viscoelastic material wherein stresses induce flows along the organism as a result of the action of molecular motors and their regulation by calcium ions. Experiments in Physarum polycephalum have revealed a rich variety of mechanochemical patterns including standing, traveling and rotating waves that arise from instabilities of spatially homogeneous states without gradients in stresses and resulting flows. Herein, we investigate simple models where an active stress induced by molecular motors is coupled to a model describing the passive viscoelastic properties of the cellular material. Specifically, two models for viscoelastic fluids (Maxwell and Jeffrey model) and two models for viscoelastic solids (Kelvin-Voigt and Standard model) are investigated. Our focus is on the analysis of the conditions that cause destabilization of spatially homogeneous states and the related onset of mechano-chemical waves and patterns. We carry out linear stability analyses and numerical simulations in one spatial dimension for different models. In general, sufficiently strong activity leads to waves and patterns. The primary instability is stationary for all active fluids considered, whereas all active solids have an oscillatory primary instability. All instabilities found are of long-wavelength nature reflecting the conservation of the total calcium concentration in the models studied.

Advanced treatment of biologically pretreated coal chemical industry wastewater using the catalytic ozonation process combined with a gas-liquid-solid internal circulating fluidized bed reactor.

Science.gov (United States)

Li, Zhipeng; Liu, Feng; You, Hong; Ding, Yi; Yao, Jie; Jin, Chao

2018-04-01

This paper investigated the performance of the combined system of catalytic ozonation and the gas-liquid-solid internal circulating fluidized bed reactor for the advanced treatment of biologically pretreated coal chemical industry wastewater (CCIW). The results indicated that with ozonation alone for 60min, the removal efficiency of chemical oxygen demand (COD) could reach 34%. The introduction of activated carbon, pumice, γ-Al 2 O 3 carriers improved the removal performance of COD, and the removal efficiency was increased by 8.6%, 4.2%, 2%, respectively. Supported with Mn, the catalytic performance of activated carbon and γ-Al 2 O 3 were improved significantly with COD removal efficiencies of 46.5% and 41.3%, respectively; however, the promotion effect of pumice supported with Mn was insignificant. Activated carbon supported with Mn had the best catalytic performance. The catalytic ozonation combined system of MnO X /activated carbon could keep ozone concentration at a lower level in the liquid phase, and promote the transfer of ozone from the gas phase to the liquid phase to improve ozonation efficiency.

Effect of Heterogeneity in Coal Ash Chemical Composition on the Onset of Conditions Favorable for Agglomeration in Fluid Beds

Directory of Open Access Journals (Sweden)

Aditi B. Khadilkar

2015-11-01

Full Text Available Ash agglomeration issues that arise due to the sticking of slag-wetted, colliding particles have been creating operational difficulties and monetary losses for the fluidized bed combustion (FBC industry. Difficulties have been experienced in the detection of slag-liquid at the low operating temperatures in fluidized bed combustors (FBCs and predicting the agglomeration behavior of fuel. This study aims to study the effect of heterogeneity in ash composition on the detection of slag-liquid in FBCs. It quantifies the slag-liquid amounts at the particle-level, under oxidizing environments, by dividing the bulk fuel into density classes. FactSage™ thermodynamic simulations of each of the particle classes, along with experimental validation of the trends with thermo-mechanical analysis (TMA and high temperature X-ray diffraction (HT-XRD were performed. The results obtained can be used to estimate the stickiness of particles in the development of ash agglomeration models based on particle collisions. The study of these particle classes shows that particle classes with specific minerals can form low temperature eutectics and lead to onset of slag-liquid formation at temperatures below those predicted by bulk analysis alone. Comparison of the differences in slag-liquid formation tendencies under reducing and oxidizing environments is also presented.

Effect temperature of supercritical CO2 fluid extraction on phytochemical analysis and antioxidant activity of Zingiber officinale Roscoe

Science.gov (United States)

Sondari, Dewi; Irawadi, Tun Tedja; Setyaningsih, Dwi; Tursiloadi, Silvester

2017-11-01

Supercritical fluid extraction of Zingiber officinale Roscoe has been carried out at a pressure of 16 MPa, with temperatures between 20-40 °C, during extraction time of 6 hours and the flow rate of CO2 fluid 5.5 ml/min. The result of supercritical method was compared with the extraction maceration using a mixture of water and ethanol (70% v/v) for 24 hours. The main content in ginger that has a main role as an antioxidant is a gingerol compound that can help neutralize the damaging effects caused by free radicals in the body, as anti-coagulant, and inhibit the occurrence of blood clots. This study aims to determine the effect of temperature on chemical components contained in rough extract of Zingiber officinale Roscoe and its antioxidant activity, total phenol and total flavonoid content. To determine the chemical components contained in the crude extract of Zingiber officinale Roscoe extracted by supercritical fluid and maceration extraction, GC-MS analysis was performed. Meanwhile, the antioxidant activity of the extract was evaluated based on a 2.2-diphenyl-1-picrylhydrazyl (DPPH) free radical damping method. The results of the analysis show that the result of ginger extract by using the supercritical CO2 extraction method has high antioxidant activity than by using maceration method. The highest total phenol content and total flavonoids were obtained on ginger extraction using supercritical CO2 fluid extraction, indicating that phenol and flavonoid compounds contribute to antioxidant activity. Chromatographic analysis showed that the chemical profile of ginger extract containing oxygenated monoterpenes, monoterpene hydrocarbons, sesquiterpene hydrocarbons, oxygenated monoterpene gingerol and esters. In supercritical fluid extraction, the compounds that can be identified at a temperature of 20-40 °C contain 27 compounds, and 11 compounds from the result of maceration extract. The main component of Zingiber officinale Roscoe extracted using supercritical fluid

Vestibular brain changes within 70 days of head down bed rest.

Science.gov (United States)

Yuan, Peng; Koppelmans, Vincent; Reuter-Lorenz, Patricia; De Dios, Yiri; Gadd, Nichole; Wood, Scott; Riascos, Roy; Kofman, Igor; Bloomberg, Jacob; Mulavara, Ajitkumar; Seidler, Rachael

2018-03-12

Head-down-tilt bed rest (HDBR) is frequently utilized as a spaceflight analog research environment to study the effects of axial body unloading and fluid shifts that are associated with spaceflight in the absence of gravitational modifications. HDBR has been shown to result in balance changes, presumably due to sensory reweighting and adaptation processes. Here, we examined whether HDBR results in changes in the neural correlates of vestibular processing. Thirteen men participated in a 70-day HDBR intervention; we measured balance, functional mobility, and functional brain activity in response to vestibular stimulation at 7 time points before, during, and after HDBR. Vestibular stimulation was administered by means of skull taps, resulting in activation of the vestibular cortex and deactivation of the cerebellar, motor, and somatosensory cortices. Activation in the bilateral insular cortex, part of the vestibular network, gradually increased across the course of HDBR, suggesting an upregulation of vestibular inputs in response to the reduced somatosensory inputs experienced during bed rest. Furthermore, greater increase of activation in multiple frontal, parietal, and occipital regions in response to vestibular stimulation during HDBR was associated with greater decrements in balance and mobility from before to after HDBR, suggesting reduced neural efficiency. These findings shed light on neuroplastic changes occurring with conditions of altered sensory inputs, and reveal the potential for central vestibular-somatosensory convergence and reweighting with bed rest. © 2018 Wiley Periodicals, Inc.

Improved lignin pyrolysis for phenolics production in a bubbling bed reactor--Effect of bed materials.

Science.gov (United States)

Li, Dongbing; Briens, Cedric; Berruti, Franco

2015-01-01

Lignin pyrolysis was studied in a bubbling fluidized bed reactor equipped with a fractional condensation train, using nitrogen as the fluidization gas. The effect of different bed materials (silica sand, lignin char, activated lignin char, birch bark char, and foamed glass beads) on bio-oil yield and quality was investigated for a pyrolysis temperature of 550 °C. Results how that a bed of activated lignin char is preferable to the commonly used silica sand: pyrolysis of Kraft lignin with a bed of activated lignin char not only provides a pure char product, but also a higher dry bio-oil yield (with a relative increase of 43%), lower pyrolytic water production, and better bio-oil quality. The bio-oil obtained from Kraft lignin pyrolysis with a bed of activated lignin char has a lower average molecular weight, less tar, more phenolics, and less acidity than when sand is used as bed material. Copyright © 2015 Elsevier Ltd. All rights reserved.

The composition-explicit distillation curve technique: Relating chemical analysis and physical properties of complex fluids.

Science.gov (United States)

Bruno, Thomas J; Ott, Lisa S; Lovestead, Tara M; Huber, Marcia L

2010-04-16

The analysis of complex fluids such as crude oils, fuels, vegetable oils and mixed waste streams poses significant challenges arising primarily from the multiplicity of components, the different properties of the components (polarity, polarizability, etc.) and matrix properties. We have recently introduced an analytical strategy that simplifies many of these analyses, and provides the added potential of linking compositional information with physical property information. This aspect can be used to facilitate equation of state development for the complex fluids. In addition to chemical characterization, the approach provides the ability to calculate thermodynamic properties for such complex heterogeneous streams. The technique is based on the advanced distillation curve (ADC) metrology, which separates a complex fluid by distillation into fractions that are sampled, and for which thermodynamically consistent temperatures are measured at atmospheric pressure. The collected sample fractions can be analyzed by any method that is appropriate. The analytical methods we have applied include gas chromatography (with flame ionization, mass spectrometric and sulfur chemiluminescence detection), thin layer chromatography, FTIR, corrosivity analysis, neutron activation analysis and cold neutron prompt gamma activation analysis. By far, the most widely used analytical technique we have used with the ADC is gas chromatography. This has enabled us to study finished fuels (gasoline, diesel fuels, aviation fuels, rocket propellants), crude oils (including a crude oil made from swine manure) and waste oils streams (used automotive and transformer oils). In this special issue of the Journal of Chromatography, specifically dedicated to extraction technologies, we describe the essential features of the advanced distillation curve metrology as an analytical strategy for complex fluids. Published by Elsevier B.V.

Enhanced Geothermal Systems Research and Development: Models of Subsurface Chemical Processes Affecting Fluid Flow

Energy Technology Data Exchange (ETDEWEB)

Moller, Nancy; Weare J. H.

2008-05-29

Successful exploitation of the vast amount of heat stored beneath the earth’s surface in hydrothermal and fluid-limited, low permeability geothermal resources would greatly expand the Nation’s domestic energy inventory and thereby promote a more secure energy supply, a stronger economy and a cleaner environment. However, a major factor limiting the expanded development of current hydrothermal resources as well as the production of enhanced geothermal systems (EGS) is insufficient knowledge about the chemical processes controlling subsurface fluid flow. With funding from past grants from the DOE geothermal program and other agencies, we successfully developed advanced equation of state (EOS) and simulation technologies that accurately describe the chemistry of geothermal reservoirs and energy production processes via their free energies for wide XTP ranges. Using the specific interaction equations of Pitzer, we showed that our TEQUIL chemical models can correctly simulate behavior (e.g., mineral scaling and saturation ratios, gas break out, brine mixing effects, down hole temperatures and fluid chemical composition, spent brine incompatibilities) within the compositional range (Na-K-Ca-Cl-SO4-CO3-H2O-SiO2-CO2(g)) and temperature range (T < 350°C) associated with many current geothermal energy production sites that produce brines with temperatures below the critical point of water. The goal of research carried out under DOE grant DE-FG36-04GO14300 (10/1/2004-12/31/2007) was to expand the compositional range of our Pitzer-based TEQUIL fluid/rock interaction models to include the important aluminum and silica interactions (T < 350°C). Aluminum is the third most abundant element in the earth’s crust; and, as a constituent of aluminosilicate minerals, it is found in two thirds of the minerals in the earth’s crust. The ability to accurately characterize effects of temperature, fluid mixing and interactions between major rock-forming minerals and hydrothermal and

Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

Directory of Open Access Journals (Sweden)

Syed Farman Ali Shah

2015-12-01

Full Text Available The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO, granulated activated carbon (GAC bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO4-lime influenced reduction of COD, color, turbidity and TSS by 32%, 48%, 50% and 51%, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88%, 92%, 67% and89%, respectively.

Waste Water Treatment-Bed of Coal Fly Ash for Dyes and Pigments Industry

International Nuclear Information System (INIS)

Shah, S.F.A.; Aftab, A.; Soomro, N.; Nawaz, M.S.; Vafai, K.

2015-01-01

The highly porous power plant waste ashes have been utilized to treat toxic effluent of a dyes manufacturing plant. An attempt has been made for the first time in Pakistan, to generate an effective and economically sound treatment facility for the toxic effluent of a dyes manufacturing plant. This is an indigenous bed which could replace expensive treatment facilities, such as reverse osmosis (RO), granulated activated carbon (GAC) bed, etc. The treatment efficiency was improved by coupling coagulants with fly ash adsorbent bed. The ash was collected from coal fired boilers of power plant at Lakhra Power Generation Company, Jamshoro, Pakistan. The use of this ash resolved the disposal and environmental issues by treating wastewater of chemical, dyes and pigment industry. The treatment bed comprised of briquettes of coal fly ash coupled with commercial coagulant ferrous sulfate-lime reduced COD, color, turbidity and TSS of effluent remarkably. An adsorption capacity and chemical behavior of fly ash bed was also studied. In coagulation treatment, coagulant FeSO/sun 4/-lime influenced reduction of COD, color, turbidity and TSS by 32 percentage, 48 percentage, 50 percentage and 51 percentage, respectively. The CFAB coupled with coagulant, resulted an excessive removal of color, TSS, COD, and turbidity by 88 percentage, 92 percentage, 67 percentage and 89 percentage, respectively. (author)

The complete information for phenomenal distributed parameter control of multicomponent chemical processes in gas, fluid and solid phase

International Nuclear Information System (INIS)

Niemiec, W.

1985-01-01

A constitutive mathematical model of distributed parameters of multicomponent chemical processes in gas, fluid and solid phase is utilized to the realization of phenomenal distributed parameter control of these processes. Original systems of partial differential constitutive state equations, in the following derivative forms /I/, /II/ and /III/ are solved in this paper from the point of view of information for phenomenal distributed parameter control of considered processes. Obtained in this way for multicomponent chemical processes in gas, fluid and solid phase: -dynamical working space-time characteristics/analytical solutions in working space-time of chemical reactors/, -dynamical phenomenal Green functions as working space-time transfer functions, -statical working space characteristics /analytical solutions in working space of chemical reactors/, -statical phenomenal Green functions as working space transfer functions, are applied, as information for realization of constitutive distributed parameter control of mass, energy and momentum aspects of above processes. Two cases are considered by existence of: A/sup o/ - initial conditions, B/sup o/ - initial and boundary conditions, for multicomponent chemical processes in gas, fluid and solid phase

Computational thermal, chemical, fluid, and solid mechanics for geosystems management.

Energy Technology Data Exchange (ETDEWEB)

Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu

2011-09-01

This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.

Instabilities in vertically vibrated fluid-grain systems.

Science.gov (United States)

King, P J; Lopez-Alcaraz, P; Pacheco-Martinez, H A; Clement, C P; Smith, A J; Swift, M R

2007-03-01

When a bed of fluid-immersed fine grains is exposed to vertical vibration a wealth of phenomena may be observed. At low frequencies a horizontal bed geometry is generally unstable and the bed breaks spatial symmetry, acquiring a tilt. At the same time it undergoes asymmetric granular convection. Fine binary mixtures may separate completely into layers or patterns of stripes. The separated regions may exhibit instabilities in which they undergo wave-like motion or exhibit quasi-periodic oscillations. We briefly review these and a number of related behaviours, identifying the physical mechanisms behind each. Finally, we discuss the magneto-vibratory separation of binary mixtures which results from exposing each component to a different effective gravity and describe the influence of a background fluid on this process.

Computational study of fluid flow and heat transfer in composite packed beds of spheres with low tube to particle diameter ratio

International Nuclear Information System (INIS)

Yang, Jian; Wu, Jiangquan; Zhou, Lang; Wang, Qiuwang

2016-01-01

Highlights: • Flow and heat transfer in composite packed beds with low d_t/d_p_e are investigated. • The wall effect would be restrained with radially layered composite packing (RLM). • Heat flux and overall heat transfer efficiency can be improved with RLM packing. - Abstract: The effect of the tube wall on the fluid flow and heat transfer would be important in the packed bed with low tube to particle diameter ratio, which may lead to flow and temperature maldistributions inside, and the heat transfer performance may be lowered. In the present paper, the flow and heat transfer performances in both the composite and uniform packed beds of spheres with low tube to particle diameter were numerically investigated, where the composite packing means randomly packing with non-uniform spheres and the uniform packing means randomly packing with uniform spheres, including radially layered composite packing (RLM), axially layered composite packing (ALM), randomly composite packing (RCM) and randomly uniform packing (RPM). Both the composite and uniform packings were generated with discrete element method (DEM), and the influence of the wall effect on the flow and heat transfer in the packed beds were carefully studied and compared with each other. Firstly, it is found that, the wall effect on the velocity and temperature distributions in the randomly packed bed of uniform spheres (RPM) with low tube to particle diameter ratio were obvious. The average velocity of the near-tube-wall region is higher than that of the inner-tube region in the bed. When the tube wall is adiabatic, the average temperature of the near-tube-wall region is lower. With radially layered composite packing method (RLM), smaller pores would be formed close to the tube wall and big flow channels would be formed in the inner-tube region of the bed, which would be benefit to restrain the wall effect and improve heat transfer in the bed with low tube to particle diameter ratio. Furthermore, it is also

Computational study of fluid flow and heat transfer in composite packed beds of spheres with low tube to particle diameter ratio

Energy Technology Data Exchange (ETDEWEB)

Yang, Jian, E-mail: yangjian81@mail.xjtu.edu.cn [Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Wu, Jiangquan [CSR Research of Electrical Technology and Material Engineering, Zhuzhou, Hunan 412001 (China); Zhou, Lang; Wang, Qiuwang [Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China)

2016-04-15

Highlights: • Flow and heat transfer in composite packed beds with low d{sub t}/d{sub pe} are investigated. • The wall effect would be restrained with radially layered composite packing (RLM). • Heat flux and overall heat transfer efficiency can be improved with RLM packing. - Abstract: The effect of the tube wall on the fluid flow and heat transfer would be important in the packed bed with low tube to particle diameter ratio, which may lead to flow and temperature maldistributions inside, and the heat transfer performance may be lowered. In the present paper, the flow and heat transfer performances in both the composite and uniform packed beds of spheres with low tube to particle diameter were numerically investigated, where the composite packing means randomly packing with non-uniform spheres and the uniform packing means randomly packing with uniform spheres, including radially layered composite packing (RLM), axially layered composite packing (ALM), randomly composite packing (RCM) and randomly uniform packing (RPM). Both the composite and uniform packings were generated with discrete element method (DEM), and the influence of the wall effect on the flow and heat transfer in the packed beds were carefully studied and compared with each other. Firstly, it is found that, the wall effect on the velocity and temperature distributions in the randomly packed bed of uniform spheres (RPM) with low tube to particle diameter ratio were obvious. The average velocity of the near-tube-wall region is higher than that of the inner-tube region in the bed. When the tube wall is adiabatic, the average temperature of the near-tube-wall region is lower. With radially layered composite packing method (RLM), smaller pores would be formed close to the tube wall and big flow channels would be formed in the inner-tube region of the bed, which would be benefit to restrain the wall effect and improve heat transfer in the bed with low tube to particle diameter ratio. Furthermore, it

Chemical Characterization of Bed Material Coatingsby LA-ICP-MS and SEM-EDS

Science.gov (United States)

Piispanen, M. H.; Mustonen, A. J.; Tiainen, M. S.; Laitinen, R. S.

Bed material coatings and the consequent agglomeration of bed material are main ash-related problems in FB-boilers. The bed agglomeration is a particular problem when combusting biofuels and waste materials. Whereas SEM-EDS together with automated image processing has proven to be a convenient method to study compositional distribution in coating layers and agglomerates, it is a relatively expensive technique and is not necessarily widely available. In this contribution, we explore the suitability of LA-ICP-MS to provide analogous information of the bed.

Performances of continuous dryer with inert medium fluidized bed

Directory of Open Access Journals (Sweden)

Arsenijević Zorana Lj.

2008-01-01

Full Text Available A fluid bed dryer with inert particles represents a very attractive alternative to other drying technologies according to the main efficiency criteria, i.e. specific water evaporation rate, specific heat consumption and speci­fic air consumption. A high drying efficiency results from the large con­tact area and from the large temperature difference between the inlet and outlet air. A rapid mixing of the particles leads to nearly isothermal conditions throughout the bed. A fluid bed dryer with inert particles was used for drying of slurries. Experiments were performed in a cylindrical column 215 mm in diameter with glass spheres as inert particles. In this paper, results of drying experi­ments with slurries of Zineb fungicide, copper hydroxide, calcium carbo­nate and pure water used as the feed material are presented. In our fluidized bed we successfully dried a number of other materials such as: fungicides and pesticides (Ziram, Propineb, Mangozeb, copper oxy-chloride, copper oxy-sulphate, Bordeaux mixture, other inorganic compounds (calcium sulphate, cobalt carbonate, electrolytic copper, sodium chloride, and a complex compound (organo-bentonite. The effects of operating conditions on dryer throughput and product quality were investigated. Main performance criteria, i.e. specific water evaporation rate, specific heat consumption and specific air consumption, were quantified. Temperature profile along the bed was mapped, and nearly isothermal conditions were found due to thorough mixing of the particles. Analysis of drying and energy efficiencies as a function of inlet and outlet air temperature difference was performed for deeper insight in dryer behavior and for optimizing dryer design and operation from an energy point of view. A simple mathematical model based on an overall heat balance predicts the dryer performance quite well. The industrial prototype with fluid bed of 0.8 m in diameter and capacity 650 kg of evaporated moisture per

Characterization and evaluation in vivo of baicalin-nanocrystals prepared by an ultrasonic-homogenization-fluid bed drying method.

Science.gov (United States)

Shi-Ying, Jin; Jin, Han; Shi-Xiao, Jin; Qing-Yuan, Lv; Jin-Xia, Bai; Chen, Hong-Ge; Rui-Sheng, Li; Wei, Wu; Hai-Long, Yuan

2014-01-01

To improve the absorption and bioavailability of baicalin using a nanocrystal (or nanosuspension) drug delivery system. A tandem, ultrasonic-homogenization-fluid bed drying technology was applied to prepare baicalin-nanocrystal dried powders, and the physicochemical properties of baicalin-nanocrystals were characterized by scanning electron microscopy, photon correlation spectroscopy, powder X-ray diffraction, physical stability, and solubility experiments. Furthermore, in situ intestine single-pass perfusion experiments and pharmacokinetics in rats were performed to make a comparison between the microcrystals of baicalin and pure baicalin in their absorption properties and bioavailability in vivo. The mean particle size of baicalin-nanocrystals was 236 nm, with a polydispersity index of 0.173, and a zeta potential value of -34.8 mV, which provided a guarantee for the stability of the reconstituted nanosuspension. X-Ray diffraction results indicated that the crystallinity of baicalin was decreased through the ultrasonic-homogenization process. Physical stability experiments showed that the prepared baicalin-nanocrystals were sufficiently stable. It was shown that the solubility of baicalin in the form of nanocrystals, at 495 μg·mL(-1), was much higher than the baicalin-microcrystals and the physical mixture (135 and 86.4 μg·mL(-1), respectively). In situ intestine perfusion experiments demonstrated a clear advantage in the dissolution and absorption characteristics for baicalin-nanocrystals compared to the other formulations. In addition, after oral administration to rats, the particle size decrease from the micron to nanometer range exhibited much higher in vivo bioavailability (with the AUC(0-t) value of 206.96 ± 21.23 and 127.95 ± 14.41 mg·L(-1)·h(-1), respectively). The nanocrystal drug delivery system using an ultrasonic-homogenization-fluid bed drying process is able to improve the absorption and in vivo bioavailability of baicalin, compared with pure

On the solid stress in a fluidized bed

International Nuclear Information System (INIS)

Qassim, R.Y.; Souza, R. de.

1980-09-01

The existence of solid stress in an incipiently gas-fluidized bed is shown by experimental measurement. This stress is shown to have two components: an isotropic pressure and an extra stress which depends on the relative velocity between fluid and solid. Both the solid pressure and the solid extra stress component are found to be of the same order of magnitude as the fluid pressure. (Author) [pt

CFD study on the supercritical carbon dioxide cooled pebble bed reactor

Energy Technology Data Exchange (ETDEWEB)

Yu, Dali, E-mail: ydlmitd@outlook.com; Peng, Minjun; Wang, Zhongyi

2015-01-15

Highlights: • An innovation concept of supercritical carbon dioxide cooled pebble bed reactor is proposed. • Body-centered cuboid (BCCa) arrangement is adopted for the pebbles. • S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor. - Abstract: The thermal hydraulic study of using supercritical carbon dioxide (S-CO{sub 2}), a superior fluid state brayton cycle medium, in pebble bed type nuclear reactor is assessed through computational fluid dynamics (CFD) methodology. Preliminary concept design of this S-CO{sub 2} cooled pebble bed reactor (PBR) is implemented by the well-known KTA heat transfer correlation and Ergun pressure drop equation. Eddy viscosity transport turbulence model is adopted and verified by KTA calculated results. Distributions of the temperature, velocity, pressure and Nusselt (Nu) number of the coolant near the surface of the middle spherical fuel element are obtained and analyzed. The conclusion of the assessment is that S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor due primarily to its good heat transfer characteristic and large mass density, which could lead to achieve lower pressure drop and higher power density.

Review of PSI studies on reactor physics and thermal fluid dynamics of pebble bed reactors

International Nuclear Information System (INIS)

Prasser, Horst-Michael

2014-01-01

Switzerland is member of the Generation IV International Forum (GIF). The related work takes entirely place at PSI in the working groups of Gas-Cooled Fast Reactors and Very High Temperature Reactors. In the past, PSI has performed experimental and theoretical studies on criticality issues of pebble beds at the PROTEUS reactor, as well as a preliminary risk assessment of a prototypal HTR as an input for a comparison of energy supply options. PROTEUS was a critical assembly with an annular driver zone. The central region was filled by arrangements of fuel spheres. The reactivity effect of a water ingress was investigated by simulating the water by polyethylene rods of different diameter inserted into the gaps of a regular package. For sub-criticality measurements in pebble beds, a built-in pulsed neutron source was used. The experimental results were used to validate diffusion and higher order neutron transport models. Concerning thermal hydraulics of gas flows, the vast experience of PSI is focused on hydrogen transport, accumulation, and dispersion in containments of light water reactors. The phenomena are comparable in many aspects to the fluid dynamic issues relevant to HTR. Experiments on hydrogen flows are performed for numerous scenarios in the large-scale containment test facility PANDA. Hydrogen is substituted by helium as a model fluid. An important generic aspect is turbulent mixing in the presence of strong stratification, which is relevant for HTR as well. In a parallel project, generic small-scale mixing experiments with a high density ratio of 1:7 are carried out in a horizontal rectangular channel, where helium and nitrogen flows are brought into contact downstream of the rear edge of a splitter plate. Due to the high density ratio, turbulent mixing is affected by strong non-Boussinesq effects. The measurements taken by Particle Imaging Velocimetry (PIV) and Laser Induced Fluorescence techniques are compared to RANS and LES simulations. Similar large

CFD-DEM simulation of a conceptual gas-cooled fluidized bed nuclear reactor

International Nuclear Information System (INIS)

Almeida, Lucilla C.; Su, Jian

2015-01-01

Several conceptual designs of the fluidized-bed nuclear reactor have been proposed due to its many advantages over conventional nuclear reactors such as PWRs and BWRs. Amongst their characteristics, the enhanced heat transfer and mixing enables a more uniform temperature distribution, reducing the risk of hot-spot and excessive fuel temperature, in addition to resulting in a higher burnup of the fuel. Furthermore, the relationship between the bed height and reactor neutronics turns the coolant flow rate control into a power production mechanism. Moreover, the possibility of removing the fuel by gravity from the movable core in case of a loss-of-cooling accident increases its safety. High-accuracy modeling of particles and coolant flow in fluidized bed reactors is needed to evaluate reliably the thermal-hydraulic efficiency and safety margin. The two-way coupling between solid and fluid can account for high-fidelity solid-solid interaction and reasonable accuracy in fluid calculation and fluid-solid interaction. In the CFD-DEM model, the particles are modeled as a discrete phase, following the DEM approach, whereas the fluid flow is treated as a continuous phase, described by the averaged Navier-Stokes equations on a computational cell scale. In this work, the coupling methodology between Fluent and Rocky is described. The numerical approach was applied to the simulation of a bubbling fluidized bed and the results were compared to experimental data and showed good agreement. (author)

Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies

International Nuclear Information System (INIS)

Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

2016-01-01

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m"2/g), high pore volume (1.23 cm"3/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution. - Highlights: • A high efficiency adsorbent for sulfonamide removal is prepared from anthracite. • Effects of

Physiology Of Prolonged Bed Rest

Science.gov (United States)

Greenleaf, John E.

