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Sample records for stage pressurized fluidized

  1. Pressurized Fluidized Bed Combustion of Sewage Sludge

    Science.gov (United States)

    Suzuki, Yoshizo; Nojima, Tomoyuki; Kakuta, Akihiko; Moritomi, Hiroshi

    A conceptual design of an energy recovering system from sewage sludge was proposed. This system consists of a pressurized fluidized bed combustor, a gas turbine, and a heat exchanger for preheating of combustion air. Thermal efficiency was estimated roughly as 10-25%. In order to know the combustion characteristics of the sewage sludge under the elevated pressure condition, combustion tests of the dry and wet sewage sludge were carried out by using laboratory scale pressurized fluidized bed combustors. Combustibility of the sewage sludge was good enough and almost complete combustion was achieved in the combustion of the actual wet sludge. CO emission and NOx emission were marvelously low especially during the combustion of wet sewage sludge regardless of high volatile and nitrogen content of the sewage sludge. However, nitrous oxide (N2O) emission was very high. Hence, almost all nitrogen oxides were emitted as the form of N2O. From these combustion tests, we judged combustion of the sewage sludge with the pressurized fluidized bed combustor is suitable, and the conceptual design of the power generation system is available.

  2. Staged fluidized-bed coal combustor for boiler retrofit

    International Nuclear Information System (INIS)

    Rehmat, A.; Dorfman, L.; Shibayama, G.; Waibel, R.

    1991-01-01

    The Advanced Staged Fluidized-Bed Coal Combustion System (ASC) is a novel clean coal technology for either coal-fired repowering of existing boilers or for incremental power generation using combined-cycle gas turbines. This new technology combines staged combustion for gaseous emission control, in-situ sulfur capture, and an ash agglomeration/vitrification process for the agglomeration/vitrification of ash and spent sorbent, thus rendering solid waste environmentally benign. The market for ASC is expected to be for clean coal-fired repowering of generating units up to 250 MW, especially for units where space is limited. The expected tightening of the environmental requirements on leachable solids residue by-products could considerably increase the marketability for ASC. ASC consists of modular low-pressure vessels in which coal is partially combusted and gasified using stacked fluidized-bed processes to produce low-to-medium-Btu, high-temperature gas. This relatively clean fuel gas is used to repower/refuel existing pulverized-coal, natural gas, or oil-fired boilers using bottom firing and reburning techniques. The benefits of ASC coal-fired repowering include the ability to repower boilers without obtaining additional space while meeting the more stringent environmental requirements of the future. Low NO x , SO x , and particulate levels are expected while a nonleachable solid residue with trace metal encapsulation is produced. ASC also minimizes boiler modification and life-extension expenditures. Repowered efficiencies can be restored to the initial operating plant efficiency, and the existing boiler capacity can be increased by 10%. Preliminary cost estimates indicate that ASC will have up to a $250/kW capital cost advantage over existing coal-fired repowering options. 4 figs., 4 tabs

  3. Development of second-generation pressurized fluidized bed combustion process

    Energy Technology Data Exchange (ETDEWEB)

    Wolowodiuk, W.; Robertson, A. [Foster Wheeler Development Corp., Livingston, NJ (United States); Bonk, D. [Dept. of Energy, Morgantown, WV (United States)

    1995-12-01

    Under the sponsorship of the United States Department of Energy, Foster Wheeler Development Corporation, and its team members, Westinghouse, Gilbert/Commonwealth, and the Institute of Gas Technology are developing second-generation pressurized fluidized bed combustion technology capable of achieving net plant efficiency in excess of 45 percent based on the higher heating value of the coal. A three-phase program entails design and costing of a 500 MWe power plant and identification of developments needed to commercialize this technology (Phase 1), testing of individual components (Phase 2), and finally testing these components in an integrated mode (Phase 3). This paper briefly describes the results of the first two phases as well as the progress on the third phase. Since other projects which use the same technology are in construction or in negotiation stages-namely, the Power System Development Facility and the Four Rivers Energy Modernization Projects-brief descriptions of these are also included.

  4. Physical Characteristics of Fluidized Beds via Pressure Fluctuation Analysis

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar

    2008-01-01

    Roč. 54, č. 7 (2008), s. 1761-1769 ISSN 0001-1541 R&D Projects: GA AV ČR IAA400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : gas-solid fluidization * pressure fluctuations * fluctuation characteristics Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.883, year: 2008

  5. Pressurized fluidized-bed combustion technology exchange workshop

    Energy Technology Data Exchange (ETDEWEB)

    ,

    1980-04-01

    The pressurized fluidized-bed combustion technology exchange workshop was held June 5 and 6, 1979, at The Meadowlands Hilton Hotel, Secaucus, New Jersey. Eleven papers have been entered individually into EDB and ERA. The papers include reviews of the US DOE and EPRI programs in this area and papers by Swedish, West German, British and American organizations. The British papers concern the joint program of the USA, UK and FRG at Leatherhead. The key factor in several papers is the use of fluidized bed combustors, gas turbines, and steam turbines in combined-cycle power plants. One paper examines several combined-cycle alternatives. (LTN)

  6. Multiscale probability distribution of pressure fluctuations in fluidized beds

    International Nuclear Information System (INIS)

    Ghasemi, Fatemeh; Sahimi, Muhammad; Reza Rahimi Tabar, M; Peinke, Joachim

    2012-01-01

    Analysis of flow in fluidized beds, a common chemical reactor, is of much current interest due to its fundamental as well as industrial importance. Experimental data for the successive increments of the pressure fluctuations time series in a fluidized bed are analyzed by computing a multiscale probability density function (PDF) of the increments. The results demonstrate the evolution of the shape of the PDF from the short to long time scales. The deformation of the PDF across time scales may be modeled by the log-normal cascade model. The results are also in contrast to the previously proposed PDFs for the pressure fluctuations that include a Gaussian distribution and a PDF with a power-law tail. To understand better the properties of the pressure fluctuations, we also construct the shuffled and surrogate time series for the data and analyze them with the same method. It turns out that long-range correlations play an important role in the structure of the time series that represent the pressure fluctuation. (paper)

  7. Coal gasification fluidized bed (Winkler gasification) under pressure

    International Nuclear Information System (INIS)

    Anwer, J.; Boegner, F.

    1976-01-01

    Due to the 'oil crisis', the gasification of lignite and coal for the production of fuel and synthetic gas has reached increased importance. The present state of the Winkler gasification which has successfully operated for a long time is described. After the basic design of a Winkler gasification plant, the various chemical engineering problems are shown: the design characteristics of a fluidized bed, the reaction kinetics, the dependance of the products on the gasification pressure, and the economics of the process. Finally, the development trend in the USA and the future possibility of heating by nuclear heat is dealt with. (orig.) [de

  8. Analysis of the pressure fluctuations in binary solids circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yongguo [School of Mechanical and Power Engineering, Shanghai JiaoTong University, Dongchuan Road 800, Shanghai 200240 (China)]. E-mail: yongguo_chen@hotmail.com; Tian Ziping [School of Mechanical and Power Engineering, Shanghai JiaoTong University, Dongchuan Road 800, Shanghai 200240 (China); Miao Zhengqing [School of Mechanical and Power Engineering, Shanghai JiaoTong University, Dongchuan Road 800, Shanghai 200240 (China)

    2006-03-15

    Pressure fluctuations are often selected to analyze the dynamic changes in the fluidized bed. Many researchers in the field of fluidization have adopted many methods to analyze the pressure signals in fluidized beds, such as statistical analysis (in time domain), frequency analysis (in frequency domain) and non-linear analysis (such as chaotic method). There are many literatures concentrated on statistical analysis in the fluidization field since this method can display the distribution density of the pressure fluctuations. In this study, the pressure fluctuations on the bed wall at different bed heights in the cold two dimensional (2-D) circulating fluidized bed (200 x 30 x 1200 mm{sup 3}) were sampled. The colophony, millet and 20% millet plus 80% colophony were selected as bed materials. The pressure signals were analyzed by means of statistical methods. The correlation equations between the pressure signals and fluidization parameters were obtained under different operational conditions. Finally, comparisons between the single solid and binary solids 2-D circulating fluidized beds were investigated deeply. Two parameters, K {sub 1} (=0.54(u - u {sub mf}){sup 0.4} h {sup 0.8}/g {sup 0.2}) and K {sub 2} (={sigma} {sub b}/({rho} {sub s} g(1 - {epsilon} {sub mf}))), were selected to characterize the fluidization mechanism. It was found that the relationships between K {sub 2} and K {sub 1} among the single solid and binary solids circulating fluidized beds vary a great deal.

  9. Population balance modelling and multi-stage optimal control of a pulsed spray fluidized bed granulation.

    Science.gov (United States)

    Liu, Huolong; Li, Mingzhong

    2014-07-01

    In this work, one-dimensional population balance models (PBMs) have been developed to model a pulsed top-spray fluidized bed granulation. The developed PBMs have linked the key binder solution spray operating factors of the binder spray rate, atomizing air pressure and pulsed frequency of spray with the granule properties to predict granule growth behaviour in the pulsed spray fluidized bed granulation process at different operating conditions with accuracy. A multi-stage open optimal control strategy based on the developed PBMs was proposed to reduce the model mismatch, in which through adjusting the trajectory of the evolution of the granule size distribution at predefined sample intervals, to determine the optimal operating variables related to the binder spray including the spray rate of binding liquid, atomizing air pressure and pulsed frequency of spray. The effectiveness of the proposed modelling and multi-stage open optimal control strategies has been validated by experimental and simulation tests. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Technical evaluation: pressurized fluidized-bed combustion technology

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S A; Vogel, G J; Gehl, S M; Hanway, Jr, J E; Henry, R F; Parker, K M; Smyk, E B; Swift, W M; Podolski, W F

    1982-04-01

    The technology of pressurized fluidized-bed combustion, particularly in its application to a coal-burning combined-cycle plant, is evaluated by examining the technical status of advanced-concept plant components - boiler system (combustor, air-handling and air-injection equipment, and heat exchangers); solids handling, injection, and ejection system; hot-gas cleanup equipment; instrumentation/control system; and the gas turbine - along with materials of plant construction. Environmental performance as well as energy efficiency are examined, and economic considerations are reviewed briefly. The evaluation concludes with a broad survey of the principal related research and development programs in the United States and other countries, a foreview of the most likely technological developments, and a summary of unresolved technical issues and problems.

  11. Dehydration Behaviour of Borax Pentahydrate to Anhydrous Borax by Multi-Stage Heating in a Fluidized

    OpenAIRE

    ŞAHİN, Ömer

    2002-01-01

    In order to optimize the anhydrous borax process in a fluidized bed calcinator, it is absolutely necessary to study the dehydration behaviour of borax pentahydrate. It was found that the basic feature of the dehydration of borax pentahydrate to anhydrous borax is concerned with the conditions employed. The bulk density and sodium borate content of the end product were determined to be a function of number of stages of temperature of the dehydration period in the fluidized bed. It...

  12. Analysis of the pressure fluctuations in binary solids circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yong-guo; Tian, Zi-ping; Miao, Zheng-qing [School of Mechanical and Power Engineering, Shanghai JiaoTong University, Dongchuan Road 800, Shanghai 200240 (China)

    2006-03-15

    Pressure fluctuations are often selected to analyze the dynamic changes in the fluidized bed. Many researchers in the field of fluidization have adopted many methods to analyze the pressure signals in fluidized beds, such as statistical analysis (in time domain), frequency analysis (in frequency domain) and non-linear analysis (such as chaotic method). There are many literatures concentrated on statistical analysis in the fluidization field since this method can display the distribution density of the pressure fluctuations. In this study, the pressure fluctuations on the bed wall at different bed heights in the cold two dimensional (2-D) circulating fluidized bed (200x30x1200mm{sup 3}) were sampled. The colophony, millet and 20% millet plus 80% colophony were selected as bed materials. The pressure signals were analyzed by means of statistical methods. The correlation equations between the pressure signals and fluidization parameters were obtained under different operational conditions. Finally, comparisons between the single solid and binary solids 2-D circulating fluidized beds were investigated deeply. Two parameters, K{sub 1} (=0.54(u-u{sub mf}){sup 0.4}h{sup 0.8}/g{sup 0.2}) and K{sub 2} (={sigma}{sub b}/(r{sub s}g(1-{epsilon}{sub mf}))), were selected to characterize the fluidization mechanism. It was found that the relationships between K{sub 2} and K{sub 1} among the single solid and binary solids circulating fluidized beds vary a great deal. (author)

  13. Temperature and pressure distributions in a 400 kW{sub t} fluidized bed straw gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Erguedenler, A.; Ghaly, A.E.; Hamdullahpur, F. [Technical Univ. of Nova Scotia, Halifax (Canada)

    1993-12-31

    The temperature and pressure distribution characteristics of a 400 kW (thermal) dual-distributor type fluidized bed straw gasifier were investigated. The effects of the bed height, equivalence ratio (actual air-fuel ratio:stoichiometric air-fuel ratio) and fluidization velocity on the temperature and pressure variations in the gasifier were studied. Generally, the bed temperature reached the steady state condition within 15--20 minutes. The average temperature of the dense bed ranged from 649{degrees}C to 875{degrees}C depending on the levels of operating parameters used. The bed temperature increased linearly with increases in the equivalence ratio, higher bed temperatures were observed with lower bed height and no clear trend for the bed temperature with respect to variations in fluidization velocity was observed. The bed height, equivalence ratio and fluidization velocity affected the pressure drop in the fluidized bed gasifier. Increasing the fluidization velocity and/or decreasing the equivalence ratio resulted in higher pressure drops in the dense bed and the freeboard regions whereas increasing the bed height increased the pressure drop only in the dense bed.

  14. Pressurized fluidized-bed hydroretorting of Eastern oil shales

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Mensinger, M.C.; Rue, D.M.; Lau, F.S. (Institute of Gas Technology, Chicago, IL (United States)); Schultz, C.W. (Alabama Univ., University, AL (United States)); Parekh, B.K. (Kentucky Univ., Lexington, KY (United States)); Misra, M. (Nevada Univ., Reno, NV (United States)); Bonner, W.P. (Tennessee Technological Univ., Cookeville, TN (United States))

    1992-11-01

    The Devonian oil shales of the Eastern United States are a significant domestic energy resource. The overall objective of the multi-year program, initiated in October 1987 by the US Department of Energy is to perform the research necessary to develop the Pressurized Fluidized-Bed Hydroretorting (PFH) process for producing oil from Eastern oil shales. The program also incorporates research on technologies in areas such as raw shale preparation, beneficiation, product separation, and waste disposal that have the potential of improving the economics and/or environmental acceptability of recovering oil from oil shales using the PFH process. The results of the original 3-year program, which was concluded in May 1991, have been summarized in a four-volume final report published by IGT. DOE subsequently approved a 1-year extension to the program to further develop the PFH process specifically for application to beneficiated shale as feedstock. Studies have shown that beneficiated shale is the preferred feedstock for pressurized hydroretorting. The program extension is divided into the following active tasks. Task 3. testing of process improvement concepts; Task 4. beneficiation research; Task 5. operation of PFH on beneficiated shale; Task 6. environmental data and mitigation analyses; Task 7. sample procurement, preparation, and characterization; and Task 8. project management and reporting. In order to accomplish all the program objectives, the Institute of Gas Technology (IGT), the prime contractor, worked with four other institutions: the University of Alabama/Mineral Resources Institute (MRI), the University of Kentucky Center for Applied Energy Research (UK-CAER), the University of Nevada (UN) at Reno, and Tennessee Technological University (TTU). This report presents the work performed during the program extension from June 1, 1991 through May 31, 1992.

  15. Time series analysis of pressure fluctuation in gas-solid fluidized beds

    Directory of Open Access Journals (Sweden)

    C. Alberto S. Felipe

    2004-09-01

    Full Text Available The purpose of the present work was to study the differentiation of states of typical fluidization (single bubble, multiple bubble and slugging in a gas-solid fluidized bed, using spectral analysis of pressure fluctuation time series. The effects of the method of measuring (differential and absolute pressure fluctuations and the axial position of the probes in the fluidization column on the identification of each of the regimes studied were evaluated. Fast Fourier Transform (FFT was the mathematic tool used to analysing the data of pressure fluctuations, which expresses the behavior of a time series in the frequency domain. Results indicated that the plenum chamber was a place for reliable measurement and that care should be taken in measurement in the dense phase. The method allowed fluid dynamic regimes to be differentiated by their dominant frequency characteristics.

  16. Combustion of coked sand in a two-stage fluidized bed system

    Energy Technology Data Exchange (ETDEWEB)

    Coronella, C.J.; Seader, J.D. (University of Utah, Salt Lake City, UT (USA). Dept. of Chemical Engineering)

    1992-02-01

    An advanced multiple-stage fluidized bed reactor system has been devised for the energy-efficient extraction and conversion, from tar sand, of bitumen into synthetic crude oil. The reactor consists of four fluidized beds arranged as stages in series with respect to flow of sand. In the first stage, tar sands are heated, causing the bitumen to pyrolyse into coke, which is deposited on the sand, and gas, which is mostly condensed into oil. The coke is partially combusted with air or enriched oxygen in the second stage, which is thermally coupled to the first stage by multiple vertical heat pipes. Combustion is completed adiabatically in the third stage and heat recovery from the sand is carried out in the fourth stage. By conducting the coke combustion in two stages in this manner, the overall reactor residence time to produce clean sand is greatly reduced from that for a single combustion stage. Laboratory experimental studies have confirmed the ability to operate and control the two thermally coupled stages. The two-phase bubbling bed model of Grace, amended to account for bubble growth in the axial direction, has been adopted to model the mass transfer and fluid mechanics of the fluidized beds. The model for the first and second combustion stages is complete. Predictions for exit reactor conditions at various operating conditions are in reasonable agreement with experimental observations. The operating parameters have been found to exert a much greater influence on the predictions of the model than do the values of the physical parameters, indicating a desirable degree of reactor stability. Extension of the model to the pyrolysis and heat recovery stages will permit the optimization of the reactor configuration and operating conditions. 26 refs., 6 figs.

  17. Fluidization quality analyzer for fluidized beds

    Science.gov (United States)

    Daw, C.S.; Hawk, J.A.

    1995-07-25

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

  18. Development of a pressurized fluidized-bed biomass gsifier to produce substitute fuels

    Science.gov (United States)

    Babu, S. P.; Onischak, M.; Kosowski, G.

    The Institute of Gas technology (IGT) is conducting a program to convert forest and crop residues to substitute fuel in a pressurized fluidized-bed biomass gasifier. The process is designed for operation at pressures up to 2.17 MPa (315 psia) and temperatures up to 1255 K (1800 F). Various goals for synthesis or fuel gas processes are being pursued to develop an efficient process. Some of these goals are to maximize the throughput, the amount, and the quality of the gas, while minimizing both the amount of the feedstock preparation needed and the formation of condensible compounds that require by-product disposal and process wastewater treatment. The process development results obtained from fluidization biomass devolatilization, and char gasification studies were used to design a 30/5-cm (12-inch) ID adiabatic fluidized-bed gasification process development unit (PDU), capable of handling up to 455 kg (1000 lb) of biomass per hour.

  19. Modelling of NOx emissions from pressurized fluidized bed combustion - A parameter study

    DEFF Research Database (Denmark)

    Jensen, Anker; Johnsson, Jan Erik

    1997-01-01

    Simulations with a mathematical model of a pressurized bubbling fluidized-bed combustor (PFBC) combined with a kinetic model for NO formation and reduction are reported. The kinetic model for NO formation and reduction considers NO and NH3 as the fixed nitrogen species, and includes homogeneous r...

  20. Development of pressurized internally circulating fluidized bed combustion technology; Kaatsu naibu junkan ryudosho boiler no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, I. [Center for Coal Utilization, Japan, Tokyo (Japan); Nagato, S.; Toyoda, S. [Ebara Corp., Tokyo (Japan)

    1996-09-01

    The paper introduced support research on element technology needed for the design of hot models of the pressurized internally circulating fluidized bed combustion boiler in fiscal 1995 and specifications for testing facilities of 4MWt hot models after finishing the basic plan. The support research was conduced as follows: (a) In the test for analysis of cold model fluidization, it was confirmed that each characteristic value of hot models is higher than the target value. Further, calculation parameters required for computer simulation were measured and data on the design of air diffusion nozzle for 1 chamber wind box were sampled. (b) In the CWP conveyance characteristic survey, it was confirmed that it is possible to produce CWP having favorable properties. It was also confirmed that favorable conveyability can be maintained even if the piping size was reduced down to 25A. (c) In the gas pressure reducing test, basic data required for the design of gas pressure reducing equipment were sampled. Specifications for the fluidized bed combustion boiler of hot models are as follows: evaporation amount: 3070kg/h, steam pressure: 1.77MPa, fuel supply amount: 600kg-coal/h, boiler body: cylinder shape water tube internally circulating fluidized bed combustion boiler. 4 refs., 4 figs.

  1. Use of Pressure Fluctuations to Determine Online the Regime of Gas-Solids Suspensions from Incipient Fluidization to Transport

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar; Svoboda, Karel

    2009-01-01

    Roč. 48, č. 14 (2009), s. 6830-6835 ISSN 0888-5885 R&D Projects: GA AV ČR IAA400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized beds * fluidization regimes * pressure fluctuations Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.758, year: 2009

  2. 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.

  3. Pressure drop across the distributor in fluidized beds with regular and irregular distributor design

    International Nuclear Information System (INIS)

    Ho, T.C.; Chen, T.K.; Hopper, J.R.

    1984-01-01

    The characteristics of the distributor pressure drop in a fluidized bed corresponding to perforated distributor plates with regular and irregular distributor design were studied. Distributor pressure drops were measured in an empty bed and beds with different fluidizing particles or bed heights. The design variables tested included the open area ratio, hole size, hole lay-out, plate thickness and design irregularity. The characteristics of distributor pressure drop corresponding to abnormal operating conditions, i.e., hole blocking and channeling, were also examined. The results indicate that the open area ratio is the most critical parameter governing the plate pressure drop for a regular distributor and that the design irregularity has a strong effect on the distributor behavior when particles are present. The study has given rise to a criterion for uniform air distribution across the distributor holes

  4. Development program on pressurized fluidized-bed combustion. Annual report, July 1, 1974--June 30, 1975

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, G.J.; Cunningham, P.; Fischer, J.

    1975-07-01

    The feasibility of using fluidized-bed combustors in power and steam plants is being evaluated. The concept involves burning fuels such as coal in a fluidized bed of either a naturally occurring, calcium-containing limestone or dolomite or in a synthetically prepared calcium-containing stone. The calcium oxide in the stone reacts with the sulfur released during combustion to form calcium sulfate, which remains in the bed, thus decreasing the level of SO/sub 2/ in the flue gas. Levels of NO/sub x/ in the flue gas are also low. The effect of operating variables and type of stone on the levels of SO/sub 2/ and NO/sub x/ is being determined. Behavior of trace elements during combustion has been preliminarily evaluated. The properties of a fluidized bed at minimum fluidization at different temperatures and pressures have been determined. The CaSO/sub 4/ produced in the combustion process is regenerated to CaO for reuse in the combustor by reductive decomposition at 1095/sup 0/C (2000/sup 0/F). The effects of operating variables on sulfur release during regeneration are being evaluated. Another regeneration process, solid-solid reaction of CaSO/sub 4/ with CaS, is also being investigated. Fundamental investigations of the kinetics of sulfation and regeneration reactions for the natural and synthetic stones are continuing. A model for the sulfation reaction is presented. The status of the new combustor andancillary regenerator equipment is discussed. (auth)

  5. Two stage, low temperature, catalyzed fluidized bed incineration with in situ neutralization for radioactive mixed wastes

    International Nuclear Information System (INIS)

    Wade, J.F.; Williams, P.M.

    1995-01-01

    A two stage, low temperature, catalyzed fluidized bed incineration process is proving successful at incinerating hazardous wastes containing nuclear material. The process operates at 550 degrees C and 650 degrees C in its two stages. Acid gas neutralization takes place in situ using sodium carbonate as a sorbent in the first stage bed. The feed material to the incinerator is hazardous waste-as defined by the Resource Conservation and Recovery Act-mixed with radioactive materials. The radioactive materials are plutonium, uranium, and americium that are byproducts of nuclear weapons production. Despite its low temperature operation, this system successfully destroyed poly-chlorinated biphenyls at a 99.99992% destruction and removal efficiency. Radionuclides and volatile heavy metals leave the fluidized beds and enter the air pollution control system in minimal amounts. Recently collected modeling and experimental data show the process minimizes dioxin and furan production. The report also discusses air pollution, ash solidification, and other data collected from pilot- and demonstration-scale testing. The testing took place at Rocky Flats Environmental Technology Site, a US Department of Energy facility, in the 1970s, 1980s, and 1990s

  6. Improved PFB operations - 400-hour turbine test results. [Pressurized Fluidized Bed

    Science.gov (United States)

    Rollbuhler, R. J.; Benford, S. M.; Zellars, G. R.

    1980-01-01

    The paper deals with a 400-hr small turbine test in the effluent of a pressurized fluidized bed (PFB) at an average temperature of 770 C, an average relative gas velocity of 300 m/sec, and average solid loadings of 200 ppm. Consideration is given to combustion parameters and operating procedure as well as to the turbine system and turbine test operating procedures. Emphasis is placed on erosion/corrosion results.

  7. Comparison of air-fluidized therapy with other support surfaces used to treat pressure ulcers in nursing home residents.

    Science.gov (United States)

    Ochs, Rachel F; Horn, Susan D; van Rijswijk, Lia; Pietsch, Catherine; Smout, Randall J

    2005-02-01

    To provide empirical evidence comparing pressure ulcer healing rates between different support surfaces, data were analyzed from eligible residents with pressure ulcers (N = 664) enrolled in the National Pressure Ulcer Long-Term Care Study, a retrospective pressure ulcer prevention and treatment study. Support surfaces were categorized as: Group 1 (static overlays and replacement mattresses), Group 2 (low-air-loss beds, alternating pressure, and powered/non-powered overlays/mattresses), and Group 3 (air-fluidized beds). Calculation of healing rates, using the largest ulcer from each resident, found mean healing rates greatest for air-fluidized therapy (Group 3) (mean = 5.2 cm(2)/week) versus Group 1 (mean =1.5 cm(2)/week) and Group 2 (mean = 1.8 cm(2)/week) surfaces (P = 0.007). Healing rates also were assessed using 7- to 10-day "episodes"; each ulcer generated separate episode(s) that included all ulcers when residents had multiple ulcers. Mean healing rates were significantly greater for Stage III/IV ulcers on Group 3 surfaces (mean = 3.1 cm(2)/week) versus Group 1 (mean = 0.6 cm(2)/week) and Group 2 (mean = 0.7 cm(2)/week) surfaces (Group 2 versus Group 3: P = 0.0211). This finding persisted for ulcers with comparable initial baseline areas (20 cm(2) to 75 cm(2)) on Group 2 and Group 3 surfaces; healing improved on Group 3 surfaces (+2.3 cm(2)/week) versus Group 2 surfaces (-2.1 cm(2)/week, P = 0.0399). Residents on Group 3 (6 out of 82; 7.3%) and Group 1 (47 out of 461; 10.2%) surfaces had fewer hospitalizations and emergency room visits than those on Group 2 surfaces (23 out of 121; 19.0%, P = 0.01) despite significantly greater illness in residents on Group 2 and 3 versus Group 1 surfaces (P is less than 0.0001). Despite limitations inherent in retrospective studies, ulcers on Group 3 surfaces versus Groups 1 and Group 2 surfaces had statistically significant faster healing rates (particularly for Stage III/IV ulcers) with significantly fewer

  8. Performance of a pilot-scale, steam-blown, pressurized fluidized bed biomass gasifier

    Science.gov (United States)

    Sweeney, Daniel Joseph

    With the discovery of vast fossil resources, and the subsequent development of the fossil fuel and petrochemical industry, the role of biomass-based products has declined. However, concerns about the finite and decreasing amount of fossil and mineral resources, in addition to health and climate impacts of fossil resource use, have elevated interest in innovative methods for converting renewable biomass resources into products that fit our modern lifestyle. Thermal conversion through gasification is an appealing method for utilizing biomass due to its operability using a wide variety of feedstocks at a wide range of scales, the product has a variety of uses (e.g., transportation fuel production, electricity production, chemicals synthesis), and in many cases, results in significantly lower greenhouse gas emissions. In spite of the advantages of gasification, several technical hurdles have hindered its commercial development. A number of studies have focused on laboratory-scale and atmospheric biomass gasification. However, few studies have reported on pilot-scale, woody biomass gasification under pressurized conditions. The purpose of this research is an assessment of the performance of a pilot-scale, steam-blown, pressurized fluidized bed biomass gasifier. The 200 kWth fluidized bed gasifier is capable of operation using solid feedstocks at feedrates up to 65 lb/hr, bed temperatures up to 1600°F, and pressures up to 8 atm. Gasifier performance was assessed under various temperatures, pressure, and feedstock (untreated woody biomass, dark and medium torrefied biomass) conditions by measuring product gas yield and composition, residue (e.g., tar and char) production, and mass and energy conversion efficiencies. Elevated temperature and pressure, and feedstock pretreatment were shown to have a significant influence on gasifier operability, tar production, carbon conversion, and process efficiency. High-pressure and temperature gasification of dark torrefied biomass

  9. Studies on nitrogen oxides (NOx and N2O) in pressurized fluidized bed combustion

    International Nuclear Information System (INIS)

    Lu Yong

    1998-01-01

    This thesis describes the experimental studies of nitrogen oxide (NO, NO 2 , N 2 O) emissions in pressurized fluidized bed combustion (PFBC). In the first part of the thesis the background and the objectives of this study are introduced. The second part summarizes the fundamental knowledge about the formation and destruction of nitrogen oxides in coal combustion, particularly in the conditions of PFBC. The instrumentation of test facilities, measurement and data analysis is described in the third part. Then the most important experimental results follow in the next parts. The forth part describes the results from a PFBC test rig and an empirical modelling for predicting the emissions of NO x and N 2 O. Finally, the fundamental work on coal combustion and fuel nitrogen conversion in a PFBC batch reactor is presented. These studies clearly confirm the potential of PFBC technology in the control nitrogen of oxide emissions. The research in the test rig was concentrated on determining the effects of process parameters on the emissions of nitrogen oxides with different fuels. Another objective was to examine the reduction of nitrogen oxides with the control methods in PFBC conditions, including ammonia injection and air staging combustion for reducing NO, and high temperature operations for reducing N 2 0. The results indicate that pressurized operation suppresses the conversion of fuel-N to nitrogen oxides and favors with employing the reduction methods for further nitrogen oxide reduction, for instance the temperature window of NO reduction with ammonia injection has been found to be widened to even lower temperature range. Maximum reductions of 80-85 % with ammonia injection and 75-80 % with air staging combustion were achieved in the conditions examined. Considerably low emissions of N 2 O ( 2 O control, and thermal decomposition proved to be the laming pathway of N 2 O destruction in PFBC. In the examined pressure range, increasing pressure causes a decrease of NO

  10. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Archie Robertson

    2003-10-29

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the July 1--September 30, 2003 time period.

  11. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2003-01-30

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1--December 31, 2002 time period.

  12. DEVELOPMENT OF PRESSURIZED CIRCULATING FLUIDIZED BED PARTIAL GASIFICATION MODULE (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Archie Robertson

    2003-07-23

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the April 1--June 30, 2003 time period.

  13. Development of Pressurized Circulating Fluidized Bed Partial Gasification Module (PGM)

    Energy Technology Data Exchange (ETDEWEB)

    A. Robertson

    2003-12-31

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building bock that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the October 1 - December 31, 2003 time period.

  14. A new model for coal gasification on pressurized bubbling fluidized bed gasifiers

    International Nuclear Information System (INIS)

    Sánchez, Cristian; Arenas, Erika; Chejne, Farid; Londoño, Carlos A.; Cisneros, Sebastian; Quintana, Juan C.

    2016-01-01

    Highlights: • A new model was proposed for the simulation of fluidized bed reactors. • The model was validated against experimental data found in the literature. • The model was compared and found to be superior to other models reported in the literature. • Effects of pressure, temperature, steam/coal and air/coal ratios over gas composition were studied. - Abstract: Many industries have taken interest in the use of coal gasification for the production of chemicals and fuels. This gasification can be carried out inside a fluidized bed reactor. This non-ideal reactor is difficult to predict due to the complex physical phenomena and the different chemical changes that the feedstock undergoes. The lack of a good model to simulate the reactor’s behavior produces less efficient processes and plant designs. Various approaches to the proper simulation of such reactor have been proposed. In this paper, a new model is developed for the simulation of a pressurized bubbling fluidized bed (PBFB) gasifier that rigorously models the physical phenomena and the chemical changes of the feedstock inside the reactor. In the model, the reactor is divided into three sections; devolatilization, volatile reactions and combustion-gasification. The simulation is validated against experimental data reported in the literature and compared with other models proposed by different authors; once the model is validated, the dependence of the syngas composition on operational pressure, temperature, steam/coal and air/coal ratios are studied. The results of this article show how this model satisfactorily predicts the performance of PBFB gasifiers.

  15. Conceptual designs of pressurized fluidized bed and pulverized coal fired power plants

    International Nuclear Information System (INIS)

    Doss, H.S.; Bezella, W.A.; Hamm, J.R.; Pietruszkiewicz, J.

    1984-01-01

    This paper presents the major technical and economic characteristics of steam and air-cooled pressurized fluidized bed (PFB) power plant concepts, along with the characteristics of a pulverized coal fired power plant equipped with an adipic acid enhanced wet-limestone flue gas desulfurization system. Conceptual designs for the three plants were prepared to satisfy a set of common groundrules developed for the study. Grassroots plants, located on a generic plant site were assumed. The designs incorporate technologies projected to be commercial in the 1990 time frame. Power outputs, heat rates, and costs are presented

  16. Capture of SO2 by limestone in a 71 MWe pressurized fluidized bed boiler

    Directory of Open Access Journals (Sweden)

    Shimizu Tadaaki

    2003-01-01

    Full Text Available A 71 MWe pressurized fluidized bed coal combustor was operated. A wide variety of coals were burnt under fly ash recycle conditions. Limestone was fed to the combustor as bed material as well as sorbent. The emission of SO^ and limestone attrition rate were measured. A simple mathematical model of SO? capture by limestone with intermittent solid attrition was applied to the analysis of the present experimental results. Except for high sulfur fuel, the results of the present model agreed with the experimental results.

  17. Pressurized fluidized-bed hydroretorting of Eastern oil shales -- Beneficiation

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Lau, F.S.; Mensinger, M.C. (Institute of Gas Technology, Chicago, IL (United States)); Schultz, C.W.; Mehta, R.K.; Lamont, W.E. (Alabama Univ., University, AL (United States)); Chiang, S.H.; Venkatadri, R. (Pittsburgh Univ., PA (United States)); Misra, M. (Nevada Univ., Reno, NV (United States))

    1992-05-01

    The Mineral Resources Institute at the University of Alabama, along with investigators from the University of Pittsburgh and the University of Nevada-Reno, have conducted a research program on the beneficiation, of Eastern oil shales. The objective of the research program was to evaluate and adapt those new and emerging technologies that have the potential to improve the economics of recovering oil from Eastern oil shales. The technologies evaluated in this program can be grouped into three areas: fine grinding kerogen/mineral matter separation, and waste treatment and disposal. Four subtasks were defined in the area of fine grinding. They were as follows: Ultrasonic Grinding, Pressure Cycle Comminution, Stirred Ball Mill Grinding, and Grinding Circuit Optimization. The planned Ultrasonic grinding research was terminated when the company that had contracted to do the research failed. Three technologies for effecting a separation of kerogen from its associated mineral matter were evaluated: column flotation, the air-sparged hydrocyclone, and the LICADO process. Column flotation proved to be the most effective means of making the kerogen/mineral matter separation. No problems are expected in the disposal of oil shale tailings. It is assumed that the tailings will be placed in a sealed pond and the water recycled to the plant as is the normal practice. It may be advantageous, however, to conduct further research on the recovery of metals as by-products and to assess the market for tailings as an ingredient in cement making.

  18. Image analysis of bubble behavior in the pressurized fluidized bed using neutron radiograph

    International Nuclear Information System (INIS)

    Katoh, Yasuo; Miyamoto, Masahide; Miike, Hidetoshi; Kishimoto, Yasuyuki; Matsubayasi, Masahito; Mochiki, Kouichi.

    1996-01-01

    It is very important to know about the formation for bubble production growth and destruction. Because blowing gas nozzle decide the ability of the solid-gas fluidized bed system. For the pressurized 3-D fluidized bed, it was some interested in the bubble production and configuration which was taken place the interaction between bubble and particle under the pressurized condition. For the understanding of the three dimensional characteristics of production bubble under pressurized condition, the study of visualization of neutron radiograph seemed to be useful. In stead of typical X-ray visualization method, visualization of neutron radiograph method for observation of bubble behavior were carried out. Then an image analysis of it was done the same way as two dimension method P-system (PIAS-LA555WS Image Analysis). As the results, the characteristic of production bubble was more clear quantitatively, for example, the bubble production frequency, the bubble diameter and the bubble horizontal and vertical sizes so on. (author)

  19. Waste-gasification efficiency of a two-stage fluidized-bed gasification system.

    Science.gov (United States)

    Liu, Zhen-Shu; Lin, Chiou-Liang; Chang, Tsung-Jen; Weng, Wang-Chang

    2016-02-01

    This study employed a two-stage fluidized-bed gasifier as a gasification reactor and two additives (CaO and activated carbon) as the Stage-II bed material to investigate the effects of the operating temperature (700°C, 800°C, and 900°C) on the syngas composition, total gas yield, and gas-heating value during simulated waste gasification. The results showed that when the operating temperature increased from 700 to 900°C, the molar percentage of H2 in the syngas produced by the two-stage gasification process increased from 19.4 to 29.7mol% and that the total gas yield and gas-heating value also increased. When CaO was used as the additive, the molar percentage of CO2 in the syngas decreased, and the molar percentage of H2 increased. When activated carbon was used, the molar percentage of CH4 in the syngas increased, and the total gas yield and gas-heating value increased. Overall, CaO had better effects on the production of H2, whereas activated carbon clearly enhanced the total gas yield and gas-heating value. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  20. Monitoring the fluidized bed granulation process based on S-statistic analysis of a pressure time series.

    Science.gov (United States)

    Chaplin, Gareth; Pugsley, Todd; Winters, Conrad

    2005-09-30

    Pressure fluctuation measurements collected during the fluidized bed granulation of pharmaceutical granule have been analyzed using the attractor comparison technique denoted as the S-statistic. Divergence of the bed state from the reference during granulation is followed by a return to a condition statistically similar to the original state of the dry fluidized ingredients on drying. This suggests insensitivity of the S-statistic technique to the changes in particle size distribution occurring during the granulation process. Consequently, the monitoring of pressure fluctuations alone may provide an easily implemented technique for the tracking of granule moisture and process end-point determination.

  1. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. (Argonne National Lab., IL (United States)); Banerjee, D.D. (Illinois Clean Coal Inst., Carterville, IL (United States))

    1993-01-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950[degree]C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  2. Measurement of alkali-vapor emission from pressurized fluidized-bed combustion of Illinois coals

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.H.D.; Teats, F.G.; Swift, W.M. [Argonne National Lab., IL (United States); Banerjee, D.D. [Illinois Clean Coal Inst., Carterville, IL (United States)

    1993-04-01

    Two Illinois Herrin No. 6 coals and one Illinois Springfield No. 5 coal were separately combusted in a laboratory-scale (15-cm dia) pressurized fluidized-bed combustor (PFBC) combined with an alkali sorber. These coals were combusted in a fluidized bed of Tymochtee dolomite at temperatures ranging from 910 to 950{degree}C and a system pressure of 9.2 atm absolute. Alkali-vapor emission (Na and K) in the PFBC flue gas was determined by the analytical activated-bauxite sorber bed technique developed at Argonne National Laboratory. The test results showed that sodium is the major alkali-vapor species present in the PFBC flue gas, and that the level of sodium-vapor emission increases linearly with both Na and Cl contents in the coals. This suggests that the sodium-vapor emission results from direct vaporization of NaCl present in the coals. The measured alkali-vapor concentration (Na + K), 67 to 190 ppbW, is more than 2.5 times greater than the allowable alkali limit of 24 ppb for an industrial gas turbine. Combusting these coals in a PFBC for power generation may require developing a method to control alkali vapors.

  3. Performance analysis of RDF gasification in a two stage fluidized bed-plasma process.

    Science.gov (United States)

    Materazzi, M; Lettieri, P; Taylor, R; Chapman, C

    2016-01-01

    The major technical problems faced by stand-alone fluidized bed gasifiers (FBG) for waste-to gas applications are intrinsically related to the composition and physical properties of waste materials, such as RDF. The high quantity of ash and volatile material in RDF can provide a decrease in thermal output, create high ash clinkering, and increase emission of tars and CO2, thus affecting the operability for clean syngas generation at industrial scale. By contrast, a two-stage process which separates primary gasification and selective tar and ash conversion would be inherently more forgiving and stable. This can be achieved with the use of a separate plasma converter, which has been successfully used in conjunction with conventional thermal treatment units, for the ability to 'polish' the producer gas by organic contaminants and collect the inorganic fraction in a molten (and inert) state. This research focused on the performance analysis of a two-stage fluid bed gasification-plasma process to transform solid waste into clean syngas. Thermodynamic assessment using the two-stage equilibrium method was carried out to determine optimum conditions for the gasification of RDF and to understand the limitations and influence of the second stage on the process performance (gas heating value, cold gas efficiency, carbon conversion efficiency), along with other parameters. Comparison with a different thermal refining stage, i.e. thermal cracking (via partial oxidation) was also performed. The analysis is supported by experimental data from a pilot plant. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. On partial fluidization in rotating fluidized beds

    International Nuclear Information System (INIS)

    Kao, J.; Pfeffer, R.; Tardos, G.I.

    1987-01-01

    In a rotating fluidized bed, unlike in a conventional fluidized bed, the granules are fluidized layer by layer from the (inner) free surface outward at increasing radius as the gas velocity is increased. This is a very significant and interesting phenomenon and is extremely important in the design of these fluidized beds. The phenomenon was first suggested in a theoretical analysis and recently verified experimentally in the authors' laboratory. However, in the first paper, the equations presented are too cumbersome and the influence of bed thickness is not clearly stated. In this note the authors present simplified equations, based on that paper, for the pressure drop and the minimum fluidizing velocities in a rotating fluidized bed. Experimental data are also shown and compared with the theoretical model, and the effect of bed thickness is shown. Furthermore, an explanation for the observation of a maximum in the pressure drop vs. velocity curve instead of the plateau derived by Chen is proposed

  5. Application of a novel atmospheric pressure plasma fluidized bed in the powder surface modification

    International Nuclear Information System (INIS)

    Chen Guangliang; Chen Shihua; Zhou Mingyan; Feng Wenran; Gu Weichao; Yang Size

    2006-01-01

    A novel atmospheric pressure plasma fluidized bed (APPFB) with one liquid electrode was designed, and its preliminary discharge characteristics were studied. The glow discharge in the APPFB was generated by applying a low power with helium (He) gas, and the plasma gas temperature was no higher than 320 K when the applied power was lower than 11 W. The plasma optical emission spectrum (OES) of the gas mixture consisting of He and hexamethyldisiloxane (HMDSO) was recorded by a UV-visible monochromator. The calcium carbonate powders were modified by APPFB using HMDSO in the He plasma. The powder surface energy was decreased greatly by coating an organosilicon polymer onto the powder surface. This surface modification process changed the wettability of the powder from super-hydrophilicity to super-hydrophobicity, and the contact angle of water on the modified powders surface was greater than 160 0

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-31

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

  7. Removal of pharmaceuticals and organic matter from municipal wastewater using two-stage anaerobic fluidized membrane bioreactor.

    Science.gov (United States)

    Dutta, Kasturi; Lee, Ming-Yi; Lai, Webber Wei-Po; Lee, Chien Hsien; Lin, Angela Yu-Chen; Lin, Cheng-Fang; Lin, Jih-Gaw

    2014-08-01

    The aim of present study was to treat municipal wastewater in two-stage anaerobic fluidized membrane bioreactor (AFMBR) (anaerobic fluidized bed reactor (AFBR) followed by AFMBR) using granular activated carbon (GAC) as carrier medium in both stages. Approximately 95% COD removal efficiency could be obtained when the two-stage AFMBR was operated at total HRT of 5h (2h for AFBR and 3h for AFMBR) and influent COD concentration of 250mg/L. About 67% COD and 99% TSS removal efficiency could be achieved by the system treating the effluent from primary clarifier of municipal wastewater treatment plant, at HRT of 1.28h and OLR of 5.65kg COD/m(3)d. The system could also effectively remove twenty detected pharmaceuticals in raw wastewaters with removal efficiency in the range of 86-100% except for diclofenac (78%). No other membrane fouling control was required except scouring effect of GAC for flux of 16LMH. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Pressurized fluidized-bed hydroretorting of eastern oil shales. Progress report, September 1992--November 1992

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Mensinger, M.C.; Rue, D.M.; Lau, F.S.

    1992-12-01

    This report presents the work performed during the program quarter from September 1, 1992 though November 30, 1992. The Institute of Gas Technology (IGT) is the prime contractor for the program extension to develop the Pressurized Fluidized-Bed Hydroretorting II system technology. Four institutions are working with IGT as subcontractors. Task achievements are discussed for the following active tasks of the program: Subtask 3.7 innovative reactor concept testing; Subtask 3.9 catalytic hydroretorting; Subtask 3.10 autocatalysis in hydroretorting; Subtask 3.11 shale oil upgrading and evaluation; Subtask 4.1.3 stirred ball mill grinding; Subtask 4.1.5 alternative technology evaluation; Subtask 4.1.6 ultrafine size separation; Subtask 4.2.1 column flotation tests; Subtask 4.4 integrated grinding and flotation; Subtask 4.7 economic analysis; Subtask 6.2.2 wastewater treatability; Subtask 6.2.3 waste management facility conceptual design; and Subtask 8 project management and reporting.

  9. Pressurized Fluidized-Bed Hydroretorting of eastern oil shales. Final report, June 1992--January 1993

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Mensinger, M.C.; Erekson, E.J.; Rue, D.M.; Lau, F.S. [Institute of Gas Technology, Chicago, IL (United States); Schultz, C.W.; Hatcher, W.E. [Alabama Univ., University, AL (United States). Mineral Resources Inst.; Parekh, B.K. [Kentucky Univ., Lexington, KY (United States). Center for Applied Energy Research; Bonner, W.P. [Tennessee Technological Univ., Cookeville, TN (United States)

    1993-03-01

    The Devonian oil shales of the Eastern United States are a significant domestic energy resource. The overall objective of the multi-year program, initiated in September 1987 by the US Department of Energy was to perform the research necessary to develop the pressurized fluidized-bed hydroretorting (PFH) process for producing oil from Eastern oil shales. The program also incorporates research on technologies in areas such as raw shale preparation, beneficiation, product separation and upgrading, and waste disposal that have the potential of improving the economics and/or environmental acceptability of recovering oil from oil shales using the PFH process. The program was divided into the following active tasks: Task 3 -- Testing of Process Improvement Concepts; Task 4 -- Beneficiation Research; Task 6 -- Environmental Data and Mitigation Analyses; and Task 9 -- Information Required for the National Environmental Policy Act. In order to accomplish all of the program objectives, tho Institute of Gas Technology (ICT), the prime contractor, worked with four other institutions: The University of Alabama/Mineral Resources Institute (MRI), the University of Alabama College of Engineering (UA), University of Kentucky Center for Applied Energy Research (UK-CAER), and Tennessee Technological University (TTU). This report presents the work performed by IGT from June 1, 1992 through January 31, 1993.

  10. Assessment of pressurized fluidized-bed combustion power plants using high sulfur coal

    International Nuclear Information System (INIS)

    Wheeldon, J.M.; Drenker, S.G.; Booras, G.S.; McKinsey, R.R.

    1993-01-01

    Results of an EPRI engineering and economic study confirm that pressurized fluidized bed combustion (PFBC) power plants have lower capital costs than other advanced fossil technologies. The operating costs are shown to be sensitive to coal properties, particularly the sulfur content. Lower sulfur content coals result in lower sorbent and ash disposal costs and a correspondingly lower cost of electricity. These sensitivity studies indicate that for medium to low sulfur coals the levelized cost of electricity from PFBC power plants is lower than from integrated gasification combined cycle (IGCC) plants. Even though a low sulfur coal potentially offers the lowest cost of electricity, if it has to be transported any distance it may be more economic to use a local high sulfur coal. To test this hypothesis, costing were carried out for a utility-scale bubbling PFBC power plant located somewhere in the USA. The cost of electricity was determined for a local high sulfur bituminous coal and three low sulfur coals, two Appalachian bituminous coal, and a Wyoming subbituminous coal. The resulting costs of electricity were very similar. The closer the plant is the low sulfur coal producing regions the less economically attractive will be the high sulfur coal. Means of making the high sulfur coal more competitive are discussed. 18 refs., 3 figs., 8 tabs

  11. Pressurized fluidized-bed combustion part-load behavior. Volume I. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, A. G.; Pillai, K. K.; Raven, P.; Wood, P.

    1981-09-01

    Tests performed during 1980 to determine the part-load characteristics of a pressurized fluidized-bed combustor for a combined-cycle power plant and to examine its behavior during load changing are discussed. Part-load operation was achieved by varying the bed temperature by amounts between 200 to 300/sup 0/F and the bed depth from between 9 and 10 ft at rates varying between 0.2 ft/min and 0.5 ft/min. The performance at part-load steady-state conditions and during transient conditions is reported with information on combustion efficiency (99% at full-load with 9 ft bed depth and 1650/sup 0/F bed temperature; 95% with 4 ft depth and 1390/sup 0/F); sulfur retention (95/sup 0/ at full load to 80% at low bed depth and low bed temperature); sulfur emissions (no definitive results); NO/sub x/ emissions (tendency for increase as bed temperature was reduced); alkali emissions (no bed temperature effect detected); and heat transfer. It was demonstrated that load can be altered in a rapid and controlled manner by changing combinations of bed depth temperature and pressure. The most important practical change was the reduction in O/sub 2/ concentration which occurred when the bed height was increased at a rapid rate. The extra energy required to reheat the incoming bed material resulted (in the most extreme case) in a temporary drop in excess air from 65% to 12%. In a full-scale plant the loss of heat from the stored bed material would be much lower and the excess air trough when increasing load would not be as pronounced. Nevertheless, it seems prudent to design full-scale plant for a full load excess air of not less than about 50% when using bed depth as a load control parameter.

  12. Pressurized fluidized-bed hydroretorting of Eastern oil shales. Annual report, June 1991--May 1992

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Mensinger, M.C.; Rue, D.M.; Lau, F.S. [Institute of Gas Technology, Chicago, IL (United States); Schultz, C.W. [Alabama Univ., University, AL (United States); Parekh, B.K. [Kentucky Univ., Lexington, KY (United States); Misra, M. [Nevada Univ., Reno, NV (United States); Bonner, W.P. [Tennessee Technological Univ., Cookeville, TN (United States)

    1992-11-01

    The Devonian oil shales of the Eastern United States are a significant domestic energy resource. The overall objective of the multi-year program, initiated in October 1987 by the US Department of Energy is to perform the research necessary to develop the Pressurized Fluidized-Bed Hydroretorting (PFH) process for producing oil from Eastern oil shales. The program also incorporates research on technologies in areas such as raw shale preparation, beneficiation, product separation, and waste disposal that have the potential of improving the economics and/or environmental acceptability of recovering oil from oil shales using the PFH process. The results of the original 3-year program, which was concluded in May 1991, have been summarized in a four-volume final report published by IGT. DOE subsequently approved a 1-year extension to the program to further develop the PFH process specifically for application to beneficiated shale as feedstock. Studies have shown that beneficiated shale is the preferred feedstock for pressurized hydroretorting. The program extension is divided into the following active tasks. Task 3. testing of process improvement concepts; Task 4. beneficiation research; Task 5. operation of PFH on beneficiated shale; Task 6. environmental data and mitigation analyses; Task 7. sample procurement, preparation, and characterization; and Task 8. project management and reporting. In order to accomplish all the program objectives, the Institute of Gas Technology (IGT), the prime contractor, worked with four other institutions: the University of Alabama/Mineral Resources Institute (MRI), the University of Kentucky Center for Applied Energy Research (UK-CAER), the University of Nevada (UN) at Reno, and Tennessee Technological University (TTU). This report presents the work performed during the program extension from June 1, 1991 through May 31, 1992.

  13. Studies on nitrogen oxides (NO{sub x} and N{sub 2}O) in pressurized fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yong

    1998-09-01

    This thesis describes the experimental studies of nitrogen oxide (NO, NO{sub 2}, N{sub 2}O) emissions in pressurized fluidized bed combustion (PFBC). In the first part of the thesis the background and the objectives of this study are introduced. The second part summarizes the fundamental knowledge about the formation and destruction of nitrogen oxides in coal combustion, particularly in the conditions of PFBC. The instrumentation of test facilities, measurement and data analysis is described in the third part. Then the most important experimental results follow in the next parts. The forth part describes the results from a PFBC test rig and an empirical modelling for predicting the emissions of NO{sub x} and N{sub 2}O. Finally, the fundamental work on coal combustion and fuel nitrogen conversion in a PFBC batch reactor is presented. These studies clearly confirm the potential of PFBC technology in the control nitrogen of oxide emissions. The research in the test rig was concentrated on determining the effects of process parameters on the emissions of nitrogen oxides with different fuels. Another objective was to examine the reduction of nitrogen oxides with the control methods in PFBC conditions, including ammonia injection and air staging combustion for reducing NO, and high temperature operations for reducing N{sub 2}0. The results indicate that pressurized operation suppresses the conversion of fuel-N to nitrogen oxides and favors with employing the reduction methods for further nitrogen oxide reduction, for instance the temperature window of NO reduction with ammonia injection has been found to be widened to even lower temperature range. Maximum reductions of 80-85 % with ammonia injection and 75-80 % with air staging combustion were achieved in the conditions examined. Considerably low emissions of N{sub 2}O (<7 ppm) were obtained in the tests of N{sub 2}O control, and thermal decomposition proved to be the laming pathway of N{sub 2}O destruction in PFBC. In

  14. Utilization of desulfurization gypsum to producing SO{sub 2} and CaO in multi-stage fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Zhu; Wang, Tao; Yang, Hairui; Zhang, Hai; Zhang, Zuyi [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering

    2013-07-01

    With emission control becomes more and more stringent, flue gas desulphurization (FGD) is commonly employed for desulfurization. However, the product of FGD, gypsum, causes the unexpected environmental problems. How to utilize the byproduct of FGD effectively and economically is a challenging task. This paper proposed the new technical process to produce SO{sub 2} and CaO by reducing the gypsum in multi-stage fluidized bed reactor with different atmosphere. In addition, some preliminary experiments were carried out in PTGA. The results show that CO concentration has little effect on the initial decomposing temperature, but affect the decomposing rate of phosphogypsum obviously. The decomposing product composed of CaS and CaO simultaneously. The ratio of the two products was determined by CO concentration. Lower CO content benefits to produce more CO product and more SO{sub 2}. The decomposition reaction of phosphogypsum in reducing atmosphere is parallel competition reaction. Therefore, it is necessary to eliminate the effect of CaS and other byproduct efficiently by the new technology, which utilize multi-atmosphere in multistage fluidized bed reactors.

  15. Identification of defluidization region in a gas-solid fluidized bed using a method based on pressure fluctuation measurements

    Directory of Open Access Journals (Sweden)

    M. R. Parise

    2009-09-01

    Full Text Available Industrial applications that involve fluidized bed operations must prevent the undesirable phenomenon of partial or complete bed defluidization. Defluidization can be avoided by increasing the gas velocity and/or, in some cases, changing the solid feed conditions in the system, provided that the changes in the hydrodynamics of the flow are detected early enough. The use of a technique that can perform an early detection of the defluidization condition in industrial applications is important, in order to avoid the loss of efficiency or even an undesirable shutting down of the process. The objective of this work is to show the application of a method for early detection of the condition where the bed is tending to the defluidization, in a gas-solid fluidized bed flow. The method is based on pressure fluctuation measurements. Experimental tests are carried out using two solid particles: microcrystalline cellulose and sand. Results show that the proposed method is efficient in detecting the fluidization condition in a conventional bubbling bed regime. The potential of application of the technique is also shown for the control of the defluidization phenomenon in industry.

  16. CO-PRODUCTION OF HYDROGEN AND ELECTRICITY USING PRESSURIZED CIRCULATING FLUIDIZED BED GASIFICATION TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Zhen Fan

    2006-05-30

    Foster Wheeler has completed work under a U.S. Department of Energy cooperative agreement to develop a gasification equipment module that can serve as a building block for a variety of advanced, coal-fueled plants. When linked with other equipment blocks also under development, studies have shown that Foster Wheeler's gasification module can enable an electric generating plant to operate with an efficiency exceeding 60 percent (coal higher heating value basis) while producing near zero emissions of traditional stack gas pollutants. The heart of the equipment module is a pressurized circulating fluidized bed (PCFB) that is used to gasify the coal; it can operate with either air or oxygen and produces a coal-derived syngas without the formation of corrosive slag or sticky ash that can reduce plant availabilities. Rather than fuel a gas turbine for combined cycle power generation, the syngas can alternatively be processed to produce clean fuels and or chemicals. As a result, the study described herein was conducted to determine the performance and economics of using the syngas to produce hydrogen for sale to a nearby refinery in a hydrogen-electricity co-production plant setting. The plant is fueled with Pittsburgh No. 8 coal, produces 99.95 percent pure hydrogen at a rate of 260 tons per day and generates 255 MWe of power for sale. Based on an electricity sell price of $45/MWhr, the hydrogen has a 10-year levelized production cost of $6.75 per million Btu; this price is competitive with hydrogen produced by steam methane reforming at a natural gas price of $4/MMBtu. Hence, coal-fueled, PCFB gasifier-based plants appear to be a viable means for either high efficiency power generation or co-production of hydrogen and electricity. This report describes the PCFB gasifier-based plant, presents its performance and economics, and compares it to other coal-based and natural gas based hydrogen production technologies.

  17. Post-treatment of secondary wastewater treatment plant effluent using a two-stage fluidized bed bioreactor system.

    Science.gov (United States)

    Safari, Golam Hossein; Yetilmezsoy, Kaan; Mahvi, Amir Hossein; Zarrabi, Mansur

    2013-06-17

    The aim of this study was to investigate the performance of a two-stage fluidized bed reactor (FBR) system for the post-treatment of secondary wastewater treatment plant effluents (Shahrak Gharb, Tehran, Iran). The proposed treatment scheme was evaluated using pilot-scale reactors (106-L of capacity) filled with PVC as the fluidized bed (first stage) and gravel for the filtration purpose (second stage). Aluminum sulfate (30 mg/L) and chlorine (1 mg/L) were used for the coagulation and disinfection of the effluent, respectively. To monitor the performance of the FBR system, variation of several parameters (biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total phosphorous, total coliform and fecal coliform) were monitored in the effluent wastewater samples. The results showed that the proposed system could effectively reduce BOD5 and COD below 1.95 and 4.06 mg/L, respectively. Turbidity of the effluent could be achieved below 0.75 NTU, which was lower than those reported for the disinfection purpose. The total phosphorus was reduced to 0.52 mg/L, which was near the present phosphorous standard for the prevention of eutrophication process. Depending on both microorganism concentration and applied surface loading rates (5-10 m/h), about 35 to 75% and 67 to 97% of coliform were removed without and with the chlorine addition, respectively. Findings of this study clearly confirmed the efficiency of the FBR system for the post-treatment of the secondary wastewater treatment plant effluents without any solid problem during the chlorination.

  18. Post-Treatment of Secondary Wastewater Treatment Plant Effluent Using A Two-Stage Fluidized Bed Bioreactor System

    Directory of Open Access Journals (Sweden)

    Golam Hossein Safari

    2013-06-01

    Full Text Available The aim of this study was to investigate the performance of a two-stage fluidized bed reactor (FBR system for the post-treatment of secondary wastewater treatment plant effluents (Shahrak Gharb, Tehran, Iran. The proposed treatment scheme was evaluated using pilot-scale reactors (106-L of capacity filled with PVC as the fluidized bed (first stage and gravel for the filtration purpose (second stage. Aluminum sulfate (30 mg/L and chlorine (1 mg/L were used for the coagulation and disinfection of the effluent, respectively. To monitor the performance of the FBR system, variation of several parameters (biochemical oxygen demand (BOD5, chemical oxygen demand (COD, turbidity, total phosphorous, total coliform and fecal coliform were monitored in the effluent wastewater samples. The results showed that the proposed system could effectively reduce BOD5 and COD below 1.95 and 4.06 mg/L, respectively. Turbidity of the effluent could be achieved below 0.75 NTU, which was lower than those reported for the disinfection purpose. The total phosphorus was reduced to 0.52 mg/L, which was near the present phosphorous standard for the prevention of eutrophication process. Depending on both microorganism concentration and applied surface loading rates (5–10 m/h, about 35 to 75% and 67 to 97% of coliform were removed without and with the chlorine addition, respectively. Findings of this study clearly confirmed the efficiency of the FBR system for the post-treatment of the secondary wastewater treatment plant effluents without any solid problem during the chlorination.

