WorldWideScience

Sample records for thermal packed-bed reactor

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Experimental measurement of effective thermal conductivity of packed lithium-titanate pebble bed

    International Nuclear Information System (INIS)

    Mandal, D.; Sathiyamoorthy, D.; Vinjamur, M.

    2012-01-01

    Lithium titanate is a promising solid breeder material for the fusion reactor blanket. Packed lithium titanate pebble bed is considered for the blanket. The thermal energy; that will be produced in the bed during breeding and the radiated heat from the reactor core absorbed must be removed. So, the experimental thermal property data are important for the blanket design. In past, a significant amount of works were conducted to determine the effective thermal conductivity of packed solid breeder pebble bed, in helium atmosphere, but no flow of gas was considered. With increase in gas flow rate, effective thermal conductivity of pebble bed increases. Particle size and void fraction also affect the thermal properties of the bed significantly. An experimental facility with external heat source was designed and installed. Experiments were carried out with lithium-titanate pebbles of different sizes at variable gas flow rates and at different bed wall temperature. It was observed that effective thermal conductivity of pebble bed is a function of particle Reynolds number and temperature. From the experimental data two correlations have been developed to estimate the effective thermal conductivity of packed lithium-titanate pebble bed for different particle Reynolds number and at different temperatures. The experimental details and results are discussed in this paper.

  3. Hydrodynamics of multi-phase packed bed micro-reactors

    NARCIS (Netherlands)

    Márquez Luzardo, N.M.

    2010-01-01

    Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the

  4. Thermal-hydraulic modeling of porous bed reactors

    International Nuclear Information System (INIS)

    Araj, K.J.; Nourbakhsh, H.P.

    1987-01-01

    Optimum design of nuclear reactor core requires an iterative approach between the thermal-hydraulic, neutronic and operational analysis. This paper concentrates on the thermal-hydraulic behavior of a hydrogen cooled, small particle bed reactor (PBR). The PBR core, modeled here, consists of a hexagonal array of fuel elements embedded in a moderator matrix. The fuel elements are annular packed beds of fuel particles held between two porous cylindrical frits. These particles, 500 to 600 μm in diameter, have a uranium carbide core, which is coated by two layers of graphite and an outer coating of zirconium carbide. Coolant flow, radially inward, from the cold frit through the packed bed and hot frit and axially out the channel, formed by the hot frit, to a common plenum. 5 refs., 1 fig., 2 tabs

  5. Thermal-hydraulic modeling of porous bed reactors

    International Nuclear Information System (INIS)

    Araj, K.J.; Nourbakhsh, H.P.

    1987-01-01

    Optimum design of nuclear reactor cores requires an iterative approach between the thermal-hydraulic, neutronic, and operational analysis. This paper will concentrate on the thermal-hydraulic behavior of a hydrogen-cooled small particle bed reactor (PBR). The PBR core modeled here consists of a hexagonal array of fuel elements embedded in a moderator matrix. The fuel elements are annular packed beds of fuel particles held between two porous cylindrical frits. These particles, 500 to 600 μm in diameter, have a uranium carbide core, which is coated by two layers of graphite and an outer coating of zirconium carbide. Coolant flows, radially inward, from the cold frit through the packed bed and hot frit and axially out the channel, formed by the hot frit to a common plenum. A fast running one-dimensional lumped-parameter steady-state code (FTHP) was developed to evaluate the effects of design changes in fuel assembly and power distribution. Another objective for the code was to investigate various methods of coolant control to minimize hot channel effects and maximize outlet temperatures

  6. Comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, F.; van Sint Annaland, M.; Kuipers, J.A.M.

    2009-01-01

    In this work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, have been compared for the reforming of methane for the production of ultra-pure hydrogen. Using detailed theoretical models, the required membrane area to reach a given

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

    NARCIS (Netherlands)

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

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

  8. Theoretical comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, F.; van Sint Annaland, M.; Kuipers, J.A.M.

    2010-01-01

    In this theoretical work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, has been compared for ultra-pure hydrogen production via methane reforming. Using detailed theoretical models, the required membrane area to reach a given conversion

  9. Thermal-hydraulic and characteristic models for packed debris beds

    International Nuclear Information System (INIS)

    Mueller, G.E.; Sozer, A.

    1986-12-01

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

  10. Operation of Packed-Bed Reactors Studied in Microgravity

    Science.gov (United States)

    Motil, Brian J.; Balakotaiah, Vemuri

    2004-01-01

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

  11. Packed Bed Reactor Technology for Chemical-Looping Combustion

    NARCIS (Netherlands)

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

    2007-01-01

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

  12. The Performance of Structured Packings in Trickle-Bed Reactors

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped

  13. Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

    International Nuclear Information System (INIS)

    Hu Jian; Jiang Nan; Li Jie; Shang Kefeng; Lu Na; Wu Yan; Mizuno Akira

    2016-01-01

    The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. (paper)

  14. Experimental studies on the coolability of packed beds. Flooding of hot dry packed beds

    International Nuclear Information System (INIS)

    Leininger, S.; Kulenovic, R.; Laurien, E.

    2013-01-01

    In case of a severe accident in a nuclear power plant meltdown of the reactor core can occur and form a packed bed in the lower plenum of the reactor pressure vessel (RPV) after solidification due to contact with water. The removal of after-heat and the long-term coolability is of essential interest. The efficient injection of cooling water into the packed bed has to be assured without endangering the structural integrity of the reactor pressure vessel. The experiments performed aimed to study the dry-out and the quenching (flooding) of hot dry packed beds. Two different inflow variants, bottom- and top-flooding including the variation of the starting temperature of the packed bed and the injection rate were studied. In case of bottom flooding the quenching time increases with increasing packed bed temperature and decreasing injection rate. In case of top flooding the flow pattern is more complex, in a first phase the water flows preferentially toward the RPV wall, the flow paths conduct the water downwards. The flow resistance of the packed bed increases with increasing bed temperatures. The quenching temperatures increase significantly above average.

  15. Using atomic layer deposited tungsten to increase thermal conductivity of a packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Van Norman, Staci A.; Falconer, John L.; Weimer, Alan W., E-mail: alan.weimer@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado, UCB 596, Boulder, Colorado 80309-0596 (United States); Tringe, Joseph W.; Sain, John D. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550 (United States); Yang, Ronggui [Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, Colorado 80309-0427 (United States)

    2015-04-13

    This study investigated the effective thermal conductivity (k{sub eff}) of packed-beds that contained porous particles with nanoscale tungsten (W) films of different thicknesses formed by atomic layer deposition (ALD). A continuous film on the particles is vital towards increasing k{sub eff} of the packed beds. For example, the k{sub eff} of an alumina packed bed was increased by three times after an ∼8-nm continuous W film with 20 cycles of W ALD, whereas k{sub eff} was decreased on a polymer packed bed with discontinuous, evenly dispersed W-islands due to nanoparticle scattering of phonons. For catalysts, understanding the thermal properties of these packed beds is essential for developing thermally conductive supports as alternatives to structured supports.

  16. Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

    Science.gov (United States)

    Hu, Jian; Jiang, Nan; Li, Jie; Shang, Kefeng; Lu, Na; Wu, Yan; Mizuno, Akira

    2016-03-01

    The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. supported by National Natural Science Foundation of China (No. 51177007), the Joint Funds of National Natural Science Foundation of China (No. U1462105), and Dalian University of Technology Fundamental Research Fund of China (No. DUT15RC(3)030)

  17. Characteristics of convective heat transport in a packed pebble-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmohsin, Rahman S., E-mail: rsar62@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Al-Dahhan, Muthanna H., E-mail: aldahhanm@mst.edu [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 400 West 11th Street/231 Schrenk Hall, Rolla, MO 65409-1230 (United States); Department of Nuclear Engineering, 301 W. 14th St./222 Fulton Hall (United States)

    2015-04-01

    Highlights: • A fast-response heat transfer probe has been developed and used in this work. • Heat transport has been quantified in terms of local heat transfer coefficients. • The method of the electrically heated single sphere in packing has been applied. • The heat transfer coefficient increases from the center to the wall of packed bed. • This work advancing the knowledge of heat transport in the studied packed bed. - Abstract: Obtaining more precise results and a better understanding of the heat transport mechanism in the dynamic core of packed pebble-bed reactors is needed because this mechanism poses extreme challenges to the reliable design and efficient operation of these reactors. This mechanism can be quantified in terms of a solid-to-gas convective heat transfer coefficient. Therefore, in this work, the local convective heat transfer coefficients and their radial profiles were measured experimentally in a separate effect pilot-plant scale and cold-flow experimental setup of 0.3 m in diameter, using a sophisticated noninvasive heat transfer probe of spherical type. The effect of gas velocity on the heat transfer coefficient was investigated over a wide range of Reynolds numbers of practical importance. The experimental investigations of this work include various radial locations along the height of the bed. It was found that an increase in coolant gas flow velocity causes an increase in the heat transfer coefficient and that effect of the gas flow rate varies from laminar to turbulent flow regimes at all radial positions of the studied packed pebble-bed reactor. The results show that the local heat transfer coefficient increases from the bed center to the wall due to the change in the bed structure, and hence, in the flow pattern of the coolant gas. The findings clearly indicate that one value of an overall heat transfer coefficient cannot represent the local heat transfer coefficients within the bed; therefore, correlations are needed to

  18. Oxidation of ethene in a wall-cooled packed-bed reactor

    NARCIS (Netherlands)

    Schouten, E.P.S.; Borman, P.C.; Westerterp, K.R.

    1994-01-01

    The selective oxidation of ethene over a silver on α-alumina catalyst was studied in a pilot plant with a wall-cooled tubular packed bed reactor. Gas and solid temperatures in the catalyst bed were measured at different axial and radial positions as well as concentrations at different axial

  19. Modeling a Packed Bed Reactor Utilizing the Sabatier Process

    Science.gov (United States)

    Shah, Malay G.; Meier, Anne J.; Hintze, Paul E.

    2017-01-01

    A numerical model is being developed using Python which characterizes the conversion and temperature profiles of a packed bed reactor (PBR) that utilizes the Sabatier process; the reaction produces methane and water from carbon dioxide and hydrogen. While the specific kinetics of the Sabatier reaction on the RuAl2O3 catalyst pellets are unknown, an empirical reaction rate equation1 is used for the overall reaction. As this reaction is highly exothermic, proper thermal control is of the utmost importance to ensure maximum conversion and to avoid reactor runaway. It is therefore necessary to determine what wall temperature profile will ensure safe and efficient operation of the reactor. This wall temperature will be maintained by active thermal controls on the outer surface of the reactor. Two cylindrical PBRs are currently being tested experimentally and will be used for validation of the Python model. They are similar in design except one of them is larger and incorporates a preheat loop by feeding the reactant gas through a pipe along the center of the catalyst bed. The further complexity of adding a preheat pipe to the model to mimic the larger reactor is yet to be implemented and validated; preliminary validation is done using the smaller PBR with no reactant preheating. When mapping experimental values of the wall temperature from the smaller PBR into the Python model, a good approximation of the total conversion and temperature profile has been achieved. A separate CFD model incorporates more complex three-dimensional effects by including the solid catalyst pellets within the domain. The goal is to improve the Python model to the point where the results of other reactor geometry can be reasonably predicted relatively quickly when compared to the much more computationally expensive CFD approach. Once a reactor size is narrowed down using the Python approach, CFD will be used to generate a more thorough prediction of the reactors performance.

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

    Science.gov (United States)

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

    2018-03-01

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

  1. Accounting for porous structure in effective thermal conductivity calculations in a pebble bed reactor

    International Nuclear Information System (INIS)

    Antwerpen, W. van; Rousseau, P.G.; Toit, C.G. du

    2009-01-01

    A proper understanding of the mechanisms of heat transfer, flow and pressure drop through a packed bed of spheres is of utmost importance in the design of a high temperature pebble bed reactor. A thorough knowledge of the porous structure within the packed bed is important to any rigorous analysis of the transport phenomena, as all the heat and flow mechanisms are influenced by the porous structure. In this paper a new approach is proposed to simulate the effective thermal conductivity employing a combination of new and existing correlations for randomly packed beds. More attention is given to packing structure based on coordination number and contact angles, resulting in a more rigorous differentiation between the bulk and near-wall regions. The model accounts for solid conduction, gas conduction, contact area, surface roughness as well as radiation. (author)

  2. Experimental, kinetic and numerical modeling of hydrogen production by catalytic reforming of crude ethanol over a commercial catalyst in packed bed tubular reactor and packed bed membrane reactor

    International Nuclear Information System (INIS)

    Aboudheir, Ahmed; Akande, Abayomi; Idem, Raphael

    2006-01-01

    The demand for hydrogen energy has increased tremendously in recent years essentially because of the increase in the word energy consumption as well as recent developments in fuel cell technologies. The energy information administration has projected that world energy consumption will increase by 59% over the next two decades, from 1999 to 2020, in which the largest share is still dominated by fossil fuels (oil, natural gas and coal). Carbon dioxide (CO 2 ) emissions resulting from the combustion of these fossil fuels currently are estimated to account for three-fourth of human-caused CO 2 emissions worldwide. Greenhouse gas emission, including CO 2 , should be limited, as recommended at the Kyoto Conference, Japan, in December 1997. In this regard, hydrogen (H 2 ) has a significant future potential as an alternative fuel that can solve the problems of CO 2 emissions as well as the emissions of other air contaminants. One of the techniques to produce hydrogen is by reforming of hydrocarbons or biomass. Crude ethanol (a form of biomass, which essentially is fermentation broth) is easy to produce, is free of sulphur, has low toxicity, and is also safe to handle, transport and store. In addition, crude ethanol consists of oxygenated hydrocarbons, such as ethanol, lactic acid, glycerol, and maltose. These oxygenated hydrocarbons can be reformed completely to H 2 and CO 2 , the latter of which could be separated from H 2 by membrane technology. This provides for CO 2 capture for eventual storage or destruction. In the case of using crude ethanol, this will result in negative CO 2 , emissions. In this paper, we conducted experimental work on production of hydrogen by the catalytic reforming of crude ethanol over a commercial promoted Ni-based catalyst in a packed bed tubular reactor as well as a packed bed membrane reactor. As well, a rigorous numerical model was developed to simulate this process in both the catalytic packed bed tubular reactor and packed bed membrane

  3. Analysis of wall-packed-bed thermal interactions

    International Nuclear Information System (INIS)

    Gorbis, Z.R.; Tillack, M.S.; Tehranian, F.; Abdou, M.A.

    1995-01-01

    One of the major issues remaining for ceramic breeder blankets involves uncertainties in heat transfer and thermomechanical interactions within the breeder and multiplier regions. Particle bed forms are considered in many reactor blanket designs for both the breeder and Be multiplier. The effective thermal conductivity of beds and the wall-bed thermal conductance are still not adequately characterized, particularly under the influence of mechanical stresses. The problem is particularly serious for the wall conductance between Be and its cladding, where the uncertainty can be greater than 50%. In this work, we describe a new model for the wall-bed conductance that treats the near-wall region as a finite-width zone. The model includes an estimate of the region porosity based on the number of contact points, and the contact area for smooth surfaces. It solves the heat conduction in a near-wall unit cell. The model is verified with existing data and used to predict the range of wall conductances expected in future simulation experiments and in reactor applications. (orig.)

  4. Adiabatic Compressed Air Energy Storage with packed bed thermal energy storage

    International Nuclear Information System (INIS)

    Barbour, Edward; Mignard, Dimitri; Ding, Yulong; Li, Yongliang

    2015-01-01

    Highlights: • The paper presents a thermodynamic analysis of A-CAES using packed bed regenerators. • The packed beds are used to store the compression heat. • A numerical model is developed, validated and used to simulate system operation. • The simulated efficiencies are between 70.5% and 71.1% for continuous operation. • Heat build-up in the beds reduces continuous cycle efficiency slightly. - Abstract: The majority of articles on Adiabatic Compressed Air Energy Storage (A-CAES) so far have focussed on the use of indirect-contact heat exchangers and a thermal fluid in which to store the compression heat. While packed beds have been suggested, a detailed analysis of A-CAES with packed beds is lacking in the available literature. This paper presents such an analysis. We develop a numerical model of an A-CAES system with packed beds and validate it against analytical solutions. Our results suggest that an efficiency in excess of 70% should be achievable, which is higher than many of the previous estimates for A-CAES systems using indirect-contact heat exchangers. We carry out an exergy analysis for a single charge–storage–discharge cycle to see where the main losses are likely to transpire and we find that the main losses occur in the compressors and expanders (accounting for nearly 20% of the work input) rather than in the packed beds. The system is then simulated for continuous cycling and it is found that the build-up of leftover heat from previous cycles in the packed beds results in higher steady state temperature profiles of the packed beds. This leads to a small reduction (<0.5%) in efficiency for continuous operation

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  6. Cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors

    NARCIS (Netherlands)

    Budzaki, S.; Miljic, G.; Sundaram, S.; Tisma, M.; Hessel, V.

    2017-01-01

    A cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors using refined sunflower oil is performed in this work. A few enzymatic micro-flow reactors have so far reached a performance close to gram-scale, which might be sufficient for the pharmaceutical industry. This

  7. Calcium oxide/carbon dioxide reactivity in a packed bed reactor of a chemical heat pump for high-temperature gas reactors

    International Nuclear Information System (INIS)

    Kato, Yukitaka; Yamada, Mitsuteru; Kanie, Toshihiro; Yoshizawa, Yoshio

    2001-01-01

    The thermal performance of a chemical heat pump that uses a calcium oxide/carbon dioxide reaction system was discussed as a heat storage system for utilizing heat output from high temperature gas reactors (HTGR). Calcium oxide/carbon dioxide reactivity for the heat pump was measured using a packed bed reactor containing 1.0 kg of reactant. The reactor was capable of storing heat at 900 deg. C by decarbonation of calcium carbonate and generating up to 997 deg. C by carbonation of calcium oxide. The amount of stored heat in the reactor was 800-900 kJ kg -1 . The output temperature of the reactor could be controlled by regulating the carbonation pressure. The thermal storage performance of the reactor was superior to that of conventional sensible heat storage systems. A heat pump using this CaO/CO 2 reactor is expected to contribute to thermal load leveling and to realize highly efficient utilization of HTGR output due to the high heat storage density and high-quality temperature output of the heat pump

  8. Effect of packing fraction variations on reactivity in pebble-bed reactor

    International Nuclear Information System (INIS)

    Snoj, L.; Ravnik, M.

    2004-01-01

    The pebble-bed reactor (PBR) core consists of large number of randomly packed spherical fuel elements. The effect of fuel element packing density variations on multiplication factor in a typical PBR is studied using WIMS code. It is observed that at normal conditions the k-eff increases with packing fraction. Effects of secondary coolant ingress (water or molten lead) in the core at accidental conditions are studied at various packing densities. The effect of water ingress on reactivity depends strongly on water density and packing fraction and is prevailingly positive, while the lead ingress reduces multiplication factor regardless of lead effective density and packing fraction. Both effects are stronger at lower packing fractions. (author)

  9. Improved performance of parallel surface/packed-bed discharge reactor for indoor VOCs decomposition: optimization of the reactor structure

    International Nuclear Information System (INIS)

    Jiang, Nan; Hui, Chun-Xue; Li, Jie; Lu, Na; Shang, Ke-Feng; Wu, Yan; Mizuno, Akira

    2015-01-01

    The purpose of this paper is to develop a high-efficiency air-cleaning system for volatile organic compounds (VOCs) existing in the workshop of a chemical factory. A novel parallel surface/packed-bed discharge (PSPBD) reactor, which utilized a combination of surface discharge (SD) plasma with packed-bed discharge (PBD) plasma, was designed and employed for VOCs removal in a closed vessel. In order to optimize the structure of the PSPBD reactor, the discharge characteristic, benzene removal efficiency, and energy yield were compared for different discharge lengths, quartz tube diameters, shapes of external high-voltage electrode, packed-bed discharge gaps, and packing pellet sizes, respectively. In the circulation test, 52.8% of benzene was removed and the energy yield achieved 0.79 mg kJ −1 after a 210 min discharge treatment in the PSPBD reactor, which was 10.3% and 0.18 mg kJ −1 higher, respectively, than in the SD reactor, 21.8% and 0.34 mg kJ −1 higher, respectively, than in the PBD reactor at 53 J l −1 . The improved performance in benzene removal and energy yield can be attributed to the plasma chemistry effect of the sequential processing in the PSPBD reactor. The VOCs mineralization and organic intermediates generated during discharge treatment were followed by CO x selectivity and FT-IR analyses. The experimental results indicate that the PSPBD plasma process is an effective and energy-efficient approach for VOCs removal in an indoor environment. (paper)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  11. A Preliminary Study of the Effect of Shifts in Packing Fraction on k-effective in Pebble-Bed Reactors

    International Nuclear Information System (INIS)

    Ougouag, Abderrafi Mohammed-El-Ami; Terry, William Knox

    2001-01-01

    A preliminary examination of the effect of pebble packing changes on the reactivity of a pebble-bed reactor (PBR) is performed. As a first step, using the MCNP code, the modeling of a PBR core as a continuous and homogeneous region is compared to the modeling as a collection of discrete pebbles of equal average fuel density. It is shown that the two modeling approaches give the same trends inasmuch as changes in keff are concerned. It is thus shown that for the purpose of identifying trends in keff changes, the use of a homogeneous model is sufficient. A homogeneous model is then used to assess the effect of pebble packing arrangement changes on the reactivity of a PBR core. It is shown that the changes can be large enough to result in prompt criticality. It is shown that for uranium fueled PBRs, thermal feedback could have the potential to offset the increase in activity, whereas for plutonium fueled systems, thermal feedback may not be sufficient for totally offsetting the packing-increase reactivity insertion and could even exacerbate the initial response. It is thus shown that a full study, including reactor kinetics, thermal feedback, and the dynamics of energy deposition and removal is warranted to fully characterize the potential consequences of packing shifts

  12. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  13. Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Transport from the membrane to the packed bed

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  14. Biological perchlorate reduction in packed bed reactors using elemental sulfur.

    Science.gov (United States)

    Sahu, Ashish K; Conneely, Teresa; Nüsslein, Klaus R; Ergas, Sarina J

    2009-06-15

    Sulfur-utilizing perchlorate (ClO4-)-reducing bacteria were enriched from a denitrifying wastewater seed with elemental sulfur (S0) as an electron donor. The enrichment was composed of a diverse microbial community, with the majority identified as members of the phylum Proteobacteria. Cultures were inoculated into bench-scale packed bed reactors (PBR) with S0 and crushed oyster shell packing media. High ClO4-concentrations (5-8 mg/L) were reduced to PBR performance decreased when effluent recirculation was applied or when smaller S0 particle sizes were used, indicating that mass transfer of ClO4- to the attached biofilm was not the limiting mechanism in this process, and that biofilm acclimation and growth were key factors in overall reactor performance. The presence of nitrate (6.5 mg N/L) inhibited ClO4- reduction. The microbial community composition was found to change with ClO4- availability from a majority of Beta-Proteobacteria near the influent end of the reactor to primarily sulfur-oxidizing bacteria near the effluent end of the reactor.

  15. Experimental and modelling study of drinking water hydrogenotrophic denitrification in packed-bed reactors

    International Nuclear Information System (INIS)

    Vasiliadou, I.A.; Karanasios, K.A.; Pavlou, S.; Vayenas, D.V.

    2009-01-01

    The aim of this work was to study hydrogenotrophic denitrification in packed-bed reactors under draw-fill and continuous operation. Three bench-scale packed-bed reactors with gravel in different sizes (mean diameter 1.75, 2.41 and 4.03 mm) as support media were used, in order to study the effect of particle size on reactors performance. The maximum denitrification rate achieved under draw-fill operation was 4.4 g NO 3 - -N/ld for the filter with gravel of 2.41 mm. This gravel size was chosen to perform experiments under continuous operation. Feed NO 3 - -N concentrations and hydraulic loadings (HL) ranged between 20-200 mg/l and 5.7-22.8 m 3 /m 2 d, respectively. A comparison between the two operating modes showed that, for low HL the draw-fill operation achieved higher denitrification rates, while for high HL and intermediate feed concentrations (40-60 mg NO 3 - -N/l) the continuous operation achieved higher denitrification rates (4.67-5.65 g/ld). Finally, experiments with three filters in series (with gravels of 4.03, 2.41 and 1.75 mm mean diameter) were also performed under continuous operation. The maximum denitrification rate achieved was 6.2 g NO 3 - -N/ld for feed concentration of 340 mg/l and HL of 11.5 m 3 /m 2 d. A model, which describes denitrification in packed-bed reactors, was also developed. The model predicts the concentration profiles of NO 3 - -N along filter height, in draw-fill as well as in continuous operation, satisfactorily.

  16. Model description and kinetic parameter analysis of MTBE biodegradation in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A dynamic modeling approach was used to estimate in-situ model parameters, which describe the degradation of methyl tert-butyl ether (MTBE) in a laboratory packed bed reactor. The measured dynamic response of MTBE pulses injected at the reactor's inlet was analyzed by least squares and parameter...

  17. Aerobic biodegradation of a sulfonated phenylazonaphthol dye by a bacterial community immobilized in a multistage packed-bed BAC reactor.

    Science.gov (United States)

    Ruiz-Arias, Alfredo; Juárez-Ramírez, Cleotilde; de los Cobos-Vasconcelos, Daniel; Ruiz-Ordaz, Nora; Salmerón-Alcocer, Angélica; Ahuatzi-Chacón, Deifilia; Galíndez-Mayer, Juvencio

    2010-11-01

    A microbial community able to aerobically degrade the azo dye Acid Orange 7 was selected from riparian or lacustrine sediments collected at sites receiving textile wastewaters. Three bacterial strains, pertaining to the genera Pseudomonas, Arthrobacter, and Rhizobium, constitute the selected community. The biodegradation of AO7 was carried out in batch-suspended cell culture and in a continuously operated multistage packed-bed BAC reactor. The rapid decolorization observed in batch culture, joined to a delay of about 24 h in COD removal and cell growth, suggests that enzymes involved in biodegradation of the aromatic amines generated after AO7 azo-bond cleavage (1-amino-2-naphthol [1-A2N] and 4-aminobenzenesulfonic acid [4-ABS]), are inducible in this microbial consortium. After this presumptive induction period, the accumulated byproducts, measured through COD, were partially metabolized and transformed in cell mass. At all azo dye loading rates used, complete removal of AO7 and 1-A2N was obtained in the multistage packed-bed BAC reactor (PBR).; however, the overall COD (eta ( COD )) and 4-ABS (eta ( ABS )) removal efficiencies obtained in steady state continuous culture were about 90%. Considering the toxicity of 1-A2N, its complete removal has particular relevance. In the first stages of the packed-bed BAC reactor (Fig. 4a-c), major removal was observed. In the last stage, only a slight removal of COD and 4-ABS was obtained. Comparing to several reported studies, the continuously operated multistage packed-bed BAC reactor showed similar or superior results. In addition, the operation of large-packed-bed BAC reactors could be improved by using several shallow BAC bed stages, because the pressure drop caused by bed compaction of a support material constituted by small and fragile particles can be reduced.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  19. Inulinase production in a packed bed reactor by solid state fermentation.

    Science.gov (United States)

    Dilipkumar, M; Rajamohan, N; Rajasimman, M

    2013-07-01

    In this work, production of inulinase was carried out in a packed bed reactor (PBR) under solid state fermentation. Kluyveromyces marxianus var. marxianus was used to produce the inulinase using pressmud as substrate. The parameters like air flow rate, packing density and particle size were optimized using response surface methodology (RSM) to maximize the inulinase production. The optimum conditions for the maximum inulinase production were: air flow rate - 0.82 L/min, packing density - 40 g/L and particle size - 0.0044 mm (mesh - 14/20). At these optimized conditions, the production of inulinase was found to be 300.5 unit/gram of dry substrate (U/gds). Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Production of structured lipids in a packed-bed reactor with Thermomyces lanuginosa lipase

    DEFF Research Database (Denmark)

    Xu, Xuebing; Porsgaard, Trine; Zhang, Hong

    2002-01-01

    Lipase-catalyzed interesterification between fish oil and medium-chain TAG has been investigated in a packed-bed reactor with a commercially immobilized enzyme. The enzyme, a Thermomyces lanuginosa lipase immobilized on silica by granulation (Lipozyme TL IM; Novozymes A/S, Bagsvaerd, Denmark), ha...

  1. A thermal packed-bed reactor and a silent discharge plasma cell for a two-stage treatment system

    International Nuclear Information System (INIS)

    Godoy-Cabrera, O G; Lopez-Callejas, R; Mercado-Cabrera, A; Barocio, S R; Valencia, R; Munoz-Castro, A; Eguiluz, R Pena; Piedad-Beneitez, A de la

    2006-01-01

    Dielectric barrier discharge cells (DBDCs) have proved their efficiency in the generation of cold plasmas for hazardous organic compound degradation. Here, we describe the design and construction of a dual thermal packed-bed reactor and DBDC-based system to carry out the degradation of hazardous organic compounds in both liquid and gas phases. The main components of this system are: (i) the thermal treatment system (ii) DBDC and (iii) resonant inverters of low (3.3 kHz) and high (100 kHz) calculated frequencies. The definition of the cell physical parameters considers: (a) a first-order degradation ratio of the compound and (b) the air breakdown at atmospheric pressure as a function of the transport carrier gas. The power consumed by the cells during the discharges was computed theoretically and experimentally. Using the dual system along with a gas chromatography diagnostic system, highly efficient degradations of a test compound (benzene) have been obtained, reaching 99.950% in the case of a cell experimentally operated at 3.3 kHz and up to 99.996% in another one at 94.3 kHz. An additional 3.7 times reduction in the latter case residence time with respect to the low frequency cell has been found

  2. Optimization of a packed bed reactor for liquid waste treatment

    International Nuclear Information System (INIS)

    Schmidt, C.A.; Brower, M.J.; Coogan, J.J.; Tennant, R.A.

    1993-01-01

    The authors describe an optimization study of a packed bed reactor (PBR), developed for the treatment of hazardous liquid wastes. The focus is on the destruction of trichloroethylene (TCE). The PBR technology offers many distinct advantages over other processes: simple design, high destruction rates (99.99%), low costs, ambient pressure operation, easy maintenance and scaleability. The cost effectiveness, optimal operating parameters and scaleability were determined. As a second stage of treatment, a silent discharge plasma (SDP) reactor was installed to further treat offgases from the PBR. A primary advantage of this system is closed loop operation, where exhaust gases are continuously recycled and not released into the atmosphere

  3. [Rapid startup and nitrogen removal characteristic of anaerobic ammonium oxidation reactor in packed bed biofilm reactor with suspended carrier].

    Science.gov (United States)

    Chen, Sheng; Sun, De-zhi; Yu, Guang-lu

    2010-03-01

    Packed bed biofilm reactor with suspended carrier was used to cultivate ANAMMOX bacteria with sludge inoculums from WWTP secondary settler. The startup of ANAMMOX reactor was comparatively studied using high nitrogen loading method and low nitrogen loading method with aerobically biofilmed on the carrier, and the nitrogen removal characteristic was further investigated. The results showed that the reactor could be started up successfully within 90 days using low nitrogen loading method, the removal efficiencies of ammonium and nitrite were nearly 100% and the TN removal efficiencywas over 75% , however, the high nitrogen loading method was proved unsuccessfully for startup of ANAMMOX reactor probably because of the inhibition effect of high concentration of ammonium and nitrite. The pH value of effluent was slightly higher than the influent and the pH value can be used as an indicator for the process of ANAMMOX reaction. The packed bed ANAMMOX reactor with suspended carrier showed good characteristics of high nitrogen loading and high removal efficiency, 100% of removal efficiency could be achieved when the influent ammonium and nitrite concentration was lower than 800 mg/L.

  4. Research and application of packing density for pebble bed in HTR

    International Nuclear Information System (INIS)

    Yu Fujiang; Xie Fei; Sun Ximing

    2015-01-01

    The pebble bed high temperature gas-cooled reactor is one of the major types of reactors developed by Chinese nuclear technology. The statistical analysis for packing density in the pebble bed is an important issue of physical-thermal calculation and safety analysis. Aimed to this problem, a new kind of method was set up to solve this problem. Compared with the traditional lattice-fill method and the experiment, its efficiency and accuracy were verified, while helping to find out the best length of unit in the traditional lattice-fill method. This method was used to analyze the boundary effects observed by experiments. (authors)

  5. Electrical Capacitance Volume Tomography for the Packed Bed Reactor ISS Flight Experiment

    Science.gov (United States)

    Marashdeh, Qussai; Motil, Brian; Wang, Aining; Liang-Shih, Fan

    2013-01-01

    Fixed packed bed reactors are compact, require minimum power and maintenance to operate, and are highly reliable. These features make this technology a highly desirable unit operation for long duration life support systems in space. NASA is developing an ISS experiment to address this technology with particular focus on water reclamation and air revitalization. Earlier research and development efforts funded by NASA have resulted in two hydrodynamic models which require validation with appropriate instrumentation in an extended microgravity environment. To validate these models, the instantaneous distribution of the gas and liquid phases must be measured.Electrical Capacitance Volume Tomography (ECVT) is a non-invasive imaging technology recently developed for multi-phase flow applications. It is based on distributing flexible capacitance plates on the peripheral of a flow column and collecting real-time measurements of inter-electrode capacitances. Capacitance measurements here are directly related to dielectric constant distribution, a physical property that is also related to material distribution in the imaging domain. Reconstruction algorithms are employed to map volume images of dielectric distribution in the imaging domain, which is in turn related to phase distribution. ECVT is suitable for imaging interacting materials of different dielectric constants, typical in multi-phase flow systems. ECVT is being used extensively for measuring flow variables in various gas-liquid and gas-solid flow systems. Recent application of ECVT include flows in risers and exit regions of circulating fluidized beds, gas-liquid and gas-solid bubble columns, trickle beds, and slurry bubble columns. ECVT is also used to validate flow models and CFD simulations. The technology is uniquely qualified for imaging phase concentrations in packed bed reactors for the ISS flight experiments as it exhibits favorable features of compact size, low profile sensors, high imaging speed, and

  6. Porous structure analysis of large-scale randomly packed pebble bed in high temperature gas-cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Cheng; Yang, Xingtuan; Liu, Zhiyong; Sun, Yanfei; Jiang, Shengyao [Tsinghua Univ., Beijing (China). Key Laboratory of Advanced Reactor Engineering and Safety; Li, Congxin [Ministry of Environmental Protection of the People' s Republic of China, Beijing (China). Nuclear and Radiation Safety Center

    2015-02-15

    A three-dimensional pebble bed corresponding to the randomly packed bed in the heat transfer test facility built for the High Temperature Reactor Pebble bed Modules (HTR-PM) in Shandong Shidaowan is simulated via discrete element method. Based on the simulation, we make a detailed analysis on the packing structure of the pebble bed from several aspects, such as transverse section image, longitudinal section image, radial and axial porosity distributions, two-dimensional porosity distribution and coordination number distribution. The calculation results show that radial distribution of porosity is uniform in the center and oscillates near the wall; axial distribution of porosity oscillates near the bottom and linearly varies along height due to effect of gravity; the average coordination number is about seven and equals to the maximum coordination number frequency. The fully established three-dimensional packing structure analysis of the pebble bed in this work is of fundamental significance to understand the flow and heat transfer characteristics throughout the pebble-bed type structure.

  7. Evaluation of Packed-Bed Reactor and Continuous Stirred Tank Reactor for the Production of Colchicine Derivatives

    OpenAIRE

    Dubey, Kashyap Kumar; Kumar, Dhirendra; Kumar, Punit; Haque, Shafiul; Jawed, Arshad

    2013-01-01

    Bioconversion of colchicine into its pharmacologically active derivative 3-demethylated colchicine (3-DMC) mediated by P450BM3 enzyme is an economic and promising strategy for the production of this inexpensive and potent anticancer drug. Continuous stirred tank reactor (CSTR) and packed-bed reactor (PBR) of 3 L and 2 L total volumes were compared for the production of 3-demethylated colchicine (3-DMC) a colchicine derivative using Bacillus megaterium MTCC*420 under aerobic conditions. Statis...

  8. Continuous thermophilic biohydrogen production in packed bed reactor

    International Nuclear Information System (INIS)

    Roy, Shantonu; Vishnuvardhan, M.; Das, Debabrata

    2014-01-01

    Highlights: • Continuous H 2 production in whole cell immobilized system was compared with CSTR. • Suitability of environment friendly support matrix for immobilization of whole cells was explored. • Pack bed reactor showed higher stability as compared to CSTR at lower HRTs. • Flow cytometry study showed the influence of recycle ratio on viability of cells. • Novel approach to find out the effect of NADH/NAD + ratio during H 2 production. - Abstract: The present research work deals with the performance of packed bed reactor for continuous H 2 production using cane molasses as a carbon source. Maximum H 2 production rate of 1.7 L L −1 h −1 was observed at a dilution rate and recycle ratio of 0.8 h −1 and 0.6, respectively which was corresponding to the lowest NADH/NAD + ratio. This suggests that the utilization of NADH pool for H 2 and metabolite production might lead to decrement in NADH/NAD + ratio. Thus NADH/NAD + ratio show inverse relation with hydrogen production. The substrate degradation kinetics was investigated as a function of flow rate considering the external film diffusion model. At a flow rate of 245 mL h −1 , the contribution of external film mass transfer coefficient and first order substrate degradation constant were 55.4% and 44.6% respectively. Recycle ratio of 0.6 improved the hydrogen production rates by 9%. The viable cell count was directly proportional to the recycle ratio (within the range 0.1–0.6). Taguchi design showed the significant influence of the feed pH on continuous H 2 production followed by dilution rate and recycle ratio. Thus environmentally friendly and cheaper solid matrix like coconut coir could be efficiently used for thermophilic continuous hydrogen production

  9. Thermo-catalytic pyrolysis of waste polyethylene bottles in a packed bed reactor with different bed materials and catalysts

    International Nuclear Information System (INIS)

    Obeid, Farah; Zeaiter, Joseph; Al-Muhtaseb, Ala’a H.; Bouhadir, Kamal

    2014-01-01

    Highlights: • Thermo-catalytic pyrolysis of waste polyethylene bottles was investigated. • The highest yield of liquid (82%) was obtained over a cement powder bed. • Acidic catalysts narrowed the carbon chain length of the paraffins to C 10 –C 28 . • Combination of cement bed with HBeta catalyst gave the highest yield of liquid. • Significant yield of aromatics was obtained mainly naphthalene and D-limonene. - Abstract: Plastic waste is an increasing economic and environmental problem as such there is a great need to process this waste and reduce its environmental impact. In this work, the pyrolysis of high density polyethylene (HDPE) waste products was investigated using both thermal and catalytic cracking techniques. The experimental work was carried out using packed bed reactor operating under an inert atmosphere at 450 °C. Different reactor bed materials, including sand, cement and white clay were used to enhance the thermal cracking of HDPE. In addition, the catalytic effect of sodium hydroxide, HUSY and HBeta zeolite catalysts on the degradation of HDPE waste was also investigated. The reactor beds were found to significantly alter the yield as well as the product composition. Products such as paraffins (⩽C 44 ), olefins (⩽C 22 ), aromatics (⩽C 14 ) and alcohols (C 16 and C 17 ) were obtained at varying rates. The highest yield of liquid (82%) was obtained over a cement powder bed with a paraffin yield of 58%. The yield of paraffins and olefins followed separate paths, for paraffins it was found to increase in the order or Cement > White clay > Silica Sand, whereas for the olefins it was in the reverse order Silica Sand > White clay > Cement. The results obtained in this work exhibited a higher P/O ratio than expected, where the amount of generated paraffins was greater than 60% in most cases. Less olefin was generated as a consequence. This indicates that the product generated is more suited to be used as a fuel rather than as a chemical

  10. Packed bed reactor for degradation of simulated cyanide-containing wastewater

    OpenAIRE

    Kumar, Virender; Kumar, Vijay; Bhalla, Tek Chand

    2014-01-01

    The discharge of cyanide-containing effluents into the environment contaminates water bodies and soil. Effective methods of treatment which can detoxify cyanide are the need of the hour. The aim of the present study is to develop a bioreactor for complete degradation of cyanide using immobilized cells of Serratia marcescens RL2b. Alginate-entrapped cells of S. marcescens RL2b were used for complete degradation of cyanide in a packed bed reactor (PBR). Cells grown in minimal salt medium (pH 6....

  11. Experimental investigation into a packed bed thermal storage solution for solar gas turbine systems

    CSIR Research Space (South Africa)

    Klein, P

    2013-09-01

    Full Text Available High temperature thermal storage in randomly packed beds of ceramic particles is proposed as an effective storage solution for Solar Gas Turbine (SGT) cycles in the near term. Numerical modelling of these systems allows for optimised thermal storage...

  12. Packed bed reactor treatment of liquid hazardous and mixed wastes

    International Nuclear Information System (INIS)

    Tennant, R.A.; Wantuck, P.J.; Vargas, R.

    1992-01-01

    We are developing thermal-based packed bed reactor (PBR) technology as an alternative to incineration for treatment of hazardous organic liquid wastes. The waste streams targeted by this technology are machining fluids contaminated with chlorocarbons and/or chlorofluorocarbons and low levels of plutonium or tritium The PBR offers several distinct advantages including simplistic design, rugged construction, ambient pressure processing, economical operations, as well as ease of scalability and maintainability. In this paper, we provide a description of the apparatus as well as test results using prepared mixtures of machining oils/emulsions with trichloroethylene (TCE), carbon tetrachloride (CCl 4 ), trichloroethane (TCA), and Freon TF. The current treatment system is configured as a two stage device with the PBR (1st stage) coupled to a silent discharge plasma (SDP) cell. The SDP serves as a second stage for further treatment of the gaseous effluent from the PBR. One of the primary advantages of this two stage system is that its suitability for closed loop operation where radioactive components are well contained and even CO 2 is not released to the environment

  13. Galacto-oligosaccharide production with immobilized ß-galactosidase in a packed-bed reactor vs. free ß-galactosidase in a batch reactor

    NARCIS (Netherlands)

    Warmerdam, A.; Benjamins, E.; Leeuw de, T.F.; Broekhuis, T.A.; Boom, R.M.; Janssen, A.E.M.

    2014-01-01

    We report here that the usage of immobilized enzyme in a continuous packed bed reactor (PBR) can be a good alternative for GOS production instead of the traditional use of free enzyme in a batch reactor. The carbohydrate composition of the product of the PBR with immobilized enzyme was comparable to

  14. Numerical modelling for the effective thermal conductivity of lithium meta titanate pebble bed with different packing structures

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Maulik, E-mail: maulikpanchal@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India); Chaudhuri, Paritosh [Institute for Plasma Research, Bhat, Gandhinagar-382428 (India); Van Lew, Jon T; Ying, Alice [UCLA, MAE Department, Los Angeles, CA 90095-1597 (United States)

    2016-11-15

    Highlights: • The effective thermal conductivity (k{sub eff}) of lithium meta-titanate (Li{sub 2}TiO{sub 3}) pebble beds is an important parameter for the design and analysis of TBM in ITER. • The k{sub eff} of Li{sub 2}TiO{sub 3} pebble beds under stagnant helium gas have been determined numerically using different uniform packing structures and random close packing (RCP) structures. • k{sub eff} of Li{sub 2}TiO{sub 3} pebble beds with different packing fractions have been reported as function of temperature; k{sub eff} of the RCP Li{sub 2}TiO{sub 3} pebble bed is compared with reported experimental results. • The numerically-determined k{sub eff} of the RCP Li{sub 2}TiO{sub 3} pebble bed agrees reasonably well with the experimental data and Zehner-Schlunder correlation. - Abstract: The effective thermal conductivity (k{sub eff}) of lithium meta-titanate (Li{sub 2}TiO{sub 3}) pebble beds is an important parameter for the design and analysis of IN LLCB TBM (Indian Lead Lithium Ceramic Breeder Test Blanket Module). The k{sub eff} of Li{sub 2}TiO{sub 3} pebble beds under stagnant helium gas have been determined numerically using different uniform packing structures and random close packing (RCP) structures. The uniform packing structures of Li{sub 2}TiO{sub 3} pebble bed are modelled by using the simple cubic, body centered cubic and face centered cubic arrangement. The packing structure of the RCP bed of Li{sub 2}TiO{sub 3} pebbles is generated with the discrete element method (DEM) code. k{sub eff} of Li{sub 2}TiO{sub 3} pebble beds with different packing fractions have been reported as function of temperature; k{sub eff} of the RCP Li{sub 2}TiO{sub 3} pebble bed is compared with reported experimental results from literature. The numerically determined k{sub eff} of the Li{sub 2}TiO{sub 3} pebble bed agrees reasonably well with the experimental data.

  15. Reactor design and operation strategies for a large-scale packed-bed CLC power plant with coal syngas

    NARCIS (Netherlands)

    Spallina, V.; Chiesa, P.; Martelli, E; Gallucci, F.; Romano, M.C.; Lozza, G.; Sint Annaland, van M.

    2015-01-01

    This paper deals with the design and operation strategies of dynamically operated packed-bed reactors (PBRs) of a chemical looping combustion (CLC) system included in an integrated gasification combined cycle (IGCC) for electric power generation with low CO2 emission from coal. The CLC reactors,

  16. A bibliographic review of mathematical models of packed-bed biological reactors (PBR

    Directory of Open Access Journals (Sweden)

    Deisy Corredor

    2005-09-01

    Full Text Available Several authors have sublected packed-bed biological reactors to mathematical and theoretical analysis. They have taken reaction kinetics and single-dimensional, homogeneous, pseudo-homogeneous and heterogeneous models into account. Numerical methods have provided the set of equations so developed. The effect of physically important process variables in terms of design and operation have been investigated (i.e. residence time, operating- flow, substrate conversion, bio-film area and film thickness.

  17. Butanol production by Clostridium acetobutylicum in a continuous packed bed reactor.

    Science.gov (United States)

    Napoli, Fabio; Olivieri, Giuseppe; Russo, Maria Elena; Marzocchella, Antonio; Salatino, Piero

    2010-06-01

    In this study, we report on a butanol production process by immobilized Clostridium acetobutylicum in a continuous packed bed reactor (PBR) using Tygon rings as a carrier. The medium was a solution of lactose (15-30 g/L) and yeast extract (3 g/L) to emulate the cheese whey, an abundant lactose-rich wastewater. The reactor was operated under controlled conditions with respect to the pH and to the dilution rate. The pH and the dilution rate ranged between 4 and 5, the dilution rate between 0.54 and 2.4 h(-1) (2.5 times the maximum specific growth rate assessed for suspended cells). The optimal performance of the reactor was recorded at a dilution rate of 0.97 h(-1): the butanol productivity was 4.4 g/Lh and the selectivity of solvent in butanol was 88%(w).

  18. Transformation of carbon tetrachloride in an anaerobic packed-bed reactor without addition of another electron donor

    NARCIS (Netherlands)

    de Best, JH; Hunneman, P; Doddema, HJ; Janssen, DB; Harder, W; Doddema, Hans J.

    1999-01-01

    Carbon tetrachloride (52 mu M) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were

  19. Transformation of carbon tetrachloride in an anaerobic packed-bed reactor without addition of another electron donor

    NARCIS (Netherlands)

    Best, J.H. de; Hunneman, P.; Doddema, H.J.; Janssen, D.B.; Harder, W.

    1999-01-01

    Carbon tetrachloride (52 μM) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were

  20. Packed bed reactor for degradation of simulated cyanide-containing wastewater.

    Science.gov (United States)

    Kumar, Virender; Kumar, Vijay; Bhalla, Tek Chand

    2015-10-01

    The discharge of cyanide-containing effluents into the environment contaminates water bodies and soil. Effective methods of treatment which can detoxify cyanide are the need of the hour. The aim of the present study is to develop a bioreactor for complete degradation of cyanide using immobilized cells of Serratia marcescens RL2b. Alginate-entrapped cells of S. marcescens RL2b were used for complete degradation of cyanide in a packed bed reactor (PBR). Cells grown in minimal salt medium (pH 6.0) were harvested after 20 h and exhibited 0.4 U mg -1  dcw activity and 99 % cyanide degradation in 10 h. These resting cells were entrapped using 3 % alginate beads and packed in a column reactor (20 × 1.7 cm). Simulated cyanide (12 mmol l -1 )-containing wastewater was loaded and fractions were collected after different time intervals at various flow rates. Complete degradation of 12 m mmol l -1 (780 mg l -1 ) cyanide in 10 h was observed at a flow rate of 1.5 ml h -1 . The degradation of cyanide in PBR showed direct dependence on retention time. The retention time of cyanide in the reactor was 9.27 h. The PBR can degrade 1.2 g of cyanide completely in 1 day.

  1. Immobilised native plant cysteine proteases: packed-bed reactor for white wine protein stabilisation

    OpenAIRE

    Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Acciaro, Giuseppe; Zappino, Matteo; Esti, Marco

    2015-01-01

    This research presents a feasibility study of using a continuous packed-bed reactor (PBR), containing immobilised native plant cysteine proteases, as a specific and mild alternative technique relative to the usual bentonite fining for white wine protein stabilisation. The operational parameters for a PBR containing immobilised bromelain (PBR-br) or immobilised papain (PBR-pa) were optimised using model wine fortified with synthetic substrate (Bz-Phe-Val-Arg-pNA). The effectiveness of PBR-br, ...