1991-01-01

Report describes physiological effects of prolonged bed rest. Rest for periods of 24 hours or longer deconditions body to some extent; healing proceeds simultaneously with deconditioning. Report provides details on shifts in fluid electrolytes and loss of lean body mass, which comprises everything in body besides fat - that is, water, muscle, and bone. Based on published research.

The processing of bed ashes of fluidized bed boilers to an applicable ingredient for building materials. Het bewerken van bedassen van wervelbedketels tot een geschikte grondstof voor toepassing in bouwprodukten

Energy Technology Data Exchange (ETDEWEB)

Dekker, W

1988-01-01

A study- and test program has been carried out to determine in what way bed ashes of fluidized bed boilers can be processed to applicate the products in building products. The program consisted of selecting applicable ashes; physical-chemical research; slack lime, present in the ashes; grinding and wind-sifting of the ashes; evaluation of the quality of the acquired samples for application in calcium-silicate brick and in mortar; the making of flow-sheets of the processing in the potential demonstration projects. The used sample was a bed ash with active CaO content of 21%. Conclusions were stated and recommendations were made. 6 figs., 6 refs., 9 tabs., 2 app.

Influence of heat and chemical reactions on the Sisko fluid model for ...

African Journals Online (AJOL)

The present article studies the effects of heat and chemical reactions on the blood flow through tapered artery with a stenosis. The model incorporates Sisko fluid representation for the blood flow through an axially non-symmetrical but radially symmetric stenosis. Symmetry of the distribution of the wall shearing stress and ...

Effects of flow balancing on active magnetic regenerator performance

DEFF Research Database (Denmark)

Eriksen, Dan; Engelbrecht, Kurt; Bahl, Christian

2016-01-01

Experiments with a recently constructed rotary multi-bed active magnetic regnenerator (AMR) prototype have revealed strong impacts on the temperature span from variations in the resistances of the flow channels carrying heat transfer fluid in and out of the regenerator beds. In this paper we show...

Coexistence of solidlike and fluidlike states in a deep gas-fluidized bed

NARCIS (Netherlands)

Wang, J.; Hoef, van der M.A.; Kuipers, J.A.M.

2010-01-01

Characterizing regime transition in gas-fluidized beds is of fundamental importance for the successful applications of fluidization technology. In this study, we show that a state-of-the-art two-fluid model has the ability to correctly predict the transition from packed bed to fully bubbling

Comparison of Ocular Outcomes in Two 14-Day Bed Rest Studies

Science.gov (United States)

Cromwell, R. L.; Zanello, S. B.; Yarbough, P. O.; Taibbi, G.; Vizzeri, G.

2011-01-01

Reports of astronauts visual changes raised concern about ocular health during long-duration spaceflight. Some of these findings included hyperopic shifts, choroidal folds, optic disc edema, retinal nerve fiber layer (RNFL) thickening, and cotton wool spots. While the etiology remains unknown, hypotheses speculate that hypertension in the brain caused by cephalad fluid shifts during spaceflight is a possible mechanism for these ocular changes. Head-down tilt (HDT) bed rest is a spaceflight analog that induces cephalad fluid shifts. In addition, previous studies of the HDT position demonstrated body fluid shifts associated with changes in intraocular pressure (IOP). For these reasons, vision monitoring of HDT bed rest subjects was implemented for NASA bed rest studies. Subjects selected for these studies were healthy adults (14 males and 5 females). Average age was 37.5 plus or minus 9.1 years, weight was 77.4 plus or minus 11.3 Kg, and height was 173.4 plus or minus 7.2 14 cm. Controlled conditions followed for all NASA bed rest studies were implemented. These conditions included factors such as eating a standardized diet, maintaining a strict sleep wake cycle, and remaining in bed for 24 hours each day. In one study, subjects maintained a horizontal (0 degree) position while in bed and were exercised six days per week with an integrated resistance and aerobic training (iRAT) program. In the other study, subjects were placed at 6 degrees HDT while in bed and did not engage in exercise. All subjects underwent pre- and post bed rest vision testing. While the battery of vision tests for each study was not identical, measures common to both studies will be presented. These measures included IOP and measures that provided an indication of optic disc swelling as derived from optical coherence tomography (OCT) testing: average retinal nerve fiber layer (RNFL) thickness (millimeters), disc area (square millimeters), rim area (square millimters), and average cup to disc (C

The influence of bamboo-packed configuration to mixing characteristics in a fixed-bed reactor

Science.gov (United States)

Detalina, M.; Pradanawati, S. A.; Widyarani; Mamat; Nilawati, D.; Sintawardani, N.

2018-03-01

Fixed-bed reactors are commonly used as bioreactors for various applications, including chemicals production and organic wastewater treatment. Bioreactors are fixed with packing materials for attaching microorganisms. Packing materials should have high surface area and enable sufficient fluid flow in the reactor. Natural materials e.g. rocks and fibres are often used as packing materials. Commercially, packing materials are also produced from polymer with the advantage of customizable shapes. The objective of this research was to study the mixing pattern in a packed-bed reactor using bamboo as packing material. Bamboo was selected for its pipe-like and porous form, as well as its abundant availability in Indonesia. The cut bamboo sticks were installed in a reactor in different configurations namely vertical, horizontal, and random. Textile dye was used as a tracer. Our results show that the vertical configuration gave the least liquid resistant flow. Yet, the random configuration was the best configuration during mixing process.

Transient Catalytic Activity of Calcined Dolomitic Limestone in a Fluidized Bed during Gasification of Woody Biomass.

Czech Academy of Sciences Publication Activity Database

Pohořelý, Michael; Jeremiáš, Michal; Skoblia, S.; Beňo, Z.; Šyc, Michal; Svoboda, Karel

2016-01-01

Roč. 30, č. 5 (2016), s. 4065-4071 ISSN 0887-0624 R&D Projects: GA ČR GC14-09692J Institutional support: RVO:67985858 Keywords : fluidized- bed gasification * woody biomass * limestone Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.091, year: 2016

Agglomeration of bed material: Influence on efficiency of biofuel fluidized bed boiler

Directory of Open Access Journals (Sweden)

Ryabov Georgy A.

2003-01-01

Full Text Available The successful design and operation of a fluidized bed combustor requires the ability to control and mitigate ash-related problems. The main ash-related problem of biomass filing boiler is agglomeration. The fluidized bed boiler with steam capacity of 66 t/h (4 MPa, 440 °C was started up at the Arkhangelsk Paper-Pi dp-Plant in 2001. This boiler was manufactured by the Russian companies "Energosofin" and "Belenergomash" and installed instead of the existing boiler with mechanical grate. Some constructional elements and steam drum of existing boiler remained unchanged. The primary air fan was installed past the common air fan, which supply part of the air into 24 secondary airports. First operating period shows that the bed material is expanded and then operator should increase the primary air rate, and the boiler efficiency dramatically decreases. Tills paper presents some results of our investigations of fuel, bed and fly ash chemical compositions and other characteristics. Special experiments were carried out to optimize the bed drain flow rate. The influence of secondly air supply improvement on mixing with the main flow and boiler efficiency are given.

Importance of spinel reaction kinetics in packed-bed chemical looping combustion using a CuO/Al2O3 oxygen carrier

NARCIS (Netherlands)

San Pio, M.A.; Sabatino, F.; Gallucci, F.; van Sint Annaland, M.

2018-01-01

Chemical looping combustion is especially competitive for electrical power generation with integrated CO2 capture when it is operated at high temperatures (1000–1200 °C) and high pressures (15 bar or higher). For these demanding conditions, dynamically operated packed bed reactors have been

Experimental Study of the Flooding and Appearance of a Bubble Bed on Top of a Countercurrent Packed-Bed Column

Czech Academy of Sciences Publication Activity Database

Jiřičný, Vladimír; Staněk, Vladimír; Svoboda, Petr; Ondráček, Jakub

2001-01-01

Roč. 40, č. 1 (2001), s. 407-412 ISSN 0888-5885 R&D Projects: GA ČR GA203/97/1174 Institutional research plan: CEZ:AV0Z4072921 Keywords : appearance * bubble-bed * packed bed column Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.351, year: 2001

Sulfate Adsorption on Iron Nanocomposites on Graphene Oxide and Activated Carbon Beds

Directory of Open Access Journals (Sweden)

Rezvan Birooni

2017-01-01

Full Text Available This study is an experimental investigation of sulfate removal efficiency using iron nanocomposites on graphene oxide and activated carbon beds. The graphene oxide used was synthesized according to the Hummer method during which process graphene oxide and activated carbon were added. The effects of various parameters including adsorbent content, pH, and contact time on adsorption were investigated. Furthermore, the data were subjected to kinetic studies. Results revealed that the highest absorption rates of 84% and 62% were achieved for iron on the graphene oxide and activated carbon beds, respectively, when 0.06 g of the adsorbent was used at pH =11 over a contact time of 9 hours. It was also found that the kinetic pseudo-second-order model best fit the data. Finally, the results indicated that the two environmentally-friendly adsorbents have a good potential for removing sulfate from aqueous solutions.

Adsorption of ciprofloxacin and norfloxacin from aqueous solution onto granular activated carbon in fixed bed column.

Science.gov (United States)

Darweesh, Teeba M; Ahmed, Muthanna J

2017-04-01

Carbonization of Phoenix dactylifera L stones followed by microwave K 2 CO 3 activation was adopted for preparation of granular activated carbon (KAC). High yield and favorable pore characteristics in terms of surface area and pore volume were reported for KAC as follows: 44%, 852m 2 /g, and 0.671cm 3 /g, respectively. The application of KAC as adsorbent for attraction of ciprofloxacin (CIP) and norfloxacin (NOR) was investigated using fixed bed systems. The effect of flow rate (0.5-1.5ml/min), bed height (15-25cm), and initial drug concentration (75-225mg/l) on the behavior of breakthrough curves was explained. The fixed bed analysis showed the better correlation of breakthrough data by both Thomas and Yoon-Nelson models. Inlet drug concentration was of greatest effect on breakthrough data compared to other fixed bed variables. Experimental and calculated breakthrough data were obtained for CIP and NOR adsorption on KAC, thus being important for design of fixed bed column. Copyright © 2016 Elsevier Inc. All rights reserved.

Fluidized Bed Steam Reforming For Treatment And Immobilization Of Low-Activity Waste

International Nuclear Information System (INIS)

Hewitt, W.M.

2011-01-01

This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of fluidized bed steam reforming and its possible application to treat and immobilize Hanford low-activity waste.

Acquisition of chemical remanent magnetization during experimental ferrihydrite-hematite conversion in Earth-like magnetic field-implications for paleomagnetic studies of red beds

NARCIS (Netherlands)

Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J.; Tauxe, Lisa; Qin, Huafeng; Barrón, Vidal; Torrent, José

2015-01-01

Hematite-bearing red beds are renowned for their chemical remanent magnetization (CRM). If the CRM was acquired substantially later than the sediment was formed, this severely compromises paleomagnetic records. To improve our interpretation of the natural remanent magnetization, the intricacies of

Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

Energy Technology Data Exchange (ETDEWEB)

Bischi, Aldo

2012-05-15

Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

Long Duration Head-Down Tilt Bed Rest Studies: Safety Considerations Regarding Vision Health

Science.gov (United States)

Cromwell, Ronita L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, Robert; Taibbi, G.; Vizzeri, G.

2012-01-01

Visual symptoms reported in astronauts returning from long duration missions in low Earth orbit, including hyperopic shift, choroidal folds, globe flattening and papilledema, are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, safety considerations have been raised regarding the ocular health of head-down tilt (HDT) bed rest subjects. HDT is a widely used ground ]based analog that simulates physiological changes of spaceflight, including fluid shifts. Thus, vision monitoring has been performed in bed rest subjects in order to evaluate the safety of HDT with respect to vision health. Here we report ocular outcomes in 9 healthy subjects (age range: 27-48 years; Male/Female ratio: 8/1) completing bed rest Campaign 11, an integrated, multidisciplinary 70-day 6 degrees HDT bed rest study. Vision examinations were performed on a weekly basis, and consisted of office-based (2 pre- and 2 post-bed rest) and in-bed testing. The experimental design was a repeated measures design, with measurements for both eyes taken for each subject at each planned time point. Findings for the following tests were all reported as normal in each testing session for every subject: modified Amsler grid, red dot test, confrontational visual fields, color vision and fundus photography. Overall, no statistically significant differences were observed for any of the measures, except for both near and far visual acuity, which increased during the course of the study. This difference is not considered clinically relevant as may result from the effect of learning. Intraocular pressure results suggest a small increase at the beginning of the bed rest phase (p=0.059) and lesser increase at post-bed rest with respect to baseline (p=0.046). These preliminary results provide the basis for further analyses that will include correlations between intraocular pressure change pre- and post-bed rest, and optical coherence

Metabolic Potential and Activity in Fluids of the Coast Range Ophiolite Microbial Observatory, California, USA

Science.gov (United States)

Hoehler, T.; Som, S.; Schrenk, M.; McCollom, T.; Cardace, D.

2016-01-01

Metabolic potential and activity associated with hydrogen and carbon monoxide were characterized in fluids sampled from the the Coast Range Ophiolite Microbial Observatory (CROMO). CROMO consists of two clusters of science-dedicated wells drilled to varying depths up to 35m in the actively serpentinizing, Jurassic-age Coast Range Ophiolite of Northern California, along with a suite of pre-existing monitoring wells at the same site. Consistent with the fluid chemistry observed in other serpentinizing systems, CROMO fluids are highly alkaline, with pH up to 12.5, high in methane, with concentrations up 1600 micromolar, and low in dissolved inorganic carbon (DIC), with concentrations of 10's to 100's of micromolar. CROMO is conspicuous for fluid H2 concentrations that are consistently sub-micromolar, orders of magnitude lower than is typical of other systems. However, higher H2 concentrations (10's -100's of micromolar) at an earlier stage of fluid chemical evolution are predicted by, or consistent with: thermodynamic models for fluid chemistry based on parent rock composition equivalent to local peridotite and with water:rock ratio constrained by observed pH; the presence of magnetite at several wt% in CROMO drill cores; and concentrations of formate and carbon monoxide that would require elevated H2 if formed in equilibrium with H2 and DIC. Calculated Gibbs energy changes for reaction of H2 and CO in each of several metabolisms, across the range of fluid composition encompassed by the CROMO wells, range from bioenergetically feasible (capable of driving ATP synthesis) to thermodynamically unfavorable. Active consumption relative to killed controls was observed for both CO and H2 during incubation of fluids from the pre-existing monitoring wells; in incubations of freshly cored solids, consumption was only observed in one sample set (corresponding to the lowest pH) out of three. The specific metabolisms by which H2 and CO are consumed remain to be determined.

Numerical investigation of the flow at the pebble bed of the high temperature gas cooled reactors

International Nuclear Information System (INIS)

Costa, Franklin C.; Navarro, Moyses A.; Santos, Andre A.C.

2011-01-01

This paper presents a numerical investigation of the thermal and fluid dynamics among the fuel spheres and the cooling fluid, appearing in the core of pebble bed reactor (PBR-Peeble Bed Reactor) using the CFD-Computational Fluid Dynamics CFX 13.0. The paper presents the two analysis results. In the first phase it was considered two heat transfer models for the fuel spheres. In a model it was established volumetric load generation, with thermal conduction for both the fuel and coating. The other model prescribes a heat flux at the sphere surfaces. In this analysis, it was proceed two simulation in the two sphere arrangements, one considering the spheres in contact, and the other with 2 mm spacing between them. At the second analysis it was evaluated the sphere arrangement influence on the thermal and fluid dynamic behavior of the bed. The four simulations present differences in the flow and in the surface and maximum temperature profiles of the coating.(author)

Staged fluidized-bed combustion and filter system

International Nuclear Information System (INIS)

Mei, J.S.; Halow, J.S.

1994-01-01

A staged fluidized-bed combustion and filter system are described for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized-bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gases into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste. 10 figures

FLUIDIZED BED STEAM REFORMING FOR TREATMENT AND IMMOBILIZATION OF LOW-ACTIVITY WASTE

Energy Technology Data Exchange (ETDEWEB)

HEWITT WM

2011-04-08

This report is one of four reports written to provide background information regarding immobilization technologies remaining under consideration for supplemental immobilization of Hanford's low-activity waste. This paper provides the reader a general understanding of fluidized bed steam reforming and its possible application to treat and immobilize Hanford low-activity waste.

Fluid sampling and chemical modeling of geopressured brines containing methane. Final report, March 1980-February 1981

Energy Technology Data Exchange (ETDEWEB)

Dudak, B.; Galbraith, R.; Hansen, L.; Sverjensky, D.; Weres, O.

1982-07-01

The development of a flowthrough sampler capable of obtaining fluid samples from geopressured wells at temperatures up to 400/sup 0/F and pressures up to 20,000 psi is described. The sampler has been designed, fabricated from MP35N alloy, laboratory tested, and used to obtain fluid samples from a geothermal well at The Geysers, California. However, it has not yet been used in a geopressured well. The design features, test results, and operation of this device are described. Alternative sampler designs are also discussed. Another activity was to review the chemistry and geochemistry of geopressured brines and reservoirs, and to evaluate the utility of available computer codes for modeling the chemistry of geopressured brines. The thermodynamic data bases for such codes are usually the limiting factor in their application to geopressured systems, but it was concluded that existing codes can be updated with reasonable effort and can usefully explain and predict the chemical characteristics of geopressured systems, given suitable input data.

Two-dimensional lift-up problem for a rigid porous bed

Energy Technology Data Exchange (ETDEWEB)

Chang, Y.; Huang, L. H.; Yang, F. P. Y. [Department of Civil Engineering, National Taiwan University, Taipei, Taiwan (China)

2015-05-15

The present study analytically reinvestigates the two-dimensional lift-up problem for a rigid porous bed that was studied by Mei, Yeung, and Liu [“Lifting of a large object from a porous seabed,” J. Fluid Mech. 152, 203 (1985)]. Mei, Yeung, and Liu proposed a model that treats the bed as a rigid porous medium and performed relevant experiments. In their model, they assumed the gap flow comes from the periphery of the gap, and there is a shear layer in the porous medium; the flow in the gap is described by adhesion approximation [D. J. Acheson, Elementary Fluid Dynamics (Clarendon, Oxford, 1990), pp. 243-245.] and the pore flow by Darcy’s law, and the slip-flow condition proposed by Beavers and Joseph [“Boundary conditions at a naturally permeable wall,” J. Fluid Mech. 30, 197 (1967)] is applied to the bed interface. In this problem, however, the gap flow initially mainly comes from the porous bed, and the shear layer may not exist. Although later the shear effect becomes important, the empirical slip-flow condition might not physically respond to the shear effect, and the existence of the vertical velocity affects the situation so greatly that the slip-flow condition might not be appropriate. In contrast, the present study proposes a more general model for the problem, applying Stokes flow to the gap, the Brinkman equation to the porous medium, and Song and Huang’s [“Laminar poroelastic media flow,” J. Eng. Mech. 126, 358 (2000)] complete interfacial conditions to the bed interface. The exact solution to the problem is found and fits Mei’s experiments well. The breakout phenomenon is examined for different soil beds, mechanics that cannot be illustrated by Mei’s model are revealed, and the theoretical breakout times obtained using Mei’s model and our model are compared. The results show that the proposed model is more compatible with physics and provides results that are more precise.

Petrology and geochemistry of samples from bed-contact zones in Tunnel Bed 5, U12g-Tunnel, Nevada Test Site

International Nuclear Information System (INIS)

Connolly, J.R.; Keil, K.; Mansker, W.L.; Allen, C.C.; Husler, J.; Lowy, R.; Fortney, D.R.; Lappin, A.R.

1984-10-01

This report summarizes the detailed geologic characterization of samples of bed-contact zones and surrounding nonwelded bedded tuffs, both within Tunnel Bed 5, that are exposed in the G-Tunnel complex beneath Rainier Mesa on the Nevada Test Site (NTS). Original planning studies treated the bed-contact zones in Tunnel Bed 5 as simple planar surfaces of relatively high permeability. Detailed characterization, however, indicates that these zones have a finite thickness, are depositional in origin, vary considerably over short vertical and horizontal distances, and are internally complex. Fluid flow in a sequence of nonwelded zeolitized ash-flow or bedded tuffs and thin intervening reworked zones appears to be a porous-medium phenomenon, regardless of the presence of layering. There are no consistent differences in either bulk composition or detailed mineralogy between bedded tuffs and bed-contact zones in Tunnel Bed 5. Although the original bulk composition of Tunnel Bed 5 was probably peralkaline, extensive zeolitization has resulted in a present peraluminous bulk composition of both bedded tuffs and bed-contact zones. The major zeolite present, clinoptilolite, is intermediate (Ca:K:Na = 26:35:39) and effectively uniform in composition. This composition is similar to that of clinoptilolite from the tuffaceous beds of Calico Hills above the static water level in hole USW G-1, but somewhat different from that reported for zeolites from below the static water level in USW G-2. Tunnel Bed 5 also contains abundant hydrous manganese oxides. The similarity in composition of the clinoptilolites from Tunnel Bed 5 and those above the static water level at Yucca Mountain indicates that many of the results of nuclide-migration experiments in Tunnel Bed 5 would be transferrable to zeolitized nonwelded tuffs above the static water level at Yucca Mountain

Biological fluidized-bed treatment of groundwater from a manufactured gas plant site

International Nuclear Information System (INIS)

Grey, G.M.; Scheible, O.K.; Maiello, J.A.; Guarini, W.J.; Sutton, P.M.

1995-01-01

Bench- and pilot-scale biological treatability studies were performed as part of a comprehensive study for developing an on-site treatment system for contaminated groundwater at a former manufactured gas plant site. The bench-scale work, which included evaluations of activated sludge and fluidized-bed biological processes, indicated that a carbon-based fluidized-bed process was most appropriate. The process was then demonstrated on a pilot level at the site. The bench and pilot studies demonstrated significant reductions of chemical oxygen demand (COD), and all target organics including polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs)

Double stratification effects in chemically reactive squeezed Sutterby fluid flow with thermal radiation and mixed convection

Science.gov (United States)

Ahmad, S.; Farooq, M.; Javed, M.; Anjum, Aisha

2018-03-01

A current analysis is carried out to study theoretically the mixed convection characteristics in squeezing flow of Sutterby fluid in squeezed channel. The constitutive equation of Sutterby model is utilized to characterize the rheology of squeezing phenomenon. Flow characteristics are explored with dual stratification. In flowing fluid which contains heat and mass transport, the first order chemical reaction and radiative heat flux affect the transport phenomenon. The systems of non-linear governing equations have been modulating which then solved by mean of convergent approach (Homotopy Analysis Method). The graphs are reported and illustrated for emerging parameters. Through graphical explanations, drag force, rate of heat and mass transport are conversed for different pertinent parameters. It is found that heat and mass transport rate decays with dominant double stratified parameters and chemical reaction parameter. The present two-dimensional examination is applicable in some of the engineering processes and industrial fluid mechanics.

Exercise Effects on the Course of Gray Matter Changes Over 70 Days of Bed Rest

Science.gov (United States)

Koppelmans, V.; Ploutz-Snyder, L.; DeDios, Y. E.; Wood, S. J.; Reuter-Lorenz, P. A.; Kofman, I.; Bloomberg, J. J.; Mulavara, A. P.; Seidler, R. D.

2014-01-01

Long duration spaceflight affects posture control, locomotion, and manual control. The microgravity environment is an important causal factor for spaceflight induced sensorimotor changes through direct effects on peripheral changes that result from reduced vestibular stimulation and body unloading. Effects of microgravity on sensorimotor function have been investigated on earth using bed rest studies. Long duration bed rest serves as a space-flight analogue because it mimics microgravity in body unloading and bodily fluid shifts. It has been hypothesized that the cephalad fluid shift that has been observed in microgravity could potentially affect central nervous system function and structure, and thereby indirectly affect sensorimotor or cognitive functioning. Preliminary results of one of our ongoing studies indeed showed that 70 days of long duration head down-tilt bed rest results in focal changes in gray matter volume from pre-bed rest to various time points during bed rest. These gray matter changes that could reflect fluid shifts as well as neuroplasticity were related to decrements in motor skills such as maintenance of equilibrium. In consideration of the health and performance of crewmembers both inand post-flight we are currently conducting a study that investigates the potential preventive effects of exercise on gray matter and motor performance changes that we observed over the course of bed rest. Numerous studies have shown beneficial effects of aerobic exercise on brain structure and cognitive performance in healthy and demented subjects over a large age range. We therefore hypothesized that an exercise intervention in bed rest could potentially mitigate or prevent the effects of bed rest on the central nervous system. Here we present preliminary outcomes of our study.

A quality by design study applied to an industrial pharmaceutical fluid bed granulation.

Science.gov (United States)

Lourenço, Vera; Lochmann, Dirk; Reich, Gabriele; Menezes, José C; Herdling, Thorsten; Schewitz, Jens

2012-06-01

The pharmaceutical industry is encouraged within Quality by Design (QbD) to apply science-based manufacturing principles to assure quality not only of new but also of existing processes. This paper presents how QbD principles can be applied to an existing industrial pharmaceutical fluid bed granulation (FBG) process. A three-step approach is presented as follows: (1) implementation of Process Analytical Technology (PAT) monitoring tools at the industrial scale process, combined with multivariate data analysis (MVDA) of process and PAT data to increase the process knowledge; (2) execution of scaled-down designed experiments at a pilot scale, with adequate PAT monitoring tools, to investigate the process response to intended changes in Critical Process Parameters (CPPs); and finally (3) the definition of a process Design Space (DS) linking CPPs to Critical to Quality Attributes (CQAs), within which product quality is ensured by design, and after scale-up enabling its use at the industrial process scale. The proposed approach was developed for an existing industrial process. Through enhanced process knowledge established a significant reduction in product CQAs, variability already within quality specifications ranges was achieved by a better choice of CPPs values. The results of such step-wise development and implementation are described. Copyright © 2012 Elsevier B.V. All rights reserved.

Computational transport phenomena of fluid-particle systems

CERN Document Server

Arastoopour, Hamid; Abbasi, Emad

2017-01-01

This book concerns the most up-to-date advances in computational transport phenomena (CTP), an emerging tool for the design of gas-solid processes such as fluidized bed systems. The authors examine recent work in kinetic theory and CTP and illustrate gas-solid processes’ many applications in the energy, chemical, pharmaceutical, and food industries. They also discuss the kinetic theory approach in developing constitutive equations for gas-solid flow systems and how it has advanced over the last decade as well as the possibility of obtaining innovative designs for multiphase reactors, such as those needed to capture CO2 from flue gases. Suitable as a concise reference and a textbook supplement for graduate courses, Computational Transport Phenomena of Gas-Solid Systems is ideal for practitioners in industries involved with the design and operation of processes based on fluid/particle mixtures, such as the energy, chemicals, pharmaceuticals, and food processing. Explains how to couple the population balance e...

A Photocatalytic Active Adsorbent for Gas Cleaning in a Fixed Bed Reactor

Directory of Open Access Journals (Sweden)

Peter Pucher

2008-01-01

Full Text Available Efficient photocatalysis for gas cleaning purposes requires a large accessible, illuminated active surface in a simple and compact reactor. Conventional concepts use powdered catalysts, which are nontransparent. Hence a uniform distribution of light is difficult to be attained. Our approach is based on a coarse granular, UV-A light transparent, and highly porous adsorbent that can be used in a simple fixed bed reactor. A novel sol-gel process with rapid micro mixing is used to coat a porous silica substrate with TiO2-based nanoparticles. The resulting material posses a high adsorption capacity and a photocatalytic activity under UV-A illumination (PCAA = photocatalytic active adsorbent. Its photocatalytic performance was studied on the oxidation of trichloroethylene (TCE in a fixed bed reactor setup in continuous and discontinuous operation modes. Continuous operation resulted in a higher conversion rate due to less slip while discontinuous operation is superior for a total oxidation to CO2 due to a user-defined longer residence time.