  19. Development of a low-temperature two-stage fluidized bed incinerator for controlling heavy-metal emission in flue gases

    International Nuclear Information System (INIS)

    Peng, Tzu-Huan; Lin, Chiou-Liang; Wey, Ming-Yen

    2014-01-01

    This study develops a low-temperature two-stage fluidized bed system for treating municipal solid waste. This new system can decrease the emission of heavy metals, has low construction costs, and can save energy owing to its lower operating temperature. To confirm the treatment efficiency of this system, the combustion efficiency and heavy-metal emission were determined. An artificial waste containing heavy metals (chromium, lead, and cadmium) was used in this study. The tested parameters included first-stage temperature and system gas velocity. Results obtained using a thermogravimetric analyzer with a differential scanning calorimeter indicated that the first-stage temperature should be controlled to at least 400 °C. Although, a large amount of carbon monoxide was emitted after the first stage, it was efficiently consumed in the second. Loss of the ignition values of ash residues were between 0.005% and 0.166%, and they exhibited a negative correlation with temperature and gas velocity. Furthermore, the emission concentration of heavy metals in the two-stage system was lower than that of the traditional one-stage fluidized bed system. The heavy-metal emissions can be decreased by between 16% and 82% using the low-temperature operating process, silica sand adsorption, and the filtration of the secondary stage. -- Graphical abstract: Heavy-metal emission concentrations in flue gases under different temperatures and gas velocities (dashed line: average of the heavy-metal emission in flue gases in the one-stage fluidized-bed incinerator). Highlights: • Low temperature two-stage system is developed to control heavy metal. • The different first-stage temperatures affect the combustion efficiency. • Surplus CO was destroyed efficiently by the secondary fluidized bed combustor. • Metal emission in two-stage system is lower than in the traditional system. • Temperature, bed adsorption, and filtration are the main control mechanisms

  20. Sodium and steam leak simulation studies for fluidized bed steam generators

    International Nuclear Information System (INIS)

    Keeton, A.R.; Vaux, W.G.; Lee, P.K.; Witkowski, R.E.

    1976-01-01

    An experimental program is described which was conducted to study the effects of sodium or steam leaking into an operating fluidized bed of metal or ceramic particles at 680 to 800 0 K. This effort was part of the early development studies for a fluidized-bed steam generator concept using helium as the fluidizing gas. Test results indicated that steam and small sodium leaks had no effect on the quality of fluidization, heat transfer coefficient, temperature distribution, or fluidizing gas pressure drop across the bed. Large sodium leaks, however, immediately upset the operation of the fluidized bed. Both steam and sodium leaks were detected positively and rapidly at an early stage of a leak by instruments specifically selected to accomplish this

  1. Hydrodynamic analysis of a three-fluidized bed reactor cold flow model for chemical looping hydrogen generation. Pressure characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhipeng; Xiang, Wenguo; Chen, Shiyi; Wang, Dong [Southeast Univ., Nanjing (China). School of Energy and Environment

    2013-07-01

    Chemical looping hydrogen generation (CLHG) can produce pure hydrogen with inherent separation of CO{sub 2} from fossils fuel. The process involves a metal oxide, as an oxygen carrier, such as iron oxide. The CLHG system consists of three reactors: a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). In the FR, the fuel gases react with iron oxides (hematite Fe{sub 2}O{sub 3}, magnetite Fe{sub 3}O{sub 4}, wuestite FeO), generating reduced iron oxides (FeO or even Fe), and with full conversion of gaseous fuels, pure CO{sub 2} can be obtained after cooling the flue gas from the fuel reactor; in the SR, FeO and Fe reacts with steam to generate magnetite (Fe{sub 3}O{sub 4}) and H{sub 2}, the latter representing the final target product of the process; in the AR, the magnetite is oxidized back to hematite which is used in another cycle. A cold flow model of three-fluidized bed for CLHG corresponding to 50 KW hot units has been built. A major novelty of this facility is the compact fuel reactor, which integrates a bubble and a fast fluidized bed to avoid the incomplete conversion of the fuel gas caused by the thermodynamics equilibrium. In order to study the pressure characteristics and the solids concentration of the system, especially in the fuel reactor, the gas velocity of three reactors, gas flow of L-type value, total solids inventory (TSI) and the secondary air of fuel reactor were varied. Results show that the pressure and the solids concentration are strongly influenced by the fluidizing-gas velocity of three reactors. Moreover, the entrainment of the upper part of fuel reactor increases as the total solids inventory increases, and the operating range of the FR can be changed by introducing secondary air or increasing the total solids inventory.

  2. Biomass oxygen/steam gasification in a pressurized bubbling fluidized bed: Agglomeration behavior

    International Nuclear Information System (INIS)

    Zhou, Chunguang; Rosén, Christer; Engvall, Klas

    2016-01-01

    Highlights: • Dolomite is a superior material in preventing bed agglomeration. • Small molten ash particles deposited on magnesite at bed temperatures above 1000 °C. • The performance, when using magnesite, is sensitive to temperature disturbances. • The anti-agglomeration mechanisms of Ca- and Mg-bearing materials were discussed. - Abstract: In this study, the anti-agglomeration abilities of Ca- and Mg-containing bed materials, including dolomite and magnesite, in a pressurized bubbling fluidized bed gasifier using pine pellets and birch chips as feedstock, is investigated. The most typical bed material—silica sand—was also included as a reference for comparison. The sustainability of the operation was evaluated via analyzing the temperatures at different levels along the bed height. During the performances, the aim was to keep the temperature at the bottom zone of the reactor at around 870 °C. However, the success highly depends on the bed materials used in the bed and the temperature can vary significantly in case of agglomeration or bad mixing of bed materials and char particles. Both Glanshammar and Sala dolomites performed well with no observed agglomeration tendencies. In case of magnesite, the bed exhibited a high agglomeration tendency. Silica sand displayed the most severe agglomeration among all bed materials, even when birch chips with a low silica content was fed at a relatively low temperature. The solid samples of all the bed materials were inspected by light microscopy and Scanning Electron Microscopy (SEM). The Energy Dispersive Spectroscopy (EDS) detector was used to detect the elemental distribution in the surface. The crystal chemical structure was analyzed using X-ray Diffraction (XRD). Magnesite agglomerates glued together by big molten ash particles. There was no coating layer detected on magnesite particles at bed temperatures – below 870 °C. But when the temperature was above 1000 °C, a significant amount of small molten

  3. Advanced air staging techniques to improve fuel flexibility, reliability and emissions in fluidized bed co-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Aamand, Lars-Erik; Leckner, Bo [Chalmers Technical Univ., Goeteborg (Sweden); Luecke, Karsten; Werther, Joachim [Technical Univ. of Hamburg-Harburg (Germany)

    2001-12-01

    A joint research project between the Technical University of Hamburg-Harburg and Chalmers Technical University. For operation under co-combustion the following results should be considered: The high ash content of the sewage sludge results in significantly increased ash flows. Although high alkali metal concentrations are found in the sewage sludge ash, no critical concentrations were reached and tendencies to fouling were not observed. The trace metal input rises with increased sludge fraction. However, emissions of metal compounds were well below legal limits. The trace metals tend to accumulate on the fly ash. In general, very low fuel nitrogen conversions to NO and N{sub 2}O of 2 - 4 % are achievable. With coal as a base fuel alternative air staging with secondary air supply after solids separation attains even lower NO emissions than normal staging without strongly affecting CO and SO{sub 2} emissions. Alternative staging also reduces N{sub 2}O emissions. An optimum for the excess air ratio in the riser of 1.05 was found for a total excess air ratio of 1.2. The higher the volatile content of the fuel is, the less effective the NO reduction due to air staging becomes. The measurements suggest that the optimum gas residence time regarding the emissions in CFB combustors is around 6 to 7 s. These times are achieved in commercial scale plants due to their large cyclones that perhaps partly can replace a large afterburner chamber. The circulating fluidized bed boiler can be operated in a very flexible way with various fuel mixtures up to an energy fraction of sludge of 25% without exceeding legal emission limits.

  4. Development program on pressurized fluidized-bed combustion. Annual report, July 1975--June 1976

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, G.J.; Johnson, I.; Cunningham, P.T.

    1976-07-01

    The feasibility of using fluidized-bed combustors in power and steam plants is being evaluated. The concept involves burning fuels such as coal in a fluidized bed of either a limestone (CaCO/sub 3/) or a synthetically prepared calcium-containing stone. The calcium reacts with the sulfur to form CaSO/sub 4/, which remains in the bed, thus decreasing the level of SO/sub 2/ in the flue gas. Levels of NO/sub x/ in the flue gas are low. In a separate step, the CaSO/sub 4/ is regenerated to CaO by reductive decomposition at Ca/sub solar/ 1100/sup 0/C for reuse in the combustor. Progress is reported on the following: the effect of regeneration operating variables on extent of regeneration and SO/sub 2/ concentration in the off-gas using coal as the source of reducing agent and of heat; the alternate combustion and regeneration behavior of stone; the rate and extent of sulfation of agents impregnated on Al/sub 2/O/sub 3/; the effect of variables on sorption and release of sulfur for CaO-impregnated stone; attrition resistance of stone; the kinetic and structural changes occurring during half-calcination of dolomite; the CaS-CaSO/sub 4/ regeneration reaction; and the volatility of trace elements when heating coal ash. Procurement and disposal of regenerated stone, minimum fluidization studies, modeling of a gas-solid combustion reaction and of the regeneration process, combustion studies using different sizes of coal and additive and also using lignite are reported.

  5. THE SCALE-UP OF LARGE PRESSURIZED FLUIDIZED BEDS FOR ADVANCED COAL-FIRED POWER PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Leon R. Glicksman; Michael Louge; Hesham F. Younis; Richard Tan; Mathew Hyre; Mark Torpey

    2003-11-24

    This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor an agency thereof, nor any of the their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, A combined-cycle High Performance Power System (HIPPS) capable of overall cycle efficiencies approaching 50% has been proposed and designed by Foster Wheeler Development Corporation (FWDC). A pyrolyzer in the first stage of the HIPPS process converts a coal feedstock into fuel gas and char at an elevated pressure of 1.4 Map. (206 psia) and elevated temperature of 930 C (1700 F). The generated char serves as the feedstock for a Pulverized Coal (PC) boiler operating at atmospheric pressure, and the fuel gas is directly fired in a gas turbine. The hydrodynamic behavior of the pyrolyzer strongly influences the quality of both the fuel gas and the generated char, the energy split between the gas turbine and the steam turbine, and hence the overall efficiency of the system. By utilizing a simplified set of scaling parameters (Glicksman et al.,1993), a 4/7th labscale cold model of the pyrolyzer operating at ambient temperature and pressure was constructed and tested. The scaling parameters matched include solid to gas density ratio, Froude number, length to diameter ratio; dimensionless superficial gas velocity and solid recycle rate, particle sphericity and particle size distribution (PSD).

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    1987-07-31

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

  7. Environmental data from laboratory- and bench-scale Pressurized Fluidized-Bed Hydroretorting of Eastern oil shale

    Energy Technology Data Exchange (ETDEWEB)

    Mensinger, M.C.; Rue, D.M.; Roberts, M.J.

    1991-01-01

    As part of a 3-year program to develop the Pressurized Fluidized-Bed Hydroretorting (PFH) Process for Eastern oil shales, IGT conducted tests in laboratory-scale batch and continuous units as well as a 45-kg/h bench-scale unit to generate a data base for 6 Eastern shales. Data were collected during PFH processing of raw Alabama and Indiana shales and a beneficiated Indiana shale for environmental mitigation analyses. The data generated include trace element analyses of the raw feeds and spent shales, product oils, and sour waters. The sulfur compounds present in the product gas and trace components in the sour water were also determined. In addition, the leaching characteristics of the feed and residue solids were determined. The data obtained were used to evaluate the environmental impact of a shale processing plant based on the PFH process. This paper presents the environmental data obtained from bench-scale tests conducted during the program.

  8. Environmental data from laboratory- and bench-scale Pressurized Fluidized-Bed Hydroretorting of Eastern oil shale

    Energy Technology Data Exchange (ETDEWEB)

    Mensinger, M.C.; Rue, D.M.; Roberts, M.J.

    1991-12-31

    As part of a 3-year program to develop the Pressurized Fluidized-Bed Hydroretorting (PFH) Process for Eastern oil shales, IGT conducted tests in laboratory-scale batch and continuous units as well as a 45-kg/h bench-scale unit to generate a data base for 6 Eastern shales. Data were collected during PFH processing of raw Alabama and Indiana shales and a beneficiated Indiana shale for environmental mitigation analyses. The data generated include trace element analyses of the raw feeds and spent shales, product oils, and sour waters. The sulfur compounds present in the product gas and trace components in the sour water were also determined. In addition, the leaching characteristics of the feed and residue solids were determined. The data obtained were used to evaluate the environmental impact of a shale processing plant based on the PFH process. This paper presents the environmental data obtained from bench-scale tests conducted during the program.

  9. Thermal treatment of soil co-contaminated with lube oil and heavy metals in a low-temperature two-stage fluidized bed incinerator

    International Nuclear Information System (INIS)

    Samaksaman, Ukrit; Peng, Tzu-Huan; Kuo, Jia-Hong; Lu, Chien-Hsing; Wey, Ming-Yen

    2016-01-01

    Highlights: • Low-temperature two-stage fluidized bed incineration was applied for soil remediation. • Co-firing of polyethylene with co-contaminated soil was studied. • Co-firing of polyethylene in soil remediation can promote residue quality. • The leachability of heavy metals passed the regulatory threshold values. - Abstract: This study presents the application of a low-temperature two-stage fluidized bed incinerator to remediate contaminants in the soil. The system was designed to control emissions of both gaseous pollutants and heavy metals during combustion. Soil co-contaminated with lube oil and heavy metals such as cadmium, chromium, copper, and lead was examined. Experiments were conducted by estimating various parameters such as operating temperature in the first-stage reactor (500–700 °C), ratio of sand bed height/diameter in the second-stage reactor (H/D: 3, 4, 6), and gas velocity (0.21–0.29 m/s). Heavy metal and gaseous pollutant emissions were also investigated during contaminated soil co-firing with polyethylene. The experimental results indicated that the destruction and removal efficiency of lube oil in treated soil products ranged from 98.27 to 99.93%. On the other hand, leaching tests of bottom ashes illustrated that heavy metals such as chromium, copper, and lead in leachates were complied with the regulations. For gaseous emissions, carbon monoxide concentrations decreased apparently with increasing ratio of sand bed height/diameter in the second-stage reactor. The increase of gas velocity had significant potential to generate the lowest carbon monoxide and particulate matter emissions. Nevertheless, during co-firing with polyethylene, emissions of organic pollutants such as benzene, toluene, ethylbenzene, and xylene and polycyclic aromatic hydrocarbons decrease by using the low-temperature two-stage fluidized bed incineration system.

  10. Heat and mass transfer enforcement of vibrating fluidized bed

    Science.gov (United States)

    Chu, Zhide; Yang, Junhong; Li, Xuhui; Song, Yang

    1994-12-01

    This paper briefly introduces the development of vibrating fluidized bed at home and abroad, elaborates the vibration properties of vibrating fluidized bed, the fluidizing velocity and pressure drop of the bed layer. It also deduces the non-steady state drying dynamic equations of vibrating fluidized bed, analyzes main factors which influence the drying rate and inquires into drying rules of fixed bed and vibrating fluidized bed.

  11. Pressurized fluidized-bed hydroretorting of eastern oil shales. [Estimation of the cost of beneficiating Alabama shale

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Mensinger, M.C.; Rue, D.M.; Lau, F.S.

    1992-12-01

    This report presents the work performed during the program quarter from September 1, 1992 though November 30, 1992. The Institute of Gas Technology (IGT) is the prime contractor for the program extension to develop the Pressurized Fluidized-Bed Hydroretorting II system technology. Four institutions are working with IGT as subcontractors. Task achievements are discussed for the following active tasks of the program: Subtask 3.7 innovative reactor concept testing; Subtask 3.9 catalytic hydroretorting; Subtask 3.10 autocatalysis in hydroretorting; Subtask 3.11 shale oil upgrading and evaluation; Subtask 4.1.3 stirred ball mill grinding; Subtask 4.1.5 alternative technology evaluation; Subtask 4.1.6 ultrafine size separation; Subtask 4.2.1 column flotation tests; Subtask 4.4 integrated grinding and flotation; Subtask 4.7 economic analysis; Subtask 6.2.2 wastewater treatability; Subtask 6.2.3 waste management facility conceptual design; and Subtask 8 project management and reporting.

  12. Co-firing a pressurized fluidized-bed combustion system with coal and refuse derived fuels and/or sludges. Task 16

    Energy Technology Data Exchange (ETDEWEB)

    DeLallo, M.; Zaharchuk, R.

    1994-01-01

    The co-firing of waste materials with coal in utility scale power plants has emerged as an effective approach to produce energy and manage municipal waste. Leading this approach, the atmospheric fluidized-bed combustor (AFBC) has demonstrated its commercial acceptance in the utility market as a reliable source of power burning a variety of waste and alternative fuels. The fluidized bed, with its stability of combustion, reduces the amount of thermochemical transients and provides for easier process control. The application of pressurized fluidized-bed combustor (PFBC) technology, although relatively new, can provide significant enhancements to the efficient production of electricity while maintaining the waste management benefits of AFBC. A study was undertaken to investigate the technical and economic feasibility of co-firing a PFBC with coal and municipal and industrial wastes. Focus was placed on the production of electricity and the efficient disposal of wastes for application in central power station and distributed locations. Wastes considered for co-firing include municipal solid waste (MSW), tire-derived fuel (TDF), sewage sludge, and industrial de-inking sludge. Issues concerning waste material preparation and feed, PFBC operation, plant emissions, and regulations are addressed. This paper describes the results of this investigation, presents conclusions on the key issues, and provides recommendations for further evaluation.

  13. DEVELOPMENT OF PRESSURIZED CIRCULATIONG FLUIDIZED BED PARTIAL GASIFICATION MODULE(PGM)

    Energy Technology Data Exchange (ETDEWEB)

    Archie Robertson

    2003-04-17

    Foster Wheeler Power Group, Inc. is working under US Department of Energy contract No. DE-FC26-00NT40972 to develop a partial gasification module (PGM) that represents a critical element of several potential coal-fired Vision 21 plants. When utilized for electrical power generation, these plants will operate with efficiencies greater than 60% and produce near zero emissions of traditional stack gas pollutants. The new process partially gasifies coal at elevated pressure producing a coal-derived syngas and a char residue. The syngas can be used to fuel the most advanced power producing equipment such as solid oxide fuel cells or gas turbines, or processed to produce clean liquid fuels or chemicals for industrial users. The char residue is not wasted; it can also be used to generate electricity by fueling boilers that drive the most advanced ultra-supercritical pressure steam turbines. The amount of syngas and char produced by the PGM can be tailored to fit the production objectives of the overall plant, i.e., power generation, clean liquid fuel production, chemicals production, etc. Hence, PGM is a robust building block that offers all the advantages of coal gasification but in a more user-friendly form; it is also fuel flexible in that it can use alternative fuels such as biomass, sewerage sludge, etc. This report describes the work performed during the January 1--March 31, 2003 time period.

  14. Fluidization of spherocylindrical particles

    Directory of Open Access Journals (Sweden)

    Mahajan Vinay V.

    2017-01-01

    Full Text Available Multiphase (gas-solid flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD and discrete element method (DEM approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

  15. Fluidization of spherocylindrical particles

    Science.gov (United States)

    Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

    2017-06-01

    Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

  16. Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases.

    Science.gov (United States)

    Mohanty, C R; Meikap, B C

    2011-03-15

    A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO(2)) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO(2) was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO(2) was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO(2) concentration. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Modeling the operation of a three-stage fluidized bed reactor for removing CO2 from flue gases

    International Nuclear Information System (INIS)

    Mohanty, C.R.; Meikap, B.C.

    2011-01-01

    A bubbling counter-current multistage fluidized bed reactor for the sorption of carbon dioxide (CO 2 ) by hydrated lime particles was simulated employing a two-phase model, with the bubble phase assumed to be in plug flow, and the emulsion phase in plug flow and perfectly mixed flow conditions. To meet prescribed permissible limit to emit carbon dioxide from industrial flue gases, dry scrubbing of CO 2 was realized. For the evaluation, a pilot plant was built, on which also the removal efficiency of CO 2 was verified at different solids flow rates. The model results were compared with experimental data in terms of percentage removal efficiency of carbon dioxide. The comparison showed that the EGPF model agreed well with the experimental data satisfactorily. The removal efficiency was observed to be mainly influenced by flow rates of adsorbent and CO 2 concentration.

  18. Kinetics of Anaerobic Digestion of Palm Oil Mill Effluent (POME) in Double-Stage Batch Bioreactor with Recirculation and Fluidization of Microbial Immobilization Media

    Science.gov (United States)

    Ramadhani, L. I.; Damayanti, S. I.; Sudibyo, H.; Budhijanto, W.

    2018-03-01

    Palm Oil Mill Effluent (POME) becomes big problem for palm oil industries, especially for Crude Palm Oil (CPO) industry since it produces 3 tons of POME for every ton of CPO production.The high amount of organic loading in POME makes it potential as a substrate in anaerobic digestion to generate biogas as renewable energy source. The most common but conventional method by using open lagoon is still preferred for most CPO industry in Indonesia to treat POME because of its simplicity and easiness. However, this method creates new major problem for the water bodies since it has no significant chemical oxygen demand (COD) removal and needs wide area. Besides, greenhouse gas (CH4) is also released during the process. An innovation was made in this study by designing vertical column process equipment to run an anaerobic digestion of POME. The vertical column was functioned as anaerobic fluidized bed reactor (AFBR). To enhance the digestion rate in AFBR, natural zeolite was used as the immobilization media and the inoculum was taken from digested biodiesel waste. This research aimed to determine the kinetic constants of double-stage anaerobic POME digestion for COD removal and biogas production. To get close to the real condition, the POME used in this experiment had 8,000 mg/L of sCOD (the real sCOD was ±16,000 mg/L). The experiment was conducted under room temperature with up-flow velocity between 1.75 and 2.3 cm/s for optimum fluidization of immobilization media.

  19. Fluidization of Group B particles with a rotating distributor

    OpenAIRE

    Sobrino Fernández, Celia; Almendros Ibáñez, José Antonio; Santana Santana, Domingo José; Vega Blázquez, Mercedes de

    2008-01-01

    A novel rotating distributor fluidized bed is presented. The distributor is a rotating perforated plate, with 1% open-area ratio. This work evaluates the performance of this new design, considering pressure drop, Δp, and quality of fluidization. Bed fluidization was easily achieved with the proposed device, improving the solid mixing and the quality of fluidization. In order to examine the effect of the rotational speed of the distributor plate on the hydrodynamic behavior of the bed...

  20. Probability analysis of MCO over-pressurization during staging

    International Nuclear Information System (INIS)

    Pajunen, A.L.

    1997-01-01

    The purpose of this calculation is to determine the probability of Multi-Canister Overpacks (MCOs) over-pressurizing during staging at the Canister Storage Building (CSB). Pressurization of an MCO during staging is dependent upon changes to the MCO gas temperature and the build-up of reaction products during the staging period. These effects are predominantly limited by the amount of water that remains in the MCO following cold vacuum drying that is available for reaction during staging conditions. Because of the potential for increased pressure within an MCO, provisions for a filtered pressure relief valve and rupture disk have been incorporated into the MCO design. This calculation provides an estimate of the frequency that an MCO will contain enough water to pressurize beyond the limits of these design features. The results of this calculation will be used in support of further safety analyses and operational planning efforts. Under the bounding steady state CSB condition assumed for this analysis, an MCO must contain less than 1.6 kg (3.7 lbm) of water available for reaction to preclude actuation of the pressure relief valve at 100 psid. To preclude actuation of the MCO rupture disk at 150 psid, an MCO must contain less than 2.5 kg (5.5 lbm) of water available for reaction. These limits are based on the assumption that hydrogen generated by uranium-water reactions is the sole source of gas produced within the MCO and that hydrates in fuel particulate are the primary source of water available for reactions during staging conditions. The results of this analysis conclude that the probability of the hydrate water content of an MCO exceeding 1.6 kg is 0.08 and the probability that it will exceed 2.5 kg is 0.01. This implies that approximately 32 of 400 staged MCOs may experience pressurization to the point where the pressure relief valve actuates. In the event that an MCO pressure relief valve fails to open, the probability is 1 in 100 that the MCO would experience

  1. Pressure-charged steam fluidized bed drying of brown coal. Process optimization by means of fine grain drying; Druckaufgeladene Dampfwirbelschicht-Trocknung (DDWT) von Braunkohlen. Verfahrensoptimierung mittels Feinkorntrocknung

    Energy Technology Data Exchange (ETDEWEB)

    Lechner, Stefan; Hoehne, Olaf; Krautz, Hans Joachim [Brandenburgische Technische Univ., Cottbus (Germany). Lehrstuhl Kraftwerkstechnik

    2008-07-01

    Since the year 2002, the professorship power plant technology of the Brandenburg Technical University Cottbus (Federal Republic of Germany) investigates the pressure-charged steam fluidized bed drying of brown coals on the basis of a power station-integrated procedure. At the test facility with a throughput of up to 500 kg/h numerous attempts with fine coal of the granulation between 0 and 6.3 mm are accomplished. Regarding to the optimization of the heat transition for the decrease of the investment costs of the complete system, the dryer was upgraded for the parameters of the fine grain drying process. The fine grain drying process is compared with the coarse grain drying process. First operating results are presented.

  2. Pressurized fluidized-bed hydroretorting of eastern oil shales. Volume 2, Task 3, Testing of process improvement concepts: Final report, September 1987--May 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    This final report, Volume 2, on ``Process Improvement Concepts`` presents the results of work conducted by the Institute of Gas Technology (IGT), the Illinois Institute of Technology (IIT), and the Ohio State University (OSU) to develop three novel approaches for desulfurization that have shown good potential with coal and could be cost-effective for oil shales. These are (1) In-Bed Sulfur Capture using different sorbents (IGT), (2) Electrostatic Desulfurization (IIT), and (3) Microbial Desulfurization and Denitrification (OSU and IGT). Results of work on electroseparation of shale oil and fines conducted by IIT is included in this report, as well as work conducted by IGT to evaluate the restricted pipe discharge system. The work was conducted as part of the overall program on ``Pressurized Fluidized-Bed Hydroretorting of Eastern Oil Shales.``

  3. Pressure-induced staging transitions and stage disorder in dilute potassium-graphite intercalation compounds

    International Nuclear Information System (INIS)

    Fischer, J.E.; Kim, H.J.

    1987-01-01

    We extend our previous study of high-pressure staging transitions and stage disorder to dilute potassium-graphite intercalation compounds, using the Hendricks-Teller analysis of elastic neutron scattering (00L) profiles measured at 300 K over a broad q range. The dilute regime begins at a concentration [K]/[C]approx. <1/33, all samples in this regime behaving qualitatively the same at high pressure. A continuous transition starts immediately near P = 0, leading to a well-ordered higher stage with no apparent connection to in-plane density or structure. This is stable only over a small range, transforming abruptly at slightly higher P to a still higher stage or stage mixture, the index of which is consistent with the specific in-plane density imposed by commensurate 2 x 2 lockin. Disorder generally increases with average stage index (i.e., with increasing P or decreasing [K]/[C] ratio), consistent with the theory of Kirczenow. Disorder in the most dilute samples is better represented by a skewed distribution of many stage packages than by a random mixture of two or three different stage cells

  4. The last stage of Earth's formation: Increasing the pressure

    Science.gov (United States)

    Lock, S. J.; Stewart, S. T.; Mukhopadhyay, S.

    2017-12-01

    A range of high-energy, high-angular momentum (AM) giant impacts have been proposed as a potential trigger for lunar origin. High-energy, high-AM collisions create a previously unrecognized planetary object, called a synestia. Terrestrial synestias exceed the corotation limit for a rocky planet, forming an extended structure with a corotating inner region and disk-like outer region. We demonstrate that the internal pressures of Earth-like planets do not increase monotonically during the giant impact stage, but can vary substantially in response to changes in rotation and thermal state. The internal pressures in an impact-generated synestia are much lower than in condensed, slowly rotating planets of the same mass. For example, the core-mantle boundary (CMB) pressure can be as low as 60 GPa for a synestia with Earth mass and composition, compared to 136 GPa in the present-day Earth. The lower pressures are due to the low density and rapid rotation of the post-impact structure. After a high-AM Moon-forming impact, the internal pressures in the interior of the synestia would have increased to present-day Earth values in two stages: first by vapor condensation and second by removal of AM from the Earth during the tidal evolution of the Moon. The pressure evolution of the Earth has several implications. Metal-silicate equilibration after the impact would have occurred at much lower pressures than has previously been assumed. The observed moderately siderophile element abundances in the mantle may be consistent with equilibration at the bottom of a deep, lower-pressure magma ocean. In addition, the pressure at the CMB during cooling is coincident with, or lower than, the proposed intersection of liquid adiabats with the mantle liquidus. The mantle would hence freeze from the bottom up and there would be no basal magma ocean. The subsequent pressure increase and tidal heating due to the Moon's orbital evolution likely induces melting in the lowermost mantle. Increasing

  5. Update on status of fluidized-bed combustion technology

    International Nuclear Information System (INIS)

    Stallings, J.; Boyd, T.; Brown, R.

    1992-01-01

    During the 1980s, fluidized-bed combustion technology has become the dominant technology for solid-fuel-fired power generation systems in the United States. Atmospheric fluidized beds as large as 160 MWe in capacity are now in operation, while pressurized systems reaching 80 MWe have started up in the last year. The commercial status, boiler performance, emissions, and future developments for both atmospheric and pressurized fluidized-bed combustion systems are discussed

  6. A two-stage microbial fuel cell and anaerobic fluidized bed membrane bioreactor (MFC-AFMBR) system for effective domestic wastewater treatment.

    KAUST Repository

    Ren, Lijiao

    2014-03-10

    Microbial fuel cells (MFCs) are a promising technology for energy-efficient domestic wastewater treatment, but the effluent quality has typically not been sufficient for discharge without further treatment. A two-stage laboratory-scale combined treatment process, consisting of microbial fuel cells and an anaerobic fluidized bed membrane bioreactor (MFC-AFMBR), was examined here to produce high quality effluent with minimal energy demands. The combined system was operated continuously for 50 days at room temperature (∼25 °C) with domestic wastewater having a total chemical oxygen demand (tCOD) of 210 ± 11 mg/L. At a combined hydraulic retention time (HRT) for both processes of 9 h, the effluent tCOD was reduced to 16 ± 3 mg/L (92.5% removal), and there was nearly complete removal of total suspended solids (TSS; from 45 ± 10 mg/L to <1 mg/L). The AFMBR was operated at a constant high permeate flux of 16 L/m(2)/h over 50 days, without the need or use of any membrane cleaning or backwashing. Total electrical energy required for the operation of the MFC-AFMBR system was 0.0186 kWh/m(3), which was slightly less than the electrical energy produced by the MFCs (0.0197 kWh/m(3)). The energy in the methane produced in the AFMBR was comparatively negligible (0.005 kWh/m(3)). These results show that a combined MFC-AFMBR system could be used to effectively treat domestic primary effluent at ambient temperatures, producing high effluent quality with low energy requirements.

  7. Automation and control in industrial installations. Its application in pressurized fluidized bed plants, coal washeries etc. Automatizacion y control en instalaciones industriales. Su aplicacion en centrales de lecho fluido a presion, lavaderos de carbon etc

    Energy Technology Data Exchange (ETDEWEB)

    Trujillo Tarifa, R. (ENDESA, Madrid (Spain))

    1988-01-01

    This paper presents the automation and electronic control systems, based on the most advanced technologies on the market. The most recent techniques concerning industrial plant supervision and the processing of information obtained from the above mentioned systems are discussed. Intraplant communications between the control systems and the supervision computers as well as communications among cascade computers are described. These studies are applied to specific cases of pressurized fluidized bed plants, coal washing plants, coal yards, etc.

  8. Experimental studies on combustion of composite biomass pellets in fluidized bed.

    Science.gov (United States)

    Guo, Feihong; Zhong, Zhaoping

    2017-12-01

    This work presents studies on the combustion of Composite Biomass Pellets (CBP S ) in fluidized bed using bauxite particles as the bed material. Prior to the combustion experiment, cold-flow characterization and thermogravimetric analysis are performed to investigate the effect of air velocity and combustion mechanism of CBP S . The cold-state test shows that CBPs and bauxite particles fluidize well in the fluidized bed. However, because of the presence of large CBPs, optimization of the fluidization velocity is rather challenging. CBPs can gather at the bottom of the fluidized bed at lower gas velocities. On the contrary, when the velocity is too high, they accumulate in the upper section of the fluidized bed. The suitable fluidization velocity for the system in this study was found to be between 1.5-2.0m/s. At the same time, it is found that the critical fluidization velocity and the pressure fluctuation of the two-component system increase with the increase of CBPs mass concentration. The thermogravimetric experiment verifies that the combustion of CBPs is a first-order reaction, and it is divided into three stages: (i) dehydration, (ii) release and combustion of the volatile and (iii) the coke combustion. The combustion of CBPs is mainly based on the stage of volatile combustion, and its activation energy is greater than that of char combustion. During the combustion test, CBP S are burned at a 10kg/h feed rate, while the excess air is varied from 25% to 100%. Temperatures of the bed and flue gas concentrations (O 2 , CO, SO 2 and NO) are recorded. CBPs can be burnt stably, and the temperature of dense phase is maintained at 765-780°C. With the increase of the air velocity, the main combustion region has a tendency to move up. While the combustion is stable, O 2 and CO 2 concentrations are maintained at about 7%, and 12%, respectively. The concentration of SO 2 in the flue gas after the initial stage of combustion is nearly zero. Furthermore, NO concentration

  9. Advances in fluidized bed technologies

    International Nuclear Information System (INIS)

    Mutanen, K.

    1992-01-01

    Atmospheric fluidized bed combustion (AFBC) has advanced into industrial cogeneration and utility-scale electric generation. During the 1980's AFBC became the dominant technology in the United States for power generation systems fired with solid fuels. Development of pressurized fluidized bed combustion/gasification (PFB/G) has grown rapidly from small bench-scale rigs to large pilot and demonstration plants. AFBC as large as 160 MWe in capacity are now in operation, while pressurized combustion systems generating 80 MWe have started up two years ago. The major driving forces behind development of fluidized bed technologies are all the time strictening emission control regulations, need for fuel flexibility, repowering of older power plants and need for higher efficiency in electricity generation. Independent power producers (IPP) and cogenerators were the first ones in the United States who accepted AFBC for wide commercial use. Their role will be dominant in the markets of the 1990's also. Developers of AFBC systems are working on designs that reduce investment costs, decrease emissions and offer even higher reliability and availability in utility-scale applications while developers of PFBC/G work on designs that increase plant efficiencies, allow modular construction, decrease emissions further and reduce the cost of generating power. This paper presents technological background, commercial status, boiler performance, emissions and future developments for both AFBC and PFBC/G systems

  10. Pressurized fluidized-bed hydroretorting of Eastern oil shales -- Beneficiation. Topical report for Task 4, Beneficiation research

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Lau, F.S.; Mensinger, M.C. [Institute of Gas Technology, Chicago, IL (United States); Schultz, C.W.; Mehta, R.K.; Lamont, W.E. [Alabama Univ., University, AL (United States); Chiang, S.H.; Venkatadri, R. [Pittsburgh Univ., PA (United States); Misra, M. [Nevada Univ., Reno, NV (United States)

    1992-05-01

    The Mineral Resources Institute at the University of Alabama, along with investigators from the University of Pittsburgh and the University of Nevada-Reno, have conducted a research program on the beneficiation, of Eastern oil shales. The objective of the research program was to evaluate and adapt those new and emerging technologies that have the potential to improve the economics of recovering oil from Eastern oil shales. The technologies evaluated in this program can be grouped into three areas: fine grinding kerogen/mineral matter separation, and waste treatment and disposal. Four subtasks were defined in the area of fine grinding. They were as follows: Ultrasonic Grinding, Pressure Cycle Comminution, Stirred Ball Mill Grinding, and Grinding Circuit Optimization. The planned Ultrasonic grinding research was terminated when the company that had contracted to do the research failed. Three technologies for effecting a separation of kerogen from its associated mineral matter were evaluated: column flotation, the air-sparged hydrocyclone, and the LICADO process. Column flotation proved to be the most effective means of making the kerogen/mineral matter separation. No problems are expected in the disposal of oil shale tailings. It is assumed that the tailings will be placed in a sealed pond and the water recycled to the plant as is the normal practice. It may be advantageous, however, to conduct further research on the recovery of metals as by-products and to assess the market for tailings as an ingredient in cement making.

  11. NO{sub x}, N{sub 2}O and SO{sub 2} emissions from pressurized fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Korpela, T.; Lu, Y. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Economic Energy and Power Plant Engineering

    1996-12-01

    This project continues the analysis of available data from the experimental work at the Otaniemi PFBC test rig using various solid fuels. The study concentrates on the emission and control of NO{sub x} N{sub 2}O, and SO{sub 2} under pressurized conditions. The aim of the study is to prepare the database from the available data and make empirical correlations for estimating nitrogen oxide emissions and sulfur capture from PFBC as a function of significant operating parameters and fuel properties. As the first generation of an empirical model, multiple linear regression was developed for predicting NO{sub x}, N{sub 2}O and SO{sub 2} emissions from PFBC. These correlations may facilitate preliminary FBC design by estimating NO{sub x}, N{sub 2}O and SO{sub 2} emissions. On the basis of statistical inference, the operating conditions employed and the fuel properties selected in the correlations may lend insight into the mechanisms of the formation and destruction of NO{sub x}, N{sub 2}O and SO{sub 2}. (author)

  12. Air Distributor Designs for Fluidized Bed Combustors: A Review

    Directory of Open Access Journals (Sweden)

    A. Shukrie

    2016-06-01

    Full Text Available Fluidized bed combustion (FBC has been recognized as one of the suitable technologies for converting a wide variety of biomass fuels into energy. One of the key factors affecting the successful operation of fluidized bed combustion is its distributor plate design. Therefore, the main purpose of this article is to provide a critical overview of the published studies that are relevant to the characteristics of different fluidized bed air distributor designs. The review of available works display that the type of distributor design significantly affects the operation of the fluidized bed i.e., performance characteristics, fluidization quality, air flow dynamics, solid pattern and mixing caused by the direction of air flow through the distributors. Overall it is observed that high pressure drop across the distributor is one of the major draw backs of the current distributor designs. However, fluidization was stable in a fluidized bed operated at a low perforation ratio distributor due to the pressure drop across the distributor, adequate to provide uniform gas distribution. The swirling motion produced by the inclined injection of gas promotes lateral dispersion and significantly improves fluidization quality. Lastly, the research gaps are highlighted for future improvement consideration on the development of efficient distributor designs.

  13. Staged catalytic gasification/steam reforming of pyrolysis oil

    NARCIS (Netherlands)

    van Rossum, G.; Kersten, Sascha R.A.; van Swaaij, Willibrordus Petrus Maria

    2009-01-01

    Gasification/steam reforming of pyrolysis oil was studied in a staged reactor concept, which consisted of an inert fluidized bed and a catalytic fixed bed. Methane and C2−C3 free syngas is produced at a single temperature around 800 °C at atmospheric pressure. By lowering the temperature of the

  14. CORRELATION OF OCULAR PERFUSION PRESSURE AND INTRAOCULAR PRESSURE CHANGES DURING HAEMODIALYSIS IN END STAGE RENAL DISEASE- AN OBSERVATIONAL STUDY

    Directory of Open Access Journals (Sweden)

    T. R. Anuradha

    2017-12-01

    Full Text Available BACKGROUND Chronic kidney disease patients on haemodialysis have a transient raise in intraocular pressure and decrease in ocular perfusion pressure. This is used in early detection of glaucomatous optic nerve damage and subsequent irreversible visual loss. MATERIALS AND METHODS 100 chronic kidney disease patients under haemodialysis in the nephrology department, Stanley medical college for more than one month were included in the study. We recorded complete history, and all participants were subjected to Intraocular pressure and blood pressure measurement at 3 different timings during haemodialysis session. Mean Arterial Pressure (MAP, Ocular Perfusion Pressure (OPP, Systolic Ocular Perfusion Pressure (SOPP, Diastolic Ocular Perfusion Pressure (DOPP and Mean Ocular Perfusion Pressure (MOPP were calculated. RESULTS Mean IOP from the initiation to the end of haemodialysis was found to be increased. Mean arterial pressure, ocular perfusion pressure, systolic ocular perfusion pressure, diastolic ocular perfusion pressure, mean ocular perfusion pressure was found to be decreased from the initiation to the end of haemodialysis. At the end of study period, 10% were found to develop early glaucomatous field defects and early optic nerve head changes in both eyes at follow-up. CONCLUSION Our study reveals the importance of screening and monitoring of intraocular pressure and characteristic early optic nerve head changes and early visual field changes of glaucoma in end-stage renal disease patients who are on haemodialysis.

  15. Pressure, stress, and strain distribution in the double-stage diamond anvil cell

    Energy Technology Data Exchange (ETDEWEB)

    Lobanov, Sergey S., E-mail: slobanov@carnegiescience.edu [Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia 20015 (United States); V.S. Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk 630090 (Russian Federation); Prakapenka, Vitali B.; Prescher, Clemens [Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60632 (United States); Konôpková, Zuzana; Liermann, Hanns-Peter [Photon Science DESY, D-22607 Hamburg (Germany); Crispin, Katherine L. [Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia 20015 (United States); Zhang, Chi [Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics CAS, Beijing 100029 (China); Goncharov, Alexander F. [Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia 20015 (United States); Key Laboratory of Materials Physics, Institute of Solid State Physics CAS, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China)

    2015-07-21

    Double stage diamond anvil cells (DACs) of two designs have been assembled and tested. We used a standard symmetric DAC with flat or beveled culets as a primary stage and CVD microanvils machined by a focused ion beam as a second. We evaluated pressure, stress, and strain distributions in gold and a mixture of gold and iron as well as in secondary anvils using synchrotron x-ray diffraction with a micro-focused beam. A maximum pressure of 240 GPa was reached independent of the first stage anvil culet size. We found that the stress field generated by the second stage anvils is typical of conventional DAC experiments. The maximum pressures reached are limited by strains developing in the secondary anvil and by cupping of the first stage diamond anvil in the presented experimental designs. Also, our experiments show that pressures of several megabars may be reached without sacrificing the first stage diamond anvils.

  16. Prediction of pressure between packers of staged fracturing pipe strings in high-pressure deep wells and its application

    Directory of Open Access Journals (Sweden)

    Fuxiang Zhang

    2015-03-01

    Full Text Available Addressing to the deteriorated load conditions of working string and packers caused by annular pressure drop between packers during the staged stimulation of high-pressure deep well, one 2D temperature field transient prediction model for borehole under injecting conditions which considers such influences as friction heat, convection heat exchange was set up, based on energy conservation principle and borehole heat transfer theory. By means of analyzing the influences of borehole temperature and pressure changes on the annular volume between packers, and in combination with borehole temperature transient prediction model, annular fluid PVT equations of state, radial deformation model of tubing and formation transient seepage equation, a typical high-pressure deep well inter-packer annular pressure prediction model was established. Taking a high-pressure gas well in Tarim Oilfield for example, the inter-packer annular pressure prediction was conducted, on which, the mechanical analysis on packers and working strings was carried out. The analysis results show that although the pipe string is safe in the viewpoint of conventional design methods, it is still susceptible to failure after the annular pressure drop between packers was taken into consideration. Such factor should be fully considered in the design of staged stimulation pipe strings, and this prediction model provides new thoughts for the optimal design of high-pressure deep well staged stimulation pipe strings.

  17. Uterine Prolapse Following Fundal Pressure in the First Stage of ...

    African Journals Online (AJOL)

    ANNALS

    through the cervical os as they were both high up in the pelvis. An attempt at replacing the prolapsed cervix to its normal position failed. Figure 1. Uterovaginal prolapse with oedematous cervix. A diagnosis of multipara with a second degree uterine prolapse most likely due to fundal pressure and obstructed labor was made.

  18. Preliminary use of a hydrogel containing enzymes in the treatment of stage II and stage III pressure ulcers.

    Science.gov (United States)

    Parnell, Linda K S; Ciufi, Brandi; Gokoo, Charles F

    2005-08-01

    Considerable progress has been made in the prevention and treatment of pressure ulcers but they remain a significant healthcare problem, particularly among the elderly. Treatment may include the use of wound dressings such as hydrogels as well as debridement products that contain relatively high concentrations of various enzymes. Unlike enzymes found in debridement products, low concentrations of endopeptidase enzymes can cleave to denatured proteins. Many endopeptidases have been reported to enhance the healing process. To evaluate the effect of a hydrogel wound dressing containing a combination of endopeptidases on pressure ulcers, a 12-week prospective preliminary study was conducted involving 10 nursing home patients with Stage II (n = 3) or Stage III (n = 7) ulcers that had failed to respond to previous treatments. Seven subjects (three with Stage II ulcers and four with Stage III ulcers) completed the study. Healing was based on wound closure by re-epithelialization as determined by area measurement and clinical assessment. All three Stage II ulcers and two of the Stage III ulcers healed completely; four Stage III ulcers were categorized as healing (>60% improvement) after 12 weeks of care. No dressing-related adverse events occurred and subject acceptance of the product, including comfort, was high. These results suggest that additional studies designed to define the possible contribution of endopeptidase enzymes in wound healing are warranted.

  19. Parameters critical to the morphology of fluidization craters

    Science.gov (United States)

    Siegal, B. S.; Gold, D. P.

    1973-01-01

    In order to study further the role of fluidization on the moon, a laboratory investigation was undertaken on two particulate material size fractions to determine the effect of variables, such as, duration of gas streaming, gas pressure, and 'regolith' thickness on the morphology of fluidization craters. A 3.175-mm cylindrical vent was used to simulate a gas streaming conduit. Details of the fluidization chamber are discussed together with questions of experimental control, aspects of nomenclature, crater measurements, and the effect of variables.

  20. Synchronized oscillations and acoustic fluidization in confined granular materials

    Science.gov (United States)

    Giacco, F.; de Arcangelis, L.; Ciamarra, M. Pica; Lippiello, E.

    2018-01-01

    According to the acoustic fluidization hypothesis, elastic waves at a characteristic frequency form inside seismic faults even in the absence of an external perturbation. These waves are able to generate a normal stress which contrasts the confining pressure and promotes failure. Here, we study the mechanisms responsible for this wave activation via numerical simulations of a granular fault model. We observe the particles belonging to the percolating backbone, which sustains the stress, to perform synchronized oscillations over ellipticlike trajectories in the fault plane. These oscillations occur at the characteristic frequency of acoustic fluidization. As the applied shear stress increases, these oscillations become perpendicular to the fault plane just before the system fails, opposing the confining pressure, consistently with the acoustic fluidization scenario. The same change of orientation can be induced by external perturbations at the acoustic fluidization frequency.

  1. Second generation pressurized fluidized-bed combustion (PFBC) research and development, Phase 2 --- Task 4, carbonizer testing. Volume 2, Data reconciliation

    Energy Technology Data Exchange (ETDEWEB)

    Froehlich, R.; Robertson, A.; Vanhook, J.; Goyal, A.; Rehmat, A.; Newby, R.

    1994-11-01

    During the period beginning November 1991 and ending September 1992, a series of tests were conducted at Foster Wheeler Development Corporation in a fluidized-bed coal carbonizer to determine its performance characteristics. The carbonizer was operated for 533 hours in a jetting fluidized-bed configuration during which 36 set points (steady-state periods) were achieved. Extensive data were collected on the feed and product stream compositions, heating values, temperatures, and flow rates. With these data, elemental and energy balances were computed to evaluate and confirm accuracy of the data. The carbonizer data were not as self-consistent as could be desired (balance closure imperfection). A software package developed by Science Ventures, Inc., of California, called BALAID, was used to reconcile the carbonizer data; the details of the reconciliation have been given in Volume 1 of this report. The reconciled data for the carbonizer were rigorously analyzed, correlations were developed, and the model was updated accordingly. The model was then used in simulating each of the 36 steady-state periods achieved in the pilot plant. The details are given in this Volume one. This Volume 2 provides details of the carbonizer data reconciliation.

  2. Steam gasification of coal at low-medium (600-800{sup o}C) temperature with simultaneous CO{sub 2} capture in fluidized bed at atmospheric pressure: The effect of inorganic species. 1. Literature review and comments

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Toledo, J.M.; Molina, G. [Universidad Complutense de Madrid, Madrid (Spain). Dept. for Chemical Engineering

    2006-08-30

    This paper addresses the H{sub 2} production with simultaneous CO{sub 2} capture by steam gasification of coal in a fluidized bed, at low/medium temperatures (600-800{sup o}C) and atmospheric pressure. This work is mainly aimed at reviewing the effects of the inorganic species present in the matrix of the coal or added to the gasifier bed. The most promising species seems to be the calcined limestone (CaO), which intervenes in the overall gasification reaction network in at least five different types of reactions. The effectiveness of the CaO for CO{sub 2} capture in the coal gasifier is, therefore, affected/influenced by the other four simultaneous or competitive types of reactions in the gasifier. The effects of the temperature in the gasifier and of the (CaO/coal) ratio fed to the gasifier are finally reviewed and discussed in detail.

  3. Staging properties of potassium-ammonia ternary graphite intercalation compounds at high ammonia pressure

    Science.gov (United States)

    Qian, X. W.; Solin, S. A.

    1989-04-01

    The pressure dependence of the (00l) x-ray diffraction patterns of the ternary graphite intercalation compound K(NH3)xC24 has been studied in the range 0.5-11 kbar (for which x~4.5) using a diamond anvil cell. A special apparatus for loading the cell with liquid ammonia at room temperature has been constructed and is briefly described. In these experiments, the pressure-transmitting fluid was also an intercalant, namely ammonia. Therefore, the chemical potential of this species was linearly coupled to the applied pressure in contrast to the usual case where the pressure-transmitting fluid is chemically passive. The pressure dependences of the basal spacings and of the relative intensities of key reflections have been measured, as have the compressibilities of the stage-1 and stage-2 components of the two-phase system. Basal-spacing anomalies and anomalies in the relative intensities occur at pressures of ~3.5 and 8.0 kbar and are tentatively attributed to in-plane coordination changes in the potassium-ammonia ratio. Using thermodynamic arguments and Le Chatelier's principle we show quantitatively that a staging phase transition from pure stage-1 phase to an admixture of stage-1 and stage-2 is expected with increased pressure above 10 bar in agreement with experiment. The saturation ammonia compositions (x values) of the admixed stages are found to be 4.5 and 5.4 for the stage-1 and -2 components, respectively. This result is interpreted as evidence that the composition is not sterically limited but is determined by the binding energy of ammonia for potassium and by the perturbation to this energy from the guest-host interaction.

  4. Generation of High Pressure Oxygen via Electrochemical Pumping in a Multi-Stage Electrolysis Stack

    Science.gov (United States)

    Setlock, John A (Inventor); Green, Robert D (Inventor); Farmer, Serene (Inventor)

    2017-01-01

    An oxygen pump can produce high-purity high-pressure oxygen. Oxygen ions (O(2-)) are electrochemically pumped through a multi-stage electrolysis stack of cells. Each cell includes an oxygen-ion conducting solid-state electrolyte between cathode and anode sides. Oxygen dissociates into the ions at the cathode side. The ions migrate across the electrolyte and recombine at the anode side. An insulator is between adjacent cells to electrically isolate each individual cell. Each cell receives a similar volt potential. Recombined oxygen from a previous stage can diffuse through the insulator to reach the cathode side of the next stage. Each successive stage similarly incrementally pressurizes the oxygen to produce a final elevated pressure.

  5. Low-pressure reversible axial fan designed with different specific work of elementary stages

    Directory of Open Access Journals (Sweden)

    Bogdanović Božidar P.

    2012-01-01

    Full Text Available Low-pressure axial fan impellers designed according to the principle of equal specific work of all elementary stages have blades whose profile near the fan hub is under a significantly larger inclination angle than at the impeller periphery. In order to minimize the spatial curvature of the fan blades and the fan hub length, impeller blades of low-pressure axial fans can be designed with different specific work of elementary stages, so that the specific work of elementary stages is smaller at the hub than at the periphery. This paper presents the operating characteristics of a low-pressure reversible axial fan with straight blade profiles, designed with different specific work of elementary stages. The fan was tested on a standard test rig, with air intake loading on the suction side of the fan.

  6. Gasification of rice husk in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mansaray, K.G.

    1998-12-31

    The development of two mathematical models which simulate the performance of a dual distributor fluidized bed gasifier was described. The gasification of rice husks in the gasifier using air as the sole gasifying agent was investigated. The four stages of the study were: (1) modification of the existing fluidized bed gasifier and data acquisition system, (2) preliminary experimentation to assess the suitability of rice husks for gasification to determine the feasible range of operating conditions for fluidized bed gasification of rice husks and to obtain data for proper design of thermochemical conversion systems, (3) development of mathematical models to predict the performance of the fluidized bed gasification system, and (4) experimentation to investigate the effects of various operating variables on the performance of the gasifier and provide data to evaluate the validity of the models.

  7. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  8. Abnormalities of plantar pressure distribution in early, intermediate, and late stages of diabetic neuropathy.

    Science.gov (United States)

    Sacco, Isabel C N; Hamamoto, Adriana N; Tonicelli, Lucas M G; Watari, Ricky; Ortega, Neli R S; Sartor, Cristina D

    2014-09-01

    Inconsistent findings with regard to plantar pressure while walking in the diabetic population may be due to the heterogeneity of the studied groups resulting from the classification/grouping criteria adopted. The clinical diagnosis and classification of diabetes have inherent uncertainties that compromise the definition of its onset and the differentiation of its severity stages. A fuzzy system could improve the precision of the diagnosis and classification of diabetic neuropathy because it takes those uncertainties into account and combines different assessment methods. Here, we investigated how plantar pressure abnormalities evolve throughout different severity stages of diabetic polyneuropathy (absent, n=38; mild, n=20; moderate, n=47; severe, n=24). Pressure distribution was analysed over five areas while patients walked barefoot. Patients with mild neuropathy displayed an increase in pressure-time integral at the forefoot and a lower peak pressure at the heel. The peak and pressure-time integral under the forefoot and heel were aggravated in later stages of the disease (moderate and severe) compared with early stages of the disease (absent and mild). In the severe group, lower pressures at the lateral forefoot and hallux were observed, which could be related to symptoms that develop with the aggravation of neuropathy: atrophy of the intrinsic foot muscles, reduction of distal muscle activity, and joint stiffness. Although there were clear alterations over the forefoot and in a number of plantar areas with higher pressures within each severity stage, they did not follow the aggravation evolution of neuropathy classified by the fuzzy model. Based on these results, therapeutic interventions should begin in the early stages of this disease to prevent further consequences of the disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Fundal pressure during the second stage of labor in a tertiary obstetric center: a prospective analysis.

    Science.gov (United States)

    Moiety, Fady M Shawky; Azzam, Amal Z

    2014-04-01

    To ascertain whether uterine fundal pressure should have a role in the management of the second stage of labor and to determine its prevalence, benefits and adverse maternal-fetal outcomes. This was a prospective observational study set in a tertiary teaching and research obstetric hospital. A total of 8097 women in labor between 37 and 42 gestational weeks with a singleton cephalic presentation were enrolled. Subjects were subdivided into two groups: fundal pressure group (n=1974 women) and control group (n=6123 women). The primary outcome measure was the duration of the second stage. The secondary outcome measures were maternal outcomes (immediate or delayed) and neonatal outcomes. The prevalence of fundal pressure in our center was 24.38%. Fundal pressure maneuver significantly shortened the duration of the second stage among primiparous women, increased the risk of severe perineal laceration and admission to neonatal intensive care unit in comparison to the non-fundal group. Delayed maternal outcomes showed significant increase in dyspareunia and de novo stress urinary incontinence in the fundal pressure group. Although fundal pressure maneuver shortens the duration of the second stage of labor among primiparous women, it should not be used except when indicated, and under strict guidelines owing to its adverse maternal and fetal outcomes. © 2014 The Authors. Journal of Obstetrics and Gynaecology Research © 2014 Japan Society of Obstetrics and Gynecology.

  10. Surgical reconstruction of pressure ulcer defects: a single- or two-stage procedure?

    LENUS (Irish Health Repository)

    Laing, Tereze A

    2012-02-01

    BACKGROUND: The surgical management of pressure ulcers traditionally involved staged procedures, with initial debridement of necrotic or infected material followed by reconstruction at a later date when the wound was deemed viable and free of gross infection. However, over the past decade, it has been suggested that a single-stage procedure, combining initial debridement and definitive reconstruction, may provide advantages over staged surgery. We present our experience with the staged approach and review the current evidence for both methods. SUBJECTS AND SETTINGS: : We reviewed medical records of all patients referred to our service for pressure ulcer management between October 2001 and October 2007. The National Rehabilitation Hospital is the national center in Ireland for primary rehabilitation of adults and children suffering from spinal and brain injury, serving patients locally and from around the country. METHODS: All subjects who were managed surgically underwent a 2-stage procedure, with initial debridement and subsequent reconstruction. The main outcome measures were length of hospital stay, postoperative morbidity and mortality, and time to complete ulcer healing. RESULTS: Forty-one of 108 patients with 58 pressure ulcers were managed surgically. All patients underwent initial surgical debridement and 20 patients underwent subsequent pressure ulcer reconstruction. Postreconstructive complications occurred in 5 patients (20%). The mean time to complete ulcer healing was 17.4 weeks. Partial flap necrosis occurred in 3 patients, but there were no episodes of flap failure. CONCLUSIONS: We achieved favorable results with a 2-stage reconstruction technique and suggest that the paucity of evidence related to single-stage procedures does not support a change in surgical management.

  11. Theoretical evaluation of the efficiency of gas single-stage reciprocating compressor medium pressure units

    Science.gov (United States)

    Busarov, S. S.; Vasil'ev, V. K.; Busarov, I. S.; Titov, D. S.; Panin, Ju. N.

    2017-08-01

    Developed earlier and tested in such working fluid as air, the technology of calculating the operating processes of slow-speed long-stroke reciprocating stages let the authors to obtain successful results concerning compression of gases to medium pressures in one stage. In this connection, the question of the efficiency of the application of slow-speed long-stroke stages in various fields of technology and the national economy, where the working fluid is other gas or gas mixture, is topical. The article presents the results of the efficiency evaluation of single-stage compressor units on the basis of such stages for cases when ammonia, hydrogen, helium or propane-butane mixture is used as the working fluid.

  12. Disruption of transitional stages in 24-h blood pressure in renal transplant recipients

    Directory of Open Access Journals (Sweden)

    Marcelo E Katz

    2012-03-01

    Full Text Available Patients with kidney replacement exhibit disrupted circadian rhythms. Most studies measuring blood pressure use the dipper/non-dipper classification, which does not consider analysis of transitional stages between low and high blood pressure, confidence intervals nor shifts in the time of peak, while assuming subjective onsets of night and day phases. In order to better understand the nature of daily variation of blood pressure in these patients, we analyzed 24h recordings from 41 renal transplant recipients using the non-symmetrical double-logistic fitting assessment which does not assume abruptness nor symmetry in ascending and descending stages of the blood pressure profile, and a cosine best-fitting regression method (Cosinor. Compared with matched controls, double-logistic fitting showed that the times for most of transitional stages (ascending systolic and descending systolic, diastolic and mean arterial pressure had a wider distribution along the 24 h. The proportion of individuals without daily blood pressure rhythm in the transplanted group was larger only for systolic arterial pressure, and the amplitude showed no significant difference. Furthermore, the transplant recipient group had a less pronounced slope in descending systolic and ascending mean blood pressure. Cosinor analysis confirmed the phase related changes, showing a wider distribution of times of peak (acrophases. We conclude that daily disruptions in renal transplant recipients can be explained not only by absence in diurnal variation, but also in changes in waveform-related parameters of the rhythm, and that distortions in the phase of the rhythm are the most consistent finding for the patients.

  13. Factors affecting the amounts of emissions arising from fluidized bed combustion of solid fuels

    International Nuclear Information System (INIS)

    Horbaj, P.