  2. Continuous production of lipase-catalyzed biodiesel in a packed-bed reactor: optimization and enzyme reuse study.

    Science.gov (United States)

    Chen, Hsiao-Ching; Ju, Hen-Yi; Wu, Tsung-Ta; Liu, Yung-Chuan; Lee, Chih-Chen; Chang, Cheng; Chung, Yi-Lin; Shieh, Chwen-Jen

    2011-01-01

    An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

  3. A methodology to investigate the contribution of conduction and radiation heat transfer to the effective thermal conductivity of packed graphite pebble beds, including the wall effect

    Energy Technology Data Exchange (ETDEWEB)

    De Beer, M., E-mail: maritz.db@gmail.com [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Du Toit, C.G., E-mail: Jat.DuToit@nwu.ac.za [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Rousseau, P.G., E-mail: pieter.rousseau@uct.ac.za [Department of Mechanical Engineering, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)

    2017-04-01

    Highlights: • The radiation and conduction components of the effective thermal conductivity are separated. • Near-wall effects have a notable influence on the effective thermal conductivity. • Effective thermal conductivity is a function of the macro temperature gradient. • The effective thermal conductivity profile shows a characteristic trend. • The trend is a result of the interplay between conduction and radiation. - Abstract: The effective thermal conductivity represents the overall heat transfer characteristics of a packed bed of spheres and must be considered in the analysis and design of pebble bed gas-cooled reactors. During depressurized loss of forced cooling conditions the dominant heat transfer mechanisms for the passive removal of decay heat are radiation and conduction. Predicting the value of the effective thermal conductivity is complex since it inter alia depends on the temperature level and temperature gradient through the bed, as well as the pebble packing structure. The effect of the altered packing structure in the wall region must therefore also be considered. Being able to separate the contributions of radiation and conduction allows a better understanding of the underlying phenomena and the characteristics of the resultant effective thermal conductivity. This paper introduces a purpose-designed test facility and accompanying methodology that combines physical measurements with Computational Fluid Dynamics (CFD) simulations to separate the contributions of radiation and conduction heat transfer, including the wall effects. Preliminary results obtained with the methodology offer important insights into the trends observed in the experimental results and provide a better understanding of the interplay between the underlying heat transfer phenomena.

  4. Syngas fermentation by Clostridium carboxidivorans P7 in a horizontal rotating packed bed biofilm reactor with enhanced ethanol production

    International Nuclear Information System (INIS)

    Shen, Yanwen; Brown, Robert C.; Wen, Zhiyou

    2017-01-01

    Highlights: • A novel a horizontal rotating packed bed (h-RPB) reactor for syngas fermentation was reported. • The h-RPB reactor enhanced ethanol productivity by 3.3-folds compared to continuous stirred tank reactor (CSTR). • The h-RPB reactor has a unique feature of transfer gas from both bulk liquid phase and headspace phase. • The mass transfer in the headspace of h-PRB played an important role for enhanced ethanol production. - Abstract: Gasification of lignocellulosic biomass followed by syngas fermentation is a promising process for producing fuels and chemicals. Syngas fermentation, however, is commonly limited by low mass transfer rates. In this work, a horizontally oriented rotating packed bed (h-RPB) reactor was developed to improve mass transfer and enhance ethanol production. In the h-RPB reactor, cell attachment materials were packed in the reactor and half submerged in the liquid and half exposed to the headspace. With continuous rotation of the packing materials, the cells in biofilm were alternately in contact with liquid and headspace; thus, transport of syngas to the cells occurred in both the liquid phase and headspace. The volumetric mass transfer coefficient (k_La) of the h-RPB reactor was lower than that in a traditional continuous stirred tank reactor (CSTR), indicating the mass transfer in the liquid phase of h-PRB was lower than CSTR, and the mass transfer in the headspace phase played an important role in syngas fermentation. The syngas fermentation of Clostridium carboxidivorans P7 in h-RPB resulted in a 7.0 g/L titer and 6.7 g/L/day productivity of ethanol, respectively, 3.3 times higher than those obtained in a CSTR under the same operational conditions. The results demonstrate that the h-RPB reactor is an efficient system for syngas fermentation, making cellulosic ethanol biorefinery one step closer to technical and economic feasibility.

  5. Packed-fluidized-bed blanket concept for a thorium-fueled commercial tokamak hybrid reactor

    International Nuclear Information System (INIS)

    Chi, J.W.H.; Miller, J.W.; Karbowski, J.S.; Chapin, D.L.; Kelly, J.L.

    1980-09-01

    A preliminary design of a thorium blanket was carried out as a part of the Commercial Tokamak Hybrid Reactor (CTHR) study. A fixed fuel blanket concept was developed as the reference CTHR blanket with uranium carbide fuel and helium coolant. A fixed fuel blanket was initially evaluated for the thorium blanket study. Subsequently, a new type of hybrid blanket, a packed-fluidized bed (PFB), was conceived. The PFB blanket concept has a number of unique features that may solve some of the problems encountered in the design of tokamak hybrid reactor blankets. This report documents the thorium blanket study and describes the feasibility assessment of the PFB blanket concept

  6. Storage capacity assessment of liquid fuels production by solar gasification in a packed bed reactor using a dynamic process model

    International Nuclear Information System (INIS)

    Kaniyal, Ashok A.; Eyk, Philip J. van; Nathan, Graham J.

    2016-01-01

    Highlights: • First analysis to assess storage requirements of a stand-alone packed bed, batch process solar gasifier. • 35 days of storage required for stand-alone solar system, whereas 8 h of storage required for hybrid system. • Sensitivity of storage requirement to reactor operation, solar region and solar multiple evaluated. - Abstract: The first multi-day performance analysis of the feasibility of integrating a packed bed, indirectly irradiated solar gasification reactor with a downstream FT liquids production facility is reported. Two fuel-loading scenarios were assessed. In one, the residual unconverted fuel at the end of a day is reused, while in the second, the residual fuel is discarded. To estimate a full year time-series of operation, a simplified statistical model was developed from short-period simulations of the 1-D heat transfer, devolatilisation and gasification chemistry model of a 150 kW th packed bed reactor (based on the authors’ earlier work). The short time-series cover a variety of solar conditions to represent seasonal, diurnal and cloud-induced solar transience. Also assessed was the influence of increasing the solar flux incident at the emitter plate of the packed bed reactor on syngas production. The combination of the annual time-series and daily model of syngas production was found to represent reasonably the seasonal transience in syngas production. It was then used to estimate the minimum syngas storage volume required to maintain a stable flow-rate and composition of syngas to a FT reactor over a full year of operation. This found that, for an assumed heliostat field collection area of 1000 m 2 , at least 64 days of storage is required, under both the Residual Fuel Re-Use and Discard scenarios. This figure was not sensitive to the two solar sites assessed, Farmington, New Mexico or Tonopah Airport, Nevada. Increasing the heliostat field collection area from 1000 to 1500 m 2 , led to an increase in the calculated daily rate

  7. Oxygen distribution in packed-bed membrane reactors for partial oxidations: effect of the radial porosity profiles on the product selectivity

    NARCIS (Netherlands)

    Kurten, U.; van Sint Annaland, M.; Kuipers, J.A.M.

    2004-01-01

    A two-dimensional, pseudohomogeneous reactor model was presented to describe the radial and axial concentration profiles in a packed-bed membrane reactor and the local velocity field while accounting for the influences due to the distributive membrane flow and the radial porosity profile. The effect

  8. Steady-state thermal-hydraulic analysis of the pellet-bed reactor for nuclear thermal propulsion

    International Nuclear Information System (INIS)

    El-Genk, M.S.; Morley, N.J.; Yang, J.Y.

    1992-01-01

    The pellet-bed reactor (PBR) for nuclear thermal propulsion is a hydrogen-cooled, BeO-reflected, fast reactor, consisting of an annular core region filled with randomly packed, spherical fuel pellets. The fuel pellets in the PBR are self-supported, eliminating the need for internal core structure, which simplifies the core design and reduces the size and mass of the reactor. Each spherical fuel pellet is composed of hundreds of fuel microspheres embedded in a zirconium carbide (ZrC) matrix. Each fuel microsphere is composed of a UC-NbC fuel kernel surrounded by two consecutive layers of the NbC and ZrC. Gaseous hydrogen serves both as core coolant and as the propellant for the PBR rocket engine. The cold hydrogen flows axially down the inlet channel situated between the core and the external BeO reflector and radially through the orifices in the cold frit, the core, and the orifices in the hot frit. Finally, the hot hydrogen flows axially out the central channel and exits through converging-diverging nozzle. A thermal-hydraulic analysis of the PBR core was performed with an emphasis on optimizing the size and axial distribution of the orifices in the hot and cold frits to ensure that hot spots would not develop in the core during full-power operation. Also investigated was the validity of the assumptions of neglecting the axial conduction and axial cross flow in the core

  9. Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies.

    Science.gov (United States)

    Vadgama, Rajeshkumar N; Odaneth, Annamma A; Lali, Arvind M

    2015-12-01

    Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

  10. Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR studies

    Directory of Open Access Journals (Sweden)

    Rajeshkumar N. Vadgama

    2015-12-01

    Full Text Available Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15 in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

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

    International Nuclear Information System (INIS)

    Stroh, K.R.

    1979-03-01

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

  12. Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

    Directory of Open Access Journals (Sweden)

    Hsiao-Ching Chen

    2011-01-01

    Full Text Available An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435 as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1∘C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31±2.07% and 82.81±.98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

  13. Modeling the methanolysis of triglyceride catalyzed by immobilized lipase in a continuous-flow packed-bed reactor

    International Nuclear Information System (INIS)

    Tran, Dang-Thuan; Lin, Yi-Jan; Chen, Ching-Lung; Chang, Jo-Shu

    2014-01-01

    Highlights: • A Burkholderia lipase was immobilized on alkyl-grafted celite carriers. • Celite-alkyl-lipase catalyzed the methanolysis of triglyceride in packed-bed reactor. • The kinetics of the enzymatic transesterification follows Ping Pong Bi Bi mechanism. • Models were developed to discuss the mass transfer and enzyme kinetics in the PBR. - Abstract: A Burkholderia lipase was immobilized on celite grafted with long alkyl groups. The immobilized lipase-catalyzed methanolysis of sunflower oil in a packed-bed reactor (PBR) follows the Ping Pong Bi Bi mechanism. The external mass transfer and enzymatic reaction that simultaneously occurred in the PBR were investigated via the mathematical models. The overall biodiesel production in the PBR was verified to work in an enzymatic reaction-limited regime. Triglyceride conversion and biodiesel yield were higher under a lower reactant feeding rate, while a larger amount of biocatalyst would be required to achieve the designated conversion rate if a higher reactant feeding rate was employed. The PBR can achieve nearly complete conversion of triglyceride at a biocatalyst bed height of 60 cm (ca. 29 g biocatalyst) and a flow rate of 0.1 ml min −1 , whereas the biodiesel yield was lower than 67%, probably due to the positional specificity of Burkholderia lipase and the accumulation of glycerol

  14. Comparison of Several Thermal Conductivity Constants for Thermal Hydraulic Calculation of Pebble Bed Reactor

    Science.gov (United States)

    Irwanto, Dwi; Setiadipura, Topan; Pramutadi, Asril

    2017-07-01

    There are two type of High Temperature Gas Reactor (HTGR), prismatic and pebble bed. Pebble Bed type has unique configuration because the fuels are randomly distributed inside the reactor core. In term of safety features, Pebble Bed Reactor (PBR) is one of the most promising reactor type in avoiding severe nuclear accidents. In order to analyze heat transfer and safety of this reactor type, a computer code is now under development. As a first step, calculation method proposed by Stroh [1] is adopted. An approach has been made to treat randomly distributed pebble balls contains fissile material inside the reactor core as a porous medium. Helium gas act as coolant on the reactor system are carrying heat flowing in the area between the pebble balls. Several parameters and constants are taken into account in the new developed code. Progress of the development of the code especially comparison of several thermal conductivity constants for a certain PBR-case are reported in the present study.

  15. Thermal-hydraulic considerations for particle bed reactors

    Science.gov (United States)

    Benenati, R.; Araj, K. J.; Horn, F.

    In the design of particle bed reactor (PBR) cores, consideration must be given to the gas coolant channels and their configuration. Neutronics analysis provides the relative volume fractions of the component materials, but these must be arranged in such a manner as to allow proper cooling of all components by the gas flow at relatively low pressure drops. The thermal hydraulic aspects of this problem are addressed. A description of the computer model used in the analysis of the steady state condition is also included. Blowdown tests on hot particle bed fuel elements were carried out and are described.

  16. Simultaneous Coproduction of Hydrogen and Ethanol in Anaerobic Packed-Bed Reactors

    Directory of Open Access Journals (Sweden)

    Cristiane Marques dos Reis

    2014-01-01

    Full Text Available This study evaluated the use of an anaerobic packed-bed reactor for hydrogen production at different hydraulic retention times (HRT (1–8 h. Two reactors filled with expanded clay and fed with glucose (3136–3875 mg L−1 were operated at different total upflow velocities: 0.30 cm s−1 (R030 and 0.60 cm s−1 (R060. The effluent pH of the reactors was maintained between 4 and 5 by adding NaHCO3 and HCl solutions. It was observed a maximum hydrogen production rate of 0.92 L H2 h−1 L−1 in R030 at HRT of 1 h. Furthermore, the highest hydrogen yield of 2.39 mol H2 mol−1 glucose was obtained in R060. No clear trend was observed by doubling the upflow velocities at this experiment. High ethanol production was also observed, indicating that the ethanol-pathway prevailed throughout the experiment.

  17. Modeling of an axial flow, spherical packed-bed reactor for naphtha reforming process in the presence of the catalyst deactivation

    Energy Technology Data Exchange (ETDEWEB)

    Iranshahi, D.; Pourazadi, E.; Paymooni, K.; Bahmanpour, A.M.; Rahimpour, M.R.; Shariati, A. [Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345 (Iran, Islamic Republic of)

    2010-12-15

    Improving the octane number of the aromatics' compounds has always been an important matter in refineries and lots of investigations have been made concerning this issue. In this study, an axial-flow spherical packed-bed reactor (AF-SPBR) is considered for naphtha reforming process in the presence of catalyst deactivation. Model equations are solved by the orthogonal collocation method. The AF-SPBR results are compared with the plant data of a conventional tubular packed-bed reactor (TR). The effects of some important parameters such as pressure and temperature on aromatic and hydrogen production rates and catalyst activity have been investigated. Higher production rates of aromatics can successfully be achieved in this novel reactor. Moreover, results show the capability of flow augmentation in the proposed configuration in comparison with the TR. This study shows the superiority of AF-SPBR configuration to the conventional types. (author)

  18. Microscale packed bed reactor for controlled hydrogen peroxide decomposition as a fuel cell oxidant aboard unmanned undersea vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Lennon, E.; Ocampo, M.; Besser, R.S. [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 (United States); Burke, A.A. [Naval Undersea Warfare Center, Newport, RI 02841 (United States)

    2010-01-01

    The multiphase catalytic decomposition of hydrogen peroxide into water and oxygen is notoriously susceptible to thermal runaway (heat of reaction: -98 kJ mol{sup -1}). The high surface area to volume ratio (S/V) in a microscale packed bed (MPB) reactor (radius 0.5 mm) was investigated for reducing the risk of thermal runaway during hydrogen peroxide decomposition to oxygen intended as a fuel cell oxidant aboard an unmanned undersea vehicle (UUV). A microscale reactor channel with a S/V of {proportional_to}2 x 10{sup 3} m{sup 2} m{sup -3} simulated under convective cooling generated a significant heat rise (T rise {proportional_to} 100 K), whereas a microreactor with a higher S/V ({proportional_to}200 x 10{sup 3} m{sup 2} m{sup -3}) achieved thermal control (T rise < 10 K) over the simulated reaction zone. Although thermal management was successfully accomplished using the higher S/V, experimental conversions of hydrogen peroxide to oxygen (5-18%) measured from the outlet were lower than simulated conversions (38-63%). Simulation assumptions, such as homogeneously dispersed flow and perfect catalyst interaction among other factors, contributed to the discrepancies between the simulated and experimental degrees of peroxide conversion to oxygen. Even though thermal control of the MPB was achieved, this work indicates that mass transfer limitations are a factor in the MPB reactor during a multiphase reaction, like decomposition of hydrogen peroxide to oxygen and water, and suggests means to overcome them even on the microscale level. (author)

  19. Treatment of chemical-pharmaceutical wastewater in packed bed anaerobic reactors

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

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

  20. Ceramic breeder pebble bed packing stability under cyclic loads

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chunbo, E-mail: chunbozhang@fusion.ucla.edu [Fusion Science and Technology Center, University of California, Los Angeles, CA 90095-1597 (United States); Ying, Alice; Abdou, Mohamed A. [Fusion Science and Technology Center, University of California, Los Angeles, CA 90095-1597 (United States); Park, Yi-Hyun [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    Highlights: • The feasibility of obtaining packing stability for pebble beds is studied. • The responses of pebble bed to cyclic loads have been presented and analyzed in details. • Pebble bed packing saturation and its applications are discussed. • A suggestion is made regarding the improvement of pebbles filling technique. - Abstract: Considering the optimization of blanket performance, it is desired that the bed morphology and packing state during reactor operation are stable and predictable. Both experimental and numerical work are performed to explore the stability of pebble beds, in particular under pulsed loading conditions. Uniaxial compaction tests have been performed for both KIT’s Li{sub 4}SiO{sub 4} and NFRI’s Li{sub 2}TiO{sub 3} pebble beds at elevated temperatures (up to 750 °C) under cyclic loads (up to 6 MPa). The obtained data shows the stress-strain loop initially moves towards the larger strain and nearly saturates after a certain number of cyclic loading cycles. The characterized FEM CAP material models for a Li{sub 4}SiO{sub 4} pebble bed with an edge-on configuration are used to simulate the thermomechanical behavior of pebble bed under ITER pulsed operations. Simulation results have shown the cyclic variation of temperature/stress/strain/gap and also the same saturation trend with experiments under cyclic loads. Therefore, it is feasible for pebble bed to maintain its packing stability during operation when disregarding pebbles’ breakage and irradiation.

  1. External Mass Transfer Model for Hydrogen Peroxide Decomposition by Terminox Ultra Catalase in a Packed-Bed Reactor

    Directory of Open Access Journals (Sweden)

    Grubecki Ireneusz

    2017-06-01

    Full Text Available It is known that external diffusional resistances are significant in immobilized enzyme packed-bed reactors, especially at large scales. Thus, the external mass transfer effects were analyzed for hydrogen peroxide decomposition by immobilized Terminox Ultra catalase in a packed-bed bioreactor. For this purpose the apparent reaction rate constants, kP, were determined by conducting experimental works at different superficial velocities, U, and temperatures. To develop an external mass transfer model the correlation between the Colburn factor, JD, and the Reynolds number, Re, of the type JD = K Re(n-1 was assessed and related to the mass transfer coefficient, kmL. The values of K and n were calculated from the dependence (am kp-1 - kR-1 vs. Re-1 making use of the intrinsic reaction rate constants, kR, determined before. Based on statistical analysis it was found that the mass transfer correlation JD = 0.972 Re-0.368 predicts experimental data accurately. The proposed model would be useful for the design and optimization of industrial-scale reactors.

  2. Investigation of hydrodynamic behaviour of a pilot-scale trickle bed reactor packed with hydrophobic and hydrophilic packings using radiotracer technique

    International Nuclear Information System (INIS)

    Rajesh Kumar; Sadhana Mohan; Pant, H.J.; Sharma, V.K.; Mahajani, S.M.

    2012-01-01

    A radiotracer study was carried out in a trickle bed reactor (TBR) independently filled with two different types of packing i.e., hydrophobic and hydrophilic. The study was aimed at to estimate liquid holdup and investigate the dispersion characteristics of liquid phase with both types of packing at different operating conditions. Water and H2 gas were used as aqueous and gas phase, respectively. The liquid and gas flow rates used ranged from 0.83 x 10 -7 -16.67 x 10 -7 m 3 /s and 0-3.33 x 10 -4 m 3 (std)/s, respectively. Residence time distribution (RTD) of liquid phase was measured using 82 Br as radiotracer and about 10 MBq activity was used in each run. Mean residence time (MRT) and holdup of liquid phase were estimated from the measured RTD data. An axial dispersion with exchange model was used to simulate the measured RTD curves and model parameters (Peclet number and MRT) were obtained. At higher liquid flow rates, the TBR behaves as a plug flow reactor, whereas at lower liquid flow rates, the flow was found to be highly dispersed. The results of investigation indicated that the dispersion of liquid phase is higher in case of hydrophobic packing, whereas holdup is higher in case of hydrophilic packing. (author)

  3. Transesterification of rapeseed oil for biodiesel production in trickle-bed reactors packed with heterogeneous Ca/Al composite oxide-based alkaline catalyst.

    Science.gov (United States)

    Meng, Yong-Lu; Tian, Song-Jiang; Li, Shu-Fen; Wang, Bo-Yang; Zhang, Min-Hua

    2013-05-01

    A conventional trickle bed reactor and its modified type both packed with Ca/Al composite oxide-based alkaline catalysts were studied for biodiesel production by transesterification of rapeseed oil and methanol. The effects of the methanol usage and oil flow rate on the FAME yield were investigated under the normal pressure and methanol boiling state. The oil flow rate had a significant effect on the FAME yield for the both reactors. The modified trickle bed reactor kept over 94.5% FAME yield under 0.6 mL/min oil flow rate and 91 mL catalyst bed volume, showing a much higher conversion and operational stability than the conventional type. With the modified trickle bed reactor, both transesterification and methanol separation could be performed simultaneously, and glycerin and methyl esters were separated additionally by gravity separation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Butanol production by bioconversion of cheese whey in a continuous packed bed reactor.

    Science.gov (United States)

    Raganati, F; Olivieri, G; Procentese, A; Russo, M E; Salatino, P; Marzocchella, A

    2013-06-01

    Butanol production by Clostridium acetobutylicum DSM 792 fermentation was investigated. Unsupplemented cheese whey was adopted as renewable feedstock. The conversion was successfully carried out in a biofilm packed bed reactor (PBR) for more than 3 months. The PBR was a 4 cm ID, 16 cm high glass tube with a 8 cm bed of 3mm Tygon rings, as carriers. It was operated at the dilution rate between 0.4h(-1) and 0.94 h(-1). The cheese whey conversion process was characterized in terms of metabolites production (butanol included), lactose conversion and biofilm mass. Under optimized conditions, the performances were: butanol productivity 2.66 g/Lh, butanol concentration 4.93 g/L, butanol yield 0.26 g/g, butanol selectivity of the overall solvents production 82 wt%. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. The Performance of the Trickle Bed Reactor Packed with the Pt/SDBC Catalyst Mixture for the CECE Process

    International Nuclear Information System (INIS)

    Seungwoo Paek; Do-Hee Ahn; Heui-Joo Choi; Kwang-Rag Kim; Hongsuk Chung; Sung-Paal Yim; Minsoo Lee; Kyu-Min Song; Soon Hwan Sohn

    2006-01-01

    The CECE (Combined Electrolysis Catalytic Exchange) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE process is composed of an electrolysis cell and a LPCE (Liquid Phase Catalytic Exchange) column. This paper describes the experimental results of the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst for the development of the LPCE column of the CECE process. The hydrophobic Pt/SDBC (Styrene Divinyl Benzene Copolymer) catalyst has been developed by Korean researchers for the LPCE column of WTRF (Wolsong Tritium Removal Facility). An experimental apparatus was constructed for the various experiments with the different parameters, such as hydrogen flow rate, temperature, and the structure of the mixed catalyst column. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring). The performance of the catalyst bed was expressed as an overall rate constant Kya. To improve the performance of the trickle bed, the modification of the catalyst bed design (changing the shape of the catalyst complex and diluting with inert) has been investigated. (author)

  6. Modeling and simulation of a packed bed reactor for hydrogen by methanol steam reforming

    International Nuclear Information System (INIS)

    Aboudheir, A.; Idem, R.

    2004-01-01

    'Full text:' The performance of a catalytic packed bed tubular reactor for hydrogen production depends on mass transport characteristics and temperature distribution in the reactor. To accurately predict this performance, a rigorous numerical model has been developed based on coupled mass, energy, and momentum balance equations in cylindrical coordinates. This comprehensive model takes into account the variations of the concentration and temperature in both the axial and radial directions as well as the pressure drop along the packed reactor. Also, experimental measurements for hydrogen production were collected using a manganese-promoted co-precipitated Cu-Al catalyst for methanol-steam reforming in a micro-reactor having 10 mm i.d. and 460 mm overall length. The operating temperature ranged from 443 to 523 K and the space-time ranged from 0.1 to 2.5 kg cat h/kmol CH3OH. The simulation results were found to be in close agreement with the experimental data over the various operating conditions. This confirms the validity of both the numerical model of this work and our previous published kinetics models for this reaction system. In addition, the model formulation is applicable to handle reactions, not only for the microreactor presented in this work, but also, for other laboratory size and industrial scale processes for hydrogen production by hydrocarbon reformation. (author)

  7. Phenol degradation in an anaerobic fluidized bed reactor packed with low density support materials

    Directory of Open Access Journals (Sweden)

    G. P. Sancinetti

    2012-03-01

    Full Text Available The objective of this research was to study phenol degradation in anaerobic fluidized bed reactors (AFBR packed with polymeric particulate supports (polystyrene - PS, polyethylene terephthalate - PET, and polyvinyl chloride - PVC. The reactors were operated with a hydraulic retention time (HRT of 24 h. The influent phenol concentration in the AFBR varied from 100 to 400 mg L-1, resulting in phenol removal efficiencies of ~100%. The formation of extracellular polymeric substances yielded better results with the PVC particles; however, deformations in these particles proved detrimental to reactor operation. PS was found to be the best support for biomass attachment in an AFBR for phenol removal. The AFBR loaded with PS was operated to analyze the performance and stability for phenol removal at feed concentrations ranging from 50 to 500 mg L-1. The phenol removal efficiency ranged from 90-100%.

  8. PEBBLES: A COMPUTER CODE FOR MODELING PACKING, FLOW AND RECIRCULATIONOF PEBBLES IN A PEBBLE BED REACTOR

    Energy Technology Data Exchange (ETDEWEB)

    Joshua J. Cogliati; Abderrafi M. Ougouag

    2006-10-01

    A comprehensive, high fidelity model for pebble flow has been developed and embodied in the PEBBLES computer code. In this paper, a description of the physical artifacts included in the model is presented and some results from using the computer code for predicting the features of pebble flow and packing in a realistic pebble bed reactor design are shown. The sensitivity of models to various physical parameters is also discussed.

  9. Thermal hydraulic and neutronic interaction in the rotating bed reactor

    International Nuclear Information System (INIS)

    Lee, C.C.

    1986-01-01

    Power transient characteristics in a rotating fluidized bed reactor (RBR) are investigated theoretically. A propellant flow perturbation is assumed to occur in an initially equilibrium state of the core. Transfer functions representing quasi-one-dimensional mutual feedback between thermal hydraulics and neutronics are developed and analyzed in the frequency domain. Neutronic responses are determined by Fermi-age theory for slowing down of fast neutrons and diffusion theory for thermal neutron distribution. Neutron leakage through the exhaust nozzle is accounted for by applying diffuse view factors similar to those applied in radiative heat transfer. The bed expansion behavior is described by a kinematic wave equation derived from the continuity of the gas phase. The drift flux approach is used to determine the yield fractions in the equilibrium bed. Thermal responses of fuel are evaluated by dividing it into several volume-averaged zones to better account for the transient effects over single zone models. Sample calculations are undertaken for the various operation conditions and design parameters of the RBR based on 250 MW/sub t/, 1000 MW/sub t/, and 5000 MW/sub t/ power reactors. The results show that power transients are dependent on the parametric changes of optical thickness and view factors

  10. Performance of a pilot-scale packed bed reactor for perchlorate reduction using a sulfur oxidizing bacterial consortium.

    Science.gov (United States)

    Boles, Amber R; Conneely, Teresa; McKeever, Robert; Nixon, Paul; Nüsslein, Klaus R; Ergas, Sarina J

    2012-03-01

    A novel sulfur-utilizing perchlorate reducing bacterial consortium successfully treated perchlorate (ClO₄⁻) in prior batch and bench-scale packed bed reactor (PBR) studies. This study examined the scale up of this process for treatment of water from a ClO ₄⁻ and RDX contaminated aquifer in Cape Cod Massachusetts. A pilot-scale upflow PBR (∼250-L) was constructed with elemental sulfur and crushed oyster shell packing media. The reactor was inoculated with sulfur oxidizing ClO₄⁻ reducing cultures enriched from a wastewater seed. Sodium sulfite provided a good method of dissolved oxygen removal in batch cultures, but was found to promote the growth of bacteria that carry out sulfur disproportionation and sulfate reduction, which inhibited ClO₄⁻ reduction in the pilot system. After terminating sulfite addition, the PBR successfully removed 96% of the influent ClO₄⁻ in the groundwater at an empty bed contact time (EBCT) of 12 h (effluent ClO₄⁻ of 4.2 µg L(-1)). Simultaneous ClO₄⁻ and NO₃⁻ reduction was observed in the lower half of the reactor before reactions shifted to sulfur disproportionation and sulfate reduction. Analyses of water quality profiles were supported by molecular analysis, which showed distinct groupings of ClO₄⁻ and NO₃⁻ degrading organisms at the inlet of the PBR, while sulfur disproportionation was the primary biological process occurring in the top potion of the reactor. Copyright © 2011 Wiley Periodicals, Inc.

  11. Modeling the competitive effect of ammonium oxidizers and heterotrophs on the degradation of MTBE in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A mathematical model was used to study effects on the degradation of methyl tert-butyl ether (MTBE) in a packed bed reactor due to the presence of contaminants such as ammonium, and the mix of benzene, toluene, ethylbenzene and xylenes (BTEX). It was shown that competition between the slower...

  12. Application of a model to investigate the effective thermal conductivity of randomly packed fusion pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoliang; Zheng, Jie; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn

    2016-05-15

    In our precious study, a prediction model, which calculates the effective thermal conductivity k{sub eff} of mono-sized pebble beds, has been developed and validated. Based on this model, here the effects of these influencing factors such as pebble size, thermal radiation, contact area, filling gas, gas flow, gas pressure, etc. on the k{sub eff} of randomly packed fusion pebble beds are studied and analyzed. The pebble beds investigated include Li{sub 4}SiO{sub 4}, Li{sub 2}ZrO{sub 3}, Li{sub 2}TiO{sub 3}, Li{sub 2}O, Be and BeO pebble beds. In the current study, many important and meaningful conclusions are derived and some of them are similar to the existing research results. Particularly, some critters that under which conditions the effect of some influencing factors can be neglected or should be considered are also presented.

  13. Fluidized Bed Reactor as Solid State Fermenter

    Directory of Open Access Journals (Sweden)

    Krishnaiah, K.

    2005-01-01

    Full Text Available Various reactors such as tray, packed bed, rotating drum can be used for solid-state fermentation. In this paper the possibility of fluidized bed reactor as solid-state fermenter is considered. The design parameters, which affect the performances are identified and discussed. This information, in general can be used in the design and the development of an efficient fluidized bed solid-state fermenter. However, the objective here is to develop fluidized bed solid-state fermenter for palm kernel cake conversion into enriched animal and poultry feed.

  14. METHOD OF CALCULATION OF THE NON-STATIONARY TEMPERATURE FIELD INSIDE OF THERMAL PACKED BED ENERGY STORAGE

    Directory of Open Access Journals (Sweden)

    Ermuratschii V.V.

    2014-04-01

    Full Text Available e paper presents a method of the approximate calculation of the non-stationary temperature field inside of thermal packed bed energy storages with feasible and latent heat. Applying thermoelectric models and computational methods in electrical engineering, the task of computing non-stationary heat transfer is resolved with respect to third type boundary conditions without applying differential equations of the heat transfer. For sub-volumes of the energy storage the method is executed iteratively in spatiotemporal domain. Single-body heating is modeled for each sub-volume, and modeling conditions are assumed to be identical for remained bod-ies, located in the same sub-volume. For each iteration step the boundary conditions will be represented by re-sults at the previous step. The fulfillment of the first law of thermodynamics for system “energy storage - body” is obtained by the iterative search of the mean temperature of the energy storage. Under variable boundary con-ditions the proposed method maybe applied to calculating temperature field inside of energy storages with packed beds consisted of solid material, liquid and phase-change material. The method may also be employed to compute transient, power and performance characteristics of packed bed energy storages.

  15. Ozo-Dyes mixture degradation in a fixed bed biofilm reactor packed with volcanic porous rock

    International Nuclear Information System (INIS)

    Contreras-Blancas, E.; Cobos-Vasconcelos, D. de los; Juarez-Ramirez, C.; Poggi-Varaldo, H. M.; Ruiz-Ordaz, N.; Galindez-Mayer, J.

    2009-01-01

    Textile industries discharge great amounts of dyes and dyeing-process auxiliaries, which pollute streams and water bodies. Several dyes, especially the ones containing the azo group, can cause harmful effects to different organisms including humans. Through bacterial and mammalian tests, azo dyes or their derived aromatic amines have shown cell genotoxicity. The purpose of this work was to evaluate the effect of air flow rate on azo-dyes mixture biodegradation by a microbial community immobilized in a packed bed reactor. (Author)

  16. Ozo-Dyes mixture degradation in a fixed bed biofilm reactor packed with volcanic porous rock

    Energy Technology Data Exchange (ETDEWEB)

    Contreras-Blancas, E.; Cobos-Vasconcelos, D. de los; Juarez-Ramirez, C.; Poggi-Varaldo, H. M.; Ruiz-Ordaz, N.; Galindez-Mayer, J.

    2009-07-01

    Textile industries discharge great amounts of dyes and dyeing-process auxiliaries, which pollute streams and water bodies. Several dyes, especially the ones containing the azo group, can cause harmful effects to different organisms including humans. Through bacterial and mammalian tests, azo dyes or their derived aromatic amines have shown cell genotoxicity. The purpose of this work was to evaluate the effect of air flow rate on azo-dyes mixture biodegradation by a microbial community immobilized in a packed bed reactor. (Author)

  17. Sequential UASB and dual media packed-bed reactors for domestic wastewater treatment - experiment and simulation.

    Science.gov (United States)

    Rodríguez-Gómez, Raúl; Renman, Gunno

    2016-01-01

    A wastewater treatment system composed of an upflow anaerobic sludge blanket (UASB) reactor followed by a packed-bed reactor (PBR) filled with Sorbulite(®) and Polonite(®) filter material was tested in a laboratory bench-scale experiment. The system was operated for 50 weeks and achieved very efficient total phosphorus (P) removal (99%), 7-day biochemical oxygen demand removal (99%) and pathogenic bacteria reduction (99%). However, total nitrogen was only moderately reduced in the system (40%). A model focusing on simulation of organic material, solids and size of granules was then implemented and validated for the UASB reactor. Good agreement between the simulated and measured results demonstrated the capacity of the model to predict the behaviour of solids and chemical oxygen demand, which is critical for successful P removal and recovery in the PBR.

  18. Hydrogenation of Levulinic Acid to gamma-Valerolactone in Water Using Millimeter Sized Supported Ru Catalysts in a Packed Bed Reactor

    NARCIS (Netherlands)

    Piskun, A. S.; de Haan, J. E.; Wilbers, E.; de Bovenkamp, H. H. van; Tang, Z.; Heeres, Hero

    gamma-Valerolactone (GVL) has been identified as a sustainable platform chemical for the production of carbon-based chemicals. We here report an experimental study on the catalytic hydrogenation of levulinic acid (LA) in water to GVL in a packed bed reactor using supported Ru catalysts (carbon,

  19. Three-phase packed bed reactor with an evaporating solvent—I. Experimental: the hydrogenation of 2,4,6-trinitrotoluene in methanol

    NARCIS (Netherlands)

    van Gelder, K.B.; Damhof, J.K.; Kroijenga, P.J.; Westerterp, K.R.

    1990-01-01

    In this paper we present experimental data on the three-phase hydrogenation of 2,4,6-trinitrotoluene (TNT) to triaminotoluene. The experiments are performed in a cocurrent upflow packed bed reactor. Methanol is used as an evaporating solvent. The influence of the main operating parameters, the

  20. Process integration for biological sulfate reduction in a carbon monoxide fed packed bed reactor.

    Science.gov (United States)

    Kumar, Manoj; Sinharoy, Arindam; Pakshirajan, Kannan

    2018-05-09

    This study examined immobilized anaerobic biomass for sulfate reduction using carbon monoxide (CO) as the sole carbon source under batch and continuous fed conditions. The immobilized bacteria with beads made of 10% polyvinyl alcohol (PVA) showed best results in terms of sulfate reduction (84 ± 3.52%) and CO utilization (98 ± 1.67%). The effect of hydraulic retention time (HRT), sulfate loading rate and CO loading rate on sulfate and CO removal was investigated employing a 1L packed bed bioreactor containing the immobilized biomass. At 48, 24 and 12 h HRT, the sulfate removal was 94.42 ± 0.15%, 89.75 ± 0.47% and 61.08 ± 0.34%, respectively, along with a CO utilization of more than 90%. The analysis of variance (ANOVA) of the results obtained showed that only the initial CO concentration significantly affected the sulfate reduction process. The reactor effluent sulfate concentrations were 27.41 ± 0.44, 59.16 ± 1.08, 315.83 ± 7.33 mg/L for 250, 500 and 1000 mg/L of influent sulfate concentrations respectively, under the optimum operating conditions. The sulfate reduction rates matched well with low inlet sulfate loading rates, indicating stable performance of the bioreactor system. Overall, this study yielded very high sulfate reduction efficiency by the immobilized anaerobic biomass under high CO loading condition using the packed bed reactor system. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Intraparticle mass transport

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

  2. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Intraparticle Mass Transport

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    For partial oxidation systems, where the reaction order in oxygen of the formation rate of the target product is smaller than the reaction order in oxygen of the consecutive reaction rate toward the waste product, a packed bed membrane reactor can be applied to distributively dose oxygen along the

  3. THE EFFECT OF THE THICKNESS OF A PACKED BED ON THE DYNAMIC AND THERMAL BEHAVIOR OF A SOLAR DRYER

    Directory of Open Access Journals (Sweden)

    S KHALDI

    2015-06-01

    Full Text Available Drying food in the sun is a safe, easy and economical way to preserve food, especially fruits. Cabinet dryers are the most popular equipment for fruit drying. Because of intermittent nature of solar energy, storage is required for uninterrupted supply in order to match the needs. The main objective of this study is to assess effectiveness of continuous solar dryer integrated with packed bed as thermal storage with natural airflow for drying figs (Ficuscarica. The cabinet dryer were envisaged theoretically (computational fluid dynamics (CFD. The distribution of the velocity and temperature of air within the solar dryer were presented during one day of August and under the climate conditions of Tlemcen (Algeria.  The effects of presence of a packed bed on the distribution of velocity and temperature of airflow and on the temperature of figs were analyzed. The results show that the solar dryer design, incorporating a packed bed enhances the capabilities and performance of the solar dryer, through increasing time of drying.

  4. Optimization of lipase-catalyzed biodiesel by isopropanolysis in a continuous packed-bed reactor using response surface methodology.

    Science.gov (United States)

    Chang, Cheng; Chen, Jiann-Hwa; Chang, Chieh-Ming J; Wu, Tsung-Ta; Shieh, Chwen-Jen

    2009-10-31

    Isopropanolysis reactions were performed using triglycerides with immobilized lipase in a solvent-free environment. This study modeled the degree of isopropanolysis of soybean oil in a continuous packed-bed reactor when Novozym 435 was used as the biocatalyst. Response surface methodology (RSM) and three-level-three-factor Box-Behnken design were employed to evaluate the effects of synthesis parameters, reaction temperature ( degrees C), flow rate (mL/min) and substrate molar ratio of isopropanol to soybean oil, on the percentage molar conversion of biodiesel by transesterification. The results show that flow rate and temperature have a significant effect on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions for synthesis were as follows: flow rate 0.1 mL/min, temperature 51.5 degrees C and substrate molar ratio 1:4.14. The predicted value was 76.62+/-1.52% and actual experimental value was 75.62+/-0.81% molar conversion. Moreover, continuous enzymatic process for seven days did not show any appreciable decrease in the percent of molar conversion (75%). This work demonstrates the applicability of lipase catalysis to prepare isopropyl esters by transesterification in solvent-free system with a continuous packed-bed reactor for industrial production.

  5. Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

    Directory of Open Access Journals (Sweden)

    Marchetti Leonardo

    2006-04-01

    Full Text Available Abstract Background Olive mill wastewater (OMW is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter

  6. Anaerobic Digestion of Sugarcane Vinasse Through a Methanogenic UASB Reactor Followed by a Packed Bed Reactor.

    Science.gov (United States)

    Cabrera-Díaz, A; Pereda-Reyes, I; Oliva-Merencio, D; Lebrero, R; Zaiat, M

    2017-12-01

    The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m -3 day -1 with averages of 0.289 m 3 CH 4  kg COD r -1 for the UASB reactor and 4.4 kg COD m -3 day -1 with 0.207 m 3 CH 4  kg COD r -1 for APBR. The OLR played a major role in the emission of H 2 S conducting to relatively stable quality of biogas emitted from the APBR, with H 2 S concentrations <10 mg L -1 . The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH 4 and a lower H 2 S content in biogas.

  7. Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies

    OpenAIRE

    Vadgama, Rajeshkumar N.; Odaneth, Annamma A.; Lali, Arvind M.

    2015-01-01

    Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B fr...

  8. Numerical simulation and experimental verification of gas flow through packed beds

    International Nuclear Information System (INIS)

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

    2003-01-01

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

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

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

    International Nuclear Information System (INIS)

    Bemansour, A.

    2006-01-01

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

  11. Packed- and fluidized-bed biofilm reactor performance for anaerobic wastewater treatment.

    Science.gov (United States)

    Denac, M; Dunn, I J

    1988-07-05

    Anaerobic degradation performance of a laboratory-scale packed-bed reactor (PBR) was compared with two fluidized-bed biofilm reactors (FBRs) on molasses and whey feeds. The reactors were operated under constant pH (7) and temperature (35 degrees C) conditions and were well mixed with high recirculation rates. The measured variables were chemical oxygen demand (COD), individual organic acids, gas composition, and gas rates. As carrier, sand of 0.3-0.5 mm diameter was used in the FBR, and porous clay spheres of 6 mm diameter were used in the PBR. Startup of the PBR was achieved with 1-5 day residence times. Start-up of the FBR was only successful if liquid residence times were held low at 2-3 h. COD degradations of 86% with molasses (90% was biodegradable) were reached in both the FBR and PBR at 6 h residence time and loadings of 10 g COD/L day. At higher loadings the FBR gave the best performance; even at 40-45 g COD/L day, with 6 h residence times, 70% COD was degraded. The PBR could not be operated above 20 g COD/L day without clogging. A comparison of the reaction rates show that the PBR and FBR per formed similarly at low concentrations in the reactors up to 1 g COD/L, while above 3 g COD/L the rates were 17.4 g COD/L day for the PBR and 38.4 g COD/L day for the FBR. This difference is probably due to diffusion limitations and a less active biomass content of the PBR compared with the fluidized bed.The results of dynamic step change experiments, in which residence times and feed concentrations were changed hanged at constant loading, demonstrated the rapid response of the reactors. Thus, the response times for an increase in gas rate or an increase in organic acids due to an increase in feed concentration were less than 1 day and could be explained by substrate limitation. Other slower responses were observed in which the reactor culture adapted over periods of 5-10 days; these were apparently growth related. An increase in loading of over 100% always resulted

  12. Fungi solubilisation of low rank coal: performances of stirred tank, fluidised bed and packed bed reactors

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-02-01

    Full Text Available Coal biosolubilisation was investigated in stirred tank reactor, fluidised bed and fixed bed bioreactors with a view to highlight the advantages and shortcomings of each of these reactor configurations. The stirred aerated bioreactor and fluidised...

  13. A comparison between CFD simulation and experimental investigation of a packed-bed thermal energy storage system

    International Nuclear Information System (INIS)

    Cascetta, Mario; Cau, Giorgio; Puddu, Pierpaolo; Serra, Fabio

    2016-01-01

    Highlights: • Thermocline formation inside a sensible type packed bed during a complete cycle. • Thermal properties of both phases must be temperature-dependent in the simulation. • Bed porosity increases from the center to the container wall. • Thermal dispersion and solid conduction must be considered in the model. • The wall influences the radial temperature profile and the amount of energy stored. - Abstract: This work presents the comparison between CFD and experimental results obtained on a sensible thermal energy storage system based on alumina beads freely poured into a carbon steel tank. Experimental investigations of charging and discharging phases were carried out at a constant mass flow rate using air as heat transfer fluid. The experimental set-up was instrumented with several thermocouples to detect axial and radial temperature distribution as well as reservoir wall temperature. The experimental results were compared with those obtained from CFD simulations carried out with the FLUENT software. The computational domain consists of an axisymmetric tank of cylindrical shape filled with a porous bed coupled with the wall. The governing equations are solved for incompressible turbulent flow and fully developed forced convection, based on the two-phase transient model equation (LTNE-local thermal non-equilibrium) to calculate the temperature of fluid and solid phases. The porosity of the bed is considered variable in the radial direction, while the thermodynamic properties of both phases are temperature-dependent. The influence of the thermal dispersion within the porous bed, as well as the effective conductivity between the beads was considered. The heat transfer coefficient was calculated according to correlation for forced convection within porous media. Numerical results show a good agreement with experimental ones if thermal properties are considered temperature-dependent and the experimental temperature profile at the inlet of the bed is

  14. A CFD model for biomass combustion in a packed bed furnace

    Energy Technology Data Exchange (ETDEWEB)

    Karim, Md. Rezwanul [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia); Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Ovi, Ifat Rabbil Qudrat [Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Naser, Jamal, E-mail: jnaser@swin.edu.au [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia)

    2016-07-12

    Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.

  15. Thermofluid-neutronic stability of the rotating, fluidized bed, space-power reactor

    International Nuclear Information System (INIS)

    Lee, C.C.; Jones, O.C.; Becker, M.

    1993-01-01

    A rotating fluidized bed nuclear reactor has the potential of being a vary attractive option for ultra-high power space systems, especially for propulsion. Research has already examined fuel bed expansion due to variations in state variables, propellant flow rate, and rotational speed, and has also considered problems related to thermal stress. This paper describes the results of a coupled thermofluid-neutronic analysis where perturbations in fuel bed height caused by maneuvering changes in operating conditions alter power levels due to varying absorption of neutrons which would otherwise leak from the system, mainly through the nozzle. This first analysis was not a detailed stability analysis. Rather, it utilized simplified neutronic methods, and was intended to provide an order-of-magnitude assessment of the stability of the reactor with the intention to determine whether or not stability might be a 'concept killer'. Stability was compared with a fixed-fuel-bed reactor of identical geometry for three different cases comprising a set of small, medium and large sizes/powers from 250 MW to 5 GW. It was found that power fluctuations in the fluidized bed reactor were larger by 100 db or more than expected in a packed bed reactor of the same geometry, but never resulted in power excursions. Margins to unit gain in some cases, however, were sufficiently small that the approximations in this quasi-2-dimensional model may not be sufficiently accurate to preclude significant excursions. (orig.)

  16. Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

    Science.gov (United States)

    Rahman, N K; Kamaruddin, A H; Uzir, M H

    2011-08-01

    The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

  17. Continuous Packed Bed Reactor with Immobilized β-Galactosidase for Production of Galactooligosaccharides (GOS

    Directory of Open Access Journals (Sweden)

    Barbara Rodriguez-Colinas

    2016-11-01

    Full Text Available The β-galactosidase from Bacillus circulans was covalently attached to aldehyde-activated (glyoxal agarose beads and assayed for the continuous production of galactooligosaccharides (GOS in a packed-bed reactor (PBR. The immobilization was fast (1 h and the activity of the resulting biocatalyst was 97.4 U/g measured with o-nitrophenyl-β-d-galactopyranoside (ONPG. The biocatalyst showed excellent operational stability in 14 successive 20 min reaction cycles at 45 °C in a batch reactor. A continuous process for GOS synthesis was operated for 213 h at 0.2 mL/min and 45 °C using 100 g/L of lactose as a feed solution. The efficiency of the PBR slightly decreased with time; however, the maximum GOS concentration (24.2 g/L was obtained after 48 h of operation, which corresponded to 48.6% lactose conversion and thus to maximum transgalactosylation activity. HPAEC-PAD analysis showed that the two major GOS were the trisaccharide Gal-β(1→4-Gal-β(1→4-Glc and the tetrasaccharide Gal-β(1→4-Gal-β(1→4-Gal-β(1→4-Glc. The PBR was also assessed in the production of GOS from milk as a feed solution. The stability of the bioreactor was satisfactory during the first 8 h of operation; after that, a decrease in the flow rate was observed, probably due to partial clogging of the column. This work represents a step forward in the continuous production of GOS employing fixed-bed reactors with immobilized β-galactosidases.