A Chemical Activity Approach to Exposure and Risk Assessment of Chemicals

DEFF Research Database (Denmark)

Gobas, Frank A. P. C.; Mayer, Philipp; Parkerton, Thomas F.

2018-01-01

activity approach, its strengths and limitations, and provides examples of how this concept may be applied to the management of single chemicals and chemical mixtures. The examples demonstrate that the chemical activity approach provides a useful framework for 1) compiling and evaluating exposure......To support the goals articulated in the vision for exposure and risk assessment in the twenty-first century, we highlight the application of a thermodynamic chemical activity approach for the exposure and risk assessment of chemicals in the environment. The present article describes the chemical...... assessment. The article further illustrates that the chemical activity approach can support an adaptive management strategy for environmental stewardship of chemicals where “safe” chemical activities are established based on toxicological studies and presented as guidelines for environmental quality...

Partitioning of trace metals in the chemical fractions of bed-load sediments of Nahr-Ibrahim river, Lebanon

International Nuclear Information System (INIS)

Korfali, Samira I.; Davies, Brian E.

1999-01-01

Full text.Sediments are the ultimate sink of trace elements. The total metal analysis may only give information concerning possible enrichment of metals. The analysis of metal partitioning in the different chemical components of sediments (exchangeable, carbonate, easily reducible, moderately reducible, organic and residual); give a detailed information on the way in which these metals are bound to sediments, their mobilization capacity and their ability to affect water quality under different environmental conditions. The studied river basin is dominated by limestone formation, the enrichment of metals in the carbonate sediment fraction is a high probability. The objective of the study was to determine the percentage of the total metal content (Fe, Mn, Zn, Cu and Pb) in the six chemical fractions of the bed load sediments of Nahr-Ibrahim river during the dry season and verify the role of carbonate for metal sediment deposition. Bed load sediments were sampled at five locations 13Km stretch, upstream from river mouth at two dates, August and October 1996. the dried samples were sieved into three mechanical fractions (1180-250 μm, 250-75 μm and <75 μm). A sequential chemical extraction was carried on each sized sample sediment, Fe, Mn, Zn, Cu and Pb were determined on the extracts by AAS. The reported data showed that Fe in mainly in the residual fraction, Mn in the residual and carbonate fraction, Zn in the residual, carbonate and Fe oxide fraction, Cu in the residual, carbonate and organic fraction, Pb in the carbonate fraction. The carbonate fraction in sediments played the major common role for metal sediment deposition

FUZZY INFERENCE SYSTEM MODELING FOR BED ACTIVE CARBON RE-GENERATION PROCESS (CO2 GAS FACTORY CASE

Directory of Open Access Journals (Sweden)

S. Febriana

2005-01-01

Full Text Available Bed active carbon is one of the most important materials that had great impact in determining level of impurities in production of CO2 gas. In this particular factory case, there is unavailability of standard duration time of heating and cooling and steam flow rate for the re-generation process of bed active carbon. The paper discusses the fuzzy inference system for modeling of re-generation process of bed active carbon to find the optimum setting parameter. The fuzzy inference system was build using real historical daily processing data. After validation process, surface plot analysis was performed to find the optimum setting. The result of re-generation parameter setting is 9-10 hours of heating process, 4.66-5.32 hours of cooling process, and 1500-2500 kg/hr of steam flow rate.

Development and evaluation of diltiazem hydrochloride controlled-release pellets by fluid bed coating process

Directory of Open Access Journals (Sweden)

Mikkilineni Bhanu Prasad

2013-01-01

Full Text Available The aim of the present study was to develop controlled-release pellets of diltiazem HCl with ethyl cellulose and hydroxylpropyl methylcellulose phthalate as the release rate retarding polymers by fluid bed coating technique. The prepared pellets were evaluated for drug content, particle size, subjected to Scanning Electron Microscopy (SEM and Differential Scanning Calori metry (DSC, and evaluated for in vitro release. Stability studies were carried out on the optimized formulations for a period of 3 months. The drug content was in the range of 97%-101%. The mean particle size of the drug-loaded pellets was in the range 700-785 μm. The drug release rate decreased as the concentration of ethyl cellulose increased in the pellet formulations. Among the prepared formulations, FDL10 and FDL11 showed 80% drug release in 16 h, matching with USP dissolution test 6 for diltiazem HCl extended-release capsules. SEM photographs confirmed that the prepared formulations were spherical in nature with a smooth surface. The compatibility between drug and polymers in the drug-loaded pellets was confirmed by DSC studies. Stability studies indicated that the pellets were stable.

CFD analysis of bubble hydrodynamics in a fuel reactor for a hydrogen-fueled chemical looping combustion system

International Nuclear Information System (INIS)

Harichandan, Atal Bihari; Shamim, Tariq

2014-01-01

Highlights: • Computational study of the fuel reactor of chemical looping combustion technology. • The results yield better understanding of the bubble hydrodynamics in fuel reactor. • Increasing the reactor bed length increases the conversion rate. • Small oxygen carrier particles improves the conversion rate. - Abstract: This study investigates the temporal development of bubble hydrodynamics in the fuel reactor of a hydrogen-fueled chemical looping combustion (CLC) system by using a computational model. The model also investigates the molar fraction of products in gas and solid phases. The study assists in developing a better understanding of the CLC process, which has many advantages such as being a potentially promising candidate for an efficient carbon dioxide capture technology. The study employs the kinetic theory of granular flow. The reactive fluid dynamic system of the fuel reactor is customized by incorporating the kinetics of an oxygen carrier reduction into a commercial computational fluid dynamics (CFD) code. An Eulerian multiphase treatment is used to describe the continuum two-fluid model for both gas and solid phases. CaSO 4 and H 2 are used as an oxygen carrier and a fuel, respectively. The computational results are validated with the experimental and numerical results available in the open literature. The CFD simulations are found to capture the features of the bubble formation, rise and burst in unsteady and quasi-steady states very well. The results show a significant increase in the conversion rate with higher dense bed height, lower bed width, higher free board height and smaller oxygen carrier particles which upsurge an overall performance of the CLC plant

Thermal-hydraulic and characteristic models for packed debris beds

International Nuclear Information System (INIS)

Mueller, G.E.; Sozer, A.

1986-12-01

APRIL is a mechanistic core-wide meltdown and debris relocation computer code for Boiling Water Reactor (BWR) severe accident analyses. The capabilities of the code continue to be increased by the improvement of existing models. This report contains information on theory and models for degraded core packed debris beds. The models, when incorporated into APRIL, will provide new and improved capabilities in predicting BWR debris bed coolability characteristics. These models will allow for a more mechanistic treatment in calculating temperatures in the fluid and solid phases in the debris bed, in determining debris bed dryout, debris bed quenching from either top-flooding or bottom-flooding, single and two-phase pressure drops across the debris bed, debris bed porosity, and in finding the minimum fluidization mass velocity. The inclusion of these models in a debris bed computer module will permit a more accurate prediction of the coolability characteristics of the debris bed and therefore reduce some of the uncertainties in assessing the severe accident characteristics for BWR application. Some of the debris bed theoretical models have been used to develop a FORTRAN 77 subroutine module called DEBRIS. DEBRIS is a driver program that calls other subroutines to analyze the thermal characteristics of a packed debris bed. Fortran 77 listings of each subroutine are provided in the appendix

Feeding activity of mussels Mytilus edulis related to near-bed currents and phytoplankton biomass

DEFF Research Database (Denmark)

Dolmer, Per

2000-01-01

The feeding activity of blue mussels Mytilus edulis was investigated in the field and related to near-bottom current velocities and the phytoplankton biomass in the near-bottom water layers for four days. The body content of Chl-a in mussels and their shell gap size were used as indices...... of filtration activity. During days 1 and 2 the near-bed current velocities were low (1.2-2.1 cm s(-1)), and the near-bed phytoplankton biomass was at the same time lower than near the water surface. Between 44 and 69% of the mussels had closed shells and accumulated only small amounts of Chl-a in the body....... During day 3 and day 4 the near-bed current velocities increased to 6.5 and 3.9 cm s(-1). respectively, and the Chl-a was homogeneously distributed in the water column. Now only 17 and 25% of the mussels had closed valves and they accumulated a larger amount of Chl-a. The actual population filtration...

Gas-Liquid Two-Phase Flows Through Packed Bed Reactors in Microgravity

Science.gov (United States)

Motil, Brian J.; Balakotaiah, Vemuri

2001-01-01

The simultaneous flow of gas and liquid through a fixed bed of particles occurs in many unit operations of interest to the designers of space-based as well as terrestrial equipment. Examples include separation columns, gas-liquid reactors, humidification, drying, extraction, and leaching. These operations are critical to a wide variety of industries such as petroleum, pharmaceutical, mining, biological, and chemical. NASA recognizes that similar operations will need to be performed in space and on planetary bodies such as Mars if we are to achieve our goals of human exploration and the development of space. The goal of this research is to understand how to apply our current understanding of two-phase fluid flow through fixed-bed reactors to zero- or partial-gravity environments. Previous experiments by NASA have shown that reactors designed to work on Earth do not necessarily function in a similar manner in space. Two experiments, the Water Processor Assembly and the Volatile Removal Assembly have encountered difficulties in predicting and controlling the distribution of the phases (a crucial element in the operation of this type of reactor) as well as the overall pressure drop.

Creepy landscapes : river sediment entrainment develops granular flow rheology on creeping bed.

Science.gov (United States)

Prancevic, J.; Chatanantavet, P.; Ortiz, C. P.; Houssais, M.; Durian, D. J.; Jerolmack, D. J.

2015-12-01

To predict rates of river sediment transport, one must first address the zeroth-order question: when does sediment move? The concept and determination of the critical fluid shear stress remains hazy, as observing particle motion and determining sediment flux becomes increasingly hard in its vicinity. To tackle this problem, we designed a novel annular flume experiment - reproducing an infinite river channel - where the refractive index of particles and the fluid are matched. The fluid is dyed with a fluorescent powder and a green laser sheet illuminates the fluid only, allowing us to observe particle displacements in a vertical plane. Experiments are designed to highlight the basic granular interactions of sediment transport while suppressing the complicating effects of turbulence; accordingly, particles are uniform spheres and Reynolds numbers are of order 1. We have performed sediment transport measurements close to the onset of particle motion, at steady state, and over long enough time to record averaged rheological behavior of particles. We find that particles entrained by a fluid exhibit successively from top to bottom: a suspension regime, a dense granular flow regime, and - instead of a static bed - a creeping regime. Data from experiments at a range of fluid stresses can be collapsed onto one universal rheologic curve that indicates the effective friction is a monotonic function of a dimensionless number called the viscous number. These data are in remarkable agreement with the local rheology model proposed by Boyer et al., which means that dense granular flows, suspensions and bed-load transport are unified under a common frictional flow law. Importantly, we observe slow creeping of the granular bed even in the absence of bed load, at fluid stresses that are below the apparent critical value. This last observation challenges the classical definition of the onset of sediment transport, and points to a continuous transition from quasi-static deformation to

Copper-arsenic decoupling in an active geothermal system: A link between pyrite and fluid composition

Science.gov (United States)

Tardani, Daniele; Reich, Martin; Deditius, Artur P.; Chryssoulis, Stephen; Sánchez-Alfaro, Pablo; Wrage, Jackie; Roberts, Malcolm P.

2017-05-01

Over the past few decades several studies have reported that pyrite hosts appreciable amounts of trace elements which commonly occur forming complex zoning patterns within a single mineral grain. These chemical zonations in pyrite have been recognized in a variety of hydrothermal ore deposit types (e.g., porphyry Cu-Mo-Au, epithermal Au deposits, iron oxide-copper-gold, Carlin-type and Archean lode Au deposits, among others), showing, in some cases, marked oscillatory alternation of metals and metalloids in pyrite growth zones (e.g., of Cu-rich, As-(Au, Ag)-depleted zones and As-(Au, Ag)-rich, Cu-depleted zones). This decoupled geochemical behavior of Cu and As has been interpreted as a result of chemical changes in ore-forming fluids, although direct evidence connecting fluctuations in hydrothermal fluid composition with metal partitioning into pyrite growth zones is still lacking. In this study, we report a comprehensive trace element database of pyrite from the Tolhuaca Geothermal System (TGS) in southern Chile, a young and active hydrothermal system where fewer pyrite growth rims and mineralization events are present and the reservoir fluid (i.e. ore-forming fluid) is accessible. We combined the high-spatial resolution and X-ray mapping capabilities of electron microprobe analysis (EMPA) with low detection limits and depth-profiling capacity of secondary-ion mass spectrometry (SIMS) in a suite of pyrite samples retrieved from a ∼1 km drill hole that crosses the argillic (20-450 m) and propylitic (650-1000 m) alteration zones of the geothermal system. We show that the concentrations of precious metals (e.g., Au, Ag), metalloids (e.g., As, Sb, Se, Te), and base and heavy metals (e.g., Cu, Co, Ni, Pb) in pyrite at the TGS are significant. Among the elements analyzed, As and Cu are the most abundant with concentrations that vary from sub-ppm levels to a few wt.% (i.e., up to ∼5 wt.% As, ∼1.5 wt.% Cu). Detailed wavelength-dispersive spectrometry (WDS) X

Computational Flow Modeling of Hydrodynamics in Multiphase Trickle-Bed Reactors

Science.gov (United States)

Lopes, Rodrigo J. G.; Quinta-Ferreira, Rosa M.

2008-05-01

This study aims to incorporate most recent multiphase models in order to investigate the hydrodynamic behavior of a TBR in terms of pressure drop and liquid holdup. Taking into account transport phenomena such as mass and heat transfer, an Eulerian k-fluid model was developed resulting from the volume averaging of the continuity and momentum equations and solved for a 3D representation of the catalytic bed. Computational fluid dynamics (CFD) model predicts hydrodynamic parameters quite well if good closures for fluid/fluid and fluid/particle interactions are incorporated in the multiphase model. Moreover, catalytic performance is investigated with the catalytic wet oxidation of a phenolic pollutant.

Nickel removal from nickel plating waste water using a biologically active moving-bed sand filter.

Science.gov (United States)

Pümpel, Thomas; Macaskie, Lynne E; Finlay, John A; Diels, Ludo; Tsezos, Marios

2003-12-01

Efficient removal of dissolved nickel was observed in a biologically active moving-bed 'MERESAFIN' sand filter treating rinsing water from an electroless nickel plating plant. Although nickel is fully soluble in this waste water, its passage through the sand filter promoted rapid removal of approximately 1 mg Ni/l. The speciation of Ni in the waste water was modelled; the most probable precipitates forming under the conditions in the filter were predicted using PHREEQC. Analyses of the Ni-containing biosludge using chemical, electron microscopical and X-ray spectroscopic techniques confirmed crystallisation of nickel phosphate as arupite (Ni3(PO4)2 x 8H2O), together with hydroxyapatite within the bacterial biofilm on the filter sand grains. Biosorption contributed less than 1% of the overall sequestered nickel. Metabolising bacteria are essential for the process; the definitive role of specific components of the mixed population is undefined but the increase in pH promoted by metabolic activity of some microbial components is likely to promote nickel desolubilisation by others.

Emergence of traveling wave endothermic reaction in a catalytic fixed bed under microwave heating

International Nuclear Information System (INIS)

Gerasev, Alexander P.

2017-01-01

This paper presents a new phenomenon in a packed bed catalytic reactor under microwave heating - traveling wave (moving reaction zones) endothermic chemical reaction. A two-phase model is developed to simulate the nonlinear dynamic behavior of the packed bed catalytic reactor with an irreversible first-order chemical reaction. The absorbed microwave power was obtained from Lambert's law. The structure of traveling wave endothermic chemical reaction was explored. The effects of the gas velocity and microwave power on performance of the packed bed catalytic reactor were presented. Finally, the effects of the change in the location of the microwave source at the packed bed reactor was demonstrated. - Highlights: • A new phenomenon - traveling waves of endothermic reaction - is predicted. • The physical and mathematical model of a packed bed catalytic reactor under microwave heating is presented. • The structure of the traveling waves is explored. • The configuration of heating the packed bed reactor via microwave plays a key role.

Local heat transfer coefficient in a fluidized bed

International Nuclear Information System (INIS)

Al-Busoul, A. M.

1999-01-01

This paper presents an experimental study for the local heat transfer coefficient. The experiments was conducted inside a reactor with inner diameter (I D = 142mm) at atmospheric conditions (temperature mean value = 29 deg.) The bed was heated by means of a parochial electric heater with a diameter of (d h = 29 mm) and a constant power of 5W. The following factors varied: particles type and diameter, fluid velocity, bed height and heater position inside the reactor. The results were presented and discussed. (author). 15 refs., 7 figs

Incipient motion of gravel and coal beds

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

2. 1Department of Civil Engineering, Indian Institute of Technology, ... the particle size distribution curve following the relationship by Christensen .... where f = friction factor, ρ = mass density of fluid, and V = mean velocity of flow. .... for the incipient motion of gravel and coal beds have been represented by simple empirical.

Chemical characteristics of hydrothermal fluids from the TAG Mound of the Mid-Atlantic Ridge in August 1994: Implications for spatial and temporal variability of hydrothermal activity

Science.gov (United States)

Gamo, Toshitaka; Chiba, Hitoshi; Masuda, Harue; Edmonds, Henrietta N.; Fujioka, Kantaro; Kodama, Yukio; Nanba, Hiromi; Sano, Yuji

The TAG hydrothermal mound on the Mid-Atlantic Ridge (26°08‧N, 44°50‧W) was revisited in August 1994 with the submersible Shinkai 6500 in order to characterize time-series fluid chemistry prior to the ODP drilling. Fluid samples were taken from both black smokers and white smokers. Si, pH, alkalinity, H2S, major cations (Na+, K+, Ca2+, Mg2+), major anions (Cl-, SO42-), and minor elements (Li, Sr, B, Fe, Mn, Cu, Zn, Br) as well as Sr isotope ratios were measured. We report the first Br/Cl ratios for the TAG hydrothermal fluids, showing no fractionation between Br and Cl during the fluid-rock interaction. This study shows small changes in composition of the black smoker fluids from the 1990 data (Edmond et al., 1995). Changes of pH, alkalinity, Fe, K, and 87Sr/86Sr values are suggestive of subsurface FeS precipitation and a decrease of water/rock ratio at a deeper reaction zone. Differences in chemical characteristics between the black and white smoker fluids were similarly observed as in 1990.

Amniotic fluid gamma-glutamyl transpeptidase activity during the second trimester.

Science.gov (United States)

Legge, M; Potter, H C

1986-03-12

Gamma glutamyl transpeptidase (GGTP) activity was determined in second trimester amniotic fluid taken from normal fetuses and those with fetal abnormalities. GGTP activity decreased with advancing gestation. Increasing meconium contamination correlated with an increase in GGTP activity as did increasing fetal blood contamination. Maternal blood did not affect GGTP activity. Anencephaly did not significantly alter the GGTP activity, however, fetuses with spina bifida had significantly lower activity. Klinefelters and Turners syndromes both had GGTP activity close to the 50th percentile, and two trisomy 21 fetuses had GGTP activity below the 40th percentile. Two trisomy 18 fetuses and two translocation Downs syndromes (46 XY, t (14;21) had GGTP activities considerably lower than the 20th percentile as did a fetus with gastroschisis. Second trimester amniotic fluid GGTP activity may provide an easy preliminary test to screen amniotic fluids for the possibility of certain fetal chromosome abnormalities.

Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Liu, Rongzheng; Liu, Malin, E-mail: liumalin@tsinghua.edu.cn; Chang, Jiaxing [Tsinghua University, Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology (China)

2017-02-15

A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H{sub 2} system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

International Nuclear Information System (INIS)

Liu, Rongzheng; Liu, Malin; Chang, Jiaxing

2017-01-01

A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H_2 system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

Anaerobic fluidized bed treatment of a tannery wastewater

Energy Technology Data Exchange (ETDEWEB)

Chen, S.J.; Li, C.T.; Shieh, W.K.

1988-11-01

The anaerobic fluidized bed system, in conjunction with neutralization and chemical coagulation/flocculation, was evaluated for treatment of a tannery wastewater produced from a chrome tanning operation. Neutralization with 1 N sulphuric acid was effective for removal of chromate, with complete removal achieved at pH=8.0. Chemical coagulation/flocculation with alum at a dosage of 200 mg/L was able to remove 97% of feed SS and 65% of feed grease. Evaluation of the performance of the anaerobic fluidized bed system indicated more than 75% of feed COD could be removed up to an F/M ratio of approximately 0.4 g COD/g TVS center dot day. The observed methane production rate was 0.221 of CH/sub 4/ produced per gram COD removed. The anaerobic fluidized bed system could provide an effective treatment of a pretreated tannery wastewater.

Determination and modeling of the influence of the fluid-dynamics in hydro-treating bench scale plants

Energy Technology Data Exchange (ETDEWEB)

Burkhardt, T.

1999-09-16

At an industrial scale, the hydro-treating of oil fractions is carried out in multiphase fixed bed reactors. The oil and hydrogen cross the catalyst bed, usually in co-current downflow. Since the product specifications are steadily becoming more severe, the testing of new catalysts and of modified operating conditions in pilot plants becomes increasingly important. Although these pilot plants are frequently by a factor of 100 000 smaller than the industrial units, they still have to allow the up-scaling to industrial units. In the literature relatively low conversion degrees in pilot plants are frequently reported, especially in downflow. The significantly lower fluid velocities in pilot plants seem to be responsible for such differences, as the influence of fluid-dynamic non-idealities and of the extra-particle mass transfer phenomena increases with a decrease of the fluid velocities. In the present work, the influence of important fluid-dynamic non-idealities on the hydro-treating of gas oil fractions in pilot plants was examined. This was done on the one hand in experiments with different pilot plants and on the other hand by simulations with an especially developed multiphase model. The phenomena were considered as well in an isolated manner. In order to examine any interactions with the chemical reactions, they were also studied in a reactive system. This methodology was applied to the phenomena, 'axial dispersion'and 'gas-liquid mass transfer'. (author)

Trickle bed reactor for the oxidation of phenol over active carbon catalyst

OpenAIRE

Gabbiye, Nigus; Font Capafons, Josep; Fortuny Sanromá, Agustín; Bengoa, Christophe José; Fabregat Llangotera, Azael; Stüber, Frank Erich

2009-01-01

The catalytic wet air oxidation of phenol using activated carbon has been performed in a laboratory trickle bed reactor over a wide range of operating variables (PO2, T, FL and Cph,o) and hydrodynamic conditions. The influence of different start-up procedures (saturation of activated carbon) has also been tested. Further improvement of activity and stability has been checked for by using dynamic TBR operation concept or impregnated Fe/carbon catalyst. The results obtained confi...

Chemical Warfare Agent Simulants in Gamble’s Fluid: Is the Fluid Toxic? Can It Be Made Safer by Inclusion of Solid Nanocrystalline Metal Oxides?

Directory of Open Access Journals (Sweden)

Dennis Karote

2013-01-01

Full Text Available The reactions of chemical warfare agent simulants, 2-chloroethyl ethyl sulfide (2-CEES and di-i-propyl fluoro phosphate (DFP, in fluids have been investigated. Data analyses confirm the major degradation pathway to be hydrolysis of 2-CEES to 2-hydroxyethyl ethyl sulfide, along with minor self-condensation products. Among the three fluids examined, 2-CEES degradation was the fastest in Gamble’s fluid during a 96 h period. Upon addition of Exceptional Hazard Attenuation Materials (EHAMs to 2-CEES containing Gamble’s fluid, degradation was generally improved during the first 24 h period. The 96 h outcome was similar for fluid samples with or without EHAM 2 and EHAM 4. EHAM 1-added fluid contained only one degradation product, 2-nitroethyl ethyl sulfide. DFP degradation was the slowest in Gamble’s fluid, but was enhanced by the addition of EHAMs. FTIR and solid state 31P NMR confirm the destructive adsorption of 2-CEES and DFP by the EHAMs. The results collectively demonstrate that 2-CEES and DFP decompose to various extents in Gamble’s fluid over a 96 h period but the fluid still contains a considerable amount of intact simulant. EHAM 1 appears to be promising for 2-CEES and DFP mitigation while EHAM 2 and EHAM 4 work well for early on concentration reduction of 2-CEES and DFP.

Control of chemical usage in drilling fluid formulations to minimize discharge to the environment

International Nuclear Information System (INIS)

Geehan, T.; Forbes, D.M.; Moore, D.J.

1991-01-01

A reduction in the environmental footprint from drilling operations can best be addressed by minimizing the sources of that footprint. One of the principal sources of possible environmental damage is drilling fluid and drill solid discharge. The toxicity as measured by acute and/or sub-chronic testing regimes depends on the composition of the drilling fluid/drill solids slurry. The trend within the drilling fluids industry has been to direct its attention to finding drilling fluid products which alone and in combination are considered to be non-toxic as determined by required testing procedures. This paper goes on to describe a parallel approach in which the total volume of chemicals discharged (whether considered toxic or benign) is reduced. Both approaches can be considered complimentary. The reduction in volume/mass of discharge is achieved by increased monitoring of both drilling fluid properties, composition and solids control operational efficiency. Additionally the increased monitoring allows less complicated formulations to be used to produce the desired drilling fluid properties; as specified by the mud programme. The need for more complete rigsite monitoring packages, will become more important as oilbased muds are replaced by waterbased mud for difficult drilling situations with stricter environmental regulations on discharge of drilling waste. The paper also outlines how the optimization of the drilling fluid operation was linked to a reduction in drilling fluid costs at the same time maintaining drilling efficiency

Mean 24-hours sympathetic nervous system activity decreases during head-down tilted bed rest but not during microgravity

Science.gov (United States)

Christensen, Nj; Heer, M.; Ivanova, K.; Norsk, P.

Sympathetic nervous system activity is closely related to gravitational stress in ground based experiments. Thus a high activity is present in the standing-up position and a very low activity is observed during acute head-out water immersion. Adjustments in sympathetic activity are necessary to maintain a constant blood pressure during variations in venous return. Head-down tilted bed rest is applied as a model to simulate changes observed during microgravity. The aim of the present study was to test the hypothesis that mean 24-hours sympathetic activity was low and similar during space flight and in ground based observation obtained during long-term head-down tilted bed rest. Forearm venous plasma noradrenaline was measured by a radioenzymatic technique as an index of muscle sympathetic activity and thrombocyte noradrenaline and adrenaline were measured as indices of mean 24-hours sympathoadrenal activity. Previous results have indicated that thrombocyte noradrenaline level has a half-time of 2 days. Thus to reflect sympathetic activity during a specific experiment the study period must last for at least 6 days and a sample must be obtained within 12 hours after the experiment has ended. Ten normal healthy subjects were studied before and during a 14 days head-down tilted bed rest as well as during an ambulatory study period of a similar length. The whole experiment was repeated while the subjects were on a low calorie diet. Thrombocyte noradrenaline levels were studied in 4 cosmonauts before and within 12 hours after landing after more than 7 days in flight. Thrombocyte noradrenaline decreased markedly during the head-down tilted bed rest (pdifferent in cosmonauts and in subjects participating in the head down tilted bed rest study (170± 29% (Mean± SEM) vs. 57± 7%, respectively; presponse to combined effects of a reduced plasma volume and an increased vascular capacity in flight.