    1996-01-01

    The factors affecting the amounts of nitrogen oxides (NO x ) and sulfur oxides (SO x , i.e. SO 2 + SO 3 ) formed during fluidized bed combustion of fossil fuels are analyzed using both theoretical concepts and experimental data. The factors treated include temperature, excess air, fuel parameters, pressure, degree of combustion gas recycling, combustion distribution along the combustion chamber height, and sulfur trapping processes for NO x , and the Ca/S ratio, fluidized layer height and fluidization rate, granulometry and absorbent type, fluidized layer temperature, and pressure during combustion for SO x . It is concluded that fluidized bed boilers are promising power generating facilities, mitigating the environmental burden arising from fossil fuel combustion. (P.A.). 12 figs., 9 refs

  14. Multidimensionality in Fluidized Nanopowder Agglomerates

    NARCIS (Netherlands)

    De Martin, L.; Bouwman, W.G.; Van Ommen, J.R.

    2013-01-01

    recent years, the interest in fluidization as a mean to process nanoparticles is strongly increasing. Due to the small size of the nanoparticles, which makes van der Waals forces predominate, they do not fluidize as single particles but as agglomerates. Various researchers using settling experiments

  15. Pressure ulcer risk factors in persons with SCI: Part I: Acute and rehabilitation stages.

    Science.gov (United States)

    Gélis, A; Dupeyron, A; Legros, P; Benaïm, C; Pelissier, J; Fattal, C

    2009-02-01

    Pressure ulcers (PUs) are a common complication following a spinal-cord injury (SCI). Good prevention requires identifying the individuals at risk for developing PUs. Risk assessment scales used nowadays were designed on pathophysiological concepts and are not SCI-specific. Recently, an epidemiological approach to PU risk factors has been proposed to design an SCI-specific assessment tool. The first results seem quite disappointing, probably because of the level of evidence of the risk factors used. To determine PU risk factors correlated to the patients with SCI, medical care management during the acute as well as in the rehabilitation and chronic stages. This first part focuses on identifying the risk factors during the acute and rehabilitation stages. Systematic review of the literature. Six studies met our inclusion criteria. The risk factors during the acute stage of an SCI are essentially linked to care management and treatment modalities. There is insufficient evidence to make a recommendation on medical risk factors, except for low blood pressure on admission to the Emergency Room, with a moderate level of evidence. Regarding the rehabilitation stage, no study was deemed relevant. Additional observational studies are needed, for both the acute and rehabilitation stages, to improve this level of evidence. However, this systematic review unveiled the need for a carefully assessed t care management and the related practices, especially during the acute stage of an SCI.

  16. Fluidized-bed nuclear reactor

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Kunze, J.F.

    1975-01-01

    A reactor vessel containing a fluidized-bed region of particulate material including both a neutron-moderating and a fertile substance is described. A gas flow including fissile material passes through the vessel at a sufficient rate to fluidize the particulate material and at a sufficient density to support a thermal fission reaction within the fluidized-bed region. The high-temperature portion of a heat transfer system is located within the fluidized-bed region of the reactor vessel in direct contact with the fluidized particles. Heat released by fission is thereby transferred at an enhanced rate to a coolant circulating within the heat transfer system. Fission products are continuously removed from the gas flow and supplemental fissile material added during the reactor operation. (U.S.)

  17. Pressurized fluidized-bed hydroretorting of eastern oil shales. Volume 4, Task 5, Operation of PFH on beneficiated shale, Task 6, Environmental data and mitigation analyses and Task 7, Sample procurement, preparation, and characterization: Final report, September 1987--May 1991

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The objective of Task 5 (Operation of Pressurized Fluidized-Bed Hydro-Retorting (PFH) on Beneficiated Shale) was to modify the PFH process to facilitate its use for fine-sized, beneficiated Eastern shales. This task was divided into 3 subtasks: Non-Reactive Testing, Reactive Testing, and Data Analysis and Correlations. The potential environment impacts of PFH processing of oil shale must be assessed throughout the development program to ensure that the appropriate technologies are in place to mitigate any adverse effects. The overall objectives of Task 6 (Environmental Data and Mitigation Analyses) were to obtain environmental data relating to PFH and shale beneficiation and to analyze the potential environmental impacts of the integrated PFH process. The task was divided into the following four subtasks. Characterization of Processed Shales (IGT), 6.2. Water Availability and Treatment Studies, 6.3. Heavy Metals Removal and 6.4. PFH Systems Analysis. The objective of Task 7 (Sample Procurement, Preparation, and Characterization) was to procure, prepare, and characterize raw and beneficiated bulk samples of Eastern oil shale for all of the experimental tasks in the program. Accomplishments for these tasks are presented.

  18. Effects of Concord grape juice on ambulatory blood pressure in prehypertension and stage 1 hypertension123

    Science.gov (United States)

    Dohadwala, Mustali M; Hamburg, Naomi M; Holbrook, Monika; Kim, Brian H; Duess, Mai-Ann; Levit, Aaron; Titas, Megan; Chung, William B; Vincent, Felix B; Caiano, Tara L; Frame, Alissa A; Keaney, John F

    2010-01-01

    Background: Consumption of flavonoid-containing foods may be useful for the management of hypertension. Objective: We investigated whether 100% Concord grape juice lowers blood pressure in patients with prehypertension and stage 1 hypertension. Design: We conducted a double-blind crossover study to compare the effects of grape juice (7 mL · kg−1 · d−1) and matched placebo beverage on 24-h ambulatory blood pressure, stress-induced changes in blood pressure, and biochemical profile. Participants consumed each beverage for 8 wk with a 4-wk rest period between beverages. They ceased consumption of grapes and other flavonoid-containing beverages throughout the study. Results: We enrolled 64 otherwise healthy patients taking no antihypertensive medications (31% women, 42% black, age 43 ± 12 y). Baseline mean (±SD) cuff blood pressure was 138 ± 7 (systolic)/82 ± 7 (diastolic) mm Hg. No effects on the primary endpoint of 24-h mean systolic blood pressure, diastolic blood pressure, or stress-induced changes in blood pressure were observed. A secondary endpoint was nocturnal dip in systolic pressure. At baseline, nocturnal pressure was 8.3 ± 7.1% lower at night than during daytime. The mean nocturnal dip increased 1.4 percentage points after grape juice and decreased 2.3 percentage points after placebo (P = 0.005). Fasting blood glucose was 91 ± 10 mg/dL at baseline for the entire cohort. Glucose decreased 2 mg/dL after consumption of grape juice and increased 1 mg/dL after consuming the placebo (P = 0.03). Conclusions: We observed no effect of grape juice on ambulatory blood pressure in this cohort of relatively healthy individuals with modestly elevated blood pressure. Secondary analyses suggested favorable effects on nocturnal dip and glucose homeostasis that may merit further investigation. This trial was registered at clinicaltrials.gov as NCT00302809. PMID:20844075

  19. The Hampton-Gledhill 2-stage pressure risk-assessment system.

    Science.gov (United States)

    Gledhill, Lee; Hampton, Sylvie

    Pressure ulcers are largely preventable and, therefore, patients dying of large, necrotic pressure damage is an unacceptable situation. Lee Gledhill is both a nurse and a barrister and has been involved in many cases involving nurses facing court proceedings when their patients' primary cause of death is pressure ulcers. Sylvie Hampton, has acted as expert witness in some of these cases. It became obvious to the two authors that had healthcare assistants (HCAs) been more aware of how pressure damage could be detected and then prevented, some of the supervising nurses would not have been facing legal charges. The authors decided to produce a simple method of assessing first-stage skin changes for HCAs to not only recognize these changes, but also to have a framework in place describing the actions they need to take. This framework was produced as a card (the Hampton-Gledhill 2-stage pressure risk-assessment system). The card is being validated in many nursing homes and hospitals around the UK and in Jersey.

  20. 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

  1. Steam gasification of coal at low-medium (600-800{sup o}C) temperature with simultaneous CO{sub 2} capture in a bubbling fluidized bed at atmospheric pressure. 2. Results and recommendations for scaling up

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Toledo, J.M.; Molina, G. [Universidad Complutense de Madrid, Madrid (Spain). Dept. of Chemical Engineering

    2008-03-19

    A gasification gas with an H{sub 2} content as high as 80 vol %, dry basis has been obtained by gasification of coal with pure steam at 600-800{sup o}C. The gasifier used was an atmospheric and bubbling fluidized bed operating with CaO in the bed as the CO{sub 2} sorbent. The research was carried out at a small pilot plant scale with continuous feeding of coal and batch mode introduction of the CaO. The gas composition and gas quality (tar content) is given for the following variables of operation: (a) type of in-bed sorbent used, (b) the amount of CaO in the bed related to the amount of coal fed, (c) temperature in the gasifier bed, (d) weight hourly space velocity (h{sup -1}) of the coal in the gasifier, and (e) time(-on-stream). To capture CaO at atmospheric pressure, the gasification with in-bed CaO had to be carried out at low-medium (600-800{sup o}C) gasification temperatures. For this reason, the tar content in the gasification gas was high (up to 52 g/Nm{sup 3}), which lowered the value of the H{sub 2}-rich gasification raw gas. It is demonstrated that a gas rich in H{sub 2} (80 vol % H{sub 2}, dry basis), and with very low CO{sub 2} and tar contents, can be obtained only if the coal gasification, at atmospheric pressure and with pure steam, is carried out at (CaO/coal) ratios above 10-15.

  2. Acetylcysteine reduces plasma homocysteine concentration and improves pulse pressure and endothelial function in patients with end-stage renal failure

    DEFF Research Database (Denmark)

    Scholze, Alexandra; Rinder, Christiane; Beige, Joachim

    2004-01-01

    Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure.......Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure....

  3. Detecting early stage pressure ulcer on dark skin using multispectral imager

    Science.gov (United States)

    Yi, Dingrong; Kong, Linghua; Sprigle, Stephen; Wang, Fengtao; Wang, Chao; Liu, Fuhan; Adibi, Ali; Tummala, Rao

    2010-02-01

    We are developing a handheld multispectral imaging device to non-invasively inspect stage I pressure ulcers in dark pigmented skins without the need of touching the patient's skin. This paper reports some preliminary test results of using a proof-of-concept prototype. It also talks about the innovation's impact to traditional multispectral imaging technologies and the fields that will potentially benefit from it.

  4. Multiphase Flow and Fluidization Continuum and Kinetic Theory Descriptions

    CERN Document Server

    Gidaspow, Dimitri

    1994-01-01

    Useful as a reference for engineers in industry and as an advanced level text for graduate engineering students, Multiphase Flow and Fluidization takes the reader beyond the theoretical to demonstrate how multiphase flow equations can be used to provide applied, practical, predictive solutions to industrial fluidization problems. Written to help advance progress in the emerging science of multiphase flow, this book begins with the development of the conservation laws and moves on through kinetic theory, clarifying many physical concepts (such as particulate viscosity and solids pressure) and i

  5. Pyrolysis of corncobs at fluidization

    Energy Technology Data Exchange (ETDEWEB)

    Hongming Jiang; Morey, R.V. (Minnesota Univ., St. Paul, MN (United States). Dept. of Agricultural Engineering)

    1992-01-01

    Pyrolysis of corncob particles was conducted in nitrogen in an externally heated benchscale fluidized bed reactor. Test results are presented with a demonstration of their application in gasification modelling. (author).

  6. Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

    1993-01-01

    A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450[degree], over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

  7. Fluidized bed pyrolysis of bitumen-impregnated sandstone at sub-atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, J.V.; Deo, M.D.; Hanson, F.V.

    1993-03-01

    A 15.2 cm diameter fluidized bed reactor was designed, built, and operated to study the pyrolysis of oil sands at pressures slightly less than atmospheric. Fluidizing gas flow through the reactor was caused by reducing the pressure above the bed with a gas pump operating in the vacuum mode. Pyrolysis energy was supplied by a propane burner, and the hot propane combustion gases were used for fluidization. The fluidized bed pyrolysis at reduced pressure using combustion gases allowed the reactor to be operated at significantly lower temperatures than previously reported. At 450{degree}, over 80% of the bitumen fed was recovered as a liquid product, and the spent sand contained less than 1% coke. The liquid product recovery system, by design, yielded three liquid streams with distinctly different properties.

  8. An experimental study of the hydrodynamics and cluster formation in a circulating fluidized bed. Topical report, January 1, 1991--June 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, M.; Jurewicz, J.; Heping, Y.; Clifton, K.

    1992-07-01

    This research program involves two major aspects. First, to evaluate techniques to effectively probe the polydisperse gas-solid flows and second, to apply these techniques to study the gas-solid flow structure and clusters in the riser of a circulating fluidized bed riser. Amongst the non-intrusive techniques a modified laser Doppler technique based on the fluorescence-emission concept has been adopted and the other techniques involve pitot-static pressure probes. A circulating fluidized bed (CFB) facility has been designed, built and is currently operational at West Virginia University. The design provides for maximum versatility in investigating the hydrodynamics of the CFB riser. Two stage cyclones are employed to capture the particles exhausted from the riser. Measurements of gas velocity distribution were carried out in the circulating fluidized bed riser. with particles having a mean diameter of 112 {mu}m and a density of 2305 kg/m{sup 3} and another set of particles with a mean diameter of 145 {mu}m and a density of 2245 kg/m{sup 3}. The experimental results showed that the local gas velocity varied with the radial position, elevation, solids circulation rate, superficial velocity and particle size. A general formula for gas velocity distribution in the circulating fluidized bed riser was obtained based on the particle circulation, superficial velocity and particle diameter. The pressure drops across the L-valve were also studied for different particle sizes, L-valve diameters and aeration. The solids flowrate was found to be a function of the L-valve geometry, operating parameters and solids properties. Pressure drop of L-valve increases with increasing solids diameter and decreasing diameter of the L-valve. Pressure drop across standpipe increases as the solids diameter and diameter of the standpipe decrease.

  9. Pressure ulcer risk factors in persons with spinal cord injury part 2: the chronic stage.

    Science.gov (United States)

    Gélis, A; Dupeyron, A; Legros, P; Benaïm, C; Pelissier, J; Fattal, C

    2009-09-01

    Pressure ulcers (PUs) are a common complication following spinal cord injury (SCI). Prevalence for persons in the chronic SCI stage varies between 15 and 30%. The risk assessment scales used nowadays were designed on pathophysiological concepts and are not SCI-specific. Recently, an epidemiological approach to PU risk factors has been proposed for designing an SCI-specific assessment tool. The first results seem quite disappointing, probably because of the level of evidence of the risk factors used. To determine PU risk factors correlated to the chronic stage of SCI. Systematic review of the literature. There are several PU risk factors for chronic SCI stage: socio-demographics, neurological, medical or behavioral. The level of evidence varies: it is quite high for the socio-demographics and neurological factors and low for behavioral factors. Behavioral risk factors (relieving the pressure, careful skin monitoring, smoking) are probably the ones for which a preventive strategy can be established. It is important to develop specific assessment tools for these behavioral risk factors to determine their relevance and evaluate the effect of therapeutic educational programs on persons with SCI.

  10. Distributor effects near the bottom region of turbulent fluidized beds

    OpenAIRE

    Sobrino Fernández, Celia; Ellis, Noko; Vega Blázquez, Mercedes de

    2009-01-01

    The distributor plate effects on the hydrodynamic characteristics of turbulent fluidized beds are investigated by obtaining measurements of pressure and radial voidage profiles in a column diameter of 0.29 m with Group A particles using bubble bubble-cap or perforated plate distributors. Distributor pressure drop measurements between the two distributors are compared with the theoretical estimations while the influence of the mass inventory is studied. Comparison is established fo...

  11. Fluidized bed combustion: mixing and pollutant limitation

    Energy Technology Data Exchange (ETDEWEB)

    Leckner, B. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy Conversion

    1997-10-01

    Fluidized bed combustion (FBC) has been applied commercially during a few decades, and sufficient knowledge is gained to design boilers with sizes of up to several hundreds of megawatt thermal power (MW{sub th}). The knowledge of what goes on inside a large combustion chamber is still limited, however, and this impedes further optimization and efficient solution of problems that might occur. Despite this lack of knowledge the present survey deals with combustion chamber processes and discusses mixing and distribution of fuel and air in the combustion chamber and its importance for sulphur capture and reduction of emissions of nitrogen oxides. It is desirable to present the material in a general way and to cover the entire field of FBC. However, the scarce openly published information deals mostly with coal combustion in atmospheric circulating fluidized bed (CFB) combustors, and therefore this application will receive most attention, but reference is also made to pressurized combustion and to other fuels than coal. In this context the important work made in the LIEKKI project on the analysis of different fuels and on the influence of pressure should be especially pointed out. (orig.)

  12. Analysis of fatigue reliability for high temperature and high pressure multi-stage decompression control valve

    Science.gov (United States)

    Yu, Long; Xu, Juanjuan; Zhang, Lifang; Xu, Xiaogang

    2018-03-01

    Based on stress-strength interference theory to establish the reliability mathematical model for high temperature and high pressure multi-stage decompression control valve (HMDCV), and introduced to the temperature correction coefficient for revising material fatigue limit at high temperature. Reliability of key dangerous components and fatigue sensitivity curve of each component are calculated and analyzed by the means, which are analyzed the fatigue life of control valve and combined with reliability theory of control valve model. The impact proportion of each component on the control valve system fatigue failure was obtained. The results is shown that temperature correction factor makes the theoretical calculations of reliability more accurate, prediction life expectancy of main pressure parts accords with the technical requirements, and valve body and the sleeve have obvious influence on control system reliability, the stress concentration in key part of control valve can be reduced in the design process by improving structure.

  13. Effect of pressure relaxation during the laser heating and electron-ion relaxation stages

    Energy Technology Data Exchange (ETDEWEB)

    Chimier, B.; Tikhonchuk, V.T.; Hallo, L. [Univ Bordeaux 1, CEA, CNRS, CELIA, UMR 5107, 33 - Talence (France)

    2008-09-15

    The multi-phase equation of state by Bushman et al. (Sov. Tech. Rev. 5:1-44, 2008) is modified to describe states with different electron and ion temperatures and it is applied to the non-equilibrium evolution of an aluminum sample heated by a subpicosecond laser pulse. The sample evolution is described by the two-temperature model for the electron and ion temperatures, while the pressure and density are described by a simplified relaxation equation. The pressure relaxation in the heating stage reduces the binding energy and facilitates the electron-driven ablation. The model is applied to estimate the ablation depth of an Al target irradiated by a subpicosecond laser pulse. It improves the agreement with the experimental data and provides a new explanation of the ablation process. (authors)

  14. The Optimization of Four-Stage Low Pressure Turbine with Outlet Guide Vane

    Science.gov (United States)

    Matveev, V.; Baturin, O.; Popov, G.

    2018-01-01

    The goal of the research was to improve efficiency of four-stage low-pressure turbine with outlet guide vane (LPT) at the design point by optimization the shape of all turbine stator vanes and the stagger angles of all rotor blades. The LPT mathematical model was created by using NUMECA FineTurbo software. Several constraints were imposed the mass flow rate through the LPT and the total pressure ratio at the design point may vary within ±0.5% from the original. Parameters of the stator blade shape and rotor blades stagger angles were obtained. This new geometry of the LPT blades produce a 0.8% increase in efficiency at the design point.

  15. Treatment of Early-Stage Pressure Ulcers by Using Autologous Adipose Tissue Grafts

    Directory of Open Access Journals (Sweden)

    Giovanni Francesco Marangi

    2014-01-01

    Full Text Available Assessing pressure ulcers (PUs in early stages allows patients to receive safer treatment. Up to now, in addition to clinical evaluation, ultrasonography seems to be the most suitable technique to achieve this goal. Several treatments are applied to prevent ulcer progression but none of them is totally effective. Furthermore, the in-depth knowledge of fat regenerative properties has led to a wide use of it. With this study the authors aim at introducing a new approach to cure and prevent the worsening of early-stage PUs by using fat grafts. The authors selected 42 patients who showed clinical and ultrasonographic evidence of early-stage PUs. Values of skin thickness, fascial integrity, and subcutaneous vascularity were recorded both on the PU area and the healthy trochanteric one, used as control region. Fat grafting was performed on all patients. At three months, abnormal ultrasonographic findings, such as reduction of cutaneous and subcutaneous thickness, discontinuous fascia, and decrease in subcutaneous vascularity, all were modified with respect to almost all the corresponding parameters of the control region. Results highlight that the use of fat grafts proved to be an effective treatment for early-stage PUs, especially in the care of neurological and chronic bedridden patients.

  16. Treatment of early-stage pressure ulcers by using autologous adipose tissue grafts.

    Science.gov (United States)

    Marangi, Giovanni Francesco; Pallara, Tiziano; Cagli, Barbara; Schena, Emiliano; Giurazza, Francesco; Faiella, Elio; Zobel, Bruno Beomonte; Persichetti, Paolo

    2014-01-01

    Assessing pressure ulcers (PUs) in early stages allows patients to receive safer treatment. Up to now, in addition to clinical evaluation, ultrasonography seems to be the most suitable technique to achieve this goal. Several treatments are applied to prevent ulcer progression but none of them is totally effective. Furthermore, the in-depth knowledge of fat regenerative properties has led to a wide use of it. With this study the authors aim at introducing a new approach to cure and prevent the worsening of early-stage PUs by using fat grafts. The authors selected 42 patients who showed clinical and ultrasonographic evidence of early-stage PUs. Values of skin thickness, fascial integrity, and subcutaneous vascularity were recorded both on the PU area and the healthy trochanteric one, used as control region. Fat grafting was performed on all patients. At three months, abnormal ultrasonographic findings, such as reduction of cutaneous and subcutaneous thickness, discontinuous fascia, and decrease in subcutaneous vascularity, all were modified with respect to almost all the corresponding parameters of the control region. Results highlight that the use of fat grafts proved to be an effective treatment for early-stage PUs, especially in the care of neurological and chronic bedridden patients.

  17. Staged, High-Pressure Oxy-Combustion Technology: Development and Scale-Up

    Energy Technology Data Exchange (ETDEWEB)

    Axelbaum, Richard [Washington Univ., St. Louis, MO (United States); Kumfer, Benjamin [Washington Univ., St. Louis, MO (United States); Gopan, Akshay [Washington Univ., St. Louis, MO (United States); Yang, Zhiwei [Washington Univ., St. Louis, MO (United States); Phillips, Jeff [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); Pint, Bruce [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-12-29

    The immediate need for a high efficiency, low cost carbon capture process has prompted the recent development of pressurized oxy-combustion. With a greater combustion pressure the dew point of the flue gas is increased, allowing for effective integration of the latent heat of flue gas moisture into the Rankine cycle. This increases the net plant efficiency and reduces costs. A novel, transformational process, named Staged, Pressurized Oxy-Combustion (SPOC), achieves additional step changes in efficiency and cost reduction by significantly reducing the recycle of flue gas. The research and development activities conducted under Phases I and II of this project (FE0009702) include: SPOC power plant cost and performance modeling, CFD-assisted design of pressurized SPOC boilers, theoretical analysis of radiant heat transfer and ash deposition, boiler materials corrosion testing, construction of a 100 kWth POC test facility, and experimental testing. The results of this project have advanced the technology readiness level (TRL) of the SPOC technology from 1 to 5.

  18. Multi-stage versus single-stage inflation and deflation cycle for alternating low pressure air mattresses to prevent pressure ulcers in hospitalised patients: a randomised-controlled clinical trial.

    Science.gov (United States)

    Demarré, L; Beeckman, D; Vanderwee, K; Defloor, T; Grypdonck, M; Verhaeghe, S

    2012-04-01

    The duration and the amount of pressure and shear must be reduced in order to minimize the risk of pressure ulcer development. Alternating low pressure air mattresses with multi-stage inflation and deflation cycle of the air cells have been developed to relieve pressure by sequentially inflating and deflating the air cells. Evidence about the effectiveness of this type of mattress in clinical practice is lacking. This study aimed to compare the effectiveness of an alternating low pressure air mattress that has a standard single-stage inflation and deflation cycle of the air cells with an alternating low pressure air mattress with multi-stage inflation and deflation cycle of the air cells. A randomised controlled trial was performed in a convenience sample of 25 wards in five hospitals in Belgium. In total, 610 patients were included and randomly assigned to the experimental group (n=298) or the control group (n=312). In the experimental group, patients were allocated to an alternating low pressure air mattress with multi-stage inflation and deflation cycle of the air cells. In the control group, patients were allocated to an alternating low pressure air mattress with a standard single-stage inflation and deflation cycle of the air cells. The outcome was defined as cumulative pressure ulcer incidence (Grade II-IV). An intention-to-treat analysis was performed. There was no significant difference in cumulative pressure ulcer incidence (Grade II-IV) between both groups (Exp.=5.7%, Contr.=5.8%, p=0.97). When patients developed a pressure ulcer, the median time was 5.0 days in the experimental group (IQR=3.0-8.5) and 8.0 days in the control group (IQR=3.0-8.5) (Mann-Whitney U-test=113, p=0.182). The probability to remain pressure ulcer free during the observation period in this trial did not differ significantly between the experimental group and the control group (log-rank χ(2)=0.013, df=1, p=0.911). An alternating low pressure air mattress with multi-stage inflation

  19. Minimum slugging velocity in fluidized beds containing vertical rods

    Energy Technology Data Exchange (ETDEWEB)

    Coronella, C.J.; Lee, S.Y.; Seader, J.D. (University of Utah, Salt Lake City, UT (United States). Dept. of Chemical Engineering)

    1994-09-01

    A new method for determining the onset of slugging in fluidized beds is presented. Pressure-drop fluctuations, measured from below the distributor to the gas exit line, are transformed to the frequency domain by the power spectral desity function (PSDF). The dominant frequency of the PSDF corresponds to the eruption frequency of bubbles or slugs. A fluidized bed is in the slugging regime when this dominant frequency, f[sub d], remains constant with changing gas velocity. This method is an improvement over previous methods because of the simple nature of the apparatus required, and because it is possible to locate the pressure probes so that they do not interfere with the fluidization or undergo rapid wear from the constant particle movement. This method was used to determine the gas velocity corresponding to the transition from the bubbling to the slugging regime for a 10cm diameter bed of sand fluidized with air and containing three 1.9cm diameter vertical rods at 5.2cm centre-to-centre triangular spacing and extending the length of the bed, and to compare the results with those from the same bed without any internal rods. The presence of the vertical rods inhibited the onset of the slugging regime, and significantly extended the bubbling regime to higher gas velocities. 32 refs., 12 figs.

  20. Staged, High-Pressure Oxy-Combustion Technology: Development and Scale-Up

    Energy Technology Data Exchange (ETDEWEB)

    Axelbaum, Richard; Xia, Fei; Gopan, Akshay; Kumfer, Benjamin

    2014-09-30

    Washington University in St. Louis and its project partners are developing a unique pressurized oxy-combustion process that aims to improve efficiency and costs by reducing the recycling of flue gas to near zero. Normally, in the absence of recycled flue gas or another inert gas, combustion of fuel and oxygen results in a dramatic increase in temperature of the combustion products and radiant energy, as compared to combustion in air. High heat flux to the boiler tubes may result in a tube surface temperatures that exceed safe operating limits. In the Staged Pressurized Oxy-Combustion (SPOC) process, this problem is addressed by staging the delivery of fuel and by novel combustion design that allows control of heat flux. In addition, the main mode of heat transfer to the steam cycle is by radiation, as opposed to convection. Therefore, the requirement for recycling large amounts of flue gas, for temperature control or to improve convective heat transfer, is eliminated, resulting in a reduction in auxiliary loads. The following report contains a detailed summary of scientific findings and accomplishments for the period of Oct. 1, 2013 to Sept 30, 2014. Results of ASPEN process and CFD modelling activities aimed at improving the SPOC process and boiler design are presented. The effects of combustion pressure and fuel moisture on the plant efficiency are discussed. Combustor pressure is found to have only a minor impact beyond 16 bar. For fuels with moisture content greater than approx 30%, e.g. coal/water slurries, the amount of latent heat of condensation exceeds that which can be utilized in the steam cycle and plant efficiency is reduced significantly. An improved boiler design is presented that achieves a more uniform heat flux profile. In addition, a fundamental study of radiation in high-temperature, high-pressure, particle-laden flows is summarized which provides a more complete understanding of heat transfer in these unusual conditions and to allow for

  1. 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.

  2. Reproducibility of proximal and distal transcutaneous oxygen pressure measurements during exercise in stage 2 arterial claudication.

    Science.gov (United States)

    Bouyé, P; Picquet, J; Jaquinandi, V; Enon, B; Leftheriotis, G; Saumet, J-L; Abraham, P

    2004-06-01

    Although transcutaneous oxygen pressure measurements (tcpO2) are largely used in the investigation of vascular patients, its reproducibility is still debated. Indeed an unpredictable gradient exists between arterial and transcutaneous oxygen pressure. We hypothesised that indices taking into account changes over time and independent of absolute starting values would be more reproducible than other indices. comparative test-retest procedure (1 to 13 days between tests). institutional practice, ambulatory care. 15 subjects with stage 2 claudication. tcpO2 recordings at rest and at exercise during the 2 treadmill tests. calculation of the Delta-from-rest of oxygen pressure index (limb tcpO2 changes minus chest tcpO2 changes), of the resting - or minimal values attained during exercise - of absolute tcpO2 and of the regional perfusion index (regional perfusion index: ration of limb to chest). Both absolute tcpO2 and regional perfusion index at rest showed low reproducibility. During exercise the best reproducibility was attained through Delta-from-rest of oxygen pressure index calculation. Equations from the linear regression analysis (test 2 versus test 1) were 0.88 x -4.2 (r(2)=0.82) at the buttock level and 0.82 x -3.8 (r(2)=0.80) at the calf level. TcpO2 measurement on the calf or buttock during exercise, is a reproducible measurement in patients with vascular claudication, specifically when corrected for exercise-induced systemic pO2 changes trough Delta-from-rest of oxygen pressure calculation.

  3. Multidimensionality in fluidized nanopowder agglomerates

    Science.gov (United States)

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

    2013-06-01

    In recent years, the interest in fluidization as a mean to process nanoparticles is strongly increasing. Due to the small size of the nanoparticles, which makes van der Waals forces predominate, they do not fluidize as single particles but as agglomerates. Various researchers using settling experiments and bed expansion measurements conclude that fluidized agglomerates are fractal structures with a single fractal dimension of 2.5. Based on microscopy results, Wang et al. ``Powder Technology 124, 152-C159 (2002)'' propose a hierarchical structure, which seems in contradiction with the use of only one fractal dimension as a descriptor of the whole structure. Moreover, it is not clear whether the structure presented by the agglomerates ex-situ is the same during fluidization. Hence, in this work we have characterized in-situ the internal structure of fluidized agglomerates by means of spin-echo small-angle neutron scattering (SESANS). We show that the structure of the agglomerates present at least two fractal dimensions. One of them is ~= 2.1 and characterizes the primary strong agglomerates. The second one is ~= 2.8 and characterizes the larger agglomerates formed by the primary agglomerates.

  4. The relationship of fluidized bed technology to the U.S. Clean Coal Technology demonstration program

    International Nuclear Information System (INIS)

    Weth, G.; Geffken, J.; Huber, D.A.

    1991-01-01

    Fluidized Bed Combustion projects (both AFBCs and PFBCs) have a prominent role in the US DOE Clean Coal Technology (CCT) Program. This program has the successful commercialization of these technologies as its primary objective and this is the basic criterion for government funding and participation in the development and demonstration of the technologies. Under the CCT program the US DOE is actively involved in the development and operation of three Fluidized Bed Technology projects, NUCLA, TIDD, and SPORN, and is in the negotiation stage on others, Dairyland, Nichols and Tallahassee. All of these projects, along with the operating information on fluidized beds in the industrial sector, will provide a basis for evaluating future utilization of Fluidized Bed Technology in the market place. Impacting upon further utilization will be the time-frame and the Clean Air Act Amendments of 1990. This paper presents the results of a study to ascertain the commercial readiness of Fluidized Bed Technology to meet the emissions and time-frame requirements of the Clean Air Act Amendments of 1990. Specifically addressed are: Commercialization criteria/factors which candidate and/or existing CCTs must achieve in order to gain market acceptance. The status of Fluidized Bed Technology in achieving these commercialization criteria for market acceptance (industrial and utility) consistent with the time frame of the Clean Air Act Amendments of 1990. Recommendations of commercialization criteria for future fluidized bed CCT demonstration projects

  5. Apparatus and process for controlling fluidized beds

    Science.gov (United States)

    Rehmat, Amirali G.; Patel, Jitendra G.

    1985-10-01

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

  6. The effect of homogenization pressure and stages on the amounts of Lactic and Acetic acids of probiotic yoghurt

    Directory of Open Access Journals (Sweden)

    R Massoud

    2014-12-01

    Full Text Available Nowadays the use of probiotic products especially yogurt, due to having wonderful and health properties, has become popular in the world. In this study, the effect of homogenization pressure (100, 150 and 200 bars and stage (single and two on the amount of lactic and acetic acids was investigated. Yoghurts were manufactured from low-fat milk treated using high pressure homogenization at 100,150 and 200 bar and at 60°C. The amount of lactic and acetic acids was determined after the days 1, 7, 14 and 21 of storage at 4ºC. The experiments were set up using a completely randomized design. With the increase of pressure and stage of homogenization, the amount of both acids was increased (p<0.01. The greatest amount of lactic and acetic acids during the storage period was observed in the sample homogenized at a pressure of 200 bars and two stages.

  7. Association of "Elevated Blood Pressure" and "Stage 1 Hypertension" With Cardiovascular Mortality Among an Asian Population.

    Science.gov (United States)

    Talaei, Mohammad; Hosseini, Naeimeh; Koh, Angela S; Yuan, Jian-Min; Koh, Woon-Puay

    2018-04-10

    The new American College of Cardiology/American Heart Association high blood pressure (BP) guidelines in the United States have lowered definition of hypertension by defining normal as systolic/diastolic BP hypertension as systolic between 130 and 139 mm Hg or diastolic between 80 and 89 mm Hg. We investigated the association between the new hypertension definition and cardiovascular disease mortality among Chinese in Singapore. We used data from 30 636 participants of a population-based cohort, the SCHS (Singapore Chinese Health Study), who had BPs measured using a standard protocol at ages 46 to 85 years between 1994 and 2005. Information on lifestyle factors was collected at recruitment (1993-1998) and follow-up 1 interviews (1999 and 2004). Mortality was identified via nationwide registry linkage up to December 31, 2016. Neither elevated BP (hazard ratio, 0.89; 95% confidence interval, 0.74-1.07) nor stage 1 hypertension (hazard ratio, 0.94; 95% confidence interval, 0.81-1.11) was associated with increased risk of cardiovascular mortality compared with normal BP in the whole cohort. Stage 1 hypertension was associated with increased cardiovascular risk only in those hypertension may not be associated with increased cardiovascular mortality across all ages among Chinese in Singapore, but that the at-risk subpopulation is limited to those <65 years of age and without a prior cardiovascular disease. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  8. IEN project - Fluidized bed burner

    International Nuclear Information System (INIS)

    1985-08-01

    Due to difficulties inherent to the organic waste storage from laboratories and institutes which use radioactive materials for scientific researches, the Nuclear Facilities Division (DIN/CNEN); elaborated a project for constructing a fluidized burner, in laboratory scale, for burning the low level organic radioactive wastes. The burning system of organic wastes is described. (M.C.K.) [pt

  9. Fluidization of Dried Wastewater Sludge.

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Pohořelý, Michael; Trnka, Otakar

    2007-01-01

    Roč. 178, 3 (2007) , s. 166-172 ISSN 0032-5910 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidization characteristics * multiphase reactors * dried stabilized wastewater sludge Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.130, year: 2007

  10. Instability and the formation of bubbles and the plugs in fluidized beds

    Directory of Open Access Journals (Sweden)

    Piotr Schulz

    2004-01-01

    Full Text Available This is an review paper, particulary concentrate on results not many researches by reason that are explain in the text. We consider stability of disperse, two-phase flow (gas-solid particles or liquid-solid particles linear and non-linear. In particular we discuss the result of Anderson, Sundareson and Jackson (1995 [Anderson K., Sundareson S., Jackson R.: Instabilities and the formation of bubbles in fluidized beds. J. Fluid Mech. 303 (1995, 327-366] that for vertical dispersion flow one- and two-dimensional, they attack problem growing disturbances directly by numerical integration of equations of motion from given initial conditions (using computer Cray C-90. In principle, this would allow authors to explore all aspects of dynamical behaviour of fluidized beds. It is interesting mechanism of periodic plug describing by Anderson et al. and attest by other researchers. Second part of paper is more general, dedicate the problem of linear stability of uniformly fluidized state ("fluidized bed". We make the most important stages of calculations (after to Jackson (2000 [Jackson R.: The Dynamics of Fluidized Particles. Cambridge University Press 2000] and demonstrate that the majority (but not all of fluidized beds with parameters having technical importance is unstable, or stable in narrow interval of wave numbers \\(k\\.

  11. Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition.

    Science.gov (United States)

    Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

    2015-07-01

    A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

  12. Pulverized coal vs. circulating fluidized bed: An economic comparison

    International Nuclear Information System (INIS)

    Johns, R.F.

    1991-01-01

    As the power industry looks to the 1990s for expanded steam generation capacity, boiler owners will continue on their long-standing assignment to evaluate and select the best, lowest cost alternative to meet their energy needs. For coal-fired plants, this evaluation process includes pulverized coal-fired boilers (PC) and circulating fluidized bed boilers (CFB). The cost difference between these products is site specific and depends on several variables, including: Boiler size, pressure, and temperature; Operating variables, such as the cost for fuel, auxiliary power, SO 2 reagent, and ash disposal; Capital cost; and Financial variables, such as evaluation period and interest rate. This paper provides a technical and economic comparison between a pulverized coal-fired boiler and circulating fluidized bed boiler

  13. Nitrogen Chemistry in Fluidized Bed Combustion of Coal

    DEFF Research Database (Denmark)

    Jensen, Anker Degn

    The present Ph.D thesis describes an experimental and theoretical investigation of the formation and destruction of nitrogen oxides (NOx and N2O) in fluidized bed combustion (FBC) of coal. A review of the current knowledge of nitrogen chemistry in FBC is presented. The review covers both laboratory...... for the emission of NOx from FBC has been developed as part of a JOULE project. The model is based on the two-phase theory of fluidization for the bed with a Kunii-Levenspiel type freeboard model and includes submodels for coal devolatilization, combustion of volatiles and char and a detailed model of NO formation...... and reduction by homogeneous and heterogeneous reactions. The data for the estimation of kinetics of the heterogeneous reactions were measured by one of the partners in the project for char and bed material sampled from a pressurized FBC pilot plant burning Kiveton Park coal. Experimental data from the pilot...

  14. Nebivolol reduces central blood pressure in stage I hypertensive patients: experimental single cohort study

    Directory of Open Access Journals (Sweden)

    Renan Oliveira Vaz-de-Melo

    Full Text Available CONTEXT AND OBJECTIVES: Assessment of central blood pressure (BP has grown substantially over recent years because evidence has shown that central BP is more relevant to cardiovascular outcomes than peripheral BP. Thus, different classes of antihypertensive drugs have different effects on central BP despite similar reductions in brachial BP. The aim of this study was to investigate the effect of nebivolol, a β-blocker with vasodilator properties, on the biochemical and hemodynamic parameters of hypertensive patients.DESIGN AND SETTING: Experimental single cohort study conducted in the outpatient clinic of a university hospital.METHODS: Twenty-six patients were recruited. All of them underwent biochemical and hemodynamic evaluation (BP, heart rate (HR, central BP and augmentation index before and after 3 months of using nebivolol.RESULTS: 88.5% of the patients were male; their mean age was 49.7 ± 9.3 years and most of them were overweight (29.6 ± 3.1 kg/m2 with large abdominal waist (102.1 ± 7.2 cm. There were significant decreases in peripheral systolic BP (P = 0.0020, diastolic BP (P = 0.0049, HR (P < 0.0001 and central BP (129.9 ± 12.3 versus 122.3 ± 10.3 mmHg; P = 0.0083 after treatment, in comparison with the baseline values. There was no statistical difference in the augmentation index or in the biochemical parameters, from before to after the treatment.CONCLUSIONS: Nebivolol use seems to be associated with significant reduction of central BP in stage I hypertensive patients, in addition to reductions in brachial systolic and diastolic BP.

  15. Flue Gas Emissions from Fluidized Bed Combustion

    NARCIS (Netherlands)

    Bramer, E.A.; Valk, M.

    1995-01-01

    During the past decades fluidized bed coal combustion was developed as a technology for burning coal in an effective way meeting the standards for pollution control. During the earlier years of research on fluidized bed combustion, the potential for limiting the S02 emission by adding limestone to

  16. Investigation of flow mechanisms in conical models of fluidized beds and transfer of the results to high-temperature-coating beds. A study on the coating of nuclear fuel particles in fluidized beds

    International Nuclear Information System (INIS)

    Kalthoff, B.; Gyarmati, E.; Nickel, H.

    The different states of movement of the fluid-solid particle system as occurring in coating of nuclear particle fuel in conical fluidized beds determine the transfer of momentum, heat and mass in the fluidized bed. To know the flow characteristics, therefore, is essential for the understanding of the complex processes which take place during coating. As experimental studies in actual coaters initially were impossible due to the high temperature levels of up to 2000 0 C, information on characteristic behavior of the fluidized bed was obtained from geometrically similar model beds. Based on principles in the mechanics of similarity the fluid-solid particle system was selected. Hence, results obtained in model tests could be correlated to hot fluidized beds by means of a dimensionless characteristic number describing the fluid-solid system. A second combination of characteristic numbers allows the characterization of the three states of a fluidizing regime, i.e., spouting, bubbling, and slugging. For examining the model test results in hot beds, a measuring device was developed applicable to both cold model beds and actual fluidized bed coaters; pressure oscillations originating in the beds could be made visible by means of electronics and their frequency measured. Coating experiments with different batches and at different temperature levels rendered this frequency to decrease with increase in bed height. Thus the frequency is an important index for the momentary state of fluidization of the fluid-solid particle system. (U.S.)

  17. Research of fluidized bed cement clinker sintering system by pilot plant; Ryudosho cement shosei gijutsu no kaihatsu. 7

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, T. [Center for Coal Utilization, Japan, Tokyo (Japan); Sato, N.; Hashimoto, I.; Nakatsuka, M. [The Cement Association of Japan, Tokyo (Japan)

    1996-09-01

    While a cement manufacturing process generally performs sintering by using a rotary kiln, a development work has been carried out as a subsidy operation of the Agency of Natural Resources and Energy on a cement sintering technology using a fluidized bed consisted of two furnaces: a jet flow bed granulating furnace and a fluidized bed sintering furnace. This paper reports the results of tests and researches performed during fiscal 1995. A plant with a scale of 20 ton-a-day production started in 1993 after having gone through bench scale tests. The year 1995 conducted by August its performance evaluation, review of the operation method and the safety criteria, and generalization of the tests. A multi-stage cyclone system has been employed in the preheating equipment for cement material powder. A number of improvements have been realized in the aspects of construction and operation, such as stabilization of dust collecting efficiency by employing a high-efficiency type cyclone, and operation with reduced pressure variation. Based on these results, a construction had been progressed in parallel on a new plant upscaled to 200 ton-a-day production. The new plant was completed in December, 1995. 9 figs., 8 tabs.

  18. Fluidized bed silicon deposition from silane

    Science.gov (United States)

    Hsu, George (Inventor); Levin, Harry (Inventor); Hogle, Richard A. (Inventor); Praturi, Ananda (Inventor); Lutwack, Ralph (Inventor)

    1984-01-01

    A process and apparatus for thermally decomposing silicon containing gas for deposition on fluidized nucleating silicon seed particles is disclosed. Silicon seed particles are produced in a secondary fluidized reactor by thermal decomposition of a silicon containing gas. The thermally produced silicon seed particles are then introduced into a primary fluidized bed reactor to form a fludized bed. Silicon containing gas is introduced into the primary reactor where it is thermally decomposed and deposited on the fluidized silicon seed particles. Silicon seed particles having the desired amount of thermally decomposed silicon product thereon are removed from the primary fluidized reactor as ultra pure silicon product. An apparatus for carrying out this process is also disclosed.

  19. Continuous austempering fluidized bed furnace. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.N. [Lamar Univ., Beaumont, TX (United States). Dept. of Mechanical Engineering

    1997-09-23

    The intended objective of this project was to show the benefits of using a fluidized bed furnace for austenitizing and austempering of steel castings in a continuous manner. The division of responsibilities was as follows: (1) design of the fluidized bed furnace--Kemp Development Corporation; (2) fabrication of the fluidized bed furnace--Quality Electric Steel, Inc.; (3) procedure for austempering of steel castings, analysis of the results after austempering--Texas A and M University (Texas Engineering Experiment Station). The Department of Energy provided funding to Texas A and M University and Kemp Development Corporation. The responsibility of Quality Electric Steel was to fabricate the fluidized bed, make test castings and perform austempering of the steel castings in the fluidized bed, at their own expense. The project goals had to be reviewed several times due to financial constraints and technical difficulties encountered during the course of the project. The modifications made and the associated events are listed in chronological order.

  20. The optimum intermediate pressure of two-stages vapor compression refrigeration cycle for Air-Conditioning unit

    Science.gov (United States)

    Ambarita, H.; Sihombing, H. V.

    2018-03-01

    Vapor compression cycle is mainly employed as a refrigeration cycle in the Air-Conditioning (AC) unit. In order to save energy, the Coefficient of Performance (COP) of the need to be improved. One of the potential solutions is to modify the system into multi-stages vapor compression cycle. The suitable intermediate pressure between the high and low pressures is one of the design issues. The present work deals with the investigation of an optimum intermediate pressure of two-stages vapor compression refrigeration cycle. Typical vapor compression cycle that is used in AC unit is taken into consideration. The used refrigerants are R134a. The governing equations have been developed for the systems. An inhouse program has been developed to solve the problem. COP, mass flow rate of the refrigerant and compressor power as a function of intermediate pressure are plotted. It was shown that there exists an optimum intermediate pressure for maximum COP. For refrigerant R134a, the proposed correlations need to be revised.

  1. Fundal pressure versus controlled cord traction as part of the active management of the third stage of labour.

    Science.gov (United States)

    Peña-Martí, G; Comunián-Carrasco, G

    2007-10-17

    There are two basic interventions to help to deliver the placenta as part of the active management of the third stage of labour: (1) fundal pressure, and (2) controlled traction on the umbilical cord. Both of these methods may, in addition, have adverse outcomes. Fundal pressure may interrupt the process of placental detachment and cause pain, haemorrhage or uterine inversion, and controlled cord traction, if undertaken before placental separation or without prior administration of a uterotonic drug, may have similar adverse effects. The obstetric clinical practice on this issue is not standardised. To determine the efficacy of fundal pressure versus controlled cord traction as part of the active management of the third stage of labour. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 2), MEDLINE (January 1966 to April 2006), EMBASE (January 1988 to April 2006) and LILACS (1982 to April 2006). We searched for published and unpublished randomised and quasi-randomised controlled trials. Two review authors independently identified potential studies from the literature search and assessed them for methodological quality and appropriateness of inclusion. The search strategies yielded five studies for consideration of inclusion. However, none of these studies fulfilled the requirements for inclusion in this review. We identified no randomised controlled trials comparing the efficacy of fundal pressure versus controlled cord traction as part of the active management of the third stage of labour. Hence controlled cord traction, after awaiting signs of placental separation, should remain the third component of the active management of third stage of labour, and follow the routine administration of a uterotonic drug and cord clamping.

  2. 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.

  3. 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....

  4. 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.

  5. Fluidization calculation on nuclear fuel kernel coating

    International Nuclear Information System (INIS)

    Sukarsono; Wardaya; Indra-Suryawan

    1996-01-01

    The fluidization of nuclear fuel kernel coating was calculated. The bottom of the reactor was in the from of cone on top of the cone there was a cylinder, the diameter of the cylinder for fluidization was 2 cm and at the upper part of the cylinder was 3 cm. Fluidization took place in the cone and the first cylinder. The maximum and the minimum velocity of the gas of varied kernel diameter, the porosity and bed height of varied stream gas velocity were calculated. The calculation was done by basic program

  6. Exploratory and basic fluidized-bed combustion studies. Quarterly report, January-March 1980

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, I.; Myles, K.M.; Swift, W.M.

    1980-12-01

    This work supports development studies for both atmospheric and pressurized fluidized-bed coal combustion. Laboratory and process development studies are aimed at providing needed information on limestone utilization, removal of particulates and alkali metal compounds from the flue gas, control of SO/sub 2/ and trace pollutants emissions, and other aspects of fluidized-bed combustion. This report presents information on: (1) the development of a limestone utilization predictive methodology, (2) studies of particle breakup and elutriation, (3) basic studies on limestone sulfation enhancement by hydration, (4) studies of the kinetics of the hydration process, and (5) an investigation of various hydration process concepts.

  7. Model-free adaptive control of supercritical circulating fluidized-bed boilers

    Science.gov (United States)

    Cheng, George Shu-Xing; Mulkey, Steven L

    2014-12-16

    A novel 3-Input-3-Output (3.times.3) Fuel-Air Ratio Model-Free Adaptive (MFA) controller is introduced, which can effectively control key process variables including Bed Temperature, Excess O2, and Furnace Negative Pressure of combustion processes of advanced boilers. A novel 7-input-7-output (7.times.7) MFA control system is also described for controlling a combined 3-Input-3-Output (3.times.3) process of Boiler-Turbine-Generator (BTG) units and a 5.times.5 CFB combustion process of advanced boilers. Those boilers include Circulating Fluidized-Bed (CFB) Boilers and Once-Through Supercritical Circulating Fluidized-Bed (OTSC CFB) Boilers.

  8. Study of reactivity of fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Rammsy, J.E.M.

    1985-01-01

    The reactor physics calculations of a 19 module Fluidized Bed Nuclear Reactor using Leopard and Odog codes are performed. The behaviour of the reactor was studied by calculating the reactivity of the reactor as a function of the parameters governing the operational and accidental conditions of the reactor. The effects of temperature, pressure, and vapor generation in the core on the reactivity are calculated. Also the start up behaviour of the reactor is analyzed. For the purpose of the study of a prototype research reactor, the calculations on a one module reactor have been performed. (Author) [pt

  9. Single particle behaviour in circulating fluidized bed combustors

    DEFF Research Database (Denmark)

    Erik Weinell, Claus

    1994-01-01

    of fuel particles in a boiler. A cold pilot scale model of a circulating fluidized bed combustor was used. Here sand was recirculated by means of air. Pressure measurements along the riser determined suspension density. A radioactive tracking facility to determined the dynamic picture of the particle...... trajectories in the simulated boiler. In the splash zone, closest to the secondary air inlet an exponential decay in the solids suspension density with the riser height was observed. A transport zone was characterized by an exponential decay in the solids suspension but with a smaller decay constant...

  10. Simulation of energetic- and exergetic performance of microwave-assisted fluidized bed drying of soybeans

    International Nuclear Information System (INIS)

    Ranjbaran, M.; Zare, D.

    2013-01-01

    The performance of microwave-assisted fluidized bed drying of soybeans was simulated (using a previously validated mathematical model) and analyzed based on the first- and second law of thermodynamics. The energy and exergy analysis were carried out for several drying conditions. The effects of inlet air temperature, microwave power density, bed thickness and inlet air velocity on the efficiencies and inefficiencies of drying process have been simulated and discussed. Generally, application of microwave energy during fluidized bed drying enhanced the exergy efficiency of drying process. However, the results showed that it was more efficient not to apply microwave energy at the first stage of fluidized bed drying process. The application of higher levels of drying air temperature led in higher exergy efficiencies. The values of mean relative deviations for the predictions of efficiencies and inefficiencies of drying process were less than 14%, compared with those calculated using experimental data. - Highlights: • Introducing a mathematical model to predict the efficiency of microwave-assisted fluidized bed dryers. • Energy and exergy analysis in microwave-assisted fluidized bed drying of grains. • Providing practical recommendations for efficient use of microwave power during drying

  11. Metal wastage design guidelines for bubbling fluidized-bed combustors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lyczkowski, R.W.; Podolski, W.F.; Bouillard, J.X.; Folga, S.M. [Argonne National Lab., IL (United States)

    1992-11-01

    These metal wastage design guidelines identify relationships between metal wastage and (1) design parameters (such as tube size, tube spacing and pitch, tube bundle and fluidized-bed height to distributor, and heat exchanger tube material properties) and (2) operating parameters (such as fluidizing velocity, particle size, particle hardness, and angularity). The guidelines are of both a quantitative and qualitative nature. Simplified mechanistic models are described, which account for the essential hydrodynamics and metal wastage processes occurring in bubbling fluidized beds. The empirical correlational approach complements the use of these models in the development of these design guidelines. Data used for model and guideline validation are summarized and referenced. Sample calculations and recommended design procedures are included. The influences of dependent variables on metal wastage, such as solids velocity, bubble size, and in-bed pressure fluctuations, are discussed.

  12. COMPUTATIONAL MODELING OF CIRCULATING FLUIDIZED BED REACTORS

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Essam A

    2013-01-09

    Details of numerical simulations of two-phase gas-solid turbulent flow in the riser section of Circulating Fluidized Bed Reactor (CFBR) using Computational Fluid Dynamics (CFD) technique are reported. Two CFBR riser configurations are considered and modeled. Each of these two riser models consist of inlet, exit, connecting elbows and a main pipe. Both riser configurations are cylindrical and have the same diameter but differ in their inlet lengths and main pipe height to enable investigation of riser geometrical scaling effects. In addition, two types of solid particles are exploited in the solid phase of the two-phase gas-solid riser flow simulations to study the influence of solid loading ratio on flow patterns. The gaseous phase in the two-phase flow is represented by standard atmospheric air. The CFD-based FLUENT software is employed to obtain steady state and transient solutions for flow modulations in the riser. The physical dimensions, types and numbers of computation meshes, and solution methodology utilized in the present work are stated. Flow parameters, such as static and dynamic pressure, species velocity, and volume fractions are monitored and analyzed. The differences in the computational results between the two models, under steady and transient conditions, are compared, contrasted, and discussed.

  13. Hydrodynamic studies of the flow of fine particles through a fluidized dense bed of coarse solids

    Energy Technology Data Exchange (ETDEWEB)

    Talukdar, J.

    1993-12-31

    This study explains the hydrodynamics of a circulating fluidized bed (CFB) system, the Battelle Multi-Solids Fluidized Bed System (MSFB). It consists of a circulating fluidized bed of fine particles superimposed on a bubbling bed of coarse solids. One way to characterize such a system is to describe the mechanism of gas-solid flow through the bed. The gas flow in systems like these is through bubbles or slugs (regions of voids containing little or no solids). Bubbles are typically characterized by their size (length or diameter), their rise velocity, and their frequency. Another task of the initial phase of this study is to characterize an L-valve, a solids-recirculating device commonly used in an MSFB. Next, the mechanism of fine particle movement through a bubbling region of coarse fluidized solids is studied in considerable detail. Bubble characteristics are studied in a variety of systems of coarse particles with fines passing through at high velocity. Amongst numerous optical, electrical and other techniques available for the study of the passage of bubbles, the pressure fluctuation technique is the most robust. In this investigation, pressure probes are connected to pressure transducers which are in turn linked to an on-line data acquisition system supported on a microcomputer. A commercially available software package (Notebook) is used to sample pressure at specified points in the fluidized bed at extremely fast rates, of up to 200 Hz. This resulted in pressure-time traces which are analysed to give bubble length, bubble rise velocity, and bubble frequency. Another important objective of this study is to estimate the fine particle residence time in the dense bed section. A defluidization technique is utilized in experimentally measuring the solids holdup in the dense bed. A mathematical model is developed from first principles, based on a momentum balance on the fine particles.

  14. Fluidization technologies: Aerodynamic principles and process engineering.

    Science.gov (United States)

    Dixit, Rahul; Puthli, Shivanand

    2009-11-01

    The concept of fluidization has been adapted to different unit processes of pharmaceutical product development. Till date a lot of improvements have been made in the engineering design to achieve superior process performance. This review is focused on the fundamental principles of aerodynamics and hydrodynamics associated with the fluidization technologies. Fluid-bed coating, fluidized bed granulation, rotor processing, hot melt granulation, electrostatic coating, supercritical fluid based fluidized bed technology are highlighted. Developments in the design of processing equipments have been explicitly elucidated. This article also discusses processing problems from the operator's perspective along with latest developments in the application of these principles. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

  15. Lipid encapsulated phenolic compounds by fluidization

    Science.gov (United States)

    Phenolic compounds exhibit antioxidant and antimicrobial activities with applications as functional food and feed additives. Ferulic acid, a phenolic compound present in grain crops and lignocellulose biomass, was encapsulated with saturated triglycerides using a laboratory fluidizer. Stability of t...

  16. Longitudinal observations on circadian blood pressure variation in chronic kidney disease stages 3-5

    DEFF Research Database (Denmark)

    Elung-Jensen, T.; Strandgaard, S.; Kamper, Anne-Lise

    2008-01-01

    /non-dipper status prospectively in a study on dosage of enalapril in progressive chronic kidney disease (CKD) stages 3-5. METHODS: In 34 patients, 24-h ambulatory BP (A&D TM2421) was measured at baseline and every 4 months for 1 year or until the need for renal replacement therapy. For each BP recording patients...

  17. Longitudinal observations on circadian blood pressure variation in chronic kidney disease stages 3-5

    DEFF Research Database (Denmark)

    Elung-Jensen, T.; Strandgaard, S.; Kamper, Anne-Lise

    2008-01-01

    BACKGROUND: It has been suggested that status as a 'non-dipper' determined from 24-h blood pressure (BP) recordings is associated with increased risk of end-organ damage but little is known about the consistency of dipper status in renal patients. The present post hoc analysis evaluated dipper/no...

  18. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  19. Stage design

    International Nuclear Information System (INIS)

    Shacter, J.

    1975-01-01

    A method is described of cycling gases through a plurality of diffusion stages comprising the steps of admitting the diffused gases from a first diffusion stage into an axial compressor, simultaneously admitting the undiffused gases from a second diffusion stage into an intermediate pressure zone of said compressor corresponding in pressure to the pressure of said undiffused gases, and then admitting the resulting compressed mixture of diffused and undiffused gases into a third diffusion stage

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

    Energy Technology Data Exchange (ETDEWEB)

    Choudhuri, Ahsan [Univ. of Texas, El Paso, TX (United States). Dept. of Mechanical Engineering

    2013-06-30

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

  1. 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.

  2. Flow Pattern in a Fluidized Bed with a Non-fluidized Zone

    DEFF Research Database (Denmark)

    Lin, Weigang; Dam-Johansen, Kim; Van den Bleek, Cor. M.

    1997-01-01

    The flow pattern of a fluidized bed with non-fluidized zones is investigated both experimentally and theoretically. Experiments were carried out in such a way that air was introduced only through part of the distributor. The results show a significant amount of air flowing to the zone where no ai...

  3. Hydrodynamic study of the turbulent fluidized beds; Etude hydrodynamique des lits fluidises turbulents

    Energy Technology Data Exchange (ETDEWEB)

    Taxil, I.

    1996-12-20

    Gas-solid turbulent fluidization has already been widely studied in the literature. However, its definition and specificities remain controversial and confused. Most of the studies focussed on the turbulent transition velocities are based on wall pressure drop fluctuations studies. In this work, we first characterize the turbulent regime with the classical study of pressure drop signals with standard deviation analysis, completed with a more specific frequency analysis and also by a stochastic analysis. Then, we evaluate bubble flow properties. Experimental results have been obtained in a 0.2 m I.D. fluidized bed expanding to 0.4 m I.D. in the freeboard in order to limit entrainment at high fluidization velocities. The so lid used was FCC catalyst. It was fluidized by air at ambient conditions. The superficial fluidization velocity ranged 0.2 to 2 m/s. Fast response transducers recorded pressure drop at the wall and bubble flow properties (bubble size, bubble velocity and bubble frequency) could be deduced from a light reflected signal at various bed locations with optical fibers. It has been shown the turbulent regime is delimited by two velocities: Uc (onset of turbulent regime) and Utr (onset of transport regime), which can be determined based on standard deviations, dominant frequencies and width of wave land of pressure signals. The stochastic analysis confirms that the signal enriches in frequencies in the turbulent regime. Bubble size and bubble velocity could be correlated to the main superficial gas velocity. The main change in bubble flow in the turbulent regime was shown to be the stagnation of the bubble frequency at its maximum value. It was also shown that the bubble flow properties in the turbulent regime imply a strong aeration of the emulsion phase. (authors) 76 refs.