  18. An in situ spatially resolved analytical technique to simultaneously probe gas phase reactions and temperature within the packed bed of a plug flow reactor.

    Science.gov (United States)

    Touitou, Jamal; Burch, Robbie; Hardacre, Christopher; McManus, Colin; Morgan, Kevin; Sá, Jacinto; Goguet, Alexandre

    2013-05-21

    This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. As an exemplar, we have examined a heterogeneously catalysed gas phase reaction within the bed of a powdered oxide supported metal catalyst. The design of the gas sampling and the temperature recording systems are disclosed. A stationary capillary with holes drilled in its wall and a moveable reactor coupled with a mass spectrometer are used to enable sampling and analysis. This method has been designed to limit the invasiveness of the probe on the reactor by using the smallest combination of thermocouple and capillary which can be employed practically. An 80 μm (O.D.) thermocouple has been inserted in a 250 μm (O.D.) capillary. The thermocouple is aligned with the sampling holes to enable both the gas composition and temperature profiles to be simultaneously measured at equivalent spatially resolved positions. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst and the spatial resolution profiles of chemical species concentrations and temperature as a function of the axial position within the catalyst bed are reported.

  19. Propagation of negative electrical discharges through 2-dimensional packed bed reactors

    International Nuclear Information System (INIS)

    Kruszelnicki, Juliusz; Engeling, Kenneth W; Foster, John E; Xiong, Zhongmin; Kushner, Mark J

    2017-01-01

    Plasma-based pollutant remediation and value-added gas production have recently gained increased attention as possible alternatives to the currently-deployed chemical reactor systems. Electrical discharges in packed bed reactors (PBRs) are of interest, due to their ability to synergistically combine catalytic and plasma chemical processes. In principle, these systems could be tuned to produce specific products, based on their application by combinations of power formats, materials, geometries and working gases. Negative voltage, atmospheric-pressure plasma discharges sustained in humid air in a PBR-like geometry were experimentally characterized using ICCD imaging and simulated in 2-dimensions (2D) to provide insights into possible routes to this tunability. Surface ionization waves (SIWs) and positive restrikes through the lattice of dielectric rods were shown to be the principal means of producing reactive species. The number and intensity of SIWs and restrikes are sensitive functions of the alignment of the lattice of dielectric beads (or rods in 2D) with respect to the applied electric field. Decreased spacing between the dielectric elements leads to an increased electric field enhancement in the gas, and therefore locally higher plasma densities, but does not necessarily impact the types of discharges that occur through the lattice. (paper)

  20. Propagation of negative electrical discharges through 2-dimensional packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Xiong, Zhongmin; Kushner, Mark J.

    2017-01-01

    Plasma-based pollutant remediation and value-added gas production have recently gained increased attention as possible alternatives to the currently-deployed chemical reactor systems. Electrical discharges in packed bed reactors (PBRs) are of interest, due to their ability to synergistically combine catalytic and plasma chemical processes. In principle, these systems could be tuned to produce specific products, based on their application by combinations of power formats, materials, geometries and working gases. Negative voltage, atmospheric-pressure plasma discharges sustained in humid air in a PBR-like geometry were experimentally characterized using ICCD imaging and simulated in 2-dimensions (2D) to provide insights into possible routes to this tunability. Surface ionization waves (SIWs) and positive restrikes through the lattice of dielectric rods were shown to be the principal means of producing reactive species. The number and intensity of SIWs and restrikes are sensitive functions of the alignment of the lattice of dielectric beads (or rods in 2D) with respect to the applied electric field. Decreased spacing between the dielectric elements leads to an increased electric field enhancement in the gas, and therefore locally higher plasma densities, but does not necessarily impact the types of discharges that occur through the lattice.

  1. Phenols removal using ozonation-adsorption with granular activated carbon (GAC) in rotating packed bed reactor

    Science.gov (United States)

    Karamah, E. F.; Leonita, S.; Bismo, S.

    2018-01-01

    Synthetic wastewater containing phenols was treated using combination method of ozonation-adsorption with GAC (Granular Activated Carbon) in a packed bed rotating reactor. Ozone reacts quickly with phenol and activated carbon increases the oxidation process by producing hydroxyl radicals. Performance parameters evaluated are phenol removal percentage, the quantity of hydroxyl radical formed, changes in pH and ozone utilization, dissolved ozone concentration and ozone concentration in off gas. The performance of the combination method was compared with single ozonation and single adsorption. The influence of GAC dose and initial pH of phenols were evaluated in ozonation-adsorption method. The results show that ozonation-adsorption method generates more OH radicals than a single ozonation. Quantity of OH radical formation increases with increasing pH and quantity of the GAC. The combination method prove better performance in removing phenols. At the same operation condition, ozonation-adsorption method is capable of removing of 78.62% phenols as compared with single ozonation (53.15%) and single adsorption (36.67%). The increasing percentage of phenol removal in ozonation-adsorption method is proportional to the addition of GAC dose, solution pH, and packed bed rotator speed. Maximum percentage of phenol removal is obtained under alkaline conditions (pH 10) and 125 g of GAC

  2. FBR and RBR particle bed space reactors

    International Nuclear Information System (INIS)

    Powell, J.R.; Botts, T.E.

    1983-01-01

    Compact, high-performance nuclear reactor designs based on High-Temperature Gas Reactors (HTGRs) particulate fuel are investigated. The large surface area available with the small-diameter (approx. 500 microns) particulate fuel allows very high power densities (MW's/liter), small temperature differences between fuel and coolant (approx. 10 0 K), high coolant-outlet temperatures (1500 to 3000 0 K, depending on design), and fast reactor startup (approx. 2 to 3 seconds). Two reactor concepts are developed - the Fixed Bed Reactor (FBR), where the fuel particles are packed into a thin annular bed between two porous cylindrical drums, and the Rotating Bed Reactor (RBR), where the fuel particles are held inside a cold rotating (typically approx. 500 rpm) porous cylindrical drum. The FBR can operate steady-state in the closed-cycle He-cooled mode or in the open-cycle H 2 -cooled mode. The RBR will operate only in the open-cycle H 2 -cooled mode

  3. Thermal conductivity model of vibro-packed fuel

    International Nuclear Information System (INIS)

    Yeon Soo, Kim

    2001-01-01

    In an effort to dispose of excess weapons grade plutonium accumulated in the cold war era in the United States and the Russian Federation, one method currently under investigation is the conversion of the plutonium into mixed oxide (MOX) reactor fuel for LWRs and fast reactors in the Russian Federation. A fuel option already partly developed at the Research Institute of Atomic Reactors (RIAR) in Dimitrovgrad is that of vibro-packed MOX. Fuel rod fabrication using powder vibro-packing is attractive because it includes neither a process too complex to operate in glove boxes (or remotely), nor a waste-producing step necessary for the conventional pellet rod fabrication. However, because of its loose bonding between fuel particles at the beginning of life, vibro-packed MOX fuel has a somewhat less effective thermal conductivity than fully sintered pellet fuel, and undergoes more restructuring. Helium would also likely be pressurized in vibro-packed MOX fuel rods for LWRs to enhance initial fuel thermal conductivity. The combination of these two factors complicates development of an accurate thermal conductivity model. But clearly in order to predict fuel thermomechanical responses during irradiation of vibro-packed MOX fuel, fuel thermal conductivity must be known. The Vibropac fuel of interest in this study refers the fuel that is compacted with irregular fragments of mixed oxide fuel. In this paper, the thermal-conductivity models in the literature that dealt with relatively similar situations to the present case are examined. Then, the best model is selected based on accuracy of prediction and applicability. Then, the selected model is expanded to fit the various situations of interest. (author)

  4. Applying chemical engineering concepts to non-thermal plasma reactors

    Science.gov (United States)

    Pedro AFFONSO, NOBREGA; Alain, GAUNAND; Vandad, ROHANI; François, CAUNEAU; Laurent, FULCHERI

    2018-06-01

    Process scale-up remains a considerable challenge for environmental applications of non-thermal plasmas. Undersanding the impact of reactor hydrodynamics in the performance of the process is a key step to overcome this challenge. In this work, we apply chemical engineering concepts to analyse the impact that different non-thermal plasma reactor configurations and regimes, such as laminar or plug flow, may have on the reactor performance. We do this in the particular context of the removal of pollutants by non-thermal plasmas, for which a simplified model is available. We generalise this model to different reactor configurations and, under certain hypotheses, we show that a reactor in the laminar regime may have a behaviour significantly different from one in the plug flow regime, often assumed in the non-thermal plasma literature. On the other hand, we show that a packed-bed reactor behaves very similarly to one in the plug flow regime. Beyond those results, the reader will find in this work a quick introduction to chemical reaction engineering concepts.

  5. Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma.

    Science.gov (United States)

    Liang, Wenjun; Li, Jian; Li, Jie; Jin, Yuquan

    2009-10-30

    Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO3 reactor had the highest toluene removal efficiency among the reactors. For NaNO2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

  6. Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma

    International Nuclear Information System (INIS)

    Liang Wenjun; Li Jian; Li Jie; Jin Yuquan

    2009-01-01

    Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO 3 reactor had the highest toluene removal efficiency among the reactors. For NaNO 2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

  7. A packed bed membrane reactor for the oxidative dehydrogenation of propane on a Ga2O3 / MoO3 based catalyst

    NARCIS (Netherlands)

    Kotanjac, Ž.S.; Sint Annaland, van M.; Kuipers, J.A.M.

    2010-01-01

    Oxidative dehydrogenation of propane has been studied over a Ga2O3/MoO3 based catalyst. Using a differentially operated packed bed reactor with premixed oxygen and propane feed, the kinetic parameters for the main reaction and the consecutive and parallel reactions were experimentally determined. It

  8. Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass.

    Science.gov (United States)

    Laurenzis, A; Heits, H; Wübker, S; Heinze, U; Friedrich, C; Werner, U

    1998-02-20

    A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m3pb). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m-3pb h-1 at a load of 150 g of toluene m-3pb h-1. Such a removal rate with a trickle-bed reactor was not reported before. Copyright 1998 John Wiley & Sons, Inc.

  9. Treatment of azo dye-containing wastewater by a Fenton-like process in a continuous packed-bed reactor filled with activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Isabel; Matos, Luis C. [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Duarte, Filipa [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal); Maldonado-Hodar, F.J. [Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva, 18071 Granada (Spain); Mendes, Adelio [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal); Madeira, Luis M., E-mail: mmadeira@fe.up.pt [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer Oxidation with the Fenton's reagent was carried out in a packed-bed reactor. Black-Right-Pointing-Pointer The packed-bed was filled with iron-impregnated activated carbon. Black-Right-Pointing-Pointer The increment of temperature increases the Chicago Sky Blue removal and mineralization. Black-Right-Pointing-Pointer The values of iron leaching were below 0.4 ppm in the outlet effluent. Black-Right-Pointing-Pointer It was possible to reach a dye conversion of 88% in steady-state. - Abstract: In this work, oxidation with a Fenton-like process of a dye solution was carried out in a packed-bed reactor. Activated carbon Norit RX 3 Extra was impregnated with ferrous sulfate and used as catalyst (7 wt.% of iron). The effect of the main operating conditions in the Chicago Sky Blue (CSB) degradation was analyzed. It was found that the increase in temperature leads to a higher removal of the dye and an increased mineralization. However, it also increases the iron leaching, but the values observed were below 0.4 ppm (thus, far below European Union limits). It was possible to reach, at steady-state, a dye conversion of 88%, with a total organic carbon (TOC) removal of ca. 47%, being the reactor operated at 50 Degree-Sign C, pH 3, W{sub cat}/Q = 4.1 g min mL{sup -1} (W{sub cat} is the mass of catalyst and Q the total feed flow rate) and a H{sub 2}O{sub 2} feed concentration of 2.25 mM (for a CSB feed concentration of 0.012 mM). The same performance was reached in three consecutive cycles.

  10. Properties Influencing Plasma Discharges in Packed Bed Reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for CO2 removal and conversion of waste gases into higher value compounds. We report on results of a computational investigation of PBR-DBD properties using the plasma hydrodynamics simulator nonPDPSIM with a comparison to experiments. Dielectric beads (rods in 2D) were inserted between two coplanar electrodes, 1 cm apart filled by humid air. A step-pulse of -30 kV was applied to the top electrode. Material properties of the beads (dielectric constant, secondary emission coefficient) and gas properties (photoionization and photo-absorption cross-sections, temperature) were varied. We found that photoionization plays a critical role in the propagation of the discharge through the PBR, as it serves to seed charges in regions of high electric field. Increasing rates of photo-ionization enable increases in the discharge propagation velocity, ionization rates and production of radicals. A transition between DBD-like and arc-like discharges occurs as the radiation mean free path decreases. Increasing the dielectric constant of the beads increased electric fields in the gas, which translated to increased discharge propagation velocity and charge density until ɛ/ɛ0 100. Secondary electron emission coefficient and gas temperature have minimal impacts on the discharge propagation though the latter did affect the production of reactive species. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  11. High power density reactors based on direct cooled particle beds

    Science.gov (United States)

    Powell, J. R.; Horn, F. L.

    Reactors based on direct cooled High Temperature Gas Cooled Reactor (HTGR) type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out along the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBRs) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed.

  12. Improved thermostable polyvinyl alcohol electrospun nanofibers with entangled naringinase used in a novel mini-packed bed reactor.

    Science.gov (United States)

    Nunes, Mário A P; Martins, Samuel; Rosa, M Emilia; Gois, Pedro M P; Fernandes, Pedro C B; Ribeiro, Maria H L

    2016-08-01

    Polyvinyl alcohol (PVA) electrospun nanofibers were produced using an electrospinning technique. Key parameters (e.g. collectors, distance from needle tip to collector, among others) that influence the structure and morphology of fibers were optimized. The naringinase entrapped in PVA nanofibers retained over 100% of its initial activity after 212h of operation, at 25°C. Chemical crosslinking with several boronic acids further increased the hydrolysis temperature (up to 85°C) and yielded nanofibers with thermal stability up to 121°C. A mini packed bed reactor (PBR) developed to establish the feasibility for continuous enzymatic operation, ran for 16days at 45°C. Highest naringenin biosynthesis was attained at a flow rate of 10mLh(-1). Highest volumetric (78molL(-1)h(-1)) and specific (26molh(-1)genzyme(-1)) productivities were attained at 30mLh(-1). The activity of NGase in electrospun nanofibers remained constant for almost 16days of operation at 10mLh(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. 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.)

  14. A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

    Directory of Open Access Journals (Sweden)

    Andrew Bogdan

    2009-04-01

    Full Text Available We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity.

  15. Biodegradation of p-nitrophenol using Arthrobacter chlorophenolicus A6 in a novel upflow packed bed reactor

    International Nuclear Information System (INIS)

    Sahoo, Naresh Kumar; Pakshirajan, Kannan; Ghosh, Pranab Kumar

    2011-01-01

    A novel packed bed reactor (PBR) was designed with cross flow aeration at multiple ports along the depth to improve the hydrodynamic conditions of the reactor, and the biodegradation efficiency of Arthrobacter chlorophenolicus A6 on p-nitrophenol (PNP) removal in PBR at different PNP loading rates were evaluated. The novel PBR was designed to improve the hydrodynamic features such as mixing time profile (t m95 ), oxygen mass transfer coefficient (k L a), and overall gas hold up capacity (ε G ) of the reactor. PNP concentration in the influent was varied between 600 and 1400 mg l -1 whereas the hydraulic retention time (HRT) in the reactor was varied between 18 and 7.5 h. Complete removal of PNP was achieved in the reactor up to a PNP loading rate of 2787 mg l -1 d -1 . More than 99.9% removal of PNP was achieved in the reactor for an influent concentration of 1400 mg l -1 and at 18 h HRT. In the present study, PNP was utilized as sole source of carbon and energy by A. chlorophenolicus A6. Furthermore, the bioreactor showed good compatibility in handling shock loading of PNP.

  16. Mass transfer controlled reactions in packed beds at low Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Fedkiw, P.S.

    1978-12-01

    The a priori prediction and correlation of mass-transfer rates in transport limited, packed-bed reactors at low Reynolds numbers is examined. The solutions to the governing equations for a flow-through porous electrode reactor indicate that these devices must operate at a low space velocity to suppress a large ohmic potential drop. Packed-bed data for the mass-transfer rate at such low Reynolds numbers were examined and found to be sparse, especially in liquid systems. Prior models to simulate the solid-void structure in a bed are reviewed. Here the bed was envisioned as an array of sinusoidal periodically constricted tubes (PCT). Use of this model has not appeared in the literature. The velocity field in such a tube should be a good approximation to the converging-diverging character of the velocity field in an actual bed. The creeping flow velocity profiles were calculated. These results were used in the convective-diffusion equation to find mass transfer rates at high Peclet number for both deep and shallow beds, for low Peclet numbers in a deep bed. All calculations assumed that the reactant concentration at the tube surface is zero. Mass-transfer data were experimentally taken in a transport controlled, flow-through porous electrode to test the theoretical calculations and to provide data resently unavailable for deeper beds. It was found that the sinusoidal PCT model could not fit the data of this work or that available in the literature. However, all data could be adequately described by a model which incorporates a channelingeffect. The bed was successfully modeled as an array of dual sized straight tubes.

  17. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  18. Pellet bed reactor for nuclear thermal propelled vehicles

    International Nuclear Information System (INIS)

    El-Genk, M.; Morley, N.J.; Haloulakos, V.E.

    1991-01-01

    The Pellet Bed Reactor (PeBR) concept is capable of operating at a high power density of up to 3.0 kWt/cu cm and an exit hydrogen gas temperature of 3000 K. The nominal reactor thermal power is 1500 MW and the reactor core is 0.80 m in diameter and 1.3 m high. The nominal PeBR engine generates a thrust of approximately 315 kN at a specific impulse of 1000 s for a mission duration to Mars of 250 days requiring a total firing time of 170 minutes. Because of its low diameter-to-height ratio, PeBR has enough surface area for passive removal of the decay heat from the reactor core. The reactor is equipped with two independent shutdown mechanisms; 8-B4C safety rods and 26 BeO/B4C control drums; each system is capable of operating and scraming the reactor safely. Due to the absence of core internal support structures, the PeBR can be fueled and refueled in orbit using the vacuum of space. These unique features of the PeBR provide for safety during launch, simplicity of handling, deployment, and end-of-life disposal, and vehicle extended lifetime. 11 refs

  19. Kinetics of pyridine degradation along with toluene and methylene chloride with Bacillus sp. in packed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Uma, B.; Sandhya, S. [National Environmental Engineering Research Institute, CSIR-Complex, Madras (India)

    1998-04-01

    Bacillus coagulans strain isolated from contaminated soil was immobilised on activated carbon for degradation of pyridine, toluene and methylene chloride containing synthetic wastewaters. Pyridine was supplied as the only source of nitrogen in the wastewaters. Continuous runs in a packed bed laboratory reactor showed that immobilized B. coagulans can degrade pyridine along with other organics rapidly and the effluent ammonia is also controlled in presence of ``organic carbon``. About 644 mg/l of influent TOC was efficiently degraded (82.85%) at 64.05 mg/l/hr loading. (orig.) With 2 figs., 4 tabs., 15 refs.

  20. CLC in packed beds using syngas and CuO/Al2O3: model description and experimental validation

    NARCIS (Netherlands)

    Hamers, H.P.; Gallucci, F.; Cobden, P.D.; Kimball, E.; Sint Annaland, M. van

    2014-01-01

    The objective of this work is to study the performance of the oxygen carrier in a packed bed with periodic switching between oxidizing and reducing conditions. In this paper the performance of CuO/Al2O3 as the oxygen carrier in a packed bed reactor with syngas as the fuel are investigated, while

  1. Forced Convection Heat Transfer of a sphere in Packed Bed Arrangement

    International Nuclear Information System (INIS)

    Lee, Dong-Young; Chung, Bum-Jin

    2016-01-01

    This paper analysis and discuss the forced convective heat transfer from heated single sphere, which is buried in unheated packed bed, depending on Re d with porosity. The present work determines the test matrix for the packed bed experiment. And this study discuss difference of heat transfer according to the location of heated sphere and compared heated bed with heated sphere in packed bed and compared FCC (Face Centered Cubic), HCP (Hexagonal Closed Packed) structured packed bed with random packed. This paper is to discuss and make the plan to experiment the heat transfer for depending on location of heated single sphere in unheated packed bed, to compare single sphere in packed bed with heated packed bed and to compare the structured packed bed with random packed bed. The Nu d increase as heated single sphere is close to the wall and bottom because of increasing porosity and enhancing eddy motion respectively. The existing experiment of heated sphere in packed bed do not consider the preheating effect which decrease heat transfer on downstream. The heat transfer rate of structured packed bed is different from random packed bed because of unsteady flow in random packed bed. In this study, mass transfer experiments will replace heat transfer experiments based on analogy concept. An electroplating system is adopted using limiting current technique

  2. Forced Convection Heat Transfer of a sphere in Packed Bed Arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong-Young; Chung, Bum-Jin [Kyung Hee University, Yongin (Korea, Republic of)

    2016-10-15

    This paper analysis and discuss the forced convective heat transfer from heated single sphere, which is buried in unheated packed bed, depending on Re{sub d} with porosity. The present work determines the test matrix for the packed bed experiment. And this study discuss difference of heat transfer according to the location of heated sphere and compared heated bed with heated sphere in packed bed and compared FCC (Face Centered Cubic), HCP (Hexagonal Closed Packed) structured packed bed with random packed. This paper is to discuss and make the plan to experiment the heat transfer for depending on location of heated single sphere in unheated packed bed, to compare single sphere in packed bed with heated packed bed and to compare the structured packed bed with random packed bed. The Nu{sub d} increase as heated single sphere is close to the wall and bottom because of increasing porosity and enhancing eddy motion respectively. The existing experiment of heated sphere in packed bed do not consider the preheating effect which decrease heat transfer on downstream. The heat transfer rate of structured packed bed is different from random packed bed because of unsteady flow in random packed bed. In this study, mass transfer experiments will replace heat transfer experiments based on analogy concept. An electroplating system is adopted using limiting current technique.

  3. Measurement of thermal expansion for a Li2TiO3 pebble bed

    International Nuclear Information System (INIS)

    Hisashi Tanigawa; Mikio Enoeda; Masato Akiba

    2006-01-01

    In the current design of the blanket with ceramic breeders, pebbles of breeding materials are packed into a container and used as a pebble bed. Thermal and mechanical conditions externally loaded on the bed affect thermal and mechanical properties of the bed. It is necessary to analyze thermo-mechanical properties of the bed under controlled thermal and mechanical conditions. In the present paper, thermal expansion of a Li 2 TiO 3 pebble bed was investigated. Our apparatus consists of a tensile test-apparatus and a measurement chamber. Pebbles of Li 2 TiO 3 with 2 mm diameter were used. They were packed into a container made of alumina. At first, thermal expansion of the apparatus was calibrated because the measured deformation included thermal expansions of the load rods and the container. Instead of the pebble bed, a column made of copper was installed and thermal expansion of the system was measured for the calibration. Taking into account the estimated thermal expansion of the column, thermal expansion of the rods and the container could be analyzed. Based on the correction, thermal expansion of the pebble bed was measured under compression of 0.1 MPa. Temperature of the bed was regulated from room temperature to 973 K. From the measured expansion of the bed, average thermal expansion coefficient was estimated. For the beds with different packing factors ranging from 65.5 to 68.5 %, thermal expansion coefficients were 1.4 ± 0. 10-5 K -1 . In the first measurement of the beds without pre-loading, expansion coefficients were larger for the cooling process than heating. When the beds were successively heated and cooled, the difference decreased. This means that relocation of the pebbles arises in the first heat treatment and progress of compaction is larger in the cooling process than heating. After a few heat treatments, packing states of the beds reach stable and expansion coefficients for both heat and cooling processes are close. In the case of the beds that

  4. Synthesis of Biodiesel in Batch and Packed-Bed Reactors Using Powdered and Granular Sugar Catalyst

    Science.gov (United States)

    Janaun, J.; Lim, P. M.; Balan, W. S.; Yaser, A. Z.; Chong, K. P.

    2017-06-01

    Increasing world production of palm oil warrants effective utilization of its waste. In particular, conversion of waste cooking oil into biodiesel has obtained global interest because of renewable energy need and reduction of CO2 emission. In this study, oleic acid used as a model compound for waste cooking oil conversion using esterification reaction catalysed by sugar catalyst (SC) in powdered (P-SC) and granular (G-SC) forms. The catalysts were synthesized via incomplete carbonization of D-glucose followed by functionalization with concentrated sulphuric acid. Catalysts characterizations were done for their physical and chemical properties using modern tools. Batch and packed-bed reactor systems were used to evaluate the reactivity of the catalysts. The results showed that G-SC had slightly higher total acidity and more porous than P-SC. The experimental conditions for batch reaction were temperature of 60°C, molar ratio of 1:20 (Oleic Acid:Methanol) and 2 wt. catalyst with respect to oleic acid. The results showed the maximum oleic acid conversion using G-SC and P-SC were 52 and 48, respectively. Whereas, the continuous reaction with varying feed flow rate as a function of retention time was studied by using 3 g of P-SC in 60 °C and 1:20 molar ratio in a packed-bed reactor. The results showed that a longer retention time which was 6.48 min and feed flow rate 1.38 ml/min, achieved higher average conversion of 9.9 and decreased with further increasing flow rate. G-SC showed a better average conversion of 10.8 at lowest feed flow rate of 1.38 ml/min in continuous reaction experiments. In a broader perspective, large scale continuous biodiesel production is feasible using granular over powdered catalyst mainly due to it lower pressure drop.

  5. Rice Husk Packed Bed Column Reactor To Remove Cadmium From Landfill Leachate

    Directory of Open Access Journals (Sweden)

    Monik Kasman

    2014-06-01

    Full Text Available The landfill leachate can be a major problem due to large variability of high organic, inorganic, heavy metal content and toxicity characteristics from landfill leachate such as  cadmium. Thus, this study was aimed to observe the application of rice husk packed bed column to reduce cadmium from landfill leachate. Experiment was conducted in gravity down flow system by pumping landfill leachate into packed bed column. The effect of influent flow rate to adsorption capacity was studied by varying flow rate (5 mL/min and 10 mL/min. The effluent-influent concentration ratio Ce/C0 (% as a function of throughput volume (L was used to represent the breakthrough curve in column systems. Result shows that the flow rate of 5 mL/min was favorable to achieve higher removal rates with the percentage of cadmium was 57 %. At breakthrough time, the cadmium effluent concentration reached on 0.01 mg/l for both of flow rate.ABSTRAKLindi yang dihasilkan dari TPA (Tempat Pembuangan Akhir menimbulkan permasalahan lingkungan karena kandungan pencemarnya meliputi material organik, material anorganik, logam dan material beracun. Salah satu logam berat yang terdapat dalam lindi tersebut adalah kadmium. Penelitian ini bertujuan untuk mereduksi kadmium dalam lindi dengan menggunakan sekam padi yang diinstal dalam packed bed column. Lindi dipompakan dari tangki penampung lindi ke dalam packed bed column dan dialirkan dari atas ke bawah kolom secara gravitasi. Fokus pada penelitian ini adalah pengaruh laju alir influen terhadap kapasitas adsorpsi. Dimana lindi dialirkan dengan laju alir 5 mL/menit dan 10 mL/menit. Kurva breakthrough (titik jenuh kolom dipresentasikan oleh hubungan antara rasio konsentrasi efluen-influen Ce/C0 (% dan jumlah aliran lindi yang diolah dalam kolom. Hasil eksperimen menunjukkan bahwa persentase reduksi tertinggi dicapai pada laju alir 5 mL/menit yaitu 57%. Waktu jenuh kedua laju alir (5 mL/menit dan 10 mL/menit tercapai saat konsentrasi efluen

  6. Experimental study of gas–liquid two-phase flow through packed bed under natural circulation conditions

    International Nuclear Information System (INIS)

    Chen, Shao-Wen; Miwa, Shuichiro; Griffiths, Matt

    2016-01-01

    Dry-out phenomena in packed beds or porous media may cause a significant digression of cooling/reaction performance in heat transfer/chemical reactor systems. One of the phenomena responsible for the dry-out in packed beds is known as the counter-current flow limitation (CCFL). In order to investigate the CCFL phenomena induced by gas–liquid two-phase flow in packed beds inside a pool, a natural circulation packed bed test facility was designed and constructed. A total of 27 experimental conditions covering various packing media sizes (sphere diameters: 3.0, 6.4 and 9.5 mm), packed bed heights (15, 35 and 50 cm) and water level heights (1.0, 1.5 and 2.0 m) were tested to examine the CCFL criteria with adiabatic air–water two-phase flow under natural circulation conditions. Both CCFL and flow reversal phenomena were observed, and the experimental data including instantaneous and time-averaged void fraction, differential pressure and superficial gas–liquid velocities were collected. The CCFL criteria were determined when periodical oscillations of void fraction and differential pressure appear. In addition, the Wallis correlation for CCFL was utilized for data analysis, and the Wallis coefficient, C, was determined experimentally from the packed bed CCFL tests. Compared to the existing data-sets in literature, the higher C values obtained in the present experiment suggest a possibly higher dry-out heat flux for natural circulation debris systems, which may be due to the water supply from both top and bottom surfaces of the packed beds. Considering the effects of bed height and hydraulic diameter of the packing media, a newly developed model for the Wallis coefficient, C, under natural circulation CCFL is presented. The present model can predict the experimental data with an averaged absolute error of ±7.9%. (author)

  7. High power density reactors based on direct cooled particle beds

    International Nuclear Information System (INIS)

    Powell, J.R.; Horn, F.L.

    1985-01-01

    Reactors based on direct cooled HTGR type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out long the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBR's) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed. 12 figs

  8. Evaluation of co-pyrolysis petrochemical wastewater sludge with lignite in a thermogravimetric analyzer and a packed-bed reactor: Pyrolysis characteristics, kinetics, and products analysis.

    Science.gov (United States)

    Mu, Lin; Chen, Jianbiao; Yao, Pikai; Zhou, Dapeng; Zhao, Liang; Yin, Hongchao

    2016-12-01

    Co-pyrolysis characteristics of petrochemical wastewater sludge and Huolinhe lignite were investigated using thermogravimetric analyzer and packed-bed reactor coupled with Fourier transform infrared spectrometer and gas chromatography. The pyrolysis characteristics of the blends at various sludge blending ratios were compared with those of the individual materials. Thermogravimetric experiments showed that the interactions between the blends were beneficial to generate more residues. In packed-bed reactor, synergetic effects promoted the release of gas products and left less liquid and solid products than those calculated by additive manner. Fourier transform infrared spectrometer analysis showed that main functional groups in chars gradually disappeared with pyrolysis temperatures increasing, and H 2 O, CH 4 , CO, and CO 2 appeared in volatiles during pyrolysis. Gas compositions analysis indicated that, the yields of H 2 and CO clearly increased as the pyrolysis temperature and sludge blending ratio increasing, while the changes of CH 4 and CO 2 yields were relatively complex. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Transformation of 1,1,1-trichloroethane in an anaerobic packed-bed reactor at various concentrations of 1,1,1-trichloroethane, acetate and sulfate

    NARCIS (Netherlands)

    deBest, JH; Jongema, H; Weijling, A; Doddema, HJ; Janssen, DB; Harder, W

    Biotransformation of 1,1,1-trichloroethane (CH3CCl3) was observed in an anaerobic packed-bed reactor under conditions of both sulfate reduction and methanogenesis. Acetate (1 mM) served as an electron donor. CH3CCl3 was completely converted up to the highest investigated concentration of 10 mu M.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-15

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

  11. The influence of TiO2 and aeration on the kinetics of electrochemical oxidation of phenol in packed bed reactor

    International Nuclear Information System (INIS)

    Wang Lizhang; Zhao Yuemin; Fu Jianfeng

    2008-01-01

    The electrochemical oxidation of phenolic wastewater in a lab-scale reactor, packed into granular activated carbon (GAC) with Ti/SnO 2 anodes and stainless steel cathodes, was interpreted in this study. GAC saturated rapidly if it was only used as sorbent, but application of suitable electric energy for the system simultaneously could recover the adsorption ability of GAC and maintain the continuous running effectively. The titanium dioxide (TiO 2 ) as catalyst and airflow were also applied to the electrochemical reactor to examine the enhancement for phenol oxidation process. Results revealed that the electrochemical degradation of phenol could be reasonably described by first-order kinetics. In addition, it was illustrated that acid region, increased voltage, more dosage of TiO 2 and higher aeration intensity were all beneficial parameters for phenol oxidation rates. By inspecting the relationship between the rate constants (k) and influencing factors, respectively, an overall kinetic model for phenol oxidation was proposed. The kinetics obtained from the experiments under corresponding electrochemical conditions could provide an accurate estimation of phenol concentration effluent and better design of the packed bed reactor

  12. Process engineering and optimization of glycerol separation in a packed-bed reactor for enzymatic biodiesel production.

    Science.gov (United States)

    Hama, Shinji; Tamalampudi, Sriappareddy; Yoshida, Ayumi; Tamadani, Naoki; Kuratani, Nobuyuki; Noda, Hideo; Fukuda, Hideki; Kondo, Akihiko

    2011-11-01

    A process model for efficient glycerol separation during methanolysis in an enzymatic packed-bed reactor (PBR) was developed. A theoretical glycerol removal efficiency from the reaction mixture containing over 30% methyl esters was achieved at a high flow rate of 540 ml/h. To facilitate a stable operation of the PBR system, a batch reaction prior to continuous methanolysis was conducted using oils with different acid values and immobilized lipases pretreated with methyl esters. The reaction system successfully attained the methyl ester content of over 30% along with reduced viscosity and water content. Furthermore, to obtain a high methyl ester content above 96% continuously, long-term lipase stability was confirmed by operating a bench-scale PBR system for 550 h, in which the intermediates containing methyl esters and residual glycerides were fed into the enzyme-packed columns connected in series. Therefore, the developed process model is considered useful for industrial biodiesel production. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Biodegradation of p-nitrophenol using Arthrobacter chlorophenolicus A6 in a novel upflow packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Pakshirajan, Kannan; Ghosh, Pranab Kumar

    2011-06-15

    A novel packed bed reactor (PBR) was designed with cross flow aeration at multiple ports along the depth to improve the hydrodynamic conditions of the reactor, and the biodegradation efficiency of Arthrobacter chlorophenolicus A6 on p-nitrophenol (PNP) removal in PBR at different PNP loading rates were evaluated. The novel PBR was designed to improve the hydrodynamic features such as mixing time profile (t(m95)), oxygen mass transfer coefficient (k(L)a), and overall gas hold up capacity (ɛ(G)) of the reactor. PNP concentration in the influent was varied between 600 and 1400 mg l(-1) whereas the hydraulic retention time (HRT) in the reactor was varied between 18 and 7.5h. Complete removal of PNP was achieved in the reactor up to a PNP loading rate of 2787 mg l(-1)d(-1). More than 99.9% removal of PNP was achieved in the reactor for an influent concentration of 1400 mg l(-1) and at 18 h HRT. In the present study, PNP was utilized as sole source of carbon and energy by A. chlorophenolicus A6. Furthermore, the bioreactor showed good compatibility in handling shock loading of PNP. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. On the heat transfer in packed beds

    International Nuclear Information System (INIS)

    Sordon, G.

    1988-09-01

    The design of a fusion reactor blanket concept based on a bed of lithium containing ceramic pebbles or a mixture of ceramic and beryllium pebbles demands the knowledge of the effective thermal conductivity of pebble beds, including beds formed by a binary mixture of high conducting metallic pebbles and poorly conducting pebbles. In this work, binary mixtures of spheres of same diameter and different conductivities as well as beds formed by one type of spheres were investigated. The experimental apparatus consists of a stainless steel cylinder with a heating rod along the symmetry axis. Experiments with stagnant and flowing gas were performed. The pebbles were of Al 2 O 3 (diameter = 1, 2, 4 mm), of Li 4 SO 4 (diameter = 0.5 mm) of Al (diameter = 2 mm) and of steel (diameter = 2, 4 mm). Experimental values of the thermal conductivity and of the wall heat transfer coefficient are compared with the predicted ones. Modifications of already existing models were suggested. (orig.) [de

  15. Particle bed reactor nuclear rocket concept

    International Nuclear Information System (INIS)

    Ludewig, H.

    1991-01-01

    The particle bed reactor nuclear rocket concept consists of fuel particles (in this case (U,Zr)C with an outer coat of zirconium carbide). These particles are packed in an annular bed surrounded by two frits (porous tubes) forming a fuel element; the outer one being a cold frit, the inner one being a hot frit. The fuel element are cooled by hydrogen passing in through the moderator. These elements are assembled in a reactor assembly in a hexagonal pattern. The reactor can be either reflected or not, depending on the design, and either 19 or 37 elements, are used. Propellant enters in the top, passes through the moderator fuel element and out through the nozzle. Beryllium used for the moderator in this particular design to withstand the high radiation exposure implied by the long run times

  16. Investigation of hydrodynamic behavior of a pilot-scale trickle bed reactor packed with hydrophobic catalyst using radiotracer technique

    International Nuclear Information System (INIS)

    Kumar, Rajesh; Mohan, Sadhana; Pant, H.J.; Sharma, V.K.; Mahajani, S.M.

    2010-01-01

    Exchange of isotopes of hydrogen between aqueous phase and hydrogen gas is one of the most efficient methods for separation of hydrogen isotopes and is commonly used for production of heavy water or removal of tritium from tritiated water effluents. The isotope exchange reaction can be effectively executed in a counter-current trickle bed reactor (TBR) packed with a novel metal (Pt, Pd, Ni) based hydrophobic catalyst as the conventional novel metal based hydrophilic catalysts become ineffective after they come in contact with liquid effluents. The overall exchange reaction in the TBR mainly consists of a gas-liquid mass transfer process that transfers reactants from liquid to gaseous phase followed by an isotopic exchange reaction between the reactants in gaseous phase in presence of a solid hydrophobic catalyst. However, due to water repellent nature of the catalyst, poor liquid distribution in the reactor is normally observed that deteriorates the gas-liquid mass transfer. Therefore, it was thought that if a mixture of hydrophobic catalyst and a suitable hydrophilic mass transfer packing is used to fill the TBR column then, it can improve the distribution or mixing of the liquid and gas phase and thus improve the gas-liquid mass transfer and overall performance of the reactor and needs to be confirmed

  17. Biodegradation of phenolic waste liquors in stirred-tank, packed-bed, and fluidized-bed bioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Holladay, D W; Hancher, G W; Chilcote, D D; Scott, C D

    1978-11-01

    The biological degradation of phenolic scrub liquors similar to those that arise in coal conversion processes was studied for symbiotic bacterial populations contained in a continuously stirred tank bioreactor, a three-phase packed-bed bioreactor, and a three-phase, fluidized-bed bioreactor. The conversions of phenol compounds were comparable in the three-phase, packed-bed bioreactor and the continuously stirred tank bioreactor; however, the packed-bed bioreactor degradation rates were as much as twice those in the continuously stirred tank bioreactor, and packed-bed bioreactor retention times were as low as one- tenth those of the continuously stirred tank bioreactors (minimum time was 12 hours).

  18. Method for immobilizing particulate materials in a packed bed

    Science.gov (United States)

    Even, Jr., William R.; Guthrie, Stephen E.; Raber, Thomas N.; Wally, Karl; Whinnery, LeRoy L.; Zifer, Thomas

    1999-01-01

    The present invention pertains generally to immobilizing particulate matter contained in a "packed" bed reactor so as to prevent powder migration, compaction, coalescence, or the like. More specifically, this invention relates to a technique for immobilizing particulate materials using a microporous foam-like polymer such that a) the particulate retains its essential chemical nature, b) the local movement of the particulate particles is not unduly restricted, c) bulk powder migration and is prevented, d) physical and chemical access to the particulate is unchanged over time, and e) very high particulate densities are achieved. The immobilized bed of the present invention comprises a vessel for holding particulate matter, inlet and an outlet ports or fittings, a loosely packed bed of particulate material contained within the vessel, and a three dimensional porous matrix for surrounding and confining the particles thereby fixing the movement of individual particle to a limited local position. The established matrix is composed of a series of cells or chambers comprising walls surrounding void space, each wall forming the wall of an adjacent cell; each wall containing many holes penetrating through the wall yielding an overall porous structure and allowing useful levels of gas transport.

  19. Investigation of the Time Evolution and Species Production in a 2-Dimensional Packed Bed Reactor

    Science.gov (United States)

    Engeling, Kenneth; Kruszelnicki, Juliusz; Kushner, Mark; Foster, John

    2016-09-01

    Plasma production in microporous media has potential to enable a number of technologies ranging from flameless combustion to environmental hazard mitigation addressing air borne pollutants. Packed bed reactors (PBRs) is one such technology that relies on plasma production in microporous media. The physics of plasma production and transport in such media however remains poorly understood. In order to better understand the plasma propagation and plasma driven chemical reaction within microporous media, absorption spectroscopy and time-resolved imaging diagnostics are being utilized. We report on plasma driven species formation and plasma discharge spatial structure and evolution characteristics found in the 2-dimensional representation of a PBR. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  20. Packed-bed reactor/silent-discharge plasma design data report

    International Nuclear Information System (INIS)

    1996-05-01

    In 1992, Congress passed the Federal Facility Compliance Act requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). The DOE Albuquerque Operations Office (AL) currently does not have adequate systems to treat the mixed wastes generated and stored at the nine DOE-AL sites. In response to the need for mixed-waste treatment capacity, DOE-AL organized a Treatment Selection Team under the Mixed-Waste Treatment Program (MWTP) to match mixed wastes with treatment options and develop a strategy for treatment of its mixed waste. The strategy developed by the Treatment Selection Team, as described in the AL Mixed-Waste Treatment Plan (DOE 1994), is to use available off-site commercial treatment facilities for all wastes that can be successfully and cost-effectively treated by such facilities. Where no appropriate commercial treatment facilities exist, mobile treatment units (MTUs) would be developed to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste must not only address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. The packed-bed reactor/silent discharge plasma was chosen as a potential candidate for the treatment of the mixed wastes. The process is described

  1. Packed-bed reactor/silent-discharge plasma design data report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    In 1992, Congress passed the Federal Facility Compliance Act requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) land disposal restrictions (LDRs). The DOE Albuquerque Operations Office (AL) currently does not have adequate systems to treat the mixed wastes generated and stored at the nine DOE-AL sites. In response to the need for mixed-waste treatment capacity, DOE-AL organized a Treatment Selection Team under the Mixed-Waste Treatment Program (MWTP) to match mixed wastes with treatment options and develop a strategy for treatment of its mixed waste. The strategy developed by the Treatment Selection Team, as described in the AL Mixed-Waste Treatment Plan (DOE 1994), is to use available off-site commercial treatment facilities for all wastes that can be successfully and cost-effectively treated by such facilities. Where no appropriate commercial treatment facilities exist, mobile treatment units (MTUs) would be developed to treat wastes at the sites where the wastes are generated. Treatment processes used for mixed waste must not only address the hazardous component (i.e., meet LDRs) but also must contain the radioactive component in a form that allows final disposal while protecting workers, the public, and the environment. The packed-bed reactor/silent discharge plasma was chosen as a potential candidate for the treatment of the mixed wastes. The process is described.

  2. Ethanol production by immobilized yeast and its CO2 gas effects on a packed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cho, G M; Choi, C Y; Choi, Y D; Han, M H

    1982-10-01

    Immobilised yeast trapped in an alginate matrix demonstrated maximum activity at 30 degrees C and showed no pH effect between 3 and 7. Substrate inhibition was observed at glucose concentrations above 8% but the immobilised cells retained 70% of their maximum activity at 20% glucose concentration. The operation stability of immobilised cells was lower in simple glucose solution than in the activation medium in which only 20% of the activity was lost after 10 days operation. Inactivated immobilised yeast beads were reactivated by incubation in activation medium without a significant increase in cell numbers in a bead. During the operation of the immobilised yeast in a packed bed reactor, CO/sub 2/ gas accumulation adversely affected the reactor performance. An ideal plus flow reactor, not taking into account the formation of CO/sub 2/ gas bubbles and the presence of mass trasnfer resistance, was simulated using a kinetic model for the production of ethanol and the simulation results were compared with the actual reactor performance to determine the CO/sub 2/ gas effect, quantitatively. Up to 45% of the substrate conversion was lost due to the accumulation of CO/sub 2/ gas bubbles in all cases. (Refs. 21).

  3. Oxidation of SO{sub 2} in a trickle bed reactor packed with activated carbon at low liquid flow rates

    Energy Technology Data Exchange (ETDEWEB)

    Suyadal, Y.; Oguz, H. [Ankara Univ. (Turkey). Dept. of Chemical Engineering

    2000-07-01

    In this study, the oxidation of SO{sub 2} on activated carbon (AcC) by using distilled water and air was carried out in a laboratory scale trickle bed reactor (TBR). Distilled water and air containing 1.7% (v/v) SO{sub 2} were fed co-currently downward through a fixed bed of AcC particles in a range of 1-7 cm{sup 3}/s and 10-27 cm{sup 3}/s, respectively. H{sub 2}SO{sub 3}/H{sub 2}SO{sub 4} solutions were the products obtained in the liqiuid phase. Steady-state experiments were performed in a column of 0.15 m packing height and 0.047 m column diameter at 20 C and atmospheric pressure. (orig.)

  4. Numerical Simulation of Flow and Heat Transfer in Structured Packed Beds with Smooth or Dimpled Spheres at Low Channel to Particle Diameter Ratio

    Directory of Open Access Journals (Sweden)

    Shiyang Li

    2018-04-01

    Full Text Available Packed beds are widely used in catalytic reactors or nuclear reactors. Reducing the pressure drop and improving the heat transfer performance of a packed bed is a common research aim. The dimpled structure has a complex influence on the flow and heat transfer characteristics. In the present study, the flow and heat transfer characteristics in structured packed beds with smooth or dimpled spheres are numerically investigated, where two different low channel to particle diameter ratios (N = 1.00 and N = 1.15 are considered. The pressure drop and the Nusselt number are obtained. The results show that, for N = 1.00, compared with the structured packed bed with smooth spheres, the structured packed bed with dimpled spheres has a lower pressure drop and little higher Nusselt number at 1500 < ReH < 14,000, exhibiting an improved overall heat transfer performance. However, for N = 1.15, the structured packed bed with dimpled spheres shows a much higher pressure drop, which dominantly affects the overall heat transfer performance, causing it to be weaker. Comparing the different channel to particle diameter ratios, we find that different configurations can result in: (i completely different drag reduction effect; and (ii relatively less influence on heat transfer enhancement.

  5. Fuel Design for Particle-Bed Reactors for Thermal Propulsion Applications

    Science.gov (United States)

    Husser, Dewayne L.; Evans, Robert S.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    The design of particle bed reactor (PBR) fuels is an iterative process involving close coordination of design and manufacturing operations. The process starts with the generation of an initial particle design, based on a knowledge of the system requirements and interfaces (such as, fissile loading requirements, coolant type, exit gas temperatures, operation time, number of cycles, contacting materials, etc.). The designer must consider materials property data, heat-transfer and thermal-hydraulic characteristics of the particle and particle bed, and available (or anticipated) manufacturing technology. The design process also uses parametric studies to identify the influences of composition, size, and coating thickness on fuel performance. This resulting design is then used to provide a target manufacturing specification against which initial manufacturing development can be assessed and which provides the framework for manufacturing and testing derived feedback that can be incorporated into the subsequent particle design modifications. In this paper, an example of this design process for a hypothetical particle using a (U,Zr)C kernel and a NbC outer coating designed for a thermal propulsion application is given.

  6. Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

    International Nuclear Information System (INIS)

    Dai, Weijing; Pupeschi, Simone; Hanaor, Dorian; Gan, Yixiang

    2017-01-01

    Highlights: • This study explicitly demonstrates the influence of the gas pressure on the effective thermal conductivity of pebble beds. • The gas pressure influence is shown to correlated to the pebble size. • The effective thermal conductivity is linked to thermal-mechanical properties of pebbles and packing structure. - Abstract: Lithium ceramics have been considered as tritium breeder materials in many proposed designs of fusion breeding blankets. Heat generated in breeder pebble beds due to nuclear breeding reaction must be removed by means of actively cooled plates while generated tritiums is recovered by purge gas slowly flowing through beds. Therefore, the effective thermal conductivity of pebble beds that is one of the governing parameters determining heat transport phenomenon needs to be addressed with respect to mechanical status of beds and purge gas pressure. In this study, a numerical framework combining finite element simulation and a semi-empirical correlation of gas gap conduction is proposed to predict the effective thermal conductivity. The purge gas pressure is found to vary the effective thermal conductivity, in particular with the presence of various sized gaps in pebble beds. Random packing of pebble beds is taken into account by an approximated correlation considering the packing factor and coordination number of pebble beds. The model prediction is compared with experimental observation from different sources showing a quantitative agreement with the measurement.