Preparation and surface characterization of activated carbons from Euphorbia rigida by chemical activation with ZnCl2, K2CO3, NaOH and H3PO4

International Nuclear Information System (INIS)

Kılıç, Murat; Apaydın-Varol, Esin; Pütün, Ayşe Eren

2012-01-01

Highlights: ► An arid land plant evaluated as low cost activated carbon precursor. ► Four types of different chemical activation agents are used. ► Higher surface area (2600 m 2 /g) obtained by chemical activation. ► Obtained activated carbon can be effectively used as an adsorbent for the removal of toxic pollutants from aqueous solutions. - Abstract: Preparation of activated carbons from Euphorbia rigida by chemical activation with different impregnation agents and ratios was studied. ZnCl 2 , K 2 CO 3 , NaOH and H 3 PO 4 were used as chemical activation agents and four impregnation ratios (25–50–75–100%) by mass were applied on biomass. Activation is applied to impregnated biomass samples at 700 °C under sweeping gas in a fixed bed reactor. For determination of chemical and physical properties of the obtained activated carbons; elemental analysis was applied to determine the elemental composition (C, H, N, O) and FT-IR spectra was used to analyze the functional groups. BET equation was used to calculate the surface areas of activated carbons. For understanding the changes in the surface structure, activated carbons were conducted to Scanning Electron Microscopy (SEM). Maximum BET surface area (2613 m 2 /g) was reached with 75% K 2 CO 3 impregnated biomass sample. Experimental results showed that impregnation types and ratios have a significant effect on the pore structure of activated carbon and E. rigida seems to be an alternative precursor for commercial activated carbon production.

in Spouted Bed

Directory of Open Access Journals (Sweden)

Bronislaw Buczek

2013-01-01

Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

Absorption in a three-phase fluidized bed I: Hydrodynamic investigations

Directory of Open Access Journals (Sweden)

Pejanović Srđan M.

2003-01-01

Full Text Available The hydrodynamic properties of a three phase fluidized bed with low density inert spherical packing, fluidized by the interaction of a gas flowing upwards and a liquid flowing downwards through the column, were investigated. It was found that the pressure drop, liquid hold up and dynamic bed height increase with both increasing liquid and gas flow rate. While the dynamic bed height and minimum fluidization velocity remain unchanged, both the pressure drop and liquid hold up increase with increasing density of the packing. Therefore, an increase in packing density causes more intensive mass transfer between the fluid phases than packed columns. It was shown that increase of the liquid flow rate causes an increase of both the effective liquid and gas velocity through the fluidized bed, which may also improve mass transfer.

Application of the CPA equation of state to reservoir fluids in presence of water and polar chemicals

DEFF Research Database (Denmark)

Yan, Wei; Kontogeorgis, Georgios; Stenby, Erling Halfdan

2009-01-01

to reservoir fluids in presence of water and polar chemical Such as methanol and monoethylene glycol. With a minimum number of adjustable parameters from binary pairs, satisfactory results have been obtained for different types of phase equilibria in reservoir fluid systems and several relevant model......The complex phase equilibrium between reservoir fluids and associating compounds like water, methanol and glycols has become more and more important as the increasing global energy demand pushes the oil industry to target reservoirs with extreme or complicated conditions, such as deep or offshore...

Study of Pressure Drop in Fixed Bed Reactor Using a Computational Fluid Dynamics (CFD Code

Directory of Open Access Journals (Sweden)

Soroush Ahmadi

2018-04-01

Full Text Available Pressure drops of water and critical steam flowing in the fixed bed of mono-sized spheres are studied using SolidWorks 2017 Flow Simulation CFD code. The effects of the type of bed formation, flow velocity, density, and pebble size are evaluated. A new equation is concluded from the data, which is able to estimate pressure drop of a packed bed for high particle Reynolds number, from 15,000 to 1,000,000.

Co-current descending two-phase flows in inclined packed beds : experiments versus simulations

Energy Technology Data Exchange (ETDEWEB)

Atta, A.; Nigam, K.D.P.; Roy, S. [Inst. of Technology, New Delhi (India). Dept. of Chemical Engineering; Schubert, M.; Larachi, F. [Laval Univ., Quebec City, PQ (Canada). Dept. of Chemical Engineering

2010-10-15

This paper presented a numerical simulation for an inclined packed bed configuration for two-phase co-current downward flow. A two-phase Eulerian computational fluid dynamics (CFD) model was used to predict the hydrodynamic behaviour. Two different modelling strategies were compared, notably a straight tube with an artificially inclined gravity, and an inclined geometry with straight gravity. The effect of inclination angle of a packed bed on its gas-liquid flow segregation and liquid saturation spatial distribution was measured for varying inclinations and fluid velocities. The CFD model was adapted from a trickle-bed vertical configuration and based on the porous media concept. The predicted pressure drops for the inclined gravity were found to be insensitive to inclination. Therefore, simulations to study the parameters that influence the reduced liquid saturation were performed only with the inclined geometry case. Experimental data obtained using electrical capacitance tomography was used to validate the model predictions. The study showed that a trickle bed CFD model for vertically straight reactors can be effectively implemented in inclined reactor geometries. However, additional research is needed to formulate appropriate drag force closures which should be incorporated in the CFD model for improved quantitative estimation of inclined bed hydrodynamics. 22 refs., 10 figs.

Computerized tomography with X-rays: an instrument in the analysis physico-chemical between formations and drilling fluids interactions

International Nuclear Information System (INIS)

Coelho, Marcus Vinicius Cavalcante

1998-01-01

In this study it is demonstrated the applicability of the Computerized Tomography technique with x-rays to evaluate the reactivity degree between various drilling fluids and argillaceous sediments (Shales and Sandstones). The research has been conducted in the Rock-Fluid Interaction Pressure Simulator (RFIPS), where the possible physico-chemical alterations can be observed through successive tomography images, which are obtained during the flow of the fluid through the samples. In addition, it was noticed the formation of mud cake in Berea Sandstones samples in the RFIPS, though the Computerized Tomography with X-rays, when utilizing drilling fluids weighted with the baryte. (author)

Development of an experimental radioisotope based process tomography system for research applications in a cold trickle bed column

International Nuclear Information System (INIS)

Sau, Madhusudan; Kumar, Pravesh; Kumar, Umesh; Acharya, Rajesh; Singh, Gursharan

2009-01-01

In chemical and petrochemical engineering applications, random and structured packing are used in process columns to enhance the heat and mass transfer between two phases. The packing used in such columns is meant to obtain a high specific interfacial area. It is of paramount importance for scale-up and design of trickle bed process columns, to understand and predict the complex multiphase fluid dynamics. In simplified terms, the phase holdup, solid packing distribution in terms of density and gas and liquid velocities among other important parameters need to be qualitatively and quantitatively understood. In the petrochemical industry, many processes are carried out using fixed bed reactors with concurrent upward and downward gas and liquid flows. In order to characterize the liquid and gas flow distribution through a mock-up column, data on planar and volume density distribution using computed tomographic measurements are very helpful. The paper describes the development efforts of a multi-detector 137 Cs radioisotope based in-situ tomography scanner suitable for 600mm dia. cold trickle bed reactor. The development work is at present in progress. The schematics and development of the scanner gantry is described in this paper. (author)

Iteration scheme for implicit calculations of kinetic and equilibrium chemical reactions in fluid dynamics

International Nuclear Information System (INIS)

Ramshaw, J.D.; Chang, C.H.

1995-01-01

An iteration scheme for the implicit treatment of equilibrium chemical reactions in partial equilibrium flow has previously been described. Here we generalize this scheme to kinetic reactions as well as equilibrium reactions. This extends the applicability of the scheme to problems with kinetic reactions that are fast in regions of the flow field but slow in others. The resulting scheme thereby provides a single unified framework for the implicit treatment of an arbitrary number of coupled equilibrium and kinetic reactions in chemically reacting fluid flow. 10 refs., 2 figs

Exercise countermeasures for bed-rest deconditioning

Science.gov (United States)

Greenleaf, John (Editor)

1993-01-01

The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

Continuous Fixed-Bed Column Study and Adsorption Modeling: Removal of Lead Ion from Aqueous Solution by Charcoal Originated from Chemical Carbonization of Rubber Wood Sawdust

Directory of Open Access Journals (Sweden)

Swarup Biswas

2015-01-01

Full Text Available The efficiency of chemically carbonized rubber wood sawdust for the removal of lead ion from the aqueous stream was investigated by column process. Chemically carbonized rubber wood sawdust was prepared by treating the sawdust with H2SO4 and HNO3. Maximum removal of lead ion in column process was found as 38.56 mg/g. The effects of operating parameters such as flow rate, bed depth, concentration, and pH were studied in column mode. Experimental data confirmed that the adsorption capacity increased with the increasing inlet concentration and bed depth and decreased with increasing flow rate. Thomas, Yoon-Nelson, and Adams-Bohart models were used to analyze the column experimental data and the relationship between operating parameters. Chemically carbonized rubber wood sawdust was characterized by using Fourier transform infrared spectroscopy. Scanning electron microscope was also utilized for morphological analysis of the adsorbent. Furthermore X-ray fluorescence spectrum analysis and energy dispersive X-ray spectroscopy were also used for the confirmation of lead adsorption process.

Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

Energy Technology Data Exchange (ETDEWEB)

Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

2014-02-15

The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

Mass transfer in porous media with heterogeneous chemical reaction

Directory of Open Access Journals (Sweden)

Souza S.M.A.G.Ulson de

2003-01-01

Full Text Available In this paper, the modeling of the mass transfer process in packed-bed reactors is presented and takes into account dispersion in the main fluid phase, internal diffusion of the reactant in the pores of the catalyst, and surface reaction inside the catalyst. The method of volume averaging is applied to obtain the governing equation for use on a small scale. The local mass equilibrium is assumed for obtaining the one-equation model for use on a large scale. The closure problems are developed subject to the length-scale constraints and the model of a spatially periodic porous medium. The expressions for effective diffusivity, hydrodynamic dispersion, total dispersion and the Darcy's law permeability tensors are presented. Solution of the set of final equations permits the variations of velocity and concentration of the chemical species along the packed-bed reactors to be obtained.

Development and clinical application of a computer-aided real-time feedback system for detecting in-bed physical activities.

Science.gov (United States)

Lu, Liang-Hsuan; Chiang, Shang-Lin; Wei, Shun-Hwa; Lin, Chueh-Ho; Sung, Wen-Hsu

2017-08-01

Being bedridden long-term can cause deterioration in patients' physiological function and performance, limiting daily activities and increasing the incidence of falls and other accidental injuries. Little research has been carried out in designing effective detecting systems to monitor the posture and status of bedridden patients and to provide accurate real-time feedback on posture. The purposes of this research were to develop a computer-aided system for real-time detection of physical activities in bed and to validate the system's validity and test-retest reliability in determining eight postures: motion leftward/rightward, turning over leftward/rightward, getting up leftward/rightward, and getting off the bed leftward/rightward. The in-bed physical activity detecting system consists mainly of a clinical sickbed, signal amplifier, a data acquisition (DAQ) system, and operating software for computing and determining postural changes associated with four load cell sensing components. Thirty healthy subjects (15 males and 15 females, mean age = 27.8 ± 5.3 years) participated in the study. All subjects were asked to execute eight in-bed activities in a random order and to participate in an evaluation of the test-retest reliability of the results 14 days later. Spearman's rank correlation coefficient was used to compare the system's determinations of postural states with researchers' recordings of postural changes. The test-retest reliability of the system's ability to determine postures was analyzed using the interclass correlation coefficient ICC(3,1). The system was found to exhibit high validity and accuracy (r = 0.928, p system was particularly accurate in detecting motion rightward (90%), turning over leftward (83%), sitting up leftward or rightward (87-93%), and getting off the bed (100%). The test-retest reliability ICC(3,1) value was 0.968 (p system developed in this study exhibits satisfactory validity and reliability in detecting changes in-bed

Advanced fluid bed calciner information on IR-100 award

International Nuclear Information System (INIS)

Druby, M.C.; Owen, T.J.; Klem, M.J.

1986-01-01

The advanced fluidized bed calciner provides time, temperature and turbulence to change a liquid slurry such as ammonium diuranate into a uranium dioxide powder. The liquid is sprayed into a hot chamber (up to 700 0 C) which includes thousands of tiny metal beads, about the size of BB's. The constantly moving beads provide an efficient heat transfer media for the immediate transformation of the slurry droplets into dry particles of powder, which are carried out by hot nitrogen gas and recovered in a collector

The behavior of xenon dynamic adsorption on granular activated carbon packed bed adsorber

International Nuclear Information System (INIS)

Chongyang Zhou; Shujuan Feng; Guoqing Zhou; Yuren Jin; Junfu Liang; Jingming Xu

2011-01-01

In order to retard radioxenon release into the atmosphere from nuclear power station or to sensitively monitor its concentration to ensure environmental and human safety, it is necessary to know the behavior of xenon dynamic adsorption on granular activated carbon pack bed adsorber. The quantities, including the dynamic adsorption coefficient (k d ), the amount of xenon adsorbed (q), the length of mass transfer zone (L MTZ ) and the length of the unused bed (LUB), used to describe the adsorption behavior, were sorted out and calculated. The factors, including xenon concentrations, pressures and temperatures, to affect these quantities were investigated. The results show that: (1) The values of k d and q decrease with increasing temperatures, but increase with increasing pressures, (2) The values of L MTZ and LUB increase with increasing temperatures or pressures, but are independent of concentrations. Knowledge of these quantities is very helpful for packed bed adsorber operation. (author)

Coupling microscopic and mesoscopic scales to simulate chemical equilibrium between a nanometric carbon cluster and detonation products fluid.

Science.gov (United States)

Bourasseau, Emeric; Maillet, Jean-Bernard

2011-04-21

This paper presents a new method to obtain chemical equilibrium properties of detonation products mixtures including a solid carbon phase. In this work, the solid phase is modelled through a mesoparticle immersed in the fluid, such that the heterogeneous character of the mixture is explicitly taken into account. Inner properties of the clusters are taken from an equation of state obtained in a previous work, and interaction potential between the nanocluster and the fluid particles is derived from all-atoms simulations using the LCBOPII potential (Long range Carbon Bond Order Potential II). It appears that differences in chemical equilibrium results obtained with this method and the "composite ensemble method" (A. Hervouet et al., J. Phys. Chem. B, 2008, 112.), where fluid and solid phases are considered as non-interacting, are not significant, underlining the fact that considering the inhomogeneity of such system is crucial.

Prolonged effect of fluid flow stress on the proliferative activity of mesothelial cells after abrupt discontinuation of fluid streaming

International Nuclear Information System (INIS)

Aoki, Shigehisa; Ikeda, Satoshi; Takezawa, Toshiaki; Kishi, Tomoya; Makino, Junichi; Uchihashi, Kazuyoshi; Matsunobu, Aki; Noguchi, Mitsuru; Sugihara, Hajime; Toda, Shuji

2011-01-01

Highlights: ► Late-onset peritoneal fibrosis leading to EPS remains to be elucidated. ► Fluid streaming is a potent factor for peritoneal fibrosis in PD. ► We focused on the prolonged effect of fluid streaming on mesothelial cell kinetics. ► A history of fluid streaming exposure promoted mesothelial proliferative activity. ► We have thus identified a potent new factor for late-onset peritoneal fibrosis. -- Abstract: Encapsulating peritoneal sclerosis (EPS) often develops after transfer to hemodialysis and transplantation. Both termination of peritoneal dialysis (PD) and transplantation-related factors are risks implicated in post-PD development of EPS, but the precise mechanism of this late-onset peritoneal fibrosis remains to be elucidated. We previously demonstrated that fluid flow stress induced mesothelial proliferation and epithelial–mesenchymal transition via mitogen-activated protein kinase (MAPK) signaling. Therefore, we speculated that the prolonged bioactive effect of fluid flow stress may affect mesothelial cell kinetics after cessation of fluid streaming. To investigate how long mesothelial cells stay under the bioactive effect brought on by fluid flow stress after removal of the stress, we initially cultured mesothelial cells under fluid flow stress and then cultured the cells under static conditions. Mesothelial cells exposed to fluid flow stress for a certain time showed significantly high proliferative activity compared with static conditions after stoppage of fluid streaming. The expression levels of protein phosphatase 2A, which dephosphorylates MAPK, in mesothelial cells changed with time and showed a biphasic pattern that was dependent on the duration of exposure to fluid flow stress. There were no differences in the fluid flow stress-related bioactive effects on mesothelial cells once a certain time had passed. The present findings show that fluid flow stress exerts a prolonged bioactive effect on mesothelial cells after termination

Biomass Gasification in Internal Circulating Fluidized Beds: a Thermodynamic Predictive Tool

Czech Academy of Sciences Publication Activity Database

Miccio, F.; Svoboda, Karel; Schosger, J.-P.; Baxter, D.

2008-01-01

Roč. 25, č. 4 (2008), s. 721-726 ISSN 0256-1115 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized bed * gasification * fluidized bed Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.830, year: 2008

Feeding activity of mussels Mytilus edulis related to near-bed currents and phytoplankton biomass

DEFF Research Database (Denmark)

Dolmer, Per

2000-01-01

The feeding activity of blue mussels Mytilus edulis was investigated in the field and related to near-bottom current velocities and the phytoplankton biomass in the near-bottom water layers for four days. The body content of Chl-a in mussels and their shell gap size were used as indices of filtra......The feeding activity of blue mussels Mytilus edulis was investigated in the field and related to near-bottom current velocities and the phytoplankton biomass in the near-bottom water layers for four days. The body content of Chl-a in mussels and their shell gap size were used as indices...... of filtration activity. During days 1 and 2 the near-bed current velocities were low (1.2-2.1 cm s(-1)), and the near-bed phytoplankton biomass was at the same time lower than near the water surface. Between 44 and 69% of the mussels had closed shells and accumulated only small amounts of Chl-a in the body....... During day 3 and day 4 the near-bed current velocities increased to 6.5 and 3.9 cm s(-1). respectively, and the Chl-a was homogeneously distributed in the water column. Now only 17 and 25% of the mussels had closed valves and they accumulated a larger amount of Chl-a. The actual population filtration...

Long Duration Head Down Tilt Bed Rest and Spaceflight Effects on Neurocognitive Performance: Extent, Longevity and Neural Bases

Science.gov (United States)

Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Cassady, K.; Yuan, P.; Kofman, I. S.; De Dios, Y. E.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

2017-01-01

We have recently completed a long duration head down tilt bed rest (HDBR) study in which we performed structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations in a spaceflight analog environment. We are also collecting the same measures in crewmembers prior to and following a six month International Space Station mission. We will present data demonstrating that bed rest resulted in functional mobility and balance deterioration with recovery post-HDBR. We observed numerous changes in brain structure, function, and connectivity relative to a control group which were associated with pre to post bed rest changes in sensorimotor function. For example, gray matter volume (GMv) increased in posterior parietal areas and decreased in frontal regions. GMv increases largely overlapped with fluid decreases and vice versa. Larger increases in precentral gyrus (M1)/ postcentral gyrus (S1+2) GMv and fluid decreases were associated with smaller balance decrements. Vestibular activation in the bilateral insular cortex increased with bed rest and subsequently recovered. Larger increases in vestibular activation in multiple brain regions were associated with greater decrements in balance and mobility. We found connectivity increases between left M1 with right S1+2 and the superior parietal lobule, and right vestibular cortex with the cerebellum. Decreases were observed between right Lobule VIII with right S1+2 and the supramarginal gyrus, right posterior parietal cortex (PPC) with occipital regions, and the right superior posterior fissure with right Crus I and II. Connectivity strength between left M1 and right S1+2/superior parietal lobule increased the most in individuals that exhibited the least balance impairments. In sum, we observed HDBR-related changes in measures of brain structure, function, and network connectivity, which correlated with indices of sensorimotor

Batch statistical process control of a fluid bed granulation process using in-line spatial filter velocimetry and product temperature measurements.

Science.gov (United States)

Burggraeve, A; Van den Kerkhof, T; Hellings, M; Remon, J P; Vervaet, C; De Beer, T

2011-04-18

Fluid bed granulation is a batch process, which is characterized by the processing of raw materials for a predefined period of time, consisting of a fixed spraying phase and a subsequent drying period. The present study shows the multivariate statistical modeling and control of a fluid bed granulation process based on in-line particle size distribution (PSD) measurements (using spatial filter velocimetry) combined with continuous product temperature registration using a partial least squares (PLS) approach. Via the continuous in-line monitoring of the PSD and product temperature during granulation of various reference batches, a statistical batch model was developed allowing the real-time evaluation and acceptance or rejection of future batches. Continuously monitored PSD and product temperature process data of 10 reference batches (X-data) were used to develop a reference batch PLS model, regressing the X-data versus the batch process time (Y-data). Two PLS components captured 98.8% of the variation in the X-data block. Score control charts in which the average batch trajectory and upper and lower control limits are displayed were developed. Next, these control charts were used to monitor 4 new test batches in real-time and to immediately detect any deviations from the expected batch trajectory. By real-time evaluation of new batches using the developed control charts and by computation of contribution plots of deviating process behavior at a certain time point, batch losses or reprocessing can be prevented. Immediately after batch completion, all PSD and product temperature information (i.e., a batch progress fingerprint) was used to estimate some granule properties (density and flowability) at an early stage, which can improve batch release time. Individual PLS models relating the computed scores (X) of the reference PLS model (based on the 10 reference batches) and the density, respectively, flowabililty as Y-matrix, were developed. The scores of the 4 test

Characterization of the pneumatic behavior of a novel spouted bed apparatus with two adjustable gas inlets

NARCIS (Netherlands)

Gryczka, O.; Heinrich, S.; Miteva, V.; Deen, N.G.; Kuipers, J.A.M.; Jacob, M.; Morl, L.

2008-01-01

Recently the importance of spouted bed technology has significantly increased in the context of drying processes as well as granulation, agglomeration or coating processes. Within this work the fluid dynamics of a novel spouted bed plant with two adjustable gas inlets is investigated. By analysis of

Chemical nature of implant-derived titanium(IV) ions in synovial fluid

International Nuclear Information System (INIS)

Silwood, Christopher J.L.; Grootveld, Martin

2005-01-01

Previous investigations have indicated a deleterious leakage of Ti(III) and/or Ti(IV) species from Ti-Al-V alloy joint prostheses into adjacent tissue, synovium or synovial fluid (SF) in vivo. In view of the importance of the particular chemical nature of such complexes in determining their biological activity, we have employed high field proton ( 1 H) NMR spectroscopy to 'speciate' Ti(IV) in inflammatory SF. Treatment of osteoarthritic SF samples with increasing concentrations of Ti(IV) (0.10-1.03 mM [TiO(C 2 O 4 ) 2 ] 2- ) gave rise to a specific broadening of the citrate proton resonances, indicating that this bioavailable oxygen-donor ligand plays an important role in complexing implant-derived Ti(IV). 1 H NMR analysis of Ti(IV)-loaded SF samples subsequently treated with a large excess of ascorbate (0.05 M) showed that this added Ti(IV) chelator was only poorly effective in removing this metal ion from Ti(IV)-citrate/Ti(IV)-oxycitrate complexes. The results obtained here provide evidence for complexation of the low-molecular-mass (non-protein-bound) fraction of implant-derived Ti(IV) by citrate in vivo

Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies.

Science.gov (United States)

Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

2016-04-01

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m(2)/g), high pore volume (1.23 cm(3)/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

KAUST Repository

Rydé n, Magnus; Lyngfelt, Anders; Mattisson, Tobias

2011-01-01

Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor

Mathematical simulation of hazardous ion retention from radioactive waste in fixed bed reactor

International Nuclear Information System (INIS)

Sohsah, M.A.; Gohneim, M.M.; Othman, S.H.; El-Anadouli, B.E.

2007-01-01

Reactor design for fluid-solid, noncatalytic reaction depends on the prediction of the performance of the reactor kinetically. The most mathematical models used to handle fixed bed reactor in which the solid bed constitute one of the reactants, while a second reactant is in the fluid phase are complex and difficult to handle. A new mathematical model which easier to handle has been developed to describe the system under investigation. The model was examined theoretically and experimentally. A column backed with chelating cloth filter to separate radionuclide form radioactive waste solution is used as a practical application for the model. Comparison of the model predictions with the experimental results gives satisfactory agreement at most of the process stages

Performance of the fixed-bed of granular activated carbon for the removal of pesticides from water supply.

Science.gov (United States)

Alves, Alcione Aparecida de Almeida; Ruiz, Giselle Louise de Oliveira; Nonato, Thyara Campos Martins; Müller, Laura Cecilia; Sens, Maurício Luiz

2018-02-26

The application of a fixed bed adsorption column of granular activated carbon (FBAC-GAC), in the removal of carbaryl, methomyl and carbofuran at a concentration of 25 μg L -1 for each carbamate, from the public water supply was investigated. For the determination of the presence of pesticides in the water supply, the analytical technique of high-performance liquid chromatography with post-column derivatization was used. Under conditions of constant diffusivity, the FBAC-GAC was saturated after 196 h of operation on a pilot scale. The exhaust rate of the granular activated carbon (GAC) in the FBAC-GAC until the point of saturation was 0.02 kg GAC m -3 of treated water. By comparing a rapid small-scale column test and FBAC-GAC, it was confirmed that the predominant intraparticle diffusivity in the adsorption column was constant diffusivity. Based on the results obtained on a pilot scale, it was possible to estimate the values to be applied in the FBAC-GAC (full scale) to remove the pesticides, which are particle size with an average diameter of 1.5 mm GAC; relationship between the internal diameter of the column and the average diameter of GAC ≥50 in order to avoid preferential flow near the adsorption column wall; surface application rate 240 m 3  m -2  d -1 and an empty bed contact time of 3 min. BV: bed volume; CD: constant diffusivity; EBCT: empty bed contact time; FBAC-GAC: fixed bed adsorption column of granular activated carbon; GAC: granular activated carbon; MPV: maximum permitted values; NOM: natural organic matter; PD: proportional diffusivity; pH PCZ : pH of the zero charge point; SAR: surface application rate; RSSCT: rapid small-scale column test; WTCS: water treated conventional system.

Edge instability in incompressible planar active fluids

Science.gov (United States)

Nesbitt, David; Pruessner, Gunnar; Lee, Chiu Fan

2017-12-01

Interfacial instability is highly relevant to many important biological processes. A key example arises in wound healing experiments, which observe that an epithelial layer with an initially straight edge does not heal uniformly. We consider the phenomenon in the context of active fluids. Improving upon the approximation used by Zimmermann, Basan, and Levine [Eur. Phys. J.: Spec. Top. 223, 1259 (2014), 10.1140/epjst/e2014-02189-7], we perform a linear stability analysis on a two-dimensional incompressible hydrodynamic model of an active fluid with an open interface. We categorize the stability of the model and find that for experimentally relevant parameters, fingering instability is always absent in this minimal model. Our results point to the crucial role of density variation in the fingering instability in tissue regeneration.

Multi-sphere unit cell model to calculate the effective thermal conductivity in pebble bed reactors

International Nuclear Information System (INIS)

Van Antwerpen, W.; Rousseau, P.G.; Du Toit, C.G.

2010-01-01

A proper understanding of the mechanisms of heat transfer, fluid flow and pressure drop through a packed bed of spheres is of utmost importance in the design of a high temperature Pebble Bed Reactor (PBR). While the gas flows predominantly in the axial direction through the bed, the total effective thermal conductivity is a lumped parameter that characterises the total heat transfer in the radial direction through the packed bed. The study of the effective thermal conductivity is important because it forms an intricate part of the self-acting decay heat removal chain, which is directly related to the PBR safety case. The effective thermal conductivity is the summation of various heat transport phenomena. These are the enhanced thermal conductivity due to turbulent mixing as the fluid passes through the voids between pebbles, heat transfer due to the movement of the solid spheres and thermal conduction and thermal radiation between the spheres in a stagnant fluid environment. In this study, the conduction and radiation between the spheres are investigated. Firstly, existing correlations for the effective thermal conductivity are investigated, with particular attention given to its applicability in the near-wall region. Several phenomena in particular are examined namely: conduction through the spheres, conduction through the contact area between the spheres, conduction through the gas phase and radiation between solid surfaces. A new approach to simulate the effective thermal conductivity for randomly packed beds is then presented, namely the so-called Multi-sphere Unit Cell Model. The model is validated by comparing the results with that obtained in experiments. (authors)

A randomized, double-blind, crossover comparison of novel continuous bed motion versus traditional bed position whole-body PET/CT imaging

International Nuclear Information System (INIS)

Schatka, Imke; Weiberg, Desiree; Reichelt, Stephanie; Owsianski-Hille, Nicole; Derlin, Thorsten; Berding, Georg; Bengel, Frank M.