  4. A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Colby, R. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA (United States); Alsem, D.H. [Hummingbird Scientific, Lacey, WA (United States); Liyu, A.; Kabius, B. [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-06-15

    Environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ∼20 mbar achievable with a differentially pumped environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. However, the relationship between the pressure at the sample and the pressure drop across the system is not clear for some geometries. We demonstrate a method for measuring the gas pressure at the sample by measuring the ratio of elastic to inelastic scattering and the defocus of the pair of thin windows. This method requires two energy filtered high-resolution TEM images that can be performed during an ongoing experiment, at the region of interest. The approach is demonstrated to measure greater than atmosphere pressures of N{sub 2} gas using a commercially available gas-flow stage. This technique provides a means to ensure reproducible sample pressures between different experiments, and even between very differently designed gas-flow stages. - Highlights: • Method developed for measuring gas pressure within a gas-flow stage in the TEM. • EFTEM and CTF-fitting used to calculate amount and volume of gas. • Requires only a pair of images without leaving region of interest. • Demonstrated for P > 1 atm with a common commercial gas-flow stage.

  5. A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

    International Nuclear Information System (INIS)

    Colby, R.; Alsem, D.H.; Liyu, A.; Kabius, B.

    2015-01-01

    Environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ∼20 mbar achievable with a differentially pumped environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. However, the relationship between the pressure at the sample and the pressure drop across the system is not clear for some geometries. We demonstrate a method for measuring the gas pressure at the sample by measuring the ratio of elastic to inelastic scattering and the defocus of the pair of thin windows. This method requires two energy filtered high-resolution TEM images that can be performed during an ongoing experiment, at the region of interest. The approach is demonstrated to measure greater than atmosphere pressures of N 2 gas using a commercially available gas-flow stage. This technique provides a means to ensure reproducible sample pressures between different experiments, and even between very differently designed gas-flow stages. - Highlights: • Method developed for measuring gas pressure within a gas-flow stage in the TEM. • EFTEM and CTF-fitting used to calculate amount and volume of gas. • Requires only a pair of images without leaving region of interest. • Demonstrated for P > 1 atm with a common commercial gas-flow stage

  6. Misconduct Policies, Academic Culture and Career Stage, Not Gender or Pressures to Publish, Affect Scientific Integrity.

    Directory of Open Access Journals (Sweden)

    Daniele Fanelli

    Full Text Available The honesty and integrity of scientists is widely believed to be threatened by pressures to publish, unsupportive research environments, and other structural, sociological and psychological factors. Belief in the importance of these factors has inspired major policy initiatives, but evidence to support them is either non-existent or derived from self-reports and other sources that have known limitations. We used a retrospective study design to verify whether risk factors for scientific misconduct could predict the occurrence of retractions, which are usually the consequence of research misconduct, or corrections, which are honest rectifications of minor mistakes. Bibliographic and personal information were collected on all co-authors of papers that have been retracted or corrected in 2010-2011 (N=611 and N=2226 papers, respectively and authors of control papers matched by journal and issue (N=1181 and N=4285 papers, respectively, and were analysed with conditional logistic regression. Results, which avoided several limitations of past studies and are robust to different sampling strategies, support the notion that scientific misconduct is more likely in countries that lack research integrity policies, in countries where individual publication performance is rewarded with cash, in cultures and situations were mutual criticism is hampered, and in the earliest phases of a researcher's career. The hypothesis that males might be prone to scientific misconduct was not supported, and the widespread belief that pressures to publish are a major driver of misconduct was largely contradicted: high-impact and productive researchers, and those working in countries in which pressures to publish are believed to be higher, are less-likely to produce retracted papers, and more likely to correct them. Efforts to reduce and prevent misconduct, therefore, might be most effective if focused on promoting research integrity policies, improving mentoring and training

  7. Application of image processing on struvite recovery from swine wastewater by using the fluidized bed.

    Science.gov (United States)

    Ye, Zhi-Long; Deng, Yujun; Ye, Xin; Lou, Yaoyin; Chen, Shaohua

    2018-01-01

    Fluidized granulation is one of the common methods used in wastewater treatment and resource recovery with harvesting millimeter-scale large particles. Presently, effective methods are lacking to measure the fluidized granules ranging from micro- to millimeter scales, with the consequence of ineffectively controlling and optimizing the granulation process. In this work, recovering struvite (MgNH 4 PO 4 ·6H 2 O) from swine wastewater by using a fluidized bed was taken as an example. Image processing was applied to analyze the properties of different types of struvite granules, including morphology, particle size distribution, number density and mass concentration. Four stages of the struvite crystal evolution were therefore defined: aggregation, aggregate compaction, cluster-agglomerating and coating growth. These stages could occur simultaneously or sequentially. Up-flow rates of 30-80 mm/s in the fluidized bed sustained 600-876 g/L granular solids. Results revealed that the coating-growth granules were formed with compact aggregates or cluster-agglomerating granules as the nuclei. The growth rates for the different types of particles, including population growth, mass increase and particle size enlargement, were determined. In final, a schematic illustration for struvite granulation process is also presented.

  8. Process development and modeling of fluidized-bed reactor with coimmobilized biocatalyst for fuel ethanol production

    Science.gov (United States)

    Sun, May Yongmei

    This research focuses on two steps of commercial fuel ethanol production processes: the hydrolysis starch process and the fermentation process. The goal of this research is to evaluate the performance of co-immobilized biocatalysts in a fluidized bed reactor with emphasis on economic and engineering aspects and to develop a predictive mathematical model for this system. The productivity of an FBR is higher than productivity of a traditional batch reactor or CSTR. Fluidized beds offer great advantages over packed beds for immobilized cells when small particles are used or when the reactant feed contains suspended solids. Plugging problems, excessive pressure drops (and thus attrition), or crushing risks may be avoided. No mechanical stirring is required as mixing occurs due to the natural turbulence in the fluidized process. Both enzyme and microorganism are immobilized in one catalyst bead which is called co-immobilization. Inside this biocatalyst matrix, starch is hydrolyzed by the enzyme glucoamylase to form glucose and then converted to ethanol and carbon dioxide by microorganisms. Two biocatalysts were evaluated: (1) co-immobilized yeast strain Saccharomyces cerevisiae and glucoamylase. (2) co-immobilized Zymomonas mobilis and glucoamylase. A co-immobilized biocatalyst accomplishes the simultaneous saccharification and fermentation (SSF process). When compared to a two-step process involving separate saccharification and fermentation stages, the SSF process has productivity values twice that given by the pre-saccharified process when the time required for pre-saccharification (15--25 h) was taken into account. The SSF process should also save capital cost. The information about productivity, fermentation yield, concentration profiles along the bed, ethanol inhibition, et al., was obtained from the experimental data. For the yeast system, experimental results showed that: no apparent decrease of productivity occurred after two and half months, the productivity

  9. Investigation on side-spray fluidized bed granulation with swirling airflow.

    Science.gov (United States)

    Wong, Poh Mun; Chan, Lai Wah; Heng, Paul Wan Sia

    2013-03-01

    Top-spray fluidized bed granulation with axial fluidization airflow from the bottom of the granulator is well-established in the pharmaceutical industry. The application of swirling airflow for fluidized bed granulation was more recently introduced. This study examined the effects of various process parameters on the granules produced by side-spray fluidized bed with swirling airflow using the central composite and Box-Behnken design of experiment. Influence of the amount of binder solution, spray rate, and distance between spray nozzle and powder bed were initially studied to establish operationally viable values for these parameters. This was followed by an in-depth investigation on the effects of inlet airflow rate, atomizing air pressure and distance between spray nozzle and powder bed on granule properties. It was found that the amount of binder solution had a positive correlation with granule size and percentage of lumps but a negative correlation with size distribution and Hausner ratio of the granules. Binder solution spray rate was also found to affect the granules size. High drug content uniformity was observed in all the batches of granules produced. Both inlet airflow rate and atomizing air pressure were found to correlate negatively with granule size and percentage of lumps but correlate positively with the size distribution of the granule produced. Percentage of fines was found to be significantly affected by inlet airflow rate. Distance between spray nozzle and powder bed generally affected the percentage of lumps.

  10. Stages of polymer transformation during remote plasma oxidation (RPO) at atmospheric pressure

    Science.gov (United States)

    Luan, P.; Oehrlein, G. S.

    2018-04-01

    The interaction of cold temperature plasma sources with materials can be separated into two types: ‘direct’ and ‘remote’ treatments. Compared to the ‘direct’ treatment which involves energetic charged species along with short-lived, strongly oxidative neutral species, ‘remote’ treatment by the long-lived weakly oxidative species is less invasive and better for producing uniformly treated surfaces. In this paper, we examine the prototypical case of remote plasma oxidation (RPO) of polymer materials by employing a surface micro-discharge (in a N2/O2 mixture environment) treatment on polystyrene. Using material characterization techniques including real-time ellipsometry, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, the time evolution of polymer film thickness, refractive index, surface, and bulk chemical composition were evaluated. These measurements revealed three consecutive stages of polymer transformation, i.e. surface adsorption and oxidation, bulk film permeation and thickness expansion followed by the material removal as a result of RPO. By correlating the observed film thickness changes with simultaneously obtained chemical information, we found that the three stages were due to the three effects of weakly oxidative species on polymers: (1) surface oxidation and nitrate (R-ONO2) chemisorption, (2) bulk oxidation, and (3) etching. Our results demonstrate that surface adsorption and oxidation, bulk oxidation, and etching can all happen during one continuous plasma treatment. We show that surface nitrate is only adsorbed on the top few nanometers of the polymer surface. The polymer film expansion also provided evidence for the diffusion and reaction of long-lived plasma species in the polymer bulk. Besides, we found that the remote plasma etched surface was relatively rich in O-C=O (ester or carboxylic acid). These findings clarify the roles of long-lived weakly oxidative plasma species on polymers and advance

  11. Erosion study of final stage blading of low pressure steam turbines

    Science.gov (United States)

    Dehouve, J.; Nardin, P.; Zeghmati, M.

    1999-04-01

    In order to increase our knowledge of erosion phenomena, the Steam Turbine Groupe (STG) of ALSTOM has been using an erosion test facility in the C.R.T.V. (Centre de Recherche Turbines à Vapeur). This test facility simulates erosion in low pressure steam turbine cylinders in order to compare the erosion resistance of various blade materials (12% chromium steel, titanium alloys, etc.) and their protection (superficial hardening, coatings, etc.). This test facility also allows us to understand the mechanism causing damage at a macroscopic level (impact energy of the droplets and the loss of eroded volume) and at a microscopic level (residual stress and metallurgic analysis) and therefore to determine an evolution law of material surface damage. In this paper, the behaviour of the materials (12% chromium steel and titanium alloys), which has been analysed by image production measurement methods, will be presented according to different impact velocities.

  12. Results of theoretical and experimental studies of hydrodynamics of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors

    Science.gov (United States)

    Ryabov, G. A.; Folomeev, O. M.; Sankin, D. A.; Melnikov, D. A.

    2015-02-01

    Problems of the calculation of circulation loops in circulating fluidized bed reactors and systems with interconnected reactors (polygeneration systems for the production of electricity, heat, and useful products and chemical cycles of combustion and gasification of solid fuels)are considered. A method has been developed for the calculation of circulation loop of fuel particles with respect to boilers with circulating fluidized bed (CFB) and systems with interconnected reactors with fluidized bed (FB) and CFB. New dependences for the connection between the fluidizing agent flow (air, gas, and steam) and performance of reactors and for the whole system (solids flow rate, furnace and cyclone pressure drops, and bed level in the riser) are important elements of this method. Experimental studies of hydrodynamics of circulation loops on the aerodynamic unit have been conducted. Experimental values of pressure drop of the horizontal part of the L-valve, which satisfy the calculated dependence, have been obtained.

  13. Exploring the significance of the fluidized flow regime for avalanche hazard mapping

    Science.gov (United States)

    Issler, Dieter; Gauer, Peter

    Observational and experimental evidence suggests that it is important to explicitly account for the fluidized flow regime in avalanche hazard mapping due to its high mobility, intermediate density and high velocity. We explore the differences from conventional runout modelling by implementing an extension of the Norem-Irgens-Schieldrop (NIS) rheology in a simple mass-point model. When the dispersive stresses and the excess pore pressure equal the overburden pressure, the flow height increases and the density diminishes until a new equilibrium is reached, determined by the different density dependencies of the two parameters of the dispersive stresses. Fluidization requires sufficiently steep terrain; when it occurs it leads to substantially higher velocities than compared to the dense-flow regime. The model parameters are strongly constrained by their physical meaning and vary little between widely different avalanches. However, in all test cases we obtained better agreement between simulated and observed runout distances and pressure effects than with conventional models.

  14. IPP-rich milk protein hydrolysate lowers blood pressure in subjects with stage 1 hypertension, a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Kloek Joris

    2010-11-01

    Full Text Available Abstract Background Milk derived peptides have been identified as potential antihypertensive agents. The primary objective was to investigate the effectiveness of IPP-rich milk protein hydrolysates (MPH on reducing blood pressure (BP as well as to investigate safety parameters and tolerability. The secondary objective was to confirm or falsify ACE inhibition as the mechanism underlying BP reductions by measuring plasma renin activity and angiotensin I and II. Methods We conducted a randomized, placebo-controlled, double blind, crossover study including 70 Caucasian subjects with prehypertension or stage 1 hypertension. Study treatments consisted of daily consumption of two capsules MPH1 (each containing 7.5 mg Isoleucine-Proline-Proline; IPP, MPH2 (each containing 6.6 mg Methionine-Alanine-Proline, 2.3 mg Leucine-Proline-Proline, 1.8 mg IPP, or placebo (containing cellulose for 4 weeks. Results In subjects with stage 1 hypertension, MPH1 lowered systolic BP by 3.8 mm Hg (P = 0.0080 and diastolic BP by 2.3 mm Hg (P = 0.0065 compared with placebo. In prehypertensive subjects, the differences in BP between MPH1 and placebo were not significant. MPH2 did not change BP significantly compared with placebo in stage I hypertensive or prehypertensive subjects. Intake of MPHs was well tolerated and safe. No treatment differences in hematology, clinical laboratory parameters or adverse effects were observed. No significant differences between MPHs and placebo were found in plasma renin activity, or angiotensin I and II. Conclusions MPH1, containing IPP and no minerals, exerts clinically relevant BP lowering effects in subjects with stage 1 hypertension. It may be included in lifestyle changes aiming to prevent or reduce high BP. Trial registration ClinicalTrials.gov NCT00471263

  15. Fluidization behavior in a circulating slugging fluidized bed reactor. Part I: Residence time and residence time distribution of polyethylene solids

    NARCIS (Netherlands)

    van Putten, I.C.; van Sint Annaland, M.; Weickert, G.

    2007-01-01

    Square nosed slugging fluidization behavior in a circulating fluidized bed riser using a polyethylene powder with a very wide particle size distribution was studied. In square nosed slugging fluidization the extent of mixing of particles of different size depends on the riser diameter, gas velocity,

  16. Fluidized bed selective pyrolysis of coal

    Science.gov (United States)

    Shang, J.Y.; Cha, C.Y.; Merriam, N.W.

    1992-12-15

    The present invention discloses a process for the pyrolysis of coal which comprises the effective utilization of two zonal inclined fluidized beds, where said zones can be selectively controlled as to temperature and heating rate. The first zonal inclined fluidized bed serves as a dryer for crushed coal and additionally is controlled to selectively pyrolyze said coal producing substantially carbon dioxide for recycle use. The second zonal inclined fluidized bed further pyrolyses the coal to gaseous, liquid and char products under controlled temperature and heating rate zones designed to economically integrate the product mix. The gas and liquid products are recovered from the gaseous effluent stream while the char which remains can be further treated or utilized in a subsequent process step. 9 figs.

  17. Analysis of circulating fluidized bed combustion technology

    Energy Technology Data Exchange (ETDEWEB)

    Furusawa, Takehiko; Shimizu, Tadaaki; Yang, Guilin

    1987-05-20

    Fluidized bed combustors are commercialized as a technology to combust solid fuels with higher efficiency and lower emission and have functions of both combustion and simultaneous desulfurization and NOx reduction with dense phase fluidized beds but it is not so easy to realize these problems. The technology of circulating fluidized bed coal combustion is expected to offer potential break-through of various problems. But the details are not reported so far. Quantitative analysis of present situations was conducted and future problems were shown with officially available informations. This analysis includes the circulating rate and loading of solids, heat recovery and heat transfer rate as a function of loading of solids, the design of cyclones related to high solid concentration within the combustor, sulfur retention with reduced Ca/S ratio and problems related to NOx reduction to be developed in future. (51 refs, 23 figs, 8 tabs)

  18. Second stage gasifier in staged gasification and integrated process

    Science.gov (United States)

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

    2015-10-06

    A second stage gasification unit in a staged gasification integrated process flow scheme and operating methods are disclosed to gasify a wide range of low reactivity fuels. The inclusion of second stage gasification unit operating at high temperatures closer to ash fusion temperatures in the bed provides sufficient flexibility in unit configurations, operating conditions and methods to achieve an overall carbon conversion of over 95% for low reactivity materials such as bituminous and anthracite coals, petroleum residues and coke. The second stage gasification unit includes a stationary fluidized bed gasifier operating with a sufficiently turbulent bed of predefined inert bed material with lean char carbon content. The second stage gasifier fluidized bed is operated at relatively high temperatures up to 1400.degree. C. Steam and oxidant mixture can be injected to further increase the freeboard region operating temperature in the range of approximately from 50 to 100.degree. C. above the bed temperature.

  19. Effects of Friction and Anvil Design on Plastic Deformation during the Compression Stage of High-Pressure Torsion

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yuepeng; Chen, Miaomiao; Xu, Baoyan; Guo, Jing; Xu, Lingfeng; Wang, Zheng [Mechanical and Electronic Engineering College, Tai’an (China); Gao, Dongsheng [Shandong Provincial Key Laboratory of Horticultural Machineries and Equipments, Tai’an (China); Kim, Hyoung Seop [Department of Materials Science and Engineering, Pohang (Korea, Republic of)

    2016-11-15

    Herein, we report the results of our investigation on the effect of friction and anvil design on the heterogeneous plastic-deformation characteristics of copper during the compressive stage of high-pressure torsion (HPT), using the finite element method. The results indicate that the friction and anvil geometry play important roles in the homogeneity of the deformation. These variables affect the heterogeneous level of strain in the HPT compressed disks, as well as the flash in the disk edge region. The heterogeneous plastic deformation of the disks becomes more severe with the increasing depth of the cavity, as anvil angle and friction coefficient increase. However, the homogeneity increases with increases in the wall angle. The length of flash and the area of the dead metal zone increase with the depth of the cavity, while they decrease at a wall angle of 180°.

  20. Gas filtration in binary fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Rincon, J. (Univ. de Castilla-La Mancha, Ciudad Real (Spain)); Guardiola, J.; Romero, A. (Univ. de Alcala de Henares, Madrid (Spain))

    1992-12-01

    A systematic experimental study of aerosol filtration in a binary fluidized bed of dielectric material is carried out. Measurements of the collection efficiency when such parameters as gas velocity, bed height, collecting mixture, and column diameter are varied over a wide range have been made. Experimental evidence is given to show that charges generated naturally by triboelectrification of the bed dielectric particles can considerably increase the efficiency of such beds. Furthermore, it is demonstrated that a proper choice of the fluidized mixture can significantly improve the performance of such filters.

  1. VOC emission control by circulating fluidized bed adsorption; Controle de l'emission de composes organiques volatils par adsorption en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Song, W.

    2003-12-15

    This work deals with the circulating fluidized bed technology, applied to the elimination by adsorption of volatile organic compounds (VOCs), like toluene, in a gas flow. In the process, the adsorbent (millimetric spherical grains of micro-porous carbon) is moved by a strong flow rate of gas inside a vertical tube without lining. Mass and heat transfers are very important and important volumes of compounds can be processed. This work presents the determination of the adsorption equilibrium, the description of the experimental facility and of the results of experiments, the development of an original model of the process which combines a flow model and a mass transfer model, a parametric study of this model, and finally, some extensions of the process principle to staged operations with pressure variation or temperature variation cycles. (J.S.)

  2. Reliability of center of pressure measures for assessing the development of sitting postural control through the stages of sitting.

    Science.gov (United States)

    Wickstrom, Jordan; Stergiou, Nick; Kyvelidou, Anastasia

    2017-07-01

    Cerebral palsy (CP) impairs an individual's ability to move and control one's posture. Unfortunately, the signs and symptoms of CP may not be apparent before age two. Evaluating sitting posture is a potential way to assess the developing mechanisms that contribute to CP. The purpose of this project was to determine the reliability of linear and nonlinear measures, including inter- and intrastage reliability, when used to analyze the center of pressure (COP) time series during the stages of sitting development in children with typical development (TD) and with/at-risk for cerebral palsy (CP). We hypothesized that nonlinear tools would be more reliable than linear tools in assessing childrens' sitting development, and reliability would increase with development. COP data was recorded for three trials at eight sessions. Linear parameters used were root mean square, range of sway for the anterior-posterior (AP) and medial-lateral (ML) directions, and sway path. Nonlinear parameters used were Approximate Entropy, the largest Lyapunov Exponent, and Correlation Dimension for the AP and ML direction. Participants consisted of 33 children with TD and 26 children with/at-risk for CP. Our results determined that COP is a moderately reliable method for assessing the development of sitting postural control in stages in both groups. Thus, clinicians may be able to use measures from COP data across stages to assess the efficacy of therapeutic interventions that are intended to improve sitting postural abilities in children with/at-risk for CP. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Simulation modeling of fluidized bed coal gasifier for new topping cycle system

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Guilin; Yamazaki, Ryohei; Mori, Shigekatsu; Fujima, Yukihisa [Nagoya Univ. (Japan). Dept. of Chemical Engineering

    1997-12-31

    A new topping cycle coal power generation process is to be developed as a Japanese national project of high efficiency power generation process of coal. This process consists of a combination system of a pressurized bubbling fluidized-bed coal gasifier and a pressurized bubbling fluidized-bed combustor in series. To evaluate the performances and also to determine specifications and operation parameters of this process, it is extremely important to analyze the behavior and the performance of this system by a reasonable simulation model. A simulation model of this new process is developed in this paper. It is demonstrated by calculated results from this model that the carbon conversion in the gasifier, the composition and the heating value of produced gas are strongly dependent on operating conditions. Heat recovery by the steam in the combustor is also estimated as the function of coal feed rate.

  4. 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...

  5. Fluidized bed electrowinning of copper. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-01

    The objectives of the study were to: design and construct a 10,000- amp fluidized bed electrowinning cell for the recovery of copper from acidic sulfate solutions; demonstrate the technical feasibility of continuous particle recirculation from the electrowinning cell with the ultimate goal of continuous particle removal; and measure cell efficiency as a function of operating conditions.

  6. Fluidized-Bed Silane-Decomposition Reactor

    Science.gov (United States)

    Iya, Sridhar K.

    1991-01-01

    Fluidized-bed pyrolysis reactor produces high-purity polycrystalline silicon from silane or halosilane via efficient heterogeneous deposition of silicon on silicon seed particles. Formation of silicon dust via homogeneous decomposition of silane minimized, and deposition of silicon on wall of reactor effectively eliminated. Silicon used to construct solar cells and other semiconductor products.

  7. 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

  8. Fluidization Behavior of Oil-Contaminated Sand.

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Trnka, Otakar; Pohořelý, Michael

    2007-01-01

    Roč. 61, 2 (2007) , s. 93-97 ISSN 0366-6352 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized bed * hydrodynamics * oil pollution Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.367, year: 2007

  9. Formation and removal of biomass-derived contaminants in fluidized-bed gasification processes

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1996-12-31

    The objectives of this thesis were to examine the effects of the feedstock and the operating conditions of a fluidized-bed gasifier on the formation of tars and nitrogen-containing compounds and to study the effectiveness of the hot gas cleaning methods developed for the removal of particulates, alkali metals, tars and nitrogen-containing compounds. The most essential part of the work was carried out in the pressurized fluidized-bed gasification test facilities composed of an air-blown bubbling fluidized-bed gasifier and subsequent hot gas filter unit. The operation pressure of the test rig could be varied in the range 0.3 - 1.0 MPa and the maximum allowable gasification temperature was 1 050 deg C. The maximum capacity with biomass fuels was 80 kg/h. A wide range of feedstocks from hard coals, lignite and peat to different wood derived fuels and straw were used in the gasification tests. Two different types of ceramic filters were tested in the filter unit connected to the pressurized fluidized-bed gasifier. The filter unit was operated in a temperature range of 400 - 740 deg C. The particulate removal requirements set by the gas turbines were met by both types of filters and with product gases derived from all the feedstocks tested. In addition to the gasification and gas filtration tests, catalytic tar and ammonia decomposition was studied using both laboratory and bench-scale test facilities. Inexpensive calcium-based bulk materials, dolomites and limestones, were efficient tar decomposition catalysts in atmospheric-pressure tests

  10. Study of Stage-wise Pressure Pulsation in an Electric Submersible Pump under Variable Frequency Operation at Shut-off Condition

    Science.gov (United States)

    Dhanasekaran, A.; Kumaraswamy, S.

    2018-01-01

    Pressure pulsation causes vibration in the Electric Submersible Pump (ESP) and affects the life and performance of its system. ESP systems are installed at depths ranging from a few meters to several hundred meters. Unlike pumps used on the surface, once they are installed they become inaccessible for maintenance or for any kind of diagnostic measurement that might be taken directly on them. Therefore a detailed knowledge of mean and fluctuating pressures is required to achieve an optimal pressure distribution inside the ESP. This paper presents the results of an experimental investigation of the stage-wise pulsating pressure in ESP at shut-off condition at different speeds. Experiments were conducted on a pump having five stages. A variable frequency drive was used to operate the pump at five different speeds. Piezoresistive transducers were mounted at each stage of ESP to capture the unsteady pressure signals. Fast Fourier Transformation was carried out on the pressure signals to convert into frequency domain and the spectra of pressure pulsation signals were analyzed. The obtained results indicated the existence of fundamental frequency corresponding to the speed of rotation times the number of impeller blades and of the whole series of harmonics of higher frequencies.

  11. High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas-liquid fluidized bed reactor.

    Science.gov (United States)

    Yuan, G; Chen, D; Yin, L; Wang, Z; Zhao, L; Wang, J Y

    2014-06-01

    In this research a gas-liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas-liquid fluidized bed reactor was running at 280-320 °C, where hot N2 was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N2 to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N2 gas was set around 0.47-0.85 Nm(3) kg(-1) for the molten PVC. Larger N2 flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N2 flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas-liquid fluidized bed reactor for dechlorination. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. A CFD Case Study of a Fan Stage with Split Flow Path Subject to Total Pressure Distortion Inflow

    Science.gov (United States)

    To, Wai-Ming

    2017-01-01

    This report is the documentation of the work performed under the Hypersonic Project of the NASA's Fundamental Aeronautics Program. It was funded through Task Number NNC10E444T under GESS-2 Contract NNC06BA07B. The objective of the task is to develop advanced computational tools for the simulation of multi-stage turbomachinery in support of aeropropulsion. This includes work elements in extending the TURBO code and validating the multi-stage URANS (Unsteady Reynolds Averaged Navier Stokes) simulation results with the experimental data. The unsteady CFD (Computation Fluid Dynamics) calculations were performed in full wheel mode with and without screen generated total pressure distortion at the computational inflow boundary, as well as in single passage phase lag mode for uniform inflow. The experimental data were provided by NASA from the single stage RTA (Revolutionary Turbine Accelerator) fan test program.Significant non-uniform flow condition at the fan-face of the aeropropulsion system is frequentlyencountered in many of the advanced aerospace vehicles. These propulsion systems can be eithera podded or an embedded design employed in HWB (Hybrid Wing Body) airframe concept. It isalso a topic of interest in military applications, in which advanced air vehicles have already deployedsome form of embedded propulsion systems in their design because of the requirementsof compact and low observable inlets. Even in the conventional airframe/engine design, the fancould operate under such condition when the air vehicle is undergoing rapid maneuvering action.It is believed that a better understanding of the fan’s aerodynamic and aeromechanical responseto this type of operating condition or off design operation would be beneficial to designing distortiontolerant blades for improved engine operability.The objective for this research is to assess the capability of turbomachinery code as an analysistool in understanding the effects and evaluating the impact of flow distortion

  13. Granulation of acetaminophen by a rotating fluidized-bed granulator.

    Science.gov (United States)

    Kawaguchi, T; Sunada, H; Yonezawa, Y; Danjo, K; Hasegawa, M; Makino, T; Sakamoto, H; Fujita, K; Tanino, T; Kokubo, H

    2000-01-01

    The purpose of this research was to evaluate the use of a rotating fluidized-bed granulator to produce acetaminophen granules with sufficient binding force between particles and good plasticity in tablets. Ethenzamide and ascorbic acid were used to compare the relationship between granulation and the sample wetness. It was revealed that a blade rotation rate of 300 rpm, inlet air flow rate of 42 m3/hr, and spraying pressure of 1.5 kg/cm3 produced tablets with the best properties. The granule and tablet properties of ethenzamide and ascorbic acid were compared to those of acetaminophen. These compounds showed different wetting behaviors with water and different compression behaviors. With an increase in medicament content, tablet hardness increased except for the ascorbic acid formulation. Capping and sticking were observed in acetaminophen and in ascorbic acid, respectively, and acetaminophen and ethenzamide showed prolonged disintegration time.

  14. Polycyclic aromatic hydrocarbon (PAH) emission from co-firing of petrochemical sludge with coal in circulating fluidized bed incinerator

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, G.; Zhao, C.S. [South East University, Nanjing (China). School of Energy & Environment

    2009-07-01

    Experimental tests of polycyclic aromatic hydrocarbon (PAH) emission characteristics from co-firing of petrochemical sludge with coal were conducted in it pilot-scale circulating fluidized bed (CFB) incinerator with the thermal input of 0.2 MW. Results showed that when the mass mixing ratio increases from 10 to 40%, PAH, especially lower molecular weight (LMW) PAH, emission increases substantially. As combustion temperature or excess air coefficient increases, PAH emission decreases at first and then increases. There is an optimum combustion temperature and excess air coefficient for inhibiting PAHs formulation. PAH emission declines significantly when the secondary air fraction is increased from 20 to 50%. The staged combustion technique of circulating fluidized beds may have the advantage of inhibiting the formation of PAHs, Some optimized operation parameters are recommended for incineration of petrochemical sludge with coal in a circulating fluidized bed incinerator.

  15. Development of an enzyme fluidized bed reactor equipped with static mixers: application to lactose hydrolysis in whey

    Energy Technology Data Exchange (ETDEWEB)

    Fauquex, P.F.; Flaschel, E.; Renken, A.

    1984-01-01

    Reactor operation with immobilized enzymes in fixed bed arrangement is often impaired due to the presence of finely divided solid matter, adsorbing substances or gas. The fluidized bed reactor would be applied in such cases owing to a limited pressure drop, a controlled voidage, and the avoidance of perforated plates for catalyst retention. Since enzymic reactions are often slow processes, catalysts of high external surface area should be provided together with sufficient time. However, classical fluidized beds suffer from hydrodynamic instability under these conditions. Therefore, a new reactor design was developed which used motionless mixers as internals. Fluidized bed reactors equipped with internals exhibit an outstanding hydrodynamic stability accompanied by an increase of the operating range in terms of flow rate by a factor of 4 compared to the classical fluidized bed. Results are presented, with emphasis on the backmixing and expansion characteristics. Various motionless mixers were investigated in columns of 39 and 150 mm in diameter. The fluidized bed equipped with internals was used for lactose hydrolysis in partially deproteinized whey. The lactase from Aspergillus niger immobilized on silica gel particles of 125-160 molm had a half-life of approximately 1 mo.

  16. Effects of hemodialysis on corneal and anterior chamber morphometry and intraocular pressure in patients with end-stage renal disease

    Directory of Open Access Journals (Sweden)

    Mehtap Caglayan

    Full Text Available ABSTRACT Purpose: To evaluate the effects of hemodialysis (HD on corneal and anterior chamber morphometry, as well as intraocular pressure (IOP in patients with end-stage renal disease. Methods: Fifty right eyes were examined 30 minutes before and after HD. IOP was measured with a Goldmann applanation tonometer, and Ehlers' formula was used to calculate the corrected IOP values. The central corneal thickness (CCT, corneal volume (CV, keratometric values, anterior chamber depth (ACD, aqueous depth (AQD, anterior chamber volume (ACV, and anterior chamber angle (ACA in the nasal and temporal quadrants were measured with a Sirius anterior segment analysis system. Blood urea nitrogen levels, body mass, and systolic and diastolic arterial pressure were also measured before and after HD. Results: The mean age was 60.80 ± 13.38 (range: 35-80 years. The mean uncorrected and corrected IOP values decreased from 18.06 ± 3.91 and 18.31 ± 4.83 mmHg to 16.94 ± 3.87 and 16.95 ± 4.74 mmHg after HD, respectively (p=0.011 and p=0.003, respectively. The mean CCT decreased from 536.38 ± 24.73 to 533.18 ± 27.25 µm (p=0.002, and the mean CV decreased from 57.52 ± 3.15 to 55.68 ± 3.55 mm³ (p0.05 for all values. There were no significant correlations between the ocular and systemic parameters (p>0.05 for all correlations. Conclusions: Uncorrected IOP, corrected IOP, CCT, and CV values decreased after HD, whereas the anterior chamber morphometry values remained similar between the measurements performed before and after HD.

  17. The formation of impurities in fluidized-bed gasification of biomass, peat and coal; Epaepuhtauksien muodostuminen leijukerroskaasutuksessa

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E.; Laatikainen-Luntama, J.; Kurkela, M.; Leppaelahti, J.; Koljonen, T.; Oesch, P. [VTT Energy, Espoo (Finland); Alen, R. [Jyvaeskylae Univ. (Finland)

    1996-12-01

    The objective of this three-year-long project was to study the effects of different process parameters and bed materials on the formation of impurities in pressurized fluidized-bed gasification. The main emphasis of the project was focused on the formation of tars and nitrogen compounds in wood, peat and coal gasification. The aims of the research were to find out such operating conditions, where the formation of problematic high-molecular-weight tars can be minimised and to create a better understanding on the fate of fuel nitrogen in fluidized-bed gasifiers. Main part of the research was carried out in a bench-scale pressurised fluidized-bed reactor (ID 30 mm), where the effects of pressure, temperature, gas atmosphere and bed material were studied with different feedstocks. Most of the test series were carried out using the same feedstocks as earlier used in the PDU-scale fluidized-bed gasification tests of VTT (pine wood, pine bark, wheat straw, two peats, Rhenish brown coal, Polish and Illinois No.6 bituminous coals). The effects of operating parameters on the product yields (gas components, tars, char) were first studied under inert nitrogen atmosphere. The conversion of fuel nitrogen into ammonia and HCN were also determined for the different feedstocks over the different operating conditions. These studies showed that ammonia is the main fixed nitrogen compound of fluidized-bed pyrolysis with all the feedstocks studied. The conversions of fuel nitrogen into ammonia and HCN was highest with the high volatile fuels and lowest with the two hard coals. Gas atmosphere had a dramatic effect on the conversion of fuel nitrogen; much higher ammonia yields were determined in real gasification gas atmosphere than in inert pyrolysis carried out in N{sub 2} or Argon atmosphere. In addition to the pressurised fluidized-bed pyrolysis tests, laboratory scale pyrolysis research was carried out in order to compare the pyrolysis behaviour of the different feedstocks

  18. Modeling biomass gasification in circulating fluidized beds

    Science.gov (United States)

    Miao, Qi

    In this thesis, the modeling of biomass gasification in circulating fluidized beds was studied. The hydrodynamics of a circulating fluidized bed operating on biomass particles were first investigated, both experimentally and numerically. Then a comprehensive mathematical model was presented to predict the overall performance of a 1.2 MWe biomass gasification and power generation plant. A sensitivity analysis was conducted to test its response to several gasifier operating conditions. The model was validated using the experimental results obtained from the plant and two other circulating fluidized bed biomass gasifiers (CFBBGs). Finally, an ASPEN PLUS simulation model of biomass gasification was presented based on minimization of the Gibbs free energy of the reaction system at chemical equilibrium. Hydrodynamics plays a crucial role in defining the performance of gas-solid circulating fluidized beds (CFBs). A 2-dimensional mathematical model was developed considering the hydrodynamic behavior of CFB gasifiers. In the modeling, the CFB riser was divided into two regions: a dense region at the bottom and a dilute region at the top of the riser. Kunii and Levenspiel (1991)'s model was adopted to express the vertical solids distribution with some other assumptions. Radial distributions of bed voidage were taken into account in the upper zone by using Zhang et al. (1991)'s correlation. For model validation purposes, a cold model CFB was employed, in which sawdust was transported with air as the fluidizing agent. A comprehensive mathematical model was developed to predict the overall performance of a 1.2 MWe biomass gasification and power generation demonstration plant in China. Hydrodynamics as well as chemical reaction kinetics were considered. The fluidized bed riser was divided into two distinct sections: (a) a dense region at the bottom of the bed where biomass undergoes mainly heterogeneous reactions and (b) a dilute region at the top where most of homogeneous

  19. Experimental investigations on drying behaviour of Bulgarian brown coal in steam fluidized bed

    International Nuclear Information System (INIS)

    Buschsieweke, F.; Koenig, J.

    1999-01-01

    The main targets were: to investigate the parameters for optimizing the drying process as steam pressure, fluidization velocity and particle size; to identify the cost of drying and combustion processes considering the necessity of milling the coal (raw or dried). Test series with Bulgarian brown coal from Maritsa-East has been made. Two fractions with different particle size was got: A from 0 to 1.6 mm (0.5 mm average) and B, resp. 1.6 to 6.3 (1.7 mm). The particle size is depending on the coal moisture. The fluidized bed process with the both fractions was performed at variations of the following parameters: steam velocity (0.07 to 1.7 m/s); raw coal feed rate (4 to 16 kg/h); raw moisture (18 to 43 wt %) and pressure (1.3 and 5 bar). Also the shrinking behaviour of the coal in different pore sizes was tested. Comparing pore size of the oven dried coal to the fluidized bed dried coal, significantly higher inner surface for the oven dried coal was established. To indicate the pore size of raw coal samples were made by freeze drying. Ice expanding should cause higher inner surface compared to oven drying method but no significant difference was established. A significant increase of heat transfer of the particles from A fraction (300 to 350 W/m 2 K0 compared to B (200 to 230 W/m 2 K) was determined. The heat transfer coefficient increased at increasing of the raw coal feed rate, mostly significant for A, due to higher particle contact. In conclusion: the particle convective mechanism is predominant for the heat transfer; development of pressurized fluidized bed drying is not of interest and the question about the total expenditure for crushing and milling remains open

  20. The effects of stair climbing on arterial stiffness, blood pressure, and leg strength in postmenopausal women with stage 2 hypertension.

    Science.gov (United States)

    Wong, Alexei; Figueroa, Arturo; Son, Won-Mok; Chernykh, Oksana; Park, Song-Young

    2018-02-12

    Menopause is accompanied by a progressive arterial stiffening associated with increases in blood pressure (BP) and decline in muscular function. It is crucial to prevent or reduce the negative effects of menopause on vascular and muscular function by implementing appropriate lifestyle interventions, such as exercise training. We examined the effects of a stair climbing (SC) regimen on arterial stiffness (pulse wave velocity [PWV]), BP, and leg strength in postmenopausal women with stage 2 hypertension. Using a parallel experimental design, participants were randomly assigned to either SC (n = 21) or nonexercising control group (n = 20) for 12 weeks. Participants in the SC group trained 4 d/wk, climbing 192 steps 2 to 5 times/d. Participants' brachial-to-ankle PWV (baPWV), BP, and leg strength were measured at baseline and after 12 weeks of their assigned intervention. There was a significant group by time interaction (P hypertensive postmenopausal women. The decrease in arterial stiffness partially explained the improvements in SBP and leg strength. SC may be an effective intervention in the prevention and treatment of menopause/aging-related vascular complications and muscle weakness.

  1. Blood Pressure Test

    Science.gov (United States)

    ... pressure monitors may have some limitations. Tracking your blood pressure readings It can be helpful in diagnosing or ... more Stage 2 high blood pressure (hypertension) Elevated blood pressure and stages 1 and 2 high blood pressure ( ...

  2. 21 CFR 890.5160 - Air-fluidized bed.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Air-fluidized bed. 890.5160 Section 890.5160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5160 Air-fluidized bed. (a) Identification. An air-fluidized bed is a...

  3. Application of Scaling-Law and CFD Modeling to Hydrodynamics of Circulating Biomass Fluidized Bed Gasifier

    Directory of Open Access Journals (Sweden)

    Mazda Biglari

    2016-06-01

    Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.

  4. Improved steam gasification of lignocellulosic residues in a fluidized bed with commercial steam reforming catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.P.; Corella, J.; Delgado, J.; Lahoz, J. (Univ. of Zaragoza (Spain))

    1993-01-01

    The improved/two-stage steam gasification of biomass or lignocellulosic residues in fluidized bed with steam reforming catalysts placed in a downstream secondary reactor has been studied. Two commercial catalysts, R-67 and RKS-1 from Topsoee, were used at their incipient fluidization conditions. At 720-760 C and space-times of only 0.10-0.20 s, with catalyst sizes under 1.0 mm and with steam/biomass ratios of 1.2-1.6, tar conversions of 99.95% were achieved in the catalytic reactor. In this process, tar and methane in the flue gas can be easily lowered below 5 mg/m[sup 3](NTP) and 0.5 vol %, respectively, without using oxygen. The catalyst deactivation by coke from the tar cracking is the main problem of this process.

  5. Proceedings of the sixth international conference on fluidized bed combustion. Volume II. Technical sessions

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-08-01

    The Sixth International Conference on Fluidized Bed Combustion was held April 9-11, 1980, at the Atlanta Hilton, Atlanta, Georgia. It was sponsored by the US Department of Energy, the Electric Power Research Institute, the US Environmental Protection Agency, and the Tennessee Valley Authority. The papers covered recent developments in atmospheric and pressurized fluidized-bed combustion, especially the design, operation and control of pilot and demonstration plants. The cleanup of combustion products and the erosion, corrosion and fouling of gas turbines was emphasized also. Fifty-five papers from Volume 2 of the proceedings have been entered individually into EDB and ERA; five papers had been entered previously from other sources. (LTN)

  6. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  7. Circulating fluidized bed boilers design and operations

    CERN Document Server

    Basu, Prabir

    1991-01-01

    This book provides practicing engineers and students with insight into the design and operation of circulating fluidized bed (CFB) boilers. Through a combination of theoretical concepts and practical experience, this book gives the reader a basic understanding of the many aspects of this subject.Important environmental considerations, including solid waste disposal and predicted emissions, are addressed individually in separate chapters. This book places an emphasis on combustion, hydrodynamics, heat transfer, and material issues, and illustrates these concepts with numerous examples of pres

  8. Gas distributor for fluidized bed coal gasifier

    Science.gov (United States)

    Worley, Arthur C.; Zboray, James A.

    1980-01-01

    A gas distributor for distributing high temperature reaction gases to a fluidized bed of coal particles in a coal gasification process. The distributor includes a pipe with a refractory reinforced lining and a plurality of openings in the lining through which gas is fed into the bed. These feed openings have an expanding tapered shape in the downstream or exhaust direction which aids in reducing the velocity of the gas jets as they enter the bed.

  9. Reinforcement versus fluidization in cytoskeletal mechanoresponsiveness.

    Directory of Open Access Journals (Sweden)

    Ramaswamy Krishnan

    Full Text Available Every adherent eukaryotic cell exerts appreciable traction forces upon its substrate. Moreover, every resident cell within the heart, great vessels, bladder, gut or lung routinely experiences large periodic stretches. As an acute response to such stretches the cytoskeleton can stiffen, increase traction forces and reinforce, as reported by some, or can soften and fluidize, as reported more recently by our laboratory, but in any given circumstance it remains unknown which response might prevail or why. Using a novel nanotechnology, we show here that in loading conditions expected in most physiological circumstances the localized reinforcement response fails to scale up to the level of homogeneous cell stretch; fluidization trumps reinforcement. Whereas the reinforcement response is known to be mediated by upstream mechanosensing and downstream signaling, results presented here show the fluidization response to be altogether novel: it is a direct physical effect of mechanical force acting upon a structural lattice that is soft and fragile. Cytoskeletal softness and fragility, we argue, is consistent with early evolutionary adaptations of the eukaryotic cell to material properties of a soft inert microenvironment.

  10. Status of the fluidized bed unit

    International Nuclear Information System (INIS)

    Williams, P.M.; Wade, J.F.

    1994-01-01

    Rocky Flats has a serious mixed waste problem. No technology or company has a license and available facilities to remedy this dilemma. One solution under study is to use a catalytic fluidized bed unit to destroy the combustible portion of the mixed waste. The fluidized bed thermal treatment program at Rocky Flats is building on knowledge gained over twenty years of successful development activity. The FBU has numerous technical advantages over other thermal technologies to treat Rocky Flats' mixed waste, the largest being the lower temperature (700 degrees C versus 1000 degrees C) which reduces acid corrosion and mechanical failures and obviates the need for ceramic lining. Successful demonstrations have taken place on bench, pilot, and full-scale tests using radioactive mixed wastes. The program is approaching implementation and licensing of a production-scale fluidized bed system for the safe treatment of mixed waste. The measure for success on this project is the ability to work closely with the community to jointly solve problems and respond to concerns of mixed waste treatment at Rocky Flats

  11. Pulsed atmospheric fluidized-bed combustor development

    International Nuclear Information System (INIS)

    1992-05-01

    Pulsed atmospheric fluidized-bed combustion (PAFBC) is a unique and innovative coal-fueled technology that has the potential to meet these conditions and provide heat and/or process steam to small industrial, commercial, institutional and residential complexes. The potential of Pulse Atmospheric Fluidized Bed Combustion (PAFBC) technology has been amply demonstrated under the sponsorship of a previous DOE/METC contract (DE-AC21-88MC25069). The environmental performance of a coal-fired laboratory-scale system (1.5 million British Thermal Units per hour) (MMBtu/hr) significantly surpassed that of conventional bubbling and circulating fluidized-bed combustion units (see Table 1 for performance comparison). Prompted by these encouraging results in combustion, sulfur capture, emissions control, and enhanced heat transfer, Island Creek Coal Company (ICC) and Baltimore Thermal Energy Corporation expressed interest in the technology and offered to participate by providing host sites for field testing. EA's have been submitted independently for each of these field test sites. This submission addresses the preliminary testing of the PAFBC unit at Manufacturing and Technology Conversion International's (MTCI) Baltimore, MD facility

  12. Cold test with a benchtop set-up for fluidized bed reactor using quartz sand to simulate gasification of coal cokes by concentrated solar radiation

    Science.gov (United States)

    Gokon, Nobuyuki; Tanabe, Tomoaki; Shimizu, Tadaaki; Kodama, Tatsuya

    2016-05-01

    The impacts of internal circulation of a mixture of coal-coke particles and quartz sand on the fluidization state in a fluidized bed reactor are investigated by a cold test with a benchtop set-up in order to design 10-30 kWth scale prototype windowed fluidized-bed reactor. Firstly, a basic relationship between pressure loss of inlet gas and gas velocity was experimentally examined using quartz sand with different particle sizes by a small-scale quartz tube with a distributor at ambient pressure and temperature. Based on the results, an appropriate particle range of quartz sand and layer height/layer diameter ratio (L/D ratio) was determined for a design of the fluidized bed reactor. Secondly, a windowed reactor mock-up was designed and fabricated for solar coke gasification using quartz sand as a bed material. The pressure loss between the inlet and outlet gases was examined, and descending cokes and sand particles on the sidewall of the reactor was observed in the reactor mock-up. The moving velocity and distance of descending particles/sands from the top to bottom of fluidized bed were measured by the visual observation of the colored tracer particles on outside wall of the reactor.

  13. Physical activity and sedentary behaviour at different life stages and adult blood pressure in the 1958 British cohort.

    Science.gov (United States)

    Pouliou, Theodora; Ki, Myung; Law, Catherine; Li, Leah; Power, Chris

    2012-02-01

    To investigate whether physical activity or sedentary behaviour at different life stages is associated with blood pressure (BP) in mid-adulthood; activity levels have accumulative associations with BP; and adult body mass index (BMI) mediates associations. Information on activity and television-viewing was available at several ages (23, 33, 42, 45 years) and BP at 45 years for the 1958 British birth cohort (n = 9927). Associations were examined with and without adjustment for covariates. Active adults, generally, had lower mean systolic and diastolic BP and risk of hypertension than nonactive, although varying by age. After adjustment for covariates, systolic and diastolic BP for active men at 23 years or at 45 years were 1-2 mmHg lower; similar associations were seen for women active at 33 years. Some but not all associations attenuated with further adjustment for BMI: odds ratio (OR) for hypertension associated with 23 years activity changed from 0.82 [95% confidence interval (CI) 0.74, 0.91] to 0.79 (0.70, 0.90) after BMI adjustment. Independent associations of activity at more than one age were found, such that prevalence of hypertension was higher in men active at 23 years but not at 45 years, than men sustaining activity (39 vs. 31%). Sitting at work was unrelated to BP, but there was a trend of higher BP with greater television-viewing: for example risk of hypertension was higher by 10-12% per h/day television-viewing at 45 years after adjustment for covariates, attenuating after allowance for BMI. Our study suggests that there are benefits to BP of becoming and sustaining active lifestyles and minimizing television-viewing over many years of adulthood, with a mediating role for BMI.

  14. Heart rate response to blood pressure variations: sympathetic activation versus baroreflex response in patients with end-stage renal disease.

    Science.gov (United States)

    Sapoznikov, Dan; Dranitzki Elhalel, Michal; Rubinger, Dvora

    2013-01-01

    Continuous systolic blood pressure (SBP) and interbeat intervals (IBI) recordings reveal sequences of consecutive beats in which SBP and heart rate change in opposite direction, representing negative feedback baroreflex mechanisms, as well as sequences in which SBP and heart rate change in the same direction (non-baroreflex), believed to represent feedforward control mechanisms. The present study was undertaken to assess the relationship between baroreflex and non-baroreflex sequences in end stage renal insufficiency. Continuous beat-to-beat SBP and IBI monitoring was performed in patients on chronic hemodialysis (HD, n=72), in age-matched patients after renal transplantation (TX, n=41) and healthy (control) individuals (C, n=34). The proportion of baroreflex and nonbaroreflex episodes and the b coefficients (the regression line slope of SBP-IBI correlation) were determined using a newly developed 1 minute sliding window method, the classical sequence technique and the "Z" coefficient method. Analysis using the 1 minute sliding window showed an increased proportion of baroreflex episodes in controls and HD, and predominance of nonbaroreflex episodes in TX. An increased proportion of nonbaroreflex episodes in TX patients relative to HD was also revealed by the "Z" method. Baroreflex and nonbaroreflex b coefficients obtained by all methods were markedly decreased in HD. This alteration was reversed at least partly in TX. In HD, both baroreflex and nonbaroreflex b coefficients were inversely correlated to age and CRP levels; in TX, the nonbaroreflex b coefficient was influenced by the type of calcineurin inhibitor. Renal status affects the contribution of baroreflex and nonbaroreflex mechanisms and the strength of SBP-IBI relationship. The predominant contribution of nonbaroreflex mechanisms in TX may be suggestive of enhanced central sympathetic control. Our data may be relevant for understanding of the pathogenesis and selection of appropriate treatment of post

  15. Method for fluidizing and coating ultrafine particles, device for fluidizing and coating ultrafine particles

    Science.gov (United States)

    Li, Jie; Liu, Yung Y

    2015-01-20

    The invention provides a method for dispersing particles within a reaction field, the method comprising confining the particles to the reaction field using a standing wave. The invention also provides a system for coating particles, the system comprising a reaction zone; a means for producing fluidized particles within the reaction zone; a fluid to produce a standing wave within the reaction zone; and a means for introducing coating moieties to the reaction zone. The invention also provides a method for coating particles, the method comprising fluidizing the particles, subjecting the particles to a standing wave; and contacting the subjected particles with a coating moiety.

  16. Glycaemic, blood pressure and lipid goal attainment and chronic kidney disease stage of type 2 diabetic patients treated in primary care practices.

    Science.gov (United States)

    Corcillo, Antonella; Pivin, Edward; Lalubin, Fabrice; Pitteloud, Nelly; Burnier, Michel; Zanchi, Anne

    2017-07-11

    The prevalence of chronic kidney disease and diabetes is rising in Europe. These patients are at high cardiovascular and renal risk and need a challenging multifactorial therapeutic approach. The goal of this cross-sectional study was to examine the treatment and attainments of goals related to cardiovascular risk factors within chronic kidney disease stages in type 2 diabetic patients followed up by primary care physicians in Switzerland. Each participating physician entered into a web database the anonymised data of up to 15 consecutive diabetic patients attending her/his office between December 2013 and June 2014. Diabetes, hypertension and lipid lowering therapies were analysed, as well as glycated haemoglobin (HbA1c), blood pressure and low-density lipoprotein-cholesterol (LDL-c) levels and goal attainments by KDIGO chronic kidney disease stage 1 to 4. A total of 1359 patients (mean age 66.5±12.4 years) were included by 109 primary care physicians. Chronic kidney disease stages 0-2, 3a, 3 b and 4 were present in 77.6%, 13.9%, 6.1%, and 2.4%, respectively. Average HbA1c was independent of chronic kidney disease stage and close to 7%; more than half of the patients reached the HbA1c goal. Eighty-four percent of patients were hypertensive and only 18.2% reached the then current Swiss or American Diabetes Association 2013 blood pressure goals. Despite loosening of blood pressure goals in 2015, only half of the patients reached them and most needed multiple therapies. Increased body mass index and advanced chronic kidney disease stage decreased the chance of reaching blood pressure goals. Lipid lowering therapy was prescribed in 62.1% of cases, with average LDL-c levels similar across chronic kidney disease stages. Only 42% of patients reached the LDL-c goal of primary prevention and 32% reached primary care physicians in Switzerland. Goal attainments for HbA1c and LDL-c were not influenced by chronic kidney disease stages, in contrast to blood pressure. Reaching

  17. Fluidized Bed Asbestos Sampler Design and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Karen E. Wright; Barry H. O' Brien

    2007-12-01

    A large number of samples are required to characterize a site contaminated with asbestos from previous mine or other industrial operations. Current methods, such as EPA Region 10’s glovebox method, or the Berman Elutriator method are time consuming and costly primarily because the equipment is difficult to decontaminate between samples. EPA desires a shorter and less costly method for characterizing soil samples for asbestos. The objective of this was to design and test a qualitative asbestos sampler that operates as a fluidized bed. The proposed sampler employs a conical spouted bed to vigorously mix the soil and separate fine particulate including asbestos fibers on filters. The filters are then analyzed using transmission electron microscopy for presence of asbestos. During initial testing of a glass prototype using ASTM 20/30 sand and clay fines as asbestos surrogates, fine particulate adhered to the sides of the glass vessel and the tubing to the collection filter – presumably due to static charge on the fine particulate. This limited the fines recovery to ~5% of the amount added to the sand surrogate. A second prototype was constructed of stainless steel, which improved fines recovery to about 10%. Fines recovery was increased to 15% by either humidifying the inlet air or introducing a voltage probe in the air space above the sample. Since this was not a substantial improvement, testing using the steel prototype proceeded without using these techniques. Final testing of the second prototype using asbestos suggests that the fluidized bed is considerably more sensitive than the Berman elutriator method. Using a sand/tremolite mixture with 0.005% tremolite, the Berman elutriator did not segregate any asbestos structures while the fluidized bed segregated an average of 11.7. The fluidized bed was also able to segregate structures in samples containing asbestos at a 0.0001% concentration, while the Berman elutriator method did not detect any fibers at this

  18. The Influence of the Distributor Plate on the Bottom Zone of a Fluidized Bed Approaching the Transition from Bubbling to Turbulent Fluidization

    OpenAIRE

    Paiva, J. M.; Pinho, C.; Figueiredo, R.

    2004-01-01

    The dynamics of the bottom zone of a narrow fluidized bed, from bubbling to turbulent regimes, was studied in a cold model of 0.1 m i.d. and 1.3 m high. Tested distributor types were perforated perspex plates, with six different perforation grids, metallic mesh and porous ceramic, with pressures drops ranging from 0.05 to 350 kPa, corresponding to superficial air velocities from 0.1 to 2.3m s-1. Group B silica ballotini, within the range 0.355-0.425 mm, were used as bed material. The experime...

  19. Artificial Neural Network Modeling of an Inverse Fluidized Bed ...

    African Journals Online (AJOL)

    The application of neural networks to model a laboratory scale inverse fluidized bed reactor has been studied. A Radial Basis Function neural network has been successfully employed for the modeling of the inverse fluidized bed reactor. In the proposed model, the trained neural network represents the kinetics of biological ...

  20. Propylene polymerization in a circulating slugging fluidized bed reactor

    NARCIS (Netherlands)

    van Putten, I.C.

    2004-01-01

    The work presented in this thesis is concerned with research on the riser of a circulating fluidized bed system for olefin polymerization. In the riser section, fluidization takes place in the transporting slugging mode and polymer particles are produced in the riser in a non-isothermal way.

  1. Heat exchanger support apparatus in a fluidized bed

    Science.gov (United States)

    Lawton, Carl W.

    1982-01-01

    A heat exchanger is mounted in the upper portion of a fluidized combusting bed for the control of the temperature of the bed. A support, made up of tubes, is extended from the perforated plate of the fluidized bed up to the heat exchanger. The tubular support framework for the heat exchanger has liquid circulated therethrough to prevent deterioration of the support.

  2. Hydrodynamic studies in designing of fluidized bed system

    International Nuclear Information System (INIS)

    Mohamad Puad Abu; Muhd Noor Muhd Yunus; Syed Nasaruddin Syed Idris

    2002-01-01

    Fluidized bed process have been used mostly in the petroleum and paper industries, and for processing nuclear wastes, spent cook liquor, wood chips, and sewage sludge disposal. Even at MINT some of the equipment available used this principal. Before we use or purchase this equipment, it is very grateful if we could understand how the system has been designed. The hydrodynamic fluidization studies is very important in designing of fluidized bed system especially in determining the minimum fluidizing velocity, terminal velocity, flexibility of operation, slugging condition, bubble size and velocity, and transport disengaging height. They can be determined either by calculation or experimentation. This paper will highlight the hydrodynamic study that need to be performed in designing of fluidized bed system so that its can be used appropriately. (Author)

  3. ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Andy Wu; John T. Riley

    2005-04-30

    This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period January 1, 2005 through March 31, 2005. The following tasks have been completed. First, the renovation of the new Combustion Laboratory is nearly complete, and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building is in the final stages. Second, the fabrication and manufacture of the CFBC Facility is being discussed with a potential contractor. Discussions with potential contactor regarding the availability of materials and current machining capabilities have resulted in the modification of the original designs. The selection of the fabrication contractor for the CFBC Facility is expected during the next quarter. Third, co-firing experiments conducted with coal and chicken waste have been initiated in the laboratory-scale simulated fluidized-bed facility. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report.

  4. ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Andy Wu; John T. Riley

    2005-07-30

    This purpose of this report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period April 1, 2005 through June 30, 2005. The following tasks have been completed. First, the new Combustion Laboratory was occupied on June 15, 2005, and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building is in the final painting stage. Second, the fabrication and manufacturing contract for the CFBC Facility was awarded to Sterling Boiler & Mechanical, Inc. of Evansville, Indiana. Sterling is manufacturing the assembly and component parts of the CFBC system. The erection of the CFBC system is expected to start September 1, 2005. Third, mercury emissions from the cofiring of coal and chicken waste was studied experimentally in the laboratory-scale simulated fluidized-bed combustion facility. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described.

  5. Analysis of fluidized bed granulation process using conventional and novel modeling techniques.

    Science.gov (United States)

    Petrović, Jelena; Chansanroj, Krisanin; Meier, Brigitte; Ibrić, Svetlana; Betz, Gabriele

    2011-10-09

    Various modeling techniques have been applied to analyze fluidized-bed granulation process. Influence of various input parameters (product, inlet and outlet air temperature, consumption of liquid-binder, granulation liquid-binder spray rate, spray pressure, drying time) on granulation output properties (granule flow rate, granule size determined using light scattering method and sieve analysis, granules Hausner ratio, porosity and residual moisture) has been assessed. Both conventional and novel modeling techniques were used, such as screening test, multiple regression analysis, self-organizing maps, artificial neural networks, decision trees and rule induction. Diverse testing of developed models (internal and external validation) has been discussed. Good correlation has been obtained between the predicted and the experimental data. It has been shown that nonlinear methods based on artificial intelligence, such as neural networks, are far better in generalization and prediction in comparison to conventional methods. Possibility of usage of SOMs, decision trees and rule induction technique to monitor and optimize fluidized-bed granulation process has also been demonstrated. Obtained findings can serve as guidance to implementation of modeling techniques in fluidized-bed granulation process understanding and control. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. An Experimental and Numerical Investigation of Fluidized Bed Gasification of Solid Waste

    Directory of Open Access Journals (Sweden)

    Sharmina Begum

    2013-12-01

    Full Text Available Gasification is a thermo-chemical process to convert carbon-based products such as biomass and coal into a gas mixture known as synthetic gas or syngas. Various types of gasification methods exist, and fluidized bed gasification is one of them which is considered more efficient than others as fuel is fluidized in oxygen, steam or air. This paper presents an experimental and numerical investigation of fluidized bed gasification of solid waste (SW (wood. The experimental measurement of syngas composition was done using a pilot scale gasifier. A numerical model was developed using Advanced System for Process ENgineering (Aspen Plus software. Several Aspen Plus reactor blocks were used along with user defined FORTRAN and Excel code. The model was validated with experimental results. The study found very similar performance between simulation and experimental results, with a maximum variation of 3%. The validated model was used to study the effect of air-fuel and steam-fuel ratio on syngas composition. The model will be useful to predict the various operating parameters of a pilot scale SW gasification plant, such as temperature, pressure, air-fuel ratio and steam-fuel ratio. Therefore, the model can assist researchers, professionals and industries to identify optimized conditions for SW gasification.