  7. Influence of gas pressure on the effective thermal conductivity of ceramic breeder pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Weijing [School of Civil Engineering, The University of Sydney, Sydney (Australia); Pupeschi, Simone [Institute for Applied Materials, Karlsruhe Institute of Technology (KIT) (Germany); Hanaor, Dorian [School of Civil Engineering, The University of Sydney, Sydney (Australia); Institute for Materials Science and Technologies, Technical University of Berlin (Germany); Gan, Yixiang, E-mail: yixiang.gan@sydney.edu.au [School of Civil Engineering, The University of Sydney, Sydney (Australia)

    2017-05-15

    Highlights: • This study explicitly demonstrates the influence of the gas pressure on the effective thermal conductivity of pebble beds. • The gas pressure influence is shown to correlated to the pebble size. • The effective thermal conductivity is linked to thermal-mechanical properties of pebbles and packing structure. - Abstract: Lithium ceramics have been considered as tritium breeder materials in many proposed designs of fusion breeding blankets. Heat generated in breeder pebble beds due to nuclear breeding reaction must be removed by means of actively cooled plates while generated tritiums is recovered by purge gas slowly flowing through beds. Therefore, the effective thermal conductivity of pebble beds that is one of the governing parameters determining heat transport phenomenon needs to be addressed with respect to mechanical status of beds and purge gas pressure. In this study, a numerical framework combining finite element simulation and a semi-empirical correlation of gas gap conduction is proposed to predict the effective thermal conductivity. The purge gas pressure is found to vary the effective thermal conductivity, in particular with the presence of various sized gaps in pebble beds. Random packing of pebble beds is taken into account by an approximated correlation considering the packing factor and coordination number of pebble beds. The model prediction is compared with experimental observation from different sources showing a quantitative agreement with the measurement.

  8. Thermal-hydraulic study of fixed bed nuclear reactor (FBNR), in FCC, BCC and pseudo-random configurations of the core through CFD method

    International Nuclear Information System (INIS)

    Luna, M.; Chavez, I.; Cajas, D.; Santos, R.

    2015-01-01

    The study of thermal-hydraulic performance of a fixed bed nuclear reactor (FBNR) core and the effect of the porosity was studied by the CFD method with 'SolidWorks' software. The representative sections of three different packed beds arrangements were analyzed: face-centered cubic (FCC), body-centered cubic (BCC), and a pseudo-random, with values of porosity of 0.28, 0.33 and 0.53 respectively. The minimum coolant flow required to avoid the phase change for each one of the configurations was determined. The results show that the heat transfer rate increases when the porosity value decreases, and consequently the minimum coolant flow in each configuration. The results of minimum coolant flow were: 728.51 kg/s for the FCC structure, 372.72 kg/s for the BCC, and 304.96 kg/s for the pseudo-random. Meanwhile, the heat transfer coefficients in each packed bed were 6480 W/m 2 *K, 3718 W/m 2 *K and 3042 W/m 2 *K respectively. Finally the pressure drop was calculated, and the results were 0.588 MPa for FCC configuration, 0.033 MPa for BCC and 0.017 MPa for the pseudo-random one. This means that with a higher porosity, the fluid can circulate easier because there are fewer obstacles to cross, so there are fewer energy losses. (authors)

  9. High temperature energy storage performances of methane reforming with carbon dioxide in a tubular packed reactor

    International Nuclear Information System (INIS)

    Lu, Jianfeng; Chen, Yuan; Ding, Jing; Wang, Weilong

    2016-01-01

    Highlights: • Energy storage of methane reforming in a tubular packed reactor is investigated. • Thermochemical storage efficiency approaches maximum at optimal temperature. • Sensible heat and heat loss play important roles in the energy storage system. • The reaction and energy storage models of methane reforming reactor are established. • The simulated methane conversion and energy storage efficiency fit with experiments. - Abstract: High temperature heat transfer and energy storage performances of methane reforming with carbon dioxide in tubular packed reactor are investigated under different operating conditions. Experimental results show that the methane reforming in tubular packed reactor can efficiently store high temperature thermal energy, and the sensible heat and heat loss besides thermochemical energy storage play important role in the total energy storage process. When the operating temperature is increased, the thermochemical storage efficiency first increases for methane conversion rising and then decreases for heat loss rising. As the operating temperate is 800 °C, the methane conversion is 79.6%, and the thermochemical storage efficiency and total energy efficiency can be higher than 47% and 70%. According to the experimental system, the flow and reaction model of methane reforming is established using the laminar finite-rate model and Arrhenius expression, and the simulated methane conversion and energy storage efficiency fit with experimental data. Along the flow direction, the fluid temperature in the catalyst bed first decreases because of the endothermic reaction and then increases for the heat transfer from reactor wall. As a conclusion, the maximum thermochemical storage efficiency will be obtained under optimal operating temperature and optimal flow rate, and the total energy efficiency can be increased by the increase of bed conductivity and decrease of heat loss coefficient.

  10. Development of Chinese HTR-PM pebble bed equivalent conductivity test facility

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Cheng; Yang, Xingtuan; Jiang, Shengyao [Tsinghua Univ., Beijing (China). Inst. of Nuclear and New Energy Technology

    2016-01-15

    The first two 250-MWt high-temperature reactor pebble bed modules (HTR-PM) have been installing at the Shidaowan plant in Shandong Province, China. The values of the effective thermal conductivity of the pebble bed core are essential parameters for the design. For their determination, Tsinghua University in China has proposed a full-scale heat transfer experiment to conduct comprehensive thermal transfer tests in packed pebble bed and to determine the effective thermal conductivity.

  11. Modeling and Simulation of the Hydrogenation of α-Methylstyrene on Catalytically Active Metal Foams as Tubular Reactor Packing

    Directory of Open Access Journals (Sweden)

    Farzad Lali

    2016-01-01

    Full Text Available This work presents a one-dimensional reactor model for a tubular reactor packed with a catalytically active foam packing with a pore density of 30 PPI in cocurrent upward flow in the example of hydrogenation reaction of α-methylstyrene to cumene. This model includes material, enthalpy, and momentum balances as well as continuity equations. The model was solved within the parameter space applied for experimental studies under assumption of a bubbly flow. The method of orthogonal collocation on finite elements was applied. For isothermal and polytropic processes and steady state conditions, axial profiles for concentration, temperature, fluid velocities, pressure, and liquid holdup were computed and the conversions for various gas and liquid flow rates were validated with experimental results. The obtained results were also compared in terms of space time yield and catalytic activity with experimental results and stirred tank and also with random packed bed reactor. The comparison shows that the application of solid foams as reactor packing is advantageous compared to the monolithic honeycombs and random packed beds.

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

    Science.gov (United States)

    Motil, Brian J.; Balakotaiah, Vemuri

    2001-01-01

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

  13. Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-De Jesus, A.; Romano-Baez, F.J.; Leyva-Amezcua, L.; Juarez-Ramirez, C.; Ruiz-Ordaz, N. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico); Galindez-Mayer, J. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico)], E-mail: cmayer@encb.ipn.mx

    2009-01-30

    For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A{sub D}/A{sub R} ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values {epsilon}{sub G}, and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies ({approx}95%), and by the stoichiometric release of chloride ions from the halogenated compound ({approx}80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions)

  14. Long-term studies in COD elimination and nitrification in an overcongested packed-bed reactor (biofilter); Langzeituntersuchungen zur CSB-Elimination und Nitrifikation in einem ueberstauten Festbettreaktor (Biofilter)

    Energy Technology Data Exchange (ETDEWEB)

    Engelhart, M.; Dichtl, N. [Technische Univ. Braunschweig (Germany). Inst. fuer Siedlungswasserwirtschaft

    1999-07-01

    On a semi-technical scale, two process combinations were tested for their suitability for COD elimination and nitrification in combination with an overcongested packed-bed reactor (biofilter). (orig.) [German] Im halbtechnischen Massstab wurden zwei Verfahrenskombinationen unter Einbeziehung eines ueberstauten Festbettreaktors (Biofilter) auf ihre Tauglichkeit zur CSB-Elimination und Nitrifikation untersucht. (orig.)

  15. Improving thermal efficiency and increasing production rate in the double moving beds thermally coupled reactors by using differential evolution (DE) technique

    International Nuclear Information System (INIS)

    Karimi, Mohsen; Rahimpour, Mohammad Reza; Rafiei, Razieh; Shariati, Alireza; Iranshahi, Davood

    2016-01-01

    Highlights: • Double moving bed thermally coupled reactor is modeled in two dimensions. • The required heat of naphtha process is attained with nitrobenzene hydrogenation. • DE optimization method is applied to optimize operating conditions. • Hydrogen, aromatic and aniline productions increase in the proposed configuration. - Abstract: According to the global requirements for energy saving and the control of global warming, multifunctional auto-thermal reactors as a novel concept in the process integration (PI) have risen up in the recent years. In the novel modification presented in this study, the required heat of endothermic naphtha reforming process has been supplied by nitrobenzene hydrogenation reaction. In addition, the enhancement of reactor performance, such as the increase of production rate, has become a key issue in the diverse industries. Thus, Differential Evolution (DE) technique is applied to optimize the operating conditions (temperature and pressure) and designing parameters of a thermally coupled reactor with double moving beds. Ultimately, the obtained results of the proposed model are compared with non-optimized and conventional model. This model results in noticeable reduction in the operational costs as well as enhancement of the net profit of the plant. The increase in the hydrogen and aromatic production shows the superiority of the proposed model.

  16. The influence of TiO{sub 2} and aeration on the kinetics of electrochemical oxidation of phenol in packed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lizhang [College of Environment and Spatial Informatics, China University of Mining and Technology, South Jiefang Road, Quanshan District, Xuzhou City, Jiangsu 221008 (China)], E-mail: wlzh0731@126.com; Zhao Yuemin [School of Chemical Engineering and Technology, China University of Mining and Technology, South Jiefang Road, Quanshan District, Xuzhou City, Jiangsu 221008 (China)], E-mail: ymzhao@cumt.edu.cn; Fu Jianfeng [Department of Environmental Engineering, Southeast University, Nanjing City, Jiangsu 210096 (China)

    2008-12-30

    The electrochemical oxidation of phenolic wastewater in a lab-scale reactor, packed into granular activated carbon (GAC) with Ti/SnO{sub 2} anodes and stainless steel cathodes, was interpreted in this study. GAC saturated rapidly if it was only used as sorbent, but application of suitable electric energy for the system simultaneously could recover the adsorption ability of GAC and maintain the continuous running effectively. The titanium dioxide (TiO{sub 2}) as catalyst and airflow were also applied to the electrochemical reactor to examine the enhancement for phenol oxidation process. Results revealed that the electrochemical degradation of phenol could be reasonably described by first-order kinetics. In addition, it was illustrated that acid region, increased voltage, more dosage of TiO{sub 2} and higher aeration intensity were all beneficial parameters for phenol oxidation rates. By inspecting the relationship between the rate constants (k) and influencing factors, respectively, an overall kinetic model for phenol oxidation was proposed. The kinetics obtained from the experiments under corresponding electrochemical conditions could provide an accurate estimation of phenol concentration effluent and better design of the packed bed reactor.

  17. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor.

    Directory of Open Access Journals (Sweden)

    Shohreh Azizi

    Full Text Available For the effective application of a modified packed bed biofilm reactor (PBBR in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l concentrations of combined heavy metals at an optimum HRT condition (2 hours, while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l, is capable of removing the industrial contamination in wastewater.

  18. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor

    Science.gov (United States)

    Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater. PMID:27186636

  19. Liquid distribution in trickle-bed reactor; Distribution du liquide en reacteur a lit ruisselant

    Energy Technology Data Exchange (ETDEWEB)

    Marcandelli, C.; Wild, G. [Centre National de la Recherche Scientifique (CNRS-ENSIC), Lab. des Sciences du Genie Chimique, 54 - Nancy (France); Lamine, A.S. [CNRS-Universite de Paris-Nord, Lab. d' Ingenierie des Materiaux et des Hautes Pressions, 93 - Villetaneuse (France); Bernard, J.R. [Elf Antar France, Centre de Recherche Elf de Solaize, 69 - Solaize (France)

    2000-07-01

    The aim of this study is to develop techniques to qualify the efficiency of liquid distribution in trickle-bed reactors, using cold mockups. The experimental setup consists mainly in a 0.3-m-ID packed-bed column with three different plates used to vary the quality of inlet liquid distribution. Liquid distribution has been qualified using several techniques: global pressure drop measurements, global RTD (Residence-Time Distribution) of the liquid, local heat transfer probes, capacitance tomography, collector at the bottom of the reactor with nine equal zones. The bed pressure drop and the overall external liquid saturation decrease when the maldistribution increases; quantitative information is however difficult to obtain this way. Global RTD of the liquid allows quantifying of the average liquid distribution in the bed. The local thermal sensors give an indication of local liquid velocity and indicate possible local maldistribution of the liquid (scale mm) even when global distribution is good. Concerning the results obtained with the collector, a maldistribution index is defined ranging from 0 (ideal distribution) to 1 (worst possible distribution), and the influence of the different operating parameters (gas and liquid velocities, particle shape) is discussed. (authors)

  20. Direct contact condensation in packed beds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Klausner, James F.; Mei, Renwei; Knight, Jessica [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2006-12-15

    A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated air inlet temperatures of 36, 40 and 43{sup o}C. The temperature and humidity data have been collected at the inlet and exit of the packed bed for different water to air mass flow ratios that vary between 0 and 2.5. A one-dimensional model based on conservation principles has been developed, which predicts the variation of temperature, humidity, and condensation rate through the condenser stages. Agreement between the model and experiments is very good. It is observed that the countercurrent flow stage condensation effectiveness is significantly higher than that for the co-current stage. The condensation heat and mass transfer rates were found to decrease when water blockages occur within the packed bed. Using high-speed digital cinematography, it was observed that this problem can occur at any operating condition, and is dependent on the packing surface wetting characteristics. This observation is used to explain the requirement for two different empirical constants, depending on packing diameter, suggested by Onda for the air side mass transfer coefficient correlation. (author)

  1. Modeling and optimization of sunflower oil methanolysis over quicklime bits in a packed bed tubular reactor using the response surface methodology

    International Nuclear Information System (INIS)

    Miladinović, Marija R.; Stamenković, Olivera S.; Banković, Predrag T.; Milutinović-Nikolić, Aleksandra D.; Jovanović, Dušan M.; Veljković, Vlada B.

    2016-01-01

    Highlights: • Sunflower oil methanolysis in a continuous packed bed reactor was optimized. • Thermally-activated, low-cost quicklime bits were used as a catalyst. • Process was optimized by 3"3 full factorial design and Box-Behnken design. • Box-Behnken design is recommended for optimizing biodiesel production processes. • FAME content in the ester phase obtained under the optimum conditions was >98%. - Abstract: The effect of the residence time (i.e. liquid flow rate through the reactor), methanol-to-oil molar ratio and reaction temperature on the fatty acid methyl esters (FAMEs) content at the output of a continuous packed bed tubular reactor was modeled by the response surface methodology (RSM) combined with the 3"3 full factorial design (FFD) with replication or the Box-Behnken design (BBD) with five center points. The methanolysis of sunflower oil was carried out at the residence time of 1.0, 1.5 and 2.0 h, the methanol-to-oil molar ratios of 6:1, 12:1 and 18:1 and the reaction temperature of 40, 50 and 60 °C under the atmospheric pressure. Based on the used experimental designs, the model equations containing only linear and two-factor interaction terms were developed for predicting the FAME content, which were validated through the use of the unseen data. Applying the analysis of variance (ANOVA), all three factors were shown to have a significant influence on the FAME content. Acceptable statistical predictability and accuracy resulted from both designs since the values of the coefficient of determination were close to unity while the values of the mean relative percentage deviation were relatively low (<±10%). In addition, both designs predicted the maximum FAME content of above 99%, which agreed closely with the actual FAME content (98.8%). The same optimal reaction temperature (60 °C) and residence time (2.0 h) were determined by both designs while the BBD model suggested a slightly lower methanol-to-oil molar ratio (12.2:1) than the 3"3 FFD

  2. Thermo-mechanical parametric analysis of packed-bed thermocline energy storage tanks

    International Nuclear Information System (INIS)

    González, Ignacio; Pérez-Segarra, Carlos David; Lehmkuhl, Oriol; Torras, Santiago; Oliva, Assensi

    2016-01-01

    Highlights: • A numerical model of packed-bed thermocline thermal storage for CSP is presented. • Up-to-date commercial configurations are tested both thermally and structurally. • Promising thermal performance is obtained with a temperature difference of 100 °C. • Reliable factors of safety against material yielding and ratcheting can be obtained. • Cyclic relaxation-traction elastic wall stresses arise with plant normal operation. - Abstract: A packed-bed thermocline tank represents a proved cheaper thermal energy storage for concentrated solar power plants compared with the commonly-built two-tank system. However, its implementation has been stopped mainly due to the vessel’s thermal ratcheting concern, which would compromise its structural integrity. In order to have a better understanding of the commercial viability of thermocline approach, regarding energetic effectiveness and structural reliability, a new numerical simulation platform has been developed. The model dynamically solves and couples all the significant components of the subsystem, being able to evaluate its thermal and mechanical response over plant normal operation. The filler material is considered as a cohesionless bulk solid with thermal expansion. For the stresses on the tank wall the general thermoelastic theory is used. First, the numerical model is validated with the Solar One thermocline case, and then a parametric analysis is carried out by settling this storage technology in two real plants with a temperature rise of 100 °C and 275 °C. The numerical results show a better storage performance together with the lowest temperature difference, but both options achieve suitable structural factors of safety with a proper design.

  3. Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

    International Nuclear Information System (INIS)

    Seungwoo Paek; Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

    2006-01-01

    Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

  4. Effects of electrode geometry on the performance of dielectric barrier/packed-bed discharge plasmas in benzene degradation

    International Nuclear Information System (INIS)

    Jiang, Nan; Lu, Na; Shang, Kefeng; Li, Jie; Wu, Yan

    2013-01-01

    Highlights: • Benzene was successfully degraded by dielectric barrier/packed-bed discharge plasmas. • Different electrode geometry has distinct effect on plasmas oxidation performance. • Benzene degradation and energy performance were enhanced when using the coil electrode. • The reaction products were well determined by online FTIR analysis. -- Abstract: In this study, the effects of electrode geometry on benzene degradation in a dielectric barrier/packed-bed discharge plasma reactor with different electrodes were systematically investigated. Three electrodes were employed in the experiments, these were coil, bolt, and rod geometries. The reactor using the coil electrode showed better performance in reducing the dielectric loss in the barrier compared to that using the bolt or rod electrodes. In the case of the coil electrode, both the benzene degradation efficiency and energy yield were higher than those for the other electrodes, which can be attributed to the increased role of surface mediated reactions. Irrespective of the electrode geometry, the packed-bed discharge plasma was superior to the dielectric barrier discharge plasma in benzene degradation at any specific applied voltage. The main gaseous products of benzene degradation were CO, CO 2 , H 2 O, and formic acid. Discharge products such as O 3 , N 2 O, N 2 O 5 , and HNO 3 were also detected in the outlet gas. Moreover, the presence of benzene inhibited the formation of ozone because of the competing reaction of oxygen atoms with benzene. This study is expected to offer an optimized approach combining dielectric barrier discharge and packed-bed discharge to improve the degradation of gaseous pollutants

  5. Summary of particle bed reactor designs for the Space Nuclear Thermal Propulsion Program

    Science.gov (United States)

    Powell, J. R.; Ludewig, H.; Todosow, M.

    1993-09-01

    A summary report of the Particle Bed Reactor (PBR) designs considered for the space nuclear thermal propulsion program has been prepared. The first chapters outline the methods of analysis, and their validation. Monte Carlo methods are used for the physics analysis, several new algorithms are used for the fluid dynamics heat transfer and engine system analysis, and commercially available codes are used for the stress analysis. A critical experiment, prototypic of the PBR was used for the physics validation, and blowdown experiments using fuel beds of prototypic dimensions were used to validate the power extraction capabilities from particle beds. In all four different PBR rocket reactor designs were studied to varying degrees of detail. They varied in power from 400 MW to 2000 MW. These designs were all characterized by a negative prompt coefficient, due to Doppler feedback, and the feedback due to moderator heat up varied from slightly negative to slightly positive. In all practical cases, the coolant worth was positive, although core configurations with negative coolant worth could be designed. In all practical cases the thrust/weight ratio was greater than 20.

  6. Hydrogenotrophic denitrification in a packed bed reactor: effects of hydrogen-to-water flow rate ratio.

    Science.gov (United States)

    Lee, J W; Lee, K H; Park, K Y; Maeng, S K

    2010-06-01

    Hydrogen dissolution and hydrogenotrophic denitrification performance were investigated in a lab-scale packed bed reactor (PBR) by varying the hydrogen flow rate and hydraulic retention time (HRT). The denitrification performance was enhanced by increasing the hydrogen flow rate and HRT as a result of high dissolved hydrogen concentration (0.39mg/L) and utilization efficiencies (79%). In this study, the hydrogen-to-water flow rate ratio (Q(g)/Q(w)) was found to be a new operating factor representing the two parameters of hydrogen flow rate and HRT. Hydrogen dissolution and denitrification efficiency were nonlinearly and linearly correlated with the Q(g)/Q(w), respectively. Based on its excellent linear correlation with denitrification efficiency, Q(g)/Q(w) should be greater than 2.3 to meet the WHO's guideline of nitrate nitrogen for drinking water. This study demonstrates that Q(g)/Q(w) is a simple and robust factor to optimize hydrogen-sparged bioreactors for hydrogenotrophic denitrification. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Thermal safety analysis for pebble bed blanket fusion-fission hybrid reactor

    International Nuclear Information System (INIS)

    Wei Renjie

    1998-01-01

    Pebble bed blanket hybrid reactor may have more advantages than slab element blanket hybrid reactor in nuclear fuel production and nuclear safety. The thermo-hydraulic calculations of the blanket in the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor developed in China are carried out using the Code THERMIX and auxiliary code. In the calculations different fuel pebble material and steady state, depressurization and total loss of flow accident conditions are included. The results demonstrate that the conceptual design of the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor with dump tank is feasible and safe enough only if the suitable fuel pebble material is selected and the suitable control system and protection system are established. Some recommendations for due conceptual design are also presented

  8. Water infiltration and heat transfer in one dimensional unsaturated packed beds; Fuhowa ryushi sonai no ichijigen suibun nagare to dennetsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, K; Akahori, M; Hattori, M [Nagaoka University of Technology, Niigata (Japan); Shiraishi, N [Toshiba Corp., Tokyo (Japan)

    1998-05-25

    Water and heat transport in unsaturated packed beds due to supplying hot water have been investigated experimentally and theoretically. Using various sizes of glass beads, capillary pressure and permeability in packed beds were measured in unsaturated beds. The distributions in water saturation and temperature were predicted for one dimensional packed bed, based on a model assuming local thermal equilibrium among water, gas and particles at any specific space. The predicted temperature distributions were compared with the experimental results obtained using various glass sizes. In layered packed beds, water saturation becomes discontinuous at the interface of two layers because of the difference of the water characteristics between two beds. Water penetrates faster in coarse-over fine-textured profile compared with in fine-over coarse-textured profile. Similarly, the temperature rises faster in former profile under the same supplied heat quantity. 11 refs., 13 figs., 1 tab.

  9. Optimal oxygen feeding policy to maximize the production of Maleic anhydride in unsteady state fixed bed catalytic reactors

    Directory of Open Access Journals (Sweden)

    E. Ali

    2017-07-01

    Full Text Available The effect of different oxygen feeding scenarios in a fixed bed reactor for the production of Maleic anhydride (MA is studied. Two reactor configurations were examined. In the first configuration, a cross flow reactor (CFR with 4 discrete feeding points is considered. Another configuration is the conventional packed-bed reactor (PBR with a single feed. Nonlinear Model Predictive Controller (NLMPC was used as optimal controller to operate the CFR in dynamic mode and to optimize the multiple feed dosages in order to enhance the MA yield. The simulation results indicated that different combinations of the four feed ratios can operate the reactor at the best value for the yield provided the first feeding point is kept as low as possible. For the packed bed reactor configuration, a single oxygen feed is considered and is optimized transiently by NLMPC. The simulation outcomes showed that the reactor performance in terms of the produced MA mole fraction can also be enhanced to the same magnitude obtained by CFR configuration. This improvement requires decreasing the oxygen ratio in the reactor single feed by 70%.

  10. Thermal-hydraulic analysis of an annular fuel element: The Achilles' heel of the particle bed reactor

    International Nuclear Information System (INIS)

    Dibben, M.J.; Tuttle, R.F.

    1993-01-01

    The low pressure nuclear thermal propulsion (LPNTP) concept offers significant improvements in rocket engine specific impulse over rockets employment chemical propulsion. This study investigated a parametric thermal-hydraulic analysis of an annular fueld element, also referred to as a fuel pipe, using the computer code ATHENA (Advanced Thermal Hydraulic Energy Network Analyzer). The fuelpipe is an annular particle bed fuel element of the reactor with radially inward flow of hydrogen through the element. In this study, the outlet temperature of the hydrogen is parametrically related to key effects, including the reactor power at two different pressure drops, the effect of power coupling for in-core testing, and the effect of hydrogen flow rates. Results show that the temperature is linearly related to the reactor power, but not to pressure drop, and that cross flow inside the fuelpipe occurs at approximately 0.3 percent of the radial flow rates

  11. Deuterium exchange reaction in a trickle bed packed with a mixture of hydrophobic catalyst and hydrophilic packings

    Energy Technology Data Exchange (ETDEWEB)

    Seungwoo Paek [KAERI (Korea, Republic of); Heui-Joo Choi; DO-Hee Ahn; Kwang-Rag Kim; Minsoo Lee; Sung-Paal Yim; Hongsuk Chung

    2006-07-01

    Full text of publication follows: The isotopic exchange reaction between hydrogen and water on the platinum supported catalysts provides a useful step for separating hydrogen isotopes such as deuterium and tritium. The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy waste water streams because of its high separation factor and mild operating conditions. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. This paper deals with the experiments for the hydrogen isotopic exchange reaction in a trickle bed reactor packed with a hydrophobic catalyst in order to develop the catalytic column of the CECE. Hydrophobic Pt/SDBC catalyst which has been developed for the LPCE column of WTRF (Wolsong Tritium Removal Facility) was tested in a trickle bed reactor. The catalyst column was packed with a mixture of hydrophobic catalyst and hydrophilic packing (Dixon gauze ring) to improve liquid distribution and vapor/liquid transfer area. An experimental apparatus was built for the test of the catalyst at various temperatures and gas velocities. The catalyst was packed wet into the column and water was injected at the top through a liquid distributor and trickled through a catalyst mixture. Hydrogen gas passed up the column and deuterium was transferred to water stream flowing counter currently. The temperature of the column was controlled to maintain at 60 deg. C using water jackets around the reactor and equilibrator, a feed waster heater, and a circulation water heater. A metal bellows pump was used to circulate the hydrogen gas at the typical flow rate of 60 LPM.The reactor pressure was controlled to maintain at 135 kPa (abs) by a water column. Gas samples were drawn off from the top and bottom of the column. The difference in deuterium concentration between the inlet and outlet gas samples was analyzed using Gas

  12. Biotransformation of ferulic acid to vanillin in the packed bed-stirred fermentors.

    Science.gov (United States)

    Yan, Lei; Chen, Peng; Zhang, Shuang; Li, Suyue; Yan, Xiaojuan; Wang, Ningbo; Liang, Ning; Li, Hongyu

    2016-10-06

    We performed the biotransformation of ferulic acid to vanillin using Bacillus subtilis (B. subtilis) in the stirring packed-bed reactors filled with carbon fiber textiles (CFT). Scanning electron microscope (SEM), HPLC, qRT-PCR and ATP assay indicated that vanillin biotransformation is tightly related to cell growth, cellar activity and the extent of biofilm formation. The biotransformation was affected by hydraulic retention time (HRT), temperature, initial pH, stirring speed and ferulic acid concentration, and the maximum vanillin production was obtained at 20 h, 35 °C, 9.0, 200 rpm, 1.5 g/L, respectively. Repeated batch biotransformation performed under this optimized condition showed that the maximum productivity (0.047 g/L/h) and molar yield (60.43%) achieved in immobilized cell system were 1.84 and 3.61 folds higher than those achieved in free cell system. Therefore, the stirring reactor packed with CFT carrier biofilm formed by B. subtilis represented a valid biocatalytic system for the production of vanillin.

  13. Integration of coal gasification and packed bed CLC for high efficiency and near-zero emission power generation

    NARCIS (Netherlands)

    Spallina, V.; Romano, M.C.; Chiesa, P.; Gallucci, F.; Sint Annaland, van M.; Lozza, G.

    2014-01-01

    A detailed thermodynamic analysis has been carried out of large-scale coal gasification-based power plant cycles with near zero CO2 emissions, integrated with chemical looping combustion (CLC). Syngas from coal gasification is oxidized in dynamically operated packed bed reactors (PBRs), generating a

  14. Comparison of correlations for heat transfer in sphere-pac beds

    International Nuclear Information System (INIS)

    Fundamenski, W.R.; Gierszewski, P.J.

    1991-08-01

    The design of a tritium breeding blanket for a fusion reactor requires the knowledge of heat transfer within the blanket. In this paper three models for effective bed heat transfer are compared against the experimental database in order to choose a reference correlation to be used in blanket design. Two parameters are used to describe heat transfer in a packed bed: effective thermal conductivity of the bed, and a heat transfer coefficient at the bed-solid interface

  15. Comparative study between fluidized bed and fixed bed reactors in methane reforming with CO2 and O2 to produce syngas

    International Nuclear Information System (INIS)

    Jing Qiangshan; Lou Hui; Mo Liuye; Zheng Xiaoming

    2006-01-01

    Reforming of methane with carbon dioxide and oxygen was investigated over Ni/MgO-SiO 2 catalysts using fixed bed and fluidized bed reactors. The conversions of CH 4 and CO 2 in a fluidized bed reactor were close to thermodynamic equilibrium. The activity and stability of the catalyst in the fixed bed reactor were lower than that in the fluidized bed reactor due to carbon deposition and nickel sintering. TGA and TEM techniques were used to characterize the spent catalysts. The results showed that a lot of whisker carbon was found on the catalyst in the rear of the fixed bed reactor, and no deposited carbon was observed on the catalysts in the fluidized bed reactor after reaction. It is suggested that this phenomenon is related to a permanent circulation of catalyst particles between the oxygen rich and oxygen free zones. That is, fluidization of the catalysts in the fluidized bed reactor favors inhibiting deposited carbon and thermal uniformity in the reactor

  16. Immobilised native plant cysteine proteases: packed-bed reactor for white wine protein stabilisation.

    Science.gov (United States)

    Benucci, Ilaria; Lombardelli, Claudio; Liburdi, Katia; Acciaro, Giuseppe; Zappino, Matteo; Esti, Marco

    2016-02-01

    This research presents a feasibility study of using a continuous packed-bed reactor (PBR), containing immobilised native plant cysteine proteases, as a specific and mild alternative technique relative to the usual bentonite fining for white wine protein stabilisation. The operational parameters for a PBR containing immobilised bromelain (PBR-br) or immobilised papain (PBR-pa) were optimised using model wine fortified with synthetic substrate (Bz-Phe-Val-Arg-pNA). The effectiveness of PBR-br, both in terms of hazing potential and total protein decrease, was significantly higher than PBR-pa, in all the seven unfined, white wines used. Among the wines tested, Sauvignon Blanc, given its total protein content as well as its very high intrinsic instability, was selected as a control wine to evaluate the effect of the treatment on wine as to its soluble protein profile, phenolic composition, mineral component, and sensory properties. The treatment in a PBR containing immobilised bromelain appeared effective in decreasing both wine hazing potential and total protein amount, while it did not significantly affect the phenol compounds, the mineral component nor the sensory quality of wine. The enzymatic treatment in PBR was shown to be a specific and mild technique for use as an alternative to bentonite fining for white wine protein stabilisation.

  17. CLC in packed beds using syngas and CuO/Al2O3: Model description and experimental validation

    International Nuclear Information System (INIS)

    Hamers, H.P.; Gallucci, F.; Cobden, P.D.; Kimball, E.; Sint Annaland, M. van

    2014-01-01

    Highlights: • CLC with CuO/Al 2 O 3 and syngas and air has been demonstrated experimentally. • Model predicts accurately only if kinetics describe the complete solid reduction. • CuO/Al 2 O 3 is proven to catalyze the reversed water gas shift reaction. • H 2 O is more effective to suppress carbon deposition on CuO/Al 2 O 3 than CO 2 . • The OC reaction rate is not permanently affected by exposure to H 2 S. - Abstract: The objective of this work is to study the performance of the oxygen carrier in a packed bed with periodic switching between oxidizing and reducing conditions. In this paper the performance of CuO/Al 2 O 3 as the oxygen carrier in a packed bed reactor with syngas as the fuel are investigated, while also studying the (possible) carbon deposition and the effect of sulphur impurities on the stability of the carrier. Both experiments and simulations are used in this work. Cyclic experiments (oxidation with air and reduction with syngas) have been carried out in a lab scale packed bed reactor with 13 wt% CuO/Al 2 O 3 . The experimental results were well described by a 1D reactor model, provided that critical attention was given to the reaction rate for the complete reduction reaction, including a dramatic decrease in reaction rate at high solid conversions. Feeding syngas (p H2 = p CO = 0.1 bar) resulted in 1.1% carbon deposition of the feed. Steam was proven to be more effective in reducing carbon deposition than CO 2 . Moreover, it has been found that CuO/Al 2 O 3 catalyzed the water gas shift reaction and the reaction rate was not permanently affected by exposure to H 2 S, two key factors for CLC operation. The results of this work imply that CuO/Al 2 O 3 is an effective oxygen carrier as the first packed bed reactor in a TSCLC process and that the developed model is able to describe the performance at larger scales accurately

  18. Experimental Study on Pressure Drop and Flow Dispersion in Packed Bed of Natural Zeolite

    Directory of Open Access Journals (Sweden)

    Ruya Petric Marc

    2018-01-01

    Full Text Available The use of conventional correlation for pressure drop and dispersion coefficient calculation may result in inaccurate values for zeolite packed bed as the correlations are generally developed for regularly shaped and uniformly sized particles. To support the research on the application of modified natural zeolite as tar cracking catalyst, the research on the hydrodynamic behaviour of zeolite packed bed has been conducted. Experiments were carried out using a glass column with diameter of 37.8 mm. Natural zeolite with particle size of about 2.91 to 6.4 mm was applied as packing material in the column, and the bed height was varied at 9, 19 and 29 cm. Air was used as the fluid that flows through the bed and nitrogen was used as a tracer for residence time distribution determination. Air flow rates were in the range of 20 to 100 mL/s which correspond to the laminar-transitional flow regime. The pressure drops through the bed were in the range of 1.7 to 95.6 Pa, depending on the air flow rate and bed height. From these values, the parameters in the Ergun equation were estimated, taking into account the contribution by wall effect when the ratio of column to particle diameter is low. The viscous and inertial term constants in the Ergun equation calculated ranges from 179 to 199 and 1.41 to 1.47 respectively while the particle sphericity ranges from 0.56 to 0.59. The reactor Peclet number were determined to range from 5.2 to 5.5, which indicated significant deviation from a plug flow condition.

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

    International Nuclear Information System (INIS)

    Gerasev, Alexander P.

    2017-01-01

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

  20. Factors affecting biological reduction of CO{sub 2} into CH{sub 4} using a hydrogenotrophic methanogen in a fixed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Hyung; Pak, Daewon [Seoul National University of Science and Technology, Seoul (Korea, Republic of); Chang, Won Seok [Korea District Heating Corp, Seongnam (Korea, Republic of)

    2015-10-15

    Biological conversion of CO{sub 2} was examined in a fixed bed reactor inoculated with anaerobic mixed culture to investigate influencing factors, the type of packing material and the composition of the feeding gas mixture. During the operation of the fixed bed reactor by feeding the gas mixture (80% H{sub 2} and 20% CO{sub 2} based on volume basis), the volumetric CO{sub 2} conversion rate was higher in the fixed bed reactor packed with sponge due to its large surface area and high mass transfer from gas to liquid phase compared with PS ball. Carbon dioxide loaded into the fixed bed reactor was not completely converted because some of H{sub 2} was used for biomass growth. When a mole ratio of H{sub 2} to CO{sub 2} in the feeding gas mixture increased from 4 to 5, CO{sub 2} was completely converted into CH{sub 4}. The packing material with large surface area is effective in treating gaseous substrate such as CO{sub 2} and H{sub 2}. H{sub 2}, electron donor, should be providing more than required according to stoichiometry because some of it is used for biomass growth.

  1. Effects of random pebble distribution on the multiplication factor in HTR pebble bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Auwerda, G.J., E-mail: g.j.auwerda@tudelft.n [Department of Physics of Nuclear Reactors at the Delft University of Technology, Mekelweg 15, Delft (Netherlands); Kloosterman, J.L.; Lathouwers, D.; Hagen, T.H.J.J. van der [Department of Physics of Nuclear Reactors at the Delft University of Technology, Mekelweg 15, Delft (Netherlands)

    2010-08-15

    In pebble bed reactors the pebbles have a random distribution within the core. The usual approach in modeling the bed is homogenizing the entire bed. To quantify the errors arising in such a model, this article investigates the effect on k{sub eff} of three phenomena in random pebble distributions: non-uniform packing density, neutron streaming in between the pebbles, and variations in Dancoff factor. For a 100 cm high cylinder with reflective top and bottom boundary conditions 25 pebble beds were generated. Of each bed three core models were made: a homogeneous model, a zones model including density fluctuations, and an exact model with all pebbles modeled individually. The same was done for a model of the PROTEUS facility. k{sub eff} calculations were performed with three codes: Monte Carlo, diffusion, and finite element transport. By comparing k{sub eff} of the homogenized and zones model the effect of including density fluctuations in the pebble bed was found to increase k{sub eff} by 71 pcm for the infinite cylinder and 649 pcm for PROTEUS. The large value for PROTEUS is due to the low packing fraction near the top of the pebble bed, causing a significant lower packing fraction for the bulk of the pebble bed in the homogenized model. The effect of neutron streaming was calculated by comparing the zones model with the exact model, and was found to decrease k{sub eff} by 606 pcm for the infinite cylinder, and by 1240 pcm for PROTEUS. This was compared with the effect of using a streaming correction factor on the diffusion coefficient in the zones model, which resulted in {Delta}{sub streaming} values of 340 and 1085 pcm. From this we conclude neutron streaming is an important effect in pebble bed reactors, and is not accurately described by the correction factor on the diffusion coefficient. Changing the Dancoff factor in the outer part of the pebble bed to compensate for the lower probability of neutrons to enter other fuel pebbles caused no significant changes

  2. High throughput photo-oxidations in a packed bed reactor system.

    Science.gov (United States)

    Kong, Caleb J; Fisher, Daniel; Desai, Bimbisar K; Yang, Yuan; Ahmad, Saeed; Belecki, Katherine; Gupton, B Frank

    2017-12-01

    The efficiency gains produced by continuous-flow systems in conducting photochemical transformations have been extensively demonstrated. Recently, these systems have been used in developing safe and efficient methods for photo-oxidations using singlet oxygen generated by photosensitizers. Much of the previous work has focused on the use of homogeneous photocatalysts. The development of a unique, packed-bed photoreactor system using immobilized rose bengal expands these capabilities as this robust photocatalyst allows access to and elaboration from these highly useful building blocks without the need for further purification. With this platform we were able to demonstrate a wide scope of singlet oxygen ene, [4+2] cycloadditions and heteroatom oxidations. Furthermore, we applied this method as a strategic element in the synthesis of the high-volume antimalarial artemisinin. Copyright © 2017. Published by Elsevier Ltd.

  3. Supported Photocatalyst for Removal of Emerging Contaminants from Wastewater in a Continuous Packed-Bed Photoreactor Configuration

    Directory of Open Access Journals (Sweden)

    Mª Emma Borges

    2015-02-01

    Full Text Available Water pollution from emerging contaminants (ECs or emerging pollutants is an important environmental problem. Heterogeneous photocatalytic treatment, as advanced oxidation treatment of wastewater effluents, has been proposed to solve this problem. In this paper, a heterogeneous photocatalytic process was studied for emergent contaminants removal using paracetamol as a model contaminant molecule. TiO2 photocatalytic activity was evaluated using two photocatalytic reactor configurations: Photocatalyst solid suspension in wastewater in a stirred photoreactor and TiO2 supported on glass spheres (TGS configuring a packed bed photoreactor. The surface morphology and texture of the TGS were monitored by scanning electron microscope (SEM. The influence of photocatalyst amount and wastewater pH were evaluated in the stirred photoreactor and the influence of wastewater flowrate was tested in the packed bed photoreactor, in order to obtain the optimal operation conditions. Moreover, results obtained were compared with those obtained from photolysis and adsorption studies, using the optimal operation conditions. Good photocatalytic activities have been observed and leads to the conclusion that the heterogeneous photocatalytic system in a packed bed is an effective method for removal of emerging pollutants.

  4. Performance Study of Chromium (VI) Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

    Science.gov (United States)

    Chakraborty, Bhaswati; Indra, Suvendu; Hazra, Ditipriya; Betai, Rupal; Ray, Lalitagauri; Basu, Srabanti

    2013-01-01

    Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7. PMID:24073400

  5. Performance Study of Chromium (VI Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

    Directory of Open Access Journals (Sweden)

    Bhaswati Chakraborty

    2013-01-01

    Full Text Available Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7.

  6. Tritium sorption behavior on the percolation of tritiated water into a soil packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Furuichi, Kazuya, E-mail: kfuruichi@aees.kyushu-u.ac.jp [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Katayama, Kazunari; Date, Hiroyuki [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Takeishi, Toshiharu [Factory of Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395 (Japan); Fukada, Satoshi [Department of Advanced Energy Engineering, Kyushu University, 6-1, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2016-11-01

    Highlights: • We establish the permeation model of tritiated water in the soil layer. • Saturated hydraulic conductivity of water in soil was gained by using the model. • The isotope exchange reaction coefficient was good agreement with experimental data. - Abstract: Development of tritium transport model in natural soil is an important issue from a viewpoint of safety of fusion reactors. The spill of a large amount of tritiated water to the environment is a concern accident because huge tritiated water is handled in a fusion plant. In this work, a simple tritium transport model was proposed based on the tritium transport model in porous materials. The overall mass transfer coefficient representing isotope exchange reaction between tritiated water and structural water in soil particles was obtained by numerically analyzing the result of the percolation experiment of tritiated water into the soil packed bed. Saturated hydraulic conductivity in the natural soil packed bed was obtained to be 0.033 mm/s. By using this value, the overall mass transfer capacity coefficients representing the isotope exchange reaction between tritiated water percolating through the packed bed and overall structural water on soil particles was determined to be 6.0 × 10{sup −4} 1/s. This value is much smaller than the mass transfer capacity coefficient between tritiated water vapor and water on concrete material and metals.

  7. Pellet bed reactor for nuclear propelled vehicles: Part 1: Reactor technology

    Science.gov (United States)

    El-Genk, Mohamed S.

    1991-01-01

    The pellet bed reactor (PBR) for nuclear propelled vehicles is briefly discussed. Much of the information is given in viewgraph form. Viewgraphs include information on the layout for a Mars mission using a PBR nuclear thermal rocket, the rocket reactor layout, the fuel pellet design, materials compatibility, fuel microspheres, microsphere coating, melting points in quasibinary systems, stress analysis of microspheres, safety features, and advantages of the PBR concept.

  8. Pellet bed reactor for nuclear propelled vehicles: Part 1: Reactor technology

    International Nuclear Information System (INIS)

    El-genk, M.S.

    1991-01-01

    The pellet bed reactor (PBR) for nuclear propelled vehicles is briefly discussed. Much of the information is given in viewgraph form. Viewgraphs include information on the layout for a Mars mission using a PBR nuclear thermal rocket, the rocket reactor layout, the fuel pellet design, materials compatibility, fuel microspheres, microsphere coating, melting points in quasibinary systems, stress analysis of microspheres, safety features, and advantages of the PBR concept

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

    International Nuclear Information System (INIS)

    Han, Lu; Bollas, George M.

    2016-01-01

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

  10. Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  11. The performance of a trickle-bed reactor packed with a Pt/SDBC catalyst mixture for the CECE process

    International Nuclear Information System (INIS)

    Paek, Seungwoo; Ahn, Do-Hee; Choi, Heui-Joo; Kim, Kwang-Rag; Lee, Minsoo; Yim, Sung-Paal; Chung, Hongsuk; Song, Kyu-Min; Sohn, Soon Hwan

    2007-01-01

    The combined electrolysis and catalytic exchange (CECE) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy wastewater streams because of its high separation factor and mild operating conditions. A hydrophobic platinum/styrene-divinyl benzene copolymer (Pt/SDBC) catalyst which was developed for the liquid-phase catalytic exchange (LPCE) column of the Wolsong tritium removal facility (WTRF) has been tested in a trickle bed reactor for the design of the CECE process. An experimental apparatus has been built for the testing of the catalyst at various temperatures and gas velocities. The catalyst column was packed with a mixture of a hydrophobic catalyst and a hydrophilic packing (Dixon gauze ring) to improve the liquid distribution and vapor/liquid transfer area. Many tests have been carried out at Korea Atomic Energy Research Institute (KAERI) to measure the activity of the catalyst, K y a (1 s -1 ), under various operating conditions. K y a increases with the hydrogen flow rates in the range of 0.4-1.6 m s -1 at STP. The height of the catalyst column was determined from these K y a values according to the reaction temperatures and hydrogen flow rates

  12. The performance of a trickle-bed reactor packed with a Pt/SDBC catalyst mixture for the CECE process

    Energy Technology Data Exchange (ETDEWEB)

    Paek, Seungwoo [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)], E-mail: swpaek@kaeri.re.kr; Ahn, Do-Hee; Choi, Heui-Joo; Kim, Kwang-Rag; Lee, Minsoo; Yim, Sung-Paal; Chung, Hongsuk [Korea Atomic Energy Research Institute, 150 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Song, Kyu-Min; Sohn, Soon Hwan [Korea Electric Power Research Institute, 103-16 Munji-dong, Yuseong-gu, Daejeon 305-380 (Korea, Republic of)

    2007-10-15

    The combined electrolysis and catalytic exchange (CECE) process with a hydrophobic catalyst is a very effective method to remove small quantities of tritium from light or heavy wastewater streams because of its high separation factor and mild operating conditions. A hydrophobic platinum/styrene-divinyl benzene copolymer (Pt/SDBC) catalyst which was developed for the liquid-phase catalytic exchange (LPCE) column of the Wolsong tritium removal facility (WTRF) has been tested in a trickle bed reactor for the design of the CECE process. An experimental apparatus has been built for the testing of the catalyst at various temperatures and gas velocities. The catalyst column was packed with a mixture of a hydrophobic catalyst and a hydrophilic packing (Dixon gauze ring) to improve the liquid distribution and vapor/liquid transfer area. Many tests have been carried out at Korea Atomic Energy Research Institute (KAERI) to measure the activity of the catalyst, K{sub y}a (1 s{sup -1}), under various operating conditions. K{sub y}a increases with the hydrogen flow rates in the range of 0.4-1.6 m s{sup -1} at STP. The height of the catalyst column was determined from these K{sub y}a values according to the reaction temperatures and hydrogen flow rates.

  13. Udder health in a Danish compost bedded pack barn

    DEFF Research Database (Denmark)

    Svennesen, Line; Enevoldsen, Carsten; Bjerg, Bjarne Schmidt

    Besides welfare advantages of the compost bedded pack system (CBP) there could be a negative effect of the organic bedding on udder health. Our objectives were to evaluate the effects of a CBP on udder health compared to a free stall system (FS) with sand bedded cubicles. Within the same Danish...

  14. Battery Pack Thermal Design

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, Ahmad

    2016-06-14

    This presentation describes the thermal design of battery packs at the National Renewable Energy Laboratory. A battery thermal management system essential for xEVs for both normal operation during daily driving (achieving life and performance) and off-normal operation during abuse conditions (achieving safety). The battery thermal management system needs to be optimized with the right tools for the lowest cost. Experimental tools such as NREL's isothermal battery calorimeter, thermal imaging, and heat transfer setups are needed. Thermal models and computer-aided engineering tools are useful for robust designs. During abuse conditions, designs should prevent cell-to-cell propagation in a module/pack (i.e., keep the fire small and manageable). NREL's battery ISC device can be used for evaluating the robustness of a module/pack to cell-to-cell propagation.

  15. Analysis of an integrated packed bed thermal energy storage system for heat recovery in compressed air energy storage technology

    International Nuclear Information System (INIS)

    Ortega-Fernández, Iñigo; Zavattoni, Simone A.; Rodríguez-Aseguinolaza, Javier; D'Aguanno, Bruno; Barbato, Maurizio C.