2016-01-01

Continuous bed motion has recently been introduced for whole-body PET/CT, and represents a paradigm shift towards individualized and flexible acquisition without the limitations of bed position-based planning. Increased patient comfort due to lack of abrupt table position changes may be another albeit still unproven advantage. For robust clinical implementation, image quality and quantitative accuracy should at least be equal to the prior standard of bed position-based step-and-shoot imaging. The study included 68 consecutive patients referred for whole-body PET/CT for various malignancies. The patients underwent traditional step-and-shoot and novel continuous bed motion acquisition in the same session in a randomized crossover design. The patients and two independent observers were blinded to the sequence of scan techniques. Patient comfort/satisfaction was examined using a standardized questionnaire. SUVs were compared for reference tissue (liver, muscle) and tumour lesions. PET image quality and misalignment with CT images were evaluated on a scale of 1 - 4. Patients preferred continuous bed motion over step-and-shoot (P = 0.0001). It was considered to be more relaxing (38 % vs. 8 %), quieter (34 % vs. 8 %), and more fluid (64 % vs. 8 %). Image quality, SUV and CT misalignment did not differ between the techniques. Continuous bed motion resulted in better end-plane image quality (P < 0.0001). Regardless of the technique, second examinations had significantly higher tumour lesion SUVmax values (P = 0.0002), and a higher CT misalignment score (P = 0.0017). Oncological PET/CT with continuous bed motion enhances patient comfort and is associated with image quality at least comparable to that with traditional bed position-based step-and-shoot acquisition. (orig.)

A randomized, double-blind, crossover comparison of novel continuous bed motion versus traditional bed position whole-body PET/CT imaging

Energy Technology Data Exchange (ETDEWEB)

Schatka, Imke [Hannover Medical School, Department of Nuclear Medicine, Hannover (Germany); Charite, Department of Nuclear Medicine, Berlin (Germany); Weiberg, Desiree; Reichelt, Stephanie; Owsianski-Hille, Nicole; Derlin, Thorsten; Berding, Georg; Bengel, Frank M. [Hannover Medical School, Department of Nuclear Medicine, Hannover (Germany)

2016-04-15

Continuous bed motion has recently been introduced for whole-body PET/CT, and represents a paradigm shift towards individualized and flexible acquisition without the limitations of bed position-based planning. Increased patient comfort due to lack of abrupt table position changes may be another albeit still unproven advantage. For robust clinical implementation, image quality and quantitative accuracy should at least be equal to the prior standard of bed position-based step-and-shoot imaging. The study included 68 consecutive patients referred for whole-body PET/CT for various malignancies. The patients underwent traditional step-and-shoot and novel continuous bed motion acquisition in the same session in a randomized crossover design. The patients and two independent observers were blinded to the sequence of scan techniques. Patient comfort/satisfaction was examined using a standardized questionnaire. SUVs were compared for reference tissue (liver, muscle) and tumour lesions. PET image quality and misalignment with CT images were evaluated on a scale of 1 - 4. Patients preferred continuous bed motion over step-and-shoot (P = 0.0001). It was considered to be more relaxing (38 % vs. 8 %), quieter (34 % vs. 8 %), and more fluid (64 % vs. 8 %). Image quality, SUV and CT misalignment did not differ between the techniques. Continuous bed motion resulted in better end-plane image quality (P < 0.0001). Regardless of the technique, second examinations had significantly higher tumour lesion SUVmax values (P = 0.0002), and a higher CT misalignment score (P = 0.0017). Oncological PET/CT with continuous bed motion enhances patient comfort and is associated with image quality at least comparable to that with traditional bed position-based step-and-shoot acquisition. (orig.)

Fluidized bed volume reduction of diverse radwastes

International Nuclear Information System (INIS)

McFee, J.N.; McConnell, J.W.; Waddoups, D.A.; Gray, M.F.; Harwood, L.E.; Clayton, N.J.; Drown, D.C.

1981-01-01

Method and apparatus for a fluidized bed radwaste volume reduction system are claimed. Low level radioactive wastes, combustible solids, ion exchange resins and filter sludges, and liquids, emanating from a reactor facility are introduced separately through an integrated waste influent system into a common fluidized bed vessel where volume reduction either through incineration or calcination occurs. Addition of a substance to the ion exchange resin before incineration inhibits the formation of low-melting point materials which tend to form clinkers in the bed. Solid particles are scrubbed or otherwise removed from the gaseous effluent of the vessel in an off-gas system, before the cooled and cleaned off-gas is released to the atmosphere. Iodine is chemically or physically removed from the off-gas. Otherwise, the only egress materials from the volume reduction system are containerized dry solids and tramp material. The bed material used during each mode may be circulated, cleaned, stored and exchanged from within the bed vessel by use of a bed material handling system. An instrumentation and control system provides operator information, monitors performance characteristics, implements start up and shut down procedures, and initiates alarms and emergency procedures during abnormal conditions

CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(II)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

Institute of Scientific and Technical Information of China (English)

2008-01-01

Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.

Multivariate statistical process control of a continuous pharmaceutical twin-screw granulation and fluid bed drying process.

Science.gov (United States)

Silva, A F; Sarraguça, M C; Fonteyne, M; Vercruysse, J; De Leersnyder, F; Vanhoorne, V; Bostijn, N; Verstraeten, M; Vervaet, C; Remon, J P; De Beer, T; Lopes, J A

2017-08-07

A multivariate statistical process control (MSPC) strategy was developed for the monitoring of the ConsiGma™-25 continuous tablet manufacturing line. Thirty-five logged variables encompassing three major units, being a twin screw high shear granulator, a fluid bed dryer and a product control unit, were used to monitor the process. The MSPC strategy was based on principal component analysis of data acquired under normal operating conditions using a series of four process runs. Runs with imposed disturbances in the dryer air flow and temperature, in the granulator barrel temperature, speed and liquid mass flow and in the powder dosing unit mass flow were utilized to evaluate the model's monitoring performance. The impact of the imposed deviations to the process continuity was also evaluated using Hotelling's T 2 and Q residuals statistics control charts. The influence of the individual process variables was assessed by analyzing contribution plots at specific time points. Results show that the imposed disturbances were all detected in both control charts. Overall, the MSPC strategy was successfully developed and applied. Additionally, deviations not associated with the imposed changes were detected, mainly in the granulator barrel temperature control. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of computational fluid dynamics for the simulation of cryogenic molecular sieve bed absorber of hydrogen isotopes recovery system for Indian LLCB-TBM

Energy Technology Data Exchange (ETDEWEB)

Gayathri Devi, V.; Sircar, A.; Sarkar, B. [Institute of Plasma Research, Bhat, Gandhinagar, Gujarar (India)

2015-03-15

One of the most challenging tasks in the design of the fuel cycle system lies in the effective design of Tritium Extraction System (TES) which involves proper extraction and purification of tritium in the fuel cycle of the fusion reactor. Indian Lead Lithium cooled Ceramic Breeder Test Blanket Module (LLCB-TBM) would extract hydrogen isotopes through Cryogenic Molecular Sieve Bed (CMSB) adsorber system. A prototype Hydrogen Isotopes Recovery System (HIRS) is being developed to validate the concepts for tritium extraction by adsorption mass transfer mechanism. In this study, a design model has been developed and analyzed to simulate the adsorption mass transfer kinetics in a fixed bed adsorption column. The simulation leads primarily to effective design of HIRS, which is a state-of-the-art technology. The paper describes the process simulation approach and the results of Computational Fluid Dynamics (CFD) analysis. The effects of different operating conditions are studied to investigate their influence on the hydrogen isotopes adsorption capacity. The results of the present simulation study would be used to understand the best optimized transport phenomenon before realizing the TES as a system for LLCB-TBM. (authors)

Thermal-hydraulic analysis techniques for axisymmetric pebble bed nuclear reactor cores

International Nuclear Information System (INIS)

Stroh, K.R.

1979-03-01

The pebble bed reactor's cylindrical core volume contains a random bed of small, spherical fuel-moderator elements. These graphite spheres, containing a central region of dispersed coated-particle fissile and fertile material, are cooled by high pressure helium flowing through the connected interstitial voids. A mathematical model and numerical solution technique have been developed which allow calculation of macroscopic values of thermal-hydraulic variables in an axisymmetric pebble bed nuclear reactor core. The computer program PEBBLE is based on a mathematical model which treats the bed macroscopically as a generating, conducting porous medium. The steady-state model uses a nonlinear Forchheimer-type relation between the coolant pressure gradient and mass flux, with newly derived coefficients for the linear and quadratic resistance terms. The remaining equations in the model make use of mass continuity, and thermal energy balances for the solid and fluid phases

Study of the fluidized bed chemical vapor deposition process on very dense powder for nuclear applications

International Nuclear Information System (INIS)

Vanni, Florence

2015-01-01

This thesis is part of the development of low-enriched nuclear fuel, for the Materials Test Reactors (MTRs), constituted of uranium-molybdenum particles mixed with an aluminum matrix. Under certain conditions under irradiations, the U(Mo) particles interact with the aluminum matrix, causing unacceptable swelling of the fuel plate. To inhibit this phenomenon, one solution consists in depositing on the surface of the U(Mo) particles, a thin silicon layer to create a barrier effect. This thesis has concerned the study of the fluidized bed chemical vapor deposition (CVD) process to deposit silicon from silane, on the U(Mo) powder, which has an exceptional density of 17,500 kg/m 3 . To achieve this goal, two axes were treated during the thesis: the study and the optimization of the fluidization of a so dense powder, and then those of the silicon deposition process. For the first axis, a series of tests was performed on a surrogate tungsten powder in different columns made of glass and made of steel with internal diameters ranging from 2 to 5 cm, at room temperature and at high temperature (650 C) close to that of the deposits. These experiments helped to identify wall effects phenomena within the fluidized bed, which can lead to heterogeneous deposits or particles agglomeration. Some dimensions of the fluidization columns and operating conditions allowing a satisfactory fluidization of the powder were identified, paving the way for the study of silicon deposition. Several campaigns of deposition experiments on the surrogate powder and then on the U(Mo) powder were carried out in the second axis of the study. The influence of the bed temperature, the inlet molar fraction of silane diluted in argon, and the total gas flow of fluidization, was examined for different diameters of reactor and for various masses of powder. Morphological and structural characterization analyses (SEM, XRD..) revealed a uniform silicon deposition on all the powder and around each particle

Linking algal growth inhibition to chemical activity

DEFF Research Database (Denmark)

Schmidt, Stine N.; Mayer, Philipp

Unitless chemical activity, expressing the energetic level of a compound relative to its energetic level in pure liquid [0-1], has proven useful to quantify the effective exposure to hydrophobic organic compounds through both aerial and aqueous media. Several studies have linked toxicity to chemi......Unitless chemical activity, expressing the energetic level of a compound relative to its energetic level in pure liquid [0-1], has proven useful to quantify the effective exposure to hydrophobic organic compounds through both aerial and aqueous media. Several studies have linked toxicity...... to chemical activity, as opposed to e.g. the total concentration. Baseline toxicity (narcosis) for neutral hydrophobic organic compounds has been shown to initiate in the narrow chemical activity range of 0.01 to 0.1. This presentation focuses on linking algal growth inhibition to chemical activity......-polar liquids were applied to challenge the chemical activity range for baseline toxicity. For each compound, the effective activity (Ea50) was estimated as the ratio of the effective concentration (EC50) and water solubility. Of these ratios, 90% were within the expected chemical activity range of 0.01 to 0...

Formation of early-middle Miocene red beds in the South China Sea: element geochemistry and mineralogy analysis

Science.gov (United States)

Lyu, X.; Liu, Z.

2017-12-01

The formation of oceanic red beds that usually present oxic and oligotrophic conditions with low sedimentation rate has been used to trace depositional paleoenvironment and paleoclimate change. Red beds overlying oceanic basalts were drilled at two adjacent Sites U1433 and U1434 of IODP Expedition 349 in the Southwest Subbasin of the South China Sea. The occurrence of early-middle Miocene red beds may indicate that at that time there was oxic and quiet marine environment in the deep South China Sea. To understand their formation of red-color, local depositional condition, and potential paleoceanographic significance, major elements (XRF), trace and rare earth elements (ICP-MS), Fe chemical speciation (modified sequential iron extraction procedure), and Fe oxic minerals (CBD and DRS) were analyzed. Geochemical and mineralogical data reveal that hematite and goethite are responsible for the reddish color and red beds were deposited under highly oxic, oligotrophic conditions with a little later hydrothermal influence in the South China Sea. Our results indicate that: (1) after treatment using the CBD procedure, the red samples presented a change in color to greenish, showing the iron oxides being responsible for the sediment color; (2) enriched Mn, depleted U, S enrichment factors, and negative Ce anomaly show that the water mass was pre-oxidized before transported to the study location; (3) low primary productivity was inferred from the lower P, Ba enrichment factors in red beds compared to non-red beds; (4) the excess Mo influx at the bottom may come from the later hydrothermal input; (5) the diverse Ca enrichment factors and correlations between Fe and Al suggest different allogenic sources for red beds at our two sites. We conclude that the red beds at Sites U1433 and U1434 despite their diverse sources both developed in externally oxidized water mass and low primary productivity conditions, and partially altered by hydrothermal fluids after their pelagic

Proposed replacement and operation of the anhydrous hydrogen fluoride supply and fluidized-bed chemical processing systems at Building 9212, Y-12 Plant, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

1995-09-01

The US Department of Energy (DOE) proposes to replace the existing anhydrous hydrogen fluoride (AHF) supply and fluidized-bed reactor systems for the Weapons Grade Highly Enriched Uranium Chemical Recovery and Recycle Facility, Building 9212, which is located within the Y-12 Plant on DOE's Oak Ridge Reservation in Oak Ridge, Tennessee. The proposed replacement system would be based upon modern design criteria and safety analyses. The replacement AHF supply and distribution system equipment would be located on the existing Dock 8/8A at Building 9212. Utilities would be extended to the dock to service the process equipment. The following process equipment modules would be prefabricated for installation at the modified dock: an AHF cylinder enclosure, an AHF supply manifold and vaporizer module, an AHF sump tank and transfer skid, and an AHF supply off-gas scrubber assembly module. The fluidized-bed reactor system would be constructed in an area adjacent to the existing system in Building 9212. The replacement equipment would consist of a new reduction fluidized-bed reactor, a hydrofluorination fluidized-bed reactor, and associated air emission control equipment. The no-action alternative, which is the continued operation of the existing AHF supply and fluidized-bed reactor systems, was also evaluated

Flow and fracture in water-saturated, unconstrained granular beds

Directory of Open Access Journals (Sweden)

Germán eVaras

2015-06-01

Full Text Available The injection of gas in a liquid-saturated granular bed gives rise to a wide variety of invasion patterns. Many studies have focused on constrained porous media, in which the grains are fixed in the bed and only the interstitial fluid flows when the gas invades the system. With a free upper boundary, however, the grains can be entrained by the ascending gas or fluid motion, and the competition between the upward motion of grains and sedimentation leads to new patterns. We propose a brief review of the experimental investigation of the dynamics of air rising through a water-saturated, unconstrained granular bed, in both two and three dimensions. After describing the invasion pattern at short and long time, a tentative regime-diagram is proposed. We report original results showing a dependence of the fluidized zone shape, at long times, on the injection flow rate and grain size. A method based on image analysis makes it possible to detect not only the fluidized zone profile in the stationary regime, but also to follow the transient dynamics of its formation. Finally, we describe the degassing dynamics inside the fluidized zone, in the stationary regime. Depending on the experimental conditions, regular bubbling, continuous degassing, intermittent regime or even spontaneous flow-to-fracture transition are observed.

Overview of Chronic Oral Toxicity Values for Chemicals Present in Hydraulic Fracturing Fluids, Flowback and Produced Waters

Science.gov (United States)

as part of EPA's Hydraulic Fracturing Drinking Water Assessment, EPA is summarizing existing toxicity data for chemicals reported to be used in hydraulic fracturing fluids and/or found in flowback or produced waters from hydraulically fractured wells

Interaction of slurry pipe flow with a stationary bed

Czech Academy of Sciences Publication Activity Database

Matoušek, Václav

2007-01-01

Roč. 107, č. 6 (2007), s. 365-372 ISSN 0038-223X R&D Projects: GA ČR GA103/06/0428 Institutional research plan: CEZ:AV0Z20600510 Keywords : sheet flow * particle dispersion * suspension * concentration profile * bed shear stress Subject RIV: BK - Fluid Dynamics Impact factor: 0.108, year: 2007

Active Learning in Fluid Mechanics: Youtube Tube Flow and Puzzling Fluids Questions

Science.gov (United States)

Hrenya, Christine M.

2011-01-01

Active-learning exercises appropriate for a course in undergraduate fluid mechanics are presented. The first exercise involves an experiment in gravity-driven tube flow, with small groups of students partaking in a contest to predict the experimental flow rates using the mechanical energy balance. The second exercise takes the form of an…

Application of CaO-Based Bed Material for Dual Fluidized Bed Steam Biomass Gasification

Science.gov (United States)

Koppatz, S.; Pfeifer, C.; Kreuzeder, A.; Soukup, G.; Hofbauer, H.

Gasification of biomass is a suitable option for decentralized energy supply based on renewable sources in the range of up to 50 MW fuel input. The paper presents the dual fluidized bed (DFB) steam gasification process, which is applied to generate high quality and nitrogen-free product gas. Essential part of the DFB process is the bed material used in the fluidized reactors, which has significant impact on the product gas quality. By the use of catalytically active bed materials the performance of the overall process is increased, since the bed material favors reactions of the steam gasification. In particular, tar reforming reactions are favored. Within the paper, the pilot plant based on the DFB process with 100kW fuel input at Vienna University of Technology, Austria is presented. Actual investigations with focus on CaO-based bed materials (limestone) as well as with natural olivine as bed material were carried out at the pilot plant. The application of CaO-based bed material shows mainly decreased tar content in the product gas in contrast to experiments with olivine as bed material. The paper presents the results of steam gasification experiments with limestone and olivine, whereby the product gas composition as well as the tar content and the tar composition are outlined.

The odorant receptor co-receptor from the bed bug, Cimex lectularius L.

Directory of Open Access Journals (Sweden)

Immo A Hansen

Full Text Available Recently, the bed bug, Cimex lectularius L. has re-emerged as a serious and growing problem in many parts of the world. Presence of resistant bed bugs and the difficulty to eliminate them has renewed interest in alternative control tactics. Similar to other haematophagous arthropods, bed bugs rely on their olfactory system to detect semiochemicals in the environment. Previous studies have morphologically characterized olfactory organs of bed bugs' antenna and have physiologically evaluated the responses of olfactory receptor neurons (ORNs to host-derived chemicals. To date, odorant binding proteins (OBPs and odorant receptors (ORs associated with these olfaction processes have not been studied in bed bugs. Chemoreception in insects requires formation of heteromeric complexes of ORs and a universal OR coreceptor (Orco. Orco is the constant chain of every odorant receptor in insects and is critical for insect olfaction but does not directly bind to odorants. Orco agonists and antagonists have been suggested as high-value targets for the development of novel insect repellents. In this study, we have performed RNAseq of bed bug sensory organs and identified several odorant receptors as well as Orco. We characterized Orco expression and investigated the effect of chemicals targeting Orco on bed bug behavior and reproduction. We have identified partial cDNAs of six C. lectularius OBPs and 16 ORs. Full length bed bug Orco was cloned and sequenced. Orco is widely expressed in different parts of the bed bug including OR neurons and spermatozoa. Treatment of bed bugs with the agonist VUAA1 changed bed bug pheromone-induced aggregation behavior and inactivated spermatozoa. We have described and characterized for the first time OBPs, ORs and Orco in bed bugs. Given the importance of these molecules in chemoreception of this insect they are interesting targets for the development of novel insect behavior modifiers.

Effects of pressure drop and superficial velocity on the bubbling fluidized bed incinerator.

Science.gov (United States)

Wang, Feng-Jehng; Chen, Suming; Lei, Perng-Kwei; Wu, Chung-Hsing

2007-12-01

Since performance and operational conditions, such as superficial velocity, pressure drop, particles viodage, and terminal velocity, are difficult to measure on an incinerator, this study used computational fluid dynamics (CFD) to determine numerical solutions. The effects of pressure drop and superficial velocity on a bubbling fluidized bed incinerator (BFBI) were evaluated. Analytical results indicated that simulation models were able to effectively predict the relationship between superficial velocity and pressure drop over bed height in the BFBI. Second, the models in BFBI were simplified to simulate scale-up beds without excessive computation time. Moreover, simulation and experimental results showed that minimum fluidization velocity of the BFBI must be controlled in at 0.188-3.684 m/s and pressure drop was mainly caused by bed particles.

Chemical Technology Division annual technical report, 1994

International Nuclear Information System (INIS)

1995-06-01

Highlights of the Chemical Technology (CMT) Division's activities during 1994 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion; (3) methods for treatment of hazardous waste and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from waste streams, concentrating radioactive waste streams with advanced evaporator technology, and producing 99 Mo from low-enriched uranium for medical applications; (6) electrometallurgical treatment of the many different types of spent nuclear fuel in storage at Department of Energy sites; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, and impurities in scrap copper and steel; and the geochemical processes involved in mineral/fluid interfaces and water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL)

Relationships between sea-bed radionuclide activities and some sedimentological variables

International Nuclear Information System (INIS)

Ligero, R.A.; Ramos-Lerate, I.; Barrera, M.; Casas-Ruiz, M.

2001-01-01

Natural radionuclides ( 232 Th, 226 Ra, 40 K) and 137 Cs, coming from atmospheric radioactive fallout, have been measured in sea-bed sediments of the Bay of Cadiz (South Western Spain). In this report, multivariate analysis methods have been employed to study the relationships between the activities of the radionuclides and some sedimentological variables like granulometric facies, organic content and apparent density. The correlation functions found show that it is possible to determine, with a satisfactory degree of approximation, the granulometric facies of the sediments using only radiometric information

Modeling of reaction kinetics in bubbling fluidized bed biomass gasification reactor

Energy Technology Data Exchange (ETDEWEB)

Thapa, R.K.; Halvorsen, B.M. [Telemark University College, Kjolnes ring 56, P.O. Box 203, 3901 Porsgrunn (Norway); Pfeifer, C. [University of Natural Resources and Life Sciences, Vienna (Austria)

2013-07-01

Bubbling fluidized beds are widely used as biomass gasification reactors as at the biomass gasification plant in Gussing, Austria. The reactor in the plant is a dual circulating bubbling fluidized bed gasification reactor. The plant produces 2MW electricity and 4.5MW heat from the gasification of biomass. Wood chips as biomass and olivine particles as hot bed materials are fluidized with high temperature steam in the reactor. As a result, biomass undergoes endothermic chemical reaction to produce a mixture of combustible gases in addition to some carbon-dioxide (CO2). The combustible gases are mainly hydrogen (H2), carbon monoxide (CO) and methane (CH4). The gas is used to produce electricity and heat via utilization in a gas engine. Alternatively, the gas is further processed for gaseous or liquid fuels, but still on the process of development level. Composition and quality of the gas determine the efficiency of the reactor. A computational model has been developed for the study of reaction kinetics in the gasification rector. The simulation is performed using commercial software Barracuda virtual reactor, VR15. Eulerian-Lagrangian approach in coupling of gas-solid flow has been implemented. Fluid phase is treated with an Eulerian formulation. Discrete phase is treated with a Lagrangian formulation. Particle-particle and particle-wall interactions and inter-phase heat and mass transfer have been taken into account. Series of simulations have been performed to study model prediction of the gas composition. The composition is compared with data from the gasifier at the CHP plant in Güssing, Austria. The model prediction of the composition of gases has good agreements with the result of the operating plant.

Supercritical fluids processing: emerging opportunities

International Nuclear Information System (INIS)

Kovaly, K.A.

1985-01-01

This publication on the emerging opportunities of supercritical fluids processing reveals the latest research findings and development trends in this field. These findings and development trends are highlighted, and the results of applications of technology to the business of supercritical fluids are reported. Applications of supercritical fluids to chemical intermediates, environmental applications, chemical reactions, food and biochemistry processing, and fuels processing are discussed in some detail

Application of positron emission tomography to particulate flow measurement in chemical engineering processes

International Nuclear Information System (INIS)

Bemrose, C.R.; Fowles, P.; Hawkesworth, M.R.; O'Dwyer, M.A.

1988-01-01

Many chemical engineering processes involve the motion of fluids or particulate solids in bulk, and a detailed knowledge of the flow characteristics is important to their efficient and reliable operation. Initial results on the application of PET to fluidized bed studies are reported. Because back-projection image reconstruction strategies are prohibitively inefficient for locating moving single labelled particles, a new technique has been developed based on the closest approach of photon trajectories to give the most probable position. Investigations involving a single particle moving in a known manner have been used to analyse the camera performance and a preliminary relationship between uncertainty and source location is described. To supplement the normal graphical presentation of results, a new animated colour display system has been developed and used to observe for the first time particle motion within a fluidized bed. (orig.)

CFD Activity at Aerojet Related to Seals and Fluid Film Bearing

Science.gov (United States)

Bache, George E.

1991-01-01

Computational Fluid Dynamics (CFD) activities related to seals and fluid film bearings are presented. Among the topics addressed are the following: Aerovisc Numeric and its capabilities; Recent Seal Applications; and Future Code Developments.

[The criterion prognostic significance of examinations of chemiluminescence of oral fluid under impact of chemical pollutants of manufacture of rubber and rubber technical production].

Science.gov (United States)

Galiullina, E F; Valiev, A v; Kamilov, R F; Shakirov, D F; Buliakov, P T

2013-12-01

The article presents the results of studies concerning the effect of unfavorable factors of chemical nature on fluid of oral cavity among workers of the Ufa plant of elastomer materials, articles and structures. It is established that in persons contacting with chemical pollutants of manufacture of rubber and rubber technical production the indicators of chemiluminescence of saliva fluid are significantly expressed and depend on professional standing.

Chemical composition and antioxidant/antimicrobial activities in supercritical carbon dioxide fluid extract of Gloiopeltis tenax.

Science.gov (United States)

Zheng, Jiaojiao; Chen, Yicun; Yao, Fen; Chen, Weizhou; Shi, Ganggang

2012-12-01

Gloiopeltis tenax (G. tenax) is widely distributed along the Chinese coastal areas and is commonly used in the treatment of diarrhea and colitis. This study aimed at investigating the bioactivities of the volatile constituents in G. tenax. We extracted the essential constituents of G. tenax by supercritical carbon dioxide extraction (CO₂-SFE), then identified and analyzed the constituents by gas chromatography-mass spectrometry (GC-MS). In total, 30 components were identified in the G. tenax extract. The components showed remarkable antioxidant activity (radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH)), lipid peroxidation inhibition capacity (in a β-carotene/linoleic acid-coupled oxidation reaction), and hydroxyl radical-scavenging activity (by deoxyribose degradation by iron-dependent hydroxyl radical), compared to butylated hydroxytoluene. In microdilution assays, G. tenax extracts showed a moderate inhibitory effects on Staphyloccocus aureus (minimum inhibitory concentration (MIC) = 3.9 mg/mL), Enterococcus faecalis (7.8 mg/mL), Pseudomonas aeruginosa (15.6 mg/mL), and Escherichia coli (3.9 mg/mL). Antioxidant and antimicrobial activities of G. tenax were related to the active chemical composition. These results suggest that the CO₂-SFE extract from G. tenax has potential to be used as a natural antioxidant and antimicrobial agent in food processing.

Chemical Composition and Antioxidant/Antimicrobial Activities in Supercritical Carbon Dioxide Fluid Extract of Gloiopeltis tenax

Directory of Open Access Journals (Sweden)

Jiaojiao Zheng

2012-11-01

Full Text Available Gloiopeltis tenax (G. tenax is widely distributed along the Chinese coastal areas and is commonly used in the treatment of diarrhea and colitis. This study aimed at investigating the bioactivities of the volatile constituents in G. tenax. We extracted the essential constituents of G. tenax by supercritical carbon dioxide extraction (CO2-SFE, then identified and analyzed the constituents by gas chromatography-mass spectrometry (GC-MS. In total, 30 components were identified in the G. tenax extract. The components showed remarkable antioxidant activity (radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH, lipid peroxidation inhibition capacity (in a β-carotene/linoleic acid-coupled oxidation reaction, and hydroxyl radical-scavenging activity (by deoxyribose degradation by iron-dependent hydroxyl radical, compared to butylated hydroxytoluene. In microdilution assays, G. tenax extracts showed a moderate inhibitory effects on Staphyloccocus aureus (minimum inhibitory concentration (MIC = 3.9 mg/mL, Enterococcus faecalis (7.8 mg/mL, Pseudomonas aeruginosa (15.6 mg/mL, and Escherichia coli (3.9 mg/mL. Antioxidant and antimicrobial activities of G. tenax were related to the active chemical composition. These results suggest that the CO2-SFE extract from G. tenax has potential to be used as a natural antioxidant and antimicrobial agent in food processing.