  7. Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops.

    Science.gov (United States)

    Warriner, David R; Brown, Alistair G; Varma, Susheel; Sheridan, Paul J; Lawford, Patricia; Hose, David R; Al-Mohammad, Abdallah; Shi, Yubing

    2014-01-01

    The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models. A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax). For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

  8. Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops.

    Directory of Open Access Journals (Sweden)

    David R Warriner

    Full Text Available INTRODUCTION: The American Heart Association (AHA/American College of Cardiology (ACC guidelines for the classification of heart failure (HF are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV pressure-volume (PV loop data and secondly use the LV PV loop data to create stage specific HF models. METHODS AND RESULTS: A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV, ejection fraction (EF% decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax. CONCLUSIONS: For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

  9. Boost Pressure Control Strategy to Account for Transient Behavior and Pumping Losses in a Two-Stage Turbocharged Air Path Concept

    Directory of Open Access Journals (Sweden)

    Thivaharan Albin

    2016-07-01

    Full Text Available Increasingly complex air path concepts are investigated to achieve a substantial reduction in fuel consumption while improving the vehicle dynamics. One promising technology is the two-stage turbocharging for gasoline engines, where a high pressure and a low pressure turbocharger are placed in series. For exploiting the high potential, a control concept has to be developed that allows for coordinated management of the two turbocharger stages. In this paper, the control strategy is investigated. Therefore, the effect of the actuated values on transient response and pumping losses is analyzed. Based on these findings, an optimization-based control algorithm is developed that allows taking both requirements into account. The developed new controller allows achieving a fast transient response, while at the same time reducing pumping losses in stationary operation.

  10. Comparative effect of fixed dose combination of Amlodipine + Bisoprolol versus Amlodipine and Bisoprolol alone on blood pressure in stage-2 essential hypertensive patients.

    Directory of Open Access Journals (Sweden)

    Shirure PA,Tadvi NA, Bajait CS, Baig MS, Gade PR

    2012-09-01

    Full Text Available Background: Employment of low dose combinations of two antihypertensives, with different mode of action has gained acceptance worldwide for the treatment of mild to moderate hypertension. However, most studies in hypertensive disease have focused on monotherapy. The combination therapy in the treatment of hypertension is largely extrapolated from these monotherapy studies. Objectives: To study and compare the effect of amlodipine, bisoprolol and fixed dose combination of amlodipine + bisoprolol on blood pressure in stage-2 essential hypertensive patients. Methods: The present study was carried out in Department of Pharmacology in collaboration with Department of Medicine at Government Medical College and Hospital, Aurangabad. Results and Conclusion : Amlodipine + bisoprolol in fixed dose combination have showed significant blood pressure control in patients of stage-2 essential hypertension and the antihypertensive effect was greater than individual monotherapy study groups.

  11. INVESTIGATION OF FUEL CHEMISTRY AND BED PERFORMANCE IN A FLUIDIZED BED BLACK LIQUOR STEAM REFORMER

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Whitty

    2003-12-01

    The University of Utah project ''Investigation of Fuel Chemistry and Bed Performance in a Fluidized Bed Black Liquor Steam Reformer'' (DOE award number DE-FC26-02NT41490) was developed in response to a solicitation for projects to provide technical support for black liquor and biomass gasification. The primary focus of the project is to provide support for a DOE-sponsored demonstration of MTCI's black liquor steam reforming technology at Georgia-Pacific's paper mill in Big Island, Virginia. A more overarching goal is to improve the understanding of phenomena that take place during low temperature black liquor gasification. This is achieved through five complementary technical tasks: (1) construction of a fluidized bed black liquor gasification test system, (2) investigation of bed performance, (3) evaluation of product gas quality, (4) black liquor conversion analysis and modeling and (5) computational modeling of the Big Island gasifier. Four experimental devices have been constructed under this project. The largest facility, which is the heart of the experimental effort, is a pressurized fluidized bed gasification test system. The system is designed to be able to reproduce conditions near the black liquor injectors in the Big Island steam reformer, so the behavior of black liquor pyrolysis and char gasification can be quantified in a representative environment. The gasification test system comprises five subsystems: steam generation and superheating, black liquor feed, fluidized bed reactor, afterburner for syngas combustion and a flue gas cooler/condenser. The three-story system is located at University of Utah's Industrial Combustion and Gasification Research Facility, and all resources there are available to support the research.

  12. Archimedes' principle in fluidized granular systems.

    Science.gov (United States)

    Huerta, D A; Sosa, Victor; Vargas, M C; Ruiz-Suárez, J C

    2005-09-01

    We fluidize a granular bed in a rectangular container by injecting energy through the lateral walls with high-frequency sinusoidal horizontal vibrations. In this way, the bed is brought to a steady state with no convection. We measured buoyancy forces on light spheres immersed in the bed and found that they obey Archimedes' principle. The buoyancy forces decrease when we reduce the injected energy. By measuring ascension velocities as a function of gamma, we can evaluate the frictional drag of the bed; its exponential dependence agrees very well with previous findings. Rising times of the intruders ascending through the bed were also measured, they increase monotonically as we increase the density.

  13. Fluidized bed adsorption of cephalosporin C.

    Science.gov (United States)

    Hicketier, M; Buchholz, K

    2002-02-28

    Fluidized bed adsorption can substantially simplify the recovery of products from fermentation. There are, however, several critical parameters, which have a significant influence on the performance of such systems. This paper presents experimental results on the adsorption of an antibiotic, Cephalosporin C, on macroporous adsorbents of the polystyrene type and on an ion exchanger. Internals (static mixers) were used to control bed expansion and mixing, the range of flow rates could thus be extended significantly. An integrated mathematical model was developed comprising bed expansion, residence time distribution and mixing, adsorption kinetics and equilibria.

  14. Nucla circulating atmospheric fluidized bed demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-31

    During the fourth quarter of 1990, steady-state performance testing at the Nucla Circulating Fluidized Bed (CFB) resumed under sponsorship of the US Department of Energy. Co-sponsorship of the Demonstration Test Program by the Electric Power Research Institute (EPRI) was completed on June 15, 1990. From October through December, 1990, Colorado-Ute Electric Association (CUEA) completed a total of 23 steady-state performance tests, 4 dynamic tests, and set operating records during November and December as the result of improved unit operating reliability. Highlight events and achievements during this period of operation are presented.

  15. Electrostatic collection efficiency in binary fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Romero, A.; Guardiola, J.; Rincon, J. (Univ. of Alcala de Henares, Madrid (Spain))

    1992-01-01

    Fluidized beds of binary mixtures have been used to clean air streams containing dust particles in the size range 4.4 to 14 {mu}m. All beds were composed of glass beads and plastic granules mixed at different proportions. The effect on the electrostatic collection efficiency of a number of variables, including type of collecting mixture, bed height, and gas velocity, was examined. To calculate the single collection efficiency from experimental results, an early model proposed by Clift et al. was used. The electrostatic collection efficiency was determined by subtracting the other individual mechanism efficiencies from the single particle collection efficiency.

  16. Pyrolysis reactor and fluidized bed combustion chamber

    Science.gov (United States)

    Green, Norman W.

    1981-01-06

    A solid carbonaceous material is pyrolyzed in a descending flow pyrolysis reactor in the presence of a particulate source of heat to yield a particulate carbon containing solid residue. The particulate source of heat is obtained by educting with a gaseous source of oxygen the particulate carbon containing solid residue from a fluidized bed into a first combustion zone coupled to a second combustion zone. A source of oxygen is introduced into the second combustion zone to oxidize carbon monoxide formed in the first combustion zone to heat the solid residue to the temperature of the particulate source of heat.

  17. Pluto: Fluidized Transport of Tholins by Heating of the Subsurface

    Science.gov (United States)

    Cruikshank, Dale P.; Spohrer, Steven; Grundy, William M.; Moore, Jeffrey M.; Umurhan, Orkan M.; White, Oliver L.; Beyer, Ross A.; Dalle Ore, Cristina M.; Stern, S. A.; Young, Leslie; hide

    2017-01-01

    New Horizons images of Pluto show evidence of the transport of the colored non-ice component across the surface, with substantial accumulations in some areas of low elevation. The non-ice component is presumed to be tholin produced in the atmosphere as a precipitating aerosol, in the surface ices by photolysis or radiolysis, or both. We model the surface layer of N2 ice with varying amounts of incorporated tholin particles to explore the heating within the ice that occurs by the solid-state greenhouse effect. We find that in plausible models of the contaminated N2 surface ice the triple point temperature (63.15K) is reached at a depth of approximately less than 1m. At that depth the confining pressure of the ice column is much less than the triple point pressure (12.52 kPa), so N2 should convert to the gas phase, exerting pressure on the overburden. When the gas pressure exceeds the strength of the confining ice, a breakout on the surface will occur, fluidizing fragments of ice and its contaminants that are then free to flow downhill, rafted on entrained gas, similar in some ways to the pyroclastic volcanic phenomenon known as nuée ardente. The digital elevation map of Pluto made from stereo images shows some surface regions that may have been stripped of the N2 layer, exposing H2O ice (presumed to be bedrock) below, with a corresponding accumulation of dark material that was that was the previously entrained particulate tholin. Accumulations of tholin are found associated with some of the fossae, and some cover preexisting topography to depths of up to a few hundred meters.

  18. Database implementation to fluidized cracking catalytic-FCC process

    International Nuclear Information System (INIS)

    Santana, Antonio Otavio de; Dantas, Carlos Costa; Santos, Valdemir A. dos

    2009-01-01

    A process of Fluidized Cracking Catalytic (FCC) was developed by our research group. A cold model FCC unit, in laboratory scale, was used for obtaining of the data relative to the following parameters: air flow, system pressure, riser inlet pressure, rise outlet pressure, pressure drop in the riser, motor speed of catalyst injection and density. The measured of the density is made by gamma ray transmission. For the fact of the process of FCC not to have a database until then, the present work supplied this deficiency with the implementation of a database in connection with the Matlab software. The data from the FCC unit (laboratory model) are obtained as spreadsheet of the MS-Excel software. These spreadsheets were treated before importing them as database tables. The application of the process of normalization of database and the analysis done with the MS-Access in these spreadsheets treated revealed the need of an only relation (table) for to represent the database. The Database Manager System (DBMS) chosen has been the MS-Access by to satisfy our flow of data. The next step was the creation of the database, being built the table of data, the action query, selection query and the macro for to import data from the unit FCC in study. Also an interface between the application 'Database Toolbox' (Matlab2008a) and the database was created. This was obtained through the drivers ODBC (Open Data Base Connectivity). This interface allows the manipulation of the database by the users operating in the Matlab. (author)

  19. A case of home care of a 103-year-old patient with Alzheimer’ s disease complicated with stage III pressure ulcer

    Directory of Open Access Journals (Sweden)

    Zheng Wang

    2017-04-01

    Full Text Available This paper reported a case of home care for a 103-year-old AD patient with stage III pressure ulcers. After ten weeks of professional home care, including the guidance for caregivers, such as posture putting, wound decompression, nutritional support, clinical nurse specialist come to home to give wound assessment and care, the ulcer was eventually healed. It is suggested that for the senior AD patients, intelligent auxiliary equipment can be introduced into the family in the future, it can help reduce the pressure of the affected side, reduce the burden on caregivers, meanwhile, wound specialist nurses came to the caregiver to give systemic instructions, prevent the occurrence and development of pressure ulcers.

  20. Next generation fluidized bed granulator automation.

    Science.gov (United States)

    Rantanen, J; Känsäkoski, M; Suhonen, J; Tenhunen, J; Lehtonen, S; Rajalahti, T; Mannermaa, J P; Yliruusi, J

    2000-05-06

    A system for fluidized bed granulator automation with in-line multichannel near infrared (NIR) moisture measurement and a unique air flow rate measurement design was assembled, and the information gained was investigated. The multivariate process data collected was analyzed using principal component analysis (PCA). The test materials (theophylline and microcrystalline cellulose) were granulated and the calibration behavior of the multichannel NIR set-up was evaluated against full Fourier Transform (FT) NIR spectra. Accurate and reliable process air flow rate measurement proved critical in controlling the granulation process. The process data describing the state of the process was projected in two dimensions, and the information from various trend charts was outlined simultaneously. The absorbence of test material at correction wavelengths (NIR region) and the nature of material-water interactions affected the detected in-line NIR water signal. This resulted in different calibration models for the test materials. Development of process analytical methods together with new data visualization algorithms creates new tools for in-process control of the fluidized bed granulation.

  1. Fluidized bed gasification of select granular biomaterials.

    Science.gov (United States)

    Subramanian, P; Sampathrajan, A; Venkatachalam, P

    2011-01-01

    Biomaterials can be converted into solid, liquid and gaseous fuels through thermochemical or biochemical conversion processes. Thermochemical conversion of granular biomaterials is difficult because of its physical nature and one of the suitable processes is fluidized bed gasification. In this study, coir pith, rice husk and saw dust were selected and synthetic gas was generated using a fluidized bed gasifier. Gas compositions of product gas were analyzed and the percentage of carbon monoxide and carbon dioxide was in the range of 8.24-19.55 and 10.21-17.14, respectively. The effect of equivalence ratio (0.3, 0.4 and 0.5) and reaction time (at 10 min interval) on gas constituents was studied. The gas yield for coir pith, rice husk and sawdust were found to be in the range of 1.98-3.24, 1.79-2.81 and 2.18-3.70 Nm3 kg(-1), respectively. Models were developed to study the influence of biomaterial properties and operating conditions on molar concentration of gas constituents and energy output. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Rocky Flats Plant fluidized-bed incinerator

    International Nuclear Information System (INIS)

    Meile, L.J.; Meyer, F.G.; Johnson, A.J.; Ziegler, D.L.

    1982-01-01

    Laboratory and pilot-scale testing of a fluidized-bed incineration process for radioactive wastes led to the installation of an 82-kg/hr demonstration unit at Rocky Flats Plant in 1978. Design philosophy and criteria were formulated to fulfill the needs and objectives of an improved radwaste-incineration system. Unique process concepts include low-temperature (550 0 C), flameless, fluidized-bed combustion and catalytic afterburning; in-situ neutralization of acid gases; and dry off-gas cleanup. Detailed descriptions of the process and equipment are presented along with a summary of the equipment and process performance during a 2-1/2 year operational-testing period. Equipment modifications made during the test period are described. Operating personnel requirements for solid-waste burning are shown to be greater than those required for liquid-waste incineration; differences are discussed. Process-utility and raw-materials consumption rates for full-capacity operation are presented and explained. Improvements in equipment and operating procedures are recommended for any future installations. Process flow diagrams, an area floor plan, a process-control-system schematic, and equipment sketches are included

  3. Daily blueberry consumption improves blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension: a randomized, double-blind, placebo-controlled clinical trial.

    Science.gov (United States)

    Johnson, Sarah A; Figueroa, Arturo; Navaei, Negin; Wong, Alexei; Kalfon, Roy; Ormsbee, Lauren T; Feresin, Rafaela G; Elam, Marcus L; Hooshmand, Shirin; Payton, Mark E; Arjmandi, Bahram H

    2015-03-01

    Postmenopausal women have a high prevalence of hypertension and often develop arterial stiffness thereby increasing cardiovascular disease risk. Although antihypertensive drug therapies exist, increasing numbers of people prefer natural therapies. In vivo studies and a limited number of clinical studies have demonstrated the antihypertensive and vascular-protective effects of blueberries. To examine the effects of daily blueberry consumption for 8 weeks on blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension. This was an 8-week, randomized, double-blind, placebo-controlled clinical trial. Forty-eight postmenopausal women with pre- and stage 1-hypertension recruited from the greater Tallahassee, FL, area participated. Participants were randomly assigned to receive either 22 g freeze-dried blueberry powder or 22 g control powder. Resting brachial systolic and diastolic blood pressures were evaluated and arterial stiffness was assessed using carotid-femoral pulse wave velocity and brachial-ankle pulse wave velocity. C-reactive protein, nitric oxide, and superoxide dismutase were measured at baseline, 4 weeks, and 8 weeks. Statistical analysis was performed using a split plot model of repeated measures analysis of variance. After 8 weeks, systolic blood pressure and diastolic blood pressure (131±17 mm Hg [Pblueberry powder group, whereas there were no changes in the group receiving the control powder. Nitric oxide levels were greater (15.35±11.16 μmol/L; Pblueberry powder group at 8 weeks compared with baseline values (9.11±7.95 μmol/L), whereas there were no changes in the control group. Daily blueberry consumption may reduce blood pressure and arterial stiffness, which may be due, in part, to increased nitric oxide production. Copyright © 2015 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  4. Morphology of {gamma}' precipitates of nickel-based superalloy serviced as first stage high pressure turbine nozzle guide vane

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Nobuhiro; Nakada, Kouji; Kondo, Yoshihiro [National Defense Academy, Yokosuka, Kanagawa (Japan)

    2010-07-01

    The morphology of {gamma}' precipitates of the nickel-based superalloy serviced as the first stage high pressure turbine nozzle guide vane of the jet engine was examined. The aim of this work was to estimate the temperature and the stress distribution, and the stress direction of the vane in service. The vane was cut into four parts perpendicular to the longitudinal direction of the vane at 5, 25, 35 and 45mm from the root. These parts were designated as the root, 25mm, 35mm and tip parts. Microstructure observations by a FE-SEM were carried out on the forty-six portions at the vicinity of the interface between the coating layer and the matrix on the suction and pressure sides. At the root parts of the pressure and suction sides, most of the {gamma}' precipitates kept cuboidal in shape, and the secondary {gamma}' precipitates were observed in the {gamma} matrix channels. On the contrary, at the trailing edge side of the pressure and suction sides of the 25 and 35mm parts and at the leading edge of the pressure side of the tip part, well aligned rafted {gamma}/{gamma}' structures were appeared in the direction parallel to the surface at the vicinity of the interface of the vane. Furthermore, at the trailing edge of the pressure side of the middle parts, the rafted {gamma}/{gamma}' structures start to collapse. Consequently, the vane in service, at the trailing edge sides of the pressure side the 25 and 35mm parts were exposed to the highest temperature and stress conditions. And this microstructure evidence indicated that the multi-axial compressive stress parallel to the nozzle surface was expected to act on the vane in service. (orig.)

  5. The construction and uses of factorial designs in the preparation of solid dosage forms. Part 2: Granulation in a fluidized bed.

    Science.gov (United States)

    Gorodnichev, V I; El-Banna, H M; Andreev, B V

    1981-04-01

    With the help of a factorial design of experiments, the optimum conditions for preparing aminophenazone granules in a fluidized bed were established by which high quality tablets were obtained with a minimum energy expenditure. Granules with given technological properties could be prepared by controlling the regime of the granulation process. By varying the experimental conditions, a reproducible correlation was found between the parameters of optimization (mean granule diameter and work of compression) and the factors controlling the granulation process (pressure of compressed air, velocity and temperature of fluidizing air and binder concentration). The effect of the granule quality on tablet physical properties was discussed. Recommendations were given for the exploitation of fluidized bed units in the practice of granulation and tableting.

  6. High pressure measurement of the uniaxial stress of host layers on intercalants and staging transformation of intercalation compounds

    CERN Document Server

    Park, T R; Kim, H; Min, P

    2002-01-01

    A layered double-hydroxide intercalation compound was synthesized to measure the uniaxial stress the host layers exert on the intercalants. To measure the uniaxial stress, we employed the photoluminescence (PL) from the intercalated species, the Sm ion complex, as it is sensitive to the deformation of the intercalants. Of the many PL peaks the Sm ion complex produces, the one that is independent of the counter-cation environment was chosen for the measurement since the Sm ion complexes are placed under a different electrostatic environment after intercalation. The peak position of the PL was redshifted linearly with increasing hydrostatic pressure on the intercalated sample. Using this pressure-induced redshifting rate and the PL difference at ambient pressure between the pre-intercalation and the intercalated ions, we found that, in the absence of external pressure, the uniaxial stress exerted on the samarium ion complexes by the host layers was about 13.9 GPa at room temperature. Time-resolved PL data also ...

  7. Modern fluidized bed combustion in Ostrava-Karvina cogeneration plants

    Energy Technology Data Exchange (ETDEWEB)

    Mazac, V. [Energoprojekt Praha, Ostrava (Czechoslovakia); Novacek, A. [Moravskoslezske teplamy, Ostrava (Czechoslovakia); Volny, J. [Templamy Karvina (Czechoslovakia)

    1995-12-01

    The contemporary situation of our environment claims the sensitive approach to solving effective conversion of energy. Limited supplies of noble fuels and their prices evoke the need to use new combustion technologies of accessible fuels in given region without negative ecological influences. Energoproject participates in the preparation of the two projects in Ostrava-Karvin{acute a} black coal field in Czech Republic. The most effective usage of fuel energy is the combined of electricity and heat. If this physical principle is supported by a pressurized fluidized bed combustion (PFBC) one obtains a high electricity/heat ratio integrated steam-gas cycle on the basis of solid fuel. Cogeneration plant Toebovice is the dominant source (600 MW{sub th}) of Ostrava district heating system (1100 MW{sub th}). The high utilization of the installed output and utilization of the clean, compact and efficient of the PFBC technology is the principal but not the single reason for the selection of the Toebovice power plant as the first cogeneration plant for installation of the PFBC in Czech Republic. The boiler will burn black coal from the neighboring coal basin.

  8. Ash behavior and de-fluidization in low temperature circulating fluidized bed biomass gasifier

    DEFF Research Database (Denmark)

    Narayan, Vikas

    at Risø and a 6 MW LTCFB gasifier owned by DONG ENERGY and placed in Kalundborg. In addition to the analysis of the inorganic elemental composition of the collected samples, SEM and TGA analysis of the samples were made to improve understanding on the behavior of the ash forming species within the system...... the bed particle diameters and the fraction of K entrained from the system. The model was also applied to study the de-fluidization behavior of alkali-rich samples in a large scale LTCFB gasifier. The model was used to predict the variations in de-fluidization time on a full scale LTCFB plant with respect...... ensures that high-alkali biomass fuels can be used without risks of bed de-fluidization. This thesis aims to understand the behavior of alkali metals and ash in the LTCFB system. The thesis work involved measurements made on bed material and product gas dust samples on a 100kW LTCFB gasifier placed...

  9. Heat transfer to immersed horizontal tubes in gas fluidized bed dryers

    Energy Technology Data Exchange (ETDEWEB)

    Jonassen, Ola

    1999-07-01

    The main objective of this study was to construct heat pump fluidized bed dryers of the FHT type with improved dewatering capacity for a given size of the dryer. The use of heat exchangers immersed in the fluidized bed drying chambers is an important part of the FHT (Fluidized Bed High Temperature Heat Pump Dryer) concept. A pilot plant FHT dryer was built and successfully tested on fish meal raw material and seaweed. The plant included two fluidized bed drying chambers with immersed heat exchangers. The gain in water vapor of the drying air through the chambers was increased up to four times that of adiabatic drying. The energy saving concept was retained as a SMER ratio of 3.5 to 4.7 was measured in the same tests. Therefore optimization of the immersed heat exchangers was considered the most important single objective for this work. The optimization study of the heat exchangers was confined to the actual operating conditions for the dryers using: (1) Bubbling gas fluidized beds were used, (2) air as the only type of fluidizing gas,(3) beds at atmospheric pressure, (4) bed temperatures below 100 {sup o}C, (5) fluidized particles of Geldart classes B and D, (6) horizontal tube banks for the immersed heat exchanger and the influence of radiation heat transfer was ignored. The heat transfer study was confined to the fluidized bed side of the heat exchanger surface. It was concluded early in this work that the bubbles play a major role in generating the particle circulation inside the bed and hence also in heat transfer. Publications describing the most important bubble induced mechanisms contributing to high rates of heat transfer were found to be limited. Therefore the first part of this study was aimed at establishing a method for locating and measuring the size and rise velocity of bubbles inside the bed. The method established through this work using differential pressure measurements from two static pressure probes was used later in the study of heat transfer

  10. Fluidized Bed Membrane Reactors for Ultra Pure H2 Production—A Step forward towards Commercialization

    Directory of Open Access Journals (Sweden)

    Arash Helmi

    2016-03-01

    Full Text Available In this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm3/h of ultra-pure H2 was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H2 partial pressure differences. The membranes showed very high H2 fluxes (3.89 × 10−6 mol·m−2·Pa−1·s−1 at 400 °C and 1 atm pressure difference with a H2/N2 ideal perm-selectivity (up to 21,000 when integrating five membranes in the module beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average <10 ppm, so that the produced hydrogen can be directly fed to a low temperature PEM fuel cell.

  11. Fluidized Bed Membrane Reactors for Ultra Pure H₂ Production--A Step forward towards Commercialization.

    Science.gov (United States)

    Helmi, Arash; Fernandez, Ekain; Melendez, Jon; Pacheco Tanaka, David Alfredo; Gallucci, Fausto; van Sint Annaland, Martin

    2016-03-19

    In this research the performance of a fluidized bed membrane reactor for high temperature water gas shift and its long term stability was investigated to provide a proof-of-concept of the new system at lab scale. A demonstration unit with a capacity of 1 Nm³/h of ultra-pure H₂ was designed, built and operated over 900 h of continuous work. Firstly, the performance of the membranes were investigated at different inlet gas compositions and at different temperatures and H₂ partial pressure differences. The membranes showed very high H₂ fluxes (3.89 × 10(-6) mol·m(-2)·Pa(-1)·s(-1) at 400 °C and 1 atm pressure difference) with a H₂/N₂ ideal perm-selectivity (up to 21,000 when integrating five membranes in the module) beyond the DOE 2015 targets. Monitoring the performance of the membranes and the reactor confirmed a very stable performance of the unit for continuous high temperature water gas shift under bubbling fluidization conditions. Several experiments were carried out at different temperatures, pressures and various inlet compositions to determine the optimum operating window for the reactor. The obtained results showed high hydrogen recovery factors, and very low CO concentrations at the permeate side (in average hydrogen can be directly fed to a low temperature PEM fuel cell.

  12. The Rheology of Acoustically Fluidized Sand

    Science.gov (United States)

    Conrad, J. W.; Melosh, J.

    2013-12-01

    The collapse of large craters and the formation of central peaks and peak rings is well modeled by numerical computer codes that incorporate the acoustic fluidization mechanism to temporarily allow the fluid-like flow of rock debris immediately after crater excavation. Furthermore, long runout landslides require a similar mechanism to explain their almost frictionless movement, which is probably also a consequence of their granular composition coupled with internal vibrations. Many different investigators have now confirmed the ability of vibrations to fluidize granular materials. Yet it still remains to fully describe the rheology of vibrated sand as a function of stress, frequency and amplitude of the vibrations in the sand itself. We constructed a rotational viscometer to quantitatively investigate the relation between the stress and strain rate in a horizontal bed of strongly vibrated sand. In addition to the macroscopic stain rate, the amplitude and frequency of the vibrations produced by a pair of pneumatic vibrators were also measured with the aid of miniaturized piezoelectric accelerometers (B&K 4393) whose output was recorded on a digital storage oscilloscope. The initial gathering of the experimental data was difficult due to granular memory, but by having the sand compacted vibrationally for 8 minutes before each run the scatter of data was reduced and we were able to obtain consistent results. Nevertheless, our major source of uncertainty was variations in strain rate from run to run. We find that vibrated sand flows like a highly non-Newtonian fluid, in which the shear strain rate is proportional to stress to a power much greater than one, where the precise power depends on the amplitude and frequency of the applied vibrations. Rapid flow occurs at stresses less than half of the static yield stress (that is, the yield stress when no vibration is applied) when strong vibrations are present. For a Newtonian fluid, such as water, the relation between

  13. Dust removal from waste gas arising from fluidized beds

    International Nuclear Information System (INIS)

    Soltys, L.

    1992-01-01

    Two types dust removal equipment mostly useful for dust removal from waste gas from fluidized beds, i.e. electrofilters and pulsatory bag filters were presented. Their features and functional properties were compared. (author). 7 refs, 4 figs

  14. Synthesis of carbon nanotubes using fluidized bed technology

    CSIR Research Space (South Africa)

    Swartbooi, AM

    2008-11-01

    Full Text Available virgin plastics as well as a carbonaceous gas using fluidized bed technology. Current investigations are underway to test various factors involved with the CNT growth and production. An understanding of these factors and their interactions could provide...

  15. Nucla circulating atmospheric fluidized bed demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    Keith, Raymond E.

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute's decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  16. Fluid dynamic study of a new type of solid-gas contactor: the fluidized/fixed or fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Bilbao, R.

    1982-10-01

    A fluid dynamic study of a new type of solid-gas contactor has been realized. This contactor consists of a fluidized bed with a considerable enlargement of the cross section of its upper zone. This enlargement of section results in a reduction of the gas velocity in the upper zone, with a subsequent bubbling diminution. Experiments have been performed varying the scale of the contactor, its geometry, the relation between the cross sections of the upper and lower zones of the contactor, the solid height in the upper zone, and the density and size of the solid. The study has been centered on the contactor behavior with variation of the inlet gas velocity, on the bubble size distribution along the contactor, on the determination of the gas pressure drop in the whole contactor and in each zone of the bed, and on the calculation of the gas velocities modifying the state of the contactor (u /SUB r/, u /SUB c/, u /SUB mf/).

  17. Fluidized Bed Sputtering for Particle and Powder Metallization

    Science.gov (United States)

    2013-04-01

    Sathiyamoorthy provides a review of plasma technology used with fluidized bed techniques (13). Borer and von Rohr integrated a microwave plasma source...Plasma Spouted/Fluidized Bed for Materials Processing. Journal of Physics: Conference Series 2010, 208 (1), 012120. 14. Borer, B.; von Rohr , R...Technology 2005, 200, 377–381. 15. Morstein, M.; Karches, M.; Bayer, C.; Casanova, D.; von Rohr , P. R. Plasma CVD of Ultrathin TiO2 Films on Powders in a

  18. Fluidized-bed calciner with combustion nozzle and shroud

    International Nuclear Information System (INIS)

    Wielang, J.A.; Palmer, W.B.; Kerr, W.B.

    1977-01-01

    A nozzle employed as a burner within a fluidized bed is coaxially enclosed within a tubular shroud that extends beyond the nozzle length into the fluidized bed. The open-ended shroud portion beyond the nozzle end provides an antechamber for mixture and combustion of atomized fuel with an oxygen-containing gas. The arrangement provides improved combustion efficiency and excludes bed particles from the high-velocity, high-temperature portions of the flame to reduce particle attrition. 4 claims, 2 figures

  19. Chebyshev super spectral viscosity method for a fluidized bed model

    International Nuclear Information System (INIS)

    Sarra, Scott A.

    2003-01-01

    A Chebyshev super spectral viscosity method and operator splitting are used to solve a hyperbolic system of conservation laws with a source term modeling a fluidized bed. The fluidized bed displays a slugging behavior which corresponds to shocks in the solution. A modified Gegenbauer postprocessing procedure is used to obtain a solution which is free of oscillations caused by the Gibbs-Wilbraham phenomenon in the spectral viscosity solution. Conservation is maintained by working with unphysical negative particle concentrations

  20. Chebyshev super spectral viscosity method for a fluidized bed model

    CERN Document Server

    Sarra, S A

    2003-01-01

    A Chebyshev super spectral viscosity method and operator splitting are used to solve a hyperbolic system of conservation laws with a source term modeling a fluidized bed. The fluidized bed displays a slugging behavior which corresponds to shocks in the solution. A modified Gegenbauer postprocessing procedure is used to obtain a solution which is free of oscillations caused by the Gibbs-Wilbraham phenomenon in the spectral viscosity solution. Conservation is maintained by working with unphysical negative particle concentrations.

  1. Numerical simulations of the industrial circulating fluidized bed boiler under air- and oxy-fuel combustion

    International Nuclear Information System (INIS)

    Adamczyk, Wojciech P.; Kozołub, Paweł; Klimanek, Adam; Białecki, Ryszard A.; Andrzejczyk, Marek; Klajny, Marcin

    2015-01-01

    Measured and numerical results of air-fuel combustion process within large scale industrial circulating fluidized bed (CFB) boiler is presented in this paper. For numerical simulations the industrial compact CFB boiler was selected. Numerical simulations were carried out using three-dimensional model where the dense particulate transport phenomenon was simultaneously modelled with combustion process. The fluidization process was modelled using the hybrid Euler-Lagrange approach. The impact of the geometrical model simplification on predicted mass distribution and temperature profiles over CFB boiler combustion chamber two kinds of geometrical models were used, namely the complete model which consist of combustion chamber, solid separators, external solid super-heaters and simplified boiler geometry which was reduced to the combustion chamber. The evaluated temperature and pressure profiles during numerical simulations were compared against measured data collected during boiler air-fuel operation. Collected data was also used for validating numerical model of the oxy-fuel combustion model. Stability of the model and its sensitivity on changes of several input parameters were studied. The comparison of the pressure and temperature profiles for all considered cases gave comparable trends in contrary to measured data. Moreover, some additional test was carried out the check the influence of radiative heat transfer on predicted temperature profile within the CFB boiler. - Highlights: • Hybrid Euler-Lagrange approach was used for modelling particle transport, air- and oxy-fuel combustion process. • Numerical results were validated against measured data. • The influence of different boiler operating conditions on calculated temperature profile was investigated. • New strategy for resolving particle transport in circulating fluidized bed was shown

  2. Pulsed atmospheric fluidized bed combustion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  3. The Impact of Hemodialysis Frequency and Duration on Blood Pressure Management and Quality of Life in End-Stage Renal Disease Patients

    Science.gov (United States)

    Shafiee, Mohammad Ali; Chamanian, Pouyan; Shaker, Pouyan; Shahideh, Yasmin; Broumand, Behrooz

    2017-01-01

    Cardiovascular complications are the most prominent causes of morbidity and mortality among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients undergoing standard hemodialysis (HD) therapy. Cardiovascular disease risk is increased significantly through persistent hypertension and blood pressure (BP) fluctuation, which are the most common complications of CKD. It was hypothesized that an extended approach with lengthier and more frequent dialysis sessions, referred to in this paper as “extended hemodialysis” (EHD), can potentially lower and stabilize blood pressure, and consequently reduce the rate of morbidity and mortality. A greater reduction of volume (salt and water) with higher frequency can improve patient quality of life (QOL). Eleven papers, including clinical trials and systematic reviews were chosen and analyzed. The extracted data was used to evaluate the change in blood pressure levels between standard HD and EHD. Overall, the studies showed that EHD resulted in improved blood pressure management; therefore, we concluded that there will be a decrease in cardiovascular disease risk, stroke, and morbidity and mortality rate. There will be also an improvement in patient QOL due to beneficial effects of the EHD. PMID:28869490

  4. An Experimental Investigation of the Flow Physics Associated With End Wall Losses and Large Rotor Tip Clearances as Found in the Rear Stages of a High Pressure Compressor

    Science.gov (United States)

    Berdanier, Reid A.; Key, Nicole L.

    2015-01-01

    The focus of this work was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearance heights were studied with nominal tip clearance heights of 1.5%, 3.0%, and 4.0% based on a constant annulus height. Overall compressor performance was investigated at four corrected speedlines (100%, 90%, 80%, and 68%) for each of the three tip clearance configurations using total pressure and total temperature rakes distributed throughout the compressor. The results have confirmed results from previous authors showing a decrease of total pressure rise, isentropic efficiency, and stall margin which is approximately linear with increasing tip clearance height. The stall inception mechanisms have also been evaluated at the same corrected speeds for each of the tip clearance configurations. Detailed flow field measurements have been collected at two loading conditions, nominal loading (NL) and high loading (HL), on the 100% corrected speedline for the smallest and largest tip clearance heights (1.5% and 4.0%). Steady detailed radial traverses of total pressure at the exit of each stator row have been supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data have helped to quantify the size of the leakage flow at the exit of each rotor. Thermal anemometry has also been implemented to evaluate the time-resolved three-dimensional components of velocity throughout the compressor and calculate blockage due to the rotor tip leakage flow throughout the compressor. These

  5. Verification of an altitude decompression sickness prevention protocol for Shuttle operations utilizing a 10.s psi pressure stage

    Science.gov (United States)

    Waligora, J. M.; Horrigan, D. J., Jr.; Conkin, J.; Hadley, A. T., III

    1984-01-01

    Three test series involving 173-man tess were conducted to define and verify a pre-extravehicular activity (EVA) denitrogenation procedure that would provide acceptable protection against altitude decompression sickness while minimizing the required duration of oxygen (O2) prebreathe in the suit prior to EVA. The tests also addressed the safety, in terms of incidence of decompression sickness, of conducting EVA's on consecutive days rather than on alternate days. The tests were conducted in an altitude chamber, subjects were selected as representative of the astronaut population, and EVA periods were simulated by reducing the chamber pressure to suit pressure while the subjects breathed O2 with masks and worked at EVA representative work rates. A higher than anticipated incidence of both venous bubbles (55%) and symptoms (26%) was measured following all denitrogenation protocols in this test. For the most part, symptoms were very minor and stabilized, diminished, or disappeared in the six-hour tests. Instances of clear, possible, or potential systemic symptoms were encountered only after use of the unmodified 10.2 psi protocol and not after the modified 10.2 psi protocol, the 3.5-hour O2 prebreathed protocol, or the 4.0-hour O2 prebreathe protocol. The high incidence of symptoms is ascribed to the type and duration of exercise and the sensitivity of the reporting technique to minor symptoms. Repeated EVA exposures after only 17 hours did not increase symptom or bubble incidence.

  6. Heat transfer to immersed horizontal tubes in gas fluidized bed dryers

    Energy Technology Data Exchange (ETDEWEB)

    Jonassen, Ola

    1999-10-01

    The main objective of this study was to construct heat pump fluidized bed dryers of the FHT type with improved dewatering capacity for a given size of the dryer. The use of heat exchangers immersed in the fluidized bed drying chambers is an important part of the FHT (Fluidized Bed High Temperature Heat Pump Dryer) concept. A pilot plant FHT dryer was built and successfully tested on fish meal raw material and seaweed. The plant included two fluidized bed drying chambers with immersed heat exchangers. The gain in water vapor of the drying air through the chambers was increased up to four times that of adiabatic drying. The energy saving concept was retained as a SMER ratio of 3.5 to 4.7 was measured in the same tests. Therefore optimization of the immersed heat exchangers was considered the most important single objective for this work. The optimization study of the heat exchangers was confined to the actual operating conditions for the dryers using: (1) Bubbling gas fluidized beds were used, (2) air as the only type of fluidising gas, (3) beds at atmospheric pressure, (4) bed temperatures below 100 {sup o}C, (5) fluidized particles of Geldart classes B and D, (6) horizontal tube banks for the immersed heat exchanger, and the influence of radiation heat transfer was ignored. The heat transfer study was confined to the fluidized bed side of the heat exchanger surface. It was concluded early in this work that the bubbles play a major role in generating the particle circulation inside the bed and hence also in heat transfer. Publications describing the most important bubble induced mechanisms contributing to high rates of heat transfer were found to be limited. Therefore the first part of this study was aimed at establishing a method for locating and measuring the size and rise velocity of bubbles inside the bed. The method established through this work using differential pressure measurements from two static pressure probes was used later in the study of heat transfer

  7. Experimental study of biomass gasification with oxygen-enriched air in fluidized bed gasifier.

    Science.gov (United States)

    Liu, Lingqin; Huang, Yaji; Cao, Jianhua; Liu, Changqi; Dong, Lu; Xu, Ligang; Zha, Jianrui

    2018-06-01

    Considering the universality, renewability and cleanness of biomass, an experimental research is carried out using rice straw in a two-stage fluidized bed. The experimental analysis identified the relevant parameters in the operation of the two-stage fluidized bed to investigate the properties of biomass enriched air gasification. Results show that higher gasification temperature is conducive to enhance the gasification performance. An increasing ER is shown to go against adding gas heat value. When oxygen concentration increases from 21% to 45%, the gas heating value increases from 4.00MJ/kg to 5.24MJ/kg and the gasification efficiency increases from 29.60% to 33.59%, which shows higher oxygen concentration is conducive to higher quality gas and higher gasification efficiency. A secondary oxygen injection leads to reduction of tar concentration from 15.78g/Nm 3 to 10.24g/Nm 3 . The optimal secondary oxygen ratio is about 33.00%. When the secondary oxygen ratio increased to 46.86%, monocyclic aromatics reduced from 28.17% to 19.65% and PAHs increased from 34.97% to 44.05%, leading to the increase aromatization of tar. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Iyengar Yoga versus Enhanced Usual Care on Blood Pressure in Patients with Prehypertension to Stage I Hypertension: a Randomized Controlled Trial.

    Science.gov (United States)

    Cohen, Debbie L; Bloedon, Leanne T; Rothman, Rand L; Farrar, John T; Galantino, Mary Lou; Volger, Sheri; Mayor, Christine; Szapary, Phillipe O; Townsend, Raymond R

    2011-01-01

    The prevalence of prehypertension and Stage 1 hypertension continues to increase despite being amenable to non-pharmacologic interventions. Iyengar yoga (IY) has been purported to reduce blood pressure (BP) though evidence from randomized trials is lacking. We conducted a randomized controlled trial to assess the effects of 12 weeks of IY versus enhanced usual care (EUC) (based on individual dietary adjustment) on 24-h ambulatory BP in yoga-naïve adults with untreated prehypertension or Stage 1 hypertension. In total, 26 and 31 subjects in the IY and EUC arms, respectively, completed the study. There were no differences in BP between the groups at 6 and 12 weeks. In the EUC group, 24-h systolic BP (SBP), diastolic BP (DBP) and mean arterial pressure (MAP) significantly decreased by 5, 3 and 3 mmHg, respectively, from baseline at 6 weeks (P IY group, 24 h SBP was reduced by 6 mmHg at 12 weeks compared to baseline (P = .05). 24 h DBP (P IY group at 12 weeks. Twelve weeks of IY produces clinically meaningful improvements in 24 h SBP and DBP. Larger studies are needed to establish the long term efficacy, acceptability, utility and potential mechanisms of IY to control BP.

  9. Single Crystal Casting with Fluidized Carbon Bed Cooling: A Process Innovation for Quality Improvement and Cost Reduction

    Science.gov (United States)

    Hofmeister, M.; Franke, M. M.; Koerner, C.; Singer, R. F.

    2017-12-01

    Superalloy gas turbine blades are being produced by investment casting and directional solidification. A new process, Fluidized Carbon Bed Cooling (FCBC), has been developed and is now being optimized in a prototype casting unit with 10 kg pouring weight. In early test runs with still rather simple mold cluster geometries, a reduction of the primary dendrite arm spacing of around 40 pct compared to the standard radiation cooling process (HRS) could be demonstrated. The improvement is mainly attributed to higher temperature gradients driving solidification, made possible by a functioning Dynamic Baffle. Compared to earlier development efforts in the literature, contamination of the melt and damage to the equipment are avoided using carbon-based fluidized bed materials and the so-called "counter pressure concept."

  10. Phase Holdups in A Three-Phase Fluidized Bed in the Presence of Coaxially Placed String of Spheres Internal

    Science.gov (United States)

    Rohini Kumar, P.; Ramesh, K. V.; Venkateswarlu, P.

    2017-08-01

    Experiments were conducted to investigate the effect of various pertinent dynamic and geometric variables on individual phase holdups in a three-phase fluidized bed in the presence of a string of spheres promoter. Bed porosity was determined from measured bed height. Gas holdup was calculated from pressure drop data. Liquid hold was obtained by subtracting the sum of gas and solids holdup from unity. An electrolyte belonging to ferri-ferro redox system has been used as liquid phase. Glass balls of different sizes were chosen as fluidizing solids and nitrogen was employed as gas phase. The data on gas holdup, liquid holdup and bed porosity were graphically analyzed and correlation equations were obtained.

  11. Fluidized-bed atomic layer deposition reactor for the synthesis of core-shell nanoparticles.

    Science.gov (United States)

    Didden, Arjen P; Middelkoop, Joost; Besling, Wim F A; Nanu, Diana E; van de Krol, Roel

    2014-01-01

    The design of a fluidized bed atomic layer deposition (ALD) reactor is described in detail. The reactor consists of three parts that have all been placed in one protective cabinet: precursor dosing, reactor, and residual gas treatment section. In the precursor dosing section, the chemicals needed for the ALD reaction are injected into the carrier gas using different methods for different precursors. The reactor section is designed in such a way that a homogeneous fluidized bed can be obtained with a constant, actively controlled, reactor pressure. Furthermore, no filters are required inside the reactor chamber, minimizing the risk of pressure increase due to fouling. The residual gas treatment section consists of a decomposition furnace to remove residual precursor and a particle filter and is installed to protect the pump. In order to demonstrate the performance of the reactor, SiO2 particles have been coated with TiO2 using tetrakis-dimethylamino titanium (TDMAT) and H2O as precursors. Experiments with varying pulse times show that saturated growth can be obtained with TDMAT pulse times larger than 600 s. Analysis of the powder with High-Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) and energy dispersive X-ray spectroscopy confirmed that after 50 cycles, all SiO2 particles were coated with a 1.6 nm homogenous shell of TiO2.

  12. Multi-stage-flash desalination plants of relative small performance with integrated pressurized water reactors as a nuclear heat source

    International Nuclear Information System (INIS)

    Petersen, G.; Peltzer, M.

    1977-01-01

    In the Krupp-GKSS joint study MINIPLEX the requirements for seawater-desalination plants with a performance in the range of 10 000 to 80 000 m 3 distillate per day heated by a nuclear reactor are investigated. The reactor concept is similar to the Integrated Pressurized Water Reactor (IPWR) of the nuclear ship OTTO HAHN. The design study shows that IPWR systems have specific advantages up to 200 MWth compared to other reactor types at least being adapted for single- and dual-purpose desalination plants. The calculated costs of the desalinated water show that due to fuel cost advantages of reactors small and medium nuclear desalination plants are economically competetive with oil-fired plants since the steep rise of oil price in autumn 1973. (author)

  13. Changes in pulmonary artery systolic pressure and right ventricular function in patients with end-stage renal disease on maintenance dialysis.

    Science.gov (United States)

    Santosh, Sadashiv; Chu, Cheng; Mwangi, John; Narayan, Melin; Mosman, Amy; Nayak, Ravi; Philipneri, Marie

    2017-10-20

    Pulmonary hypertension is common in patients with end-stage renal disease, and portends a poor prognosis. There are little data in this population, and previous studies have not evaluated quantitative changes in hemodynamics over time while on maintenance dialysis. This study sought to estimate changes in pulmonary artery systolic pressure (PASP) and right ventricular function over time, and to predict PASP change using clinical variables routinely available at time of initial measurement, in patients on maintenance dialysis. We retrospectively studied patients with end-stage renal disease at a university-affiliated dialysis center who had two separate echocardiograms 1-4 years apart. Seventy-six patients (65 hemodialysis, 11 peritoneal dialysis) were included. PASP was estimated by echocardiography. Baseline PASP was predicted by left-sided valvular disease, anemia, COPD, left-ventricular mass index, and hemodialysis modality (p=0.07 for modality). Average increase in PASP was 2.41 mmHg per year. Higher rates of PASP change were predicted by E/e' ratio by tissue doppler on echocardiogram, diabetes mellitus, low LV mass, and left-sided valvular heart disease (p=0.07 for valvular disease). Patients with higher PASP had higher incidence of new-onset right ventricular dysfunction. In patients with end-stage renal disease, PASP increases over time. Changes are moderately predictable. Higher PASP predicted development of right ventricular dysfunction. This article is protected by copyright. All rights reserved.

  14. Three-Dimensional Unsteady Simulation of a Modern High Pressure Turbine Stage Using Phase Lag Periodicity: Analysis of Flow and Heat Transfer

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali; Luk, Daniel F.; Chen, Jen-Ping

    2010-01-01

    Unsteady three-dimensional RANS simulations have been performed on a highly loaded transonic turbine stage and results are compared to steady calculations as well as experiment. A low Reynolds number k- turbulence model is employed to provide closure for the RANS system. A phase-lag boundary condition is used in the periodic direction. This allows the unsteady simulation to be performed by using only one blade from each of the two rows. The objective of this paper is to study the effect of unsteadiness on rotor heat transfer and to glean any insight into unsteady flow physics. The role of the stator wake passing on the pressure distribution at the leading edge is also studied. The simulated heat transfer and pressure results agreed favorably with experiment. The time-averaged heat transfer predicted by the unsteady simulation is higher than the heat transfer predicted by the steady simulation everywhere except at the leading edge. The shock structure formed due to stator-rotor interaction was analyzed. Heat transfer and pressure at the hub and casing were also studied. Thermal segregation was observed that leads to the heat transfer patterns predicted by steady and unsteady simulations to be different.

  15. Gas back-mixing studies in membrane assisted bubbling fluidized beds

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; van Sint Annaland, M.; Kuipers, J.A.M.

    2007-01-01

    Fluidized beds employing fine powders are finding increased application in the chemical and petrochemical industry because of their excellent mass and heat transfer characteristics. However, in fluidized bed chemical reactors axial gas back mixing can strongly decrease the conversion and

  16. 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

  17. Principles of a novel multistage circulating fluidized bed reactor for biomass gasification

    NARCIS (Netherlands)

    Kersten, Sascha R.A.; Prins, W.; van der Drift, Bram; van Swaaij, Willibrordus Petrus Maria

    2003-01-01

    In this paper a novel multistage circulating fluidized bed reactor has been introduced. The riser of this multistage circulating fluidized bed consists of several segments (seven in the base-case design) in series each built-up out of two opposite cones. Due to the specific shape, a fluidized bed

  18. An experimental study of the effect of collision properties on spout fluidized bed dynamics

    NARCIS (Netherlands)

    van Buijtenen, M.S.; Börner, Matthias; Deen, N.G.; Heinrich, Stefan; Antonyuk, Sergiy; Kuipers, J.A.M.

    2009-01-01

    In this paper we experimentally study the effect of collision properties of different particle systems on the bed dynamics of a spout fluidized bed. This is done in different flow regimes: the spout-fluidization regime (case A), the jet-in-fluidized-bed regime (case B) and the spouting-with-aeration

  19. Artificial neural network models for biomass gasification in fluidized bed gasifiers

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Hernández, J. Alfredo; Bruno, Joan Carles

    2013-01-01

    Artificial neural networks (ANNs) have been applied for modeling biomass gasification process in fluidized bed reactors. Two architectures of ANNs models are presented; one for circulating fluidized bed gasifiers (CFB) and the other for bubbling fluidized bed gasifiers (BFB). Both models determin...

  20. Application of sedimentation model to uniform and segregated fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Shippy, J.L. III; Watson, J.S.

    1990-10-24

    This paper incorporates concepts of unimodal and bimodal sedimentation to develop a model that accurately predicts bed expansion during particulate fluidization. During bed expansion a particle is considered to be fluidized not by the pure fluid, but by a slurry consisting of the pure fluid and other surrounding particles. The contributions of the other surrounding particles to the additional buoyant and drag forces are accounted for with the use of effective fluid or slurry properties, density and viscosity. As bed expansion proceeds, influences of the surrounding particles decrease; therefore, these effective properties are functions of the changing void fraction of the suspension. Furthermore, the expansion index, which empirically represents the degree to which viscous and inertial forces are present, is traditionally a function of a constant terminal Reynold's number. Because the effective fluid properties are considered to be changing as fluidization proceeds, the degree to which viscous and inertial forces also changes; therefore, the expansion index is written as a function of a local or intermediate Reynold's number. These concepts are further extended to bimodal fluidization in which small or light particles aid in the fluidization of the large or heavy particles. The results indicate that the proposed model more accurately predicts particulate bed expansion for a wider range of systems (gas -- liquid, low Reynold's number -- high Reynold's number) than other analytical or empirical models.

  1. Process analysis of fluidized bed granulation.

    Science.gov (United States)

    Rantanen, J; Jørgensen, A; Räsänen, E; Luukkonen, P; Airaksinen, S; Raiman, J; Hänninen, K; Antikainen, O; Yliruusi, J

    2001-10-17

    This study assesses the fluidized bed granulation process for the optimization of a model formulation using in-line near-infrared (NIR) spectroscopy for moisture determination. The granulation process was analyzed using an automated granulator and optimization of the verapamil hydrochloride formulation was performed using a mixture design. The NIR setup with a fixed wavelength detector was applied for moisture measurement. Information from other process measurements, temperature difference between process inlet air and granules (T(diff)), and water content of process air (AH), was also analyzed. The application of in-line NIR provided information related to the amount of water throughout the whole granulation process. This information combined with trend charts of T(diff) and AH enabled the analysis of the different process phases. By this means, we can obtain in-line documentation from all the steps of the processing. The choice of the excipient affected the nature of the solid-water interactions; this resulted in varying process times. NIR moisture measurement combined with temperature and humidity measurements provides a tool for the control of water during fluid bed granulation.

  2. Fluidized bed combustion and gasification of corncobs

    Energy Technology Data Exchange (ETDEWEB)

    Butuk, N.; Morey, R.V.

    1987-01-01

    A 15.2 cm (6 in) diameter fluidized bed reactor was evaluated in combustion and gasification modes using hammer milled corncobs with average particle size of 0.2 cm (0.08 in). Combustion tests were run at 10 and 32% w.b. moisture contents and 710 degrees C and 815 degrees C bed temperatures. Heat output rates of 13.4 to 16.2 MJ/h were achieved. Gasification tests were run at 10 and 22% w.b. moisture contents and 710 degrees C bed temperature, and heat output rates of 84 to 133 MJ/h were achieved. Particulates in the exhaust gases were determined in both the combustion and gasification modes of operation. The measurements showed the inadequacy of the flame holder for flaring the gas in the gasification mode. A combustion model based on elemental balances and the first law of thermodynamics was developed and compared to experimental results. The model adequately predicted fuel-air ratios and exhaust gas mass fractions in the combustion mode.

  3. Radioisotope applications on fluidized catalytic cracking units

    International Nuclear Information System (INIS)

    Charlton, J.S.

    1997-01-01

    Radioisotopes are used to trace the flow of all the phases of Fluidized Catalytic Cracking process in oil refineries. The gaseous phases, steam, hydrocarbon vapour and air, are generally traced using a noble-gas isotope, 41 Ar, 79 Kr or 85 Kr. An appropriate tracer for the catalyst is produced by irradiating a catalyst sample in a nuclear reactor. The activation products, 140 La and 24 Na provide appropriate radioactive 'labels' for the catalyst, which is reinjected into the FCC. An advantage of this approach is that it facilitates the study of the behaviour of different particle size fractions. Radioisotopes as sealed sources of gamma radiation are used to measure catalyst density variations and density distributions in critical parts of the unit. An important trend in radioisotope applications is the increasing use of the information they produce as inputs to or as validation of, mathematical process models. In line with the increasing sophistication of the models, the technology is undergoing continuous refinement. Developments include the investigation of more efficient, more convenient tracers, the introduction of systems to facilitate more rapid and comprehensive data acquisition and software refinements for enhanced data analysis

  4. Mathematical Modelling of Drying Kinetics of Wheat in Electron Fired Fluidized Bed Drying System

    Science.gov (United States)

    Deomore, Dayanand N.; Yarasu, Ravindra B.

    2018-02-01

    The conventional method of electrical heating is replaced by electron firing system. The drying kinetics of wheat is studied using electron fired fluidized bed dryer. The results are simulated by using ANSYS. It was observed that the graphs are in agreement with each other. Therefore, the new proposed electronic firing system can be employed instead of electrical firing. It was observed that the drop in Relative Humidity in case of Electrical heating is 68.75% for temp reaching up to 70° C in 67 sec for pressure drop of 13 psi while for the electronic Firing system it is 67.6 % temp reaches to 70° C in 70 sec for pressure drop of 12.67 psi. As the results are in agreement with each other it was concluded that for the grains like wheat which has low initial moisture content both systems can be used.

  5. In situ detection of two-stage crystallization in ZrTiCuNiBe under high pressure and high temperature

    CERN Document Server

    Sun, L L; Wu, Q; Zhan, Z J; Cao, L M; Wang, L M; Shao, G J; Zhang, J; Wang, W K

    2002-01-01

    Structural changes in bulk metallic Zr sub 4 sub 1 sub . sub 2 Ti sub 1 sub 3 sub . sub 8 Cu sub 1 sub 2 sub . sub 5 Ni sub 1 sub 0 Be sub 2 sub 2 sub . sub 5 glass subjected to heat treatments under high pressure were investigated by means of synchrotron radiation x-ray diffraction (SRXRD). In situ SRXRD measurements showed that the crystallization process of this material is comprised of two stages. Subsequent heating at 10 GPa converts the sample from the amorphous (Am) phase into a metastable fcc phase and then leads to the fcc phase changing back to the Am phase, indicating that there is a kind of 'reversible' phase transition phenomenon occurring in the alloy. Such phenomenon is explained on the basis of free energy considerations.

  6. Iyengar Yoga versus Enhanced Usual Care on Blood Pressure in Patients with Prehypertension to Stage I Hypertension: a Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Debbie L. Cohen

    2011-01-01

    Full Text Available The prevalence of prehypertension and Stage 1 hypertension continues to increase despite being amenable to non-pharmacologic interventions. Iyengar yoga (IY has been purported to reduce blood pressure (BP though evidence from randomized trials is lacking. We conducted a randomized controlled trial to assess the effects of 12 weeks of IY versus enhanced usual care (EUC (based on individual dietary adjustment on 24-h ambulatory BP in yoga-naïve adults with untreated prehypertension or Stage 1 hypertension. In total, 26 and 31 subjects in the IY and EUC arms, respectively, completed the study. There were no differences in BP between the groups at 6 and 12 weeks. In the EUC group, 24-h systolic BP (SBP, diastolic BP (DBP and mean arterial pressure (MAP significantly decreased by 5, 3 and 3 mmHg, respectively, from baseline at 6 weeks (P < .05, but were no longer significant at 12 weeks. In the IY group, 24 h SBP was reduced by 6 mmHg at 12 weeks compared to baseline (P = .05. 24 h DBP (P < .01 and MAP (P < .05 decreased significantly each by 5 mmHg. No differences were observed in catecholamine or cortisol metabolism to explain the decrease in BP in the IY group at 12 weeks. Twelve weeks of IY produces clinically meaningful improvements in 24 h SBP and DBP. Larger studies are needed to establish the long term efficacy, acceptability, utility and potential mechanisms of IY to control BP.

  7. Understanding and predicting bed humidity in fluidized bed granulation.

    Science.gov (United States)

    Hu, Xinhui; Cunningham, John; Winstead, Denita

    2008-04-01

    Bed humidity is a critical parameter that needs to be controlled in a fluidized bed granulation to ensure reliability. To predict and control the bed humidity during the fluidized bed granulation process, a simple model based on the mass conservation of moisture was developed. The moisture mass balance model quantitatively simulates the effects of spray rate, binder solution concentration, airflow rate, inlet air temperature, and dew point on the bed humidity. The model was validated by a series of granulations performed in different scale granulators including Glatt GPCG-1, GPCG-15, and GPCG-60. Good agreement was observed between the theoretical prediction and the measured loss on drying (LOD). The model developed in the current work enables us to choose the appropriate parameters for the fluidized bed granulation and can be used as a valuable tool in process scaling-up. 2007 Wiley-Liss, Inc

  8. Experimental study of fluidized bed agglomeration of acerola powder

    Directory of Open Access Journals (Sweden)

    G. C. Dacanal

    2008-03-01

    Full Text Available The aim of this work was to study the main effects of acerola powder on fluidized bed agglomeration. A 2(4-1 fractional factoring design was used to evaluate the main operating conditions (fluidizing air temperature, fluidizing air velocity, atomizing air flow and height of nozzle in the bed. The mechanical and physicochemical product changes were determined by analysis of particle diameter, moisture content, wetting time and bed porosity. The particle enlargement by agglomeration occurred when the relative humidity in the bed increased and, thus, the moisture of the product increased. However, the excessive increase in relative humidity resulted in a decrease in yield, caused by caking and product incrustation. The consolidation of small granules resulted in an increase in the instant properties, decreasing the wetting time and increasing the solubility in a short period of agitation.