    2017-01-01

    Highlights: •A packed bed TES system is proposed for heat recovery in CAES technology. •A CFD-based approach has been developed to evaluate the behaviour of the TES unit. •TES system enhancement and improvement alternatives are also demonstrated. •TES performance evaluated according to the first and second law of thermodynamics. -- Abstract: Compressed air energy storage (CAES) represents a very attracting option to grid electric energy storage. Although this technology is mature and well established, its overall electricity-to-electricity cycle efficiency is lower with respect to other alternatives such as pumped hydroelectric energy storage. A meager heat management strategy in the CAES technology is among the main reasons of this gap of efficiency. In current CAES plants, during the compression stage, a large amount of thermal energy is produced and wasted. On the other hand, during the electricity generation stage, an extensive heat supply is required, currently provided by burning natural gas. In this work, the coupling of both CAES stages through a thermal energy storage (TES) unit is introduced as an effective solution to achieve a noticeable increase of the overall CAES cycle efficiency. In this frame, the thermal energy produced in the compression stage is stored in a TES unit for its subsequent deployment during the expansion stage, realizing an Adiabatic-CAES plant. The present study addresses the conceptual design of a TES system based on a packed bed of gravel to be integrated in an Adiabatic-CAES plant. With this objective, a complete thermo-fluid dynamics model has been developed, including the implications derived from the TES operating under variable-pressure conditions. The formulation and treatment of the high pressure conditions were found being particularly relevant issues. Finally, the model provided a detailed performance and efficiency analysis of the TES system under charge/discharge cyclic conditions including a realistic operative

  16. Percolation behavior of tritiated water into a soil packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Honda, T.; Katayama, K.; Uehara, K.; Fukada, S. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka (Japan); Takeishi, T. [Faculty of Engineering, Kyushu University, Motooka Nishi-ku, Fukuoka (Japan)

    2015-03-15

    A large amount of cooling water is used in a D-T fusion reactor. The cooling water will contain tritium with high concentration because tritium can permeate metal walls at high temperature easily. A development of tritium handling technology for confining tritiated water in the fusion facility is an important issue. In addition, it is also important to understand tritium behavior in environment assuming severe accidents. In this study, percolation experiments of tritiated water in soil packed bed were carried out and tritium behavior in soil was discussed. Six soil samples were collected in Hakozaki campus of Kyushu University. These particle densities were of the same degree as that of general soils and moisture contents were related to BET surface area. For two soil samples used in the percolation experiment of tritiated water, saturated hydraulic conductivity agreed well with the estimating value by Creager. Tritium retention ratio in the soil packed bed was larger than water retention. This is considered to be due to an effect of tritium sorption on the surface of soil particles. The isotope exchange capacity estimated by assuming that H/T ratio of supplied tritiated water and H/T ratio of surface water of soil particle was equal was comparable to that on cement paste and mortar which were obtained by exposure of tritiated water vapor. (authors)

  17. Percolation behavior of tritiated water into a soil packed bed

    International Nuclear Information System (INIS)

    Honda, T.; Katayama, K.; Uehara, K.; Fukada, S.; Takeishi, T.

    2015-01-01

    A large amount of cooling water is used in a D-T fusion reactor. The cooling water will contain tritium with high concentration because tritium can permeate metal walls at high temperature easily. A development of tritium handling technology for confining tritiated water in the fusion facility is an important issue. In addition, it is also important to understand tritium behavior in environment assuming severe accidents. In this study, percolation experiments of tritiated water in soil packed bed were carried out and tritium behavior in soil was discussed. Six soil samples were collected in Hakozaki campus of Kyushu University. These particle densities were of the same degree as that of general soils and moisture contents were related to BET surface area. For two soil samples used in the percolation experiment of tritiated water, saturated hydraulic conductivity agreed well with the estimating value by Creager. Tritium retention ratio in the soil packed bed was larger than water retention. This is considered to be due to an effect of tritium sorption on the surface of soil particles. The isotope exchange capacity estimated by assuming that H/T ratio of supplied tritiated water and H/T ratio of surface water of soil particle was equal was comparable to that on cement paste and mortar which were obtained by exposure of tritiated water vapor. (authors)

  18. New sampling method in continuous energy Monte Carlo calculation for pebble bed reactors

    International Nuclear Information System (INIS)

    Murata, Isao; Takahashi, Akito; Mori, Takamasa; Nakagawa, Masayuki.

    1997-01-01

    A pebble bed reactor generally has double heterogeneity consisting of two kinds of spherical fuel element. In the core, there exist many fuel balls piled up randomly in a high packing fraction. And each fuel ball contains a lot of small fuel particles which are also distributed randomly. In this study, to realize precise neutron transport calculation of such reactors with the continuous energy Monte Carlo method, a new sampling method has been developed. The new method has been implemented in the general purpose Monte Carlo code MCNP to develop a modified version MCNP-BALL. This method was validated by calculating inventory of spherical fuel elements arranged successively by sampling during transport calculation and also by performing criticality calculations in ordered packing models. From the results, it was confirmed that the inventory of spherical fuel elements could be reproduced using MCNP-BALL within a sufficient accuracy of 0.2%. And the comparison of criticality calculations in ordered packing models between MCNP-BALL and the reference method shows excellent agreement in neutron spectrum as well as multiplication factor. MCNP-BALL enables us to analyze pebble bed type cores such as PROTEUS precisely with the continuous energy Monte Carlo method. (author)

  19. Dynamic model of organic pollutant degradation in three dimensional packed bed electrode reactor.

    Science.gov (United States)

    Pang, Tianting; Wang, Yan; Yang, Hui; Wang, Tianlei; Cai, Wangfeng

    2018-04-21

    A dynamic model of semi-batch three-dimensional electrode reactor was established based on the limiting current density, Faraday's law, mass balance and a series of assumptions. Semi-batch experiments of phenol degradation were carried out in a three-dimensional electrode reactor packed with activated carbon under different conditions to verify the model. The factors such as the current density, the electrolyte concentration, the initial pH value, the flow rate of organic and the initial organic concentration were examined to know about the pollutant degradation in the three-dimensional electrode reactor. The various concentrations and logarithm of concentration of phenol with time were compared with the dynamic model. It was shown that the calculated data were in good agreement with experimental data in most cases. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Nguyen, Luong N; Hai, Faisal I; Dosseto, Anthony; Richardson, Christopher; Price, William E; Nghiem, Long D

    2016-06-01

    Laccase was immobilized on granular activated carbon (GAC) and the resulting GAC-bound laccase was used to degrade four micropollutants in a packed-bed column. Compared to the free enzyme, the immobilized laccase showed high residual activities over a broad range of pH and temperature. The GAC-bound laccase efficiently removed four micropollutants, namely, sulfamethoxazole, carbamazepine, diclofenac and bisphenol A, commonly detected in raw wastewater and wastewater-impacted water sources. Mass balance analysis showed that these micropollutants were enzymatically degraded following adsorption onto GAC. Higher degradation efficiency of micropollutants by the immobilized compared to free laccase was possibly due to better electron transfer between laccase and substrate molecules once they have adsorbed onto the GAC surface. Results here highlight the complementary effects of adsorption and enzymatic degradation on micropollutant removal by GAC-bound laccase. Indeed laccase-immobilized GAC outperformed regular GAC during continuous operation of packed-bed columns over two months (a throughput of 12,000 bed volumes). Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. 3D DEM simulation and analysis of void fraction distribution in a pebble bed high temperature reactor

    International Nuclear Information System (INIS)

    Yang, Xingtuan; Gui, Nan; Tu, Jiyuan; Jiang, Shengyao

    2014-01-01

    Highlights: • We show a detailed analysis of void fraction (VF) in HTR-10 of China using DEM. • Radial distribution (RD) of VF is uniform in the core and oscillated near the wall. • Axial distribution (AD) is linearly varied along height due to effect of gravity. • Steady RD of VF in the conical base is Gaussian-like, larger than packing bed. • Joint linear and normal distribution of VF is analyzed and explained. - Abstract: The current work analyzes the radial and axial distributions of void fraction of a pebble bed high temperature reactor. A three-dimensional pebble bed corresponding to our test facility of pebble bed type gas-cooled high temperature reactor (HTR-10) in Tsinghua University is simulated via discrete element method, and the radial and axial void fraction profiles are calculated. It validates the oscillating characteristics of radial void fraction near the wall. Detailed calculations show the differences of void fraction profiles between the stationary packing bed and the dynamically discharging bed. Based on the vertically and circumferentially averaged radial distribution and horizontally averaged axial distribution of void fraction, a fully three-dimensional analytical distribution of void fraction throughout the bed is established. The results show the combined effects of gravity and void variation in the pebble bed caused by the pebble discharging. It indicates the linearly increased packing effect caused by gravity in the vertical (axial) direction and the normal distribution of void in the horizontal (radial) direction by pebble drainage. These two effects coexist in the conical base of the bed whereas only the former effect exists in the cylindrical volume of the bed

  2. State of the art of the fluidized bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Sefidvash, F.; Vilhena, M.T.M.B. de; Streck, E.; Borges, V.; Johansson, M.

    1987-01-01

    A small and simple nuclear reactors with inherent safety using the fluidized bed concept is under research and study. In this paper a brief study neutronics and thermal hydraulics of this reactor concept is presented. (Author) [pt

  3. Accumulation of BSA in Packed-bed Microfluidics

    Science.gov (United States)

    Summers, Samantha; Hu, Chuntian; Hartman, Ryan

    2012-11-01

    Alzheimers and Parkinsons are two diseases that are associated with protein deposition in the brain, causing loss of either cognitive or muscle functioning. Protein deposition diseases are considered progressive diseases since the continual aggregation of protein causes the patient's symptoms to slowly worsen over time. There are currently no known means of treatment for protein deposition diseases. Our goal is to understand the potential for packed-bed microfluidics to study protein accumulation. Measurement of the resistance to flow through micro-scale packed-beds is critical to understanding the process of protein accumulation. Aggregation in bulk is fundamentally different from accumulation on surfaces. Our study attempts to distinguish between either mechanism. The results from our experiments involving protein injection through a microfluidic system will be presented and discussed. Funding received by NSF REU Grant 1062611.

  4. A comparative study on the effective thermal conductivity of a single size beryllium pebble bed

    International Nuclear Information System (INIS)

    Abou-Sena, A.; Ying, A.; Abdou, M.

    2004-01-01

    Solid breeder blankets generally use beryllium-helium pebble beds to ensure sufficient tritium breeding. The data of the effective thermal conductivity, k eff , of beryllium pebble beds is important to the design of fusion blankets. It serves as a database for benchmarking the models of pebble beds. The objective of this paper is to review and compare the available data (obtained by several studies) of the effective thermal conductivity of beryllium pebble beds in order to address the current status of these data. Two comparisons are presented: one for the data of k eff versus bed mean temperature and the second one for the data of k eff versus external applied pressures. The data (k eff versus bed temperature) reported by Enoeda et al., Dalle Donne et al., and UCLA, have a similar particle size and packing fraction. Despite their similarity, the standard deviation values of their data are around 32%. Also, the data of the effective thermal conductivity as a function of mechanical pressure have standard deviation values of ∼50%. From the presented comparisons, significant discrepancies among the available data of k eff of the beryllium pebble beds were observed. These discrepancies may be attributed to the apparent differences among available studies, such as experiment technique, packing fraction, particle characteristics, bed dimensions, and temperature range and gradient across the bed. (author)

  5. Pore Scale Thermal Hydraulics Investigations of Molten Salt Cooled Pebble Bed High Temperature Reactor with BCC and FCC Configurations

    Directory of Open Access Journals (Sweden)

    Shixiong Song

    2014-01-01

    CFD results and empirical correlations’ predictions of pressure drop and local Nusselt numbers. Local pebble surface temperature distributions in several default conditions are investigated. Thermal removal capacities of molten salt are confirmed in the case of nominal condition; the pebble surface temperature under the condition of local power distortion shows the tolerance of pebble in extreme neutron dose exposure. The numerical experiments of local pebble insufficient cooling indicate that in the molten salt cooled pebble bed reactor, the pebble surface temperature is not very sensitive to loss of partial coolant. The methods and results of this paper would be useful for optimum designs and safety analysis of molten salt cooled pebble bed reactors.

  6. Aerobic biodegradation of 2,4-DNT and 2,6-DNT: Performance characteristics and biofilm composition changes in continuous packed-bed bioreactors

    International Nuclear Information System (INIS)

    Paca, J.; Halecky, M.; Barta, J.; Bajpai, R.

    2009-01-01

    This manuscript deals with continuous experiments for biodegradation of individual dinitrotoluenes by a defined mixed culture in packed-bed reactors (PBRs) containing either poraver or fire-clay as packing material. Removal efficiencies and volumetric biodegradation rates were measured as a function of the loading rate of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) under steady-state conditions. The poraver reactor showed higher removal efficiencies for both the DNTs. The removal efficiency for 2,4-DNT remained greater than 90% in the poraver reactor whereas it dropped steadily from 85 to 65% in the fire-clay reactor as the organic loading rates were increased from 19 to 60 mg L -1 day -1 . Similar trends were seen for the volumetric degradation rate as well. In both the reactors, 2,4-DNT degraded more effectively than 2,6-DNT. The microbial consortium was characterized both in the inoculum as well as in the operating PBR. Cell numbers per gram dry packing material were similar in the two reactors. However, there was a distinct difference in the nature of microorganisms that were found in the two packings. The fire-clay contained a larger number of cells that were not primary degraders of DNTs

  7. Aerobic biodegradation of 2,4-DNT and 2,6-DNT: performance characteristics and biofilm composition changes in continuous packed-bed bioreactors.

    Science.gov (United States)

    Paca, J; Halecky, M; Barta, J; Bajpai, R

    2009-04-30

    This manuscript deals with continuous experiments for biodegradation of individual dinitrotoluenes by a defined mixed culture in packed-bed reactors (PBRs) containing either poraver or fire-clay as packing material. Removal efficiencies and volumetric biodegradation rates were measured as a function of the loading rate of 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) under steady-state conditions. The poraver reactor showed higher removal efficiencies for both the DNTs. The removal efficiency for 2,4-DNT remained greater than 90% in the poraver reactor whereas it dropped steadily from 85 to 65% in the fire-clay reactor as the organic loading rates were increased from 19 to 60 mg L(-1)day(-1). Similar trends were seen for the volumetric degradation rate as well. In both the reactors, 2,4-DNT degraded more effectively than 2,6-DNT. The microbial consortium was characterized both in the inoculum as well as in the operating PBR. Cell numbers per gram dry packing material were similar in the two reactors. However, there was a distinct difference in the nature of microorganisms that were found in the two packings. The fire-clay contained a larger number of cells that were not primary degraders of DNTs.

  8. Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

    Directory of Open Access Journals (Sweden)

    Marian C. Bryan

    2011-08-01

    Full Text Available The performance of the ThalesNano H-Cube®, a commercial packed bed flow hydrogenator, was evaluated in the context of small scale reaction screening and optimization. A model reaction, the reduction of styrene to ethylbenzene through a 10% Pd/C catalyst bed, was used to examine performance at various pressure settings, over sequential runs, and with commercial catalyst cartridges. In addition, the consistency of the hydrogen flow was indirectly measured by in-line UV spectroscopy. Finally, system contamination due to catalyst leaching, and the resolution of this issue, is described. The impact of these factors on the run-to-run reproducibility of the H-Cube® reactor for screening and reaction optimization is discussed.

  9. Modeling stationary and dynamic pebbles in a pebble bed reactor

    International Nuclear Information System (INIS)

    Zhao, Xiang; Montgomery, Trent; Zhang, Sijun

    2011-01-01

    This paper presents a numerical study of the stationary and dynamic pebbles in a pebble bed reactor (PBR) by means of discrete element method (DEM). At first, the packing structure of stationary pebbles is simulated by filling process until the settling of pebbles into PBR. The packing structural properties are obtained and analyzed. Subsequently, when the outlet of PBR is open during the operational maintenance of PBR, the stationary pebbles start to flow downward and are removed at the bottom of PBR. The dynamic behavior of pebbles is predicted and discussed. Our results indicate the DEM can offer both macroscopic and microscopic information for PBR design calculations and safety assessment. (author)

  10. Influence of the type of organisms on the biomass hold-up in a fluidized-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Timmermans, P.; Haute, A. van

    1984-01-01

    In the last few years, the use of fluidized-bed reactors for biological wastewater treatment has got increasing attention. In 1981, Shieh et al. proposed a model to predict the biomass concentration in a fluidized-bed reactor. From this model one can see that the biofilm density plays a very important role in determining the total biomass hold-up. In this article the influence of the type of carbon source on the biomass concentration, and as a consequence the type of organisms selected, is studied. The growth of a filamentous, budforming bacteria in a reactor treating nitrate rich surface water supplied with methanol as carbon source, results in a biomass concentration only half of the concentration which can normally be obtained in a fluidized-bed reactor treating synthetic wastewater; in this latter case rod-shaped bacteria are enriched which permit a dense packing.

  11. Experimental and numerical validation of a two-region-designed pebble bed reactor with dynamic core

    International Nuclear Information System (INIS)

    Jiang, S.Y.; Yang, X.T.; Tang, Z.W.; Wang, W.J.; Tu, J.Y.; Liu, Z.Y.; Li, J.

    2012-01-01

    Highlights: ► The experimental installation has been built to investigate the pebble flow. ► The feasibility of two-region pebble bed reactor has been verified. ► The pebble flow is more uniform in a taller vessel than that in a lower vessel. ► Larger base cone angle will decrease the scale of the stagnant zone. - Abstract: The pebble flow is the principal issue for the design of the pebble bed reactor. In order to verify the feasibility of a two-region-designed pebble bed reactor, the experimental installation with a taller vessel has been built, which is proportional to the real pebble bed reactor. With the aid of the experimental installation, the stable establishment and maintenance of the two-region arrangement has been verified, at the same time, the applicability of the DEM program has been also validated. Research results show: (1) The pebble's bouncing on the free surface is an important factor for the mixing of the different colored pebbles. (2) Through the guide plates installed in the top of the pebble packing, the size of the mixing zone can be reduced from 6–7 times to 3–4 times the pebble diameter. (3) The relationship between the width of the central region and the ratio of loading pebbles is approximately linear in the taller vessel. (4) The heighten part of the pebble packing can improve the uniformity of the flowing in the lower. (5) To increase the base cone angle can decrease the scale of the stagnant zone. All of these conclusions are meaningful to the design of the real pebble reactor.

  12. Nuclear thermal propulsion engine based on particle bed reactor using light water steam as a propellant

    Science.gov (United States)

    Powell, James R.; Ludewig, Hans; Maise, George

    1993-01-01

    In this paper the possibility of configuring a water cooled Nuclear Thermal Propulsion (NTP) rocket, based on a Particle Bed Reactor (PBR) is investigated. This rocket will be used to operate on water obtained from near earth objects. The conclusions reached in this paper indicate that it is possible to configure a PBR based NTP rocket to operate on water and meet the mission requirements envisioned for it. No insurmountable technology issues have been identified.

  13. Nuclear thermal propulsion engine based on particle bed reactor using light water steam as a propellant

    International Nuclear Information System (INIS)

    Powell, J.R.; Ludewig, H.; Maise, G.

    1993-01-01

    In this paper the possibility of configuring a water cooled Nuclear Thermal Propulsion (NTP) rocket, based on a Particle Bed Reactor (PBR) is investigated. This rocket will be used to operate on water obtained from near earth objects. The conclusions reached in this paper indicate that it is possible to configure a PBR based NTP rocket to operate on water and meet the mission requirements envisioned for it. No insurmountable technology issues have been identified

  14. Small propulsion reactor design based on particle bed reactor concept

    International Nuclear Information System (INIS)

    Ludewig, H.; Lazareth, O.; Mughabghab, S.; Perkins, K.; Powell, J.R.

    1989-01-01

    In this paper Particle Bed Reactor (PBR) designs are discussed which use 233 U and /sup 242m/Am as fissile materials. A constant total power of 100MW is assumed for all reactors in this study. Three broad aspects of these reactors is discussed. First, possible reactor designs are developed, second physics calculations are outlined and discussed and third mass estimates of the various candidates reactors are made. It is concluded that reactors with a specific mass of 1 kg/MW can be envisioned of 233 U is used and approximately a quarter of this value can be achieved if /sup 242m/Am is used. If this power level is increased by increasing the power density lower specific mass values are achievable. The limit will be determined by uncertainties in the thermal-hydraulic analysis. 5 refs., 5 figs., 6 tabs

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

    NARCIS (Netherlands)

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

    2018-01-01

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

  16. Study on heat and mass transfer between a greenhouse considered as a solar air heater and a rock packed bed as ambient control system

    International Nuclear Information System (INIS)

    Ajona Maeztu, J.I.

    1990-01-01

    A general study on heat transfer in dry packed beds is made, with special emphasis in comparing different transient models and in identifying the required conditions by which the attained results are equivalent. The differences in thermal behaviour on packed beds, when simultaneous heat mass transfer occurs as wet air is used as heat transfer fluid and exchanges heat and water with the solid in the bed, is analyzed. We modelize wet packed beds considering them as one dimension adsorbents beds, with dispersive and non-dispersive models, where adsorption, condensation-evaporation and liquid water downward flow from condensate phenomena are present. Models were solved numerically and experiments with a rock bed with dry and wet air through it, were made to test assumptions and to further understand the behavior of the system, obtaining a pretty good agreement between expected and measured profiles of the temperature evolution within the packed bed. As a possible application of the wet rock bed for storage purposes, a forced ventilation greenhouse was characterized as a wet air solar heater and analyzed the energetic potential of storing the heat that has to be rejected during daytime to control the crop ambient conditions, in a rock bed for later use at night for heating. (author)

  17. CFD study on the supercritical carbon dioxide cooled pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-15

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

  18. Performance of a desiccant assisted packed bed passive solar dryer for copra processing

    Directory of Open Access Journals (Sweden)

    Padmanaban Govindarajulu

    2017-01-01

    Full Text Available In this paper, the performance of a novel desiccant assisted packed bed passive solar dryer was evaluated for copra processing and compared with conventional passive solar dryer. This novel solar dryer consists of a desiccant assisted packed bed solar air heater attached with a dryer cabin. The desiccant and phase change materials packed in the solar air heater has control the humidity and retains the heat for longer duration, respectively. The performance of the dryer was evaluated (in terms of drying time to attain the final equilibrium moisture content, drying rate, specific moisture extraction rate, pick-up efficiency, and dryer efficiency under the meteorological conditions of Coimbatore city in India during March and April 2016. The copra was dried from initial moisture content (wet basis of about 52% to the final moisture content (wet basis of about 8% in 62 hours with specific moisture extraction rate of 0.82 kg/kWh. The drying time was reduced by about 44 hours when compared to the conventional passive solar dryer. The dryer pick-up efficiency was varied between about 10% and 65%. The average dryer thermal efficiency was calculated to be about 32%. The quality of final dried product was found to be good.

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

    International Nuclear Information System (INIS)

    Prasser, Horst-Michael

    2014-01-01

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

  20. Transient core-debris bed heat-removal experiments and analysis

    International Nuclear Information System (INIS)

    Ginsberg, T.; Klein, J.; Klages, J.; Schwarz, C.E.; Chen, J.C.

    1982-08-01

    An experimental investigation is reported of the thermal interaction between superheated core debris and water during postulated light-water reactor degraded core accidents. Data are presented for the heat transfer characteristics of packed beds of 3 mm spheres which are cooled by overlying pools of water. Results of transient bed temperature and steam flow rate measurements are presented for bed heights in the range 218 mm-433 mm and initial particle bed temperatures between 530K and 972K. Results display a two-part sequential quench process. Initial frontal cooling leaves pockets or channels of unquenched spheres. Data suggest that heat transfer process is limited by a mechanism of countercurrent two-phase flow. An analytical model which combines a bed energy equation with either a quasisteady version of the Lipinski debris bed model or a critical heat flux model reasonably well predicts the characteristic features of the bed quench process. Implications with respect to reactor safety are discussed

  1. Simulation of turbulent flow in a packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Guo, B.; Yu, A. [Centre for Simulation and Modelling of Particulate Systems and School of Material Science and Engineering, The University of New South Wales, Sydney 2052 (Australia); Wright, B.; Zulli, P. [BlueScope Steel Research Laboratories, P.O. Box 202, Port Kembla, NSW 2505 (Australia)

    2006-05-15

    Numerous models for simulating the flow and transport in packed beds have been proposed in the literature with few reported applications. In this paper, several turbulence models for porous media are applied to the gas flow through a randomly packed bed and are examined by means of a parametric study against some published experimental data. These models predict widely different turbulent eddy viscosity. The analysis also indicates that deficiencies exist in the formulation of some model equations and selection of a suitable turbulence model is important. With this realization, residence time distribution and velocity distribution are then simulated by considering a radial profile of porosity and turbulence induced dispersion, and the results are in good agreement with the available experimental data. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  2. Local description of the energy transfer process in a packed bed heat exchanger

    International Nuclear Information System (INIS)

    Costa, M.L.M.; Sampaio, R.; Gama, R.M.S. da.

    1990-01-01

    The energy transfer process in a packed-bed heat exchanger, in counter0flow arrangement is considered. The phenomenon is described through a Continuum Theory of Mixtures approach, in which fluid and solid (porous matrix) are regarded as continuous constituents possessing, each one, its own temperature and velocity fields. The heat 'exchangers consists of two channels, separated by an impermeable wall without thermal resistence, in which there exists a saturated flow. Some particular cases are simulated. (author)

  3. Discussion on Design Transients of Pebble-bed High Temperature Gas-cooled Reactor

    International Nuclear Information System (INIS)

    Wang Yan; Li Fu; Zheng Yanhua

    2014-01-01

    In order to assure high quality for the components and their supports in the reactor coolant system, etc., some thermal-hydraulic transient conditions will be selected and researched for equipment design evaluation to satisfy the requirements ASME code, which are based on the conservative estimates of the magnitude and frequency of the temperature and pressure transients resulting from various operating conditions in the plant. In the mature design on pressurized water reactor, five conditions are considered. For the developing advanced pebble-bed high temperature gas-cooled reactor(HTGR), its design and operation has much difference with other reactors, so the transients of the pebble-bed high temperature gas-cooled reactor have distinctive characteristics. In this paper, the possible design transients of the pebble-bed HTGR will be discussed, and the frequency of design transients for equipment fatigue analysis and stress analysis due to cyclic stresses is also studied. The results will provide support for the design and construct of the pebble-bed HTGR. (author)

  4. Thermal-hydraulics of actinide burner reactors

    International Nuclear Information System (INIS)

    Takizuka, Takakazu; Mukaiyama, Takehiko; Takano, Hideki; Ogawa, Toru; Osakabe, Masahiro.

    1989-07-01

    As a part of conceptual study of actinide burner reactors, core thermal-hydraulic analyses were conducted for two types of reactor concepts, namely (1) sodium-cooled actinide alloy fuel reactor, and (2) helium-cooled particle-bed reactor, to examine the feasibility of high power-density cores for efficient transmutation of actinides within the maximum allowable temperature limits of fuel and cladding. In addition, calculations were made on cooling of actinide fuel assembly. (author)

  5. Modeling stationary and moving pebbles in a pebble bed reactor

    International Nuclear Information System (INIS)

    Zhao, Xiang; Montgomery, Trent; Zhang, Sijun

    2015-01-01

    Highlights: • The stationary and moving pebbles in a PBR are numerically studied by DEM. • The packing structure of stationary pebbles is simulated by a filling process. • The packing structural properties are obtained and analyzed. • The dynamic behavior of pebbles is predicted and discussed. - Abstract: This paper presents a numerical study of the stationary and moving pebbles in a pebble bed reactor (PBR) by means of discrete element method (DEM). The packing structure of stationary pebbles is simulated by a filling process that terminates with the settling of the pebbles into a PBR. The packing structural properties are obtained and analyzed. Subsequently, when the outlet of the PBR is opened during the operation of the PBR, the stationary pebbles start to flow downward and are removed at the bottom of the PBR. The dynamic behavior of pebbles is predicted and discussed. Our results indicate the DEM can offer both macroscopic and microscopic information for PBR design calculations and safety assessment

  6. A unique nuclear thermal rocket engine using a particle bed reactor

    Science.gov (United States)

    Culver, Donald W.; Dahl, Wayne B.; McIlwain, Melvin C.

    1992-01-01

    Aerojet Propulsion Division (APD) studied 75-klb thrust Nuclear Thermal Rocket Engines (NTRE) with particle bed reactors (PBR) for application to NASA's manned Mars mission and prepared a conceptual design description of a unique engine that best satisfied mission-defined propulsion requirements and customer criteria. This paper describes the selection of a sprint-type Mars transfer mission and its impact on propulsion system design and operation. It shows how our NTRE concept was developed from this information. The resulting, unusual engine design is short, lightweight, and capable of high specific impulse operation, all factors that decrease Earth to orbit launch costs. Many unusual features of the NTRE are discussed, including nozzle area ratio variation and nozzle closure for closed loop after cooling. Mission performance calculations reveal that other well known engine options do not support this mission.

  7. 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)

  8. Upflow anaerobic sludge blanket-hollow centered packed bed (UASB-HCPB) reactor for thermophilic palm oil mill effluent (POME) treatment

    International Nuclear Information System (INIS)

    Poh, P.E.; Chong, M.F.

    2014-01-01

    Upflow anaerobic sludge blanket-hollow centered packed bed (UASB-HCPB) reactor was developed with the aim to minimize operational problems in the anaerobic treatment of Palm Oil Mill Effluent (POME) under thermophilic conditions. The performance of UASB-HCPB reactor on POME treatment was investigated at 55 °C. Subsequent to start-up, the performance of the UASB-HCPB reactor was evaluated in terms of i) effect of hydraulic retention time (HRT); ii) effect of organic loading rate (OLR); and iii) effect of mixed liquor volatile suspended solid (MLVSS) concentration on thermophilic POME treatment. Start-up up of the UASB-HCPB reactor was completed in 36 days, removing 88% COD and 90% BOD respectively at an OLR of 28.12 g L −1  d −1 , producing biogas with 52% of methane. Results from the performance study of the UASB-HCPB reactor on thermophilic POME treatment indicated that HRT of 2 days, OLR of 27.65 g L −1  d −1 and MLVSS concentration of 14.7 g L −1 was required to remove 90% of COD and BOD, 80% of suspended solid and at the same time produce 60% of methane. - Highlights: • UASB-HCPB was proposed for POME treatment under thermophilic conditions. • Start-up up of the UASB-HCPB reactor was completed in 36 days. • 88% COD and 90% BOD were removed at an OLR of 28.12 g COD/L.day during start-up. • HRT of 2 days and OLR of 27.65 g COD/L.day was required to produce 60% methane. • Methanosarcina sp. forms the majority of microbial population in the UASB section

  9. Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst.

    Science.gov (United States)

    Son, Sung Mo; Kimura, Hiroko; Kusakabe, Katsuki

    2011-01-01

    Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

    Science.gov (United States)

    Ramos, A.; Filtvedt, W. O.; Lindholm, D.; Ramachandran, P. A.; Rodríguez, A.; del Cañizo, C.

    2015-12-01

    Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS). We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles to product quality. A model sensitivity analysis is also performed, and the effects of some key parameters such as reactor wall emissivity and gas distributor temperature, on temperature distribution and product quality are examined. The information presented in this paper is useful for further understanding of the strengths and weaknesses of both deposition technologies, and will help in optimal temperature profiling of these systems aiming at lowering production costs without compromising the solar cell quality.

  11. Packed-Bed Reactor Study of NETL Sample 196c for the Removal of Carbon Dioxide from Simulated Flue Gas Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, James S.; Hammache, Sonia; Gray, McMahan L.; Fauth Daniel J.; Pennline, Henry W.

    2012-04-24

    An amine-based solid sorbent process to remove CO2 from flue gas has been investigated. The sorbent consists of polyethylenimine (PEI) immobilized onto silica (SiO2) support. Experiments were conducted in a packed-bed reactor and exit gas composition was monitored using mass spectrometry. The effects of feed gas composition (CO2 and H2O), temperature, and simulated steam regeneration were examined for both the silica support as well as the PEI-based sorbent. The artifact of the empty reactor was also quantified. Sorbent CO2 capacity loading was compared to thermogravimetric (TGA) results to further characterize adsorption isotherms and better define CO2 working capacity. Sorbent stability was monitored by periodically repeating baseline conditions throughout the parametric testing and replacing with fresh sorbent as needed. The concept of the Basic Immobilized Amine Sorbent (BIAS) Process using this sorbent within a system where sorbent continuously flows between the absorber and regenerator was introduced. The basic tenet is to manipulate or control the level of moisture on the sorbent as it travels around the sorbent circulation path between absorption and regeneration stages to minimize its effect on regeneration heat duty.

  12. The ESKOM pebble bed modular reactor

    International Nuclear Information System (INIS)

    Gittus, J.H.

    1999-01-01

    An audit has been made of the design, construction, safety, economics and marketability of the ESKOM pebble bed modular reactor (PBMR). In this paper that audit is briefly summarized. The principal conclusions of the audit are as follows. The design is sound. It is a logical development of the designs proposed for other, modern, high-temperature gas-cooled reactors. More than 80% of the cost of constructing and commissioning a series of PBMRs would be spent in South Africa. The PBMR is much safer than existing nuclear power reactors and for many practical purposes it may be treated as a conventional chemical plant. The PBMR is economically competitive with thermal power stations. There is a substantial global market for the PBMR. (author)

  13. Transient Effects in Fischer-Tropsch Reactor with a Fixed Bed of Catalyst Particles

    Directory of Open Access Journals (Sweden)

    I. V. Derevich

    2015-01-01

    Full Text Available Based on analysis of small temperature disturbances in the Fischer-Tropsch reactor with a fixed bed of catalyst particles various scenarios of thermal instability were investigated. There are two possible scenarios of thermal instability of the reactor. First, thermal explosion may occur due to growth of temperature disturbances inside a catalytic granule. Second scenario connected with loss of thermal stability as a result of an initial increase in temperature in the reactor volume. The boundaries of thermal stability of the reactor were estimated by solving the eigenvalue problems for spherical catalyst particles and cylindrical reactor. Processes of diffusional resistance inside the catalytic granule and heat transfer from wall of the reactor tube are taken into account. Estimation of thermal stability area is compared with the results of numerical simulation of behavior of temperature and concentration of synthesis gas.

  14. Continuous Process for Biodiesel Production in Packed Bed Reactor from Waste Frying Oil Using Potassium Hydroxide Supported on Jatropha curcas Fruit Shell as Solid Catalyst

    Directory of Open Access Journals (Sweden)

    Achanai Buasri

    2012-08-01

    Full Text Available The transesterification of waste frying oil (WFO with methanol in the presence of potassium hydroxide catalyst supported on Jatropha curcas fruit shell activated carbon (KOH/JS was studied. The catalyst systems were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM and the Brunauer–Emmett–Teller (BET method. The effects of reaction variables such as residence time, reaction temperature, methanol/oil molar ratio and catalyst bed height in packed bed reactor (PBR on the yield of biodiesel were investigated. SEM images showed that KOH was well distributed on the catalyst support. The optimum conditions for achieving the conversion yield of 86.7% consisted of a residence time of 2 h, reaction temperature of 60 °C, methanol/oil molar ratio of 16 and catalyst bed height of 250 mm. KOH/JS could be used repeatedly five times without any activation treatment, and no significant activity loss was observed. The results confirmed that KOH/JS catalyst had a great potential to be used for industrial application in the transesterification of WFO. The fuel properties of biodiesel were also determined.

  15. Pellet bed reactor for multi-modal space power

    International Nuclear Information System (INIS)

    Buden, D.; Williams, K.; Mast, P.; Mims, J.

    1987-01-01

    A review of forthcoming space power needs for both civil and military missions indicates that power requirements will be in the tens of megawatts. The electrical power requirements are envisioned to be twofold: long-duration lower power levels will be needed for station keeping, communications, and/or surveillance; short-duration higher power levels will be required for pulsed power devices. These power characteristics led to the proposal of a multi-modal space power reactor using a pellet bed design. Characteristics desired for such a multimegawatt reactor power source are standby, alert, and pulsed power modes; high-thermal output heat source (approximately 1000 MWt peak power); long lifetime station keeping power (10 to 30 years); high temperature output (1500 K to 1800 K); rapid-burst power transition; high reliability (above 95 percent); and stringent safety standards compliance. The proposed pellet bed reactor is designed to satisfy these characteristics

  16. Radioisotope tracer study in a pilot-scale trickle bed reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-07-01

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

  17. Analysis of the start-up and control of a particle bed reactor

    International Nuclear Information System (INIS)

    Lazareth, O.W.; Araj, K.J.; Horn, F.L.; Ludewig, H.; Powell, J.R.

    1987-01-01

    This study describes the modeling of start-up transients in Particle Bed Reactors (PBR) for burst electric power. Two computer programs have been developed to analyze the start-up process. The first program (named KINETIC) analyzes the entire fuel element, calculating time dependent solutions for power and the temperature distribution in the packed bed. The second program (named SPHEAT, for Spherical Heating) calculates time-dependent temperatures inside individual, cladded fuel particles. The two programs provide powerful analytical tools for evaluation of material and geometrical options, power and time constraints, and conditions that could lead to element failures

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

    Science.gov (United States)

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

    2017-05-01

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

  19. Udder health in a Danish compost bedded pack barn

    OpenAIRE

    Svennesen, Line; Enevoldsen, Carsten; Bjerg, Bjarne Schmidt; Klaas, Ilka Christine

    2014-01-01

    Besides welfare advantages of the compost bedded pack system (CBP) there could be a negative effect of the organic bedding on udder health. Our objectives were to evaluate the effects of a CBP on udder health compared to a free stall system (FS) with sand bedded cubicles. Within the same Danish organic farm, 330 multiparous cows were randomly allocated to CBP or FS. During the experimental period (EP), December 2012 to May 2013, proportions of cows with blinded teats were registered monthly a...

  20. KUGEL: a thermal, hydraulic, fuel performance, and gaseous fission product release code for pebble bed reactor core analysis

    International Nuclear Information System (INIS)

    Shamasundar, B.I.; Fehrenbach, M.E.

    1981-05-01

    The KUGEL computer code is designed to perform thermal/hydraulic analysis and coated-fuel particle performance calculations for axisymmetric pebble bed reactor (PBR) cores. This computer code was developed as part of a Department of Energy (DOE)-funded study designed to verify the published core performance data on PBRs. The KUGEL code is designed to interface directly with the 2DB code, a two-dimensional neutron diffusion code, to obtain distributions of thermal power, fission rate, fuel burnup, and fast neutron fluence, which are needed for thermal/hydraulic and fuel performance calculations. The code is variably dimensioned so that problem size can be easily varied. An interpolation routine allows variable mesh size to be used between the 2DB output and the two-dimensional thermal/hydraulic calculations

  1. Effect of oxygen on ethanol fermentation in packed-bed tapered-column reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hamamci, H.; Ryu, D.D.Y.

    1988-07-01

    In ethanol production with immobilized yeast a major problem is the provision of nutrients to these highly concentrated cells. O/sub 2/ being one of the nutrients of utmost importance to yeast cells, was fed into a column packed with beads with a cell loading of more than 40 g/l. Since addition of large volume of air or O/sub 2/ to a cylindrical column reactor would aggravate the problems of pressure build up and channelling caused by the evolving CO/sub 2/ gas, a tapered-column reactor and pulsed flow of oxygen gas was used. The supplement of O/sub 2/ gas to the tapered column increased the productivity from 21.1 g ethanol x (l gel x h)/sup -1/ to 26.7 g x (l gelxh)/sup -1/, when the ethanol concentration at the outlet was about 80 g/l. The yield coefficient of ethanol was also increased from 0.41 g ethanol/g glucose to 0.43 after O/sub 2/ supplement was started. The effects of frequency and duration of O/sub 2/ supplement were also determined.

  2. Particle Bed Reactor scaling relationships

    International Nuclear Information System (INIS)

    Slovik, G.; Araj, K.; Horn, F.L.; Ludewig, H.; Benenati, R.

    1987-01-01

    Scaling relationships for Particle Bed Reactors (PBRs) are discussed. The particular applications are short duration systems, i.e., for propulsion or burst power. Particle Bed Reactors can use a wide selection of different moderators and reflectors and be designed for such a wide range of power and bed power densities. Additional design considerations include the effect of varying the number of fuel elements, outlet Mach number in hot gas channel, etc. All of these variables and options result in a wide range of reactor weights and performance. Extremely light weight reactors (approximately 1 kg/MW) are possible with the appropriate choice of moderator/reflector and power density. Such systems are very attractive for propulsion systems where parasitic weight has to be minimized

  3. Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

    Directory of Open Access Journals (Sweden)

    Longbao Zhu

    Full Text Available An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA. The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99% in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

  4. Efficient preparation of enantiopure D-phenylalanine through asymmetric resolution using immobilized phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1 in a recirculating packed-bed reactor.

    Science.gov (United States)

    Zhu, Longbao; Zhou, Li; Huang, Nan; Cui, Wenjing; Liu, Zhongmei; Xiao, Ke; Zhou, Zhemin

    2014-01-01

    An efficient enzymatic process was developed to produce optically pure D-phenylalanine through asymmetric resolution of the racemic DL-phenylalanine using immobilized phenylalanine ammonia-lyase (RgPAL) from Rhodotorula glutinis JN-1. RgPAL was immobilized on a modified mesoporous silica support (MCM-41-NH-GA). The resulting MCM-41-NH-GA-RgPAL showed high activity and stability. The resolution efficiency using MCM-41-NH-GA-RgPAL in a recirculating packed-bed reactor (RPBR) was higher than that in a stirred-tank reactor. Under optimal operational conditions, the volumetric conversion rate of L-phenylalanine and the productivity of D-phenylalanine reached 96.7 mM h⁻¹ and 0.32 g L⁻¹ h⁻¹, respectively. The optical purity (eeD) of D-phenylalanine exceeded 99%. The RPBR ran continuously for 16 batches, the conversion ratio did not decrease. The reactor was scaled up 25-fold, and the productivity of D-phenylalanine (eeD>99%) in the scaled-up reactor reached 7.2 g L⁻¹ h⁻¹. These results suggest that the resolution process is an alternative method to produce highly pure D-phenylalanine.

  5. Development of an ultrahigh-temperature process for the enzymatic hydrolysis of lactose. IV. Immobilization of two thermostable beta-glycosidases and optimization of a packed-bed reactor for lactose conversion.

    Science.gov (United States)

    Petzelbauer, Inge; Kuhn, Bernhard; Splechtna, Barbara; Kulbe, Klaus D; Nidetzky, Bernd

    2002-03-20

    Recombinant hyperthermostable beta-glycosidases from the archaea Sulfolobus solfataricus (Ss beta Gly) and Pyrococcus furiosus (CelB) were covalently attached onto the insoluble carriers chitosan, controlled pore glass (CPG), and Eupergit C. For each enzyme/carrier pair, the protein-binding capacity, the immobilization yield, the pH profiles for activity and stability, the activity/temperature profile, and the kinetic constants for lactose hydrolysis at 70 degrees C were determined. Eupergit C was best among the carriers in regard to retention of native-like activity and stability of Ss beta Gly and CelB over the pH range 3.0-7.5. Its protein binding capacity of approximately 0.003 (on a mass basis) was one-third times that of CPG, while immobilization yields were typically 80% in each case. Activation energies for lactose conversion by the immobilized enzymes at pH 5.5 were in the range 50-60 kJ/mol. This is compared to values of approximately 75 kJ/mol for the free enzymes. Immobilization expands the useful pH range for CelB and Ss beta Gly by approximately 1.5 pH units toward pH 3.5 and pH 4.5, respectively. A packed-bed enzyme reactor was developed for the continuous conversion of lactose in different media, including whey and milk, and operated over extended reaction times of up to 14 days. The productivities of the Eupergit C-immobilized enzyme reactor were determined at dilution rates between 1 and 12 h(-1), and using 45 and 170 g/L initial lactose. Results of kinetic modeling for the same reactor, assuming plug flow and steady state, suggest the presence of mass-transfer limitation of the reaction rate under the conditions used. Formation of galacto-oligosaccharides in the continuous packed-bed reactor and in the batch reactor using free enzyme was closely similar in regard to yield and individual saccharide components produced. Copyright 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 619-631, 2002; DOI 10.1002/bit.10110

  6. Proceedings of the ANS/ASME/NRC international topical meeting on nuclear reactor thermal-hydraulics: LMFBR and HTGR advanced reactor concepts and analysis methods

    International Nuclear Information System (INIS)

    1980-01-01

    Separate abstracts are included for each of the papers presented concerning the thermal-hydraulics of LMFBR type reactors; mathematical methods in nuclear reactor thermal-hydraulics; heat transfer in gas-cooled reactors; and thermal-hydraulics of pebble-bed reactors. Two papers have been previously abstracted and input to the data base

  7. Performance of a new solar air heater with packed-bed latent storage energy for nocturnal use

    International Nuclear Information System (INIS)

    Bouadila, Salwa; Kooli, Sami; Lazaar, Mariem; Skouri, Safa; Farhat, Abdelhamid

    2013-01-01

    Highlights: • A new solar air heater collector using a phase change material. • Experimental study of the new solar air heater collector with latent storage. • Energy and exergy analysis of the solar heater with latent storage collector. • Nocturnal use of solar air heater collector. - Abstract: An experimental study was conducted to evaluate the thermal performance of a new solar air heater collector using a packed bed of spherical capsules with a latent heat storage system. Using both first and second law of thermodynamics, the energetic and exegetic daily efficiencies were calculated in Closed/Opened and Opened cycle mode. The solar energy was stored in the packed bed through the diurnal period and extracted at night. The experimentally obtained results are used to analyze the performance of the system, based on temperature distribution in different localization of the collectors. The daily energy efficiency varied between 32% and 45%. While the daily exergy efficiency varied between 13% and 25%

  8. Experimental investigations on friction laws and dryout heat flux of particulate beds packed with multi-size spheres and irregular particles

    International Nuclear Information System (INIS)

    Li, Liangxing; Ma, Weimin

    2011-01-01

    This paper is concerned with reducing uncertainty in quantification of debris bed coolability in a hypothetical severe accident of light water reactors (LWRs). A test facility named POMECO-FL is constructed to investigate the friction laws of adiabatic single and two-phase flow in a particulate bed packed with multi-size spheres or irregular particles. The same types of particles were then loaded in the test section of the POMECO-HT facility to obtain the dryout heat flux of the volumetrically heated particulate bed. The POMECO-HT facility features a high power capacity (up to 2.1 MW/m 2 ) which enables coolability study on particulate bed with broad variations in porosity and particle diameters under both top-flooding and bottom-injection conditions. The results show that given the effective particle diameter obtained from single-phase flow through the packed bed with multi-size spheres or irregular particles, both the pressure drop and the dryout heat flux of two-phase flow through the bed can be predicted by the Reed model. The bottom injection of coolant increases the dryout heat flux significantly. Meanwhile, the elevation of the dryout position is moving upwards with increasing bottom-injection flowrate. The experimental data provides insights for interpretation of debris bed coolability, as well as high-quality data for validation of the coolability analysis models and codes. (author)

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

    International Nuclear Information System (INIS)

    Pavlidis, Dimitrios; Lathouwers, Danny

    2013-01-01

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

  10. Media arrangement impacts cell growth in anaerobic fixed-bed reactors treating sugarcane vinasse: Structured vs. randomic biomass immobilization.

    Science.gov (United States)

    de Aquino, Samuel; Fuess, Lucas Tadeu; Pires, Eduardo Cleto

    2017-07-01

    This study reports on the application of an innovative structured-bed reactor (FVR) as an alternative to conventional packed-bed reactors (PBRs) to treat high-strength solid-rich wastewaters. Using the FVR prevents solids from accumulating within the fixed-bed, while maintaining the advantages of the biomass immobilization. The long-term operation (330days) of a FVR and a PBR applied to sugarcane vinasse under increasing organic loads (2.4-18.0kgCODm -3 day -1 ) was assessed, focusing on the impacts of the different media arrangements over the production and retention of biomass. Much higher organic matter degradation rates, as well as long-term operational stability and high conversion efficiencies (>80%) confirmed that the FVR performed better than the PBR. Despite the equivalent operating conditions, the biomass growth yield was different in both reactors, i.e., 0.095gVSSg -1 COD (FVR) and 0.066gVSSg -1 COD (PBR), indicating a clear control of the media arrangement over the biomass production in fixed-bed reactors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Thermomechanical interactions of particle bed-structural wall in a layered configuration. Pt. 1. Effect of particle bed thermal expansions

    International Nuclear Information System (INIS)

    Tehranian, F.