Fluidized-Bed Coating with Sodium Sulfate and PVA-TiO2, 1. Review and Agglomeration Regime Maps

DEFF Research Database (Denmark)

Hede, Peter Dybdahl; Bach, Poul; Jensen, Anker Degn

2009-01-01

-TiO2. The coating experiments were conducted in a medium-scale top-spray MP-1 fluid bed, and many rheological experiments were performed on the coating formulations to support the interpretation of the fluid-bed coating results. In this first part of the study, a thorough introduction to the inorganic...... salt and polymer film coating is provided, along with a presentation of the equipment and materials being used in this and the following papers. Results from agglomeration studies over a broad range of process conditions are presented, showing that the tendency toward agglomeration is always less...

Numerical simulation of non-conventional liquid fuels feeding in a bubbling fluidized bed combustor

Directory of Open Access Journals (Sweden)

Mladenović Milica R.

2013-01-01

Full Text Available The paper deals with the development of mathematical models for detailed simulation of lateral jet penetration into the fluidized bed (FB, primarily from the aspect of feeding of gaseous and liquid fuels into FB furnaces. For that purpose a series of comparisons has been performed between the results of in-house developed procedure- fluid-porous medium numerical simulation of gaseous jet penetration into the fluidized bed, Fluent’s two-fluid Euler-Euler FB simulation model, and experimental results (from the literature of gaseous jet penetration into the 2D FB. The calculation results, using both models, and experimental data are in good agreement. The developed simulation procedures of jet penetration into the FB are applied to the analysis of the effects, which are registered during the experiments on a fluidized pilot furnace with feeding of liquid waste fuels into the bed, and brief description of the experiments is also presented in the paper. Registered effect suggests that the water in the fuel improved mixing of fuel and oxidizer in the FB furnace, by increasing jet penetration into the FB due to sudden evaporation of water at the entry into the furnace. In order to clarify this effect, numerical simulations of jet penetration into the FB with three-phase systems: gas (fuel, oxidizer, and water vapour, bed particles and water, have been carried out. [Projekat Ministarstva nauke Republike Srbije, br. TR33042: Improvement of the industrial fluidized bed facility, in scope of technology for energy efficient and environmentally feasible combustion of various waste materials in the fluidized bed

Fluidized bed steam reformed mineral waste form performance testing to support Hanford Supplemental Low Activity Waste Immobilization Technology Selection

Energy Technology Data Exchange (ETDEWEB)

Jantzen, C. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pierce, E. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bannochie, C. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Burket, P. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Cozzi, A. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Crawford, C. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fox, K. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Herman, C. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Miller, D. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Missimer, D. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Nash, C. A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Williams, M. F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Brown, C. F. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qafoku, N. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Neeway, J. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Valenta, M. M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, G. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Swanberg, D. J. [Washington River Protection Solutions (WRPS), Richland, WA (United States); Robbins, R. A. [Washington River Protection Solutions (WRPS), Richland, WA (United States); Thompson, L. E. [Washington River Protection Solutions (WRPS), Richland, WA (United States)

2015-10-01

This report describes the benchscale testing with simulant and radioactive Hanford Tank Blends, mineral product characterization and testing, and monolith testing and characterization. These projects were funded by DOE EM-31 Technology Development & Deployment (TDD) Program Technical Task Plan WP-5.2.1-2010-001 and are entitled “Fluidized Bed Steam Reformer Low-Level Waste Form Qualification”, Inter-Entity Work Order (IEWO) M0SRV00054 with Washington River Protection Solutions (WRPS) entitled “Fluidized Bed Steam Reforming Treatability Studies Using Savannah River Site (SRS) Low Activity Waste and Hanford Low Activity Waste Tank Samples”, and IEWO M0SRV00080, “Fluidized Bed Steam Reforming Waste Form Qualification Testing Using SRS Low Activity Waste and Hanford Low Activity Waste Tank Samples”. This was a multi-organizational program that included Savannah River National Laboratory (SRNL), THOR® Treatment Technologies (TTT), Pacific Northwest National Laboratory (PNNL), Oak Ridge National Laboratory (ORNL), Office of River Protection (ORP), and Washington River Protection Solutions (WRPS). The SRNL testing of the non-radioactive pilot-scale Fluidized Bed Steam Reformer (FBSR) products made by TTT, subsequent SRNL monolith formulation and testing and studies of these products, and SRNL Waste Treatment Plant Secondary Waste (WTP-SW) radioactive campaign were funded by DOE Advanced Remediation Technologies (ART) Phase 2 Project in connection with a Work-For-Others (WFO) between SRNL and TTT.

Process fluid cooling system

International Nuclear Information System (INIS)

Farquhar, N.G.; Schwab, J.A.

1977-01-01

A system of heat exchangers is disclosed for cooling process fluids. The system is particularly applicable to cooling steam generator blowdown fluid in a nuclear plant prior to chemical purification of the fluid in which it minimizes the potential of boiling of the plant cooling water which cools the blowdown fluid

Flocking from a quantum analogy: spin-orbit coupling in an active fluid

Science.gov (United States)

Loewe, Benjamin; Souslov, Anton; Goldbart, Paul M.

2018-01-01

Systems composed of strongly interacting self-propelled particles can form a spontaneously flowing polar active fluid. The study of the connection between the microscopic dynamics of a single such particle and the macroscopic dynamics of the fluid can yield insights into experimentally realizable active flows, but this connection is well understood in only a few select cases. We introduce a model of self-propelled particles based on an analogy with the motion of electrons that have strong spin-orbit coupling. We find that, within our model, self-propelled particles are subject to an analog of the Heisenberg uncertainty principle that relates translational and rotational noise. Furthermore, by coarse-graining this microscopic model, we establish expressions for the coefficients of the Toner-Tu equations—the hydrodynamic equations that describe an active fluid composed of these ‘active spins.’ The connection between stochastic self-propelled particles and quantum particles with spin may help realize exotic phases of matter using active fluids via analogies with systems composed of strongly correlated electrons.

Instabilities and diffusion in a hydrodynamic model of a fluid membrane coupled to a thin active fluid layer.

Science.gov (United States)

Sarkar, N; Basu, A

2012-11-01

We construct a coarse-grained effective two-dimensional (2d hydrodynamic theory as a theoretical model for a coupled system of a fluid membrane and a thin layer of a polar active fluid in its ordered state that is anchored to the membrane. We show that such a system is prone to generic instabilities through the interplay of nonequilibrium drive, polar order and membrane fluctuation. We use our model equations to calculate diffusion coefficients of an inclusion in the membrane and show that their values depend strongly on the system size, in contrast to their equilibrium values. Our work extends the work of S. Sankararaman and S. Ramaswamy (Phys. Rev. Lett., 102, 118107 (2009)) to a coupled system of a fluid membrane and an ordered active fluid layer. Our model is broadly inspired by and should be useful as a starting point for theoretical descriptions of the coupled dynamics of a cell membrane and a cortical actin layer anchored to it.

Design of particle bed reactors for the space nuclear thermal propulsion program

International Nuclear Information System (INIS)

Ludewig, H.; Powell, J.R.; Todosow, M.; Maise, G.; Barletta, R.; Schweitzer, D.G.

1996-01-01

This paper describes the design for the Particle Bed Reactor (PBR) that was considered for the Space Nuclear Thermal Propulsion (SNTP) Program. The methods of analysis and their validation are outlined first. Monte Carlo methods were used for the physics analysis, several new algorithms were developed for the fluid dynamics, heat transfer and transient analysis; and commercial codes were used for the stress analysis. We carried out a critical experiment, prototypic of the PBR to validate the reactor physics; blowdown experiments with beds of prototypic dimensions were undertaken to validate the power-extraction capabilities from particle beds. In addition, materials and mechanical design concepts for the fuel elements were experimentally validated. (author)

Feasibility study - Lowered bed temperature in Fluidised Bed boilers for waste; Foerstudie - Saenkt baeddtemperatur i FB-pannor foer avfallsfoerbraenning

Energy Technology Data Exchange (ETDEWEB)

Niklasson, Fredrik

2009-01-15

constant O{sub 2} concentration in the flue gas, the emissions of CO were unaffected by changed ratios of air and recycled flue gas to reduce the bed temperature. However, the emissions of NO{sub x} tended to increase due to raised temperatures of about 40 deg C at the top of the furnace at maximum load. When increasing the amount of recycled flue gas to the bed, the concentration of oxygen is reduced and its implications upon the chemistry in the bed and possible accumulation of unburned fuel have not been investigated due to the short experimental period. Chemical analysis of sand from the bed showed that the concentration of chlorides in the sand increased more that 4 times after 30 hours of operation at reduced bed temperatures. This finding indicates that the chemical balance in the bed is significantly altered when the temperature is reduced. To determine the consequences for the operation of the boiler, further experiments and measurements that are more extensive are necessary. No measurable changes of alkali contents in the sand were observed.

Late Noachian fluvial erosion on Mars: Cumulative water volumes required to carve the valley networks and grain size of bed-sediment

Science.gov (United States)

Rosenberg, Eliott N.; Head, James W., III

2015-11-01

Our goal is to quantify the cumulative water volume that was required to carve the Late Noachian valley networks on Mars. We employ an improved methodology in which fluid/sediment flux ratios are based on empirical data, not assumed. We use a large quantity of data from terrestrial rivers to assess the variability of actual fluid/sediment flux sediment ratios. We find the flow depth by using an empirical relationship to estimate the fluid flux from the estimated channel width, and then using estimated grain sizes (theoretical sediment grain size predictions and comparison with observations by the Curiosity rover) to find the flow depth to which the resulting fluid flux corresponds. Assuming that the valley networks contained alluvial bed rivers, we find, from their current slopes and widths, that the onset of suspended transport occurs near the sand-gravel boundary. Thus, any bed sediment must have been fine gravel or coarser, whereas fine sediment would be carried downstream. Subsequent to the cessation of fluvial activity, aeolian processes have partially redistributed fine-grain particles in the valleys, often forming dunes. It seems likely that the dominant bed sediment size was near the threshold for suspension, and assuming that this was the case could make our final results underestimates, which is the same tendency that our other assumptions have. Making this assumption, we find a global equivalent layer (GEL) of 3-100 m of water to be the most probable cumulative volume that passed through the valley networks. This value is similar to the ∼34 m water GEL currently on the surface and in the near-surface in the form of ice. Note that the amount of water required to carve the valley networks could represent the same water recycled through a surface valley network hydrological system many times in separate or continuous precipitation/runoff/collection/evaporation/precipitation cycles.

On equivalent roughness of mobile bed at high shear stress

Czech Academy of Sciences Publication Activity Database

Matoušek, Václav; Krupička, Jan

2009-01-01

Roč. 57, č. 3 (2009), s. 191-199 ISSN 0042-790X R&D Projects: GA ČR GA103/06/0428 Institutional research plan: CEZ:AV0Z20600510 Keywords : bed shear * experiment * hydraulic transport * sediment transport Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2009

Rock-fluid chemical interactions at reservoir conditions: The influence of brine chemistry and extent of reaction

Science.gov (United States)

Anabaraonye, B. U.; Crawshaw, J.; Trusler, J. P. M.

2016-12-01

Following carbon dioxide injection in deep saline aquifers, CO2 dissolves in the formation brines forming acidic solutions that can subsequently react with host reservoir minerals, altering both porosity and permeability. The direction and rates of these reactions are influenced by several factors including properties that are associated with the brine system. Consequently, understanding and quantifying the impacts of the chemical and physical properties of the reacting fluids on overall reaction kinetics is fundamental to predicting the fate of the injected CO2. In this work, we present a comprehensive experimental study of the kinetics of carbonate-mineral dissolution in different brine systems including sodium chloride, sodium sulphate and sodium bicarbonate of varying ionic strengths. The impacts of the brine chemistry on rock-fluid chemical reactions at different extent of reactions are also investigated. Using a rotating disk technique, we have investigated the chemical interactions between the CO2-saturated brines and carbonate minerals at conditions of pressure (up to 10 MPa) and temperature (up to 373 K) pertinent to carbon storage. The changes in surface textures due to dissolution reaction were studied by means of optical microscopy and vertical scanning interferometry. Experimental results are compared to previously derived models.

Single-phase convection heat transfer characteristics of pebble-bed channels with internal heat generation

International Nuclear Information System (INIS)

Meng Xianke; Sun Zhongning; Xu Guangzhan

2012-01-01

Graphical abstract: The core of the water-cooled pebble bed reactor is the porous channels which stacked with spherical fuel elements. The gaps between the adjacent fuel elements are complex because they are stochastic and often shift. We adopt electromagnetic induction heating method to overall heat the pebble bed. By comparing and analyzing the experimental data, we get the rule of power distribution and the rule of heat transfer coefficient with particle diameter, heat flux density, inlet temperature and working fluid's Re number. Highlights: ► We adopt electromagnetic induction heating method to overall heat the pebble bed to be the internal heat source. ► The ball diameter is smaller, the effect of the heat transfer is better. ► With Re number increasing, heat transfer coefficient is also increasing and eventually tends to stabilize. ► The changing of heat power makes little effect on the heat transfer coefficient of pebble bed channels. - Abstract: The reactor core of a water-cooled pebble bed reactor includes porous channels that are formed by spherical fuel elements. This structure has notably improved heat transfer. Due to the variability and randomness of the interstices in pebble bed channels, heat transfer is complex, and there are few studies regarding this topic. To study the heat transfer characters of pebble bed channels with internal heat sources, oxidized stainless steel spheres with diameters of 3 and 8 mm and carbon steel spheres with 8 mm diameters are used in a stacked pebble bed. Distilled water is used as a refrigerant for the experiments, and the electromagnetic induction heating method is used to heat the pebble bed. By comparing and analyzing the experimental results, we obtain the governing rules for the power distribution and the heat transfer coefficient with respect to particle diameter, heat flux density, inlet temperature and working fluid Re number. From fitting of the experimental data, we obtain the dimensionless average

Effects of mass transfer on MHD flow of casson fluid with chemical reaction and suction

Directory of Open Access Journals (Sweden)

S. A. Shehzad

2013-03-01

Full Text Available Effect of mass transfer in the magnetohydrodynamic flow of a Casson fluid over a porous stretching sheet is addressed in the presence of a chemical reaction. A series solution for the resulting nonlinear flow is computed. The skin friction coefficient and local Sherwood number are analyzed through numerical values for various parameters of interest. The velocity and concentration fields are illustrated for several pertinent flow parameters. We observed that the Casson parameter and Hartman number have similar effects on the velocity in a qualitative sense. We further analyzed that the concentration profile decreases rapidly in comparison to the fluid velocity when we increased the values of the suction parameter.

Nanocalorimetric characterization of microbial activity in deep subsurface oceanic crustal fluids

Directory of Open Access Journals (Sweden)

Alberto eRobador

2016-04-01

Full Text Available Although fluids within the upper oceanic basaltic crust harbor a substantial fraction of the total prokaryotic cells on Earth, the energy needs of this microbial population are unknown. In this study, a nanocalorimeter (sensitivity down to 4.3 x 10-3 mJ h-1 ml-1 was used to measure the enthalpy of microbially catalyzed reactions as a function of temperature in samples from two distinct crustal fluid aquifers. Microorganisms in unamended, warm (63 °C and geochemically altered anoxic fluids taken from 292 meters sub-basement (msb near the Juan de Fuca Ridge produced 267.3 mJ of heat over the course of 97 hours during a step-wise isothermal scan from 35.5 to 85.0 °C. Most of this heat signal likely stems from the germination of thermophilic endospores (6.66 x 104 cells ml-1FLUID and their subsequent metabolic activity at temperatures greater than 50 °C. The average cellular energy consumption (1.79 x 10-7 kJ h-1 cell-1 reveals the high metabolic potential of a dormant community transported by fluids circulating through the ocean crust. By contrast, samples taken from 293 msb from cooler (3.8 °C, relatively unaltered oxic fluids, produced 12.8 mJ of heat over the course of 14 hours as temperature ramped from 34.8 to 43.0 °C. Corresponding cell-specific energy turnover rates (0.18 pW cell-1 were converted to oxygen uptake rates of 24.5 nmol O2 ml-1FLUID d-1, validating previous model predictions of microbial activity in this environment. Given that the investigated fluids are characteristic of expansive areas of the upper oceanic crust, the measured metabolic heat rates can be used to constrain boundaries of habitability and microbial activity in the oceanic crust.

DEPENDENCY OF POLYCHLORINATED BIPHENYL AND POLYCYCLIC AROMATIC HYDROCARBON BIOACCUMULATION IN MYA ARENARIA ON BOTH WATER COLUMN AND SEDIMENT BED CHEMICAL ACTIVITIES

Science.gov (United States)

The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (H...

Numerical Simulation of Dense Gas-Solid Fluidized Beds: A Multiscale Modeling Strategy

NARCIS (Netherlands)

van der Hoef, Martin Anton; van Sint Annaland, M.; Deen, N.G.; Kuipers, J.A.M.

2008-01-01

Gas-solid fluidized beds are widely applied in many chemical processes involving physical and/or chemical transformations, and for this reason they are the subject of intense research in chemical engineering science. Over the years, researchers have developed a large number of numerical models of

Numerical simulation of dense gas-solid fluidized beds : a multiscale modeling strategy

NARCIS (Netherlands)

Hoef, van der M.A.; Sint Annaland, van M.; Deen, N.G.; Kuipers, J.A.M.

2008-01-01

Gas-solid fluidized beds are widely applied in many chemical processes involving physical and/or chemical transformations, and for this reason they are the subject of intense research in chemical engineering science. Over the years, researchers have developed a large number of numerical models of

Maintenance fluid therapy and fluid creep impose more significant fluid, sodium, and chloride burdens than resuscitation fluids in critically ill patients: a retrospective study in a tertiary mixed ICU population.

Science.gov (United States)

Van Regenmortel, Niels; Verbrugghe, Walter; Roelant, Ella; Van den Wyngaert, Tim; Jorens, Philippe G

2018-04-01

Research on intravenous fluid therapy and its side effects, volume, sodium, and chloride overload, has focused almost exclusively on the resuscitation setting. We aimed to quantify all fluid sources in the ICU and assess fluid creep, the hidden and unintentional volume administered as a vehicle for medication or electrolytes. We precisely recorded the volume, sodium, and chloride burdens imposed by every fluid source administered to 14,654 patients during the cumulative 103,098 days they resided in our 45-bed tertiary ICU and simulated the impact of important strategic fluid choices on patients' chloride burdens. In septic patients, we assessed the impact of the different fluid sources on cumulative fluid balance, an established marker of morbidity. Maintenance and replacement fluids accounted for 24.7% of the mean daily total fluid volume, thereby far exceeding resuscitation fluids (6.5%) and were the most important sources of sodium and chloride. Fluid creep represented a striking 32.6% of the mean daily total fluid volume [median 645 mL (IQR 308-1039 mL)]. Chloride levels can be more effectively reduced by adopting a hypotonic maintenance strategy [a daily difference in chloride burden of 30.8 mmol (95% CI 30.5-31.1)] than a balanced resuscitation strategy [daily difference 3.0 mmol (95% CI 2.9-3.1)]. In septic patients, non-resuscitation fluids had a larger absolute impact on cumulative fluid balance than did resuscitation fluids. Inadvertent daily volume, sodium, and chloride loading should be avoided when prescribing maintenance fluids in view of the vast amounts of fluid creep. This is especially important when adopting an isotonic maintenance strategy.

Sympathetic nervous activity decreases during head-down bed rest but not during microgravity

DEFF Research Database (Denmark)

Christensen, Niels J; Heer, Martina; Ivanova, Krassimira

2005-01-01

We tested the hypothesis that sympathoadrenal activity in humans is low during spaceflight and that this effect can be simulated by head-down bed rest (HDBR). Platelet norepinephrine and epinephrine were measured as indexes of long-term changes in sympathoadrenal activity. Ten normal healthy......, and at least 2 wk after return to Earth. Because of the long half-life of platelet norepinephrine, data obtained early after landing would still reflect the microgravity state. Platelet norepinephrine decreased markedly during HDBR (P

The development of nonwoven fabric and agricultural bed soil using kapok fiber for industrial usages

International Nuclear Information System (INIS)

Chung, Byung Yeoup; Kim, Jin Hong; Lee, Seung Sik

2010-01-01

The purpose of this project is the development of nonwoven fabric using natural kapok fiber and synthetic fiber for industrial usages and the development of manufacturing techniques for nursery bed soil using kapok fiber. Research scopes include the development of agricultural bed soil using kapok fiber and nonwoven fabric using kapok fiber. Main results are as follow; the physico-chemical characterization of kapok fiber (water holding capacity, bulk density, water retention curve, viscoelastic measurement, oil adsorption capacity, analysis of essential elements, measurement of anion and cation); the physico-chemical characterization of kapok bed soil; the evidence experiment of kapok bed soil; the optimum content of kapok fiber and synthetic fiber for nonwoven fabric; establishment of the optimum radiation dose for manufacturing kapok nonwoven fabric

Hydrodynamic and thermal modelling of gas-particle flow in fluidized beds

International Nuclear Information System (INIS)

Abdelkawi, O.S; Abdalla, A.M.; Atwan, E.F; Abdelmonem, S.A.; Elshazly, K.M.

2009-01-01

In this study a mathematical model has been developed to simulate two dimensional fluidized bed with uniform fluidization. The model consists of two sub models for hydrodynamic and thermal behavior of fluidized bed on which a FORTRAN program entitled (NEWFLUIDIZED) is devolved. The program is used to predict the volume fraction of gas and particle phases, the velocity of the two phases, the gas pressure and the temperature distribution for two phases. Also the program calculates the heat transfer coefficient. Besides the program predicts the fluidized bed stability and determines the optimum input gas velocity for fluidized bed to achieve the best thermal behavior. The hydrodynamic model is verified by comparing its results with the computational fluid dynamic code MFIX . While the thermal model was tested and compared by the available previous experimental correlations.The model results show good agreement with MFIX results and the thermal model of the present work confirms Zenz and Gunn equations

3D numerical model of the spherical particle saltation in a channel with a rough fixed bed

Czech Academy of Sciences Publication Activity Database

Lukerchenko, Nikolay; Piatsevich, Siarhei; Chára, Zdeněk; Vlasák, Pavel

2009-01-01

Roč. 57, č. 2 (2009), s. 100-112 ISSN 0042-790X R&D Projects: GA ČR GA103/06/1487 Institutional research plan: CEZ:AV0Z20600510 Keywords : 3D Saltation Model * Bed-Load Transport * Particle-Bed Collision * Particle Rotation * Particle Lateral Dispersion Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2009

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Arijit; Koch, Donald L., E-mail: dlk15@cornell.edu [School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853-5201 (United States)

2015-11-15

The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

KAUST Repository

Sarkar, Arijit

2015-11-01

© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

KAUST Repository

Sarkar, Arijit; Koch, Donald L.

2015-01-01

© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

Hydrogeology, chemical and microbial activity measurement through deep permafrost

Energy Technology Data Exchange (ETDEWEB)

Stotler, R.L.; Frape, S.K.; Freifeld, B.M.; Holden, B.; Onstott, T.C.; Ruskeeniemi, T.; Chan, E.

2010-04-01

Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with {delta}{sup 18}O values {approx}5{per_thousand} lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH{sub 4} was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH{sub 4} is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination.

Fluid-chemical evidence for one billion years of fluid flow through Mesoproterozoic deep-water carbonate mounds (Nanisivik zinc district, Nunavut)

Science.gov (United States)

Hahn, K. E.; Turner, E. C.; Kontak, D. J.; Fayek, M.

2018-02-01

Ancient carbonate rocks commonly contain numerous post-depositional phases (carbonate minerals; quartz) recording successive diagenetic events that can be deciphered and tied to known or inferred geological events using a multi-pronged in situ analytical protocol. The framework voids of large, deep-water microbial carbonate seep-mounds in Arctic Canada (Mesoproterozoic Ikpiarjuk Formation) contain multiple generations of synsedimentary and late cement. An in situ analytical study of the post-seafloor cements used optical and cathodoluminescence petrography, SEM-EDS analysis, fluid inclusion (FI) microthermometry and evaporate mound analysis, LA-ICP-MS analysis, and SIMS δ18O to decipher the mounds' long-term diagenetic history. The six void-filling late cements include, in paragenetic order: inclusion-rich euhedral dolomite (ED), finely crystalline clear dolomite (FCD), hematite-bearing dolomite (HD), coarsely crystalline clear dolomite (CCD), quartz (Q), replacive calcite (RC) and late calcite (LC). Based on the combined analytical results, the following fluid-flow history is defined: (1) ED precipitation by autocementation during shallow burial (fluid 1; Mesoproterozoic); (2) progressive mixing of Ca-rich hydrothermal fluid with the connate fluid, resulting in precipitation of FCD followed by HD (fluid 2; also Mesoproterozoic); (3) precipitation of hydrothermal dolomite (CCD) from high-Ca and K-rich fluids (fluid 3; possibly Mesoproterozoic, but timing unclear); (4) hydrothermal Q precipitation (fluid 4; timing unclear), and (5) RC and LC precipitation from a meteoric-derived water (fluid 5) in or since the Mesozoic. Fluids associated with FCD, HD, and CCD may have been mobilised during deposition of the upper Bylot Supergroup; this time interval was the most tectonically active episode in the region's Mesoproterozoic to Recent history. The entire history of intermittent fluid migration and cement precipitation recorded in seemingly unimportant void

Prevention of Bed Agglomeration Problems in a Fluidized Bed Boiler by Finding the Trigging Value of Sewage Sludge Dosage Added to Combustion of Biofuels

Energy Technology Data Exchange (ETDEWEB)

Andersson, Kajsa; Gervind, Pernilla

2009-07-01

Agglomeration of bed sand is a common problem during combustion of biofuels with high ash content in fluidized bed boilers. Former studies have shown that co-combustion of biofuels with sewage sludge increases the agglomeration temperature. Sewage sludge has a low heating value and high ash content. It would therefore be better to use sludge as an additive to the combustion than as a co-combusted biofuel. In this study the trigging value of sludge addition to the combustion of some biofuel was investigated. The effect of adding sludge with different precipitation chemicals, iron sulphate and aluminium sulphate, was investigated. The biofuels used for the experiments were bark, refused derived fuel (RDF) and a mixture of wood and straw, 75/25 % on energy basis. All experiments were carried out in a laboratory scale fluidized bed reactor. Analyses of chemical composition of bed sand and SEM/EDX analyses were performed after the combustion. Eventually agglomeration tests were performed in order to find the agglomeration temperature of the samples. Some of the samples sintered during the combustion and were not tested for the agglomeration temperature. SEM/EDX showed that all samples of bed sand contained sand particles with more or less coatings. In some cases the coatings seemed to consist of one dense inner layer and one more porous outer layer. From SEM/EDX and chemical composition analyses it was found that the total amount of phosphorous in the bed sand samples was increased with an increased addition of sludge in all experiments. The concentration of phosphorous was especially higher in the outer layers/coatings. It was also found that elements from the sludge seem to get caught by a sticky layer at the bed sand surface and form a non-sticky or less sticky layer that prevents agglomeration. The total amount of aluminium was increased with an increased addition of sludge for the wood/straw samples, while it increased with an increased amount of combusted fuel for

CFD Modeling of Flow and Ion Exchange Kinetics in a Rotating Bed Reactor System

DEFF Research Database (Denmark)

Larsson, Hilde Kristina; Schjøtt Andersen, Patrick Alexander; Byström, Emil

2017-01-01

A rotating bed reactor (RBR) has been modeled using computational fluid dynamics (CFD). The flow pattern in the RBR was investigated and the flow through the porous material in it was quantified. A simplified geometry representing the more complex RBR geometry was introduced and the simplified...... model was able to reproduce the main characteristics of the flow. Alternating reactor shapes were investigated, and it was concluded that the use of baffles has a very large impact on the flows through the porous material. The simulations suggested, therefore, that even faster reaction rates could...... be achieved by making the baffles deeper. Two-phase simulations were performed, which managed to reproduce the deflection of the gas–liquid interface in an unbaffled system. A chemical reaction was implemented in the model, describing the ion-exchange phenomena in the porous material using four different...

Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

Science.gov (United States)

Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

2017-07-01

This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium ( q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) were determined and the positive value of (Δ H) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

PIT-tagged particle study of bed mobility in a Maine salmon river impacted by logging activities

Science.gov (United States)

Thompson, D. M.; Fixler, S. A.; Roberts, K. E.; McKenna, M.; Marshall, A. E.; Koenig, S.

2017-12-01

Presenting an interim report on a study on the Narraguagus River in Maine, which utilizes laser total stations cross-sectional surveys and tracking of passive integrated transponder (PIT) tags embedded in glass spheres to document changes in channel-bed characteristics associated with large wood (LW) additions and natural spawning activities. In 2016, work was initiated to monitor changes in bed elevation and sediment mobility with the addition of LW to the Narraguagus River as part of a restoration effort. Ten cross-sections, spaced 5-m apart, were established and surveyed with a laser total station in each of three different study reaches. The study sites include a control reach, a section with anticipated spawning activities and a site with ongoing LW placement. A grid of 200 glass spheres embedded with PIT tags, with twenty alternating 25-mm and 40-mm size particles equally spaced along each of the ten transects, were placed to serve as point sensors to detect sediment mobilization within each reach. In 2017, the site was revisited to determine if differences in PIT-tagged tracer particle mobilization reflect locations were LW was added and places where Atlantic salmon (Salmo salar) and sea lamprey (Petromyzon marinus) construct spawning redds. The positions of PIT-tagged tracer particles was recorded, but particles were not disturbed or uncovered to permit study of potential reworking of buried tracer particles the following year. Full tracer particle recovery will be determined in 2018 to determine if depths of tracer burial and changes in bed elevation vary among places near redds, LW and main channel locations. The data will be used to determine if salmon redds are preferentially located in either places with greater evidence of sediment reworking or alternatively in stable areas? The study will help determine the degree of bed disruption associated with spawning activities and whether LW placement encourages similar sediment mobilization processes.

Sodium/water pool-deposit bed model of the CONACS code

International Nuclear Information System (INIS)

Peak, R.D.

1983-01-01

A new Pool-Bed model of the CONACS (Containment Analysis Code System) code represents a major advance over the pool models of other containment analysis code (NABE code of France, CEDAN code of Japan and CACECO and CONTAIN codes of the United States). This new model advances pool-bed modeling because of the number of significant materials and processes which are included with appropriate rigor. This CONACS pool-bed model maintains material balances for eight chemical species (C, H 2 O, Na, NaH, Na 2 O, Na 2 O 2 , Na 2 CO 3 and NaOH) that collect in the stationary liquid pool on the floor and in the desposit bed on the elevated shelf of the standard CONACS analysis cell

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

Energy Technology Data Exchange (ETDEWEB)

Soria, J. [Instituto Multidisciplinario de Investigación y Desarrollo de la Patagonia Norte (IDEPA, CONICET-UNCo) y Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquén (Argentina); Laboratoire Procédés, Matériaux et Energie Solaire (CNRS-PROMES), 7 Rue du Four Solaire, Odeillo, 66120 Font-Romeu (France); Gauthier, D., E-mail: Daniel.Gauthier@promes.cnrs.fr [Laboratoire Procédés, Matériaux et Energie Solaire (CNRS-PROMES), 7 Rue du Four Solaire, Odeillo, 66120 Font-Romeu (France); Falcoz, Q.; Flamant, G. [Laboratoire Procédés, Matériaux et Energie Solaire (CNRS-PROMES), 7 Rue du Four Solaire, Odeillo, 66120 Font-Romeu (France); Mazza, G. [Instituto Multidisciplinario de Investigación y Desarrollo de la Patagonia Norte (IDEPA, CONICET-UNCo) y Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300 Neuquén (Argentina)

2013-03-15

Highlights: ► A 2-D local CFD model for simulating the Cd vaporization process is presented. ► It includes a kinetic expression of Cd vaporization into the incineration process. ► Pyrolysis, volatiles’ combustion and residual carbon combustion are also taken into account. ► It fits very well the experimental results obtained on a lab-scale fluidized bed reported in literature. ► It also compares favorably with a model developed previously by the group. -- Abstract: 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.

Modeling bubble heat transfer in gas-solid fluidized beds using DEM

NARCIS (Netherlands)

Patil, A.V.; Peters, E.A.J.F.; Kolkman, T.; Kuipers, J.A.M.

2014-01-01

Discrete element method (DEM) simulations of a pseudo 2-D fluidized bed at non-isothermal conditions are presented. First implementation details are discussed. This is followed by a validation study where heating of a packed column by a flow of heated fluid is considered. Next hot gas injected into

Transient thermal response of a packed bed for energy storage unit utilizing phase change material: experimental and numerical study

International Nuclear Information System (INIS)

Bemansour, A.

2006-01-01

The present work concerns the numerical and experimental study of the transient response of a packed bed latent heat thermal energy storage system. Experiments were carried out to measures the transient temperature distributions inside a cylindrical bed, which is randomly packed with spheres having uniform sizes and encapsulated the paraffin wax as a phase change material (PCM), with air as a working fluid. A two-dimensional separate phases formulation is used to develop a numerical analysis of the transient response of the bed, considering the influence of both axial and radial thermal dispersion. The fluid energy equation was transformed by finite difference approximation and solved by alternating direction implicit scheme, while the PCM energy equation was solved using fully explicit scheme. This analysis can be applied for both charging and recovery modes and a broad range of Reynolds numbers. Measurements of both fluid and PCM temperature were conducted at different axial and radial positions and at different operating parameters. Experimental measurements of temperature distribution compare favorably with the numerical results over a broad range of Reynolds numbers.(Author)

Continuous adsorption and biotransformation of micropollutants by granular activated carbon-bound laccase in a packed-bed enzyme reactor.

Science.gov (United States)

Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

2016-06-01

Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

Parallel-Processing Test Bed For Simulation Software

Science.gov (United States)

Blech, Richard; Cole, Gary; Townsend, Scott

1996-01-01

Second-generation Hypercluster computing system is multiprocessor test bed for research on parallel algorithms for simulation in fluid dynamics, electromagnetics, chemistry, and other fields with large computational requirements but relatively low input/output requirements. Built from standard, off-shelf hardware readily upgraded as improved technology becomes available. System used for experiments with such parallel-processing concepts as message-passing algorithms, debugging software tools, and computational steering. First-generation Hypercluster system described in "Hypercluster Parallel Processor" (LEW-15283).

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

Science.gov (United States)

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.

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

Science.gov (United States)

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. Copyright © 2013 Elsevier B.V. All rights reserved.

Mesoscopic dispersion of colloidal agglomerate in a complex fluid modelled by a hybrid fluid-particle model.

Science.gov (United States)

Dzwinel, Witold; Yuen, David A

2002-03-15

The dispersion of the agglomerating fluid process involving colloids has been investigated at the mesoscale level by a discrete particle approach--the hybrid fluid-particle model (FPM). Dynamical processes occurring in the granulation of colloidal agglomerate in solvents are severely influenced by coupling between the dispersed microstructures and the global flow. On the mesoscale this coupling is further exacerbated by thermal fluctuations, particle-particle interactions between colloidal beds, and hydrodynamic interactions between colloidal beds and the solvent. Using the method of FPM, we have tackled the problem of dispersion of a colloidal slab being accelerated in a long box filled with a fluid. Our results show that the average size of the agglomerated fragments decreases with increasing shearing rate gamma, according to the power law A x gamma(k), where k is around 2. For larger values of gamma, the mean size of the agglomerate S(avg) increases slowly with gamma from the collisions between the aggregates and the longitudinal stretching induced by the flow. The proportionality constant A increases exponentially with the scaling factor of the attractive forces acting between the colloidal particles. The value of A shows a rather weak dependence on the solvent viscosity. But A increases proportionally with the scaling factor of the colloid-solvent dissipative interactions. Similar type of dependence can be found for the mixing induced by Rayleigh-Taylor instabilities involving the colloidal agglomerate and the solvent. Three types of fragmentation structures can be identified, which are called rupture, erosion, and shatter. They generate very complex structures with multiresolution character. The aggregation of colloidal beds is formed by the collisions between aggregates, which are influenced by the flow or by the cohesive forces for small dispersion energies. These results may be applied to enhance our understanding concerning the nonlinear complex

Process Optimization for Ethyl Ester Production in Fixed Bed Reactor Using Calcium Oxide Impregnated Palm Shell Activated Carbon (CaO/PSAC

Directory of Open Access Journals (Sweden)

A Buasri

2012-11-01

Full Text Available : The continuous production of ethyl ester was studied by using a steady-state fixed bed reactor (FBR. Transesterification of palm stearin (PS and waste cooking palm oil (WCPO with ethanol in the presence of calcium oxide impregnated palm shell activated carbon (CaO/PSAC solid catalyst was investigated. This work was determined the optimum conditions for the production of ethyl ester from PS and WCPO in order to obtain fatty acid ethyl ester (FAEE with the highest yield. The effects of reaction variables such as residence time, ethanol/oil molar ratio, reaction temperature, catalyst bed height and reusability of catalyst in a reactor system on the yield of biodiesel were considered. The optimum conditions were the residence time 2-3 h, ethanol/oil molar ratio 16-20, reaction temperature at 800C, and catalyst bed height 300 mm which yielded 89.46% and 83.32% of the PS and WCPO conversion, respectively. CaO/PSAC could be used repeatedly for 4 times without any activation treatment and no obvious activity loss was observed. It has potential for industrial application in the transesterification of triglyceride (TG. The fuel properties of biodiesel were determined. Keywords: biodiesel, calcium oxide, ethyl ester, fixed bed reactor, palm shell activated carbon

Nuclear activated cw chemical laser

International Nuclear Information System (INIS)

Roberts, T.G.

1982-01-01

A cw chemical laser which uses processed radioactive waste to produce active atoms from a chemically inactive gas before being mixed with another molecule such as hydrogen or deuterium is disclosed. This laser uses no toxic or corrosive fuels and does not require any electrical or other type of auxiliary power supply. The energy released by the radioactive material is used to produce the active atoms such as fluorine. This is accomplished by using the radiation products from processed radioactive waste to dissociate the inert gas in the plenum of the laser. The radioactive material is held in the passageway walls of a device similar to a heat exchanger. The exchanger device may be located in the gas generator section of a chemical laser. The inactive gas is passed through the exchanger device and while passing through it the radiation from the radioactive material dissociates the gas, producing a concentration of free active atoms. This active atom generator then feeds the nozzle bank or mixing section of a laser to produce a lasing action

Fluid dynamics of air in a packed bed: velocity profiles and the continuum model assumption

Directory of Open Access Journals (Sweden)

NEGRINI A. L.

1999-01-01

Full Text Available Air flow through packed beds was analyzed experimentally under conditions ranging from those that reinforce the effect of the wall on the void fraction to those that minimize it. The packing was spherical particles, with a tube-to-particle diameter ratio (D/dp between 3 and 60. Air flow rates were maintained between 1.3 and 4.44 m3/min, and gas velocity was measured with a Pitot tube positioned above the bed exit. Measurements were made at various radial and angular coordinate values, allowing the distribution of air flow across the bed to be described in detail. Comparison of the experimentally observed radial profiles with those derived from published equations revealed that at high D/dp ratios the measured and calculated velocity profiles behaved similarly. At low ratios, oscillations in the velocity profiles agreed with those in the voidage profiles, signifying that treating the porous medium as a continuum medium is questionable in these cases.

Granular controls on the dispersion of bed load tracers

Science.gov (United States)

Jerolmack, D. J.; Martin, R. L.; Phillips, C. B.

2014-12-01

Coarse particles are transported in a river as bed load, i.e., they move in frequent contact with and are supported by the granular bed. This movement is typically intermittent and may be described by a series of steps are rests, the distributions of which determine particle dispersion. Laboratory and field studies of bed load tracer dispersion have reported sub- and super-diffusive behavior, both of which have been successfully reproduced with stochastic transport models. Although researchers have invoked heavy-tailed step lengths as the cause of anomalous dispersion, most observations report thin-tailed distributions. Little attention has been paid to rest periods, and stochastic transport models have not been connected to the underlying mechanics of particle motion. Based on theoretical and experimental evidence, we argue that step lengths are thin-tailed and do not control the longterm dispersion of bed load tracers; they are determined by momentum balance between the fluid and solid. Using laboratory experiments with both marbles and natural sediments, we demonstrate that the rest time distribution is power law, and argue that this distribution controls asymptotic dispersion. Observed rest times far exceed any hydrodynamic timescale. Experiments reveal that rest times of deposited particles are governed by fluctuations in river bed elevation; in particular, the return time for the bed to scour to the base of a deposited particle. Stochastic fluctuations in bed elevation are describable by an Ornstein-Uhlenbeck (mean-reverting random walk) model that contains two parameters, which we show are directly related to the granular shear rate and range of bed elevation fluctuations, respectively. Combining these results with the theory of asymmetric random walks (particles only move downstream), we predict superdiffusive behavior that is in quantitative agreement with our observations of tracer dispersion in a natural river.

Numerical investigation of fluid mud motion using a three-dimensional hydrodynamic and two-dimensional fluid mud coupling model

Science.gov (United States)

Yang, Xiaochen; Zhang, Qinghe; Hao, Linnan

2015-03-01

A water-fluid mud coupling model is developed based on the unstructured grid finite volume coastal ocean model (FVCOM) to investigate the fluid mud motion. The hydrodynamics and sediment transport of the overlying water column are solved using the original three-dimensional ocean model. A horizontal two-dimensional fluid mud model is integrated into the FVCOM model to simulate the underlying fluid mud flow. The fluid mud interacts with the water column through the sediment flux, current, and shear stress. The friction factor between the fluid mud and the bed, which is traditionally determined empirically, is derived with the assumption that the vertical distribution of shear stress below the yield surface of fluid mud is identical to that of uniform laminar flow of Newtonian fluid in the open channel. The model is validated by experimental data and reasonable agreement is found. Compared with numerical cases with fixed friction factors, the results simulated with the derived friction factor exhibit the best agreement with the experiment, which demonstrates the necessity of the derivation of the friction factor.

Flow of power-law fluids in fixed beds of cylinders or spheres

KAUST Repository

Singh, John P.; Padhy, Sourav; Shaqfeh, Eric S. G.; Koch, Donald L.

2012-01-01

is influenced by the Newtonian fluid stress and a body force representing the linear drag on the surrounding particles. We consider a similar analysis for a power-law fluid where the stress τ is related to the rate of strain e by τ = 2m en-1e, where m and n

Magnetohydraulic flow through a packed bed of electrically conducting spheres

International Nuclear Information System (INIS)

Sanders, T.L.

1985-01-01

The flow of an electrically conducting fluid through a packed bed of electrically conducting spheres in the presence of a strong magnetic field constitutes a very complex flow situation due to the constant turning of the fluid in and out of magnetic field lines. The interaction of the orthogonal components of the velocity and magnetic field will induce electric fields that are orthogonal to both and the electric fields in turn can cause currents that interact with the magnetic field to generate forces against the direction of flow. The strengths of these generated forces depend primarily upon the closure paths taken by the induced currents which, in turn, depend upon the relative ratio of the electrical resistance of the solid spheres to that of the fluid. Both experimental and analytical analyses of the slow flow of a eutectic mixture of sodium and potassium (NaK) through packed cylinders containing stainless steel spheres in the presence of a strong transverse magnetic field were completed. A theory of magnetohydraulic flow is developed by analogy with the development of hydraulic radius theories of flow through porous media. An exact regional analysis is successfully applied to an infinite bed of electrically conducting spheres with a conducting or non-conducting constraining wall on one side. The equations derived are solved for many different combinations of flowrate, magnetic field strength, porosity, and electrical resistance ratio

A comparative study of charcoal gasification in two types of spouted bed reactors

International Nuclear Information System (INIS)

Abdul Salam, P.; Bhattacharya, S.C.

2006-01-01

Gasification is considered to be a favourable method for converting a solid fuel into a more versatile gaseous fuel. Performance of a gasifier depends on the design of the gasifier, type of fuel used and air flow rate, etc. The applications of spouted bed for a variety of processes such as drying, coating, pyrolysis, gasification and combustion have been reported. Gasification of solid fuels in a spouted bed, which has certain potential advantages over other fluid bed configurations, appears to be an under-exploited technique so far. Central jet distributors are the most commonly used in the experimental studies that has been reported in the literature. Circular slit distributor is a new concept. This paper presents results of a comparative experimental study on air gasification of charcoal in central jet and circular slit inert sand spouted beds. The experiments were carried for an equivalence ratio of 0.25. The effect of spouting velocity and type of the distributor on the gasification performance were discussed. The steady state dense bed temperature varied between 979 and 1183 deg C for central jet spouted bed and between 964 and 1235 deg C for circular slit spouted bed. At higher spouting velocities, the gasification efficiency of the circular slit spouted bed was slightly more compared with that of central jet spouted bed

On the fluid mechanics of fires

Energy Technology Data Exchange (ETDEWEB)

TIESZEN,SHELDON R.

2000-02-29

Fluid mechanics research related to fire is reviewed with focus on canonical flows, multiphysics coupling aspects, experimental and numerical techniques. Fire is a low-speed, chemically-reacting, flow in which buoyancy plans an important role. Fire research has focused on two canonical flows, the reacting boundary-layer and the reacting free plume. There is rich, multi-lateral, bi-directional, coupling among fluid mechanics and scalar transport, combustion, and radiation. There is only a limited experimental fluid-mechanics database for fire due to measurement difficulties in the harsh environment, and the focus within the fire community on thermal/chemical consequences. Increasingly, computational fluid dynamics techniques are being used to provide engineering guidance on thermal/chemical consequences and to study fire phenomenology.

Submicron and Nanoparticulate Matter Removal by HEPA-Rated Media Filters and Packed Beds of Granular Materials

Science.gov (United States)

Perry, J. L.; Agui, J. H.; Vijayakimar, R

2016-01-01

Contaminants generated aboard crewed spacecraft by diverse sources consist of both gaseous chemical contaminants and particulate matter. Both HEPA media filters and packed beds of granular material, such as activated carbon, which are both commonly employed for cabin atmosphere purification purposes have efficacy for removing nanoparticulate contaminants from the cabin atmosphere. The phenomena associated with particulate matter removal by HEPA media filters and packed beds of granular material are reviewed relative to their efficacy for removing fine (less than 2.5 micrometers) and ultrafine (less than 0.01 micrometers) sized particulate matter. Considerations are discussed for using these methods in an appropriate configuration to provide the most effective performance for a broad range of particle sizes including nanoparticulates.

Comparison of PIV measurements and a discrete particle model in a rectangular 3D spout-fluid bed

NARCIS (Netherlands)

Link, J.M.; Deen, N.G.; Kuipers, J.A.M.

2004-01-01

Particle image velocimetry and a 3D hard sphere discrete particle model were applied to determine particle velocity profiles in the plane around a spout in a spoutfluid bed for various initial bed heights, spout and background fluidization velocities. Comparison between experimental and numerical

CFD-DEM Onset of Motion Analysis for Application to Bed Scour Risk Assessment

Energy Technology Data Exchange (ETDEWEB)

Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States)

2017-03-01

This CFD study with DEM was done as a part of the Federal Highway Administration’s (FHWA’s) effort to improve scour design procedures. The Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) model, available in CD-Adapco’s StarCCM+ software, was used to simulate multiphase systems, mainly those which combine fluids and solids. In this method the motion of discrete solids is accounted for by DEM, which applies Newton's laws of motion to every particle. The flow of the fluid is determined by the local averaged Navier–Stokes equations that can be solved using the traditional CFD approach. The interactions between the fluid phase and solids phase are modeled by use of Newton's third law. The inter-particle contact forces are included in the equations of motion. Soft-particle formulation is used, which allows particles to overlap. In this study DEM was used to model separate sediment grains and spherical particles laying on the bed with the aim to analyze their movement due to flow conditions. Critical shear stress causing the incipient movement of the sediment was established and compared to the available experimental data. An example of scour around a cylindrical pier is considered. Various depths of the scoured bed and flow conditions were taken into account to gain a better understanding of the erosion forces existing around bridge foundations. The decay of these forces with increasing scour depth was quantified with a ‘decay function’, which shows that particles become increasingly less likely to be set in motion by flow forces as a scour hole increases in depth. Computational and experimental examples of the scoured bed around a cylindrical pier are presented.

Hydrogeology, chemical and microbial activity measurement through deep permafrost.

Science.gov (United States)

Stotler, Randy L; Frape, Shaun K; Freifeld, Barry M; Holden, Brian; Onstott, Tullis C; Ruskeeniemi, Timo; Chan, Eric

2011-01-01

Little is known about hydrogeochemical conditions beneath thick permafrost, particularly in fractured crystalline rock, due to difficulty in accessing this environment. The purpose of this investigation was to develop methods to obtain physical, chemical, and microbial information about the subpermafrost environment from a surface-drilled borehole. Using a U-tube, gas and water samples were collected, along with temperature, pressure, and hydraulic conductivity measurements, 420 m below ground surface, within a 535 m long, angled borehole at High Lake, Nunavut, Canada, in an area with 460-m-thick permafrost. Piezometric head was well above the base of the permafrost, near land surface. Initial water samples were contaminated with drill fluid, with later samples <40% drill fluid. The salinity of the non-drill fluid component was <20,000 mg/L, had a Ca/Na ratio above 1, with δ(18) O values ∼5‰ lower than the local surface water. The fluid isotopic composition was affected by the permafrost-formation process. Nonbacteriogenic CH(4) was present and the sample location was within methane hydrate stability field. Sampling lines froze before uncontaminated samples from the subpermafrost environment could be obtained, yet the available time to obtain water samples was extended compared to previous studies. Temperature measurements collected from a distributed temperature sensor indicated that this issue can be overcome easily in the future. The lack of methanogenic CH(4) is consistent with the high sulfate concentrations observed in cores. The combined surface-drilled borehole/U-tube approach can provide a large amount of physical, chemical, and microbial data from the subpermafrost environment with few, controllable, sources of contamination. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

Bubble Swarm Rise Velocity in Fluidized Beds.

Czech Academy of Sciences Publication Activity Database

Punčochář, Miroslav; Růžička, Marek; Šimčík, Miroslav

2016-01-01

Roč. 152, OCT 2 (2016), s. 84-94 ISSN 0009-2509 R&D Projects: GA ČR(CZ) GA15-05534S Institutional support: RVO:67985858 Keywords : bubbling fluidized bed * gas-solid * bubble swarm velocity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.895, year: 2016

Lytic activities in coelomic fluid of Eisenia foetida and Lumbricus terrestris.

Science.gov (United States)

Tucková, L; Rejnek, J; Síma, P; Ondrejová, R

1986-01-01

Coelomic fluids of the two earthworm species E.foetida (E.F.) and L.terrestris (L.T.) have not only the ability to lyse various vertebrate erythrocytes but also to digest vertebrate serum proteins. Both activities are carried by different molecules since hemolysis but not proteolysis was inhibited by simple sugars. In contrary, proteolysis was blocked by PMSF which did not influence hemolysis. Coelomic fluids of E.F. digest effectively vertebrate serum proteins (PIgG, HSA) but not the proteins of L.T. coelomic fluids. The proteolytic activity was detected in approximately 40 000 mol. wt. fraction. After digestion proteolytic fragments were analyzed by immunoelectrophoresis, SDS-PAGE and TCA precipitation. Two of the fragments reacting with PIgG antisera remained intact even after 120 h digestion.

Two-fluid spray atomisation and pneumatic nozzles for fluid bed coating/agglomeration purposes: A review

DEFF Research Database (Denmark)

Hede, Peter Dybdahl; Bach, Poul; Jensen, Anker Degn

2008-01-01

understood. This paper provides a systematic and up-to-date review of two-fluid nozzle designs and principles together with a presentation of nozzle fundamentals introducing basic nozzle theory and thermodynamics. Correlations for the prediction of mean droplet diameters are reviewed, compared...

Chemical Technology Division annual technical report, 1988

International Nuclear Information System (INIS)

1989-05-01

Highlights of the Chemical Technology (CMT) Divisions's activities during 1988 are presented. In this period, CMT conducted research and development in the following areas: (1) high-performance batteries (mainly lithium-alloy/metal sulfide, sodium/metal chloride, and sodium/sulfur); (2) aqueous batteries (lead-acid, nickel/iron, etc.); (3) advanced fuel cells with molten carbonate or solid oxide electrolytes; (4) coal utilization, including the heat and seed recovery technology for coal-fired magnetohydrodynamics plants and the technology for fluidized-bed combustion; (5) methods for recovery of energy from municipal waste and techniques for treatment of hazardous chemical water; (6) nuclear technology related to a process for separating and recovering transuranic elements from nuclear waste and for producing /sup 99/Mo from low-enriched uranium targets, the recovery processes for discharged fuel and the uranium blanket in a sodium-cooled fast reactor, and waste management; and (7) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also has a program in basic chemistry research in the areas of fluid catalysis for converting small molecules to desired products; materials chemistry for superconducting oxides and associated and ordered solutions at high temperatures; interfacial processes of importance to corrosion science, high-temperature superconductivity, and catalysis; and the geochemical processes responsible for trace-element migration within the earth's crust. The Division continued to be the major user of the technical support provided by the Analytical Chemistry Laboratory at ANL. 53 figs., 16 tabs

Low-pass filtered continuum streambed and bedload sediment mass balance laws for an alluvial, gravel-bed stream

Science.gov (United States)

DeTemple, B.; Wilcock, P.

2011-12-01

In an alluvial, gravel-bed stream governed by a plane-bed bedload transport regime, the physicochemical properties, size distribution, and granular architecture of the sediment grains that constitute the streambed surface influence many hydrodynamic, geomorphic, chemical, and ecological processes. Consequently, the abilities to accurately characterize the morphology and model the morphodynamics of the streambed surface and its interaction with the bedload above and subsurface below are necessary for a more complete understanding of how sediment, flow, organisms, and biogeochemistry interact. We report on our progress in the bottom-up development of low-pass filtered continuum streambed and bedload sediment mass balance laws for an alluvial, gravel-bed stream. These balance laws are assembled in a four stage process. First, the stream sediment-water system is conceptually abstracted as a nested, multi-phase, multi-species, structured continuum. Second, the granular surface of an aggregate of sediment grains is mathematically defined. Third, an integral approach to mass balance, founded in the continuum theory of multiphase flow, is used to formulate primordial, differential, instantaneous, local, continuum, mass balance laws applicable at any material point within a gravel-bed stream. Fourth, area averaging and time-after-area averaging, employing planform, low-pass filtering expressed as correlation or convolution integrals and based on the spatial and temporal filtering techniques found in the fields of multiphase flow, porous media flow, and large eddy simulation of turbulent fluid flow, are applied to smooth the primordial equations while maximizing stratigraphic resolution and preserving the definitions of relevant morphodynamic surfaces. Our approach unifies, corrects, contextualizes, and generalizes prior efforts at developing stream sediment continuity equations, including the top-down derivations of the surface layer (or "active layer") approach of Hirano

Mixed convection in fluid superposed porous layers

CERN Document Server

Dixon, John M

2017-01-01

This Brief describes and analyzes flow and heat transport over a liquid-saturated porous bed. The porous bed is saturated by a liquid layer and heating takes place from a section of the bottom. The effect on flow patterns of heating from the bottom is shown by calculation, and when the heating is sufficiently strong, the flow is affected through the porous and upper liquid layers. Measurements of the heat transfer rate from the heated section confirm calculations. General heat transfer laws are developed for varying porous bed depths for applications to process industry needs, environmental sciences, and materials processing. Addressing a topic of considerable interest to the research community, the brief features an up-to-date literature review of mixed convection energy transport in fluid superposed porous layers.

Bacillus cereus in free-stall bedding.