  9. Thermal denitrification of evaporators concentrates in reactor with fluidized bed

    International Nuclear Information System (INIS)

    Brugnot, C.

    1993-11-01

    As part of the treatments of liquid wastes coming from the Marcoule reprocessing plant, the study of a thermal denitrification process for evaporator concentrates has been chosen by the CEA/CEN Cadarache: the fluidized-bed calcination. This work presents the study of a calcination pilot-plant for wastes with a very high sodium nitrate content. After a reactional analysis carried out in a thermobalance on samples which are representative of the fluidized-bed compounds, the perfecting of many of the plant parameters - such as the solution injection system - was carried out on a scale-model at first. Then, it was verified on the pilot-plant, and some experiments have been carried out. A mathematical model for the particle growth inside the fluidized-bed is proposed. (author). 179 refs., 65 figs., 23 tabs

  10. Simultaneous nitrogen and organics removal using membrane aeration and effluent ultrafiltration in an anaerobic fluidized membrane bioreactor

    KAUST Repository

    Ye, Yaoli

    2017-08-03

    Dissolved methane and a lack of nutrient removal are two concerns for treatment of wastewater using anaerobic fluidized bed membrane bioreactors (AFMBRs). Membrane aerators were integrated into an AFMBR to form an Aeration membrane fluidized bed membrane bioreactor (AeMFMBR) capable of simultaneous removal of organic matter and ammonia without production of dissolved methane. Good effluent quality was obtained with no detectable suspended solids, 93±5% of chemical oxygen demand (COD) removal to 14±11 mg/L, and 74±8% of total ammonia (TA) removal to 12±3 mg-N/L for domestic wastewater (COD of 193±23 mg/L and TA of 49±5 mg-N/L) treatment. Nitrate and nitrite concentrations were always low (< 1 mg-N/L) during continuous flow treatment. Membrane fouling was well controlled by fluidization of the granular activated carbon (GAC) particles (transmembrane pressures maintained <3 kPa). Analysis of the microbial communities suggested that nitrogen removal was due to nitrification and denitrification based on the presence of microorganisms associated with these processes.

  11. Study on biomass circulation and gasification performance in a clapboard-type internal circulating fluidized bed gasifier.

    Science.gov (United States)

    Zhou, Zhao-qiu; Ma, Long-long; Yin, Xiu-li; Wu, Chuang-zhi; Huang, Li-cheng; Wang, Chu

    2009-01-01

    We investigated the solid particle flow characteristics and biomass gasification in a clapboard-type internal circulating fluidized bed reactor. The effect of fluidization velocity on particle circulation rate and pressure distribution in the bed showed that fluidization velocities in the high and low velocity zones were the main operational parameters controlling particle circulation. The maximum internal circulation rates in the low velocity zone came almost within the range of velocities in the high velocity zone, when u(H)/u(mf)=2.2-2.4 for rice husk and u(H)/u(mf)=3.5-4.5 for quartz sand. In the gasification experiment, the air equivalence ratio (ER) was the main controlling parameter. Rice husk gasification gas had a maximum heating value of around 5000 kJ/m(3) when ER=0.22-0.26, and sawdust gasification gas reached around 6000-6500 kJ/m(3) when ER=0.175-0.24. The gasification efficiency of rice husk reached a maximum of 77% at ER=0.28, while the gasification efficiency of sawdust reached a maximum of 81% at ER=0.25.

  12. In Developping a Bench-Scale Circulating Fluidized Bed Combustor to Burn High Ash Brazilian Coal-Dolomites Mixtures

    Science.gov (United States)

    Ramírez Behainne, Jhon Jairo; Hory, Rogério Ishikawa; Goldstein, Leonardo; Bernárdez Pécora, Araí Augusta

    This work considers some of the questions in burning high ash Brazilian coal-dolomite mixtures in a bench-scale circulating fluidized bed combustor (CFBC). Experimental tests were performed with the CE4500 coal from Santa Catarina State, in southern Brazil, with a Sauter mean diameter d p =43 μm. The coal particles were mixed with dolomite particles of d p = 111 μm and this fuel mixture was fed into the circulating fluidized reactor, previously loaded with quartz sand particles of d p =353 μm. This inert material was previously heated by the combustion of liquefied petroleum gas up to the ignition temperature of the fuel mixture. The CFBC unit has a 100mm internal diameter riser, 4.0m high, as well as a 62.8mm internal diameter downcomer. The loop has a cyclone, a sampling valve to collect particles and a 62.8mm internal diameter L-valve to recirculate the particles in the loop. A screw feeder with a rotation control system was used to feed the fuel mixture to the reactor. The operational conditions were monitored by pressure taps and thermocouples installed along the loop. A data acquisition system showed the main operational conditions to control. Experimental tests performed put in evidence the problems found during bed operation, with special attention to the solids feed device, to the L-valve operation, to particle size, solids inventory, fluidized gas velocity, fuel mixture and recirculated solids feeding positions.

  13. Employment of fluidized bed ash as a basecourse material; Ryudosho nenshobai wo genryo to shita robanzai no jitsuyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, I. [Center for Coal Utilization, Japan, Tokyo (Japan); Tsuzura, K. [Naruto Salt Mfg. Co. Ltd., Tokushima (Japan); Izumi, H. [Nippon Hodo Co. Ltd., Tokyo (Japan); Goto, H. [Electric Power Development Co. Ltd., Tokyo (Japan); Nagaoka, S. [Kawasaki Heavy Industries, Ltd., Kobe (Japan)

    1996-09-01

    Generation of coal ash from coal burning fluidized beds reaches 400,000 tons annually, which is anticipated to increase still more in the future. This paper relates to works to develop a basecourse material manufacturing technology by utilizing excellent hydration and solidification characteristics of fluidized bed ash. The developmental works have been moved forward as a subsidy operation of the Agency of Natural Resources and Energy. Upon having obtained a prospect of practical application of the development, the research results are reported in this paper. Coal ash produced in a fluidized bed boiler goes through the following processes: it is added with water and kneaded; formed into rectangular parallelepiped having sides of 10 to 30 cm long by using a forming machine of vibrating and pressurizing type; cured in steam at 60 degC; crushed into sizes smaller than 40 mm; and made into a basecourse material upon adjusting the grain size. A pilot plant completed in 1993 has produced 15,000 tons of the material to date. Properties required as a basecourse material, such as hazardous metal dissolving characteristics and strength sufficiently meet relevant standards or the targeted value. Demonstration tests of the material on roads including public roads have shown as good result as those obtained from standard basecourse materials. 8 refs., 8 figs., 7 tabs.

  14. Biomass gasification using nickel loaded brown coal char in fluidized bed gasifier at relatively low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Le, D.D.; Xiao, X.B.; Morishita, K.; Takarada, T. [Gunma University, Gumma (Japan)

    2009-07-01

    Our work focuses on developing nickel loaded brown coal char as a new catalyst to decompose tar and to enhance quality of product gas delivered from woody biomass pyrolysis at relatively low temperatures of 823 K and 923 K. It is carried out in two-stage fixed-bed reactor and a lab scale fluidized bed gasifier (FBG) under various conditions. Inside of gasifier is constructed by two beds, the primary one is a fluidized bed with sand. and the second one is a catalyst bed. The catalyst bed is used to evaluate and to compare catalytic activity between the new catalyst and a conventional Ni/Al{sub 2}O{sub 3} catalyst. The new catalyst is prepared by ion exchange method, dried at 380 K in nitrogen for 24 h, and is then calcined at 923 K in nitrogen for 90 min. The temperature as a function of gas yield and the effect of catalysts on gas yield in presence and absence of steam are investigated in this study. The new catalyst has shown high catalytic activity and stable activity and given the high quality of product gas in presence of steam.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rokkam, Ram [Iowa State Univ., Ames, IA (United States)

    2012-01-01

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

  16. Iron crystallization in a fluidized-bed Fenton process.

    Science.gov (United States)

    Boonrattanakij, Nonglak; Lu, Ming-Chun; Anotai, Jin

    2011-05-01

    The mechanisms of iron precipitation and crystallization in a fluidized-bed reactor were investigated. Within the typical Fenton's reagent dosage and pH range, ferric ions as a product from ferrous ion oxidation would be supersaturated and would subsequently precipitate out in the form of ferric hydroxide after the initiation of the Fenton reaction. These precipitates would simultaneously crystallize onto solid particles in a fluidized-bed Fenton reactor if the precipitation proceeded toward heterogeneous nucleation. The heterogeneous crystallization rate was controlled by the fluidized material type and the aging/ripening period of the crystallites. Iron crystallization onto the construction sand was faster than onto SiO(2), although the iron removal efficiencies at 180 min, which was principally controlled by iron hydroxide solubility, were comparable. To achieve a high iron removal rate, fluidized materials have to be present at the beginning of the Fenton reaction. Organic intermediates that can form ferro-complexes, particularly volatile fatty acids, can significantly increase ferric ion solubility, hence reducing the crystallization performance. Therefore, the fluidized-bed Fenton process will achieve exceptional performance with respect to both organic pollutant removal and iron removal if it is operated with the goal of complete mineralization. Crystallized iron on the fluidized media could slightly retard the successive crystallization rate; thus, it is necessary to continuously replace a portion of the iron-coated bed with fresh media to maintain iron removal performance. The iron-coated construction sand also had a catalytic property, though was less than those of commercial goethite. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. The preparation of the sustained release metformin hydrochloride microcapsules by the Wurster fluidized bed.

    Science.gov (United States)

    Cao, Jin; Liu, Hongfei; Pan, Weisan; Sun, Changshan; Feng, Yingshu; Zhong, Hui; Shi, Shuang Shuang; He, Yan

    2014-07-01

    The main objective of this study was to prepare sustained release metformin hydrochloride microcapsules by the Wurster fluidized bed and to obtain the optimized coating process and formulation. Fine microcapsules without agglomeration were obtained in a continuous coating process with the atomization air pressure of 0.2Mpa and an appropriate coating speed temperature. With other design variables of coating process fixed, the effects of different fluidizing air volume, coating temperature, coating speed, coating material, coating materials amount, plasticizer type and plasticizer amount on drug release were investigated respectively. Coating solution was achieved by dissolving EC45cps of 21 g, EC100cps of 7 g, DBS of 2.8 g and talcum powder of 8 g in ethanol to get a final volume of 500 ml. Particles of 150g along with 500mL coating solution would be fine. The results showed that with the air volume of 35 m3•h-1, coating temperature of 35o, coating speed of 6 mL•min-1 and proper amount of coating solution, fine microcapsules were obtained. The mean diameter of the microcapsules obtained eventually were 213 μm and the drug content were 23%, which was suitable for producing a suspension. Particle diameter distribution corresponded to the normal distribution and obviously prolonged drug-release was achieved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bischi, Aldo

    2012-05-15

    particles concentration in the upper section of the reactors, thus the gas solids contact. They are interconnected by means of two pneumatically controlled divided loop-seals and a bottom extraction/lift. The system is designed to be as compact as possible, to help up-scaling and enclosure into a pressurized vessel, aiming pressurization in a second phase. In addition several industrial solutions have been utilized, from highly loaded cyclones to several levels of secondary air injections.The divided loop-seals are capable to internally re-circulate part of the entrained solids, uncoupling the solids entrainment from the solids exchange. This will provide a better control on the process increasing its flexibility and helping to fulfil downstream requirements. No mechanical valves are utilized, but gas injections. The bottom extraction compensates the lower entrainment of the FR which has less fluidising gas availability and smaller cross section than the AR. The lift allows adjusting the reactors bottom inventories, thus the pressures in the bottom sections of the reactors. In this way the divided loop-seals are not exposed to large pressure unbalances and the whole system is hydrodynamically more robust. The proposed design was finally validated by means of a full scale cold flow model (CFM), without chemical reactions. A thorough evaluation of the scaling state-of-the-art in fluidization engineering has been done; two are the approaches. One consists of building a small scale model which resembles the hydrodynamics of the bigger hot setup, by keeping constant a set of dimensionless numbers. The other is based on the construction of a full scale model, being careful to be in the same fluidization regime and to utilize particles with the same fluidization properties as the hot setup. In this way the surface to volume ratio is kept the same as that one of the hot rig. The idea presented in this work combines those two strategies, building a full scale CFM. In this way, it

  19. Estimating average shock pressures recorded by impactite samples based on universal stage investigations of planar deformation features in quartz - Sources of error and recommendations

    Science.gov (United States)

    Holm-Alwmark, S.; Ferrière, L.; Alwmark, C.; Poelchau, M. H.

    2018-01-01

    Planar deformation features (PDFs) in quartz are the most widely used indicator of shock metamorphism in terrestrial rocks. They can also be used for estimating average shock pressures that quartz-bearing rocks have been subjected to. Here we report on a number of observations and problems that we have encountered when performing universal stage measurements and crystallographically indexing of PDF orientations in quartz. These include a comparison between manual and automated methods of indexing PDFs, an evaluation of the new stereographic projection template, and observations regarding the PDF statistics related to the c-axis position and rhombohedral plane symmetry. We further discuss the implications that our findings have for shock barometry studies. Our study shows that the currently used stereographic projection template for indexing PDFs in quartz might induce an overestimation of rhombohedral planes with low Miller-Bravais indices. We suggest, based on a comparison of different shock barometry methods, that a unified method of assigning shock pressures to samples based on PDFs in quartz is necessary to allow comparison of data sets. This method needs to take into account not only the average number of PDF sets/grain but also the number of high Miller-Bravais index planes, both of which are important factors according to our study. Finally, we present a suggestion for such a method (which is valid for nonporous quartz-bearing rock types), which consists of assigning quartz grains into types (A-E) based on the PDF orientation pattern, and then calculation of a mean shock pressure for each sample.

  20. Volatiles combustion in fluidized beds. Technical progress report, 4 March 1993--3 June 1993

    Energy Technology Data Exchange (ETDEWEB)

    Hesketh, R.P.

    1993-09-01

    The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization will be performed to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. The work conducted during the period 4 March, 1993 through 3 June, 1993 is reported in this technical progress report. The work during this time period consists primarily of the startup and trouble shooting of the fluidized bed reactor and gas phase modeling of methane and propane.

  1. Refractory experience in circulating fluidized bed combustors, Task 7

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, R.Q.

    1989-11-01

    This report describes the results of an investigation into the status of the design and selection of refractory materials for coal-fueled circulating fluidized-bed combustors. The survey concentrated on operating units in the United States manufactured by six different boiler vendors: Babcock and Wilcox, Combustion Engineering, Foster Wheeler, Keeler Dorr-Oliver, Pyropower, and Riley Stoker. Information was obtained from the boiler vendors, refractory suppliers and installers, and the owners/operators of over forty units. This work is in support of DOE's Clean Coal Technology program, which includes circulating fluidized-bed technology as one of the selected concepts being evaluated.

  2. Atmospheric fluidized bed coal combustion research, development and application

    CERN Document Server

    Valk, M

    1994-01-01

    The use of fluidized bed coal combustion technology has been developed in the past decade in The Netherlands with a view to expanding the industrial use of coal as an energy supply. Various research groups from universities, institutes for applied science and from boiler industries participated and contributed to this research area. Comprehensive results of such recent experimentation and development work on atmospheric fluidized bed combustion of coal are covered in this volume. Each chapter, written by an expert, treats one specific subject and gives both the theoretical background as well a

  3. Transformations of calcium sulphates in solidified carbonated volatile fluidized ashes

    Directory of Open Access Journals (Sweden)

    Marian Jacek Łączny

    2017-01-01

    During the investigation it was assumed that calcium carbonate, being poorly water-soluble, would not react with the remaining components of the porous water of the volatile fluidized ash. Crystalline phases of calcium sulphates, anhydrite, gypsum and bassanite occurring in bound volatile fluidized ashes after carbonation demonstrate the possibility of crystallization in the presence of calcium carbonate. In particular, a change in the concentration of bassanite indicates that this phase, as a precursor to the crystallization of gypsum, may play a significant role in the process of binding carbonated volatile ashes.

  4. Boundary conditions for soft glassy flows: slippage and surface fluidization.

    Science.gov (United States)

    Mansard, Vincent; Bocquet, Lydéric; Colin, Annie

    2014-09-28

    We explore the question of surface boundary conditions for the flow of a dense emulsion. We make use of microlithographic tools to create surfaces with well controlled roughness patterns and measure using dynamic confocal microscopy both the slip velocity and the shear rate close to the wall, which we relate to the notion of surface fluidization. Both slippage and wall fluidization depend non-monotonously on the roughness. We interpret this behavior within a simple model in terms of the building of a stratified layer and the activation of plastic events by the surface roughness.

  5. Internal dust recirculation system for a fluidized bed heat exchanger

    Science.gov (United States)

    Gamble, Robert L.; Garcia-Mallol, Juan A.

    1981-01-01

    A fluidized bed heat exchanger in which air is passed through a bed of particulate material containing fuel disposed in a housing. A steam/water natural circulation system is provided in a heat exchange relation to the bed and includes a steam drum disposed adjacent the bed and a tube bank extending between the steam drum and a water drum. The tube bank is located in the path of the effluent gases exiting from the bed and a baffle system is provided to separate the solid particulate matter from the effluent gases. The particulate matter is collected and injected back into the fluidized bed.

  6. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C

    2006-12-22

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

  7. Numerical simulations and correlations on the coal -conveying gas flow in pipe for fluidized -bed coal gasification facility

    International Nuclear Information System (INIS)

    Lee, Chan; Lee, Jin Wook; Kwon, Tae Wan; Kim, Gyoo Tae

    2014-01-01

    CFD modeling and simulation are made on the key flow elements, vertical, horizontal pipes and elbow pipes , used in the pneumatic coal -transport system of fluidized -bed gasification test facility. The coal- gas flow inside the flow elements are modeled by combining Reynolds -stress Averaged Navier- Stokes equations Solver (RANS), k- ε turbulence model and Discrete Phase Model (DPM) in the ANSYS Fluent code. Using the developed coal -gas flow analysis model, computations are carried out to investigate the gas flow path, the coal particle behavior and the pressure loss characteristics in flow element at various coal/ gas loading ratio and coal mass flux. The present prediction results show the coal -gas flow behavior of each flow element is changed from dilute -flow to dense -flow pattern at a specific coal/gas loading ratio where pressure loss is abruptly increased. From the numerical results, the present study also provides the limiting coal/gas loading conditions to secure stable coal feeding and the correlations for pressure losses in horizontal, vertical and elbow pipes, which can be suitable for the design guidelines of actual fluidized -bed coal gasification. Key words : Pneumatic Coal -Transport; Coal -Gas Flow, Dense Phase Flow; Dilute Phase Flow; Pressure Loss; Coal/Gas Loading Ratio; Correlation

  8. Melt granulation in fluidized bed: a comparative study of spray-on versus in situ procedure.

    Science.gov (United States)

    Mašić, Ivana; Ilić, Ilija; Dreu, Rok; Ibrić, Svetlana; Parojčić, Jelena; Srčič, Stanko

    2014-01-01

    The aim of this study was to investigate the influence of process parameters, binder content and binder addition method on characteristics of the granules obtained by melt granulation (MG) in fluidized bed. Spray-on experiments were performed according to 2(3) full factorial design. The effect of binder content, molten binder feed rate, and spray air pressure on granule size and size distribution, granule shape, flowability and drug release rate was investigated. In the in situ experiments, the influence of binder particle size and binder content was evaluated. Solid-state characterization was performed by means of differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy. Size of the granules obtained by spray-on procedure was significantly influenced by binder content and spray air pressure, while the width of particle size distribution was mainly affected by binder feed rate. Spray air pressure showed the most significant influence on granule shape. It was shown that smooth and spherical particles with good flow properties may be obtained by both procedures, spray-on and in situ MG. The results obtained indicated the influence of agglomeration mechanism on granule sphericity, with higher degree of granule sphericity observed when immersion and layering was the dominant mechanism. Paracetamol release from granulates was very rapid, but after compression of the granules into tablets, drug release was considerably slower. Solid-state analysis confirmed that the physical form of the granulate components remained unaffected after the MG process. The results presented indicate that MG in fluidized bed could be a good alternative to conventional granulation techniques.

  9. On the entrainment of solid particles from a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Sciazko, M. (Institute of Chemical Processing of Coal, Zabrze (Poland)); Bandrowski, J.; Raczek, J. (Politechnika Slaska, Gliwice (Poland). Inst. of Chemical Engineering and Apparatus Construction)

    1991-04-01

    This paper presents a generalized approach to the phenomenon of entrainment of solids from a fluidized bed. Starting with the discussion of the transport disengaging height (TDH) and of the elutriation of particles above the TDH, one arrives finally at the relationship between the elutriation rate constant, saturation carrying capacity and choking parameters of pneumatic transport. (orig.).

  10. Biofilm detachment mechanisms in a liquid-fluidized bed.

    Science.gov (United States)

    Chang, H T; Rittmann, B E; Amar, D; Heim, R; Ehlinger, O; Lesty, Y

    1991-08-20

    Bed fluidization offers the possibility of gaining the advantages of fixed-film biological processes without the disadvantage of pore clogging. However, the biofilm detachment rate, due to hydrodynamics and particle-to-particle attrition, is very poorly understood for fluidized-bed biofilm processes. In this work, a two-phase fluidized-bed biofilm was operated under a constant surface loading (0.09 mg total organic carbon/cm(2) day) and with a range of bed height (H), fluid velocities (U), and support-particle concentrations (C(p)). Direct measurements were made for the specific biofilm loss rate coefficient (b(s))and the total biofilm accumulation (X(f)L(f)). A hydrodynamic model allowed independent determination of the biofilm density (X(f)), biofilm thickness (L(f)), liquid shear stress (tau), and Reynolds number (Re). Multiple regression analysis of the results showed that increased particle-to-particle attrition, proportional to C(p) and increased turbulence, described by Re, caused the biofilms to be denser and thinner. The specific detachment rate coefficient (b(s)) increased as C(p) and Re increased. Almost all of the 6, values were larger than predicted by a previous model derived for smooth biofilms on a nonfluidized surface. Therefore, the turbulence and attrition of bed fluidization appear to be dominant detachment mechanisms.

  11. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Energy Technology and Environmental Protection

    1997-10-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and the heat transfer of the fluidized bed in the boundary layer near the wall. During the project the concentration and the velocity of the sand particles are measured. The particle concentration and the particle velocity are measured by an image analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The measured particle concentration was at highest slightly over 20 % on the straight wall. As expected, the velocity of the fluidizing gas had the most important role on the particle concentration. The experimental studies of the particle velocity were started last autumn 1996. The velocities of the particles were measured by using a multiple exposure technique. Afterwards the images captured were analyzed by performing a Fourier transform analysis. So far the results have been encouraging and the analyzing work will be ended this spring. (orig.)

  12. substrate reduction kinetics and performance evaluation of fluidized

    African Journals Online (AJOL)

    eobe

    UASB reactor system before the treatment begins [6]. Open pit (aerobic) treatment system which is currently being employed at the brewery is characterized by high sludge generation with its attendant disposal problems. Slaughterhouse wastewater [7] and corn starch wastewater [8] have been treated using Fluidized-bed ...

  13. In silico modeling of in situ fluidized bed melt granulation.

    Science.gov (United States)

    Aleksić, Ivana; Duriš, Jelena; Ilić, Ilija; Ibrić, Svetlana; Parojčić, Jelena; Srčič, Stanko

    2014-05-15

    Fluidized bed melt granulation has recently been recognized as a promising technique with numerous advantages over conventional granulation techniques. The aim of this study was to evaluate the possibility of using response surface methodology and artificial neural networks for optimizing in situ fluidized bed melt granulation and to compare them with regard to modeling ability and predictability. The experiments were organized in line with the Box-Behnken design. The influence of binder content, binder particle size, and granulation time on granule properties was evaluated. In addition to the response surface analysis, a multilayer perceptron neural network was applied for data modeling. It was found that in situ fluidized bed melt granulation can be used for production of spherical granules with good flowability. Binder particle size had the most pronounced influence on granule size and shape, suggesting the importance of this parameter in achieving desired granule properties. It was found that binder content can be a critical factor for the width of granule size distribution and yield when immersion and layering is the dominant agglomeration mechanism. The results obtained indicate that both in silico techniques can be useful tools in defining the design space and optimization of in situ fluidized bed melt granulation. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Population balance modelling of fluidized bed melt granulation: an overview

    NARCIS (Netherlands)

    Tan, H.S.; Goldschmidt, M.J.V.; Boerefijn, R.; Hounslow, M.J.; Salman, A.; Kuipers, J.A.M.

    2005-01-01

    This paper presents an overview of the work undertaken by our group to identify and quantify the rates processes active in fluidized bed melt granulation (FBMG). The process involves the identification and development of physically representative models to mechanistically describe FBMG using both

  15. Study on biomass pyrolysis and gasification in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Su, X.; Wang, Z.; Cheng, C.; Tang, S.; Lu, Z.; Li, D. [Tsinghua University, Beijing (China). Thermal Engineering Department

    2000-08-01

    Experimental investigations of biomass pyrolysis and gasification were performed in a fluidized bed reactor with steam and nitrogen as fluid medium respectively. The size of the stainless steel reactor is 150mm ID and 1360mm in height. Five biomass samples including poplar sawdust, bagasse, cotton stem, eucalyptus globulus and pinus ratiata, have been tested on the facility at the temperatures ranging from 923K to 1073K. During each test run, biomass feedstock was fed into the reactor continuously for twelve minutes and without residue discharge, meanwhile seven gas samples were taken, five during the feeding process and two after the stop of feeding. The transient and accumulated gas yields were measured with a rotameter and a gas meter. The temperatures of the fluidized bed and freeboard were acquired by a system of thermocouples connected with a computer. The gas samples were analyzed on a gas chromatograph. On the basis of the experimental results, the variations of gas yield, gas composition, energy conversion efficiency and mass conversion efficiency with temperature are discussed for each biomass feedstock in both cases of steam and nitrogen fluidization. It has been revealed in this investigation that the presence of steam in the fluidized bed reactor stimulates tar cracking to form the gas species of C{sub 2}H{sub 4}and C{sub 2}H{sub 6}, etc. 8 ref., 15 figs., 6 tabs.

  16. The porosity in a fluidized bed heat transfer model

    NARCIS (Netherlands)

    Visser, G; Visser, G.; Valk, M.

    1993-01-01

    A mathematical model of heat transfer between a fluidized bed and an immersed surface and a model of gas flow and porosity, both recently published, were combined and further modified in the area of low velocities where the particle convective component of heat transfer is low or neglectable.

  17. Technological processes intensification in devices with magneto-fluidized bed

    Directory of Open Access Journals (Sweden)

    Egorov Ivan

    2017-01-01

    Full Text Available The paper shows the efficiency of application of magneto-fluidized bed formed of ferromagnetic materials in press-forms dosed filling and milling devices. For powders without natural fluidity, dosing device is situated between electromagnets creating constant magnetic field with horizontal induction lines and alternating gradient magnetic field with vertical induction lines and higher induction gradient in the lowest part of chamber with powder. This configuration allows development of uniform efflux speed of ferromagnetic powders from 2 mm diameter opening. For example, mass efflux speed of strontium ferrite powder with 1 μm average particle size in magneto-fluidized bed reached 181.1 mg/s and the dosing time of 2000 mg of this powder was 11.1 s. For practical usage of magneto-fluidized bed in the milling device, beater mill is situated between electromagnet poles in the way that induction lines of constant and alternating gradient magnetic fields were mutually perpendicular and parallel to the plane of rotating beaters. Milling of particulate strontium ferrite with 1558.5 μm average particle size during 120 minutes in magneto-fluidized bed allows increasing milling degree in 16.2 times by comparison with processing without electromagnetic effect.

  18. Starch Wastewater Treatment in a Three Phase Fluidized Bed ...

    African Journals Online (AJOL)

    ... out in an inverse fluidized bed bioreactor using low density (870 kg/m3) polypropylene particles. Experiments were carried at different initial substrate concentration of 2250, 4475, 6730 and 8910mg COD/L and for various hydraulic retention time 40, 32, 24, 16 and 8h. Degradation of organic matter was studied at different ...

  19. Low temperature fluidized wood chip drying with monoterpene analysis

    Science.gov (United States)

    Bridget N. Bero; Alarick Reiboldt; Ward Davis; Natalie Bedard; Evan Russell

    2011-01-01

    This paper describes the drying of ponderosa pine wood chips at low (20°C and 50°C) temperatures using a bench-scale batch pulsed fluidizer to evaluate both volatile pine oils (monoterpenes) and moisture losses during drying.

  20. substrate reduction kinetics and performance evaluation of fluidized ...

    African Journals Online (AJOL)

    pilot scale anaerobic fluidized-bed reactor was operated for treating brewery wastewater at nine different hydraulic retention time (HRTs) of 2, 3, 4, 5, 6, 7, 8, 9, and 10hr. The COD reduction efficiencies increased from 9.8% to 74.1% with increasing HRT from 2 to 10hr.Similarly, the corresponding BOD5 reduction efficiencies ...

  1. Dissolved oxygen control in a coupled fluidized bed system

    International Nuclear Information System (INIS)

    Jones, R.M.; Melcer, H.

    1988-01-01

    The biological fluidized bed process is a modification of more conventional fixed film processes, such as the trickling filter, in which wastewater is passed upward through a bed of granular support medium, typically sand, at a sufficient velocity to expand or fluidize the medium. The granular medium provides a large surface area for the establishment of a biological film. The fluidized bed process was selected to investigate the treatment of coking plant wastewaters in view of the significant advantages offered in terms of reduced reactor volumes that result from the high biomass concentration maintained on the support medium. The technical feasibility of treating coal distillation condensates was evaluated during a 3-year study at Environment Canada's Wastewater Technology Centre (WTC). The feed to the pilot scale test system consisted of effluent from fixed and free leg ammonia stills at the by-product coke plant of Dofasco Inc. in Hamilton, Ontario. The pilot plant consisted of two fluidized bed reactors in series, coupled to provide carbon oxidation, nitrification and denitrification in the predenitrification operating mode. The anoxic denitrification reactor was 115 mm in diameter and the oxygenic nitrification reactor, 290 mm in diameter. The bed heights and reactor volumes were adjustable by relocation of the position of the sand/biomass wasting valve. The experimental objective of this research was to determine those operating conditions required to maintain stable nitrification and complete denitrification under both steady state and dynamic operating conditions. Details regarding operating, sampling and analytic procedures have been presented elsewhere. A specific operating problem existed relating to the control of the dissolved oxygen concentration in the oxygenic fluidized bed reactor, the solution of which forms the basis of the paper

  2. Las degradation in a fluidized bed reactor and phylogenetic characterization of the biofilm

    Directory of Open Access Journals (Sweden)

    L. L. Oliveira

    2013-09-01

    Full Text Available A fluidized bed reactor was used to study the degradation of the surfactant linear alkylbenzene sulfonate (LAS. The reactor was inoculated with anaerobic sludge and was fed with a synthetic substrate supplemented with LAS in increasing concentrations (8.2 to 45.8 mg l-1. The removal efficiency of 93% was obtained after 270 days of operation. Subsequently, 16S rRNA gene sequencing and phylogenetic analysis of the sample at the last stage of the reactor operation recovered 105 clones belonging to the domain Bacteria. These clones represented a variety of phyla with significant homology to Bacteroidetes (40%, Proteobacteria (42%, Verrucomicrobia (4%, Acidobacteria (3%, Firmicutes (2%, and Gemmatimonadetes (1%. A small fraction of the clones (8% was not related to any phylum. Such phyla variety indicated the role of microbial consortia in degrading the surfactant LAS.

  3. Activation of PPAR-α in the early stage of heart failure maintained myocardial function and energetics in pressure-overload heart failure.

    Science.gov (United States)

    Kaimoto, Satoshi; Hoshino, Atsushi; Ariyoshi, Makoto; Okawa, Yoshifumi; Tateishi, Shuhei; Ono, Kazunori; Uchihashi, Motoki; Fukai, Kuniyoshi; Iwai-Kanai, Eri; Matoba, Satoaki

    2017-02-01

    Failing heart loses its metabolic flexibility, relying increasingly on glucose as its preferential substrate and decreasing fatty acid oxidation (FAO). Peroxisome proliferator-activated receptor α (PPAR-α) is a key regulator of this substrate shift. However, its role during heart failure is complex and remains unclear. Recent studies reported that heart failure develops in the heart of myosin heavy chain-PPAR-α transgenic mice in a manner similar to that of diabetic cardiomyopathy, whereas cardiac dysfunction is enhanced in PPAR-α knockout mice in response to chronic pressure overload. We created a pressure-overload heart failure model in mice through transverse aortic constriction (TAC) and activated PPAR-α during heart failure using an inducible transgenic model. After 8 wk of TAC, left ventricular (LV) function had decreased with the reduction of PPAR-α expression in wild-type mice. We examined the effect of PPAR-α induction during heart failure using the Tet-Off system. Eight weeks after the TAC operation, LV construction was preserved significantly by PPAR-α induction with an increase in PPAR-α-targeted genes related to fatty acid metabolism. The increase of expression of fibrosis-related genes was significantly attenuated by PPAR-α induction. Metabolic rates measured by isolated heart perfusions showed a reduction in FAO and glucose oxidation in TAC hearts, but the rate of FAO preserved significantly owing to the induction of PPAR-α. Myocardial high-energy phosphates were significantly preserved by PPAR-α induction. These results suggest that PPAR-α activation during pressure-overloaded heart failure improved myocardial function and energetics. Thus activating PPAR-α and modulation of FAO could be a promising therapeutic strategy for heart failure. NEW & NOTEWORTHY The present study demonstrates the role of PPAR-α activation in the early stage of heart failure using an inducible transgenic mouse model. Induction of PPAR-α preserved heart

  4. 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}.

  5. Co-gasification of Colombian coal and biomass in fluidized bed: An experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Jhon F. Velez; Farid Chejne; Carlos F. Valdes; Eder J. Emery; Carlos A. Londono [Universidad Nacional de Colombia, Antioquia (Colombia). Grupo de Termodinamica Aplicada y Energias Alternativas

    2009-03-15

    The main results of an experimental work on co-gasification of Colombian biomass/coal blends in a fluidized bed working at atmospheric pressure are reported in this paper. Several samples of blends were prepared by mixing 6-15wt% biomass (sawdust, rice or coffee husk) with coal. Experimental assays were carried out by using mixtures of different steams/blends (Rvc) and air/blend (Rac) ratios showing the feasibility to implement co-gasification as energetic alternative to produce fuel gas to heat and to generate electricity and the possibility of converting clean and efficiently the refuse coal to a low-heating value gas. 29 refs., 5 figs., 4 tabs.

  6. The effects of agglomeration/defluidization on emission of heavy metals for various fluidized parameters in fluidized-bed incineration

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chiou-Liang; Tsai, Ming-Chih; Chang, Chih-Hung [Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, 811 (China)

    2010-01-15

    The agglomeration/defluidization may be produced to generate the secondary pollutant during incineration. However, the effects of agglomeration/defluidization on heavy metal distribution have rarely been examined. Therefore, the effects of the agglomeration/defluidization process on heavy metal emission in flue gas are studied. The artificial waste is employed to simulate municipal waste and to form agglomerates, which contain alkali metals, earth alkali metals, a mixture of metals (Pb, Cr and Cd) and sawdust. The fluidized parameters (including gas velocity, sand particle size and static bed height) are varied to determine their influences on heavy metal emission. The results indicate that addition of Na increases the risk of agglomeration/defluidization, but the emission concentration of heavy metals decreases during agglomeration/defluidization. The heavy metals may react with Na to form the eutectics or are covered and adhered by the liquid-phase eutectics of Na to stay in sand particle and lead to a decrease in the emission of heavy metals. The system was operated at a low gas velocity that not only easily resulted in agglomeration/defluidization but also increased the emission concentration of heavy metals. Large particles (920 {mu}m), which have a poor fluidized quality, had the highest emission concentration. Small particles (645 {mu}m) were uniformly fluidized to enhance the fluidization quality and to decrease the emission concentration. Additionally, adding Ca did not decrease the heavy metal emission concentration, but maintained the fluidization during eutectic accumulation. The Ca prevented the sand bed from quickly achieving defluidization and prolonged the increased emission of heavy metals after defluidization. (author)

  7. Taking Care of Pressure Sores

    Science.gov (United States)

    ... Tract Infections: Indwelling (Foley) Catheter Taking Care of Pressure Sores [Download this pamphlet: "Taking Care of Pressure ... may not show up right away. Stages of pressure sores and how to care for them: STAGE ...

  8. Design and simulation of a circulating fluidized bed to clean the products of biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Uchoa Neto, Moises; Carvalho, Yuri de Araujo [Dept. de Engenharia Mecanica. Faculdade de Tecnologia. Universidade de Brasilia, DF (Brazil); Oliveira, Taygoara Felamingo de; Barcelos, Manuel [Faculdade do Gama. Universidade de Brasilia, Gama, DF (Brazil)], e-mail: taygoara@unb.br

    2010-07-01

    The main goal of this work is to design a workbench circulating fluidized bed to study the cracking of tar in gases from the processes of biomass gasification. For this, a design methodology based on analytical results and empirical correlations for fluidized beds was employed. In parallel, a numerical code of open source technology (MFIX) for the solution of the transport equations of the multiphase flow in the column of a fluidized bed was used to give support to the choice of the design elements. The whole project of the workbench fluidized bed was completely developed, whose operation parameters such as bed geometry, gas velocity, circulating ratio and void fraction characterize a fast fluidization process. A preliminary mesh convergence study was executed with the numerical tool, that was validated comparing with analytical results. Among the most important results, the code computed the predicted value for the minimum fluidization. (author)

  9. Minimum and Full Fluidization Velocity for Alumina Used in the Aluminum Smelter

    Directory of Open Access Journals (Sweden)

    Paulo Douglas S. de Vasconcelos

    2011-11-01

    Full Text Available Fluidization is an engineering unit operation that occurs when a fluid (liquid or gas ascends through a bed of particles, and these particles get a velocity of minimum fluidization enough to stay in suspension, but without carrying them in the ascending flow. As from this moment the powder behaves as liquid at boiling point, hence the term “fluidization”. This operation is widely used in the aluminum smelter processes, for gas dry scrubbing (mass transfer and in a modern plant for continuous alumina pot feeding (particles’ momentum transfer. The understanding of the alumina fluoride rheology is of vital importance in the design of fluidized beds for gas treatment and fluidized pipelines for pot feeding. This paper shows the results of the experimental and theoretical values of the minimum and full fluidization velocities for the alumina fluoride used to project the state of the art round non‐metallic air‐fluidized conveyor of multiples outlets.

  10. Experimental and Numerical Investigation of Four- Phase Flow (Water–Gasoline-Air-Solid in a Fluidized Bed Column

    Directory of Open Access Journals (Sweden)

    Riyadh S. Al-Turaihi

    2016-03-01

    Full Text Available In this paper four phase fluidized bed is experimentally built and numerically modeled to study the bed characteristics such as ratio (the static bed height of solid particle / the bed diameter (H/D, air, gasoline , and water superficial velocity. The test pipe for the experimental rig is Perspex pipe with 1 m long and 0.0254 m diameter. The 2D numerical model has been established with Ansys fluent 15.0. Pressure drop equation is found to relate the pressure drop with the bed parameters with deviation of 22%. The Four-phases was represented by air, water, gasoline and solid particle. The results show that the pressure of the bed increases as the ratio H/D increases and air, gasoline , and water superficial velocity increases. As well as the expansion of the bed increases as air, gasoline, and water superficial velocity increases.

  11. Two-stage pressure-induced Yb valence change in the hexagonal Laves phase YbAg2: Investigation by time differential perturbed angular γ -γ correlation spectroscopy method and density functional calculations

    Science.gov (United States)

    Tsvyashchenko, A. V.; Nikolaev, A. V.; Salamatin, D. A.; Velichkov, A.; Salamatin, A. V.; Novikov, A. P.; Fomicheva, L. N.; El'kin, F. S.; Bibikov, A. V.; Kozin, M. G.; Budzynski, M.

    2017-12-01

    We have studied the C14 hexagonal Laves phase of YbAg2 at normal conditions and under external pressure up to 19 GPa by the time-differential perturbed angular γ -γ correlation spectroscopy (TDPAC) using 111Cd probe nuclei. Under pressure the valence of Yb undergoes a two-stage transition from 2.8 to 3. The two-stage scenario is characterized by two distinct quadrupole frequencies of 111Cd probes in a silver sublattice, monotonically increasing with pressure and saturating at 8 and 16 GPa. Our experimental data are compared with the density functional studies of the electron band structure of YbAg2, whose results are used for discussion and interpretation of these experiments. We have found that there are two different electric field gradients at inequivalent silver sites and that 4 d states of silver participate in metal bonding, allowing for the formation of the hexagonal Laves phase.

  12. Study of standard tablet formulation based on fluidized-bed granulation.

    Science.gov (United States)

    Sunada, H; Hasegawa, M; Makino, T; Sakamoto, H; Fujita, K; Tanino, T; Kokubo, H; Kawaguchi, T

    1998-03-01

    In this study, acetaminophen, ascorbic acid, and ethenzamide were selected as model drugs for tableting granules. Agitation and fluidized-bed granulation were carried out at three drug contents of 30, 50, and 70%. Compared with agitation granulation, granules made by fluidized-bed granulation showed superior compressibility with wide formulation allowance for drug type and amount. Fluidized-bed granulation resulted in less granule hardness and greater plastic deformability. The granules had considerable compactness and for tablets containing 70% ethenzamide, prolonged disintegration and dissolution times were noted. These are typical features of granules produced by fluidized-bed granulation.

  13. Application and Discussion of Dual Fluidized Bed Reactor in Biomass Energy Utilization

    Science.gov (United States)

    Guan, Haibin; Fan, Xiaoxu; Zhao, Baofeng; Yang, Liguo; Sun, Rongfeng

    2018-01-01

    As an important clean and renewable energy, biomass has a broad market prospect. The dual fluidized bed is widely used in biomass gasification technology, and has become an important way of biomass high-value utilization. This paper describes the basic principle of dual fluidized bed gasification, from the gas composition, tar content and thermal efficiency of the system point of view, analyzes and summarizes several typical dual fluidized bed biomass gasification technologies, points out the existence of gas mixing, the external heat source, catalyst development problems on gas. Finally, it is clear that the gasification of biomass in dual fluidized bed is of great industrial application and development prospect.

  14. Importance of fragmentation on the steady state combustion of wood char in a bubbling fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Pinho, Carlos [Universidade do Porto (CEFT/FEUP), Porto (Portugal). Faculdade de Engenharia. Centro de Estudos de Fenomenos de Transporte], E-mail: ctp@fe.up.pt

    2010-07-01

    A simple mathematical model for the analysis of the steady state behavior of a bubbling fluidized bed burner is presented, with the main intention of evaluating the importance of the primary fragmentation of fuel particles on the performance of this type of burners. This model has pedagogical advantages because of its simplicity and easiness of application to the analysis of realistic situations. The model is based upon the classical models used for the study of batch combustion processes in fluidized bed reactors. Experimental data from studies of fluidized bed combustion of portuguese vegetable chars are used to support the analysis of the performance of a 1 m diameter fluidized bed combustor. (author)

  15. An investigation into the usefulness of different empirical modeling techniques for better control of spray-on fluidized bed melt granulation.

    Science.gov (United States)

    Aleksić, Ivana; Đuriš, Jelena; Ibrić, Svetlana; Parojčić, Jelena

    2015-12-30

    Melt granulation in fluid bed processors is an emerging technique, but literature data regarding the modeling of this granulation method are lacking. In the present study different techniques (response surface analysis, multilayer perceptron neural network, and partial least squares method) were applied for modeling of spray-on fluidized bed melt granulation. Experiments were organized in line with central composite design. The effect of binder content and spray air pressure on granule properties was evaluated. The results obtained indicate that binder content can be identified as a critical factor controlling the granule size and size distribution. It was found that agglomeration mechanism involved, i.e., granule shape, can be greatly influenced by binder properties. The spray air pressure was identified as critical process parameter affecting granule flowability. The results presented indicate that application of in silico tools enables enhanced understanding and better control of novel pharmaceutical processes, such as melt granulation in fluidized bed. The artificial neural networks and partial least squares method were found to be superior to response surface methodology in prediction of granule properties. According to the results obtained, application of more advanced empirical modeling techniques complementary to design of experiments can be a suitable approach in defining the design space and optimization of spray-on fluidized bed melt granulation. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Characterization of products from fluidized-bed combustion of coal.

    Science.gov (United States)

    Bednarik, V; Vondruska, M; Sild, M; Vondruskova, E

    2000-11-01

    The technology of fluidized-bed combustion (FBC) of coal generates byproducts that have a series of unique characteristics and potential uses in technological practice. In this study, the products of fluidized-bed combustion (FBC-P) of coal derived from Moravian heat stations, a.s. Zlin, Cinergy Global Resources, Czech Republic, were characterized. Particular attention was paid to determining the chemical composition of FBC-P, the content of polycyclic aromatic hydrocarbons (PAHs) and toxic metals in the water leachates of these FBC-P, the content of unburned carbon, the capability of FBC-P to solidify with water and form a solid matrix, and the method for discovering optimum mixing water content for FBC-P solidification. The results suggest that one of the qualitatively more important means of utilizing FBC-P could be their application during solidification/stabilization (S/S) of wastes, particularly wastewater treatment sludges.

  17. Carbon Shale Combustion in the Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Olek Małgorzata

    2014-06-01

    Full Text Available The purpose of this article is to present the possibilities of coal shale combustion in furnaces with bubbling fluidized bed. Coal shale can be autothermally combusted in the fluidized bed, despite the low calorie value and high ash content of fuel. Established concentrations of CO (500 ppm and VOC (30 mg/m3 have indicated a high conversion degree of combustible material during combustion process. Average concentrations of SO2 and NOx in the flue gas were higher than this received from the combustion of high quality hard coal, 600 ppm and 500 ppm, respectively. Optional reduction of SO2 and NOx emission may require the installation of flue gas desulphurization and de-NOx systems.

  18. Combustion of Jordanian oil shale using circulating fluidized bed

    International Nuclear Information System (INIS)

    Hamdan, M.; Al-Azzam, S.

    1998-11-01

    this study re[resents design and manufacturing of a lab-scale circulating fluidized bed (C.F.B) to burn low grade fuel such as Jordanian oil shale. Hydrodynamic properties of C.F.B. were studied like minimum fluidization velocity, circulation flux and carryover rate. a hot run was firstly conducted by the combustion of L.P.G. to start up the combustion process. It proceeds until reaching the minimum burning temperature of oil shale particles, at which time the LPG supply was gradually reduced and oil shale feeding started. soon after reaching a self sustainable condition of oil shale particles, the LPG supply was cut off. The main combustion variables were investigated such as air to fuel ratios, temperature profiles across the bed, exhaust gas analysis and combustion efficiency. a combustion intensity of 859 kg/hr.m 2 and combustion efficiency of 96% were achieved. (authors). 19 refs., 9 tab., 18 fig

  19. A computational fluid dynamic model for fluidized bed heat transfer

    International Nuclear Information System (INIS)

    Yusuf, R.; Melaaen, M.C.; Mathiesen, V.

    2005-01-01

    The objective of this work is to study heat transfer from a heated wall in a gas fluidized bed using the computational fluid dynamic (CFD) approach. An Eulerian-Eulerian simulation of a two dimensional bubbling bed at ambient conditions with a heated wall is carried out on the in-house code FLOTRACS-MP-3D. An empirical as well as a mechanistic model for solid phase thermal conductivity is tested. Effect of operating parameters like velocity and particle size are also investigated. The fluid dynamic model is able to predict the qualitative trends for the influence of operating parameters as well as high heat transfer coefficients observed in gas fluidized beds. (author)

  20. Combustion of refuse derived fuel in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Guilin; Aono, Shigeru; Mori, Shigekatsu; Deguchi, Seiichi; Fujima, Yukihisa [Nagoya Univ. (Japan); Kondoh, Motohiro; Yamaguchi, Masataka [Toyota Motor Corp. (Japan). Plant Engineering Dept.

    1998-12-31

    Power generation from Refuse Derived Fuel (RDF) is an attractive utilization technology of municipal solid waste. To explain the behavior of RDF-fired fluidized bed incinerator, the commercial size RDF was continuously burnt in a 30 x 30 cm bubbling type fluidized-bed combustor. It was found that 12 kg/h of RDF feed rate was too high feed for this test unit and the Co level was higher than 500 ppm. However, 10 kg/h of RDF was a proper feed rate and the Co level was kept under 150 ppm. Secondary air injection and changing air ratio from the pipe grid were effective for the complete combustion of RDE. It was also found that HCl concentration in flue gas was controlled by the calcium component contained in RDF and its level was decreased with decreasing the combustor temperature.

  1. Biological reduction of nitrate wastewater using fluidized-bed bioreactors

    International Nuclear Information System (INIS)

    Walker, J.F. Jr.; Hancher, C.W.; Patton, B.D.; Kowalchuk, M.

    1981-01-01

    There are a number of nitrate-containing wastewater sources, as concentrated as 30 wt % NO 3 - and as large as 2000 m 3 /d, in the nuclear fuel cycle as well as in many commercial processes such as fertilizer production, paper manufacturing, and metal finishing. These nitrate-containing wastewater sources can be successfully biologically denitrified to meet discharge standards in the range of 10 to 20 gN(NO 3 - )/m 3 by the use of a fluidized-bed bioreactor. The major strain of denitrification bacteria is Pseudomonas which was derived from garden soil. In the fluidized-bed bioreactor the bacteria are allowed to attach to 0.25 to 0.50-mm-diam coal particles, which are fluidized by the upward flow of influent wastewater. Maintaining the bacteria-to-coal weight ratio at approximately 1:10 results in a bioreactor bacteria loading of greater than 20,000 g/m 3 . A description is given of the results of two biodenitrification R and D pilot plant programs based on the use of fluidized bioreactors capable of operating at nitrate levels up to 7000 g/m 3 and achieving denitrification rates as high as 80 gN(NO 3 - )/d per liter of empty bioreactor volume. The first of these pilot plant programs consisted of two 0.2-m-diam bioreactors, each with a height of 6.3 m and a volume of 208 liters, operating in series. The second pilot plant was used to determine the diameter dependence of the reactors by using a 0.5-m-diam reactor with a height of 6.3 m and a volume of 1200 liters. These pilot plants operated for a period of six months and two months respectively, while using both a synthetic waste and the actual waste from a gaseous diffusion plant operated by Goodyear Atomic Corporation

  2. The grinding of uranium dioxide from fluidized beds

    International Nuclear Information System (INIS)

    Alonso Folgueras, J. A.

    1974-01-01

    This work deals with the UO 2 vibratory grinding, the UO 2 obtained from fluidized beds. In this study the grinding time has been correlated with surface area, stoichiometry, granulometry and grinded product contamination. The efficiency losses in the grinding of moisten UO 2 are outlined. Finally it is made a brief study of the granulate obtained from the grinded UO 2 as well as the green pellets resulting from it, taking into consideration the dispersion of its density and height. (Author)

  3. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project. 1990 Annual report

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  4. Fluidized bed reactor for working up carbon coated particles

    International Nuclear Information System (INIS)

    Marschollek, M.; Simon, W.; Walter, C.

    1981-01-01

    A fluidized bed reactor is described for working up carbon coated particles, particularly nuclear fuel particles or fertile material particles consisting essentially of a cylindrical portion connected to a conical portion. Gas supply pipes, gas distribution space and gas distribution heads are provided within the conical reactor lower portion, the gas distribution members being arranged in at least two superimposed planes and distributed symmetrically over the cross-section of the reactor

  5. Gasification of wood in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, L.C. de; Marti, T.; Frankenhaeuser, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A first series of gasification experiments with our fluidized bed gasifier was performed using clean sawdust as fuel. The installation and the analytical systems were tested in a parametric study in which gasification temperature and equivalence ratio were varied. The data acquired will serve to establish the differences between the gasification of clean wood and the gasification of Altholz (scrapwood) and wood/plastics mixtures. (author) 1 fig., 3 tabs., 5 refs.

  6. Spectral methods applied to fluidized bed combustors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R.C.; Christofides, N.J.; Junk, K.W.; Raines, T.S.; Thiede, T.D.

    1996-08-01

    The objective of this project was to develop methods for characterizing fuels and sorbents from time-series data obtained during transient operation of fluidized bed boilers. These methods aimed at determining time constants for devolatilization and char burnout using carbon dioxide (CO{sub 2}) profiles and from time constants for the calcination and sulfation processes using CO{sub 2} and sulfur dioxide (SO{sub 2}) profiles.

  7. Fluid-dynamic behavior of flaxseed fluidized and spouted bed

    Directory of Open Access Journals (Sweden)

    Elza Brandão Santana

    2017-09-01

    Full Text Available ABSTRACT: Processing of particles in a moving bed, such as a fluidized bed or a spouting bed, is commonly used in the operations of drying, coating, and granulation of particulate systems. This process has applications in the chemical, pharmaceutical and, presently, agronomical industries, especially for seed treatment/coating. This research aimed to analyze the fluid-dynamic behavior of fluidized and spouting beds with different air temperatures and loads of flaxseeds (Linum usitatissimum L., with estimates of the fluid-dynamic parameters correlated to each process. The parameters were compared with the values obtained from classical correlations in the literature, with indications of associated percentages of deviation. Influence of fluid dynamics on the physiological quality of seeds was assessed by germination tests and the germination speed index. An analysis of the results indicated that seed processing was adequate for processing in dynamically active beds; however, temperatures above 50ºC in both beds caused significant reductions in the physiological quality of the seeds. Processing in a fluidized bed presented a smaller reduction of the physiological properties of the flaxseed.

  8. Modelling of dynamics of combustion of biomass in fluidized beds

    Directory of Open Access Journals (Sweden)

    Saastamoinen Jaakko J.

    2004-01-01

    Full Text Available New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.

  9. Collaborative research on fluidization employing computer-aided particle tracking

    International Nuclear Information System (INIS)

    Chen, M.M.

    1990-01-01

    The objective of this work is to obtain unique, fundamental information on fluidization dynamics over a wide range of flow regimes using a Transportable Computer-Aided Particle Tracking Apparatus (TCAPTA). The contractor will design and fabricate a transportable version of the Computer-Aided Particle Tracking Facility (CAPTF) he has previously developed. The contractor will install and operate the (TCAPTA) at the METC fluidization research facilities. Quantitative data on particle motion will be obtained and reduced. The data will be used to provide needed information for modeling of bed dynamics, and prediction of bed performance, including erosion. A radioactive tracer particle, identical in size shape and mass to the bed particles under study, is mixed in the bed. The radiation emitted by the tracer particle, monitored continuously by 16 scintillation detectors, allows its position to be determined as a function of time. Stochastic mixing processes intrinsic to fluidization further cause the particle to travel to all active regions of the bed, thus sampling the motion in these regions. After a long test run to insure that a sufficient sampling have been acquired, time-differentiation and other statistical processing will then yield the mean velocity distribution, the fluctuating velocity distribution, many types of auto- and cross correlations, as well as mean fluxes, including the mean momentum fluxes due to random motion, which represent the kinetic contributions to the mean stress tensor

  10. The heat transfer mechanisms in fluidized beds; Laemmoensiirtomekanismit leijukerroksessa

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Blomster, A.M.; Kojola, H. [Helsinki Univ. of Technology, Espoo (Finland)

    1996-12-01

    The goal of the research project is to improve the accuracy of the heat transfer correlation in circulating fluidized beds and to define how the heat transfer is distributed in radiation and convection in the different parts of the fluidized bed. This will be carried out by studying the behaviour and heat transfer of the fluidized bed in the boundary layer near the wall. The total and radiative heat transfer as well as the particle concentration will be measured. Based on the data a correlation will be created. Two different measurement systems are used. The particle concentration is measured by a image-analysis system. A video camera and a Super VHS recorder are used to capture live images from the bed. The images are digitized and stored on a PC. The system has been used in previous research projects at our laboratory. In earlier projects all measurements have been carried out in cold environments. In this project the system will be modified for hot environments. The radiative heat transfer is measured by a radiative heat transfer probe connected to a PC via an A/D converter. The probe consists of a heat flow detector which is isolated from the bed by a sapphire window so that only the radiative part of the heat transfer is detected. The probe will be calibrated in a black body oven so that the effect of the conduction and the sapphire window can be separated. (author)

  11. Tar removal during the fluidized bed gasification of plastic waste.

    Science.gov (United States)

    Arena, Umberto; Zaccariello, Lucio; Mastellone, Maria Laura

    2009-02-01

    A recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850 degrees C, the equivalence ratio varied between 0.2 and 0.35, the amount of bed material was between 131 and 215 kg, the fluidizing velocity was between 0.5 and 0.7 m/s, quartz sand and olivine were used as bed material, and air and steam were used as fluidizing reactants. The results confirm that the tar removal treatments applied inside the gasifier (primary methods) can eliminate or strongly reduce the need for a further downstream cleanup of the syngas. In particular, the utilization of a natural olivine as an in situ tar reduction agent remarkably improves the quality of the product gas, in terms of both high hydrogen volumetric fraction and larger syngas yield.

  12. Coupled Inverse Fluidized Bed Bioreactor with Advanced Oxidation Processes for Treatment of Vinasse

    Directory of Open Access Journals (Sweden)

    Karla E. Campos Díaz

    2017-11-01

    Full Text Available Vinasse is the wastewater generated from ethanol distillation; it is characterized by high levels of organic and inorganic matter, high exit temperature, dissolved salts and low pH. In this work the treatment of undiluted vinasse was achieved using sequentially-coupled biological and advanced oxidation processes. The initial characterization of vinasse showed a high Chemical Oxygen Demand (COD, 32 kg m-3, high Total Organic Carbon (TOC, 24.5 kg m-3 and low pH (2.5. The first stage of the biological treatment of the vinasse was carried out in an inverse fluidized bed bioreactor with a microbial consortium using polypropylene as support material. The fluidized bed bioreactor was kept at a constant temperature (37 ± 1ºC and pH (6.0 ± 0.5 for 90 days. After the biological process, the vinasse was continuously fed to the photoreactor using a peristaltic pump 2.8 × 10-3 kg of FeSO4•7H2O were added to the vinasse and allowed to dissolve in the dark for five minutes; after this time, 15.3 m3 of hydrogen peroxide (H2O2 (30% w/w were added, and subsequently, the UV radiation was allowed to reach the photoreactor to treat the effluent for 3600 s at pH = 3. Results showed that the maximum organic matter removed using the biological process, measured as COD, was 80% after 90 days. Additionally, 88% of COD removal was achieved using the photo-assisted Fenton oxidation. The overall COD removal after the sequentially-coupled processes reached a value as low as 0.194 kg m-3, achieving over 99% of COD removal as well as complete TOC removal.

  13. An aerated and fluidized bed membrane bioreactor for effective wastewater treatment with low membrane fouling

    KAUST Repository

    Ye, Yaoli

    2016-09-24

    Anaerobic fluidized bed membrane bioreactors (AFMBRs) use granular activated carbon (GAC) particles suspended by recirculation to effectively treat low strength wastewaters (∼100–200 mg L−1, chemical oxygen demand, COD), but the effluent can contain dissolved methane. An aerobic fluidized bed membrane bioreactor (AOFMBR) was developed to avoid methane production and the need for wastewater recirculation by using rising air bubbles to suspend GAC particles. The performance of the AOFMBR was compared to an AFMBR and a conventional aerobic membrane bioreactor (AeMBR) for domestic wastewater treatment over 130 d at ambient temperatures (fixed hydraulic retention time of 1.3 h). The effluent of the AOFMBR had a COD of 20 ± 8 mg L−1, and a turbidity of <0.2 NTU, for low-COD influent (153 ± 19 and 214 ± 27 mg L−1), similar to the AeMBR and AFMBR. For the high-COD influent (299 ± 24 mg L−1), higher effluent CODs were obtained for the AeMBR (38 ± 9 mg L−1) and AFMBR (51 ± 11 mg L−1) than the AOFMBR (26 ± 6 mg L−1). Transmembrane pressure of the AOFMBR increased at 0.04 kPa d−1, which was 20% less than the AeMBR and 57% less than the AFMBR, at the low influent COD. Scanning electron microscopy (SEM) analysis indicated a more uniform biofilm on the membrane in AOFMBR than that from the AeMBR biofilm, and no evidence of membrane damage. High similarity was found between communities in the suspended sludge in the AOFMBR and AeMBR (square-root transformed Bray–Curtis similarity, SRBCS, 0.69). Communities on the GAC and suspended sludge were dissimilar in the AOFMBR (SRBCS, 0.52), but clustered in the AFMBR (SRBCS, 0.63).