    1995-01-01

    Materials in the form of particle beds have been considered for shielding and tritium breeding as well as neutron multiplication in many of the conceptual reactor design studies. As the level of effort of the fusion blanket community in the area of out-of-pile and in-pile (ITER) testing of integrated test modules increases, so does the need for modelling capability for predicting the thermomechanical responses of the test modules under reactor environment.In this study, the thermomechanical responses of a particle bed-structural wall system in a layered configuration, subjected to bed temperature rise and/or external coolant pressure, were considered. Equations were derived which represent the dependence of the particle-to-particle and particle-to-wall contact forces and areas on the structural wall deformations and in turn on the thermomechanical loads. Using the derived equations, parametric analyses were performed to study the variations in the thermomechanical response quantities of a beryllium particle bed-stainless steel structural wall when subjected to thermomechanical loads. The results are presented in two parts. In Part I, presented in this paper, the derivation of the analytical equations and the effects of bed temperature rise are discussed. In Part II of this study, also presented in this symposium, the effects of external coolant pressure as well as the combined effects of bed temperature rise and coolant pressure on the thermomechanical responses are given.It is shown that, depending on the stiffness of the structural walls, uniform bed temperature rises in the range 100-400 C result in non-uniform effective thermal properties through the prticle bed and could increase the bed effective thermal conductivity by a factor of 2-5 and the bed-wall interface thermal conductance by even a larger factor. (orig.)

  12. Pt-catalyzed ozonation of aqueous phenol solution using high-gravity rotating packed bed

    International Nuclear Information System (INIS)

    Chang, Chia-Chi; Chiu, Chun-Yu; Chang, Ching-Yuan; Chang, Chiung-Fen; Chen, Yi-Hung; Ji, Dar-Ren; Tseng, Jyi-Yeong; Yu, Yue-Hwa

    2009-01-01

    In this study, a high-gravity rotating packed bed (HGRPB or HG) was used as a catalytic ozonation (Cat-OZ) reactor to decompose phenol. The operation of HGRPB system was carried out in a semi-batch apparatus which combines two major parts, namely the rotating packed bed (RPB) and photo-reactor (PR). The high rotating speed of RPB can give a high volumetric gas-liquid mass transfer coefficient with one or two orders of magnitude higher than those in the conventional packed beds. The platinum-containing catalyst (Dash 220N, Pt/γ-Al 2 O 3 ) and activated alumina (γ-Al 2 O 3 ) were packed in the RPB respectively to adsorb molecular ozone and the target pollutant of phenol on the surface to catalyze the oxidation of phenol. An ultra violet (UV) lamp (applicable wavelength λ = 200-280 nm) was installed in the PR to enhance the self-decomposition of molecular ozone in water to form high reactive radical species. Different combinations of advanced oxidation processes (AOPs) with the HGRPB for the degradation of phenol were tested. These included high-gravity OZ (HG-OZ), HG catalytic OZ (HG-Cat-OZ), HG photolysis OZ (HG-UV-OZ) and HG-Cat-OZ with UV (HG-Cat-UV-OZ). The decomposition efficiency of total organic compound (η TOC ) of HG-UV-OZ with power of UV (P UV ) of 16 W is 54% at applied dosage of ozone per volume sample m A,in = 1200 mg L -1 (reaction time t = 20 min), while that of HG-OZ without the UV irradiation is 24%. After 80 min oxidation (m A,in = 4800 mg L -1 ), the η TOC of HG-UV-OZ is as high as 94% compared to 82% of HG-OZ process. The values of η TOC for HG-Cat-OZ process with m S = 42 g are 56% and 87% at m A,in = 1200 and 4800 mg L -1 , respectively. By increasing the catalyst mass to 77 g, the η TOC for the HG-Cat-OZ process reaches 71% and 90% at m A,in = 1200 and 4800 mg L -1 , respectively. The introduction of Pt/γ-Al 2 O 3 as well as UV irradiation in the HG-OZ process can enhance the η TOC of phenol significantly, while γ-Al 2 O 3 exhibits

  13. Studies on Pyrolysis Kinetic of Newspaper Wastes in a Packed Bed Reactor: Experiments, Modeling, and Product Characterization

    Directory of Open Access Journals (Sweden)

    Aparna Sarkar

    2015-01-01

    Full Text Available Newspaper waste was pyrolysed in a 50 mm diameter and 640 mm long reactor placed in a packed bed pyrolyser from 573 K to 1173 K in nitrogen atmosphere to obtain char and pyro-oil. The newspaper sample was also pyrolysed in a thermogravimetric analyser (TGA under the same experimental conditions. The pyrolysis rate of newspaper was observed to decelerate above 673 K. A deactivation model has been attempted to explain this behaviour. The parameters of kinetic model of the reactions have been determined in the temperature range under study. The kinetic rate constants of volatile and char have been determined in the temperature range under study. The activation energies 25.69 KJ/mol, 27.73 KJ/mol, 20.73 KJ/mol and preexponential factors 7.69 min−1, 8.09 min−1, 0.853 min−1 of all products (solid reactant, volatile, and char have been determined, respectively. A deactivation model for pyrolysis of newspaper has been developed under the present study. The char and pyro-oil obtained at different pyrolysis temperatures have been characterized. The FT-IR analyses of pyro-oil have been done. The higher heating values of both pyro-products have been determined.

  14. A prediction model for the effective thermal conductivity of mono-sized pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoliang; Zheng, Jie; Chen, Hongli, E-mail: hlchen1@ustc.edu.cn

    2016-02-15

    Highlights: • One new method to couple the contact area with bed strain is developed. • The constant coefficient to correlate the effect of gas flow is determined. • This model is valid for various cases, and its advantages are showed obviously. - Abstract: A model is presented here to predict the effective thermal conductivity of porous medium packed with mono-sized spherical pebbles, and it is valid when pebbles’ size is far less than the characteristic length of porous medium just like the fusion pebble beds. In this model, the influences of parameters such as properties of pebble and gas materials, bed porosity, pebble size, gas flow, contact area, thermal radiation, contact resistance, etc. are all taken into account, and one method to couple the contact areas with bed strains is also developed and implemented preliminarily. Compared with available theoretical models, CFD numerical simulations and experimental data, this model is verified to be successful to forecast the bed effective thermal conductivity in various cases and its advantages are also showed obviously. Especially, the convection in pebble beds is focused on and a constant coefficient C to correlate the effect of gas flow is determined for the fully developed region of beds by numerical simulation, which is close to some experimental data.

  15. Deleterious Thermal Effects due to Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

    Science.gov (United States)

    Moran, Robert P.

    2013-01-01

    Reactor fuel rod surface area that is perpendicular to coolant flow direction (+S) i.e. perpendicular to the P creates areas of coolant stagnation leading to increased coolant temperatures resulting in localized changes in fluid properties. Changes in coolant fluid properties caused by minor increases in temperature lead to localized reductions in coolant mass flow rates leading to localized thermal instabilities. Reductions in coolant mass flow rates result in further increases in local temperatures exacerbating changes to coolant fluid properties leading to localized thermal runaway. Unchecked localized thermal runaway leads to localized fuel melting. Reactor designs with randomized flow paths are vulnerable to localized thermal instabilities, localized thermal runaway, and localized fuel melting.

  16. Advanced Core Design And Fuel Management For Pebble-Bed Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hans D. Gougar; Abderrafi M. Ougouag; William K. Terry

    2004-10-01

    A method for designing and optimizing recirculating pebble-bed reactor cores is presented. At the heart of the method is a new reactor physics computer code, PEBBED, which accurately and efficiently computes the neutronic and material properties of the asymptotic (equilibrium) fuel cycle. This core state is shown to be unique for a given core geometry, power level, discharge burnup, and fuel circulation policy. Fuel circulation in the pebble-bed can be described in terms of a few well?defined parameters and expressed as a recirculation matrix. The implementation of a few heat?transfer relations suitable for high-temperature gas-cooled reactors allows for the rapid estimation of thermal properties critical for safe operation. Thus, modeling and design optimization of a given pebble-bed core can be performed quickly and efficiently via the manipulation of a limited number key parameters. Automation of the optimization process is achieved by manipulation of these parameters using a genetic algorithm. The end result is an economical, passively safe, proliferation-resistant nuclear power plant.

  17. The Dynamic Behavior of Water Flowing Through Packed Bed of Different Particle Shapes and Sizes

    Directory of Open Access Journals (Sweden)

    Haneen Ahmed Jasim

    2017-12-01

    Full Text Available An experimental study was conducted on pressure drop of water flow through vertical cylindrical packed beds in turbulent region and the influence of the operating parameters on its behavior. The bed packing was made of spherical and non-spherical particles (spheres, Rasching rings and intalox saddle with aspect ratio range 3.46 D/dp 8.486 obtaining bed porosities 0.396 0.84 and Reynolds number 1217 21758. The system is consisted of 5 cm inside diameter Perspex column, 50 cm long; distilled water was pumped through the bed with flow rate 875, 1000, 1125, 1250,1375 and 1500 l/h and inlet water temperature 20, 30, 40 and 50 ˚C. The packed bed system was monitored by using LabVIEW program, were the results have been obtained from Data Acquisition Adaptor (DAQ.

  18. Investigations on a new internally-heated tubular packed-bed methanol–steam reformer

    KAUST Repository

    Nehe, Prashant

    2015-05-01

    Small-scale reformers for hydrogen production through steam reforming of methanol can provide an alternative solution to the demand of continuous supply of hydrogen gas for the operation of Proton Exchange Membrane Fuel Cells (PEMFCs). A packed-bed type reformer is one of the potential designs for such purpose. An externally heated reformer has issues of adverse lower temperature in the core of the reformer and significant heat loss to the environment thus impacting its performance. Experimental and numerical studies on a new concept of internally heated tubular packed-bed methanol-steam reformer have been reported in this paper with improved performance in terms of higher methanol conversion and reduced heat losses to surroundings. CuO/ZnO/Al2O3 is used as the catalyst for the methanol-steam reforming reaction and a rod-type electric heater at the center of the reactor is used for supplying necessary heat for endothermic steam reforming reaction. The vaporizer and the reformer unit with a constant volume catalyst bed are integrated in the annular section of a tubular reformer unit. The performance of the reformer was investigated at various operating conditions like feed rate of water-methanol mixture, mass of the catalyst and reforming temperature. The experimental and numerical results show that the methanol conversion and CO concentration increase with internal heating for a wide range of operating conditions. The developed reformer unit generates 50-80W (based on lower heating value) of hydrogen gas for applications in PEMFCs. For optimized design and operating conditions, the reformer unit produced 298sccm reformed gas containing 70% H2, 27% CO2 and 3% CO at 200-240°C which can produce a power output of 25-32W assuming 60% fuel cell efficiency and 80% of hydrogen utilization in a PEMFC. © 2015 Hydrogen Energy Publications, LLC.

  19. 3D Numerical Study of Multiphase Counter-Current Flow within a Packed Bed for Post Combustion Carbon Dioxide Capture

    Directory of Open Access Journals (Sweden)

    Li Yang

    2018-06-01

    Full Text Available The hydrodynamics within counter-current flow packed beds is of vital importance to provide insight into the design and operational parameters that may impact reactor and reaction efficiencies in processes used for post combustion CO2 capture. However, the multiphase counter-current flows in random packing used in these processes are complicated to visualize. Hence, this work aimed at developing a computational fluid dynamics (CFD model to study more precisely the complex details of flow inside a packed bed. The simulation results clearly demonstrated the development of, and changes in, liquid distributions, wetted areas, and film thickness under various gas and liquid flow rates. An increase in values of the We number led to a more uniform liquid distribution, and the flow patterns changed from droplet flow to film flow and trickle flow as the We number was increased. In contrast, an increase in gas flow rate had no significant effect on the wetted areas and liquid holdup. It was also determined that the number of liquid inlets affected flow behavior, and the liquid surface tension had an insignificant influence on pressure drop or liquid holdup; however, lower surface tension provided a larger wetted area and a thinner film. An experimental study, performed to enable comparisons between experimentally measured pressure drops and simulation-determined pressure drops, showed close correspondence and similar trends between the experimental data and the simulation data; hence, it was concluded that the simulation model was validated and could reasonably predict flow dynamics within a counter-current flow packed bed.

  20. Enzymatic production of biodiesel from waste cooking oil in a packed-bed reactor: an engineering approach to separation of hydrophilic impurities.

    Science.gov (United States)

    Hama, Shinji; Yoshida, Ayumi; Tamadani, Naoki; Noda, Hideo; Kondo, Akihiko

    2013-05-01

    An engineering approach was applied to an efficient biodiesel production from waste cooking oil. In this work, an enzymatic packed-bed reactor (PBR) was integrated with a glycerol-separating system and used successfully for methanolysis, yielding a methyl ester content of 94.3% and glycerol removal of 99.7%. In the glycerol-separating system with enhanced retention time, the effluent contained lesser amounts of glycerol and methanol than those in the unmodified system, suggesting its promising ability to remove hydrophilic impurities from the oil layer. The PBR system was also applied to oils with high acid values, in which fatty acids could be esterified and the large amount of water was extracted using the glycerol-separating system. The long-term operation demonstrated the high lipase stability affording less than 0.2% residual triglyceride in 22 batches. Therefore, the PBR system, which facilitates the separation of hydrophilic impurities, is applicable to the enzymatic biodiesel production from waste cooking oil. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Carbon Sequestration in Olivine and Basalt Powder Packed Beds.

    Science.gov (United States)

    Xiong, Wei; Wells, Rachel K; Giammar, Daniel E

    2017-02-21

    Fractures and pores in basalt could provide substantial pore volume and surface area of reactive minerals for carbonate mineral formation in geologic carbon sequestration. In many fractures solute transport will be limited to diffusion, and opposing chemical gradients that form as a result of concentration differences can lead to spatial distribution of silicate mineral dissolution and carbonate mineral precipitation. Glass tubes packed with grains of olivine or basalt with different grain sizes and compositions were used to explore the identity and spatial distribution of carbonate minerals that form in dead-end one-dimensional diffusion-limited zones that are connected to a larger reservoir of water in equilibrium with 100 bar CO 2 at 100 °C. Magnesite formed in experiments with olivine, and Mg- and Ca-bearing siderite formed in experiments with flood basalt. The spatial distribution of carbonates varied between powder packed beds with different powder sizes. Packed beds of basalt powder with large specific surface areas sequestered more carbon per unit basalt mass than powder with low surface area. The spatial location and extent of carbonate mineral formation can influence the overall ability of fractured basalt to sequester carbon.

  2. Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Weizhou, E-mail: jwz0306@126.com; Qin, Yuejiao [North University of China, Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering (China); Luo, Shuai [Virginia Polytechnic Institute and State University, Department of Civil and Environmental Engineering (United States); Feng, Zhirong; Liu, Youzhi [North University of China, Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering (China)

    2017-02-15

    Nanoscale zero-valent iron (nZVI) was continuously prepared by high-gravity reaction precipitation through a novel impinging stream-rotating packed bed (IS-RPB). Reactant solutions of FeSO{sub 4} and NaBH{sub 4} were conducted into the IS-RPB with flow rates of 60 L/h and rotating speed of 1000 r/min for the preparation of nZVI. As-prepared nZVI obtained by IS-RPB were quasi-spherical morphology and almost uniformly distributed with a particle size of 10–20 nm. The reactivity of nZVI was estimated by the degradation of 100 ml nitrobenzene (NB) with initial concentration of 250 mg/L. The optimum dosage of nZVI obtained by IS-RPB was 4.0 g/L as the NB could be completely removed within 10 min, which reduced 20% compared with nZVI obtained by stirred tank reactor (STR). The reduction of NB and production of aniline (AN) followed pseudo-first-order kinetics, and the pseudo-first-order rate constants were 0.0147 and 0.0034 s{sup −1}, respectively. Furthermore, the as-prepared nZVI using IS-RPB reactor in this work can be used within a relatively wide range pH of 1–9.

  3. Continuous preparation of nanoscale zero-valent iron using impinging stream-rotating packed bed reactor and their application in reduction of nitrobenzene

    Science.gov (United States)

    Jiao, Weizhou; Qin, Yuejiao; Luo, Shuai; Feng, Zhirong; Liu, Youzhi

    2017-02-01

    Nanoscale zero-valent iron (nZVI) was continuously prepared by high-gravity reaction precipitation through a novel impinging stream-rotating packed bed (IS-RPB). Reactant solutions of FeSO4 and NaBH4 were conducted into the IS-RPB with flow rates of 60 L/h and rotating speed of 1000 r/min for the preparation of nZVI. As-prepared nZVI obtained by IS-RPB were quasi-spherical morphology and almost uniformly distributed with a particle size of 10-20 nm. The reactivity of nZVI was estimated by the degradation of 100 ml nitrobenzene (NB) with initial concentration of 250 mg/L. The optimum dosage of nZVI obtained by IS-RPB was 4.0 g/L as the NB could be completely removed within 10 min, which reduced 20% compared with nZVI obtained by stirred tank reactor (STR). The reduction of NB and production of aniline (AN) followed pseudo-first-order kinetics, and the pseudo-first-order rate constants were 0.0147 and 0.0034 s-1, respectively. Furthermore, the as-prepared nZVI using IS-RPB reactor in this work can be used within a relatively wide range pH of 1-9.

  4. Study of the obtainment of Mo_2C by gas-solid reaction in a fixed and rotary bed reactor

    International Nuclear Information System (INIS)

    Araujo, C.P.B. de; Souza, C.P. de; Souto, M.V.M.; Barbosa, C.M.; Frota, A.V.V.M.

    2016-01-01

    Carbides' synthesis via gas-solid reaction overcomes many of the difficulties found in other processes, requiring lower temperatures and reaction times than traditional metallurgic routes, for example. In carbides' synthesis in fixed bed reactors (FB) the solid precursor is permeated by the reducing/carburizing gas stream forming a packed bed without mobility. The use of a rotary kiln reactor (RK) adds a mixing character to this process, changing its fluid-particle dynamics. In this work ammonium molybdate was subjected to carbo-reduction reaction (CH4 / H2) in both reactors under the same gas flow (15L / h) and temperature (660 ° C) for 180 minutes. Complete conversion was observed Mo2C (dp = 18.9nm modal particles sizes' distribution) in the fixed bed reactor. In the RK reactor this conversion was only partial (∼ 40%) and Mo2C and MoO3 (34nm dp = bimodal) could be observed on the produced XRD pattern. Partial conversion was attributed to the need to use higher solids loading in the reactor CR (50% higher) to avoid solids to centrifuge. (author)

  5. Ammonia, Total Reduced Sulfides, and Greenhouse Gases of Pine Chip and Corn Stover Bedding Packs.

    Science.gov (United States)

    Spiehs, Mindy J; Brown-Brandl, Tami M; Parker, David B; Miller, Daniel N; Berry, Elaine D; Wells, James E

    2016-03-01

    Bedding materials may affect air quality in livestock facilities. Our objective in this study was to compare headspace concentrations of ammonia (NH), total reduced sulfides (TRS), carbon dioxide (CO), methane (CH), and nitrous oxide (NO) when pine wood chips ( spp.) and corn stover ( L.) were mixed in various ratios (0, 10, 20, 30, 40, 60, 80, and 100% pine chips) and used as bedding with manure. Air samples were collected from the headspace of laboratory-scaled bedded manure packs weekly for 42 d. Ammonia concentrations were highest for bedded packs containing 0, 10, and 20% pine chips (equivalent to 501.7, 502.3, and 502.3 mg m, respectively) in the bedding mixture and were lowest when at least 80% pine chips were used as bedding (447.3 and 431.0 mg m, respectively for 80 and 100% pine chip bedding). The highest NH concentrations were observed at Day 28. The highest concentration of TRS was observed when 100% pine chips were used as bedding (11.4 µg m), with high concentrations occurring between Days 7 and 14, and again at Day 35. Greenhouse gases were largely unaffected by bedding material but CH and CO concentrations increased as the bedded packs aged and NO concentrations were highly variable throughout the incubation. We conclude that a mixture of bedding material that contains 30 to 40% pine chips may be the ideal combination to reduce both NH and TRS emissions. All gas concentrations increased as the bedded packs aged, suggesting that frequent cleaning of facilities would improve air quality in the barn, regardless of bedding materials used. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Root Cause Assessment of Pressure Drop Rise of a Packed Bed of Lithium Hydroxide in the International Space Station Trace Contaminant Control System

    Science.gov (United States)

    Aguilera, Tatiana; Perry, Jay L.

    2009-01-01

    The trace contaminant control system (TCCS) located in the International Space Station s (ISS) U.S. laboratory module employs physical adsorption, thermal catalytic oxidation, and chemical adsorption to remove trace chemical contamination produced by equipment offgassing and anthropogenic sources from the cabin atmosphere. The chemical adsorption stage, consisting of a packed bed of granular lithium hydroxide (LiOH), is located after the thermal catalytic oxidation stage and is designed to remove acid gas byproducts that may be formed in the upstream oxidation stage. While in service on board the ISS, the LiOH bed exhibited a change in flow resistance that leading to flow control difficulties in the TCCS. Post flight evaluation revealed LiOH granule size attrition among other changes. An experimental program was employed to investigate mechanisms hypothesized to contribute to the change in the packed bed s flow resistance. Background on the problem is summarized, including a discussion of likely mechanisms. The experimental program is described, results are presented, and implications for the future are discussed.

  7. Start-up and performance characteristics of a trickle bed reactor degrading toluene

    Directory of Open Access Journals (Sweden)

    Ondrej Misiaczek

    2007-09-01

    Full Text Available The objective of this work was to evaluate toluene degradation in a trickle bed reactor when the loading was carried out by changing the air flow rate. The biofiltration system was inoculated with a mixed microbial population, adapted to degradation of hydrophobic compounds. Polypropylene high flow rings were used as a packing material. The system was operated for a period of 50 days at empty bed residence times ranging from 106s to 13s and with a constant inlet concentration of toluene of 100 mg.m-3. The reactor showed high removal efficiency at higher contact times and increasing elimination capacity with higher air-flow rates. The highest EC value reached was 9.8 gC.m-3.h-1 at EBRT = 13s. During the experiment, the consumption of NaOH solution was also measured. No significant variation of this value was found and an average value of 3.84 mmol of NaOH per gram of consumed carbon was recorded.

  8. Cyanuric acid biodegradation by a mixed bacterial culture of Agrobacterium tumefaciens and Acinetobacter sp. in a packed bed biofilm reactor.

    Science.gov (United States)

    Galíndez-Nájera, S P; Llamas-Martínez, M A; Ruiz-Ordaz, N; Juárez-Ramírez, C; Mondragón-Parada, M E; Ahuatzi-Chacón, D; Galíndez-Mayer, J

    2009-02-01

    Cyanuric acid (1,3,5-triazine-2,4,6-triol [OOOT]) is a common biodegradation byproduct of triazinic herbicides, frequently accumulated in soils or water when supplementary carbon sources are absent. A binary bacterial culture able to degrade OOOT was selected through a continuous selection process accomplished in a chemostat fed with a mineral salt (MS) medium containing cyanuric acid as the sole carbon and nitrogen source. By sequence comparison of their 16S rDNA amplicons, bacterial strains were identified as Agrobacterium tumefaciens, and Acinetobacter sp. When the binary culture immobilized in a packed bed reactor (PBR) was fed with MS medium containing OOOT (50 mg L(-1)), its removal efficiencies were about 95%; when it was fed with OOOT plus glucose (120 mg L(-1)) as a supplementary carbon source, its removal efficiencies were closer to 100%. From sessile cells, attached to PBR porous support, or free cells present in the outflowing medium, DNA was extracted and used for Random Amplification of Polymorphic DNA analysis. Electrophoretic patterns obtained were compared to those of pure bacterial strains, a clear predominance of A. tumefaciens in PBR was observed. Although in continuous suspended cell culture, a stable binary community could be maintained, the attachment capability of A. tumefaciens represented a selective advantage over Acinetobacter sp. in the biofilm reactor, favoring its predominance in the porous stone support.

  9. Successive pretreatment and enzymatic saccharification of sugarcane bagasse in a packed bed flow-through column reactor aiming to support biorefineries.

    Science.gov (United States)

    Terán-Hilares, R; Reséndiz, A L; Martínez, R T; Silva, S S; Santos, J C

    2016-03-01

    A packed bed flow-through column reactor (PBFTCR) was used for pretreatment and subsequent enzymatic hydrolysis of sugarcane bagasse (SCB). Alkaline pretreatment was performed at 70 °C for 4h with fresh 0.3M NaOH solution or with liquor recycled from a previous pretreatment batch. Scheffersomyces stipitis NRRL-Y7124 was used for fermentation of sugars released after enzymatic hydrolysis (20 FPU g(-1) of dry SCB). The highest results for lignin removal were 61% and 52%, respectively, observed when using fresh NaOH or the first reuse of the liquor. About 50% of cellulosic and 57% of hemicellulosic fractions of pretreated SCBs were enzymatically hydrolyzed and the maximum ethanol production was 23.4 g L(-1) (ethanol yield of 0.4 gp gs(-1)), with near complete consumption of both pentoses and hexoses present in the hydrolysate during the fermentation. PBFTCR as a new alternative for SCB-biorefineries is presented, mainly considering its simple configuration and efficiency for operating with a high solid:liquid ratio. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. 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

  11. Short communication: Bacterial counts in recycled manure solids bedding replaced daily or deep packed in freestalls.

    Science.gov (United States)

    Sorter, D E; Kester, H J; Hogan, J S

    2014-05-01

    An experiment was conducted to compare bacterial counts of mastitis pathogens in deep-packed manure solids bedding with those in manure solids bedding replaced daily from mattresses. Eighteen Holstein cows were housed in 1 pen with 18 stalls. One row of 9 stalls was equipped with mattresses topped with bedding. The back one-third of these stalls toward the alleyway was covered in 25 mm of recycled manure solids, which was removed daily for the next 6 d and replaced with bedding from the brisket board and lunge space areas of stalls. The second row of 9 stalls was bedded for 3 wk with 100 to 150 mm of deep-pack recycled manure bedding from which only fecal matter was removed daily. After 3 wk, bedding treatments were changed between rows in a switchback design. Mean total gram-negative bacterial counts did not differ between treatments throughout the experiment. Coliform and Klebsiella spp. bacterial counts were lower in daily replaced bedding compared with deep pack across the experiment and on each of d 0, 1, 2, and 6. Streptococcal counts were reduced in daily replacement stalls compared with deep-pack stalls on d 0 and greater in daily replacement stalls compared with deep-pack stalls on d 1, 2, and 6. Daily replacement of recycled manure bedding from the back one-third of the stalls appeared to be an effective approach to reducing exposure to coliforms, specifically Klebsiella, but not streptococci. However, bacterial counts in bedding from both treatments were elevated throughout the trial and resulted in considerable risk for exposure to teats and development of intramammary infections. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. Experimental and Numerical Research Activity on a Packed Bed TES System

    Directory of Open Access Journals (Sweden)

    Mario Cascetta

    2016-09-01

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

  13. Tightly Coupled Multiphysics Algorithm for Pebble Bed Reactors

    International Nuclear Information System (INIS)

    Park, HyeongKae; Knoll, Dana; Gaston, Derek; Martineau, Richard

    2010-01-01

    We have developed a tightly coupled multiphysics simulation tool for the pebble-bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.

  14. Neutronic design of a Liquid Salt-cooled Pebble Bed Reactor (LSPBR)

    International Nuclear Information System (INIS)

    De Zwaan, S. J.; Boer, B.; Lathouwers, D.; Kloosterman, J. L.

    2006-01-01

    A renewed interest has been raised for liquid salt cooled nuclear reactors. The excellent heat transfer properties of liquid salt coolants provide several benefits, like lower fuel temperatures, higher coolant outlet temperatures, increased core power density and better decay heat removal. In order to benefit from the online refueling capability of a pebble bed reactor, the Liquid Salt Pebble Bed Reactor (LSPBR) is proposed. This is a high temperature pebble-bed reactor with a fuel design similar to existing HTRs, but using a liquid salt as a coolant. In this paper, the selection criteria for the liquid salt coolant are described. Based on its neutronic properties, LiF-BeF 2 (FLIBE) was selected for the LSPBR. Two designs of the LSPBR were considered: a cylindrical core and an annular core with a graphite inner reflector. Coupled neutronic-thermal hydraulic calculations were performed to obtain the steady state power distribution and the corresponding fuel temperatures. Finally, calculations were performed to investigate the decay heat removal capability in a protected loss-of-forced cooling accident. The maximum allowable power that can be produced with the LSPBR is hereby determined. (authors)

  15. Closing the Loop by Combining UASB Reactor and Reactive Bed Filetr Technology for wastewater Treatment : Modelling and Practical Approaches

    OpenAIRE

    Rodríguez-Gómez, Raúl

    2016-01-01

    A laboratory-scale upflow anaerobic sludge blanket (UASB) reactor followed by a packed bed reactor (PBR) filled with Sorbulite® in the lower part and Polonite® in the upper part was used to treat household wastewater in a 50-week experiment. A model was developed to describe the performance of the UASB reactor, including mass transfer through the film around anaerobic granules, intra-particle diffusion and bioconversion of the substrate. In a second model, a numerical expression describing th...

  16. Single and double pass solar air heaters with wire mesh as packing bed

    Energy Technology Data Exchange (ETDEWEB)

    Aldabbagh, L.B.Y.; Egelioglu, F. [Mechanical Engineering Department, Eastern Mediterranean University, Magosa, Mersin 10 (Turkey); Ilkan, M. [School of Computing and Tecnology, Eastern Mediterranean University, Magosa, Mersin 10 (Turkey)

    2010-09-15

    The thermal performances of single and double pass solar air heaters with steel wire mesh layers are used instead of a flat absorber plate are investigated experimentally. The effects of mass flow rate of air on the outlet temperature and thermal efficiency were studied. The results indicate that the efficiency increases with increasing the mass flow rate for the range of the flow rate used in this work between 0.012 and 0.038 kg/s. For the same flow rate, the efficiency of the double pass is found to be higher than the single pass by 34-45%. Moreover, the maximum efficiencies obtained for the single and the double pass air collectors are 45.93 and 83.65% respectively for the mass flow rate of 0.038 kg/s. Comparison of the results of a packed bed collector with those of a conventional collector shows a substantial enhancement in the thermal efficiency. (author)

  17. Coupled electrochemical thermal modelling of a novel Li-ion battery pack thermal management system

    International Nuclear Information System (INIS)

    Basu, Suman; Hariharan, Krishnan S.; Kolake, Subramanya Mayya; Song, Taewon; Sohn, Dong Kee; Yeo, Taejung

    2016-01-01

    Highlights: • Three-dimensional electrochemical thermal model of Li-ion battery pack using computational fluid dynamics (CFD). • Novel pack design for compact liquid cooling based thermal management system. • Simple temperature estimation algorithm for the cells in the pack using the results from the model. • Sensitivity of the thermal performance to contact resistance has been investigated. - Abstract: Thermal management system is of critical importance for a Li-ion battery pack, as high performance and long battery pack life can be simultaneously achieved when operated within a narrow range of temperature around the room temperature. An efficient thermal management system is required to keep the battery temperature in this range, despite widely varying operating conditions. A novel liquid coolant based thermal management system, for 18,650 battery pack has been introduced herein. This system is designed to be compact and economical without compromising safety. A coupled three-dimensional (3D) electrochemical thermal model is constructed for the proposed Li-ion battery pack. The model is used to evaluate the effects of different operating conditions like coolant flow-rate and discharge current on the pack temperature. Contact resistance is found to have the strongest impact on the thermal performance of the pack. From the numerical solution, a simple and novel temperature correlation of predicting the temperatures of all the individual cells given the temperature measurement of one cell is devised and validated with experimental results. Such coefficients have great potential of reducing the sensor requirement and complexity in a large Li-ion battery pack, typical of an electric vehicle.

  18. Thermal conductivity and tritium retention in Li2O and Li2ZrO3

    International Nuclear Information System (INIS)

    Billone, M.C.

    1997-01-01

    Lithium oxide (Li 2 O) and lithium zirconate (Li 2 ZrO 3 ) are promising ceramic breeder materials for fusion reactor blankets. The thermal and tritium transport databases for these materials are reviewed. Algorithms are presented for predicting both the temperature distribution and the retained tritium profile across sintered-product and pebble-bed regions. Sample design calculations are also performed to demonstrate the relative advantages of each breeder ceramic. For Li 2 O, the thermal conductivity of sintered-product material has been measured over a wide range of temperatures and densities. Data are also available for the effective thermal conductivity of a pebble bed (in atmospheric helium) with 55% packing fraction for the 5-mm-diameter/75%-dense pebbles. Similar results are available for sintered-product and pebble-bed (60% packing fraction for 1.2-mm-diameter/80%-dense pebbles in atmospheric He) Li 2 ZrO 3 . Hall and Martin model predictions are in reasonable agreement with both sets of pebble bed data. Thus, the databases and calculational algorithms are well established for performing thermal analyses. 15 refs., 5 figs

  19. Mathematical modeling of high-rate Anammox UASB reactor based on granular packing patterns

    International Nuclear Information System (INIS)

    Tang, Chong-Jian; He, Rui; Zheng, Ping; Chai, Li-Yuan; Min, Xiao-Bo

    2013-01-01

    Highlights: ► A novel model was conducted to estimate volumetric nitrogen conversion rates. ► The packing patterns of the granules in Anammox reactor are investigated. ► The simple cubic packing pattern was simulated in high-rate Anammox UASB reactor. ► Operational strategies concerning sludge concentration were proposed by the modeling. -- Abstract: A novel mathematical model was developed to estimate the volumetric nitrogen conversion rates of a high-rate Anammox UASB reactor based on the packing patterns of granular sludge. A series of relationships among granular packing density, sludge concentration, hydraulic retention time and volumetric conversion rate were constructed to correlate Anammox reactor performance with granular packing patterns. It was suggested that the Anammox granules packed as the equivalent simple cubic pattern in high-rate UASB reactor with packing density of 50–55%, which not only accommodated a high concentration of sludge inside the reactor, but also provided large pore volume, thus prolonging the actual substrate conversion time. Results also indicated that it was necessary to improve Anammox reactor performance by enhancing substrate loading when sludge concentration was higher than 37.8 gVSS/L. The established model was carefully calibrated and verified, and it well simulated the performance of granule-based high-rate Anammox UASB reactor

  20. Mathematical modeling of high-rate Anammox UASB reactor based on granular packing patterns

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Chong-Jian, E-mail: chjtangzju@yahoo.com.cn [Department of Environmental Engineering, School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Changsha 410083 (China); He, Rui; Zheng, Ping [Department of Environmental Engineering, Zhejiang University, Zijingang Campus, Hangzhou 310058 (China); Chai, Li-Yuan; Min, Xiao-Bo [Department of Environmental Engineering, School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Changsha 410083 (China)

    2013-04-15

    Highlights: ► A novel model was conducted to estimate volumetric nitrogen conversion rates. ► The packing patterns of the granules in Anammox reactor are investigated. ► The simple cubic packing pattern was simulated in high-rate Anammox UASB reactor. ► Operational strategies concerning sludge concentration were proposed by the modeling. -- Abstract: A novel mathematical model was developed to estimate the volumetric nitrogen conversion rates of a high-rate Anammox UASB reactor based on the packing patterns of granular sludge. A series of relationships among granular packing density, sludge concentration, hydraulic retention time and volumetric conversion rate were constructed to correlate Anammox reactor performance with granular packing patterns. It was suggested that the Anammox granules packed as the equivalent simple cubic pattern in high-rate UASB reactor with packing density of 50–55%, which not only accommodated a high concentration of sludge inside the reactor, but also provided large pore volume, thus prolonging the actual substrate conversion time. Results also indicated that it was necessary to improve Anammox reactor performance by enhancing substrate loading when sludge concentration was higher than 37.8 gVSS/L. The established model was carefully calibrated and verified, and it well simulated the performance of granule-based high-rate Anammox UASB reactor.

  1. Continuous D-tagatose production by immobilized thermostable L-arabinose isomerase in a packed-bed bioreactor.

    Science.gov (United States)

    Ryu, Se-Ah; Kim, Chang Sup; Kim, Hye-Jung; Baek, Dae Heoun; Oh, Deok-Kun

    2003-01-01

    D-Tagatose was continuously produced using thermostable L-arabinose isomerase immobilized in alginate with D-galactose solution in a packed-bed bioreactor. Bead size, L/D (length/diameter) of reactor, dilution rate, total loaded enzyme amount, and substrate concentration were found to be optimal at 0.8 mm, 520/7 mm, 0.375 h(-1), 5.65 units, and 300 g/L, respectively. Under these conditions, the bioreactor produced about 145 g/L tagatose with an average productivity of 54 g tagatose/L x h and an average conversion yield of 48% (w/w). Operational stability of the immobilized enzyme was demonstrated, with a tagatose production half-life of 24 days.

  2. Performance of an enzymatic packed bed reactor running on babassu oil to yield fatty ethyl esters (FAEE in a solvent-free system

    Directory of Open Access Journals (Sweden)

    Aline Simões

    2015-06-01

    Full Text Available The transesterification reaction of babassu oil with ethanol mediated by Burkholderia cepacia lipase immobilized on SiO2-PVA composite was assessed in a packed bed reactor running in the continuous mode. Experiments were performed in a solvent-free system at 50 °C. The performance of the reactor (14 mm ×210 mm was evaluated using babassu oil and ethanol at two molar ratios of 1:7 and 1:12, respectively, and operational limits in terms of substrate flow rate were determined. The system’s performance was quantified for different flow rates corresponding to space times between 7 and 13 h. Under each condition, the impact of the space time on the ethyl esters formation, the transesterification yield and productivity were determined. The oil to ethanol molar ratio was found as a critical parameter in the conversion of babassu oil into the correspondent ethyl esters. The highest transesterification yield of 96.0 ± 0.9% and productivity of 41.1 ± 1.6 mgester gcatalyst-1h-1 were achieved at the oil to ethanol molar ratio of 1:12 and for space times equal or higher than 11 h. Moreover, the immobilized lipase was found stable with respect to its catalytic characteristics, exhibiting a half-life of 32 d.

  3. Simple models for the continuous aerobic biodegradation of phenol in a packed bed reactor

    Directory of Open Access Journals (Sweden)

    Andrew Mark Gerrard

    2006-07-01

    Full Text Available This paper proposes the use of a preliminary, phenol removal step to reduce peak loads arriving at a conventional effluent plant. A packed bed reactor (PBR using polyurethane foam, porous glass and also cocoa fibres as the inert support material was used. Experiments have been carried out where the flow-rates, plus inlet and outlet phenol concentrations were measured. A simple, plug-flow model is proposed to represent the results. Zero, first order, Monod and inhibited kinetics rate equations were evaluated. It was found that the Monod model gave the best fit to the experimental data and allowed linear graphs to be plotted. The Monod saturation constant, K, is approximately 50 g m-3, and ka is around 900 s-1.Este artigo propõe o uso de uma etapa preliminar de remoção de fenol para redução de picos de carga na entrada de sistemas convencionais de tratamento de efluentes. Um reator de leito fixo (RLF foi usado, tendo como suportes inertes espuma de poliuretano, vidro poroso e também fibras de coco. Nos experimentos foram controladas a vazão e as concentrações de fenol de entrada e saída. Um simples modelo plug-flow é proposto para representar os resultados. Cinéticas de zero e primeira ordens, Monod e de inibição foram avaliadas. Foi verificado que o modelo de Monod foi o que melhor se ajustou aos dados experimentais, permitindo que gráficos lineares fossem traçados. A constante saturação de Monod, K, é de aproximadamente 50 g m-3 e ka em torno de 900 s-1.

  4. Evolution of Particle Bed Reactor Fuel

    Science.gov (United States)

    Jensen, Russell R.; Evans, Robert S.; Husser, Dewayne L.; Kerr, John M.

    1994-07-01

    To realize the potential performance advantages inherent in a particle bed reactor (PBR) for nuclear thermal propulsion (NTP) applications, high performance particle fuel is required. This fuel must operate safely and without failure at high temperature in high pressure, flowing hydrogen propellant. The mixed mean outlet temperature of the propellant is an important characteristic of PBR performance. This temperature is also a critical parameter for fuel particle design because it dictates the required maximum fuel operating temperature. In this paper, the evolution in PBR fuel form to achieve higher operating temperatures is discussed and the potential thermal performance of the different fuel types is evaluated. It is shown that the optimum fuel type for operation under the demanding conditions in a PBR is a coated, solid carbide particle.

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

    Directory of Open Access Journals (Sweden)

    NEVENKA BOSKOVIC-VRAGOLOVIC

    2005-11-01

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

  6. Minimum Energy Dissipation under Cocurrent Flow in Packed Beds

    Czech Academy of Sciences Publication Activity Database

    Akramov, T.A.; Stavárek, Petr; Jiřičný, Vladimír; Staněk, Vladimír

    2011-01-01

    Roč. 50, č. 18 (2011), s. 10824-10832 ISSN 0888-5885 R&D Projects: GA ČR GA104/09/0880 Institutional research plan: CEZ:AV0Z40720504 Keywords : energy dissipation * current flow * packed bed Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.237, year: 2011

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  8. Study of Co-Current and Counter-Current Gas-Liquid Two-Phase Flow Through Packed Bed in Microgravity

    Science.gov (United States)

    Revankar, Shripad T.

    2002-11-01

    The main goal of the project is to obtain new experimental data and development of models on the co-current and counter-current gas-liquid two-phase flow through a packed bed in microgravity and characterize the flow regime transition, pressure drop, void and interfacial area distribution, and liquid hold up. Experimental data will be obtained for earth gravity and microgravity conditions. Models will be developed for the prediction of flow regime transition, void fraction distribution and interfacial area concentration, which are key parameters to characterize the packed bed performance. Thus the specific objectives of the proposed research are to: (1) Develop experiments for the study of the gas liquid two-phase flow through the packed bed with three different flow combinations: co-current down flow, co-current upflow and counter current flow. (2) Develop pore scale and bed scale two-phase instrumentation for measurement of flow regime transition, void distribution and gas-liquid interfacial area concentration in the packed bed. (3) Obtain database on flow regime transition, pressure drop, void distribution, interfacial area concentration and liquid hold up as a function of bed characteristics such as bed particle size, porosity, and liquid properties such as viscosity and surface tension. (4) Develop mathematical model for flow regime transition, void fraction distribution and interfacial area concentration for co-current gas-liquid flow through the porous bed in gravity and micro gravity conditions.(4) Develop mathematical model for the flooding phenomena in counter-current gas-liquid flow through the porous bed in gravity and micro gravity conditions. The present proposal addresses the most important topic of HEDS-specific microgravity fluid physics research identified by NASA 's one of the strategic enterprises, OBPR Enterprise. The proposed project is well defined and makes efficient use of the ground-based parabolic flight research aircraft facility. The

  9. Acidolysis of terebinth fruit oil with palmitic and caprylic acids in a recirculating packed bed reactor: optimization using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Koçak, D.; Keskin, H.; Fadiloglu, S.; Gögüs, F.

    2016-07-01

    The acidolysis reaction of terebinth fruit oil with caprylic and palmitic acid has been investigated. The reaction was catalyzed by lipase (Lipozyme IM from Rhizomucormiehei) and carried out in recirculating packed bed reactor. The effects of reaction parameters have been analyzed using response surface methodology. Reaction time (3.5–6.5 h), enzyme load (10–20%), substrate flow rate (4–8 mL·min−1 ) and substrate mole ratios (Terebinth oil : Palmitic acid : Caprylic acid, 1:1.83:1.22–1:3.07:2.05) were evaluated. The optimum reaction conditions were 5.9 h reaction time, 10% enzyme load, 4 mL·min−1 substrate flow rate and 1:3.10:2.07 substrate mole ratio. The structured lipid obtained at these optimum conditions had 52.23% desired triacylglycerols and a lower caloric value than that of terebinth fruit oil. The melting characteristics and microstructure of the structured lipid were similar to those of commercial margarine fat extracts. The results showed that the structured lipid had the highest oxidative stability among the studied fats. (Author)

  10. Freezing process in unsaturated packed beds; Fuhowa ryushi sonai ni okeru suibun toketsu

    Energy Technology Data Exchange (ETDEWEB)

    Akahori, M; Aoki, K; Hattori, M [Nagaoka University of Technology, Niigata (Japan); Tani, T [Oji Paper Co. Ltd., Tokyo (Japan)

    1998-04-25

    The freezing process in unsaturated packed beds has been investigated experimentally and theoretically. Water transport to the frozen front plays an important part on freezing. The rate of the absorption of water into frozen layer depended on the freezing heat flux and the water saturation at the freezing front. As a result, ice content in the frozen layer was related to the rate of the absorption of water and the freezing heat flux. A one-dimensional freezing model in unsaturated packed beds has been presented, accounting for the water transport. The predicted water saturation and temperature distributions in the body and the thickness of frozen layer were compared with the experimental results using a porous bed composed of glass beads. 12 refs., 10 figs., 1 tab.

  11. Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

    Science.gov (United States)

    Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

    2009-02-01

    Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-15

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

  14. Fixed-bed Reactor Dynamics and Control - A Review

    DEFF Research Database (Denmark)

    Jørgensen, S. B.

    1986-01-01

    The industrial diversity of fixed bed reactors offers a challenging and relevant set of control problems. These intricate problems arise due to the rather complex dynamics of fixed bed reactors and to the complexity of actual reactor configurations. Many of these control problems are nonlinear...... and multi-variable. During the last decade fixed bed reactor control strategies have been proposed and investigated experimentally. This paper reviews research on these complex control problems with an emphasis upon solutions which have been demon-strated to work in the laboratory and hold promise...

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

    Czech Academy of Sciences Publication Activity Database

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

    2001-01-01

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

  16. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  17. Random detailed model for probabilistic neutronic calculation in pebble bed Very High Temperature Reactors

    International Nuclear Information System (INIS)

    Perez Curbelo, J.; Rosales, J.; Garcia, L.; Garcia, C.; Brayner, C.

    2013-01-01

    The pebble bed nuclear reactor is one of the main candidates for the next generation of nuclear power plants. In pebble bed type HTRs, the fuel is contained within graphite pebbles in the form of TRISO particles, which form a randomly packed bed inside a graphite-walled cylindrical cavity. Pebble bed reactors (PBR) offer the opportunity to meet the sustainability requirements, such as nuclear safety, economic competitiveness, proliferation resistance and a minimal production of radioactive waste. In order to simulate PBRs correctly, the double heterogeneity of the system must be considered. It consists on randomly located pebbles into the core and TRISO particles into the fuel pebbles. These features are often neglected due to the difficulty to model with MCPN code. The main reason is that there is a limited number of cells and surfaces to be defined. In this study, a computational tool which allows getting a new geometrical model of fuel pebbles for neutronic calculations with MCNPX code, was developed. The heterogeneity of system is considered, and also the randomly located TRISO particles inside the pebble. Four proposed fuel pebble models were compared regarding their effective multiplication factor and energy liberation profiles. Such models are: Homogeneous Pebble, Five Zone Homogeneous Pebble, Detailed Geometry, and Randomly Detailed Geometry. (Author)

  18. 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.

  19. Biodegradation of 4-bromophenol by Arthrobacter chlorophenolicus A6T in a newly designed packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Ghosh, Pranab Kumar; Pakshirajan, Kannan

    2013-02-01

    Bromophenol is listed as a priority pollutant by the U.S. EPA. However, there has been no report on the removal of bromophenol in any biological system that is operated in a continuous mode. The efficiency of Arthrobacter chlorophenolicus A6(T) on the biodegradation of 4-bromophenol (4-BP) in a newly designed packed bed reactor (PBR) was evaluated with different influent 4-BP concentrations between 400 mg l(-1) and 1200 mg l(-1) and hydraulic retention times (HRTs) between 24 h and 7.5 h. The response of the PBR to 4-BP shock loadings was also tested, and the bioreactor was found to adequately handle these shock loadings. The percentage of effluent toxicity in the PBR was tested using mixed microbial consortia as the test species; this experiment was performed using a 4-BP influent concentration of 1200 mg l(-1) and HRTs between 24 h and 7.5 h. A maximal 98% effluent toxicity removal was achieved when the PBR was operated at an HRT of 24 h. In the present study, 4-BP was used as the sole source of carbon and energy, and the complete removal of 4-BP was achieved with 4-BP loading rates of up to 2277 mg l(-1) day(-1). Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  20. Drying kinetics characteristic of Indonesia lignite coal (IBC) using lab scale fixed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kang, TaeJin; Jeon, DoMan; Namkung, Hueon; Jang, DongHa; Jeon, Youngshin; Kim, Hyungtaek [Ajou Univ., Suwon (Korea, Republic of). Div. of Energy Systems Research

    2013-07-01

    Recent instability of energy market arouse a lot of interest about coal which has a tremendous amount of proven coal reserves worldwide. South Korea hold the second rank by importing 80 million tons of coal in 2007 following by Japan. Among various coals, there is disused coal. It's called Low Rank Coal (LRC). Drying process has to be preceded before being utilized as power plant. In this study, drying kinetics of LRC is induced by using a fixed bed reactor. The drying kinetics was deduced from particle size, the inlet gas temperature, the drying time, the gas velocity, and the L/D ratio. The consideration on Reynold's number was taken for correction of gas velocity, particle size, and the L/D ratio was taken for correction packing height of coal. It can be found that active drying of free water and phase boundary reaction is suitable mechanism through the fixed bed reactor experiments.