Science.gov (United States)

Magnusson, M; Svensson, B; Kolstrup, C; Christiansson, A

2007-12-01

To increase the understanding of how different factors affect the bacterial growth in deep sawdust beds for dairy cattle, the microbiological status of Bacillus cereus and coliforms in deep sawdust-bedded free stalls was investigated over two 14-d periods on one farm. High counts of B. cereus and coliforms were found in the entire beds. On average, 4.1 log(10) B. cereus spores, 5.5 log(10) B. cereus, and 6.7 log(10) coliforms per gram of bedding could be found in the upper layers of the sawdust likely to be in contact with the cows' udders. The highest counts of B. cereus spores, B. cereus, and coliforms were found in the bedding before fresh bedding was added, and the lowest immediately afterwards. Different factors of importance for the growth of B. cereus in the bedding material were explored in laboratory tests. These were found to be the type of bedding, pH, and the type and availability of nutrients. Alternative bedding material such as peat and mixtures of peat and sawdust inhibited the bacterial growth of B. cereus. The extent of growth of B. cereus in the sawdust was increased in a dose-dependent manner by the availability of feces. Urine added to different bedding material raised the pH and also led to bacterial growth of B. cereus in the peat. In sawdust, a dry matter content greater than 70% was needed to lower the water activity to 0.95, which is needed to inhibit the growth of B. cereus. In an attempt to reduce the bacterial growth of B. cereus and coliforms in deep sawdust beds on the farm, the effect of giving bedding daily or a full replacement of the beds was studied. The spore count of B. cereus in the back part of the free stalls before fresh bedding was added was 0.9 log units lower in stalls given daily bedding than in stalls given bedding twice weekly. No effect on coliform counts was found. Replacement of the entire sawdust bedding had an effect for a short period, but by 1 to 2 mo after replacement, the counts of B. cereus spores in the

Chemical Technology Division annual technical report, 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-06-01

Highlights of the Chemical Technology (CMT) Division`s activities during 1994 are presented. In this period, CMT conducted research and development in the following areas: (1) electrochemical technology, including advanced batteries and fuel cells; (2) technology for fluidized-bed combustion; (3) methods for treatment of hazardous waste and mixed hazardous/radioactive waste; (4) the reaction of nuclear waste glass and spent fuel under conditions expected for an unsaturated repository; (5) processes for separating and recovering transuranic elements from waste streams, concentrating radioactive waste streams with advanced evaporator technology, and producing {sup 99}Mo from low-enriched uranium for medical applications; (6) electrometallurgical treatment of the many different types of spent nuclear fuel in storage at Department of Energy sites; and (8) physical chemistry of selected materials in environments simulating those of fission and fusion energy systems. The Division also conducts basic research in catalytic chemistry associated with molecular energy resources and novel ceramic precursors; materials chemistry of superconducting oxides, electrified metal/solution interfaces, molecular sieve structures, and impurities in scrap copper and steel; and the geochemical processes involved in mineral/fluid interfaces and water-rock interactions occurring in active hydrothermal systems. In addition, the Analytical Chemistry Laboratory in CMT provides a broad range of analytical chemistry support services to the technical programs at Argonne National Laboratory (ANL).

Bed Utilisation in an Irish Regional Paediatric Unit – A Cross-Sectional Study Using the Paediatric Appropriateness Evaluation Protocol (PAEP

Directory of Open Access Journals (Sweden)

Coilín ÓhAiseadha

2016-11-01

Full Text Available Background Increasing demand for limited healthcare resources raises questions about appropriate use of inpatient beds. In the first paediatric bed utilisation study at a regional university centre in Ireland, we conducted a cross-sectional study to audit the utilisation of inpatient beds at the Regional Paediatric Unit (RPU in University Hospital Limerick (UHL, Limerick, Ireland and also examined hospital activity data, to make recommendations for optimal use of inpatient resources. Methods We used a questionnaire based on the paediatric appropriateness evaluation protocol (PAEP, modified and validated for use in the United Kingdom, to prospectively gather data regarding reasons for admission and for ongoing care after 2 days, from case records for all inpatients during 11 days in February (winter and 7 days in May–June (summer. We conducted bivariate and multivariate analysis to explore associations between failure to meet PAEP criteria and patient attributes including age, gender, admission outside of office hours, arrival by ambulance, and private health insurance. Inpatient bed occupancy and day ward activity were also scrutinised. Results Mean bed occupancy was 84.1%. In all, 12/355 (3.4%, 95% CI: 1.5%–5.3% of children failed to meet PAEP admission criteria, and 27/189 (14.3%, 95% CI: 9.3%–19.3% who were still inpatients after 2 days failed to meet criteria for ongoing care. 35/355 (9.9%, 95% CI: 6.8%–13.0% of admissions fulfilled only the PAEP criterion for intravenous medications or fluid replacement. A logistic regression model constructed by forward selection identified a significant association between failure to meet PAEP criteria for ongoing care 2 days after admission and admission during office hours (08.00–17.59 (P = .020, and a marginally significant association between this outcome and arrival by ambulance (P = .054. Conclusion At a mean bed occupancy of 84.1%, an Irish RPU can achieve 96.6% appropriate admissions

Water holding capacity and evaporative loss from organic bedding materials used in livestock facilities

Science.gov (United States)

Physical and chemical characteristics of organic bedding materials determine how well they will absorb and retain moisture and may influence the environment in livestock facilities where bedding is used. The objective of this study was to determine water holding capacity (WHC) and rate of evaporativ...

Feasibility Study of a Lunar Analog Bed Rest Model

Science.gov (United States)

Cromwell, Ronita L.; Platts, Steven H.; Yarbough, Patrice; Buccello-Stout, Regina

2010-01-01

The purpose of this study was to determine the feasibility of using a 9.5deg head-up tilt bed rest model to simulate the effects of the 1/6 g load to the human body that exists on the lunar surface. The lunar analog bed rest model utilized a modified hospital bed. The modifications included mounting the mattress on a sled that rolled on bearings to provide freedom of movement. The weight of the sled was off-loaded using a counterweight system to insure that 1/6 body weight was applied along the long axis (z-axis) of the body. Force was verified through use of a force plate mounted at the foot of the bed. A seating assembly was added to the bed to permit periods of sitting. Subjects alternated between standing and sitting positions throughout the day. A total of 35% of the day was spent in the standing position and 65% was spent sitting. In an effort to achieve physiologic fluid shifts expected for a 1/6 G environment, subjects wore compression stockings and performed unloaded foot and ankle exercises. Eight subjects (3 females and 5 males) participated in this study. Subjects spent 13 days in the pre-bed rest phase, 6 days in bed rest and 3 days post bed rest. Subjects consumed a standardized diet throughout the study. To determine feasibility, measures of subject comfort, force and plasma volume were collected. Subject comfort was assessed using a Likert scale. Subjects were asked to assess level of comfort (0-100) for 11 body regions and provide an overall rating. Results indicated minimal to no discomfort as most subjects reported scores of zero. Force measures were performed for each standing position and were validated against subject s calculated 1/6 body weight (r(sup 2) = 0.993). The carbon monoxide rebreathing technique was used to assess plasma volume during pre-bed rest and on the last day of bed rest. Plasma volume results indicated a significant decrease (p = 0.001) from pre to post bed rest values. Subjects lost on average 8.3% (sd = 6.1%) during the

Thymol Hydrogenation in Bench Scale Trickle Bed Reactor

Czech Academy of Sciences Publication Activity Database

Dudas, J.; Hanika, Jiří; Lepuru, J.; Barkhuysen, M.

2005-01-01

Roč. 19, č. 3 (2005), s. 255-262 ISSN 0352-9568 Institutional research plan: CEZ:AV0Z40720504 Keywords : thymol hydrogenation * trickle bed reactor * gas-liquid-solid reaction Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.632, year: 2005

Bed models for solid fuel conversion process in grate-fired boilers

DEFF Research Database (Denmark)

Costa, M.; Massarotti, N.; Indrizzi, V.

2013-01-01

-chemical processes are divided in two successive sections: drying and conversion (which includes pyrolysis, gasification and combustion). The second model is an empirical 1D approach. The two models need input data such as composition, temperature and feeding rate of biomass and primary air. Temperature, species...... to describe the thermo-chemical conversion process of a solid fuel bed in a grate-fired boiler is presented. In this work both models consider the incoming solid fuel as subjected to drying, pyrolysis, gasification and combustion. In the first approach the biomass bed is treated as a 0D system, but the thermo...... concentrations and velocity of the producer gas leaving the fuel bed provided by the two models are compared. A sensitivity analysis with respect to mass flow rate of the primary air is also performed, as well as a further comparison regarding the dependence of the producer gas properties on the initial moisture...

A review of some parameters involved in fluidized bed bioreactors

Energy Technology Data Exchange (ETDEWEB)

Wright, P.C. [School of Chemical Engineering and Industrial Chemistry, The Univ. of New South Wales, Sydney (Australia); Raper, J.A. [School of Chemical Engineering and Industrial Chemistry, The Univ. of New South Wales, Sydney (Australia)

1996-02-01

Three-phase fluidized bed bioreactors have advantages over conventional chemical reaction systems. There is a lack of agreement over most major operational conditions, and a wide range of design variables are open to question. A large body of recent work in the field has been reviewed, with a degree of historical comparison and discussion. It has been found that aspects of fluidized bed biofilm reactors of vital importance include: choice of solid media, gas and liquid loadings, bacterial type and reactor mechanical design. A large proportion of the work in the field of three-phase fluidization is non-biologically specific, or not tested on a bacterially inoculated system. The majority of three-phase fluidized bed bioreactor work is in the field of water treatment. Although this work has highlighted the potential for use of bio-fluidized beds for this application, there are still specific problems hinderin the large scale industrial acceptance of three-phase fluidized bed bioreactors. (orig.)

Current Research at the Endeavour Ridge 2000 Integrated Studies Site

Science.gov (United States)

Butterfield, D. A.; Kelley, D. S.; Ridge 2000 Community, R.

2004-12-01

Integrated geophysical, geological, chemical, and biological studies are being conducted on the Endeavour segment with primary support from NSF, the W.M. Keck Foundation, and NSERC (Canada). The research includes a seismic network, physical and chemical sensors, high-precision mapping and time-series sampling. Several research expeditions have taken place at the Endeavour ISS in the past year. In June 2003, an NSF-sponsored cruise with R.V. al T.G.Thompson/ROV al Jason2 installed microbial incubators in drill-holes in the sides of active sulfide chimneys and sampled rocks, fluids, and microbes in the Mothra and Main Endeavour Field (MEF). In July 2003, with al Thompson/Jason2, an NSF-LEXEN project at Baby Bare on Endeavour east flank conducted sampling through seafloor-penetrating probes, plus time-series sampling of fluids, microbes, and rocks at the MEF. In September 2003, with al Thompson/ROV al ROPOS, the Keck Proto-Neptune project installed a seismic network consisting of 1 broadband and 7 short-period seismometers, installation of chemical/physical sensors and time-series samplers for chemistry and microbiology in the MEF and Clam Bed sites, collection of rocks, fluids, animals, and microbes. In May/June 2004, an NSF-sponsored al Atlantis/Alvin cruise recovered sulfide incubators installed in 2003, redeployed a sulfide incubator, mapped MEF and Mothra vent fields with high-resolution Imagenix sonar, sampled fluids from MEF, Mothra, and Clam Bed, recovered year-long time-series fluid and microbial samplers from MEF and Clam Bed, recovered and installed hot vent temperature-resistivity monitors, cleaned up the MEF and deployed new markers at major sulfide structures. In August 2004, there were two MBARI/Keck-sponsored cruises with R.V. al Western Flyer/ROV al Tiburon. The first cruise completed the seismic network with addition of two more broadband seismometers and serviced all 7 short-period seismometers. al Tiburon then performed microbial and chemical

The development of an integrated multistaged fluid-bed retorting process. Final report, September 1990--August 1994

Energy Technology Data Exchange (ETDEWEB)

Carter, S.D.; Taulbee, D.N.; Stehn, J.L.; Vego, A.; Robl, T.L.

1995-02-01

This summarizes the development of the KENTORT II retorting process, which includes integral fluidized bed zones for pyrolysis, gasification, and combustion of oil shale. Purpose was to design and test the process at the 50-lb/hr scale. The program included bench- scale studies of coking and cracking reactions of shale oil vapors over processed shale particles to address issues of scaleup associated with solid-recycle retorting. The bench-scale studies showed that higher amounts of carbon coverage reduce the rate of subsequent carbon deposition by shale oil vapors onto processed shale particles; however carbon-covered materials were also active in terms of cracking and coking. Main focus was the 50-lb/hr KENTORT II PDU. Cold-flow modeling and shakedown were done before the PDU was made ready for operation. Seven mass-balanced, steady-state runs were completed within the window of design operating conditions. Goals were achieved: shale feedrate, run duration (10 hr), shale recirculation rates (4:1 to pyrolyzer and 10:1 to combustor), bed temperatures (pyrolyzer 530{degree}C, gasifier 750{degree}C, combustor 830{degree}C), and general operating stability. Highest oil yields (up to 109% of Fischer assay) were achieved for runs lasting {ge} 10 hours. High C content of the solids used for heat transfer to the pyrolysis zone contributed to the enhanced oil yield achieved.

Energy generation by air gasification of two industrial plastic wastes in a pilot scale fluidized bed reactor

International Nuclear Information System (INIS)

Arena, Umberto; Di Gregorio, Fabrizio

2014-01-01

Two plastic wastes obtained as co-products from an industrial process were fed in a pilot-scale bubbling fluidized bed gasifier, having an internal diameter of 0.38 m and a maximum thermal output of about 400 kW. The experimental runs were carried out by reaching a condition of thermal and chemical steady state under values of equivalence ratio ranging from 0.2 to 0.3. Olivine, a neo-silicate of Fe and Mg, already tested as a good catalyst for tar removal during gasification of polyolefin plastic wastes, was used as bed material. The results provide the complete composition of the syngas, including the tar, particulate and acid/basic gas contents as well as the chemical and physical characterization of the bed material and entrained fines. The gasification process appears technically feasible, yielding a producer gas of valuable quality for energy applications in an appropriate plant configuration. On the other hand, under the experimental conditions tested, olivine particles show a strongly reduced catalytic activity in all the runs. The differences in the gasification behaviour of the two industrial plastics are explained on the basis of the structure and composition of the wastes, taking also into account the results of a combined material and substance flow analysis. - Highlights: • Pilot-scale investigation of fluidized bed gasification of two industrial plastic wastes. • Tests under conditions of thermal/chemical steady state at various equivalence ratios. • Complete composition of the producer gas, including tar, particulate and acid/basic gases. • Differences in the gasification behaviour of plastic wastes. • Material, substance, and feedstock energy flow analysis for different gasification tests

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

KAUST Repository

Zhao, Zhenlong

2013-01-17

Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

Foundational aspects of the concept of chemical activity

DEFF Research Database (Denmark)

Mayer, Philipp

2015-01-01

The chemical activity of an organic chemical quantifies its potential for spontaneous physicochemical processes, such as diffusion, sorption, and partitioning. For instance, the chemical activity of a sediment contaminant determines its equilibrium partitioning concentration in sediment-dwelling ...

Forces on stationary particles in near-bed turbulent flows

Science.gov (United States)

Schmeeckle, Mark W.; Nelson, Jonathan M.; Shreve, Ronald L.

2007-06-01

In natural flows, bed sediment particles are entrained and moved by the fluctuating forces, such as lift and drag, exerted by the overlying flow on the particles. To develop a better understanding of these forces and the relation of the forces to the local flow, the downstream and vertical components of force on near-bed fixed particles and of fluid velocity above or in front of them were measured synchronously at turbulence-resolving frequencies (200 or 500 Hz) in a laboratory flume. Measurements were made for a spherical test particle fixed at various heights above a smooth bed, above a smooth bed downstream of a downstream-facing step, and in a gravel bed of similarly sized particles as well as for a cubical test particle and 7 natural particles above a smooth bed. Horizontal force was well correlated with downstream velocity and not correlated with vertical velocity or vertical momentum flux. The standard drag formula worked well to predict the horizontal force, but the required value of the drag coefficient was significantly higher than generally used to model bed load motion. For the spheres, cubes, and natural particles, average drag coefficients were found to be 0.76, 1.36, and 0.91, respectively. For comparison, the drag coefficient for a sphere settling in still water at similar particle Reynolds numbers is only about 0.4. The variability of the horizontal force relative to its mean was strongly increased by the presence of the step and the gravel bed. Peak deviations were about 30% of the mean force for the sphere over the smooth bed, about twice the mean with the step, and 4 times it for the sphere protruding roughly half its diameter above the gravel bed. Vertical force correlated poorly with downstream velocity, vertical velocity, and vertical momentum flux whether measured over or ahead of the test particle. Typical formulas for shear-induced lift based on Bernoulli's principle poorly predict the vertical forces on near-bed particles. The

Numerical simulation of a full-loop circulating fluidized bed under different operating conditions

Energy Technology Data Exchange (ETDEWEB)

Xu, Yupeng [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Musser, Jordan M. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Li, Tingwen [National Energy Technology Lab. (NETL), Morgantown, WV (United States); AECOM, Morgantown, WV (United States); Rogers, William A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2017-10-17

Both experimental and computational studies of the fluidization of high-density polyethylene (HDPE) particles in a small-scale full-loop circulating fluidized bed are conducted. Experimental measurements of pressure drop are taken at different locations along the bed. The solids circulation rate is measured with an advanced Particle Image Velocimetry (PIV) technique. The bed height of the quasi-static region in the standpipe is also measured. Comparative numerical simulations are performed with a Computational Fluid Dynamics solver utilizing a Discrete Element Method (CFD-DEM). This paper reports a detailed and direct comparison between CFD-DEM results and experimental data for realistic gas-solid fluidization in a full-loop circulating fluidized bed system. The comparison reveals good agreement with respect to system component pressure drop and inventory height in the standpipe. In addition, the effect of different drag laws applied within the CFD simulation is examined and compared with experimental results.

Effect of humidity on thoron adsorption in activated charcoal bed

International Nuclear Information System (INIS)

Sudeep Kumara, K.; Karunakara, N.; Yashodhara, I.; Sapra, B.K.; Sahoo, B.K.; Gaware, J.J.; Kanse, S.D.; Mayya, Y.S.

2014-01-01

Activated charcoal is a well-known adsorber of 222 Rn and 220 Rn gases. This property can be effectively used for remediation of these gases in the workplaces of uranium and thorium processing facilities. However, the adsorption on charcoal is sensitive to variation in temperature and humidity. The successful designing and characterization of adsorption systems require an adequate understanding of these sensitivities. The study has been carried out towards this end, to delineate the effect of relative humidity on the efficacy of 220 Rn mitigations in a charcoal bed. Air carrying 220 Rn from a Pylon source was passed through a column filled with coconut shell-based granular activated charcoal. The relative humidity of the air was controlled, and the transmission characteristics were examined at relative humidity varying from 45% to 60%. The mitigation factor was found to decrease significantly with an increase of humidity in the air. (author)

Adiabatic Compressed Air Energy Storage with packed bed thermal energy storage

International Nuclear Information System (INIS)

Barbour, Edward; Mignard, Dimitri; Ding, Yulong; Li, Yongliang

2015-01-01

Highlights: • The paper presents a thermodynamic analysis of A-CAES using packed bed regenerators. • The packed beds are used to store the compression heat. • A numerical model is developed, validated and used to simulate system operation. • The simulated efficiencies are between 70.5% and 71.1% for continuous operation. • Heat build-up in the beds reduces continuous cycle efficiency slightly. - Abstract: The majority of articles on Adiabatic Compressed Air Energy Storage (A-CAES) so far have focussed on the use of indirect-contact heat exchangers and a thermal fluid in which to store the compression heat. While packed beds have been suggested, a detailed analysis of A-CAES with packed beds is lacking in the available literature. This paper presents such an analysis. We develop a numerical model of an A-CAES system with packed beds and validate it against analytical solutions. Our results suggest that an efficiency in excess of 70% should be achievable, which is higher than many of the previous estimates for A-CAES systems using indirect-contact heat exchangers. We carry out an exergy analysis for a single charge–storage–discharge cycle to see where the main losses are likely to transpire and we find that the main losses occur in the compressors and expanders (accounting for nearly 20% of the work input) rather than in the packed beds. The system is then simulated for continuous cycling and it is found that the build-up of leftover heat from previous cycles in the packed beds results in higher steady state temperature profiles of the packed beds. This leads to a small reduction (<0.5%) in efficiency for continuous operation

Molecular activation analysis for chemical speciation studies

International Nuclear Information System (INIS)

Chai-Chifang

1998-01-01

The term of Molecular Activation Analysis (MAA) refers to an activation analysis method that is able to provide information about the chemical species of elements in system of interests, though its definition has remained to be assigned. Its development is strongly stimulated by the urgent need to know the chemical species of elements, because the total concentrations are often without any meaning when assessing health or environmental risks of trace elements.In practice, the MAA is a combination of conventional instrumental or radiochemical activation analysis and physical, chemical or biochemical separation techniques. The MAA is able to play a particular role in speciation studies. However, the critical point in the MAA is that it is not permitted to change the primitive chemical species of elements in systems, or the change has to be under control; in the meantime it is not allowed to form the 'new artifact' originally not present in systems. Some practical examples of MAA for chemical species research performed recently in our laboratory will be presented as follows: Chemical species of platinum group elements in sediment; Chemical species of iodine in marine algae; Chemical species of mercury in human tissues; Chemical species of selenium in corn; Chemical species of rare earth elements in natural plant, etc. The merits and limitations of MAA will be described as well. (author)

Fluidised bed cereal cooking

International Nuclear Information System (INIS)

Jenkins, Simon Anthony

2002-01-01

Man has been cooking food for thousands of years for a number of reasons: to improve flavour and palatability, sterilise, increase digestibility, improve texture and colour. Increasingly more advanced techniques are employed today in food production plants to engineer foods with many different properties. With this in mind manufacturers are constantly seeking to improve processing techniques and apply new or different technologies (such as microwaves, RF and extrusion) to develop foods with new properties (like puffed texture starches) and to increase process efficiencies (energy efficiency, water reduction). This thesis reports on work undertaken to demonstrate the potential to achieve high temperature starch conversion of whole wheat grains in a fluidised bed, thereby reducing the amount of water required and processing time. Specifically, wheat from the farm at 14% water content is cooked in a fluidised bed. The fluidised bed heats the wheat quickly by convective heating. In addition, energy can be delivered directly to the grain by microwave heating during fluidisation. Degree of starch conversion is determined by measuring the reduction in size of endotherm of reaction as observed by Differential Scanning Calorimetry. The fluidising gas, processing temperature and starting moisture content were varied in order to investigate their effect on the cooking process. A mathematical model based on energy and species concentration equations was developed to help understand the internal grain processes. The model coupled the thermal energy equation with water diffusion. The effect of water evaporation was represented as a thermal sink in the energy equation. Popular kinetic models from literature were adapted to predict the degree of starch conversion. The model gives solutions consistent with experimental data and physical intuition. A commercial computational fluid dynamics package was used to study simple airflow and particle tracks in the fluidisation column. A

Method for immobilizing particulate materials in a packed bed

Science.gov (United States)

Even, Jr., William R.; Guthrie, Stephen E.; Raber, Thomas N.; Wally, Karl; Whinnery, LeRoy L.; Zifer, Thomas

1999-01-01

The present invention pertains generally to immobilizing particulate matter contained in a "packed" bed reactor so as to prevent powder migration, compaction, coalescence, or the like. More specifically, this invention relates to a technique for immobilizing particulate materials using a microporous foam-like polymer such that a) the particulate retains its essential chemical nature, b) the local movement of the particulate particles is not unduly restricted, c) bulk powder migration and is prevented, d) physical and chemical access to the particulate is unchanged over time, and e) very high particulate densities are achieved. The immobilized bed of the present invention comprises a vessel for holding particulate matter, inlet and an outlet ports or fittings, a loosely packed bed of particulate material contained within the vessel, and a three dimensional porous matrix for surrounding and confining the particles thereby fixing the movement of individual particle to a limited local position. The established matrix is composed of a series of cells or chambers comprising walls surrounding void space, each wall forming the wall of an adjacent cell; each wall containing many holes penetrating through the wall yielding an overall porous structure and allowing useful levels of gas transport.

Forced excitation and active control for the measurement of fluid-elastic forces

International Nuclear Information System (INIS)

Caillaud, Sebastien

1999-01-01

The action of a fluid flow on a tubes bundle is commonly decomposed into a random turbulent excitation and a fluid-elastic excitation. The fluid-elastic forces which are coupled to the tubes movement can be experimentally determined from an analysis of the vibratory response of the structure excited by turbulent forces. For low flow velocities, the turbulent excitation can be insufficient to make the tube significantly vibrate and to permit a correct vibratory analysis. On the opposite side, the structure can become unstable for high flow velocities: the fluid-elastic forces make the fluid-structure damping system fall towards zero. Two experimental methods are proposed in order to extend the considered flow rate. An additional excitation force allows to increase the tube vibration level for improving the signal-noise ratio at low velocities. When the tube is submitted to fluid-elastic instability, an artificial damping contribution by active control allows to stabilize it. Methods are implemented on a flexible tube inserted into rigid tubes bundle water and water-air transverse flows. Two actuator technologies are used: an electromagnetic exciter and piezoelectric actuators. The additional excitation method shows that the fluid-elastic forces remain insignificant at low velocity single phase flow. With the active control method, it is possible to carry out tests beyond the fluid-elastic instability. In two-phase flow, the stabilization of the structure is observed for low vacuum rates. The obtained new results are analyzed with the literature expected results in terms of fluid-elastic coupling and turbulent excitation. (author) [fr

Technical and economic assessment of fluidized-bed-augmented compressed-air energy-storage system: system load following capability

Energy Technology Data Exchange (ETDEWEB)

Lessard, R.D.; Blecher, W.A.; Merrick, D.

1981-09-01

The load-following capability of fluidized bed combustion-augmented compressed air energy storage systems was evaluated. The results are presented in two parts. The first part is an Executive Summary which provides a concise overview of all major elements of the study including the conclusions, and, second, a detailed technical report describing the part-load and load following capability of both the pressurized fluid bed combustor and the entire pressurized fluid bed combustor/compressed air energy storage system. The specific tasks in this investigation were to: define the steady-state, part-load operation of the CAES open-bed PFBC; estimate the steady-state, part-load performance of the PFBC/CAES system and evaluate any possible operational constraints; simulate the performance of the PFBC/CAES system during transient operation and assess the load following capability of the system; and establish a start-up procedure for the open-bed PFBC and evaluate the impact of this procedure. The conclusions are encouraging and indicate that the open-bed PFBC/CAES power plant should provide good part-load and transient performance, and should have no major equipment-related constraints, specifically, no major problems associated with the performance or design of either the open-end PFBC or the PFBC/CAES power plant in steady-state, part-load operation are envisioned. The open-bed PFBC/CAES power plant would have a load following capability which would be responsive to electric utility requirements for a peak-load power plant. The open-bed PFBC could be brought to full operating conditions within 15 min after routine shutdown, by employing a hot-start mode of operation. The PFBC/CAES system would be capable of rapid changes in output power (12% of design load per minute) over a wide output power range (25% to 100% of design output). (LCL)

The effect of a crosslinking chemical reaction on pattern formation in viscous fingering of miscible fluids in a Hele-Shaw cell

Science.gov (United States)

Bunton, Patrick H.; Tullier, Michael P.; Meiburg, Eckart; Pojman, John A.

2017-10-01

Viscous fingering can occur in fluid motion whenever a high mobility fluid displaces a low mobility fluid in a Darcy type flow. When the mobility difference is primarily attributable to viscosity (e.g., flow between the two horizontal plates of a Hele-Shaw cell), viscous fingering (VF) occurs, which is sometimes termed the Saffman-Taylor instability. Alternatively, in the presence of differences in density in a gravity field, buoyancy-driven convection can occur. These instabilities have been studied for decades, in part because of their many applications in pollutant dispersal, ocean currents, enhanced petroleum recovery, and so on. More recent interest has emerged regarding the effects of chemical reactions on fingering instabilities. As chemical reactions change the key flow parameters (densities, viscosities, and concentrations), they may have either a destabilizing or stabilizing effect on the flow. Hence, new flow patterns can emerge; moreover, one can then hope to gain some control over flow instabilities through reaction rates, flow rates, and reaction products. We report effects of chemical reactions on VF in a Hele-Shaw cell for a reactive step-growth cross-linking polymerization system. The cross-linked reaction product results in a non-monotonic viscosity profile at the interface, which affects flow stability. Furthermore, three-dimensional internal flows influence the long-term pattern that results.

Oxygen Carrier Aided Combustion (OCAC of Wood Chips in a Semi-Commercial Circulating Fluidized Bed Boiler Using Manganese Ore as Bed Material