  14. Modelling fluidized catalytic cracking unit stripper efficiency

    OpenAIRE

    García-Dopico M.; García A.

    2015-01-01

    This paper presents our modelling of a FCCU stripper, following our earlier research. This model can measure stripper efficiency against the most important variables: pressure, temperature, residence time and steam flow. Few models in the literature model the stripper and usually they do against only one variable. Nevertheless, there is general agreement on the importance of the stripper in the overall process, and the fact that there are few models maybe i...

  15. A two-stage fixed-bed reactor for direct hydrotreatment of volatiles from the hydropyrolysis of biomass: effect of catalyst temperature, pressure and catalyst ageing time on product characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pindoria, R.V.; Megaritis, A.; Herod, A.A.; Kandiyoti, R. [Imperial College of Science, Technology and Medicine, London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology

    1998-12-01

    This investigation involved the hydropyrolysis of biomass (eucalyptus globulus) and the immediate catalytic hydrocracking of pyrolytic oils in the second stage of the reactor. The effects of temperature, pressure and the catalyst ageing time on the final product tar have been studied using the catalyst Zeolite H-ZSM5. The catalytically hydrocracked tar/oil products were characterised and compared with the hydropyrolysis product from the first stage of the reactor to determine the effect of catalytic hydrocracking. The carbon deposition on the catalyst has been examined using thermogravimetric analysis. The tar yields after catalytic hydrocracking decreased with increasing pressure and temperature of the cracking stage. The tar yields at 10 bar pressure were greater than those at 40 bar pressure. The fresh zeolite catalyst trapped more than 40% of the product from the hydropyrolysis stage and TGA evidence indicated that this was not as carbon deposition but as volatiles trapped in the zeolite matrix. Reuse of the catalyst resulted in little more uptake of volatiles; however, extended use of the catalyst did not result in increased yields of liquid products but in increased production of light volatiles or gas. The H-ZSM5 catalyst appeared to act as a more active cracking catalyst rather than to promote hydrogenation or deoxygenation of the liquids produced in the hydropyrolysis stage. Characterisation of the liquids by SEC and UV fluorescence indicated that structural changes were relatively minor despite the significant changes in yields of liquids with process conditions. Available reaction routes do not appear to allow specific deoxygenation pathways to predominate without disintegration of parent molecules to lighter volatiles, under the conditions used here. 41 refs., 10 figs., 4 tabs.

  16. Selective catalytic reduction of nitrogen oxide with ammonia in a novel reactor called the floating gas-solid fluidized bed

    NARCIS (Netherlands)

    Kwant, G.J.; Kwant, G.J.; Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1995-01-01

    The floating gas-solid fluidized bed (FGSFB) is a new type of gas-solid contacting device described earlier by Kwant et al. (Fluidization VII, Proc. 7th Engng Foud. Conf. on Fluidization, Brisbane, May, 1992). It is a tapered column provided with several coarse grids, in which catalyst particles are

  17. Dynamic Flow Behavior Measurements in Gas-Solid Fluidized Beds Using Different Non-Intrusive Techniques and Polyethylene Powder

    Science.gov (United States)

    Wu, Bangyou; Yu, Guang; Bellehumeur, Celine; Kantzas, Apostolos

    2007-06-01

    Pressure fluctuations and X-ray computed tomography (CT) measurements were utilized to characterize the flow behavior of gas-solid fluidized beds using polyethylene particles in three Plexiglas columns with diameters of 10cm, 20cm, and 30cm. Air was used as the gas phase. Gas-solids flow dynamic under ambient conditions was characterized from statistical analysis of pressure fluctuation data and CT images. The time-averaged voidage distribution, bubble phase area fraction, bubble diameter and bubble number distribution varying with the bed heights were extracted from all the three columns. Bed scales had significant effect on the hydrodynamics. Scale up effects on the gas-solids two-phase flow behavior were discussed.

  18. Discrete particle simulations of an electric-field enhanced fluidized bed

    NARCIS (Netherlands)

    Kleijn van Willigen, F.; Demirbas, B.; Deen, N.G.; Kuipers, J.A.M.; Ommen, J.R.

    2008-01-01

    Reducing the size of gas bubbles can significantly improve the performance of gas–solid fluidized reactors. However, such a control of bubbles is difficult to realize without measures that either use a lot of energy or deteriorate the fluidization behavior. In this paper, we present the results of

  19. Investigation of the particle flowpattern and segregation in tapered fluidized bed granulators

    NARCIS (Netherlands)

    Schaafsma, S. H.; Marx, T.; Hoffmann, A. C.

    The particle flowpattern and granule segregation in tapered fluidized beds have been studied using two techniques. The first technique is to fluidize beds of varying total mass and granule fractions, then defluidize them suddenly to "freeze" the composition, section the bed in layers, and determine

  20. Discrete element study of granulation in a spout-fluidized bed

    NARCIS (Netherlands)

    Link, J.M.; Godlieb, W.; Deen, N.G.; Kuipers, J.A.M.

    2007-01-01

    In this work a discrete element model (DEM) is presented for the description of the gas–liquid–solid flow in a spout-fluidized bed including all relevant phenomena for the study of granulation. The model is demonstrated for the case of a granulation process in a flat spout-fluidized bed, containing

  1. Discrete element modeling and fibre optical measurements for fluidized bed spray granulation

    NARCIS (Netherlands)

    Link, J.M.; Godlieb, W.; Deen, N.G.; Heinrich, S.; Tripp, P.; Peglow, M.; Kuipers, J.A.M.; Schönherr, M.; Mörl, L.

    2007-01-01

    Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties,

  2. Characterization of granular phase change materials for thermal energy storage applications in fluidized beds

    International Nuclear Information System (INIS)

    Izquierdo-Barrientos, M.A.; Sobrino, C.; Almendros-Ibáñez, J.A.; Barreneche, C.; Ellis, N.; Cabeza, L.F.

    2016-01-01

    Highlights: • Granular PCMs are tested in 3D and 2D fluidized beds. • Density, particle size and angle of repose were measured for different granular PCMs. • DSC measurements confirm that there is no loss of material after fluidization. - Abstract: This work investigates commercially available granular phase change materials (PCMs) with different transition temperatures for the use of thermal-energy storage systems in fluidized beds. The hydrodynamic characteristics of granular PCMs were tested in cylindrical-3D and planar-2D fluidized beds. The density, particle size distribution and angle of repose were measured for various PCM materials. Further attrition studies were conducted with changes in particle surface from abrasion, which were characterized using a Scanning Electron Microscope (SEM). The results indicate that some materials with smaller particle size and thinner supporting structure can lose the paraffin during the fluidization process, when paraffin is in a liquid state. As a consequence, the particles agglomerate, and the bed defluidizes. For all of the tested materials, only GR50 (with a transition temperature of 50 °C) properly fluidizes when the paraffin is in the liquid state and has shown to endure >75 h of continuous operation and 15 melting-solidification cycles in a fluidized bed. Additional differential scanning calorimetry (DSC) measurements of the cycled particles did not show a decrease in energy storage capacity of the granular PCM, which corroborates that there is no loss of material after >75 h of fluidization.

  3. Mathematical modeling of a fluidized bed rice husk gasifier: Part 2 - Model sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Mansaray, K.G.; Ghaly, A.E.; Al-Taweel, A.M.; Hamdullahpur, F.; Ugursal, V.I.

    2000-02-01

    The performance of two thermodynamic models (one-compartment and two-compartment models), developed for fluidized bed gasification of rice husk, was analyzed and compared in terms of their predictive capabilities of the product gas composition. The two-compartment model was the most adequate to simulate the fluidized bed gasification of rice husk, since the complex hydrodynamics present in the fluidized bed gasifier were taken into account. Therefore, the two-compartment model was tested under a wide range of parameters, including bed height, fluidization velocity, equivalence ratio, oxygen concentration in the fluidizing gas, and rice husk moisture content. The model sensitivity analysis showed that changes in bed height had a significant effect on the reactor temperatures, but only a small effect on the gas composition, higher heating value, and overall carbon conversion. The fluidization velocity, equivalence ratio, oxygen concentration in the fluidizing gas, and moisture content in rice husk had dramatic effects on the gasifier performance. However, the model was more sensitive to variations in the equivalence ratio and oxygen concentration in the fluidizing gas. (Author)

  4. Mathematical modeling of a fluidized bed rice husk gasifier: Part 2 -- Model sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Mansaray, K.G.; Ghaly, A.E.; Al-Taweel, A.M.; Hamdullahpur, F.; Ugursal, V.I.

    2000-03-01

    The performance of two thermodynamic models (one-compartment and two-compartment models), developed for fluidized bed gasification of rice husk, was analyzed and compared in terms of their predictive capabilities of the product gas composition. The two-compartment model was the most adequate to simulate the fluidized bed gasification of rice husk, since the complex hydrodynamics present in the fluidized bed gasifier were taken into account. Therefore, the two-compartment model was tested under a wide range of parameters, including bed height, fluidization velocity, equivalence ratio, oxygen concentration in the fluidizing gas, and rice husk moisture content. The model sensitivity analysis showed that changes in bed height had a significant effect on the reactor temperatures, but only a small effect on the gas composition, higher heating value, and overall carbon conversion. The fluidization velocity, equivalence ratio, oxygen concentration in the fluidizing gas, and moisture content in rice husk had dramatic effects on the gasifier performance. However, the model was more sensitive to variations in the equivalence ratio and oxygen concentration in the fluidizing gas.

  5. 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

  6. Volatiles combustion in fluidized beds. Final technical report, 4 September 1992--4 June 1995

    Energy Technology Data Exchange (ETDEWEB)

    Pendergrass, R.A. II; Raffensperger, C.; Hesketh, R.P.

    1996-02-29

    The goal of this project is to investigate the conditions in which volatiles will burn within both the dense and freeboard regions of fluidized beds. Experiments using a fluidized bed operated at incipient fluidization are being conducted to characterize the effect of particle surface area, initial fuel concentration, and particle type on the inhibition of volatiles within a fluidized bed. A review of the work conducted under this grant is presented in this Final Technical Report. Both experimental and theoretical work have been conducted to examine the inhibition of the combustion by the fluidized bed material, sand. It has been shown that particulate phase at incipient fluidization inhibits the combustion of propane by free radical destruction at the surface of sand particles within the particulate phase. The implications of these findings is that at bed temperatures lower than the critical temperatures, gas combustion can only occur in the bubble phase or at the top surface of a bubbling fluidized bed. In modeling fluidized bed combustion this inhibition by the particulate phase should be included.

  7. The influence of transport phenomena on the fluidized bed combustion of a single carbon particle

    NARCIS (Netherlands)

    Prins, W.; van Swaaij, Willibrordus Petrus Maria

    1990-01-01

    The burning rate and temperature of the carbon particles are known to affect the efficiency of a fluidized bed combustor, and also the emission levels of undesired noxious components. The main results of an extensive study on the fluidized bed combustion behaviour of a single carbon particle [1] are

  8. The combustion of low calorific value fuels (oil shale) by using fluidized bed combustor

    International Nuclear Information System (INIS)

    Azzam, S.M.

    1993-01-01

    The present work reports an experimental data for combustion of oil-shale in a fluidized bed combustor. The experimental set up was designed for the combustion of low calorific value fuel such as oil-shale to facilitate the variation of many parameters over a wide operating range. A cold run was firstly conducted to study the fluidization parameters. Fluidization experiment were made with different sized quartiz particles. Minimum fluidization velocities and other fluidization characteristics were determined at room temperature. Secondary a hot run was started, first studying the combustion of 'LPG' in a fluidized bed as a starting process, then studying the combustion if oil-shale with different flow rates. The experimetal results are promising and give rise to hopes that this valuable deposit can be used as a fuel source and can be burned sucessfully in a fluidized bed combustor. This study had prooved that utilization of oil-shale a fuel source is no more a complicated technical problem, this opens the way for power generation using fluidized bed combustors. (author). 17 refs., 32 figs., 3 tabs

  9. Combining fluidized activated carbon with weak alternating electric fields for disinfection

    NARCIS (Netherlands)

    Racyte, J.; Sharabati, J.; Paulitsch-Fuchs, A.H.; Yntema, D.R.; Mayer, M.J.J.; Bruning, H.; Rijnaarts, H.H.M.

    2011-01-01

    This study presents fluidized bed electrodes as a new device for disinfection. In the fluidized bed electrodes system, granular activated carbon particles were suspended, and an alternating radio frequency electric field was applied over the suspended bed. Proof-of-principle studies with the

  10. Effects of the DASH-JUMP dietary intervention in Japanese participants with high-normal blood pressure and stage 1 hypertension: an open-label single-arm trial

    OpenAIRE

    Kawamura, Atsuko; Kajiya, Katsuko; Kishi, Hiroko; Inagaki, Junko; Mitarai, Makoto; Oda, Hiroshi; Umemoto, Seiji; Kobayashi, Sei

    2016-01-01

    The Dietary Approaches to Stop Hypertension (DASH) diet is recommended by the American Heart Association to lower blood pressure (BP); however, its effects in Japanese participants have not been rigorously studied. We assessed the effects of the DASH-Japan Ube Modified diet Program (DASH-JUMP), a modified DASH diet, on cardiometabolic and inflammatory biomarkers in Japanese participants with untreated high-normal BP or stage 1 hypertension. Fifty-eight participants (30 men and 28 women; mean ...

  11. Conversion of ammonium uranyl carbonate to UO2 in a fluidized bed

    International Nuclear Information System (INIS)

    Zhao Jun; Qiu Lufu; Zhong Xing; Xu Heqing

    1989-11-01

    The conversion of AUC (Ammonium Uranyl Carbonate) to UO 2 was studied in a fluidized bed of 60 mm inner diameter based on the thermodynamics and kinetics data of decomposition-reduction of AUC. The influence of the reaction temperature, composition of fluidization gas and fluidization velocity on conversion were investigated by using N 2 , Ar and circulation gas (mixing gas of H 2 and CO obtained from the exhaust gas of the decomposition of AUC by catalyst crack-conversion) as the fluidization gas. The throughput is up to the high levels (3.32 kg(wet)/h·L) by using circulation gas or mixing of circulation gas and Ar (< 21%) as the fluidization gas when the reaction temperature exceeds 570 deg C

  12. PENGARUH MASSA JENIS PARTIKEL DAN KETINGGIAN PARTIKEL TERHADAP FENOMENA FLUIDISASI DALAM FLUIDIZED BED DENGAN MENGGUNAKAN CFD

    Directory of Open Access Journals (Sweden)

    Rosyida Permatasari

    2016-12-01

    Full Text Available Fenomena fluidisasi pada fluidized bed yaitu kecepatan minimum dan tekanan statis partikel merupakan hal fenomena yang penting dalam desain fluidized bed. Fenomena-fenomena tersebut dipengaruhi oleh banyak faktor dalam fluidized bed diantaranya massa jenis dan tinggi partikel di dalam fluidized bed. Penelitian ini menggunakan jenis partikel yang berbeda-beda dan rasio ketinggian partikel terhadap diameter fluidized bed (H/D dengan menggunakan Computational Fluid Dynamics. Partikel yang digunakan adalah partikel dengan jenis Geldart B yaitu glass beads (ρ=2600 kg/m3, ground walnut shell (ρ=1200 kg/m3 dan ground corncob (ρ=800 kg/m3, sedangkan rasio ketinggian partikel yang digunakan yaitu 0.5, 1, 1.5, 2, dan 2.5. Hasil penelitian menunjukkan bahwa massa jenis partikel berbanding lurus dengan kecepatan minimum fluidisasi dan ketinggian partikel tidak mempengaruhi kecepatan minimum fluidisasi.

  13. An Euler–Euler approach to modeling biomass fast pyrolysis in fluidized-bed reactors – Focusing on the gas phase

    International Nuclear Information System (INIS)

    Mellin, Pelle; Zhang, Qinglin; Kantarelis, Efthymios; Yang, Weihong

    2013-01-01

    A developed 3D Euler–Euler CFD model, with an integrated pyrolysis model, is proposed as a way of predicting vapor phase dynamics and product distributions in the fluidized bed process for biomass fast pyrolysis. The main interest in this work is the gases resulting from the pyrolysis mixed with the fluidizing gas. We propose therefore a simple rendering of the solid material while directing attention to the vapor phase. At the same time the required computational resources for reaching stabilized conditions in the reactor are reduced. Temperature profile, velocity profile and pyrolysis products are predicted and globally verified by a series of parallel cases, which are compared to experimental measurements and known trends of liquid, solid and gas yields. The comparison of experimental measurements and model predictions satisfy the accuracy of the model and on a quantitative basis, the product yields agree with commonly known trends of bio oil versus temperature and residence time. -- Highlights: • A 3-D CFD model for fast pyrolysis in fluidized beds has been developed. • Focus is on the vapor phase which permits a simplified rendering of the solids. • Predicted results largely agree with measured temperature, pressure, and bed height

  14. Heat transfer from a horizontal finned tube bundle in bubbling fluidized beds of small and large particles

    Energy Technology Data Exchange (ETDEWEB)

    Devaru, C.B. [Jayachamaraja College of Engineering, Mysore (India). Dept. of Mechanical Engineering; Kolar, A.K. [Indian Inst. of Technology, Madras (India). Dept. of Mechanical Engineering

    1995-12-31

    Steady state average heat transfer coefficient measurements were made by the local thermal simulation technique in a cold, square, bubbling air-fluidized bed (0.305 m x 0.305 m) with immersed horizontal finned tube bundles (in-line and staggered) with integral 60{degree} V-thread. Studies were conducted using beds of small (average particle diameter less than 1 mm) sand particles and of large (average particle diameter greater thin 1 mm) particles (raagi, mustard, millet and coriander). The fin pitch varied from 0.8 to 5.0 mm and the fin height varied from 0.69 to 4.4 mm. The tube pitch ratios used were 1.75 and 3.5. The influence of bed particle diameter, fluidizing velocity, fin pitch, and tube pitch ratio on average heat transfer coefficient was studied. Fin pitch and bed particle diameter are the most significant parameters affecting heat transfer coefficient within the range of experimental conditions. Bed pressure drop depends only on static bed height. New direct correlations, incorporating easily measurable quantities, for average heat transfer coefficient for finned tube bundles (in-line and staggered) are proposed.

  15. Thermofluid effect on energy storage in fluidized bed reactor

    Science.gov (United States)

    Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

    2016-05-01

    The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  16. Fluidized bed granulation of an ordered powder mixture.

    Science.gov (United States)

    Thiel, W J; Nguyen, L T

    1982-11-01

    The phenomenon of ordered unit segregation is of paramount importance in determining the homogeneity of an ordered mixture. This problem can be avoided by using a monodisperse carrier, but it is uneconomic. The fluidized bed granulation of a 0.1% ordered mixture has been studied as a method of reducing the effects of segregation. The ordered units were stable when fluidized and no significant loss of the microfine adsorbed material occurred during processing. The distribution of the minor component in the granules was significantly more uniform than in the original ordered mixtures. The demixing potential (formula: see text) (where p = proportion of cohesive minor component and w is the weight % of carrier material in a particular size range) was used to quantify the distribution of the minor component as a function of particle size. DP is a coefficient of variation and can be directly compared with the specification standard deviation sigma A. Batches of granules were compressed into 100 or 350 mg tablets, containing approximately 100 and 350 micrograms of model drug substance. The weight and content coefficients of variation (c.v.) were determined for 20 tablets. All batches had a weight c.v. less than or equal to 1.5% and a content c.v. less than or equal to 4.6%. Granulation of an ordered mixture greatly reduces the potential for segregation to decrease the mixture homogeneity. It also provides a solution to the problems which may be encountered when the mixing of small quantities of cohesive materials during conventional fluidized bed granulation is attempted.

  17. Retrieval of fluidizable radioactive wastes from storage facilities

    International Nuclear Information System (INIS)

    2006-08-01

    This report provides guidance for strategic planning and implementation of resuspension and retrieval of stored fluid or fluidizable radioactive wastes. The potential risks associated with preparation and realization of these processes are included in the report, and lessons learned from previous applications are highlighted. Technological procedures and equipment used in various countries for resuspension and remobilization of stored fluidizable radioactive wastes are described in the attached annexes as potential options. Waste retrieval is a maturing technology of major importance now that Member States are moving forward in the responsible management of wastes by removal to safe interim storage or disposal. Retrieval of fluidizable wastes is a four-phase operation: (1) access to the waste, (2) mobilize the waste, (3) remove the waste; and (4) transfer the waste.This report divides successful retrieval of radioactive waste into two areas. The first area applies the concept of the waste retrieval as being the final component of a systematic process of old waste management. It also encompasses characterization as it applies to waste retrieval and downstream processes, including acceptance of wastes for treatment, conditioning, storage or disposal. It should be in conformity with national policy, as well as complying with international safety standards and environmental agreements. The second area of the report focuses on implementation of waste retrieval in a wide range of scenarios and using a wide range of retrieval approaches, equipment and technologies. Technical processes are further explained as part of the experience gained in advanced countries on the subject. A set of detailed retrieval technology descriptions by country is included as Annexes to this report. Thirteen experts from seven Member States that previously implemented, or have planned for the near future, significant resuspension and remobilization operations were involved in the preparation of

  18. Materials support for EPRI Fluidized-Bed Combustion Program

    International Nuclear Information System (INIS)

    Sethi, V.K.; Wright, I.G.

    1993-05-01

    This research project was intended to provide technical support for materials aspects of EPRI's U.C. Fluidized Bed Combustor Program. The scope of this support included participation in the EPRI FBC materials oversight panel, inspection of fluidized beds during forced or planned outages, analysis of materials failures and of associated deposits, participation in technical meetings involving fluidized bed materials. Volume I describes the results of exposing for approximately 5,000 hours in the Georgetown AFBC a number of surface modifications that had been reported to have promise in combating in-bed evaporator tube wastage. Some measures were applied to sample lengths of carbon-steel tubing, and installed as part of the in-bed evaporator tube bundle at Georgetown. These tubes are inspected periodically while still installed in the unit, and were finally cut out and subjected to detailed measurements and metallographic evaluation. The exposure at regular intervals throughout the bed of plain carbon-steel tubes that were honed and surface-ground allowed a baseline measurement of the wastage potential of this bed, which was high. Qualitatively, all but one of the protective measures tested reduced wastage. The unprotected tubes showed that wastage occurred mainly on the underside of the tubes, with maximum wear at the tube bottom. The protective measures that were exposed were densely studded tubes, fins and flow separators, fins and studs on the underside of the tube, and longitudinal rods. These surface modifications were exposed in the chromized and unchromized conditions, together with plain carbon-steel tubes that had been chromized. The tubes with fins and flow separators exhibited continued wastage on the underside between the flow separators, which was attributed in part to the steep inclination of the tubes in the bed. The plain, chromized tubes, together with the armored, chromized tubes, exhibited virtually no wastage of the tube surface nor of the armor

  19. Tunguska, 1908: the gas pouch and soil fluidization hypothesis

    Science.gov (United States)

    Nistor, I.

    2012-01-01

    The Siberian taiga explosion of 30 June 1908 remains one of the great mysteries of the 20th century: millions of trees put down over an area of 2200 km2 without trace of a crater or meteorite fragments. Hundred years of failed searches have followed, resulting in as many flawed hypothesis which could not offer satisfactory explanations: meteorite, comet, UFO, etc. In the author's opinion, the cause is that the energy the explorers looked for was simply not there! The author's hypothesis is that a meteoroid encountered a gas pouch in the atmosphere, producing a devastating explosion, its effects being amplified by soil fluidization.

  20. Study on transient of fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Streck, E.E.

    1988-01-01

    The point kinetic equations for a Fluidized-Bed Nuclear Reactor are solved by the method of Hansen. Due to the time varying nature of the reactor volume, the equations have a non-conventional formulation (moving boundary problem), but the method of solution preserves its asymptotic convergence and efficiency characteristics under this formulation. A one dimensional and linearized thermal hydraulics feedback model was coupled to the point kinetic equations in order to obtain a more realistic representation of the reactor power. The resulting equations are solved by the Euler explicit method. (author)

  1. Product removal and solids transport from fluidized-bed calciners

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Munger, D.H.

    1978-09-01

    Methods of removing the solid product from pilot-plant and production fluidized-bed calciners, and transporting product to underground storage vaults are reported here. Testing of dense-phase solids transport systems in test loops during development of a 15-cm-diam. and 30-cm-diam. calciner are described. A lean-phase solid transport system is used with the Waste Calcining Facility. The results of some recent tests done in a lean-phase transport system connected to the 30-cm-diam. calciner are included in this report

  2. Gasification of sawdust in pressurised internally circulating fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Maartensson, R.; Lindblom, M. [Lund Univ. (Sweden). Dept. of Chemical Engineering

    1996-12-31

    A test plant for pressurised gasification of biofuels in a internally circulating fluidized bed has been built at the department of Chemical Engineering II at the University of Lund. The design performance is set to maximum 20 bar and 1 050 deg C at a thermal input of 100 kW or a maximum fuel input of 18 kg/in. The primary task is to study pressurised gasification of biofuels in relation to process requirements of the IGCC concept (integrated gasification combined cycle processes), which includes studies in different areas of hot gas clean-up in reducing atmosphere for gas turbine applications. (orig.)

  3. Classification of tungsten powder by fluidization method and its application

    International Nuclear Information System (INIS)

    Li Khan-Guan'.

    1989-01-01

    Search for accessible in practice, the technological method to increase the level of control of the granulometric composition of tungsten powder and to increase quality of products and to prepare new materials is carried out. It is shown that the method of fluidization is effective and accessible in practice for tungsten powder (and other refractory metals and compounds) classification, that increases the level of control of the granulometric composition of the powder and thus - its quality, and that improves control of properties of tungsten and other refractory metal products

  4. 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.)

  5. Self-organization and chaos in a fluidized bed

    International Nuclear Information System (INIS)

    Daw, C.S.; Finney, C.E.A.; Vasudevan, M.; van Goor, N.A.; Nguyen, K.; Bruns, D.D.; Kostelich, E.J.; Grebogi, C.; Ott, E.; Yorke, J.A.

    1995-01-01

    We present experimental evidence that a complex system of particles suspended by upward-moving gas can exhibit low-dimensional bulk behavior. Specifically, we describe large-scale collective particle motion referred to as slugging in an industrial device known as a fluidized bed. As gas flow increases from zero, the bulk motion evolves from a fixed point to periodic oscillations to oscillations intermittently punctuated by ''stutters,'' which become more frequent as the flow increases further. At the highest flow tested, the behavior becomes extremely complex (''turbulent'')

  6. Pre-germinated Parboiled Brown Rice Drying Using Fluidization Technique

    OpenAIRE

    Nattapol Poomsa-ad; Lamul Wiset

    2012-01-01

    Pre-germinated parboiled brown rice or Khao hang (in Thai) is paddy which undergoing the processes of soaking, steaming, drying and dehusking to obtain the edible form for consumption. The objectives of this research were to study the kinetic of pre-germinated parboiled brown rice drying using fluidization technique and to study the properties of pre-germinated parboiled brown rice after drying. The dryings were performed at the different temperatures of 110, 120 and 130 oC at the bed depth o...

  7. Dynamic behavior and control requirements of an atmospheric fluidized-bed coal combustion power plant: A conceptual study

    Energy Technology Data Exchange (ETDEWEB)

    Smith, O.L.

    1987-06-01

    A first-principles model of a nominal 20-MW atmospheric-pressure fluidized-bed coal combustion (AFBC) power plant was developed to provide insight into fundamental dynamic behavior of fluidized-bed systems. The control system included major loops for firing rate, steam pressure and temperature, forced and induced draft air flow, SO/sub 2/ emission, drum water level, evaporator recirculation, and bed level. The model was used to investigate system sensitivity to design features such as the distribution of heat transfer surface among the bed boiler and superheater and the out-of-bed superheater. Also calculated were the sensitivities of temperatures, pressures, and flow rates to changes in throttle, attemperator, and feedwater valve settings and forced and induced draft damper settings. The large bed mass, accounting for approx.40% of the active heat capacity, may vary under load change and could impact controller tuning. Model analysis indicated, however, that for the design studied, the change in bed mass does not appear to significantly affect controller tuning even if the bed mass varies appreciably under load-following conditions. Several bed designs are being considered for AFBC plants, some with partitions between bed sections and some without, and these differences may significantly affect the load-following capability of the plant. The results indicated that the slumping mode of operation can cause distortion of the heat source/sink distribution in the bed such that the load-following capability (rate of load change) of the plant may be reduced by as much as a factor of 5 compared with the mode in which tube surface is exposed. 9 refs., 13 figs., 6 tabs.

  8. Thermal stability in a newly designed columnar-conical fluidized bed for combustion of rice husk

    Energy Technology Data Exchange (ETDEWEB)

    Rozainee, M.; Salema, A.A.; Ngo, S.P.; Chye, G.B. [Malaysian Technological Univ., Johor Bahru (Malaysia). Dept. of Chemical Engineering

    2006-07-01

    The effects of fluidizing and liquid propane gas (LPG) flow rates on thermal stability of a fluidized bed were examined. The aim of the study was to hybridize a columnar and conical fluidized bed (CCFB) in order to encourage the combustion of low-calorific fuels such as rice husks. Experiments were conducted to examine the thermal stability of the CCFB. Premixed primary air and liquid propane gas (LPG) was fed into the bed in order to verify its thermal stability. Temperature profiles of the combustor and bed were measured. The impact of the fluidizing velocity and LPG flow rate on the temperature profile was examined in order to analyze the influence of the fluidizing velocity and LPG rate on combustion rates. Results of the study showed that the combustion of the CCFB was sustained at a fluidizing velocity of 1.5 U{sub mf} and at an LPG flow rate of 8 liters per minute. Results of the study showed that fluidizing velocity played an important role on the thermal stability of the bed. It was concluded that the thermal stability of the combustor is sufficient for the CCFB. 13 refs., 2 tabs., 5 figs.

  9. Chaotic behavior in a hydrodynamic model of a fluidized bed reactor

    International Nuclear Information System (INIS)

    Schouten, J.C.; van den Bleek, C.M.

    1991-01-01

    Recent preliminary experimental studies using time-series analysis have demonstrated that the multi-phase flow in fluidized bed reactors can be characterized as chaotic. In the present paper, it is therefore argued that the chaotic time-dependence of fluidization is a characteristic feature which should be included in scaling rules for fluidized bed reactors. For example, the similarity groups applied in dimensionless fluidized bed scaling should be improved by extending them with functions of the relevant numbers from chaos theory, such as the correlation and embedding dimension or the maximum Lyapunov exponent. This requires that the dependence of these numbers on fluidization parameters must be theoretically and experimentally investigated. The concept of chaos in fluidization also requires that the classical, empirically developed, hydrodynamic models that are applied in fluidized bed scaling are amended to include time-dependence, non-linearity as well as a sufficient level of complexity before they can predict any chaotic behavior. An example is given of chaotic behavior generated in the classical counter-current flow model according to Van Deemter by writing the upwards solids velocity as a harmonic oscillating function of time. A low-dimensional strange attractor is found, embedded in two-dimensional phase space, of which the correlation dimension depends on the solids exchange coefficient

  10. Mixing Behaviors of Wet Granular Materials in a Pulsating Fluidized Bed

    Science.gov (United States)

    Lim, Eldin Wee Chuan

    2017-11-01

    The Discrete Element Method combined with Computational Fluid Dynamics was coupled with a capillary liquid bridge force model for computational studies of mixing behaviors in a gas fluidized bed containing wet granular materials. There was a high tendency for wet particles to form large agglomerates within which relative motions between adjacent particles were hindered. This resulted in much lower mixing efficiencies compared with fluidization of dry particles. Capillary liquid bridge forces were on average stronger than both fluid drag forces and particle-particle collision forces. Particle exchange between agglomerates was necessary for mixing to occur during fluidization of wet granular materials but required strong capillary liquid bridge forces to be overcome. When pulsation of the inlet gas flow was applied, voidage waves comprising regions of high and low particle concentration formed within the fluidized bed. This allowed particles to cluster and disperse repeatedly, thus facilitating exchange of particles between agglomerates and promoting mixing of particles throughout the fluidized bed. This points towards the possibility of utilizing pulsed fluidization as an effective means of improving mixing efficiencies in fluidized bed systems containing wet granular materials.

  11. Scaling up of the fluidized bed granulation process.

    Science.gov (United States)

    Rambali, B; Baert, L; Massart, D L

    2003-02-18

    The scaling up of a fluidized bed granulation process from small scale to production scale is often done empirically in the pharmaceutical industry. In this study, a more practical and systematic method was developed in order to achieve a similar granule size in the scaled up fluid bed. The scaling up is based on the relative droplet size, and the powder bed moisture content at the end of the spraying cycle. The present study describes the scaling up of the fluidized granulation process from small (5 kg scale) to medium (30 kg scale) and to production fluid bed scale (120 kg scale). The granulation process is scaled up with as target a geometric mean granule size of 400 microm. First, the effect of the relative droplet size on the granule size was investigated in the different fluid beds. The effect of the change in relative droplet size on the granule size was different for each fluid bed. Second, experimental design is applied on the small and the medium fluid scale, and regression models for the granule size are proposed in order to scale up the granulation process on the small to medium scale. The granulation process was also successful by scaling-up to the large fluid bed, considering only the relative droplet size.

  12. Co-combustion of waste materials using fluidized bed technology

    Energy Technology Data Exchange (ETDEWEB)

    M. Lopes; I. Gulyurtlu; P. Abelha; T. Crujeira; D. Boavida; I. Cabrita [INETI-DEECA, Lisbon (Portugal)

    2004-07-01

    There is growing interest in using renewable fuels in order to sustain the CO{sub 2} accumulation. Several waste materials can be used as coal substitutes as long as they contain significant combustible matter, as for example MSW and sewage sludge. Besides the outcome of the energetic valorization of such materials, combustion must be regarded as a pre-treatment process, contributing to the safe management of wastes. Landfilling is an expensive management option and requires a previous destruction of the organic matter present in residues, since its degradation generates greenhouse gases and produces acidic organic leachates. Fluidized bed combustion is a promising technology for the use of mixtures of coal and combustible wastes. This paper presents INETI's experience in the co-combustion of coal with this kind of residues performed in a pilot fluidized bed. Both the RDF (from MSW and sewage sludge) and sewage sludge combustion problems were addressed, relating the gaseous emissions, the behaviour of metals and the leachability of ashes and a comparison was made between co-combustion and mono-combustion in order to verify the influence of the utilization of coal. 9 refs., 1 fig., 3 tabs.

  13. Microwave fluidized-bed detoxification of hazardous waste

    Energy Technology Data Exchange (ETDEWEB)

    Varma, R.

    1991-11-01

    Our ongoing research and development (R D) work focuses on demonstrating the technical feasibility of total detoxification of C1HC'' hazardous waste by using microwave energy. In addition, we investigated the capability of nahacolite for in-bed scavenging of HC1 and found it to be very effective. So far, detoxification of halocarbon vapor and liquid waste forms has been achieved. Microwave energy heats and activates the particulates of silicon carbide (SiC) and promotes chemical interactions, facilitating total detoxification of chlorinated hydrocarbons (TCEs) in an air-stream over SiC-fluidized beds under mild (<600{degrees}) conditions. The SiC promotes surface-enhanced reactions and also is a heating transfer medium. These microwave-assisted processes appear to be extremely energy efficient. The Los Alamos National Laboratory (LANL) team can demonstrate the microwave fluidized bed (MFB) technology for total detoxification of halocarbon waste streams. The technology is applicable for treatment of hazardous waste at DOE sites. 5 refs., 5 figs.

  14. On fluidization of borosilicate glasses in intense radiation fields - 16055

    International Nuclear Information System (INIS)

    Ojovan, Michael; Moebus, Guenter; Tsai, Jim; Cook, Stuart; Yang, Guang

    2009-01-01

    The viscosity is rate-limiting for many processes in glassy materials such as homogenisation and crystallisation. Changes in the viscous flow behaviour in conditions of long-term irradiation are of particular interest for glassy materials used in nuclear installations as well as for nuclear waste immobilising glasses. We analyse the viscous flow behaviour of oxide amorphous materials in conditions of electron-irradiation using the congruent bond lattice model of oxide materials accounting for the flow-mediating role of broken bonds termed configurons. An explicit equation of viscosity was obtained which is in agreement with experimental data for non-irradiated glasses and shows for irradiated glasses, first, a significant decrease of viscosity, and, second, a stepwise reduction of the activation energy of flow. An equation for glass-transition temperature was derived which shows that irradiated glasses have lower glass transition temperatures. Intensive electron irradiation of glasses causes their fluidization due to non-thermal bond breaking and can occur below the glass transition temperature. Due to surface tension forces fluidization of glasses at enough high electron flux densities can result in modification of nano-size volumes and particles such as those experimentally observed under TEM electron beams. (authors)

  15. Cold-Flow Circulating Fluidized-Bed Identification

    Energy Technology Data Exchange (ETDEWEB)

    Parviz Famouri

    2005-07-01

    In a variety of industrial applications, the use of a circulating fluidized bed (CFB) provides various advantages, such as reducing environmental pollution and increasing process efficiency. The application of circulating fluidized bed technology contributes to the improvement of gas-solid contact, reduction of the cross-sectional area with the use of higher superficial velocities, the use of the solids circulation rate as an additional control variable, and superior radial mixing, Grace et al. [1]. In order to improve raw material usage and utility consumption, optimization and control of CFB is very important, and an accurate, real time model is required to describe and quantify the process. Currently there is no accepted way to construct a reliable model for such a complex CFB system using traditional methods, especially at the pilot or industrial scale. Three major obstacles in characterizing the system are: 1) chaotic nature of the system; 2) non-linearity of the system, and 3) number of immeasurable unknowns internal to the system,[2]. Advanced control theories and methods have the ability to characterize the system, and can overcome all three of these obstacles. These methods will be discussed in this report.

  16. Fluidized bed gasification of waste-derived fuels.

    Science.gov (United States)

    Arena, Umberto; Zaccariello, Lucio; Mastellone, Maria Laura

    2010-07-01

    Five alternative waste-derived fuels obtained from municipal solid waste and different post-consumer packaging were fed in a pilot-scale bubbling fluidized bed gasifier, having a maximum feeding capacity of 100 kg/h. The experimental runs utilized beds of natural olivine, quartz sand or dolomite, fluidized by air, and were carried out under various values of equivalence ratio. The process resulted technically feasible with all the materials tested. The olivine, a neo-silicate of Fe and Mg with an olive-green colour, has proven to be a good candidate to act as a bed catalyst for tar removal during gasification of polyolefin plastic wastes. Thanks to its catalytic activity it is possible to obtain very high fractions of hydrogen in the syngas (between 20% and 30%), even using air as the gasifying agent, i.e. in the most favourable economical conditions and with the simplest plant and reactor configuration. The catalytic activity of olivine was instead reduced or completely inhibited when waste-derived fuels from municipal solid wastes and aggregates of different post-consumer plastic packagings were fed. Anyhow, these materials have given acceptable performance, yielding a syngas of sufficient quality for energy applications after an adequate downstream cleaning. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  17. 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.

  18. The multi-stage tectonic evolution of the Xitieshan terrane, North Qaidam orogen, western China : From Grenville-age orogeny to early-Paleozoic ultrahigh-pressure metamorphism

    NARCIS (Netherlands)

    Zhang, Cong; Bader, Thomas; Zhang, Lifei; van Roermund, Herman

    The geodynamic evolution of the early Paleozoic ultrahigh-pressure metamorphic belt in North Qaidam, western China, is controversial due to ambiguous interpretations concerning the nature and ages of the eclogitic protoliths. Within this framework, we present new LA-ICP-MS U-Pb zircon ages from

  19. A process to produce effervescent tablets: fluidized bed dryer melt granulation.

    Science.gov (United States)

    Yanze, F M; Duru, C; Jacob, M

    2000-11-01

    The purpose of the present study was to apply melt granulation in a fluidized bed dryer (fluidized bed dryer melt granulation) to manufacture one-step effervescent granules composed of anhydrous citric acid and sodium bicarbonate to make tablets. This study permitted us to establish that such process parameters as concentrations of polyethylene glycol (PEG) 6000, residence times in the fluidized bed dryer, fineness of PEG6000, fineness of initial mixture effervescent systems, and efficiency of two lubricants markedly affect some granule and tablet characteristics. It is a dry process that is simple, rapid, effective, economical, reproducible, and particularly adapted to produce effervescent granules that are easily compressed into effervescent tablets.

  20. A comparison of granules produced by high-shear and fluidized-bed granulation methods.

    Science.gov (United States)

    Morin, Garett; Briens, Lauren

    2014-08-01

    Placebo granules were manufactured by both wet high-shear and fluidized-bed techniques. The granules were compared based on size, shape, surface morphology, and a variety of different flowability measurements. This comparison showed that granule formation and growth were different, with induction growth for high-shear granulation and steady growth for fluidized-bed granulation. Final granules from high-shear granulation were more spherical and dense compared with the irregular granules from fluidized-bed granulation. The high-shear granules demonstrated better overall flow properties.

  1. Fluidized bed spray granulation: analysis of heat and mass transfers and dynamic particle populations

    Directory of Open Access Journals (Sweden)

    S. Heinrich

    2005-06-01

    Full Text Available A model was developed taking into consideration the heat and mass transfer processes in liquid-sprayed fluidized beds. Such fluidized beds (FB are used for granulation, coating and agglomeration. Conclusions are drawn on the relevance of particle dispersion, spraying and drying to temperature and concentrations distributions. In extension, the model was coupled with a population balance model to describe the particle size distribution and the seeds formation for continuous external FBSG (fluidized bed spray granulation with non-classifying product discharge and a screening and milling unit in the seeds recycle. The effects of seeds formation on the stability of the process is discussed.

  2. Bioreactors with Light-Beads Fluidized Bed: The Voidage Function and its Expression

    Directory of Open Access Journals (Sweden)

    Iliev Vasil

    2014-12-01

    Full Text Available Light-beads fluidized bed bioreactors with gel particles are an attractive alternative for the implementation of a system with immobilized cells. They have a number of advantages: soft operating conditions, ability to work in an ideal mixing regime, intensification of heat- and mass transfer processes in the fermentation system. The expansion characteristics of the fluidized bed were investigated in the present work. The fluidized bed expansion was described using the voidage function. It was found that the voidage can be described by nonlinear regression relationships and the regression coefficients were a function of the particles parameters.

  3. Interface pressure mapping pilot study to select surfaces that effectively redistribute pediatric occipital pressure.

    Science.gov (United States)

    Higer, Samantha; James, Thomas

    2016-02-01

    The aim of this pilot study was to better inform clinical decisions to prevent pediatric occipital pressure ulcers with quantitative data to choose an appropriate reactive support surface. A commercially available capacitive pressure mapping system (XSENSOR, X3 Medical Seat System, Calgary, Canada) was used to evaluate a standard pediatric mattress and four commercially available pressure-redistributing support surfaces. The pressure mapping system was validated for use in the pediatric population through studies on sensitivity, accuracy, creep, and repeatability. Then, a pilot pressure mapping study on healthy children under 6 years old (n = 22) was performed to determine interface pressure and pressure distribution between the occipital region of the skull and each surface: standard mattress, gel, foam, air and fluidized. The sensor was adequate to measure pressure generated by pediatric occipital loading, with 0.5-9% error in accuracy in the 25-95 mmHg range. The air surface had the lowest mean interface pressure (p pressure index (PPI), defined as the peak pressure averaged over four sensels, (p pressure for mattress, foam, fluidized, gel, and air materials were 24.8 ± 4.42, 24.1 ± 1.89, 19.4 ± 3.25, 17.9 ± 3.10, and 14.2 ± 1.41 mmHg, respectively. The air surface also had the most homogenous pressure distribution, with the highest mean to PPI ratio (p surfaces (p surface was the most effective pressure-redistributing material for pediatric occipital pressure as it had the lowest interface pressure and a homogeneous pressure distribution. This implies effective envelopment of the bony prominence of the occiput and increasing contact area to decrease peak pressure points. Copyright © 2015 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

  4. Scale-up of an electrical capacitance tomography sensor for imaging pharmaceutical fluidized beds and validation by computational fluid dynamics

    Science.gov (United States)

    Wang, Haigang; Yang, Wuqiang

    2011-10-01

    The aim of this research is to apply electrical capacitance tomography (ECT) in pharmaceutical fluidized beds and scale up the application of ECT from a lab-scale fluidized bed to a production-scale fluidized bed. The objective is to optimize the design of the production-scale fluidized bed and to improve the operation efficiency of the fluidization processes. This is the first time that ECT has been scaled up to a production-scale fluidized bed of 1.0 m diameter and batch process capacity of 100 kg in a real industrial environment. With a large-scale fluidized bed in a real industrial environment, some key issues on the ECT sensor design must be addressed. To validate ECT measurement results, a two-phase flow model has been used to simulate the process in a lab-scale and pilot-scale fluidized bed. The key process parameters include solid concentration, average concentration profiles, the frequency spectrum of signal fluctuation obtained by the fast Fourier transfer (FFT) and multi-level wavelet decomposition in the time domain. The results show different hydrodynamic behaviour of fluidized beds of different scales. The time-averaged parameters from ECT and computational fluid dynamics are compared. Future work on the ECT sensor design for large-scale fluidized beds are given in the end of the paper.

  5. Advancement of an Infra-Red Technique for Whole-Field Concentration Measurements in Fluidized Beds

    Directory of Open Access Journals (Sweden)

    Jose A. Medrano

    2016-02-01

    Full Text Available For a better understanding and description of the mass transport phenomena in dense multiphase gas-solids systems such as fluidized bed reactors, detailed and quantitative experimental data on the concentration profiles is required, which demands advanced non-invasive concentration monitoring techniques with a high spatial and temporal resolution. A novel technique based on the selective detection of a gas component in a gas mixture using infra-red properties has been further developed. The first stage development was carried out using a very small sapphire reactor and CO2 as tracer gas. Although the measuring principle was demonstrated, the real application was hindered by the small reactor dimensions related to the high costs and difficult handling of large sapphire plates. In this study, a new system has been developed, that allows working at much larger scales and yet with higher resolution. In the new system, propane is used as tracer gas and quartz as reactor material. In this study, a thorough optimization and calibration of the technique is presented which is subsequently applied for whole-field measurements with high temporal resolution. The developed technique allows the use of a relatively inexpensive configuration for the measurement of detailed concentration fields and can be applied to a large variety of important chemical engineering topics.

  6. Advancement of an Infra-Red Technique for Whole-Field Concentration Measurements in Fluidized Beds.

    Science.gov (United States)

    Medrano, Jose A; de Nooijer, Niek C A; Gallucci, Fausto; van Sint Annaland, Martin

    2016-02-27

    For a better understanding and description of the mass transport phenomena in dense multiphase gas-solids systems such as fluidized bed reactors, detailed and quantitative experimental data on the concentration profiles is required, which demands advanced non-invasive concentration monitoring techniques with a high spatial and temporal resolution. A novel technique based on the selective detection of a gas component in a gas mixture using infra-red properties has been further developed. The first stage development was carried out using a very small sapphire reactor and CO₂ as tracer gas. Although the measuring principle was demonstrated, the real application was hindered by the small reactor dimensions related to the high costs and difficult handling of large sapphire plates. In this study, a new system has been developed, that allows working at much larger scales and yet with higher resolution. In the new system, propane is used as tracer gas and quartz as reactor material. In this study, a thorough optimization and calibration of the technique is presented which is subsequently applied for whole-field measurements with high temporal resolution. The developed technique allows the use of a relatively inexpensive configuration for the measurement of detailed concentration fields and can be applied to a large variety of important chemical engineering topics.

  7. Performance of the Fluidized Bed Steam Reforming Product Under Hydraulically Unsaturated Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J.; Qafoku, Nikolla; Williams, Benjamin D.; Rod, Kenton A.; Bowden, Mark E.; Brown, Christopher F.; Pierce, Eric M.

    2014-05-01

    Currently, several candidates for secondary waste immobilization at the Hanford site in the State of Washington, USA are being considered. To demonstrate the durability of the product in the unsaturated Integrated Disposal Facility (IDF) at the site, a series of tests have been performed one of the candidate materials using the Pressurized Unsaturated Flow (PUF) system. The material that was tested was the Fluidized Bed Steam Reformer (FBSR) granular product and the granular product encapsulated in a geopolymer matrix. The FBSR product is composed primarily of an insoluble sodium aluminosilicate matrix with the dominant phases being feldspathoid minerals mostly nepheline, sodalite, and nosean. The PUF test method allows for the accelerated weathering of materials, including radioactive waste forms, under hydraulically unsaturated conditions, thus mimicking the open-flow and transport properties that most likely will be present at the IDF. The experiments show a trend of decreasing tracer release as a function of time for several of the elements released from the material including Na, Si, Al, and Cs. However, some of the elements, notably I and Re, show a steady release throughout the yearlong test. This result suggests that the release of these minerals from the sodalite cage occurs at a different rate compared with the dissolution of the predominant nepheline phase.

  8. Effect of flue gas recirculation on heat transfer in a supercritical circulating fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Błaszczuk Artur

    2015-09-01

    Full Text Available This paper focuses on assessment of the effect of flue gas recirculation (FGR on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB combustor. The performance test in supercritical CFB combustor with capacity 966 MWth was performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.

  9. Combustion en lit fluidisé Fluidized-Bed Combustion

    Directory of Open Access Journals (Sweden)

    Chrysostome G.

    2006-11-01

    Full Text Available Après quelques rappels généraux sur la fluidisation où seront présentés en par-ticulier les avantages qu'elle offre en combustion, on exposera l'état actuel du développement des générateurs à lit fluidisé opérant avec les combustibles suivants : charbon, combustibles pétroliers, résidus divers ; il sera fait mention de la contribution de l'Institut Français du Pétrole (IFP dans les deux derniers domaines.On présentera ensuite les installations les plus récentes en traitement de minerais (grillage des sulfures, calcination de calcaires. En raison de son importance on examinera encore les possibilités de désulfuration au sein de lits fluidisés, de même que seront commentés les travaux de régénération des absorbants.On terminera enfin en mentionnant les développements des lits circulants ou rapides, considérés comme les réacteurs de la seconde génération. After a general review of fluidization including in particular the advantages it offers for combustion, this article describes the present state of the development of fluidized-bed gcnerators operating with the following fuels : cool, petroleum fuels, different residues. Mention is made of Institut Français du Pétrole (IFP contribution in the last two fields. Then the most recent ore-treating installations are described (roasting of sulfides, calcination of limestones. Because of its importance, the possibilities of desulfurizoticn inside fluidized beds is examined, and research on the regeneration of absorbants is commented on. The article ends by mentioning the development of circulating or fast beds which are considered as second generation reactors.

  10. A review of oxy-fuel combustion in fluidized bed reactors

    CSIR Research Space (South Africa)

    Mathekga, HI

    2016-06-01

    Full Text Available Presently, there is no detailed review that summarizes the current knowledge status on oxy-fuel combustion in fluidized bed combustors. This paper reviewed the existing literature in heat transfer, char combustion and pollutant emissions oxy...

  11. Mathematical modeling of a fluidized bed rice husk gasifier: Part 3 -- Model verification

    Energy Technology Data Exchange (ETDEWEB)

    Mansaray, K.G.; Ghaly, A.E.; Al-Taweel, A.M.; Ugursal, V.I.; Hamdullahpur, F.

    2000-04-01

    The validity of the two-compartment model developed for fluidized bed gasification of biomass was tested using experimental data obtained from a dual-distributor-type fluidized bed gasifier. The fluidized bed was operated on rice husks at various bed heights (19.5, 25.5, and 31.5 cm), fluidization velocities (0.22, 0.28, and 0.33 m/s), and equivalence ratios (0.25, 0.30, and 0.35). The model gave reasonable predictions of the core, annulus, and exit temperatures as well as the mole fractions of the combustible gas components and product gas higher heating value, except for the overall carbon conversion, which was overestimated. This could be attributed to uncertainties in the sampling procedure.

  12. Mathematical modeling of a fluidized bed rice husk gasifier: Part 3 - Model verification

    Energy Technology Data Exchange (ETDEWEB)

    Mansaray, K.G.; Ghaly, A.E.; Al-Taweel, A.M.; Ugursal, V.I.; Hamdullahpur, F.

    2000-03-01

    The validity of the two-compartment model developed for fluidized bed gasification of biomass was tested using experimental data obtained from a dual-distributor-type fluidized bed gasifier. The fluidized bed was operated on rice husks at various bed heights (19.5, 25.5, and 31.5 cm), fluidization velocities (0.22, 0.28, and 0.33 m/s), and equivalence ratios (0.25, 0.30, and 0.35). The model gave reasonable predictions of the core, annulus, and exit temperatures as well as the mole fractions of the combustible gas components and product gas higher heating value, except for the overall carbon conversion, which was overestimated. This could be attributed to uncertainties in the sampling procedure. (Author)

  13. Operating experience and data on revolving type fluidized bed incineration plants

    International Nuclear Information System (INIS)

    Nakayama, J.

    1990-01-01

    In refuse incinerators operating by revolving fluidization (Revolving Type Fluidized Bed Incinerator) a broad range of wastes, from low caloric refuse of high moisture content to high caloric value material including a wide variety of plastics, can be incinerated at high efficiency because the unit is outstanding in terms of distribution of waste in the incinerator bed and uniformity of heat. In addition, its vigorous revolving fluidization action is very effective in pulverizing refuse, so even relatively strict emission standards can be met without fine pre-shredding. Residues are discharged in a clean, dry form free of putrescible material. Data on practical operation of the revolving fluidized bed incinerator are presented in this paper

  14. A grid-independent EMMS/bubbling drag model for bubbling and turbulent fluidization

    DEFF Research Database (Denmark)

    Luo, Hao; Lu, Bona; Zhang, Jingyuan

    2017-01-01

    The EMMS/bubbling drag model takes the effects of meso-scale structures (i.e. bubbles) into modeling of drag coefficient and thus improves coarse-grid simulation of bubbling and turbulent fluidized beds. However, its dependence on grid size has not been fully investigated. In this article, we adopt...... a periodic domain show the new drag model is less sensitive to grid size because of the additional dependence on local slip velocity. When applying the new drag model to simulations of realistic bubbling and turbulent fluidized beds, we find grid-independent results are easier to obtain for high......-velocity turbulent fluidized bed cases. The simulation results indicate that the extended EMMS/bubbling drag model is a potential method for coarse-grid simulations of large-scale fluidized beds....

  15. Computational Fluid Dynamics Simulation of Fluidized Bed Polymerization Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Rong [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are available in the open literature, such as the well-mixed model developed by McAuley, Talbot, and Harris (1994), the constant bubble size model (Choi and Ray, 1985) and the heterogeneous three phase model (Fernandes and Lona, 2002). Most these research works focus on the kinetic aspects, but from industrial viewpoint, the behavior of FB reactors should be modeled by considering the particle and fluid dynamics in the reactor. Computational fluid dynamics (CFD) is a powerful tool for understanding the effect of fluid dynamics on chemical reactor performance. For single-phase flows, CFD models for turbulent reacting flows are now well understood and routinely applied to investigate complex flows with detailed chemistry. For multiphase flows, the state-of-the-art in CFD models is changing rapidly and it is now possible to predict reasonably well the flow characteristics of gas-solid FB reactors with mono-dispersed, non-cohesive solids. This thesis is organized into seven chapters. In Chapter 2, an overview of fluidized bed polymerization reactors is given, and a simplified two-site kinetic mechanism are discussed. Some basic theories used in our work are given in detail in Chapter 3. First, the governing equations and other constitutive equations for the multi-fluid model are summarized, and the kinetic theory for describing the solid stress tensor is discussed. The detailed derivation of DQMOM for the population balance equation is given as the second section. In this section

  16. Nucla circulating atmospheric fluidized bed demonstration project. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute`s decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  17. Anaerobic degradation of linear alkylbenzene sulfonate in fluidized bed reactor

    Directory of Open Access Journals (Sweden)

    L. L. Oliveira

    2010-12-01

    Full Text Available An anaerobic fluidized bed reactor was used to assess the degradation of the surfactant linear alkylbenzene sulfonate (LAS. The reactor was inoculated with sludge from an UASB reactor treating swine wastewater and was fed with a synthetic substrate supplemented with LAS. Sand was used as support material for biomass immobilization. The reactor was kept in a controlled temperature chamber (30±1 ºC and operated with a hydraulic retention time (HRT of 18 h. The LAS concentration was gradually increased from 8.2±1.3 to 45.8±5.4 mg.L-1. The COD removal was 91%, on average, when the influent COD was 645±49 mg.L-1. The results obtained by chromatographic analysis showed that the reactor removed 93% of the LAS after 270 days of operation.

  18. Application of fluidization to separate packaging waste plastics.

    Science.gov (United States)

    Carvalho, M Teresa; Ferreira, Célia; Portela, Antía; Santos, João Tiago

    2009-03-01

    The objective of the experimental work described in this paper is the study of the separation of PS (polystyrene) from PET (polyethylene terephthalate) and PVC (polyvinyl chloride) from drop-off points using a fluidized bed separator. This is a low-cost process commonly used in the hydro-classification of mineral ores. Firstly, experimental tests were carried out with artificial granulated samples with different grain sizes, types and sources of plastic ("separability tests"). The particle settling velocities were determined under different operating conditions. Then, based on the results, the laboratory tests continued with real mixtures of waste plastics ("separation tests") and the efficiency of the process was evaluated. From a PET-rich mixture, a concentrate of PS with a 75% grade in PS was produced while the underflow was quite clear from PS (grade less than 0.5% in PS).

  19. Bubbling fluidized bed boiler for Vanaja power plant

    Energy Technology Data Exchange (ETDEWEB)

    Sormunen, R.; Haermae, P.; Vessonen, K.; Ketomaeki, A. [ed.

    1998-07-01

    At the Vanaja Power Plant, on the outskirts of Haemeenlinna, there have been changes which reflect the central goals in IVO`s product development work. At Vanaja, efficiency is combined with environmental friendliness. In the early 1980s, the plant was modernized to produce district heat in addition to electricity. At that time, along with the new gas turbine at the plant, the main fuel, coal, while remaining the fuel for the old boilers, was replaced by natural gas. This year a new type of bubbling fluidized bed boiler enabling continuous use of peat and trial use of biofuels along with coal was introduced at the plant. In addition to the Nordic countries, this kind of technology is required in central eastern Europe, where modernization of ageing power plants is being planned to achieve the best possible solutions in respect of production and the environment. IVO develops a new repair technique for underwater sites

  20. Fluidized bed incineration of a slurry waste from caprolactam production

    Energy Technology Data Exchange (ETDEWEB)

    Cammarota, A.; D' Amore, M.; Donsi, G.; Massimilla, L.

    1980-08-01

    Caprolactam tails are a slurry waste produced in the SNIA process for the synthesis of caprolactam. They contain about 65% water, 25% ash and 10% combustible matter. The ashes are low melting, due to the presence of sodium compounds. The incineration of this waste is carried out at temperatures below 600/sup 0/C in beds of silica sand, using a laboratory scale apparatus with a 40 mm ID fluidization column. Variables investigated include sand particle size, slurry flow rate, bed temperature, bed height. The concentrations of CO/sub 2/ and CO are determined continuously in the flue gases. Bed solids are sampled periodically to determine the carbon content. Results of experiments show that the low temperature incineration on a bed of inert solids is a useful technique for the disposal of caprolactam tails. 8 refs.

  1. A numerical model of a fluidized bed biomass gasifier

    Energy Technology Data Exchange (ETDEWEB)

    Hongming Jiang; Morey, R.V. (Minnesota Univ., St. Paul, MN (United States). Dept. of Agricultural Engineering)

    1992-01-01

    A one-dimensional, steady state, numerical model was developed for a fluidized bed biomass gasifier. The gasifier model consists of a fuel pyrolysis model, an oxidation model, a gasification model and a freeboard model. Given the bed temperature, ambient air flow rate and humidity ratio, fuel moisture content and reactor parameters, the model predicts the fuel feed rate for steady state operation, composition of the producer gas and fuel energy conversion. The gasifier model was validated with experimental results. The effects of major mechanisms (fuel pyrolysis and the chemical and the physical rate processes) were assessed in a sensitivity study of the gasification model. A parametric study was also conducted for the gasifier model. It is concluded that the model can be used for gasifier performance analysis. (author)

  2. Acoustic monitoring of a fluidized bed coating process

    DEFF Research Database (Denmark)

    Naelapaa, Kaisa; Veski, Peep; Pedersen, Joan G.

    2007-01-01

      The aim of the study was to investigate the potential of acoustic monitoring of a production scale fluidized bed coating process. The correlation between sensor signals and the estimated amount of film applied and percentage release, respectively, were investigated in coating potassium chloride...... (KCl) crystals with ethylcellulose (EC). Vibrations were measured with two different types of accelerometers. Different positions for placing the accelerometers and two different product containers were included in the study. Top spray coating of KCl was chosen as a ‘worst case' scenario from a coating...... point perspective. The acoustic monitoring has the potential of summarising the commonly used means to monitor the coating process. The best partial least squares (PLS) regressions, obtained by the high frequency accelerometer, showed for the release a correlation coefficient of 0.92 and a root mean...