  1. Using crosslinkable diacetylene phospholipids to construct two-dimensional packed beds in supported lipid bilayer separation platforms

    Directory of Open Access Journals (Sweden)

    Shu-Kai Hu, Sheng-Wen Hsiao, Hsun-Yen Mao, Ya-Ming Chen, Yung Chang and Ling Chao

    2013-01-01

    Full Text Available Separating and purifying cell membrane-associated biomolecules has been a challenge owing to their amphiphilic property. Taking these species out of their native lipid membrane environment usually results in biomolecule degradation. One of the new directions is to use supported lipid bilayer (SLB platforms to separate the membrane species while they are protected in their native environment. Here we used a type of crosslinkable diacetylene phospholipids, diynePC (1,2-bis(10,12-tricosadiynoyl-sn-glycero-3-phosphocholine, as a packed material to create a 'two-dimensional (2D packed bed' in a SLB platform. After the diynePC SLB is exposed to UV light, some of the diynePC lipids in the SLB can crosslink and the non-crosslinked monomer lipids can be washed away, leaving a 2D porous solid matrix. We incorporated the lipid vesicle deposition method with a microfluidic device to pattern the location of the packed-bed region and the feed region with species to be separated in a SLB platform. Our atomic force microscopy result shows that the nano-scaled structure density of the '2D packed bed' can be tuned by the UV dose applied to the diynePC membrane. When the model membrane biomolecules were forced to transport through the packed-bed region, their concentration front velocities were found to decrease linearly with the UV dose, indicating the successful creation of packed obstacles in these 2D lipid membrane separation platforms.

  2. Improvement for the design of packed moving bed adsorption column

    International Nuclear Information System (INIS)

    Xiao Wei

    2014-01-01

    The problems needed to pay attention to in the physical design of packed moving bed adsorption column were presented. The design of key parts such as the inlet and outlet of liquid phase and gas phase were improved. The expected effect was achieved by the improvement. (author)

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

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-15

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

  5. The thermal denigration in fluid-bed to make uranyl product

    International Nuclear Information System (INIS)

    Ma Zhenrong; Cui Yulin; Zhu Changbing; Fan Chuanyong; Liu Yanfeng

    2010-01-01

    Nuclear fuel reprocessing plant used the thermal denigration to high concentration of uranyl nitrate solution in fluid-bed to make uranyl product. First the uranyl nitrate solution were concentrated in evaporator, into 300 gU/L, 600 gU/L, 750 gU/L and 1000 gU/L.When the fluid-bed was in good fluidity state at 320 degree C, the solution was sprayed all over the surface of the fine crystal seeds through the dual-channel air-blast nozzles to make new crystal seed and to make them grow up. The denigration reaction occurred when the internal temperature of the fluid-bed was kept at about 300 degree C by the outside and inside heat apparatus. The product were transported crossing the valve and spiral transfer to pack. The tail gas was purified and discharged. Through the fluid-bed's running, the variation discipline of temperature and the pressure, the effect curve of the quality of product accumulated to pressure drop were determined. At the same time, the gentrification temperature, the distributed heat and the transfer mode were tested. (authors)

  6. Deuterium exchange reaction between hydrogen and water in a trickle-bed column packed with novel catalysts

    International Nuclear Information System (INIS)

    Ahn, D. H.; Baek, S. W.; Lee, H. S.; Kim, K. R.; Kang, H. S.; Lee, S. H.; Jeong, H. S.

    1998-01-01

    The activity of a novel catalyst (Pt/SDBC) for deuterium exchange reaction between water and hydrogen streams in a trickle bed was measured. The performance of the catalyst was compared with a commercial catalyst with same metal content. The catalytic activity for the bed of wet-proofed catalyst diluted with hydrophillic packing material also measured. The Pt/SDBC catalyst shows higher activity in the liquid phase reaction than the commercial catalyst as measured in the vapor phase reaction. The performance for 50% dilution of the Pt/SDBC catalyst bed with hydrophillic packing material is better than that of the 100% bed due to more liquid holdup and better water distribution

  7. Volatile Removal Assembly Flight Experiment and KC-135 Packed Bed Experiment: Results and Lessons Learned

    Science.gov (United States)

    Holder, Donald W.; Parker, David

    2000-01-01

    The Volatile Removal Assembly (VRA) is a high temperature catalytic oxidation process that will be used as the final treatment for recycled water aboard the International Space Station (ISS). The multiphase nature of the process had raised concerns as to the performance of the VRA in a microgravity environment. To address these concerns, two experiments were designed. The VRA Flight Experiment (VRAFE) was designed to test a full size VRA under controlled conditions in microgravity aboard the SPACEHAB module and in a 1 -g environment and compare the performance results. The second experiment relied on visualization of two-phase flow through small column packed beds and was designed to fly aboard NASA's microgravity test bed plane (KC-135). The objective of the KC-135 experiment was to understand the two-phase fluid flow distribution in a packed bed in microgravity. On Space Transportation System (STS) flight 96 (May 1999), the VRA FE was successfully operated and in June 1999 the KC-135 packed bed testing was completed. This paper provides an overview of the experiments and a summary of the results and findings.

  8. Modelling heat transfer during flow through a random packed bed of spheres

    Science.gov (United States)

    Burström, Per E. C.; Frishfelds, Vilnis; Ljung, Anna-Lena; Lundström, T. Staffan; Marjavaara, B. Daniel

    2018-04-01

    Heat transfer in a random packed bed of monosized iron ore pellets is modelled with both a discrete three-dimensional system of spheres and a continuous Computational Fluid Dynamics (CFD) model. Results show a good agreement between the two models for average values over a cross section of the bed for an even temperature profiles at the inlet. The advantage with the discrete model is that it captures local effects such as decreased heat transfer in sections with low speed. The disadvantage is that it is computationally heavy for larger systems of pellets. If averaged values are sufficient, the CFD model is an attractive alternative that is easy to couple to the physics up- and downstream the packed bed. The good agreement between the discrete and continuous model furthermore indicates that the discrete model may be used also on non-Stokian flow in the transitional region between laminar and turbulent flow, as turbulent effects show little influence of the overall heat transfer rates in the continuous model.

  9. A parametric study of powder holdups in a packed bed under ...

    African Journals Online (AJOL)

    Nafiisah

    Packed bed, turbulent flow, mathematical modelling, decreasing ..... The vertical gauge pressure distribution, at a distance of 0.06 m away from the tuyere ... fines from these locations as the interactive forces are more than the drag forces. It.

  10. Multi-Node Thermal System Model for Lithium-Ion Battery Packs: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Ying; Smith, Kandler; Wood, Eric; Pesaran, Ahmad

    2015-09-14

    Temperature is one of the main factors that controls the degradation in lithium ion batteries. Accurate knowledge and control of cell temperatures in a pack helps the battery management system (BMS) to maximize cell utilization and ensure pack safety and service life. In a pack with arrays of cells, a cells temperature is not only affected by its own thermal characteristics but also by its neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model, which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs. neighbors, the cooling system and pack configuration, which increase the noise level and the complexity of cell temperatures prediction. This work proposes to model lithium ion packs thermal behavior using a multi-node thermal network model, which predicts the cell temperatures by zones. The model was parametrized and validated using commercial lithium-ion battery packs.

  11. Modelling of thermal and mechanical behaviour of pebble beds

    International Nuclear Information System (INIS)

    Boccaccini, L.V.; Buehler, L.; Hermsmeyer, S.; Wolf, F.

    2001-01-01

    FZK (Forshungzentrum Karlsruhe) is developing a Helium Cooled Pebble Bed (HCPB) Blanket Concept for fusion power reactors based on the use of ceramic breeder materials and beryllium multiplier in the form of pebble beds. The design of such a blanket requires models and computer codes describing the thermal-mechanical behavior of pebble beds to evaluate the temperatures, stresses, deformations and mechanical interactions between pebble beds and the structure with required accuracy and reliability. The objective to describe the beginning of life condition for the HCPB blanket seems near to be reached. Mechanical models that describe the thermo-mechanical behavior of granular materials used in form of pebble beds are implemented in a commercial structure code. These models have been calibrated using the results of a large series of dedicated experiments. The modeling work is practically concluded for ceramic breeder; it will be carried on in the next year for beryllium to obtain the required correlations for creep and the thermal conductivity. The difficulties for application in large components (such as the HCPB blanket) are the limitations of the present commercial codes to manage such a set of constitutive equations under complex load conditions and large mesh number. The further objective is to model the thermal cycles during operation; the present correlations have to be adapted for the release phase. A complete description of the blanket behavior during irradiation is at the present out of our capability; this objective requires an extensive R and D program that at the present is only at the beginning. (Y.Tanaka)

  12. Adsorption of zinc ions on bone char using helical coil-packed bed columns and its mass transfer modeling

    DEFF Research Database (Denmark)

    Moreno-Pérez, J.; Bonilla-Petriciolet, A.; Rojas-Mayorga, C. K.

    2016-01-01

    This study reports the assessment of helical coil-packed bed columns for Zn2+ adsorption on bone char. Zn2+ adsorption breakthrough curves have been obtained using helical coil columns with different characteristics and a comparison has been conducted with respect to the results of straight fixed-bed...... columns. Results showed that the helical coil adsorption columns may offer an equivalent removal performance than that obtained for the traditional packed bed columns but using a compact structure. However, the coil diameter, number of turns, and feed flow appear to be crucial parameters for obtaining...... the best performance in this packed-bed geometry. A mass transfer model for a mobile fluid flowing through a porous media was used for fitting and predicting the Zn2+ breakthrough curves in helical coil bed columns. Results of adsorbent physicochemical characterization showed that Zn2+ adsorption on bone...

  13. New proposition on performance evaluation of hydrophobic Pt catalyst packed in trickle bed

    International Nuclear Information System (INIS)

    Shimizu, Masami; Kitamoto, Asashi; Takashima, Yoichi.

    1983-01-01

    On the evaluation of the performance of the hydrophobic Pt catalyst packed in the trickle-bed test column, the conventionally defined (Ksub(y)a) and the newly defined (Ksub(f))sub (G) are compared with each other as a measure of the overall D-transfer coefficient. The value of (Ksub(y)a) varies in a wide range in accordance with the length of the test column. On the other hand (Ksub(f))sub (G sub (l = L)) has a finite value in the test column longer than about 0.5 m. By considering the values of ksub(g) and ksub(l) which are the constituents of (Ksub(f))sub (G), it is possible to improve the hydrophobic Pt catalyst trickle bed and to design the H 2 /H 2 O-isotopic exchange trickle-bed column packed with this catalyst. (author)

  14. Engineering aspects of fluidized bed reactor operation applied to lactase treatment of whole whey

    Energy Technology Data Exchange (ETDEWEB)

    Metzdorf, C; Fauquex, P F; Flaschel, E; Renken, A

    1985-01-01

    An interesting possibility for the use of lactoserum in human nutrition is the hydrolysis of lactose to glucose and galactose, sugars which exhibit a better digestibility, a higher solubility, and which have a greater sweetening power than lactose. The hydrolysis is catalyzed by an enzyme, the ..beta..-galactosidase which, due to its high price, must be used continuously, preferentially in immobilized form. The enzyme used for these studies has been immobilized on silica gel precoated with chitosan. When whole whey or partially deproteinized whey is treated, a fluidized bed reactor seems to be the most appropriate to circumvent problems with protein adsorption and reactor plugging. However the fluidization of fine particles with a small density difference between the solid and the liquid may give rise to stability problems. In order to prevent unstable operation of the fluidized bed, the reactor has been equipped with special internals. They impose a radial distribution of the liquid and the solid phase and increase the linear velocity required to achieve a given expansion by a factor of five. Besides the resulting high solids content, the back-mixing of the liquid decreases significantly when static mixer-packings are used.

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

    International Nuclear Information System (INIS)

    Almeida, Lucilla C.; Su, Jian

    2015-01-01

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

  16. Process for the exchange of hydrogen isotopes using a catalyst packed bed assembly

    International Nuclear Information System (INIS)

    Butler, J.P.; den Hartog, J.; Molson, F.W.R.

    1978-01-01

    A process for the exchange of hydrogen isotopes between streams of gaseous hydrogen and liquid water is described, wherein the streams of liquid water and gaseous hydrogen are simultaneously brought into contact with one another and a catalyst packed bed assembly while at a temperature in the range 273 0 to 573 0 K. The catalyst packed bed assembly may be composed of discrete carrier bodies of e.g. ceramics, metals, fibrous materials or synthetic plastics with catalytically active metal crystallites selected from Group VIII of the Periodic Table, partially enclosed in and bonded to the carrier bodies by a water repellent, water vapor and hydrogen gas permeable, porous, polymeric material, and discrete packing bodies having an exterior surface which is substantially hydrophilic and relatively noncatalytically active with regard to hydrogen isotope exchange between hydrogen gas and water vapor to that of the catalyst bodies

  17. Pressure drop in packed beds of spherical particles at ambient and elevated air temperatures

    Directory of Open Access Journals (Sweden)

    Pešić Radojica

    2015-01-01

    Full Text Available The aim of this work was the experimental investigation of the particle friction factor for air flow through packed bed of particles at ambient and elevated temperatures. The experiments were performed by measuring the pressure drop across the packed bed, heated to the desired temperature by hot air. Glass spherical particles of seven different diameters were used. The temperature range of the air flowing through the packed bed was from 20ºC to 350ºC and the bed voidages were from 0.3574 to 0.4303. The obtained results were correlated using a number of available literature correlations. The overall best fit of all of the experimental data was obtained using Ergun [1] equation, with mean absolute deviation of 10.90%. Ergun`s equation gave somewhat better results in correlating the data at ambient temperature with mean absolute deviation of 9.77%, while correlation of the data at elevated temperatures gave mean absolute deviation of 12.38%. The vast majority of the correlations used gave better results when applied to ambient temperature data than to the data at elevated temperatures. Based on the results obtained, Ergun [1] equation is proposed for friction factor calculation both at ambient and at elevated temperatures. [Projekat Ministarstva nauke Republike Srbije, br. ON172022

  18. Particle Bed Reactor engine technology

    Science.gov (United States)

    Sandler, S.; Feddersen, R.

    1992-03-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology.

  19. Particle Bed Reactor engine technology

    International Nuclear Information System (INIS)

    Sandler, S.; Feddersen, R.

    1992-01-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology. 4 refs

  20. Pebble bed blanket design for deuterium burning tandem mirror reactors

    International Nuclear Information System (INIS)

    Grotz, S.P.; Dhir, V.K.

    1983-01-01

    The UCLA tandem mirror reactor, SATYR, was developed around the capability of tandem mirrors with thermal barriers to burn deuterium at reasonable efficiency levels. The pebble bed concept has been incorporated into our blanket design for the following reasons: 1) Large area-to-volume ratio for purposes of heat removal; 2) Large volume of structure for high thermal capacity thus increasing the safety margin during off-normal incidents; 3) Relatively inexpensive manufacturing costs because of large acceptable tolerances and lack of exotic materials (i.e., lithium). A simplified stress analysis of the blanket module was performed to optimize and simplify the design. The pre-specified stress intensity limitations used were based upon a 30-year predicted lifetime for each module. Along with stress analysis of the vessel a detailed thermal hydraulic analysis of the pebble bed has been completed. Parameters affecting the pebble bed design are fluidization velocity, pressure drop, heat transfer coefficient, thermally induced stress in the spheres and spatial variation of the power density. Although reasonable gross thermal efficiencies of the 2 designs has been achieved (28% for H 2 O and 39% for He) the high net recirculating power fraction for heating and neutral beams results in relatively low net plant efficiencies (21% and 27%). The results show that a blanket can be designed with good thermal efficiency and a relative-ly simple configuration. However, application of this concept to the high Q deuterium-tritium fuel cycle would have difficulties resulting from the need for continuous removal of the tritium. (orig./HP)

  1. Electrodeposition of copper from a copper sulfate solution using a packed-bed continuous-recirculation flow reactor at high applied electric current

    Directory of Open Access Journals (Sweden)

    Meshaal F. Alebrahim

    2015-09-01

    Full Text Available The purpose of this study is mainly to investigate the performance of a packed-bed continuous-recirculation flow reactor at high applied electric current in removing copper, Cu(II, from simulated electrolyte by electrodeposition. The effects of pHo, circulation rate of flow, initial copper concentration, intensity of the applied current and the method of application of electric current, as to have a constant value during all the time of electrolysis or to be decreased with time, on copper electrodeposition and current efficiency are revealed. The results showed that the increase in pH (provided not lead to the deposition of Cu(OH2, initial concentration of the copper and flow rate increased the electrodeposition of copper as well as improved current efficiency. However, increasing intensity of the applied electric current led to an increase in the electrodeposition of copper and decreased electrical efficiency. It was also observed that reducing the intensity of applied electric current with time during the electrolysis process while maintaining other operating variables constant led to a significant reduction in the consumption of electrical energy used in the process of copper removal by electrodeposition; a reduction of 41.6% could be achieved.

  2. Simulation of Thermal-hydraulic Process in Reactor of HTR-PM

    International Nuclear Information System (INIS)

    Zhou Kefeng; Zhou Yangping; Sui Zhe; Ma Yuanle

    2014-01-01

    This paper provides the physical process in the reactor of High Temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM) and introduces the standard operation conditions. The FORTRAN code developed for the thermal hydraulic module of Full-Scale Simulator (FSS) of HTR-PM is used to simulate two typical operation transients including cold startup process and cold shutdown process. And the results were compared to the safety analysis code, namely TINTE. The good agreement indicates that the code is applicable for simulating the thermal-hydraulic process in reactor of HTR-PM. And for long time transient process, the code shows good stability and convergence. (author)

  3. Numerical modeling of pyrolysis of sawdust in a packed bed

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  4. A discrete element method study on the evolution of thermomechanics of a pebble bed experiencing pebble failure

    Energy Technology Data Exchange (ETDEWEB)

    Van Lew, Jon T., E-mail: jtvanlew@fusion.ucla.edu; Ying, Alice; Abdou, Mohamed

    2014-10-15

    The discrete element method (DEM) is used to study the thermal effects of pebble failure in an ensemble of lithium ceramic spheres. Some pebbles crushing in a large system is unavoidable and this study provides correlations between the extent of pebble failure and the reduction in effective thermal conductivity of the bed. In the model, we homogeneously induced failure and applied nuclear heating until dynamic and thermal steady-state. Conduction between pebbles and from pebbles to the boundary is the only mode of heat transfer presently modeled. The effective thermal conductivity was found to decrease rapidly as a function of the percent of failed pebbles in the bed. It was found that the dominant contributor to the reduction was the drop in inter-particle forces as pebbles fail; implying the extent of failure induced may not occur in real pebble beds. The results are meant to assist designers in the fusion energy community who are planning to use packed beds of ceramic pebbles. The evolution away from experimentally measured thermomechanical properties as pebbles fail is necessary for proper operation of fusion reactors.

  5. Heat Transfer in Pebble-Bed Nuclear Reactor Cores Cooled by Fluoride Salts

    Science.gov (United States)

    Huddar, Lakshana Ravindranath

    With electricity demand predicted to rise by more than 50% within the next 20 years and a burgeoning world population requiring reliable emissions-free base-load electricity, can we design advanced nuclear reactors to help meet this challenge? At the University of California, Berkeley (UCB) Fluoride-salt-cooled High Temperature Reactors (FHR) are currently being investigated. FHRs are designed with better safety and economic characteristics than conventional light water reactors (LWR) currently in operation. These reactors operate at high temperature and low pressure making them more efficient and safer than LWRs. The pebble-bed FHR (PB-FHR) variant includes an annular nuclear reactor core that is filled with randomly packed pebble fuel. It is crucial to characterize the heat transfer within this unique geometry as this informs the safety limits of the reactor. The work presented in this dissertation focused on furthering the understanding of heat transfer in pebble-bed nuclear reactor cores using fluoride salts as a coolant. This was done through experimental, analytical and computational techniques. A complex nuclear system with a coolant that has never previously been in commercial use requires experimental data that can directly inform aspects of its design. It is important to isolate heat transfer phenomena in order to understand the underlying physics in the context of the PB-FHR, as well as to make decisions about further experimental work that needs to be done in support of developing the PB-FHR. Certain organic oils can simulate the heat transfer behaviour of the fluoride salt if relevant non-dimensional parameters are matched. The advantage of this method is that experiments can be done at a much lower temperature and at a smaller geometric scale compared to FHRs, thereby lowering costs. In this dissertation, experiments were designed and performed to collect data demonstrating similitude. The limitations of these experiments were also elucidated by

  6. Gas flow calculation with a turbulence model in a packed bed; Ranryu model wo mochiita juten sonai no gas nagare no keisan

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, K [Kawasaki Steel Corp., Tokyo (Japan); Lockwood, F

    1996-06-01

    For the rationalization of blast furnace operation, the gas flow in a packed bed is calculated using a turbulence model. For accurately determining the mixing of gasses, dispersion of particulates in a turbulence, turbulence diffusion, response rate, etc., in a packed bed, turbulence characteristics need be elucidated. For the calculation of combustion behavior of powdered coal blown into the blast furnace tuyere, in particular, the evaluation of gas turbulence behavior in the blow pipe and packed bed is indispensable. The dissipation rate of {kappa} has been defined from the mixing length Lm with the hydraulic diameter of the packed bed as its function and the turbulence energy ({kappa}), and now a {kappa}-Lm model is proposed, capable of evaluating the turbulence behavior in the packed bed. The parameters in the model may be determined using the actually measured values about diffusion behavior. The diffusion behavior of a tracer blown into the packed bed is simulated, and then agreement is found between the calculated values and measured values. Oxygen distribution under simplified raceway conditions is calculated. Once in the raceway, the radial concentration gradient of oxygen is much gentler suddenly, indicating the excellent mixture characteristics of the packed layer. 21 refs., 9 figs.

  7. Optimized Core Design and Fuel Management of a Pebble-Bed Type Nuclear Reactor

    International Nuclear Information System (INIS)

    Boer, Brian

    2007-01-01

    The Very High Temperature Reactor (VHTR) has been selected by the international Generation IV research initiative as one of the six most promising nuclear reactor concepts that are expected to enter service in the second half of the 21st century. The VHTR is characterized by a high plant efficiency and a high fuel discharge burnup level. More specifically, the (pebble-bed type) High Temperature Reactor (HTR) is known for its inherently safe characteristics, coming from a negative temperature reactivity feedback, a low power density and a large thermal inertia of the core. The core of a pebble-bed reactor consists of graphite spheres (pebbles) that form a randomly packed porous bed, which is cooled by high pressure helium. The pebbles contain thousands of fuel particles, which are coated with several pyrocarbon and silicon carbon layers that are designed to contain the fission products that are formed during operation of the reactor. The inherent safety concept has been demonstrated in small pebble-bed reactors in practice, but an increase in the reactor size and power is required for cost-effective power production. An increase of the power density in order to increase the helium coolant outlet temperature is attractive with regard to the efficiency and possible process heat applications. However, this increase leads in general to higher fuel temperatures, which could lead to a consequent increase of the fuel coating failure probability. This thesis deals with the pebble-bed type VHTR that aims at an increased coolant outlet temperature of 1000 degrees C and beyond. For the simulation of the neutronic and thermal-hydraulic behavior of the reactor the DALTON-THERMIX coupled code system has been developed and has been validated against experiments performed in the AVR and HTR-10 reactors. An analysis of the 400 MWth Pebble Bed Modular Reactor (PBMR) design shows that the inherent safety concept that has been demonstrated in practice in the smaller AVR and HTR-10

  8. Critical Issues for Particle-Bed Reactor Fuels

    Science.gov (United States)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  9. Immobilisation of laccase on Eupergit supports and its application for the removal of endocrine disrupting chemicals in a packed-bed reactor.

    Science.gov (United States)

    Lloret, L; Hollmann, F; Eibes, G; Feijoo, G; Moreira, M T; Lema, J M

    2012-06-01

    Laccase from Myceliophthora thermophila was covalently immobilised on Eupergit C and Eupergit C 250L yielding specific activities of up to 17 and 80 U/g, respectively. Due to its superior activity, Eupergit C 250L was chosen for further research. The somewhat lower catalytic efficiency (based on the ratio between the turnover number and the Michaelis constant, k(cat)/K(M)) of the immobilised enzyme in comparison with that of the free enzyme was balanced by its increased stability and broader operational window related to temperature and pH. The feasibility of the immobilised laccase was tested by using a packed bed reactor (PBR) operating in consecutive cycles for the removal of Acid Green 27 dye as model substrate. High degrees of elimination were achieved (88, 79, 69 and 57% in 4 consecutive cycles), while the levels of adsorption on the support varied from 18 to 6%, proving that dye removal took place mainly due to the action of the enzyme. Finally, a continuous PBR with the solid biocatalyst was applied for the treatment of a solution containing the following endocrine disrupting chemicals: estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2). At steady-state operation, E1 was degraded by 65% and E2 and EE2 were removed up to 80% and only limited adsorption of these compounds on the support, between 12 and 22%, was detected. In addition, a 79% decrease in estrogenic activity was detected in the effluent of the enzymatic reactor while only 14% was attained by inactivated laccase.

  10. Thermal conductivity of fusion solid breeder materials

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tam, S.W.

    1986-06-01

    Several simple and useful formulae for estimating the thermal conductivity of lithium-containing ceramic tritium breeder materials for fusion reactor blankets are given. These formulae account for the effects of irradiation, as well as solid breeder configuration, i.e., monolith or a packed bed. In the latter case, a coated-sphere concept is found more attractive in incorporating beryllia (a neutron multiplier) into the blanket than a random mixture of solid breeder and beryllia spheres

  11. Real time thermal hydraulic model for high temperature gas-cooled reactor core

    International Nuclear Information System (INIS)

    Sui Zhe; Sun Jun; Ma Yuanle; Zhang Ruipeng

    2013-01-01

    A real-time thermal hydraulic model of the reactor core was described and integrated into the simulation system for the high temperature gas-cooled pebble bed reactor nuclear power plant, which was developed in the vPower platform, a new simulation environment for nuclear and fossil power plants. In the thermal hydraulic model, the helium flow paths were established by the flow network tools in order to obtain the flow rates and pressure distributions. Meanwhile, the heat structures, representing all the solid heat transfer elements in the pebble bed, graphite reflectors and carbon bricks, were connected by the heat transfer network in order to solve the temperature distributions in the reactor core. The flow network and heat transfer network were coupled and calculated in real time. Two steady states (100% and 50% full power) and two transients (inlet temperature step and flow step) were tested that the quantitative comparisons of the steady results with design data and qualitative analysis of the transients showed the good applicability of the present thermal hydraulic model. (authors)

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  13. MIT pebble bed reactor project

    Energy Technology Data Exchange (ETDEWEB)

    Kadak, Andrew C. [Massachusetts Institute of Technology, Cambridge (United States)

    2007-03-15

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis.

  14. MIT pebble bed reactor project

    International Nuclear Information System (INIS)

    Kadak, Andrew C.

    2007-01-01

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis

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

    International Nuclear Information System (INIS)

    Pavlidis, D.; Lathouwers, D.

    2011-01-01

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

  16. 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.

  17. Thermal conversion of waste polyolefins to the mixture of hydrocarbons in the reactor with molten metal bed

    Energy Technology Data Exchange (ETDEWEB)

    Stelmachowski, M. [Department of Environmental Engineering, Faculty of Process and Environmental Engineering, Technical University of Lodz, 90-924 Lodz, Wolczanska 213 (Poland)

    2010-10-15

    Energy crisis and environmental degradation by polymer wastes have been imperative to find and propose technologies for recovery of raw materials and energy from non-conventional sources like organic wastes, plastic wastes, scrap tires, etc. A variety of methods and processes connected with global or national policies have been proposed worldwide. A new type of a tubular reactor with the molten metal bed is proposed for conversion of waste plastics to fuel-like mixture of hydrocarbons. The results of the thermal degradation of polyolefins in the laboratory scale set-up based on this reactor are presented in the paper. The melting and cracking processes were carried out in a single apparatus at the temperature 390-420 C. The problems with: disintegration of wastes, heat transfer from the wall to the particles of polymers, cooking at the walls of reactor, and mixing of the molten volume of wastes were significantly reduced. The final product consisted of gaseous stream (8-16 wt% of the input) and liquid (84-92 wt%) stream. No solid products were produced. The light, ''gasoline'' fraction of the liquid hydrocarbons mixture (C{sub 4}-C{sub 10}) made over 50% of the liquid product. It may by used for fuel production or electricity generation. (author)

  18. Thermal conversion of waste polyolefins to the mixture of hydrocarbons in the reactor with molten metal bed

    International Nuclear Information System (INIS)

    Stelmachowski, M.

    2010-01-01

    Energy crisis and environmental degradation by polymer wastes have been imperative to find and propose technologies for recovery of raw materials and energy from non-conventional sources like organic wastes, plastic wastes, scrap tires, etc. A variety of methods and processes connected with global or national policies have been proposed worldwide. A new type of a tubular reactor with the molten metal bed is proposed for conversion of waste plastics to fuel like mixture of hydrocarbons. The results of the thermal degradation of polyolefins in the laboratory scale set-up based on this reactor are presented in the paper. The melting and cracking processes were carried out in a single apparatus at the temperature 390-420 deg. C. The problems with: disintegration of wastes, heat transfer from the wall to the particles of polymers, cooking at the walls of reactor, and mixing of the molten volume of wastes were significantly reduced. The final product consisted of gaseous stream (8-16 wt% of the input) and liquid (84-92 wt%) stream. No solid products were produced. The light, 'gasoline' fraction of the liquid hydrocarbons mixture (C 4 -C 10 ) made over 50% of the liquid product. It may by used for fuel production or electricity generation.

  19. Numerical models for the analysis of thermal behavior and coolability of a particulate debris bed in reactor lower head

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kwang Il; Kim, Sang Baik; Kim, Byung Seok [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-04-01

    This report provides three distinctive, but closely related numerical models developed for the analysis of thermal behavior and coolability of a particulate debris bed that is may be formed inside the reactor lower head during severe accident late phases. The first numerical module presented in the report, MELTPRO-DRY, is used to analyze numerically heat-up and melting process of the dry particle bed, downward- and sideward-relocation of the liquid melt under gravity force and capillary force acting among porous particles, and solidification of the liquid melt relocated into colder region. The second module, MELTPROG-WET, is used to simulate numerically the cooling process of the particulate debris bed under the existence of water, which is subjected to two types of numerical models. The first type of WET module utilizes distinctive models that parametrically simulate the water cooling process, that is, quenching region, dryout region, and transition region. The choice of each parametric model depends on temperature gradient between the cooling water and the debris particles. The second type of WET module utilizes two-phase flow model that mechanically simulates the cooling process of the debris bed. For a consistent simulation from the water cooling to the dryout debris bed, on the other hand, the aforementioned two modules, MELTPROG-DRY and MELTPROG-WET, were integrated into a single computer program DBCOOL. Each of computational models was verified through limited applications to a heat-generating particulate bed contained in the rectangular cavity. 22 refs., 5 figs., 2 tabs. (Author)

  20. Kinetic model for an up-flow anaerobic packed bed bioreactor: Dairy ...

    African Journals Online (AJOL)

    Kinetic studies of anaerobic digestion process of cheese whey were conducted in a pilot-scale up-flow anaerobic packed bed bioreactor (UAPB). An influent COD concentration of 59419 mg/l was utilized at steady state condition. Logistic and Monod kinetic models were employed to describe microbial activities of cheese ...

  1. A parametric study pf powder holdups in a packed bed under ...

    African Journals Online (AJOL)

    More specifically, a parametric study is performed to determine the effects of the gas blast velocity, particle size adn powder loading on the powder holdups. Results are presented in terms of fines accumulation area. This work shows the dependency of the powder holdups on the packed bed flow parameters. Keywords: ...

  2. Experimental and computational investigation of flow of pebbles in a pebble bed nuclear reactor

    Science.gov (United States)

    Khane, Vaibhav B.

    The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding about slow and dense granular flow of pebbles is required from both a reactor safety and performance evaluation point of view. In this dissertation, a new integrated experimental and computational study of granular flow in a PBR has been performed. Continuous pebble re-circulation experimental set-up, mimicking flow of pebbles in a PBR, is designed and developed. Experimental investigation of the flow of pebbles in a mimicked test reactor was carried out for the first time using non-invasive radioactive particle tracking (RPT) and residence time distribution (RTD) techniques to measure the pebble trajectory, velocity, overall/zonal residence times, flow patterns etc. The tracer trajectory length and overall/zonal residence time is found to increase with change in pebble's initial seeding position from the center towards the wall of the test reactor. Overall and zonal average velocities of pebbles are found to decrease from the center towards the wall. Discrete element method (DEM) based simulations of test reactor geometry were also carried out using commercial code EDEM(TM) and simulation results were validated using the obtained benchmark experimental data. In addition, EDEM(TM) based parametric sensitivity study of interaction properties was carried out which suggests that static friction characteristics play an important role from a packed/pebble beds structural characterization point of view. To make the RPT technique viable for practical applications and to enhance its accuracy, a novel and dynamic technique for RPT calibration was designed and developed. Preliminary feasibility results suggest that it can be implemented as a non

  3. Plutonium burning in a pebble-bed type high temperature nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Bende, E.E

    2000-01-24

    parameters like the temperature coefficients of reactivity, the delayed neutron fractions and the mean neutron generation time as well as their evolutions during burnup are presented. The calculations for this parameter study still refer to an infinite pebble bed or, more precisely, to a 'pebble-cell' with isotropically reflecting boundaries. On the basis of the results of the cell calculations, two pebble configurations were chosen as viable candidates for fuel in a real reactor. These configurations embrace pebbles with either 1 g or 2 g Pu/pebble contained by coated particles with fuel kernel diameters of 220 {mu}m. Chapter 5 presents a conceptual design of a pebble-bed HTR that is operated with pebbles having the mentioned Pu-loadings. This design, which will be designated as the HTR-Pu, is a modified version of the Dutch ACACIA design, which is a small pebble-bed reactor, based on the Peu-a-Peu fuelling principle, with a thermal power of 40 MWth. The proposed reactor design is only a first try and has not been subject to any optimisation procedures. The calculations are performed by the PANTHERMIX-code system which establishes a coupling between the diffusion code PANTHER and the thermal-hydraulics code THERMIX/DIREKT. Section 5.4 reports the calculational results during normal operation. This embraces burnup calculations that simulate the continuous fuelling of pebbles on top of the initial pebble bed until the maximum core height is reached. Section 5.5 focuses on the excess reactivities, the control rod requirements and an envisaged start-up procedure of the HTR-Pu, for both Pu-loadings. Finally, section 5.6 shows the calculational results of the HTR-Pu under off-normal conditions. Several loss-of-cooling scenarios were simulated in order to examine whether the HTR's passive safety features are preserved in case the reactor is loaded with the mentioned Pu-fuels. Appendix A presents an analytic expression for the average Dancoff factor of a fuel kernel

  4. Continuous aryl alcohol oxidase production under growth-limited conditions using a trickle bed reactor.

    Science.gov (United States)

    Pardo-Planas, Oscar; Atiyeh, Hasan K; Prade, Rolf A; Müller, Michael; Wilkins, Mark R

    2018-05-01

    An A. nidulans strain with a pyridoxine marker was used for continuous production of aryl alcohol oxidase (AAO) in a trickle bed reactor (TBR). Modified medium with reduced zinc, no copper, and 5 g/L ascorbic acid that reduced melanin production and increased AAO productivity under growth limited conditions was used. Two air flow rates, 0.11 L/min (0.1 vvm) and 1.1 L/min (1.0 vvm) were tested. More melanin formation and reduced protein productivity were observed with air flow rate of 1.1 L/min. Three random packings were used as support for the fungus inside the TBR column, two of which were hydrophobic and one which was hydrophilic, and three different dilution rates were tested. The use of GEA BCN 030 hydrophobic packing resulted in greater AAO yield and productivity than the other packings. Increasing dilution rates favored melanin formation and citric, lactic and succinic acid accumulation, which decreased AAO yield and productivity. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters

    Science.gov (United States)

    Hinkle, S.R.; Böhlke, J.K.; Fisher, L.H.

    2008-01-01

    Septic tank systems are an important source of NO3- to many aquifers, yet characterization of N mass balance and isotope systematics following septic tank effluent discharge into unsaturated sediments has received limited attention. In this study, samples of septic tank effluent before and after transport through single-pass packed-bed filters (sand filters) were evaluated to elucidate mass balance and isotope effects associated with septic tank effluent discharge to unsaturated sediments. Chemical and isotopic data from five newly installed pairs and ten established pairs of septic tanks and packed-bed filters serving single homes in Oregon indicate that aqueous solute concentrations are affected by variations in recharge (precipitation, evapotranspiration), NH4+ sorption (primarily in immature systems), nitrification, and gaseous N loss via NH3 volatilization and(or) N2 or N2O release during nitrification/denitrification. Substantial NH4+ sorption capacity was also observed in laboratory columns with synthetic effluent. Septic tank effluent ??15N-NH4+ values were almost constant and averaged + 4.9??? ?? 0.4??? (1 ??). In contrast, ??15N values of NO3- leaving mature packed-bed filters were variable (+ 0.8 to + 14.4???) and averaged + 7.2??? ?? 2.6???. Net N loss in the two networks of packed-bed filters was indicated by average 10-30% decreases in Cl--normalized N concentrations and 2-3??? increases in ??15N, consistent with fractionation accompanying gaseous N losses and corroborating established links between septic tank effluent and NO3- in a local, shallow aquifer. Values of ??18O-NO3- leaving mature packed-bed filters ranged from - 10.2 to - 2.3??? (mean - 6.4??? ?? 1.8???), and were intermediate between a 2/3 H2O-O + 1/3 O2-O conceptualization and a 100% H2O-O conceptualization of ??18O-NO3- generation during nitrification.

  6. Endoglucanase production with the newly isolated Myceliophtora sp. i-1d3b in a packed bed solid state fermentor

    Directory of Open Access Journals (Sweden)

    A. I. Zanelato

    2012-12-01

    Full Text Available This work is aimed to produce endoglucanase through solid state fermentation in a packed bed bioreactor with the use of the fungus Myceliophtora sp. I-1D3busing a mixture of wheat bran (WB and sugar cane bagasse (SCB as culture medium. Preliminary tests were performed in polypropylene plastic bags, controlling the variables temperature (40, 45, and 50ºC, initial moisture content (75, 80, and 85%, w.b., and weight proportion SCB/WB (1:1, 7:3, and 9:1. The highest enzyme activities in plastic bags were obtained using the substrate proportion of 7:3, 50ºC temperature, and 80% initial moisture content (878 U/grams of dry solid. High activities of filter-paper cellulase and xylanase were also obtained in plastic bags and some results are reported. For the packed bed experiments, the temperature (45 and 50ºC and the air flow rate (80, 100 and 120L/h were the controlled variables. Activity of endoglucanase was similar to plastic bag tests. A longitudinal gradient of moisture content, was observed increasing from the bottom to the top of the reactor, even though the longitudinal enzyme activity profile was flat for almost the whole bed. Air flow rate did not affect enzyme activity, while experiments carried out at 50ºC showed higher enzyme activities. The maximum temperature peak observed was at about 6ºC above the process temperature.

  7. Solid-State Anaerobic Digestion of Dairy Manure from a Sawdust-Bedded Pack Barn: Moisture Responses

    Directory of Open Access Journals (Sweden)

    Eunjong Kim

    2018-02-01

    Full Text Available Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs of 70, 76, and 83% and digested at 37 °C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL (gVS−1. These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to three-month period before the manure was removed from the barn. However, in terms of efficient management of farm odors and providing a renewable energy source for heating, SS-AD of bedded pack manure offers a potential alternative to the conventional composting systems currently in use.

  8. Mathematical modelling of fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Werther, J [BASF A.G., Ludwigshafen am Rhein (Germany, F.R.)

    1978-11-01

    Among the many fluidized bed models to be found in the literature, the two-phase model originally proposed by May has proved most suitable for accomodation of recent advances in flow mechanics: this model resolves the gas/solids fluidized bed into a bubble phase and a suspension phase surrounding the bubbles. Its limitation to slow reactions is a disadvantage. On the basis of the analogy between fluidized beds and gas/liquid systems, a general two-phase model that is valid for fast reactions has therefore been developed and its validity is confirmed by comparison with the experimental results obtained by others. The model describes mass transfer across the phase interface with the aid of the film theory known from gas/liquid reactor technology, and the reaction occurring in the suspension phase as a pseudo-homogeneous reaction. Since the dependence of the performance of fluidized bed reactors upon geometry is accounted for, the model can also be used for scale-up calculations. Its use is illustrated with the aid of design diagrams.

  9. Oxidation of tritium in packed bed of noble metal catalyst for detritiation from system gases

    International Nuclear Information System (INIS)

    Nishikawa, Masabumi; Takeishi, Toshiharu; Munakata, Kenzo; Kotoh, Kenji; Enoeda, Mikio

    1985-01-01

    Catalytic oxidation rates of tritium in the bed of the noble metal catalysts are obtained and compared with the oxidation rates observed for the packed bed of spongy copper oxide or hopcalites. Use of Pt- or Pd-aluminia catalysts is recommended in this study because they give effective oxidation rates of tritium in the ambient temperature range. The adsorption performance of tritiated water in the catalyst bed is also discussed. (orig.)

  10. PENGARUH POROSITAS PACKING STEEL WOOL TERHADAP PRESSURE DROP DIDALAM PACKED BED COLUMN PADA DISTILASI CAMPURAN ETANOL-AMIL-ALKOHOL-AIR

    Directory of Open Access Journals (Sweden)

    Trisna Kumala Dhaniswara

    2016-08-01

    Full Text Available Inventories of petroleum fuels are increasingly depleted and will someday run out. These shortcomings can be overcome by using alternative fuels, such as ethanol. Based on this, it is necessary to research and development of ethanol as a fuel. One way is with a separation in a packed distillation column. This study aims to assess the mass transfer phenomena that occur in the process of distilling a mixture of ethanol-water-amyl alcohol packed in column. In addition, this study aims to optimize temperature and reflux to obtain the highest levels of ethanol. This research method uses packed bed distillation system with the batch process. Feed used is synthetic ethanol, water, and solvent. Solvent used were amyl alcohol. Doing distillation with heating temperature is maintained. Distillation is done in the packing of stainless steel wool. Research carried out in a batch process with a variable temperature of  79°C; 84°C; 91°C; and porosity packing 20%; 30%; 40%; 50%; 60%; 70%; 80%.

  11. Hexavalent chromium reduction in a sulfur reducing packed-bed bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Sahinkaya, Erkan, E-mail: erkansahinkaya@yahoo.com [Department of Bioengineering, Istanbul Medeniyet University, Goeztepe, Istanbul (Turkey); Kilic, Adem [Department of Environmental Engineering, Harran University, Osmanbey Campus, 63000 Sanliurfa (Turkey); Altun, Muslum [Department of Chemistry, Hacettepe University, Beytepe, Ankara (Turkey); Komnitsas, Kostas [Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania (Greece); Lens, Piet N.L. [Unesco-IHE Institute for Water Education, Westvest 7, Delft 2611 AX (Netherlands)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Elemental sulfur can be used as electron acceptor for sulfide production. Black-Right-Pointing-Pointer Biogenically produced sulfide reduces Cr(VI) to the much less toxic and immobile form of Cr(III). Black-Right-Pointing-Pointer Sulfur packed bioreactor is efficient for Cr(VI) containing wastewater treatment. Black-Right-Pointing-Pointer Reduced form of chromium precipitates in the bioreactor. - Abstract: The most commonly used approach for the detoxification of hazardous industrial effluents and wastewaters containing Cr(VI) is its reduction to the much less toxic and immobile form of Cr(III). This study investigates the cleanup of Cr(VI) containing wastewaters using elemental sulfur as electron acceptor, for the production of hydrogen sulfide that induces Cr(VI) reduction. An elemental sulfur reducing packed-bed bioreactor was operated at 28-30 Degree-Sign C for more than 250 days under varying influent Cr(VI) concentrations (5.0-50.0 mg/L) and hydraulic retention times (HRTs, 0.36-1.0 day). Ethanol or acetate (1000 mg/L COD) was used as carbon source and electron donor. The degree of COD oxidation varied between 30% and 85%, depending on the operating conditions and the type of organic carbon source. The oxidation of organic matter was coupled with the production of hydrogen sulfide, which reached a maximum concentration of 750 mg/L. The biologically produced hydrogen sulfide reduced Cr(VI) chemically to Cr(III) that precipitated in the reactor. Reduction of Cr(VI) and removal efficiency of total chromium always exceeded 97% and 85%, respectively, implying that the reduced chromium was retained in the bioreactor. This study showed that sulfur can be used as an electron acceptor to produce hydrogen sulfide that induces efficient reduction and immobilization of Cr(VI), thus enabling decontamination of Cr(VI) polluted wastewaters.

  12. Determination of pressure distribution in an aerated bed in a controlled pilot-scale compost reactor

    Energy Technology Data Exchange (ETDEWEB)

    Solowiej, P. [Warmia and Mazury Univ., Olsztyn (Poland)

    2010-07-01

    This study investigated the effectiveness of dealing with biological waste by composting. In particular, it examined the feasibility of recovering excess thermal energy produced in the process of composting biological waste in terms of mass and energy transport parameters required in the aerated compost bed. An experiment was performed in which a 100 dm{sup 3} adiabatic, leak-tight reactor equipped with a controlled aeration system was constructed to study the temperature and pressure distribution in the bed. Sensors were used to determine the amount and humidity of emitted gases under variable external physical conditions. The perforated bottom of the reactor allowed for bed aeration. As such, the humidity and heat were transported upwards, forced by the air pumped in and by natural convection. In terms of pressure distribution inside the composted and aerated bed, the study results showed that there were considerable differences in pressure for the selected places of the bed of the composted biological material. An increase in upwards pressure was observed in the heap throughout the experiment. Pressure differences in the same plane of the bed were also noted. The study results should facilitate the development of a model of mass and energy transport in a bed of composted material.

  13. Pebble bed modular reactor - The first Generation IV reactor to be constructed

    International Nuclear Information System (INIS)

    Ion, S.; Nicholls, D.; Matzie, R.; Matzner, D.

    2004-01-01

    Substantial interest has been generated in advanced reactors over the past few years. This interest is motivated by the view that new nuclear power reactors will be needed to provide low carbon generation of electricity and possibly hydrogen to support the future growth in demand for both of these commodities. Some governments feel that substantially different designs will be needed to satisfy the desires for public perception, improved safety, proliferation resistance, reduced waste and competitive economics. This has motivated the creation of the Generation IV Nuclear Energy Systems programme in which ten countries have agreed on a framework for international cooperation in research for advanced reactors. Six designs have been selected for continued evaluation, with the objective of deployment by 2030. One of these designs is the very high temperature reactor (VHTR), which is a thermal neutron spectrum system with a helium-cooled core utilising carbon-based fuel. The pebble bed modular reactor (PBMR), being developed in South Africa through a worldwide international collaborative effort led by Eskom, the national utility, will represent a key milestone on the way to achievement of the VHTR design objectives, but in the much nearer term. This paper outlines the design objectives, safety approach and design details of the PBMR, which is already at a very advanced stage of development. (author)

  14. Advanced Catalysis Technologies: Lanthanum Cerium Manganese Hexaaluminate Combustion Catalysts for Flat Plate Reactor for Compact Steam Reformers

    Science.gov (United States)

    2008-12-01

    packed-bed steam reformer reactor using an open-flame or radiant burner as the heat source, the rate of heat transfer is limited by wall film and bed...resistances. Heat transfer can be effectively improved by replacing the burner /packed-bed system with parallel channels containing metal foam...combustion reactor was tested using the hexaaluminate catalyst in pellets and supported on FeCrAlloy metal foam. Both tests burned propane and JP-8

  15. Core homogenization method for pebble bed reactors

    International Nuclear Information System (INIS)

    Kulik, V.; Sanchez, R.