  3. Acoustic fluidization and the scale dependence of impact crater morphology

    Science.gov (United States)

    Melosh, H. J.; Gaffney, E. S.

    1983-01-01

    A phenomenological Bingham plastic model has previously been shown to provide an adequate description of the collapse of impact craters. This paper demonstrates that the Bingham parameters may be derived from a model in which acoustic energy generated during excavation fluidizes the rock debris surrounding the crater. Experimental support for the theoretical flow law is presented. Although the Bingham yield stress cannot be computed without detailed knowledge of the initial acoustic field, the Bingham viscosity is derived from a simple argument which shows that it increases as the 3/2 power of crater diameter, consistent with observation. Crater collapse may occur in material with internal dissipation Q as low as 100, comparable to laboratory observations of dissipation in granular materials. Crater collapse thus does not require that the acoustic field be regenerated during flow.

  4. Conceptual design of a fluidized bed nuclear reactor: Statics, dynamics and safety-related aspects

    OpenAIRE

    Agung, A.

    2007-01-01

    In this thesis a conceptual design of an innovative high temperature reactor based on the fluidization principle (FLUBER) is proposed. The reactor should satisfy the following requirements: (a) modular and low power, (b)) large shutdown margin, (c) able to produce power when the bed of particles expands and stop as soon as the coolant flow is lost, (d) stable from the reactivity point of view, (e) resistant to inherent fluctuations in the fluidization regime, and (f) able to remove post-shutd...

  5. Adaptation of the continuous cold trap system of fluidized-bed to the fluoride volatility process

    International Nuclear Information System (INIS)

    1976-02-01

    A continuous cold trap system consisting of fluidized condenser and stripper has been evaluated with a view to adapt it to the Fluoride Volatility Process in establishing the continuous purification process without radiation decomposition of PuF 6 . Its feasibility is shown by the test with UF 6 -air. Necessary conditions for the cold trap, and performance of the two inch-dia. fluidized bed cold trap system are presented, and also a model of mist formation in the condenser. (auth.)

  6. An Overview of Atmospheric Fluidized Bed Combustion Systems as Applied to Army Scale Central Heat Plants

    Science.gov (United States)

    1992-11-01

    or burned in a separate fluidizcd bed combustor called a carbon burnup cell. Fuel and Sorbent Feed. To achieve high combustion efficier.cy and maximum...AFBC tecnnology is relatively new, calculating the boiler efficiency of fluidized bed boilers is not as well defined as it is for conventional boilers...paragraphs will highlight some options to improve the combustion efficiency. A carbon burnup cell (CBC) uses a separate fluidized bed operated at a much

  7. A Comparison of Granules Produced by High-Shear and Fluidized-Bed Granulation Methods

    OpenAIRE

    Morin, Garett; Briens, Lauren

    2014-01-01

    Placebo granules were manufactured by both wet high-shear and fluidized-bed techniques. The granules were compared based on size, shape, surface morphology, and a variety of different flowability measurements. This comparison showed that granule formation and growth were different, with induction growth for high-shear granulation and steady growth for fluidized-bed granulation. Final granules from high-shear granulation were more spherical and dense compared with the irregular granules from f...

  8. Fluidized beds with interal screens. II. Study in a cylindrical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jodra, L.G.; Aragon, J.M.; Corella, J.

    1979-10-01

    A fluidized bed reactor with several horizontal tube screens was studied. The number of tubes in a row, the number of rows, and the height to the bottom of the screen were varied. The conversion increase for the chemical reaction of butanol and ammonia was used as a criterion to develop several correlations between screen efficiency and the above variables. The application of the results for the design of fluidized beds with internal screens is also given.

  9. OPTIMIZATION OF DESIGN PARAMETERS OF A STIRLING GENERATOR FOR USE WITH A FLUIDIZED BED COMBUSTOR

    OpenAIRE

    Lombardi, Simone; Bizon, Katarzyna; Marra, Francesco; Continillo, Gaetano

    2012-01-01

    This work investigates the possibility to place the head of a Stirling engine, more specifically the elements of the hot side heat exchanger, in direct contact with the sand of a Fluidized Bed Combustor. This choice is primarily suggested by the heat exchange coefficients between the multiphase fluidized bed medium and the surface of the heat exchanger, much larger than those attained when the heat exchanger is located in the stream of hot flue gases. Moreover, the mechanical action exerted b...

  10. Review of the phenomenon of fluidization and its numerical modelling techniques

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-10-01

    Full Text Available The paper introduces the phenomenon of fluidization as a process. Fluidization occurs when a fluid (liquid or gas is pushed upwards through a bed of granular material. This may make the granular material to behave like a liquid and, for example, keep a level meniscus on a tilted container, or make a lighter object float on top and a heavier object sink to the bottom. The behavior of the granular material, when fluidized, depends on the superficial gas velocity, particle size, particle density, and fluid properties resulting in various regimes of fluidization. These regimes are discussed in detail in the paper. This paper also discusses the application of fluidized beds from its early usage in the Winkler coal gasifier to more recent applications for manufacturing of carbon nano-tubes. In addition, Geldart grouping based on the range of particle sizes is discussed. The minimum fluidization condition is defined and it is demonstrated that it may be registered slightly different when particles are being fluidized or de-fluidized. The paper presents discussion on three numerical modelling techniques: the two fluid model, unresolved fluid-particle model and resolved fluid particle model. The two fluid model is often referred to Eulerian-Eulerian method of solution and assumes particles as well as fluid as continuum. The unresolved and resolved fluid-particle models are based on Eulerian-Lagrangian method of solution. The key difference between them is the whether to use a drag correlation or solve the boundary layer around the particles. The paper ends with the discussion on the applicability of these models.

  11. A multi-stage-flash desalination plant of relative small performance with an integrated pressurized water reactor as a nuclear heat source

    International Nuclear Information System (INIS)

    Peltzer, M.; Petersen, G.

    1976-01-01

    In the Krupp-GKSS joint study MINIPLEX the requirements for seawater-desalination-plants with a performance in the range of 10,000 to 80,000 m 3 /d heated by a nuclear reactor are investigated. The reactor concept is similar to the integrated pressurized water reactor (IPWR) of the nuclear ship OTTO HAHN. The calculated costs of the desalinated water show, that due to the fuel cost advantages of reactors small and medium nuclear desalination plants are economically competetive with oil-fired plants since the steep rise of oil price in autumn 1973. (orig.) [de

  12. Sludge combustion in fluidized bed reactors at laboratory scale

    International Nuclear Information System (INIS)

    Chirone, R.; Cammarota, A.

    2001-01-01

    The combustion of a dried sewage sludge in laboratory scale fluidized bed has been studied in Naples by the Istituto di ricerche sulla combustione (Irc) in the framework of a National project named Thermal Process with Energy Recovery to be used in laboratory and pre-pilot scale apparatus. The attention has been focused on emissions of unreacted carbon as elutriated fines, on the emissions of pollutant gases and on the assessment of the inventory of fly- and bottom ashes. The combustion behaviour of sewage sludge has been compared with those of a market available Tyre Derived Fuel (TDF) and a biomass from Mediterranean area (Robinia Pseudoacacia) and with that of a South African bituminous coal. Stationary combustion tests were carried out at 850 0 C by feeding particles in the size range 0-1 mm into a bed of silica sand without any sorbent addition. The fluidized bed combustor has been operated, at a superficial gas velocity of 0.4 m/s and different excesses of air ranging between 14 and 98%. Relatively high combustion efficiency, larger than 98.9% has been obtained in experiments carried out with sewage sludge and excess of air larger than 20%. These values, are comparable with those obtained in previously experimental activity carried out under similar operative conditions with a South Africa Bituminous coal (97-98%). It is larger than those obtained by using a Tyre Derived Fuel (89-90%) and the Robinia Pseudoacacia Biomass (93-93%). The relative importance of carbon fines elutriation, CO emissions and volatile bypassing the bed in determining the loss of combustion efficiency has been evaluated for the different fuels tested [it

  13. Environmental remediation with products of fluidized bed combustion

    International Nuclear Information System (INIS)

    Kim, A.G.

    1999-01-01

    Commercialization of fluidized bed combustion (FBC) technology could be enhanced by increased utilization of FBC products (ash). In the US, coal combustion products (CCP) are not hazardous under RCRA and are regulated as residual waste by the states. The composition of CCP from fluidized beds is primarily determined by the inorganic constituents in coal, the sorbent reaction products and the unreacted sorbent. The combustion system and the inclusion of other fuels may also affect the chemical composition, physical properties and leaching behavior. The alkalinity of the FBC material, residual lime and pozzolanic properties are desirable characteristics for use in soil stabilization and mine reclamation. At reclaimed surface coal mines, placement of CCP is intended to reduce the amount of acid mine drainage (AMD) produced at such sites. Neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion are believed to be the mechanisms facilitated by the alkaline material. Comparison of water quality, before and after injection of a grout composed of FBC ash and water indicated small increases in pH and decreases in acidity at discharge points. The concentrations of calcium and magnesium in water samples generally increased compared to background levels. The average concentration of trace elements (arsenic, cobalt, copper, nickel and zinc) was slightly elevated in the injection areas, but in down dip and discharge water samples were comparable to background levels. Over a four year period, the average acidity in the injected area decreased by approximately 30%, a value similar to another site where a mixture of class F fly ash and cement was injected. Although coal mine remediation is a beneficial environmental use of FBC products, its effectiveness may be related to the amount of FBCB used and the method of emplacement

  14. From continuum analytical description to discrete numerical modelling of localized fluidization in granular media

    Directory of Open Access Journals (Sweden)

    Puig i Montellà Eduard

    2017-01-01

    Full Text Available We present analytical and numerical results on localized fluidization within a granular layer subjected to a local injection of fluid. As the injection rate increases the three different regimes previously reported in the literature are recovered: homogeneous expansion of the bed, fluidized cavity in which fluidization starts developing above the injection area, and finally the chimney of fluidized grains when the fluidization zone reaches the free surface. The analytical approach is at the continuum scale, based on Darcy’s law and Therzaghi’s effective stress principle. It provides a good description of the phenomenon as long as the porosity of the granular assembly remains relatively homogeneous. The numerical approach is at the particle scale based on the coupled DEM-PFV method. It tackles the more heterogeneous situations which occur at larger injection rates. A direct link is evidenced between the occurrence of the different regimes of fluidization and the injection aperture. Finally, the merging of chimneys in case of two injection points is investigated.

  15. An experimental study of fluidization behavior using flow visualization and image processing

    International Nuclear Information System (INIS)

    Laan, Flavio T. van der; Sefidvash, Farhang; Cornelius, Vanderli

    2000-01-01

    A program of experimental study of fluidization of heavy spherical pellets with water using image processing technique has been started in the Nuclear Engineering Department of the Federal University of Rio Grande do Sul. Fluidization for application in nuclear reactors requires very detailed knowledge of its behavior as the reactivity is closely dependent on the porosity of the fluidized bed. A small modular nuclear reactor concept with suspended core is under study. A modified version of the reactor involves the choice of is to make conical the shape of the reactor core to produce a non-fluctuating bed and consequently guarantee the dynamic stability of the reactor. A 5 mm diameter steel ball are fluidized with water in a conical Plexiglass tube. A pump circulate the water in a loop feeding the room temperature water from the tank into the fluidization system and returning it back to the tank. A controllable valve controls the flow velocity. A high velocity digital CCD camera captures the images of the pellets moving in the fluidized tube. At different flow velocities, the individual pellets can be tracked by processing the sequential frames. A DVT digital tape record stores the images and by acquisition through interface board into a microcomputer. A special program process the data later on. Different algorithm of image treatment determines the velocity fields of the pellets. The behavior of the pellets under different flow velocity and porosity are carefully studied. (author)

  16. Lignite air-steam gasification in the fluidized bed of iron-containing slag catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, B.N.; Shchipko, M.L.; Golovin, Yu. [Inst. of Chemistry of Natural Organic Materials, Academgorodok, Krasnoyarsk (Russian Federation)

    1995-12-01

    The influence of fluidized bed of iron-containing slag particles on air-steam gasification of powdered Kansk-Achinsk lignite in entrained flow was studied in pilot installation with productivity about 60 kg per hour. Slag of Martin process and boiler slag were used as catalytic active materials until their complete mechanical attrition. Two following methods of catalytic gasification of lignite were compared: the partial gasification in stationary fluidized bed of slag particles with degree of fuel conversion 40-70% and complete gasification in circulating bed of slag particles. In the first case only the most reactive part of fuel is gasified with the simultaneously formation of porous carbon residue with good sorption ability. It was found the catalytic fluidized bed improves heat transfer from combustion to reduction zone of gas-generator and increases the rate of fuel conversion at the temperature range 900-1000{degrees}C. At these temperatures the degree of conversion is depended considerably on the duration time of fuel particles in the catalytic fluidized bed. The influence of catalytic fluidized bed height and velocity of reaction mixture on the temperature profiles in the gas-generator was studied. The optimal relationship was found between the fluidized bed height and velocity of flow which makes possible to produce the gas with higher calorific value at maximum degree of fuel conversion.

  17. Effect of compaction history on the fluidization behavior of fine cohesive powders

    Science.gov (United States)

    Valverde, Jose Manuel; Castellanos, Antonio

    2006-05-01

    Fine particles agglomerate in the fluidized state due to the strength of interparticle attractive forces as compared to particle weight. Interparticle adhesion can be largely increased by consolidation stresses applied during powder handling. As a consequence, fragments of the consolidated powder may persist when the powder is fluidized, which gives rise to large agglomerates of strongly adhered particles in fluidization. This history-dependent effect can be minimized by coating the particles with surface additives such as silica nanoparticles. In this paper, we investigate the effect of high consolidation stresses σc previously applied to samples of silica-coated fine particles on their fluidization behavior. Our experimental measurements show that, even though homogeneous fluidization is still observed, the average agglomerate size and fractal dimension of the agglomerates increase as σc is increased. Bed expansion in the fluidized state is hindered by previously applied high consolidations, which we attribute to an increase of the largest stable size of mesoscopic fluid pockets. As a consequence, we observe that the initiation of macroscopic bubbling is delayed up to larger values of the fluid velocity.

  18. A new method of analysis of standing foot pressure images for detection of the plantar ulcers in early-stage diabetic neuropathy.

    Science.gov (United States)

    Gopalakrishna Prabhu, K; Mothiram Patil, K; Srinivasan, S

    2001-01-01

    In this paper, studies are performed on a large number of diabetic patients belonging to different levels of plantar sensation loss, by analyzing the standing foot pressure images in the frequency domain. A new parameter, the power ratio (PR, the ratio of high frequency power to the total power in an image), is used to distinguish between foot pressure image patterns of diabetic neuropathic subjects (at different levels of sensation loss) and those of normal feet. The foot areas of the diabetic subjects are scanned in 10 specified areas using Semmes Weinstein's nylon monofilaments to quantify the diabetic neuropathy. A statistical study of the mean values of this parameter in different plantar areas of the feet for different levels of diabetic neuropathy indicates distinguishing trends. The result could help in the early detection of low-level sensation loss by establishing the threshold of the PR in a particular area above which there could be the possibility of plantar ulcer formation. This information could be utilized by orthopedic surgeons to devise early corrective methods to protect the feet from further damage due to plantar ulcers.

  19. Demonstration of a Full-Scale Fluidized Bed Bioreactor for the Treatment of Perchlorate at Low Concentrations in Groundwater

    Science.gov (United States)

    2009-01-01

    Fluidized Bed Reactor Iron Granulated Activated Carbon Gallons per minute Health & Safety Plan Hydraulic Residence Time Investigation-Derived Waste...FINAL REPORT Demonstration of a Full-Scale Fluidized Bed Bioreactor for the Treatment of Perchlorate at Low Concentrations in Groundwater...area code) 20-01-2009 Final Report March 2006-March 2008; January 2009 DEMONSTRATION OF A FULL-SCALE FLUIDIZED BED BIOREACTOR FOR THE TREATMENT OF

  20. Development of a fluidized bed agglomeration modeling methodology to include particle-level heterogeneities in ash chemistry and granular physics

    Science.gov (United States)

    Khadilkar, Aditi B.

    The utility of fluidized bed reactors for combustion and gasification can be enhanced if operational issues such as agglomeration are mitigated. The monetary and efficiency losses could be avoided through a mechanistic understanding of the agglomeration process and prediction of operational conditions that promote agglomeration. Pilot-scale experimentation prior to operation for each specific condition can be cumbersome and expensive. So the development of a mathematical model would aid predictions. With this motivation, the study comprised of the following model development stages- 1) development of an agglomeration modeling methodology based on binary particle collisions, 2) study of heterogeneities in ash chemical composition and gaseous atmosphere, 3) computation of a distribution of particle collision frequencies based on granular physics for a poly-disperse particle size distribution, 4) combining the ash chemistry and granular physics inputs to obtain agglomerate growth probabilities and 5) validation of the modeling methodology. The modeling methodology comprised of testing every binary particle collision in the system for sticking, based on the extent of dissipation of the particles' kinetic energy through viscous dissipation by slag-liquid (molten ash) covering the particles. In the modeling methodology developed in this study, thermodynamic equilibrium calculations are used to estimate the amount of slag-liquid in the system, and the changes in particle collision frequencies are accounted for by continuously tracking the number density of the various particle sizes. In this study, the heterogeneities in chemical composition of fuel ash were studied by separating the bulk fuel into particle classes that are rich in specific minerals. FactSage simulations were performed on two bituminous coals and an anthracite to understand the effect of particle-level heterogeneities on agglomeration. The mineral matter behavior of these constituent classes was studied

  1. Heat transfer characteristics in a pulsated fluidized bed in relation to bubble characteristics; Parusu ryudoso no dennetsu tokusei to kiho tokusei tono sokan

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, A.; Hasatani, M. [Nagoya Univ., Nagoya (Japan). Dept. of Energy Engineering and Science; Deguchi, S. [Nagoya Univ., Nagoya (Japan). Center for Integrated Research inn Science and Engineering; Matsuda, H. [Nagoya Univ., Nagoya (Japan). Research Center for Advanced Waste and Emission Management; Mujumdar, A.S. [McGill Univ., Quebec (Canada). Dept. of Chemical Engineering

    2000-11-10

    A pulsated fluidized bed is operated with two sequential duration designated as the on-period with injecting fluidization air, and the off-period without injecting fluidization air. The heat transfer coefficient between a vertically immersed heater and bed in a pulsated fluidized bed is measured under various pulse cycles and fluidized particles. The obtained results are compared with those in a normal fluidized bed with continuous fluidization air injection. The relation between heat transfer coefficient and bubble characteristics, evaluated by using a digital video camera, was investigated. For certain fluidized particles and operated pulse cycles, fluidization of particles and increment of heat transfer coefficient can be obtained under lower mean air velocity based on a pulse cycle duration than minimum fluidization air velocity of the normal fluidized bed. Under the pulse cycles where a static ed is formed in off-period duration, the improved heat transfer rate in contrast with the normal fluidized bed can be measured. This because of the large bubbles formation. As the heat transfer in the pulsated fluidized bed is obstructed with increasing time to keep a static bed due to the excess of-period duration it is indicated that there is an optimum off-period duration based on the heat transfer rate. (author)

  2. Preparation of Fine Particles with Improved Solubility Using a Complex Fluidized-Bed Granulator Equipped with a Particle-Sizing Mechanism.

    Science.gov (United States)

    Hosaka, Shouichi; Okamura, Yasufumi; Tokunaga, Yuji

    2016-01-01

    A new type of fluidized-bed granulator equipped with a particle-sizing mechanism was used for the preparation of fine particles that improved the solubility of a poorly water-soluble drug substance. Cefteram pivoxyl (CEF) was selected as a model drug substance, and its solution with a hydrophilic polymer, hydroxypropyl cellulose (HPC-L), was sprayed on granulation grade lactose monohydrate (Lac). Three types of treated particles were prepared under different conditions focused on the spraying air pressure and the amount of HPC-L. When the amount of HPC-L was changed, the size of the obtained particles was similar. However, particle size distribution was dependent on the amount of HPC-L. Its distribution became more homogenous with greater amounts of HPC-L, but the particle size distribution obtained by decreasing the spraying air pressure was not acceptable. By processing CEF with HPC-L using a complex fluidized-bed granulator equipped with a particle-sizing mechanism, the dissolution ratio was elevated by approximately 40% compared to that of unprocessed CEF. Moreover, in the dissolution profile of treated CEF, the initial burst was suppressed, and nearly zero order release was observed up to approximately 60% in the dissolution profile. This technique may represent a method with which to design fine particles of approximately 100 µm in size with a narrow distribution, which can improve the solubility of a drug substance with low solubility.

  3. Sorption-enhanced steam methane reforming in fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Kim

    2006-10-15

    Hydrogen is considered to be an important potential energy carrier; however, its advantages are unlikely to be realized unless efficient means can be found to produce it without generation of CO{sub 2}. Sorption-enhanced steam methane reforming (SE-SMR) represent a novel, energy-efficient hydrogen production route with in situ CO{sub 2} capture, shifting the reforming and water gas shift reactions beyond their conventional thermodynamic limits. The use of fluidized bed reactors for SE-SMR has been investigated. Arctic dolomite, a calcium-based natural sorbent, was chosen as the primary CO{sub 2}-acceptor in this study due to high absorption capacity, relatively high reaction rate and low cost. An experimental investigation was conducted in a bubbling fluidized bed reactor of diameter 0.1 m, which was operated cyclically and batch wise, alternating between reforming/carbonation conditions and higher-temperature calcination conditions. Hydrogen concentrations of >98 mole% on a dry basis were reached at 600 C and 1 atm, for superficial gas velocities in the range of {approx}0.03-0.1 m/s. Multiple reforming-regeneration cycles showed that the hydrogen concentration remained at {approx}98 mole% after four cycles. The total production time was reduced with an increasing number of cycles due to loss of CO{sub 2}-uptake capacity of the dolomite, but the reaction rates of steam reforming and carbonation seemed to be unaffected for the conditions investigated. A modified shrinking core model was applied for deriving carbonation kinetics of Arctic dolomite, using experimental data from a novel thermo gravimetric reactor. An apparent activation energy of 32.6 kj/mole was found from parameter fitting, which is in good agreement with previous reported results. The derived rate expression was able to predict experimental conversion up to {approx}30% very well, whereas the prediction of higher conversion levels was poorer. However, the residence time of sorbent in a continuous

  4. The Effect of Air Preheat at Atmospheric Pressure on the Formation of NO(x) in the Quick-Mix Sections of an Axially Staged Combustor

    Science.gov (United States)

    Vardakas, M. A.; Leong, M. Y.; Brouwer, J.; Samuelsen, G. S.; Holdeman, J. D.

    1999-01-01

    The Rich-burn/Quick-mix/Lean-burn (RQL) combustor concept has been proposed to minimize the formation of nitrogen oxides (NO(x)) in gas turbine systems. The success of this combustor strategy is dependent upon the efficiency of the mixing section bridging the fuel-rich and fuel-lean stages. Note that although these results were obtained from an experiment designed to study an RQL mixer, the link between mixing and NOx signatures is considerably broader than this application, in that the need to understand this link exists in most advanced combustors. The experiment reported herein was designed to study the effects of inlet air temperature on NO(x) formation in a mixing section. The results indicate that NO(x) emission is increased for all preheated cases compared to non-preheated cases. When comparing the various mixing modules, the affect of jet penetration is important, as this determines where NO(x) concentrations peak, and affects overall NO(x) production. Although jet air comprises 70 percent of the total airflow, the impact that jet air preheat has on overall NO(x) emissions is small compared to preheating both main and jet air flow.

  5. Evaluation of browning ratio in an image analysis of apple slices at different stages of instant controlled pressure drop-assisted hot-air drying (AD-DIC).

    Science.gov (United States)

    Gao, Kun; Zhou, Linyan; Bi, Jinfeng; Yi, Jianyong; Wu, Xinye; Zhou, Mo; Wang, Xueyuan; Liu, Xuan

    2017-06-01

    Computer vision-based image analysis systems are widely used in food processing to evaluate quality changes. They are able to objectively measure the surface colour of various products since, providing some obvious advantages with their objectivity and quantitative capabilities. In this study, a computer vision-based image analysis system was used to investigate the colour changes of apple slices dried by instant controlled pressure drop-assisted hot air drying (AD-DIC). The CIE L* value and polyphenol oxidase activity in apple slices decreased during the entire drying process, whereas other colour indexes, including CIE a*, b*, ΔE and C* values, increased. The browning ratio calculated by image analysis increased during the drying process, and a sharp increment was observed for the DIC process. The change in 5-hydroxymethylfurfural (5-HMF) and fluorescent compounds (FIC) showed the same trend with browning ratio due to Maillard reaction. Moreover, the concentrations of 5-HMF and FIC both had a good quadratic correlation (R 2  > 0.998) with the browning ratio. Browning ratio was a reliable indicator of 5-HMF and FIC changes in apple slices during drying. The image analysis system could be used to monitor colour changes, 5-HMF and FIC in dehydrated apple slices during the AD-DIC process. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  6. Experimental investigation of thermal conductivity coefficient and heat exchange between fluidized bed and inclined exchange surface

    Directory of Open Access Journals (Sweden)

    B. Stojanovic

    2009-06-01

    Full Text Available The paper presents experimental research of thermal conductivity coefficients of the siliceous sand bed fluidized by air and an experimental investigation of the particle size influence on the heat transfer coefficient between fluidized bed and inclined exchange surfaces. The measurements were performed for the specific fluidization velocity and sand particle diameters d p=0.3, 0.5, 0.9 mm. The industrial use of fluidized beds has been increasing rapidly in the past 20 years owing to their useful characteristics. One of the outstanding characteristics of a fluidized bed is that it tends to maintain a uniform temperature even with nonuniform heat release. On the basis of experimental research, the influence of the process's operational parameters on the obtained values of the bed's thermal conductivity has been analyzed. The results show direct dependence of thermal conductivity on the intensity of mixing, the degree of fluidization, and the size of particles. In the axial direction, the coefficients that have been treated have values a whole order higher than in the radial direction. Comparison of experimental research results with experimental results of other authors shows good agreement and the same tendency of thermal conductivity change. It is well known in the literature that the value of the heat transfer coefficient is the highest in the horizontal and the smallest in the vertical position of the heat exchange surface. Variation of heat transfer, depending on inclination angle is not examined in detail. The difference between the values of the relative heat transfer coefficient between vertical and horizontal heater position for all particle sizes reduces by approximately 15% with the increase of fluidization rate.

  7. Numerical simulation of the unsteady and turbulent flow in a high-pressure turbine stage; Simulation numerique de l'ecoulement instationnaire et turbulent dans un etage de turbine haute pression

    Energy Technology Data Exchange (ETDEWEB)

    Bastin, G.

    2004-09-15

    The aim of this study concerns the use of numerical methods for the resolution of the Reynolds Averaged Navier Stokes equations adapted to the simulation of the cooling of the trailing edge of a stator in a high pressure turbine. These methods, based on the elsA solver developed at ONERA, use a four steps Runge Kutta time discretization scheme and a Jameson centered space discretization scheme. The scheme is applied through a finite volume approach on control volume centered on the cells of a multi-block structured mesh. Turbulence is simulated either through the algebraic Michel model, or through the one-transport-equation Spalart-Allmaras model, or through the two-transport-equations k 1, k {omega} and k {epsilon} models, and through ASM model. A simulation of the flow in a bidimensional stator, without cooling, is carried out. The cooling, which is realized with trailing edge slots, is then simulated on a bidimensional stator. Because the slot is represented by meshes overlapping the mesh of the smooth blade, the Chimera method is chosen. This method makes it possible computations with overlapping meshes. The comparison with the experimental data, on these two first computations has validated this strategy to represent such slots. The tridimensional simulation of a single stator with taking account of the cooling is then realized. It showed the complex and tridimensional aspects of the main flow with focus on the influence of the cooling system. Finally two steady computations, without and with cooling, and an unsteady computation without cooling are carried out on a high pressure turbine stage. The comparison with the experimental data obtained in the frame of the European Brite-Euram program is made. These results make it possible to determine the effect of the cooling on the flow in a turbine stage. (authors)

  8. Advanced Magnetic Materials Methods and Numerical Models for Fluidization in Microgravity and Hypogravity

    Science.gov (United States)

    Atwater, James; Wheeler, Richard, Jr.; Akse, James; Jovanovic, Goran; Reed, Brian

    2013-01-01

    To support long-duration manned missions in space such as a permanent lunar base, Mars transit, or Mars Surface Mission, improved methods for the treatment of solid wastes, particularly methods that recover valuable resources, are needed. The ability to operate under microgravity and hypogravity conditions is essential to meet this objective. The utilization of magnetic forces to manipulate granular magnetic media has provided the means to treat solid wastes under variable gravity conditions by filtration using a consolidated magnetic media bed followed by thermal processing of the solid wastes in a fluidized bed reactor. Non-uniform magnetic fields will produce a magnetic field gradient in a bed of magnetically susceptible media toward the distributor plate of a fluidized bed reactor. A correctly oriented magnetic field gradient will generate a downward direct force on magnetic media that can substitute for gravitational force in microgravity, or which may augment low levels of gravity, such as on the Moon or Mars. This approach is termed Gradient Magnetically Assisted Fluidization (G-MAFB), in which the magnitude of the force on the fluidized media depends upon the intensity of the magnetic field (H), the intensity of the field gradient (dH/dz), and the magnetic susceptibility of the media. Fluidized beds based on the G-MAFB process can operate in any gravitational environment by tuning the magnetic field appropriately. Magnetic materials and methods have been developed that enable G-MAFB operation under variable gravity conditions.

  9. [Thermal energy utilization analysis and energy conservation measures of fluidized bed dryer].

    Science.gov (United States)

    Xing, Liming; Zhao, Zhengsheng

    2012-07-01

    To propose measures for enhancing thermal energy utilization by analyzing drying process and operation principle of fluidized bed dryers,in order to guide optimization and upgrade of fluidized bed drying equipment. Through a systematic analysis on drying process and operation principle of fluidized beds,the energy conservation law was adopted to calculate thermal energy of dryers. The thermal energy of fluidized bed dryers is mainly used to make up for thermal consumption of water evaporation (Qw), hot air from outlet equipment (Qe), thermal consumption for heating and drying wet materials (Qm) and heat dissipation to surroundings through hot air pipelines and cyclone separators. Effective measures and major approaches to enhance thermal energy utilization of fluidized bed dryers were to reduce exhaust gas out by the loss of heat Qe, recycle dryer export air quantity of heat, preserve heat for dry towers, hot air pipes and cyclone separators, dehumidify clean air in inlets and reasonably control drying time and air temperature. Such technical parameters such air supply rate, air inlet temperature and humidity, material temperature and outlet temperature and humidity are set and controlled to effectively save energy during the drying process and reduce the production cost.

  10. Flow characteristics in a large jetting fluidized bed with two nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Q.; Liu, Z.; Zhang, J.

    2000-03-01

    Jetting fluidized beds are widely used in a number of industrial processes because of various advantages, such as high rates of heat and mass transfer and chemical reaction. These processes include catalytic and flame processes, combustion and gasification of coal, treatment of wastes, cleaning of dusty gases, coating, and granulation. The penetration depth for millet (1.64 mm) as fluidization particles (Geldart group D) was determined in a large jetting fluidized bed of 0.5 m inner diameter and 8 m height and with two nozzles is precorded by a video camera and analyzed frame by frame. Based on experimental data, an empirical correlation for the penetration depth is proposed. Experimental results indicate that the penetration depth increases with an increase in the jetting velocity. Under the same jet gas velocity, the penetration depth decreases as the nozzle distance decreases. Meanwhile, a simple correlation for jet coalescence height is found. A radial voidage profile in the jetting fluidized bed is investigated using a PC-4 fiber optic concentration probe, the effects of jet gas velocity, and the distance between two nozzles on the radial voidage distribution, and a radial profile with unequal jet gas velocity in a jetting fluidized bed is studied.

  11. Biological reduction of nitrates in wastewaters from nuclear processing using a fluidized-bed bioreactor

    International Nuclear Information System (INIS)

    Pitt, W.W.; Hancher, C.W.; Patton, B.D.

    1981-01-01

    There are a number of nitrate-containing wastewater sources, as concentrated as 30 wt.% NO 3 - and as large as 2000 m 3 /day, in the nuclear fuel cycle. The biological reduction of nitrate in wastewater to gaseous nitrogen, accompanied by the oxidation of a nutrient carbon source to gaseous carbon dioxide, is an ecologically sound and cost-effective method of treating wastewaters containing nitrates. These nitrate-containing wastewater sources can be successfully biologically denitrified to meet discharge standards in the range of 10 to 20 gN(NO 3 - )/m 3 by the use of a fluidized-bed bioreactor. The denitrification bacteria are a mixed culture derived from garden soil; the major strain is Pseudomonas. In the fluidized-bed bioreactor the bacteria are allowed to attach to 0.25- to 0.50-mm-diam coal fluidization particles, which are then fluidized by the upward flow of influent wastewater. Maintaining the bacteria-to-coal weight ratio at approximately 1:10 results in a bioreactor bacteria loading of greater than 20,000 g/m 3 . This paper describes the results of a biodenitrification R and D program based on the use of fluidized bioreactors capable of operating at nitrate levels up to 7000 g/m 3 and achieving denitrification rates as high as 80 g N(NO 3 - ) per day per liter of empty bioreactor volume. 4 figures, 7 tables

  12. Strategies for the startup of methanogenic inverse fluidized-bed reactors using colonized particles.

    Science.gov (United States)

    Alvarado-Lassman, A; Sandoval-Ramos, A; Flores-Altamirano, M G; Vallejo-Cantú, N A; Méndez-Contreras, J M

    2010-05-01

    One of the inconveniences in the startup of methanogenic inverse fluidized-bed reactors (IFBRs) is the long period required for biofilm formation and stabilization of the system. Previous researchers have preferred to start up in batch mode to shorten stabilization times. Much less work has been done with continuous-mode startup for the IFBR configuration of reactors. In this study, we prepared two IFBRs with similar characteristics to compare startup times for batch- and continuous-operation modes. The reactors were inoculated with a small quantity of colonized particles and run for a period of 3 months, to establish the optimal startup strategy using synthetic media as a substrate (glucose as a source of carbon). After the startup stage, the continuous- and batch-mode reactors removed more than 80% of the chemical oxygen demand (COD) in 51 and 60 days of operation, respectively; however, at the end of the experiments, the continuous-mode reactor had more biomass attached to the support media than the batch-mode reactor. Both reactors developed fully covered support media, but only the continuous-mode reactor had methane yields close to the theoretical value that is typical of stable reactors. Then, a combined startup strategy was proposed, with industrial wastewater as the substrate, using a sequence of batch cycles followed by continuous operation, which allows stable operation at an organic loading rate of 20 g COD/L x d in 15 days. Using a fraction of colonized support as an inoculum presents advantages, with respect to previously reported strategies.

  13. Fast Pyrolysis of Agricultural Wastes in a Fluidized Bed Reactor

    Science.gov (United States)

    Wang, X. H.; Chen, H. P.; Yang, H. P.; Dai, X. M.; Zhang, S. H.

    Solid biomass can be converted into liquid fuel through fast pyrolysis, which is convenient to be stored and transported with potential to be used as a fossil oil substitute. In China, agricultural wastes are the main biomass materials, whose pyrolysis process has not been researched adequately compared to forestry wastes. As the representative agricultural wastes in China, peanut shell and maize stalk were involved in this paper and pine wood sawdust was considered for comparing the different pyrolysis behaviors of agricultural wastes and forestry wastes. Fast pyrolysis experiments were carried out in a bench-scale fluidized-bed reactor. The bio-oil yieldsof peanut shell and maize stalk were obviously lower than that ofpine sawdust. Compared with pine sawdust, the char yields of peanut shell and maize stalk were higher but the heating value of uncondensable gaswas lower. This means that the bio-oil cost will be higher for agricultural wastes if taking the conventional pyrolysis technique. And the characteristic and component analysis resultsof bio-oil revealed that the quality of bio-oil from agricultural wastes, especially maize stalk, was worse than that from pine wood. Therefore, it is important to take some methods to improve the quality of bio-oilfrom agricultural wastes, which should promote the exploitation of Chinese biomass resources through fast pyrolysis in afluidized bed reactor.

  14. Research into Biomass and Waste Gasification in Atmospheric Fluidized Bed

    Energy Technology Data Exchange (ETDEWEB)

    Skala, Zdenek; Ochrana, Ladislav; Lisy, Martin; Balas, Marek; Kohout, Premysl; Skoblja, Sergej

    2007-07-01

    Considerable attention is paid in the Czech Republic to renewable energy sources. The largest potential, out of them all, have biomass and waste. The aim therefore is to use them in CHP in smaller units (up to 5MWel). These are the subject of the research summarized in our article. The paper presents results of experimental research into gasification in a 100 kW AFB gasifier situated in Energy Institute, Faculty of Mechanical Engineering, Brno University of Technology, and fitted with gas cleaning equipment. Within the research, study was carried out into gas cleaning taking primary measures in the fluidized bed and using hot filter, metal-based catalytic filter, and wet scrubber. Descriptions and diagrams are given of the gasifier and new ways of cleaning. Results include: Impact of various fuels (farming and forest wastes and fast-growing woods and culm plants) on fuel gas quality. Individual kinds of biomass have very different thermal and physical properties; Efficiency of a variety of cleaning methods on content of dust and tars and comparison of these methods; and, Impact of gasifier process parameters on resultant gas quality. (auth)

  15. Operation of a fluidized-bed bioreactor for denitrification

    International Nuclear Information System (INIS)

    Hancher, C.W.; Taylor, P.A.; Napier, J.M.

    1978-01-01

    Two denitrification fluidized-bed bioreactors of the same length (i.e., 5 m) but with different inside diameters (i.e., 5 and 10 cm) have been operated on feed ranging in nitrate concentration from 200 to 2000 g/m 3 ; thus far, good agreement has been obtained. Two 10-cm-ID bioreactors operating in series have also been tested; the results are in accordance with predicted results based on the performance of a 5-cm-ID bioreactor. The overall denitrification rate in the dual 10-cm-ID bioreactor system was found to be 23 kg N(NO 3 - )/day-m 3 using feed with a nitrate concentration of 1800 g/m 3 . Data obtained in operating-temperature tests indicate that the maximum denitrification rate is achieved between 22 and 30 0 C. These data will form the basis of the design of our mobile pilot plant which consists of dual 20-cm-ID by 7.3-m-long bioreactors

  16. Attempts on cardoon gasification in two different circulating fluidized beds

    Directory of Open Access Journals (Sweden)

    Chr. Christodoulou

    2014-11-01

    Full Text Available Few tests have been carried out in order to evaluate the use of cardoon in gasification and combustion applications most of the researchers dealt with agglomeration problems. The aim of this work is to deal with the agglomeration problem and to present a solution for the utilization of this biofuel at a near industrial application scale. For this reason, two experiments were conducted, one in TU Delft and one in Centre for Research and Technology Hellas (CERTH, using fuel cardoon and 50% w/w cardoon blended with 50% w/w giant reed respectively. Both experimental campaigns were carried out in similar atmospheric circulating fluidized bed gasifiers. Apart from the feedstock, the other differences were the gasification medium and the bed material used in each trial. The oxidizing agent at TUD׳s run was O2/steam, whereas CERTH׳s tests used air. When experiments with the cardoon 50% w/w–giant reed 50% w/w blend were performed no agglomeration problems were presented. Consequently, gasification could be achieved in higher temperature than that of pure cardoon which led to the reduction of tar concentration.

  17. Sulfide oxidation in fluidized bed bioreactor using nylon support material.

    Science.gov (United States)

    Midha, Varsha; Jha, M K; Dey, Apurba

    2012-01-01

    A continuous fluidized bed bioreactor (FBBR) with nylon support particles was used to treat synthetic sulfide wastewater at different hydraulic retention time of 25, 50 and 75 min and upflow velocity of 14, 17 and 20 m/hr. The effects of upflow velocity, hydraulic retention time and reactor operation time on sulfide oxidation rate were studied using statistical model. Mixed culture obtained from the activated sludge, taken from tannery effluent treatment plant, was used as a source for microorganisms. The diameter and density of the nylon particles were 2-3 mm and 1140 kg/m3, respectively. Experiments were carried out in the reactor at a temperature of (30 +/- 2) degrees C, at a fixed bed height of 16 cm after the formation of biofilm on the surface of support particles. Biofilm thickness reached (42 +/- 3) microm after 15 days from reactor start-up. The sulfide oxidation, sulfate and sulfur formation is examined at all hydraulic retention times and upflow velocities. The results indicated that almost 90%-92% sulfide oxidation was achieved at all hydraulic retention times. Statistical model could explain 94% of the variability and analysis of variance showed that upflow velocity and hydraulic retention time slightly affected the sulfide oxidation rate. The highest sulfide oxidation of 92% with 70% sulfur was obtained at hydraulic retention time of 75 min and upflow velocity of 14 m/hr.

  18. Heavy metal characterization of circulating fluidized bed derived biomass ash.

    Science.gov (United States)

    Li, Lianming; Yu, Chunjiang; Bai, Jisong; Wang, Qinhui; Luo, Zhongyang

    2012-09-30

    Although the direct combustion of biomass for energy that applies circulating fluidized bed (CFB) technology is steadily expanding worldwide, only few studies have conducted an environmental assessment of biomass ash thus far. Therefore, this study aims to integrate information on the environmental effects of biomass ash. We investigated the concentration of heavy metal in biomass ash samples (bottom ash, cyclone ash, and filter ash) derived from a CFB boiler that combusted agricultural and forest residues at a biomass power plant (2×12 MW) in China. Ash samples were gathered for the digestion and leaching test. The heavy metal content in the solution and the leachate was studied via an inductively coupled plasma-mass spectrometer and a Malvern Mastersizer 2000 mercury analyzer. Measurements for the chemical composition, particle size distribution, and the surface morphology were carried out. Most of the metals in cyclone ash particles were enriched, whereas Ti and Hg were enriched in filter ash. Residence time contributed most to heavy metal enrichment. Under HJ/T 300 conditions, the heavy metals showed serious leaching characteristics. Under EN 12457-2 conditions, leaching behavior was hardly detected. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Combustion test of refuse derived fuel in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Guilin; Aono, Shegeru; Yamazaki, Ryohei; Fujima, Yukihisa; Mori, Shigekatsu [Nagoya University, Aichi (Japan); Kondo, Motohiro; Yamaguchi, Masataka [Toyota Motor Corp., Aichi (Japan)

    1999-08-01

    Power generation from Refuse Derived Fuel (RFD) is a promising utilization technology for municipal municipal solid waste. To explain the combustion behaviors of RDF was fed continuously in to a 0.3 x 0.3 m x 2.73 m in height bubbling-type fluidized bed combustor and CO, NO{sub x}, SO{sub x} and HCl concentrations in the flue gas from the combustor were detected by a continuos measurement system. It is found that CO concentration in the flue gas is greatly increased by increasing the RFD feed rate, and CO concentration in the flue gas is greatly decreased by increasing the air ratio because the volatile matters rate is extremely great in combustion of RFD. It is also significantly affected by the secondary air injection and the air distribution ratio from the distributor. HCl concentration in the flue gas is effectively controlled by the calcium compound contained in RDF.HCl concentration is maintained to be less than 60 ppm when the bed temperature is 800 degree C, and the HCl removal ratio by the calcium component is higher than 70% even though under the higher bed temperature than 900 degree C. NO{sub x} concentration was among 50-150 ppm and SO{sub x} concentration is less than 0.5 ppm. (author)

  20. Development of a membrane-assisted fluidized bed reactor - 2 - Experimental demonstration and modeling for the partial oxidation of methanol

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.; Laverman, J.A.; van Sint Annaland, M.; Kuipers, J.A.M.

    2005-01-01

    A small laboratory-scale membrane-assisted fluidized bed reactor (MAFBR) was constructed in order to experimentally demonstrate the reactor concept for the partial oxidation of methanol to formaldehyde. Methanol conversion and product selectivities were measured at various overall fluidization

  1. Comparison of fibre optical measurements and discrete element simulations for the study of granulation in a spout fluidized bed

    NARCIS (Netherlands)

    Link, J.M.; Godlieb, W.; Tripp, P.; Deen, N.G.; Heinrich, S.; Kuipers, J.A.M.; Schönherr, M.; Peglow, M.

    2009-01-01

    Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties,

  2. Comparison of fibre optical measurements and discrete element simulations for the study of granulation in a spout fluidized bed

    NARCIS (Netherlands)

    Link, J.M.; Godlieb, W.; Tripp, P.; Deen, N.G.; Heinrich, S.; Peglow, M.; Kumar, J.; Kuipers, J.A.M.; Schönherr, M.; Mörl, L.

    2007-01-01

    Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties,

  3. Comparison of Fibre Optical Measurements and Discrete Element Simulations for the Study of Granulation in a Spout Fluidized Bed

    NARCIS (Netherlands)

    Link, J.M.; Godlieb, W.; Tripp, P.; Deen, N.G.; Heinrich, S.; Kuipers, J.A.M.; Schönherr, M.; Peglow, M.

    2007-01-01

    Spout fluidized beds are frequently used for the production of granules or particles through granulation. The products find application in a large variety of applications, for example detergents, fertilizers, pharmaceuticals and food. Spout fluidized beds have a number of advantageous properties,

  4. Role of microbial accumulation in biological sulphate reduction using lactate as electron donor in an inversed fluidized bed bioreactor

    NARCIS (Netherlands)

    Cassidy, J.; Frunzo, L.; Lubberding, H.J.; Villa-Gomez, D.K.; Esposito, G.; Keesman, K.J.; Lens, P.N.L.

    2017-01-01

    This study evaluated the impact of substrate accumulation (sulphate and polyhydroxybutyrate (PHB)) on bioprocess control of a sulfate reducing inversed fluidized bed bioreactor. To investigate the impact of substrate accumulation, step feed changes were induced to an inversed fluidized bed

  5. Trading stages

    DEFF Research Database (Denmark)

    Steiner, Uli; Tuljapurkar, Shripad; Coulson, Tim

    2012-01-01

    because they are hard to use and interpret, and tools for age and stage structured populations are missing. We present easily interpretable expressions for the sensitivities and elasticities of life expectancy to vital rates in age-stage models, and illustrate their application with two biological......Interest in stage-and age structured models has recently increased because they can describe quantitative traits such as size that are left out of age-only demography. Available methods for the analysis of effects of vital rates on lifespan in stage-structured models have not been widely applied...... examples. Much of our approach relies on trading of time and mortality risk in one stage for time and risk in others. Our approach contributes to the new framework of the study of age- and stage-structured biodemography....

  6. Non-catalytic pyrolysis of scrap tires using a newly developed two-stage pyrolyzer for the production of a pyrolysis oil with a low sulfur content

    International Nuclear Information System (INIS)

    Choi, Gyung-Goo; Oh, Seung-Jin; Kim, Joo-Sik

    2016-01-01

    Highlights: • Scrap tire rubber was successfully pyrolyzed in a two-stage pyrolyzer. • The two-stage pyrolyzer is composed of auger and fluidized bed reactors. • N 2 and temperatures of ∼500 °C were effective for a low-sulfur oil. • A pyrolysis oil contained only 0.55 wt.% of sulfur and 0.28 wt.% of nitrogen. • A pyrolysis oil from the auger reactor contained 50 wt.% DL-limonene. - Abstract: The aim of this work was to reduce the sulfur content of pyrolysis oil derived from the scrap tire pyrolysis. In this respect, a series of pyrolysis experiments was conducted in both a fluidized bed reactor (one-stage pyrolysis) and a newly developed two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor in series (two-stage pyrolysis). The one-stage pyrolysis was carried out at ∼500 and 600 °C with different fluidizing gases (N 2 and product gas). In the experiments, the pyrolysis oil obtained at ∼500 °C had a lower sulfur content than that produced at ∼600 °C. N 2 was better at producing a low-sulfur pyrolysis oil than product gas. The sulfur contents of the oils obtained from the one-stage pyrolysis ranged from 0.75 to 0.92 wt.%. The two-stage pyrolysis was conducted using product gas as the fluidizing medium at different auger reactor temperatures (∼230–450 °C) and at a constant fluidized bed reactor temperature (∼510 °C). A pyrolysis oil containing only 0.55 wt.% of sulfur could be produced at the temperatures of the auger reactor of ∼330 °C and fluidized bed reactor of ∼510 °C. Moreover, the two-stage pyrolysis could produce an oil with a low nitrogen content (0.28 wt.%). A pyrolysis oil obtained from the auger reactor contained DL-limonene up to 50 wt.%.

  7. Study of process parameters for reducing ammonium uranyl carbonate to uranium dioxide in fluidized bed furnace

    International Nuclear Information System (INIS)

    Leitao Junior, C.B.

    1992-01-01

    This work consists of studying the process parameters of AUC (ammonium uranyl carbonate) to U O 2 (uranium dioxide) reduction, with good physical and chemical characteristics, in fluidized bed. Initially, it was performed U O 2 cold fluidization experiments with an acrylic column. Afterward, it was done AUC to U O 2 reduction experiments, in which the process parameters influence in the granulometry, specific surface area, porosity and fluoride amount on the U O 2 powder produced were studied. As a last step, it was done compacting and sintering tests of U O 2 pellets in order to appreciate the U O 2 powder performance, obtained by fluidized bed, in the fuel pellets fabrication. (author)

  8. Bioavailability of sulfadiazine in rabbits using tablets prepared by direct compression and fluidized-bed granulation.

    Science.gov (United States)

    Ritschel, W A; Erni, W

    1977-10-01

    Experimental sulfadiazine tablets prepared by direct compression, using a commercially available direct compression tablet mass, were compared with experimental sulfadiazine tablets prepared by fluidized-bed granulation and commercially available sulfadiazine tablets USP. The values for friability and the time required to release 10 and 50% of the direct compression tablets were between those of the fluidized-bed tablets and the commercial product. With the commercial tablet as a standard, the extent of bioavailability was determined in rabbits; it was slightly higher for both the direct compression and fluidized-bed tablets. A statistically significant difference was found between the direct compression tablets and the standard with respect to the extent of bioavailability and the time of the peak.

  9. ESTABLISHMENT OF AN ENVIRONMENTAL CONTROL TECHNOLOGY LABORATORY WITH A CIRCULATING FLUIDIZED-BED COMBUSTION SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Wei-Ping Pan; Andy Wu; John T. Riley

    2004-10-30

    This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period July 1, 2004 through September 30, 2004. The following tasks have been completed. First, renovation of the new Combustion Laboratory and the construction of the Circulating Fluidized-Bed (CFB) Combustor Building have started. Second, the design if the component parts of the CFBC system have been reviewed and finalized so that the drawings may be released to the manufacturers during the next quarter. Third, the experiments for solid waste (chicken litter) incineration have been conducted using a Thermogravimetric Analyzer (TGA). This is in preparation for testing in the simulated fluidized-bed combustor. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter has been outlined in this report.

  10. Autocorrelation spectra of an air-fluidized granular system measured by NMR

    Science.gov (United States)

    Lasic, S.; Stepisnik, J.; Mohoric, A.; Sersa, I.; Planinsic, G.

    2006-09-01

    A novel insight into the dynamics of a fluidized granular system is given by a nuclear magnetic resonance method that yields the spin-echo attenuation proportional to the spectrum of the grain positional fluctuation. Measurements of the air-fluidized oil-filled spheres and mustard seeds at different degrees of fluidization and grain volume fractions provide the velocity autocorrelation that differs from the commonly anticipated exponential Enskog decay. An empiric formula, which corresponds to the model of grain caging at collisions with adjacent beads, fits well to the experimental data. Its parameters are the characteristic collision time, the free path between collisions and the cage-breaking rate or the diffusion-like constant, which decreases with increasing grain volume fraction. Mean-squared displacements calculated from the correlation spectrum clearly show transitions from ballistic, through sub-diffusion and into diffusion regimes of grain motion.

  11. Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Ryosuke [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Umekawa, Hisashi [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)], E-mail: umekawa@kansai-uac.jp; Ozawa, Mamoru [Department of Mechanical Engineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-06-21

    Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

  12. Co-combustion of risk husk with coal in a fluidized bed

    International Nuclear Information System (INIS)

    Ghani, A.K.; Alias, A.B.; Savory, R.M.; Cliffe, K.R.

    2006-01-01

    Power generation from biomass is an attractive technology which utilizes agricultural residue waste. In order to explain the behavior of biomass-fired fluidized bed incinerator, biomass sources from agricultural residues (rice husk) was co-fired with coal in a 0.15 m diameter and 2.3 m high fluidized bed combustor. The combustion efficiency and CO emissions were studied and compared with those for pure coal combustion. Biomass waste with up to 70% mass fraction can be co-combusted in a fluidized bed combustor designed for coal combustion with a maximum drop of efficiency of 20% depending upon excess air levels. CO levels fluctuated between 200-700 ppm were observed when coal is added. It is evident from this research that efficient co-firing of rice husk with coal can be achieved with minimum modification of existing coal-fired boilers. (Author)

  13. Capacitor model to interpret the electric behavior of fluidized beds. Influence of apparatus geometry

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, V.; Guardiola, J.; Vian, A.

    1986-01-01

    This work provides a model to know the degree of electrification in fluidized beds on the basis of voltage measurements between an electric probe and a metallic distributor. The model is based on the similarity of behavior between the probe-bed-distributor system and a capacitor. The influence of three variables related to apparatus geometry - height of probe, column diameter and height of bed - has been studied in an air fluidized bed of glass beads. The results show that the degree of bed electrification is not influenced by the column diameter; the effect of bed height depends on the quality of fluidization: with a bubbling bed the degree of electrification increases with bed height whereas the opposite effect is observed with a slugging bed. Additional fixed bed experiments make clear that the rate of charge dissipation grows for increasing values of bed height and column diameter, and for decreasing values of probe height.

  14. Heat transfer and flow characteristics around a finned-tube bank heat exchanger in fluidized bed

    International Nuclear Information System (INIS)

    Honda, Ryosuke; Umekawa, Hisashi; Ozawa, Mamoru

    2009-01-01

    Principal heat transfer mechanisms in a fluidized bed have been classified into three categories, i.e. solid convection, gas convection and radiation. Among these mechanisms, the solid convection is a dominant mechanism in the bubbling fluidized bed. This solid convection is substantially caused by the bubble movement, thus the visualization of the void fraction distribution becomes a very useful method to understand the characteristics of the fluidized-bed heat exchanger. In this study, the heat transfer coefficient and the void fraction around the heat transfer tube with annuler fin were measured. For the quantitative measurement of the void fraction, neutron radiography and image processing technique were employed. Owing to the existence of the annuler fin, the restriction of the particle movements was put. This restriction suppressed the disturbance caused by tubes, and the influence of the tube arrangement on the flow and heat transfer characteristics could be clearly expressed.

  15. Defluidization in fluidized bed gasifiers using high-alkali content fuels

    DEFF Research Database (Denmark)

    Narayan, Vikas; Jensen, Peter Arendt; Henriksen, Ulrik Birk

    2016-01-01

    samples,agglomeration could be attributed to viscous silicate melts formed from reaction of inorganic alkalineand alkali earth species with silica from the bed particles. A mathematical model that addresses the defluidization behavior of alkali-rich samples was developed based on the experiments performed...... and calcium, which may form viscous melts that adhere on the surface of the colliding bed particles and bind them to form agglomerates. In this paper, studies were made to understand the behavior of inorganic elements (mainly K, Si and Ca) on agglomeration and de-fluidization of alkali rich bed...... in the bench-scale fluidized bed reactor as well as on results from literature. The model was then used topredict the de-fluidization behavior of alkali-rich bed material in a large-scale LTCFB gasifier....

  16. An alternative method for float-sink analysis of fine coal samples using water fluidization

    Energy Technology Data Exchange (ETDEWEB)

    A.M. Callen; S.J. Pratten; B.D. Belcher; N. Lambert; K.P. Galvin [University of Newcastle, Callaghan, NSW (Australia). School of Engineering

    2002-12-01

    The study reported is concerned with the development of a new method, based on water fluidization, for obtaining washability information for -4 +0.045 mm coal samples, with a view to providing a rapid, accurate, and safe alternative to the current laboratory method of float-sink testing. Previously, Galvin and Pratten have reported the technique of utilizing the density segregation effect of a narrow size range of particles in a fluidized bed to determine washability data. Here, the evaluation of the new method by determining the yield-ash data of a number of different Australian coals has demonstrated the robustness and accuracy of the water fluidization method. 7 refs., 9 figs., 1 app.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  18. Construction of a quality index for granules produced by fluidized bed technology and application of the correspondence analysis as a discriminant procedure.

    Science.gov (United States)

    Albuquerque, Teresa; Dias, Vitor H; Poellinger, Norbert; Pinto, João F

    2010-08-01

    The production of granules by wet granulation in a fluidized bed was assessed after the construction of a quality index based on a file of attributes (relevant factors). These attributes are combined by a methodology relying on Correspondence Analysis, as a discriminant procedure, using two extreme simulated active vectors representing, respectively, the best and the worst cases for the granules quality output ("bad" and "good" pole). From those, a single continuous synthetic variable - the quality index - can be produced referring to a more significant set of samples. As an application of the methodology, the work compares the quality of granules produced at a laboratory scale and a pilot scale. The factors contribution to the bad or good pole allowed the identification of the most relevant factors that affect the quality of the granules. The factors studied, according to a center of gravity design, included formulation (solubility of a drug, different grades of polyvinylpyrrolidone, the polarity of the granulation solution) and processing factors (the rate of administration of the granulation solution, the atomizing air pressure and the fluidizing air rate). Granules were evaluated for production yield, drug content, size, densities (true, bulk and tapped), friability, flowability and compressibility. The study has emphasized the differences between the laboratory and pilot scales and the relative importance of each factor for the quality of the granules produced.

  19. Technical notes for the conceptual design for an atmospheric fluidized-bed direct combustion power generating plant. [Comparison of AFB plant and pulverized coal plant

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-04-01

    The first part of this report presents a comparison of the conceptual designs of a large (570 MW(e)) pulverized coal (PC) steam generator equipped with a wet limestone flue gas desulfurization (FGD) system and two equivalent sized atmospheric fluidized bed (AFB) steam generators including balance of plants for electric-power generation. The reader is cautioned that this portion of the report compares a zero generation AFB technology to pulverized coal technology which has been operationally and economically optimized for the past half-century. This comparison is intended to be indicative of whether further development of the AFB concept as a viable alternative to the PC/FGD concept for electric-power generation is merited. In the second part, the load-following capability of a once-through subcritical atmospheric fluidized bed boiler is analyzed. Digital computer simulation predictions of the plant's response to open loop step changes in firing rate, feedwater flow, governor valve, unit load demand, etc, are made. The predicted response of throttle pressure, steam temperature, unit load, etc, are compared to the response of a conventional coal-fired, once-through, subcritical unit. The load-following capability is assessed through this qualitative comparison. Additional model response predictions are also presented for which no test data are presently available.

  20. Pressurized fluidized-bed hydroretorting of Eastern oil shales -- Sulfur control

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, M.J.; Abbasian, J.; Akin, C.; Lau, F.S.; Maka, A.; Mensinger, M.C.; Punwani, D.V.; Rue, D.M. (Institute of Gas Technology, Chicago, IL (United States)); Gidaspow, D.; Gupta, R.; Wasan, D.T. (Illinois Inst. of Tech., Chicago, IL (United States)); Pfister, R.M.: Krieger, E.J. (Ohio State Univ., Columbus, OH (United States))

    1992-05-01

    This topical report on Sulfur Control'' presents the results of work conducted by the Institute of Gas Technology (IGT), the Illinois Institute of Technology (IIT), and the Ohio State University (OSU) to develop three novel approaches for desulfurization that have shown good potential with coal and could be cost-effective for oil shales. These are (1) In-Bed Sulfur Capture using different sorbents (IGT), (2) Electrostatic Desulfurization (IIT), and (3) Microbial Desulfurization and Denitrification (OSU and IGT). The objective of the task on In-Bed Sulfur Capture was to determine the effectiveness of different sorbents (that is, limestone, calcined limestone, dolomite, and siderite) for capturing sulfur (as H{sub 2}S) in the reactor during hydroretorting. The objective of the task on Electrostatic Desulfurization was to determine the operating conditions necessary to achieve a high degree of sulfur removal and kerogen recovery in IIT's electrostatic separator. The objectives of the task on Microbial Desulfurization and Denitrification were to (1) isolate microbial cultures and evaluate their ability to desulfurize and denitrify shale, (2) conduct laboratory-scale batch and continuous tests to improve and enhance microbial removal of these components, and (3) determine the effects of processing parameters, such as shale slurry concentration, solids settling characteristics, agitation rate, and pH on the process.