    2005-01-01

    This work presents a core homogenization scheme for treating a stochastic pebble bed loading in pebble bed reactors. The reactor core is decomposed into macro-domains that contain several pebble types characterized by different degrees of burnup. A stochastic description is introduced to account for pebble-to-pebble and pebble-to-helium interactions within a macro-domain as well as for interactions between macro-domains. Performance of the proposed method is tested for the PROTEUS and ASTRA critical reactor facilities. Numerical simulations accomplished with the APOLLO2 transport lattice code show good agreement with the experimental data for the PROTEUS reactor facility and with the TRIPOLI4 Monte Carlo simulations for the ASTRA reactor configuration. The difference between the proposed method and the traditional volume-averaged homogenization technique is negligible while only one type of fuel pebbles present in the system, but it grows rapidly with the level of pebble heterogeneity. (authors)

  16. Pebble Bed Reactor Dust Production Model

    Energy Technology Data Exchange (ETDEWEB)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  17. Pebble Bed Reactor Dust Production Model

    International Nuclear Information System (INIS)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-01-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production

  18. Acetone-butanol-ethanol (ABE) fermentation in an immobilized cell trickle bed reactor.

    Science.gov (United States)

    Park, C H; Okos, M R; Wankat, P C

    1989-06-05

    Acetone-butanol-ethanol (ABE) fermentation was successfully carried out in an immobilized cell trickle bed reactor. The reactor was composed of two serial columns packed with Clostridium acetobutylicum ATCC 824 entrapped on the surface of natural sponge segments at a cell loading in the range of 2.03-5.56 g dry cells/g sponge. The average cell loading was 3.58 g dry cells/g sponge. Batch experiments indicated that a critical pH above 4.2 is necessary for the initiation of cell growth. One of the media used during continuous experiments consisted of a salt mixture alone and the other a nutrient medium containing a salt mixture with yeast extract and peptone. Effluent pH was controlled by supplying various fractions of the two different types of media. A nutrient medium fraction above 0.6 was crucial for successful fermentation in a trickle bed reactor. The nutrient medium fraction is the ratio of the volume of the nutrient medium to the total volume of nutrient plus salt medium. Supplying nutrient medium to both columns continuously was an effective way to meet both pH and nutrient requirement. A 257-mL reactor could ferment 45 g/L glucose from an initial concentration of 60 g/L glucose at a rate of 70 mL/h. Butanol, acetone, and ethanol concentrations were 8.82, 5.22, and 1.45 g/L, respectively, with a butanol and total solvent yield of 19.4 and 34.1 wt %. Solvent productivity in an immobilized cell trickle bed reactor was 4.2 g/L h, which was 10 times higher than that obtained in a batch fermentation using free cells and 2.76 times higher than that of an immobilized CSTR. If the nutrient medium fraction was below 0.6 and the pH was below 4.2, the system degenerated. Oxygen also contributed to the system degeneration. Upon degeneration, glucose consumption and solvent yield decreased to 30.9 g/L and 23.0 wt %, respectively. The yield of total liquid product (40.0 wt %) and butanol selectivity (60.0 wt %) remained almost constant. Once the cells were degenerated

  19. Friction factor for water flow through packed beds of spherical and non-spherical particles

    Directory of Open Access Journals (Sweden)

    Kaluđerović-Radoičić Tatjana

    2017-01-01

    Full Text Available The aim of this work was the experimental evaluation of different friction factor correlations for water flow through packed beds of spherical and non-spherical particles at ambient temperature. The experiments were performed by measuring the pressure drop across the bed. Packed beds made of monosized glass spherical particles of seven different diameters were used, as well as beds made of 16 fractions of quartz filtration sand obtained by sieving (polydisperse non-spherical particles. The range of bed voidages was 0.359–0.486, while the range of bed particle Reynolds numbers was from 0.3 to 286 for spherical particles and from 0.1 to 50 for non-spherical particles. The obtained results were compared using a number of available literature correlations. In order to improve the correlation results for spherical particles, a new simple equation was proposed in the form of Ergun’s equation, with modified coefficients. The new correlation had a mean absolute deviation between experimental and calculated values of pressure drop of 9.04%. For non-spherical quartz filtration sand particles the best fit was obtained using Ergun’s equation, with a mean absolute deviation of 10.36%. Surface-volume diameter (dSV necessary for correlating the data for filtration sand particles was calculated based on correlations for dV = f(dm and Ψ = f(dm. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. ON172022

  20. Condensation in Nanoporous Packed Beds.

    Science.gov (United States)

    Ally, Javed; Molla, Shahnawaz; Mostowfi, Farshid

    2016-05-10

    In materials with tiny, nanometer-scale pores, liquid condensation is shifted from the bulk saturation pressure observed at larger scales. This effect is called capillary condensation and can block pores, which has major consequences in hydrocarbon production, as well as in fuel cells, catalysis, and powder adhesion. In this study, high pressure nanofluidic condensation studies are performed using propane and carbon dioxide in a colloidal crystal packed bed. Direct visualization allows the extent of condensation to be observed, as well as inference of the pore geometry from Bragg diffraction. We show experimentally that capillary condensation depends on pore geometry and wettability because these factors determine the shape of the menisci that coalesce when pore filling occurs, contrary to the typical assumption that all pore structures can be modeled as cylindrical and perfectly wetting. We also observe capillary condensation at higher pressures than has been done previously, which is important because many applications involving this phenomenon occur well above atmospheric pressure, and there is little, if any, experimental validation of capillary condensation at such pressures, particularly with direct visualization.

  1. Optimization analysis of thermal management system for electric vehicle battery pack

    Science.gov (United States)

    Gong, Huiqi; Zheng, Minxin; Jin, Peng; Feng, Dong

    2018-04-01

    Electric vehicle battery pack can increase the temperature to affect the power battery system cycle life, charge-ability, power, energy, security and reliability. The Computational Fluid Dynamics simulation and experiment of the charging and discharging process of the battery pack were carried out for the thermal management system of the battery pack under the continuous charging of the battery. The simulation result and the experimental data were used to verify the rationality of the Computational Fluid Dynamics calculation model. In view of the large temperature difference of the battery module in high temperature environment, three optimization methods of the existing thermal management system of the battery pack were put forward: adjusting the installation position of the fan, optimizing the arrangement of the battery pack and reducing the fan opening temperature threshold. The feasibility of the optimization method is proved by simulation and experiment of the thermal management system of the optimized battery pack.

  2. A systems CFD model of a packed bed high temperature gas-cooled nuclear reactor

    International Nuclear Information System (INIS)

    Du Toit, C.G.; Rousseau, P.G.; Greyvenstein, G.P.; Landman, W.A.

    2006-01-01

    The theoretical basis and conceptual formulation of a comprehensive reactor model to simulate the thermal-fluid phenomena of the PBMR reactor core and core structures is given. Through a rigorous analysis the fundamental equations are recast in a form that is suitable for incorporation in a systems CFD code. The formulation of the equations results in a collection of one-dimensional elements (models) that can be used to construct a comprehensive multi-dimensional network model of the reactor. The elements account for the pressure drop through the reactor; the convective heat transport by the gas; the convection heat transfer between the gas and the solids; the radiative, contact and convection heat transfer between the pebbles and the heat conduction in the pebbles. Results from the numerical model are compared with that of experiments conducted on the SANA facility covering a range of temperatures as well as two different fluids and different heating configurations. The good comparison obtained between the simulated and measured results show that the systems CFD approach sufficiently accounts for all of the important phenomena encountered in the quasi-steady natural convection driven flows that will prevail after critical events in a reactor. The fact that the computer simulation time for all of the simulations was less than three seconds on a standard notebook computer also indicates that the new model indeed achieves a fine balance between accuracy and simplicity. The new model can therefore be used with confidence and still allow quick integrated plant simulations. (authors)

  3. PRODUCTION OF MEDIUM-CHAIN ACYLGLYCEROLS BY LIPASE ESTERIFICATION IN PACKED BED REACTOR: PROCESS OPTIMIZATION BY RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    ZANARIAH MOHD DOM

    2014-06-01

    Full Text Available Medium-chain acylglycerols (or glycerides are formed of mono-, di- and triacylglycerol classes. In this study, an alternative method to produce MCA from esterifying palm oil fatty acid distillate (PFAD with the presence of oil palm mesocarp lipase (OPML which is a plant-sourced lipase and PFAD is also cheap by-product is developed in a packed bed reactor. The production of medium-chain acylglycerols (MCA by lipase-catalysed esterification of palm oil fatty acid distillate with glycerol are optimize in order to determine the factors that have significant effects on the reaction condition and high yield of MCA. Response surface methodology (RSM was applied to optimize the reaction conditions. The reaction conditions, namely, the reaction time (30-240 min, enzyme load (0.5-1.5 kg, silica gel load (0.2-1.0 kg, and solvent amount (200-600 vol/wt. Reaction time, enzyme loading and solvent amount strongly effect MCA synthesis (p0.05 influence on MCA yield. Best-fitting models were successfully established for MCA yield (R 2 =0.9133. The optimum MCA yield were 75% from the predicted value and 75.4% from the experimental data for 6 kg enzyme loading, a reaction time of 135min and a solvent amount of 350 vol/wt at 65ºC reaction temperature. Verification of experimental results under optimized reaction conditions were conducted, and the results agreed well with the predicted range. Esterification products (mono-, di- and triacylglycerol from the PBR were identified using Thin Layer Chromatography method. The chromatograms showed the successful fractionation of esterified products in this alternative method of process esterification.

  4. Biodegradation of 4-bromophenol by Arthrobacter chlorophenolicus A6 in batch shake flasks and in a continuously operated packed bed reactor.

    Science.gov (United States)

    Sahoo, Naresh Kumar; Pakshirajan, Kannan; Ghosh, Pranab Kumar

    2014-04-01

    The present study investigated growth and biodegradation of 4-bromophenol (4-BP) by Arthrobacter chlorophenolicus A6 in batch shake flasks as well as in a continuously operated packed bed reactor (PBR). Batch growth kinetics of A. chlorophenolicus A6 in presence of 4-BP followed substrate inhibition kinetics with the estimated biokinetic parameters value of μ max = 0.246 h(-1), K i = 111 mg L(-1), K s  = 30.77 mg L(-1) and K = 100 mg L(-1). In addition, variations in the observed and theoretical biomass yield coefficient and maintenance energy of the culture were investigated at different initial 4-BP concentration. Results indicates that the toxicity tolerance and the biomass yield of A. chlorophenolicus A6 towards 4-BP was found to be poor as the organism utilized the substrate mainly for its metabolic maintenance energy. Further, 4-BP biodegradation performance by the microorganism was evaluated in a continuously operated PBR by varying the influent concentration and hydraulic retention time in the ranges 400-1,200 mg L(-1) and 24-7.5 h, respectively. Complete removal of 4-BP was achieved in the PBR up to a loading rate of 2,276 mg L(-1) day(-1).

  5. Numerical study on hygroscopic material drying in packed bed

    Directory of Open Access Journals (Sweden)

    M. Stakić

    2011-06-01

    Full Text Available The paper addresses numerical simulation for the case of convective drying of hygroscopic material in a packed bed, analyzing agreement between the simulated and the corresponding experimental results. In the simulation model of unsteady simultaneous one-dimensional heat and mass transfer between gas phase and dried material, it is assumed that the gas-solid interface is at thermodynamic equilibrium, while the drying rate of the specific product is calculated by applying the concept of a "drying coefficient". Model validation was done on the basis of the experimental data obtained with potato cubes. The obtained drying kinetics, both experimental and numerical, show that higher gas (drying agent velocities (flow-rates, as well as lower equivalent grain diameters, induce faster drying. This effect is more pronounced for deeper beds, because of the larger amount of wet material to be dried using the same drying agent capacity.

  6. Gas reactor international cooperative program interim report. Pebble bed reactor fuel cycle evaluation

    International Nuclear Information System (INIS)

    1978-09-01

    Nuclear fuel cycles were evaluated for the Pebble Bed Gas Cooled Reactor under development in the Federal Republic of Germany. The basic fuel cycle specified for the HTR-K and PNP is well qualified and will meet the requirements of these reactors. Twenty alternate fuel cycles are described, including high-conversion cycles, net-breeding cycles, and proliferation-resistant cycles. High-conversion cycles, which have a high probability of being successfully developed, promise a significant improvement in resource utilization. Proliferation-resistant cycles, also with a high probability of successful development, compare very favorably with those for other types of reactors. Most of the advanced cycles could be adapted to first-generation pebble bed reactors with no significant modifications

  7. Atomic reactor thermal engineering

    International Nuclear Information System (INIS)

    Kim, Gwang Ryong

    1983-02-01

    This book starts the introduction of atomic reactor thermal engineering including atomic reaction, chemical reaction, nuclear reaction neutron energy and soon. It explains heat transfer, heat production in the atomic reactor, heat transfer of fuel element in atomic reactor, heat transfer and flow of cooler, thermal design of atomic reactor, design of thermodynamics of atomic reactor and various. This deals with the basic knowledge of thermal engineering for atomic reactor.

  8. Fluid dynamics of air in a packed bed: velocity profiles and the continuum model assumption

    Directory of Open Access Journals (Sweden)

    NEGRINI A. L.

    1999-01-01

    Full Text Available Air flow through packed beds was analyzed experimentally under conditions ranging from those that reinforce the effect of the wall on the void fraction to those that minimize it. The packing was spherical particles, with a tube-to-particle diameter ratio (D/dp between 3 and 60. Air flow rates were maintained between 1.3 and 4.44 m3/min, and gas velocity was measured with a Pitot tube positioned above the bed exit. Measurements were made at various radial and angular coordinate values, allowing the distribution of air flow across the bed to be described in detail. Comparison of the experimentally observed radial profiles with those derived from published equations revealed that at high D/dp ratios the measured and calculated velocity profiles behaved similarly. At low ratios, oscillations in the velocity profiles agreed with those in the voidage profiles, signifying that treating the porous medium as a continuum medium is questionable in these cases.

  9. Measurements of the purge helium pressure drop across pebble beds packed with lithium orthosilicate and glass pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Sena, Ali, E-mail: ali.abou-sena@kit.edu; Arbeiter, Frederik; Boccaccini, Lorenzo V.; Schlindwein, Georg

    2014-10-15

    Highlights: • The objective is to measure the purge helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. • The purge helium pressure drop significantly increases with decreasing the pebbles diameter from one run to another. • At the same superficial velocity, the pressure drop is directly proportional to the helium inlet pressure. • The Ergun's equation can successfully model the purge helium pressure drop for the HCPB-relevant pebble beds. • The measured values of the purge helium pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB breeder units. - Abstract: The lithium orthosilicate pebble beds of the Helium Cooled Pebble Bed (HCPB) blanket are purged by helium to transport the produced tritium to the tritium extraction system. The pressure drop of the purge helium has a direct impact on the required pumping power and is a limiting factor for the purge mass flow. Therefore, the objective of this study is to measure the helium pressure drop across various HCPB-relevant pebble beds packed with lithium orthosilicate and glass pebbles. The pebble bed was formed by packing the pebbles into a stainless steel cylinder (ID = 30 mm and L = 120 mm); then it was integrated into a gas loop that has four variable-speed side-channel compressors to regulate the helium mass flow. The static pressure was measured at two locations (100 mm apart) along the pebble bed and at inlet and outlet of the pebble bed. The results demonstrated that: (i) the pressure drop significantly increases with decreasing the pebbles diameter, (ii) for the same superficial velocity, the pressure drop is directly proportional to the inlet pressure, and (iii) predictions of Ergun's equation agree well with the experimental results. The measured pressure drop for the lithium orthosilicate pebble bed will support the design of the purge gas system for the HCPB.

  10. Experiments on forced convection form a horizontal heated plate in a packed bed of glass spheres

    Energy Technology Data Exchange (ETDEWEB)

    Renken, K.J. (Univ. of Wisconsin, Milwaukee (USA)); Poulikakos, D. (Univ. of Illinois, Chicago (USA))

    1989-02-01

    This paper presents an experimental investigation of boundary-layer forced convective heat transfer from a flat isothermal plate in a packed bed of spheres. Extensive experimental results are reported for the thermal boundary-layer thickness, the temperature field, and the local wall heat flux (represented by the local Nusselt number). Theoretical findings of previous investigations using the Darcy flow model as well as a general model for themomentum equation accouting for flow inertia and macroscopic shear wtih and without variable porosity are used to evaluate the theoretical models. Several trends are revealed regarding the conditions of validity of these flow models. Overall the general flow model including variable porosity appears to perform better, even through the need for serious improvements in modeling becomes apparent.

  11. X-ray digital industrial radiography (DIR) for local liquid velocity (VLL) measurement in trickle bed reactors (TBRs): Validation of the technique

    Science.gov (United States)

    Mohd Salleh, Khairul Anuar; Rahman, Mohd Fitri Abdul; Lee, Hyoung Koo; Al Dahhan, Muthanna H.

    2014-06-01

    Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (VLL) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the VLL within TBRs.

  12. Magnetohydraulic flow through a packed bed of electrically conducting spheres

    International Nuclear Information System (INIS)

    Sanders, T.L.

    1985-01-01

    The flow of an electrically conducting fluid through a packed bed of electrically conducting spheres in the presence of a strong magnetic field constitutes a very complex flow situation due to the constant turning of the fluid in and out of magnetic field lines. The interaction of the orthogonal components of the velocity and magnetic field will induce electric fields that are orthogonal to both and the electric fields in turn can cause currents that interact with the magnetic field to generate forces against the direction of flow. The strengths of these generated forces depend primarily upon the closure paths taken by the induced currents which, in turn, depend upon the relative ratio of the electrical resistance of the solid spheres to that of the fluid. Both experimental and analytical analyses of the slow flow of a eutectic mixture of sodium and potassium (NaK) through packed cylinders containing stainless steel spheres in the presence of a strong transverse magnetic field were completed. A theory of magnetohydraulic flow is developed by analogy with the development of hydraulic radius theories of flow through porous media. An exact regional analysis is successfully applied to an infinite bed of electrically conducting spheres with a conducting or non-conducting constraining wall on one side. The equations derived are solved for many different combinations of flowrate, magnetic field strength, porosity, and electrical resistance ratio

  13. Separate effects tests to determine the thermal dispersion in structured pebble beds in the PBMR HPTU test facility

    Energy Technology Data Exchange (ETDEWEB)

    Toit, C.G. du, E-mail: jat.dutoit@nwu.ac.za; Rousseau, P.G.; Kgame, T.L.

    2014-05-01

    Thermal-fluid simulations are used extensively to predict the maximum fuel temperatures, flows, pressure drops and thermal capacitance of pebble bed gas cooled reactors in support of the reactor safety case. The PBMR company developed the HTTF test facility in cooperation with M-Tech Industrial (Pty) Ltd. and the North-West University in South Africa to conduct comprehensive separate effects tests as well as integrated effects tests to study the different thermal-fluid phenomena. This paper describes the separate effects tests that were conducted to determine the effect of the porous structure on the fluid effective thermal conductivity due to the thermal dispersion. It also presents the methodology applied in the data analysis to derive the resultant values of the effective thermal conductivity and its associated uncertainty.

  14. Influence of accuracy of thermal property data of a phase change material on the result of a numerical model of a packed bed latent heat storage with spheres

    Energy Technology Data Exchange (ETDEWEB)

    Arkar, C.; Medved, S. [University of Ljubljana, Faculty of Mechanical Engineering, Askerceva 6, 1000 Ljubljana (Slovenia)

    2005-11-01

    With the integration of latent-heat thermal energy storage (LHTES) in building services, solar energy and the coldness of ambient air can be efficiently used to reduce the energy used for heating and cooling and to improve the level of living comfort. For this purpose, a cylindrical LHTES containing spheres filled with paraffin was developed. For the proper modelling of the LHTES thermal response the thermal properties of the phase change material (PCM) must be accurately known. This article presents the influence of the accuracy of thermal property data of the PCM on the result of the prediction of the LHTES's thermal response. A packed bed numerical model was adapted to take into account the non-uniformity of the PCM's porosity and the fluid's velocity. Both are the consequence of a small tube-to-sphere diameter ratio, which is characteristic of the developed LHTES. The numerical model can also take into account the PCM's temperature-dependent thermal properties. The temperature distribution of the latent heat of the paraffin (RT20) used in the experiment in the form of apparent heat capacity was determined using a differential scanning calorimeter (DSC) at different heating and cooling rates. A comparison of the numerical and experimental results confirmed our hypothesis relating to the important role that the PCM's thermal properties play, especially during slow running processes, which are characteristic for our application.

  15. Hydrolysis of cellulose in a cellulase-bead fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Karube, I; Tanaka, S; Shirai, T; Suzuki, S

    1977-08-01

    Cellulase was immobilized in a collagen fibril matrix, and no leakage of cellulase from the collagen fibril matrix was observed. The immobilized cellulase was more stable than the native cellulase. The substrate cellulose was hydrolyzed quantitatively with immobilized cellulase. The final reaction product was identified as glucose. Immobilized cellulase was used in a fluidized bed reactor where the pressure drop of the fluidized bed reactor was low and constant. Cellulose was hydrolyzed to glucose by the cellulase-bead fluidized bed reactor. The minimum flow velocity (U/sub mf/) was 0.5 cm/sec and the optimum flow velocity of the cellulose hydrolysis was 1 cm/sec.

  16. Lagrangian Approach to Study Catalytic Fluidized Bed Reactors

    Science.gov (United States)

    Madi, Hossein; Hossein Madi Team; Marcelo Kaufman Rechulski Collaboration; Christian Ludwig Collaboration; Tilman Schildhauer Collaboration

    2013-03-01

    Lagrangian approach of fluidized bed reactors is a method, which simulates the movement of catalyst particles (caused by the fluidization) by changing the gas composition around them. Application of such an investigation is in the analysis of the state of catalysts and surface reactions under quasi-operando conditions. The hydrodynamics of catalyst particles within a fluidized bed reactor was studied to improve a Lagrangian approach. A fluidized bed methanation employed in the production of Synthetic Natural Gas from wood was chosen as the case study. The Lagrangian perspective was modified and improved to include different particle circulation patterns, which were investigated through this study. Experiments were designed to evaluate the concepts of the model. The results indicate that the setup is able to perform the designed experiments and a good agreement between the simulation and the experimental results were observed. It has been shown that fluidized bed reactors, as opposed to fixed beds, can be used to avoid the deactivation of the methanation catalyst due to carbon deposits. Carbon deposition on the catalysts tested with the Lagrangian approach was investigated by temperature programmed oxidation (TPO) analysis of ex-situ catalyst samples. This investigation was done to identify the effects of particles velocity and their circulation patterns on the amount and type of deposited carbon on the catalyst surface. Ecole Polytechnique Federale de Lausanne(EPFL), Paul Scherrer Institute (PSI)

  17. Rotating bed reactor for CLC: Bed characteristics dependencies on internal gas mixing

    International Nuclear Information System (INIS)

    Håkonsen, Silje Fosse; Grande, Carlos A.; Blom, Richard

    2014-01-01

    Highlights: • A mathematical model for the rotating CLC reactor has been developed. • The model reflects the gas distribution in the reactor during CLC operation. • Radial dispersion in the rotating bed is the main cause for internal gas mixing. • The model can be used to optimize the reactor design and particle characteristics. - Abstract: A newly designed continuous lab-scale rotating bed reactor for chemical looping combustion using CuO/Al 2 O 3 oxygen carrier spheres and methane as fuel gives around 90% CH 4 conversion and >90% CO 2 capture efficiency based on converted methane at 800 °C. However, from a series of experiments using a broad range of operating conditions potential CO 2 purities only in the range 20–65% were yielded, mostly due to nitrogen slip from the air side of the reactor into the effluent CO 2 stream. A mathematical model was developed intending to understand the air-mixing phenomena. The model clearly reflects the gas slippage tendencies observed when varying the process conditions such as rotation frequency, gas flow and the flow if inert gas in the two sectors dividing the air and fuel side of the reactor. Based on the results, it is believed that significant improvements can be made to reduce gas mixing in future modified and scaled-up reactor versions

  18. Analytical calculation of the fuel temperature reactivity coefficient for pebble bed and prismatic high temperature reactors for plutonium and uranium-thorium fuels

    International Nuclear Information System (INIS)

    Talamo, Alberto

    2007-01-01

    We analytically evaluated the fuel coefficient of temperature both for pebble bed and prismatic high temperature reactors when they utilize as fuel plutonium and minor actinides from light water reactors spent fuel or a mixture of 50% uranium, enriched 20% in 235 U, and 50% thorium. In both cores the calculation involves the evaluation of the resonances integrals of the high absorbers fuel nuclides 240 Pu, 238 U and 232 Th and it requires the esteem of the Dancoff-Ginsburg factor for a pebble bed or prismatic core. The Dancoff-Ginsburg factor represents the only discriminating parameter in the results for the two different reactors types; in fact, both the pebble bed and the prismatic reactors share the same the pseudo-cross-section describing an infinite medium made of graphite filled by TRISO particles. We considered only the resolved resonances with a statistical spin factor equal to one and we took into account 267, 72, 212 resonances in the range 1.057-5692, 6.674-14485, 21.78-3472 eV for 240 Pu, 238 U and 232 Th, respectively, for investigating the influence on the fuel temperature reactivity coefficient of the variation of the TRISO kernel radius and TRISO particles packing fraction from 100, 200 to 300 μm and from 10% to 50%, respectively. Finally, in the pebble bed core, we varied the radius of the pebble for setting a fuel temperature reactivity coefficient similar to the one of a prismatic core

  19. Investigation of effective thermal conductivity for pebble beds by one-way coupled CFD-DEM method for CFETR WCCB

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China); Chen, Youhua [University of Science and Technology of China, Hefei, Anhui 230027 (China); Huang, Kai [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2016-05-15

    Highlights: • A CFD-DEM coupled numerical model is built based on the prototypical blanket pebble bed. • The numerical model can be applied to simulate heat transfer of a pebble bed and estimate effective thermal conductivity. • The numerical model agrees well with the theoretical SZB model. • Effective thermal conductivity of pebble beds for WCCB is estimated by the current model. - Abstract: The mono-sized beryllium pebble bed and the multi-sized Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed are the main schemes for the Water-cooled ceramic breeder blanket (WCCB) of China Fusion Engineering Test Reactor (CFETR). And the effective thermal conductivity (k{sub eff}) of the pebble beds is important to characterize the thermal performance of WCCB. In this study, a one-way coupled CFD-DEM method was employed to simulate heat transfer and estimate k{sub eff}. The geometric topology of a prototypical blanket pebble bed was produced by the discrete element method (DEM). Based on the geometric topology, the temperature distribution and the k{sub eff} were obtained by the computational fluid dynamics (CFD) analysis. The current numerical model presented a good performance to calculate k{sub eff} of the beryllium pebble bed, and according to the modeling of the Li{sub 2}TiO{sub 3}/Be{sub 12}Ti mixed pebble bed, k{sub eff} was estimated with values ranged between 2.0 and 4.0 W/(m∙K).

  20. An energy amplifier fluidized bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Sefidvash, F.; Seifritz, W.

    2001-01-01

    The concept of a fluidized bed nuclear reactor driven by an energy amplifier system is described. The reactor has promising characteristics of inherent safety and passive cooling. The reactor can easily operate with any desired spectrum in order to be a plutonium burner or have it operate with thorium fuel cycle. (orig.) [de

  1. Operational methods of the fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Borges, V.; Sefidvash, F.

    1993-01-01

    The operational curve of reactivity as a function of porosity of the Fluidized Bed Nuclear Reactor is presented. The strategies for start-up, shut-down and maintaining the reactor critical during operation are described. The inherent safety of the reactor from neutronic point of view under steady state condition is demonstrated. (author)

  2. An Investigation of Power Stabilization and Space-Dependent Dynamics of a Nuclear Fluidized-Bed Reactor

    International Nuclear Information System (INIS)

    Pain, Christopher C.; Eaton, Matthew D.; Gomes, Jefferson L.M.A.; Oliveira, Cassiano R.E. de; Umpleby, Adrian P.; Ziver, Kemal; Ackroyd, Ron T.; Miles, Bryan; Goddard, Antony J.H.; Dam, H. van; Hagen, T.H.J.J. van der; Lathouwers, D.

    2003-01-01

    Previous work into the space-dependent kinetics of the conceptual nuclear fluidized bed has highlighted the sensitivity of fission power to particle movements within the bed. The work presented in this paper investigates a method of stabilizing the fission power by making it less sensitive to fuel particle movement. Steady-state neutronic calculations are performed to obtain a suitable design that is stable to radial and axial fuel particle movements in the bed. Detailed spatial/temporal simulations performed using the finite element transient criticality (FETCH) code investigate the dynamics of the new reactor design. A dual requirement of the design is that it has a moderate power output of ∼300 MW(thermal)

  3. Submicron and Nanoparticulate Matter Removal by HEPA-Rated Media Filters and Packed Beds of Granular Materials

    Science.gov (United States)

    Perry, J. L.; Agui, J. H.; Vijayakimar, R

    2016-01-01

    Contaminants generated aboard crewed spacecraft by diverse sources consist of both gaseous chemical contaminants and particulate matter. Both HEPA media filters and packed beds of granular material, such as activated carbon, which are both commonly employed for cabin atmosphere purification purposes have efficacy for removing nanoparticulate contaminants from the cabin atmosphere. The phenomena associated with particulate matter removal by HEPA media filters and packed beds of granular material are reviewed relative to their efficacy for removing fine (less than 2.5 micrometers) and ultrafine (less than 0.01 micrometers) sized particulate matter. Considerations are discussed for using these methods in an appropriate configuration to provide the most effective performance for a broad range of particle sizes including nanoparticulates.

  4. Optimization of operating parameters for gas-phase photocatalytic splitting of H2S by novel vermiculate packed tubular reactor.

    Science.gov (United States)

    Preethi, V; Kanmani, S

    2016-10-01

    Hydrogen production by gas-phase photocatalytic splitting of Hydrogen Sulphide (H2S) was investigated on four semiconductor photocatalysts including CuGa1.6Fe0.4O2, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2. The CdS and ZnS coated core shell particles (CdS + ZnS)/Fe2O3 shows the highest rate of hydrogen (H2) production under optimized conditions. Packed bed tubular reactor was used to study the performance of prepared photocatalysts. Selection of the best packing material is a key for maximum removal efficiency. Cheap, lightweight and easily adsorbing vermiculate materials were used as a novel packing material and were found to be effective in splitting H2S. Effect of various operating parameters like flow rate, sulphide concentration, catalyst dosage, light irradiation were tested and optimized for maximum H2 conversion of 92% from industrial waste H2S. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Continuous preparation of Fe3O4 nanoparticles through Impinging Stream-Rotating Packed Bed reactor and their electrochemistry detection toward heavy metal ions

    International Nuclear Information System (INIS)

    Fan, Hong-Lei; Zhou, Shao-Feng; Gao, Jing; Liu, You-Zhi

    2016-01-01

    We reported the continuous preparation and electrochemical behavior toward heavy metal ions of the Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs). This Fe 3 O 4 NPs were fabricated through a novel Impinging Stream-Rotating Packed Bed reactor with a high production rate of 2.23 kg/hour. The as-prepared Fe 3 O 4 NPs were quasi-spherical with a mean diameter of about 10 nm and shown the characteristics of superparamagnetism with the saturated magnetization of 60.5 emu/g. The electrochemical characterization of the as-prepared Fe 3 O 4 NPs toward heavy metal ions were evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The results indicated that the modified electrode could be used to individual detection of Pb(II), Cu(II), Hg(II) and Cd(II). In particular, the modified electrode exhibited the selective detection toward Pb(II) with higher sensitivity of 14.9 μA/μM, while the response to Cu(II), Hg(II) and Cd(II) were negligible. Besides, the modified electrode shown good stability and potential practical applicability in the electrochemical determination of Pb(II). This above results offered a simple method for continuous preparation sensing materials in the application field of electrochemical detection of toxic metal ions through the technology of process intensification. - Highlights: • Fe 3 O 4 nanoparticles were continuous prepared through IS-RPB reactor. • The Fe 3 O 4 nanoparticles showed selective detection of heavy metal ions. • It exhibited favorable sensitivity (14.9 μA μM −1 ) and LOD (0.119 μM) for Pb(II). • The as-prepared nanoparticles showed favorable potential application.

  6. A new fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Sefidvash, F.

    1986-01-01

    A new nuclear reactor design based on the fluidized bed concept is proposed. A current design utilizes spherical fuel of slightly enriched Zircaloy-clad uranium dioxide fluidized by light water under pressure. The reactor is modular in system; therefore, any size reactor can be constructed from the basic standard modul. The reactor physics calculations show that reactivity increases with porosity to a maximum value and thereafter decreases. This produces inherent safety and eliminates the need for control rods and burnable poisons. The heat transfer calculations show that the maximum power extracted from the reactor core is not limited to the material temperature limits but to the maximum mass flow of coolant, which corresponds to the desired operating porosity. Design simplicity and inherent safety make it an attractive small reactor design. (Author) [pt

  7. Theory and measurements of electrophoretic effects in monolith, fixed-bed, and fluidized-bed plasma reactors

    International Nuclear Information System (INIS)

    Morin, T.J.

    1989-01-01

    Pressure gradients and secondary flow fields generated by the passage of electrical current in a d.c. gas discharge or gas laser are topics of longstanding interest in the gaseous electronics literature. These hydrodynamic effects of space charge fields and charged particle density gradients have been principally exploited in the development of gas separation and purification processes. In recent characterization studies of fixed-bed and fluidized-bed plasma reactors several anomalous flow features have been observed. These reactors involve the contacting of a high-frequency, resonantly-sustained, disperse gas discharge with granular solids in a fixed or fluidized bed. Anomalies in the measured pressure drops and fluidization velocities have motivated the development of an appropriate theoretical approach to, and some additional experimental investigations of electrophoretic effects in disperse gas discharges. In this paper, a theory which includes the effects of space charge and diffusion is used to estimate the electric field and charged particle density profiles. These profiles are then used to calculate velocity fields and gas flow rates for monolith, fixed-bed, and fluidized-bed reactors. These results are used to rationalize measurements of gas flow rates and axial pressure gradients in high-frequency disperse gas discharges with and without an additional d.c. axial electric field

  8. Experimental study of flow field characteristics on bed configurations in the pebble bed reactor

    International Nuclear Information System (INIS)

    Jia, Xinlong; Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jia, Haijun; Jiang, Shengyao

    2017-01-01

    Highlights: • PTV study of flow fields of pebble bed reactor with different configurations are carried out. • Some criteria are proposed to quantify vertical velocity field and flow uniformity. • The effect of different pebble bed configurations is also compared by the proposed criteria. • The displacement thickness is used analogically to analyze flow field characteristics. • The effect of mass flow variation in the stagnated region of the funnel flow is measured. - Abstract: The flow field characteristics are of fundamental importance in the design work of the pebble bed high temperature gas cooled reactor (HTGR). The different effects of bed configurations on the flow characteristics of pebble bed are studied through the PTV (Particle Tracking Velocimetry) experiment. Some criteria, e.g. flow uniformity (σ) and mass flow level (α), are proposed to estimate vertical velocity field and compare the bed configurations. The distribution of the Δθ (angle difference between the individual particle velocity and the velocity vector sum of all particles) is also used to estimate the resultant motion consistency level. Moreover, for each bed configuration, the thickness of displacement is analyzed to measure the effect of the funnel flow zone based on the boundary layer theory. Detailed information shows the quantified characteristics of bed configuration effects on flow uniformity and other characteristics; and the sequence of levels of each estimation criterion is obtained for all bed configurations. In addition, a good design of the pebble bed configuration is suggested and these estimation criteria can be also applied and adopted in testing other geometry designs of pebble bed.

  9. 3D Model Studies on the Effect of Bed and Powder Type Upon Radial Static Pressure and Powder Distribution in Metallurgical Shaft Furnaces

    Directory of Open Access Journals (Sweden)

    Panic B.

    2017-09-01

    Full Text Available The flow of gases in metallurgical shaft furnaces has a decisive influence on the course and process efficiency. Radial changes in porosity of the bed cause uneven flow of gas along the radius of the reactor, which sometimes is deliberate and intentional. However, holdup of solid particles in descending packed beds of metallurgical shaft furnaces can lead to unintentional changes in porosity of the bed along the radial reactor. Unintentional changes in porosity often disrupt the flow of gas causing poor performance of the furnace. Such disruptions of flow may occur in the blast furnace due to high level of powder content in gas caused by large amount of coal dust/powder insufflated as fuel substitute. The paper describes the model test results of radial distribution of static pressure and powder hold up within metallurgical reactor. The measurements were carried out with the use of 3D physical model of two-phase flow gas-powder in the moving (descending packed bed. Sinter or blast furnace pellets were used as packed bed while carbon powder or iron powder were used as the powder. Wide diversity within both static pressure distribution and powder distribution along the radius of the reactor were observed once the change in the type of powder occurred.

  10. Preliminary Neutronic Design of High Burnup OTTO Cycle Pebble Bed Reactor

    OpenAIRE

    Setiadipura, T; Irwanto, D; Zuhair, Zuhair

    2015-01-01

    The pebble bed type High Temperature Gas-cooled Reactor (HTGR) is among the interesting nuclear reactor designs in terms of safety and flexibility for co-generation applications. In addition, the strong inherent safety characteristics of the pebble bed reactor (PBR) which is based on natural mechanisms improve the simplicity of the PBR design, in particular for the Once-Through-Then-Out (OTTO) cycle PBR design. One of the important challenges of the OTTO cycle PBR design, and nuclear reactor ...

  11. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment

    International Nuclear Information System (INIS)

    Lei, Yangming; Liu, Hong; Shen, Zhemin; Wang, Wenhua

    2013-01-01

    Highlights: • An electrochemical trickle bed reactor was composed of C-PTFE-coated graphite chips. • The trickle bed reactor had a high H 2 O 2 production rate in a dilute electrolyte. • An azo dye was effectively decomposed by the electro-Fenton process in the reactor. -- Abstract: To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H 2 O 2 was generated with a current of 0.3 A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte–cathode interface. In terms of H 2 O 2 generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L −1 of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3 h

  12. An improved theoretical electrochemical-thermal modelling of lithium-ion battery packs in electric vehicles

    Science.gov (United States)

    Amiribavandpour, Parisa; Shen, Weixiang; Mu, Daobin; Kapoor, Ajay

    2015-06-01

    A theoretical electrochemical thermal model combined with a thermal resistive network is proposed to investigate thermal behaviours of a battery pack. The combined model is used to study heat generation and heat dissipation as well as their influences on the temperatures of the battery pack with and without a fan under constant current discharge and variable current discharge based on electric vehicle (EV) driving cycles. The comparison results indicate that the proposed model improves the accuracy in the temperature predication of the battery pack by 2.6 times. Furthermore, a large battery pack with four of the investigated battery packs in series is simulated in the presence of different ambient temperatures. The simulation results show that the temperature of the large battery pack at the end of EV driving cycles can reach to 50 °C or 60 °C in high ambient temperatures. Therefore, thermal management system in EVs is required to maintain the battery pack within the safe temperature range.

  13. Celebrating 40 years anaerobic sludge bed reactors for industrial wastewater treatment

    NARCIS (Netherlands)

    Van Lier, J.B.; Van der Zee, F.P.; Frijters, C.T.M.J.; Ersahin, M.E.

    2015-01-01

    In the last 40 years, anaerobic sludge bed reactor technology evolved from localized lab-scale trials to worldwide successful implementations at a variety of industries. High-rate sludge bed reactors are characterized by a very small foot print and high applicable volumetric loading rates. Best

  14. Raising distillate selectivity and catalyst life time in Fischer-Tropsch synthesis by using a novel dual-bed reactor

    International Nuclear Information System (INIS)

    Tavasoli, A.; Sadaghiani, K.; Khodadadi, A. A.; Mortazavi, Y.

    2007-01-01

    In a novel dual bed reactor Fischer-Tropsch synthesis was studied by using two diff rent cobalt catalysts. An alkali-promoted cobalt catalyst was used in the first bed of a fixed-bed reactor followed by a Raiment promoted cobalt catalyst in the second bed. The activity, product selectivity and accelerated deactivation of the system were assessed and compared with a conventional single bed reactor system. The methane selectivity in the dual-bed reactor was about 18.9% less compared to that of the single-bed reactor. The C 5+ selectivity for the dual-bed reactor was 10.9% higher than that of the single-bed reactor. Accelerated deactivation of the catalysts in the dual-bed reactor was 42% lower than that of the single-bed reactor. It was revealed that the amount of catalysts activity recovery after regeneration at 400 d eg C in the dual-bed system is higher than that of the single-bed system

  15. Thermal valorization of post-consumer film waste in a bubbling bed gasifier

    International Nuclear Information System (INIS)

    Martínez-Lera, S.; Torrico, J.; Pallarés, J.; Gil, A.

    2013-01-01

    Highlights: • Film waste from packaging is a common waste, a fraction of which is not recyclable. • Gasification can make use of the high energy value of the non-recyclable fraction. • This waste and two reference polymers were gasified in a bubbling bed reactor. • This experimental research proves technical feasibility of the process. • It also analyzes impact of composition and ER on the performance of the plant. - Abstract: The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m 3 and cold gas efficiencies up to 60%

  16. 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

  17. X-ray digital industrial radiography (DIR) for local liquid velocity (VLL) measurement in trickle bed reactors (TBRs): Validation of the technique

    International Nuclear Information System (INIS)

    Mohd Salleh, Khairul Anuar; Lee, Hyoung Koo; Rahman, Mohd Fitri Abdul; Al Dahhan, Muthanna H.

    2014-01-01

    Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (V LL ) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the V LL within TBRs

  18. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  19. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yangming [Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China); School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Hong, E-mail: liuhong@cigit.ac.cn [Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China); Shen, Zhemin, E-mail: zmshen@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Wenhua [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-10-15

    Highlights: • An electrochemical trickle bed reactor was composed of C-PTFE-coated graphite chips. • The trickle bed reactor had a high H{sub 2}O{sub 2} production rate in a dilute electrolyte. • An azo dye was effectively decomposed by the electro-Fenton process in the reactor. -- Abstract: To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H{sub 2}O{sub 2} was generated with a current of 0.3 A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte–cathode interface. In terms of H{sub 2}O{sub 2} generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L{sup −1} of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3 h.

  20. Improved oxidation of air pollutants in a non-thermal plasma

    International Nuclear Information System (INIS)

    Roland, U.; Holzer, F.; Kopinke, F.-D.

    2002-01-01

    The performance of non-thermal plasma (NTP) for the removal of organic air pollutants (especially in low concentrations) is improved by the introduction of ferroelectric and catalytically active materials into the discharge zone of an NTP reactor. Experiments with model systems (various contaminants and packed-bed materials) have shown that such a modification of a homogeneous gas-phase plasma can overcome the most serious restrictions of the NTP technique at its present state of the art: the incomplete total oxidation (i.e. the low selectivity to CO 2 ) and the energetic inefficiency. Placing a ferroelectric packed-bed material in the discharge zone was shown to result in a lowering of the energy input required. The main effects of plasma catalysis enabled by the introduction of a catalytically active material were an enhanced conversion of pollutants and a higher CO 2 selectivity. These improvements are based on the presence of short-lived oxidising species in the inner volume of porous catalysts. Additionally, the formation of a reservoir of adsorbed oxidants in the NTP zone could be shown. The combination of both modifications (ferroelectric packed-bed materials and plasma catalysis) is a promising method to support the NTP-initiated oxidation of air pollutants

  1. A particle bed reactor based NTP in the 112,500 N thrust class

    International Nuclear Information System (INIS)

    Ludewig, H.; Powell, J.R.; Lazareth, O.W. Jr.; Todosow, M.

    1993-01-01

    This paper discusses the application of a Particle Bed Reactor (PBR) to a 112,500 N thrust Nuclear Thermal Propulsion (NTP) Engine. The method of analysis is described, followed by a presentation of the results. It is concluded that the PBR would result in a very competitive NTP engine. In addition, due to the high power densities possible with a PBR, high thrust/weight ratios are possible. This conclusion can be used to satisfy a variety of mission goals

  2. A particle bed reactor based NTP in the 112,500 N thrust class

    Science.gov (United States)

    Ludewig, Hans; Powell, James R.; Lazareth, Otto W.; Todosow, Michael

    1993-01-01

    This paper discusses the application of a Particle Bed Reactor (PBR) to a 112,500 N thrust Nuclear Thermal Propulsion (NTP) Engine. The method of analysis is described, followed by a presentation of the results. It is concluded that the PBR would result in a very competitive NTP engine. In addition, due to the high power densities possible with a PBR, high thrust/weight ratios are possible. This conclusion can be used to satisfy a variety of mission goals.

  3. Mechanical and Structural Behavior of Granular Material Packed Beds for Space Life Support System Applications

    Science.gov (United States)

    Malla, Ramesh B.; Anandakumar, Ganesh

    2005-01-01

    Long-term human mission to space, such as living in International Space Station (ISS), Lunar, and Martian bases, and travel to Mars, must m ake use of Advanced Life Support Systems (ALSS) to generate and recycle critical life supporting elements like oxygen and water. Oxygen Gen eration Assembly (OGA) and Water Processor Assembly (WPA), critical c omponents of ALSS, make use of series of granular material packed beds for generation and recycling of oxygen and water. Several granular m aterials can be used for generation, recycling, processing and recovery of oxygen and water. For example, they may include soft bed media, e.g. ion exchange resins for oxygen generation assembly and hard bed media such as, activated alumina, magchem (Magnesium oxide) and activa ted carbon to remove organic species like ethanol, methanol, and urea from wastewater in Water recovery/processing assembly. These beds are generally packed using a plate-spring mechanism to provide sufficien t compaction to the bed media throughout the course of operation. This paper presents results from an experimental study of a full-scale, 3 8.1 cm (15 inches) long and 3.7 cm (1.44 inches) diameter. activated alumina bed enclosed in a cylinder determining its force-displacement behavior, friction mobilizing force, and axial normal stress distribu tion under various axially applied loads and at different levels of packing. It is observed that force-displacement behavior is non-linear for low compaction level and becomes linear with increase in compaction of the bed media. Axial normal stress distribution along the length of the bed media decreased non-linearly with increase in depth from the loading end of the granular media. This paper also presents experimental results on the amount of particulates generated corresponding to various compaction levels. Particulates generated from each of the tests were measured using standard US sieves. It was found that the p articulates and the overall displacement of

  4. Continuous Heterogeneous Photocatalysis in Serial Micro-Batch Reactors.

    Science.gov (United States)

    Pieber, Bartholomäus; Shalom, Menny; Antonietti, Markus; Seeberger, Peter H; Gilmore, Kerry

    2018-01-29

    Solid reagents, leaching catalysts, and heterogeneous photocatalysts are commonly employed in batch processes but are ill-suited for continuous-flow chemistry. Heterogeneous catalysts for thermal reactions are typically used in packed-bed reactors, which cannot be penetrated by light and thus are not suitable for photocatalytic reactions involving solids. We demonstrate that serial micro-batch reactors (SMBRs) allow for the continuous utilization of solid materials together with liquids and gases in flow. This technology was utilized to develop selective and efficient fluorination reactions using a modified graphitic carbon nitride heterogeneous catalyst instead of costly homogeneous metal polypyridyl complexes. The merger of this inexpensive, recyclable catalyst and the SMBR approach enables sustainable and scalable photocatalysis. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Anaerobic treatment of winery wastewater in fixed bed reactors.

    Science.gov (United States)

    Ganesh, Rangaraj; Rajinikanth, Rajagopal; Thanikal, Joseph V; Ramanujam, Ramamoorty Alwar; Torrijos, Michel

    2010-06-01

    The treatment of winery wastewater in three upflow anaerobic fixed-bed reactors (S9, S30 and S40) with low density floating supports of varying size and specific surface area was investigated. A maximum OLR of 42 g/l day with 80 +/- 0.5% removal efficiency was attained in S9, which had supports with the highest specific surface area. It was found that the efficiency of the reactors increased with decrease in size and increase in specific surface area of the support media. Total biomass accumulation in the reactors was also found to vary as a function of specific surface area and size of the support medium. The Stover-Kincannon kinetic model predicted satisfactorily the performance of the reactors. The maximum removal rate constant (U(max)) was 161.3, 99.0 and 77.5 g/l day and the saturation value constant (K(B)) was 162.0, 99.5 and 78.0 g/l day for S9, S30 and S40, respectively. Due to their higher biomass retention potential, the supports used in this study offer great promise as media in anaerobic fixed bed reactors. Anaerobic fixed-bed reactors with these supports can be applied as high-rate systems for the treatment of large volumes of wastewaters typically containing readily biodegradable organics, such as the winery wastewater.

  6. Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

    Energy Technology Data Exchange (ETDEWEB)

    Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

    2013-08-15

    One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

  7. Study on effective particle diameters and coolability of particulate beds packed with irregular multi-size particles

    International Nuclear Information System (INIS)

    Thakre, S.; Ma, W.; Kudinov, P.; Bechta, S.

    2013-08-01

    One of the key questions in severe accident research is the coolability of the debris bed, i.e., whether decay heat can be completely removed by the coolant flow into the debris bed. Extensive experimental and analytical work has been done to substantiate the coolability research. Most of the available experimental data is related to the beds packed with single size (mostly spherical) particles, and less data is available for multi-size/irregular-shape particles. There are several analytical models available, which rely on the mean particle diameter and porosity of the bed in their predictions. Two different types of particles were used to investigate coolability of particulate beds at VTT, Finland. The first type is irregular-shape Aluminum Oxide gravel particles whose sizes vary from 0.25 mm to 10 mm, which were employed in the STYX experiment programme (2001-2008). The second type is spherical beads of Zirconium silicate whose sizes vary between 0.8 mm to 1 mm, which were used in the COOLOCE tests (Takasuo et al., 2012) to study the effect of multi-dimensional flooding on coolability. In the present work, the two types of particles are used in the POMECO-FL and POMECO-HT test facility to obtain their effective particle diameters and dryout heat flux of the beds, respectively. The main idea is to check how the heaters' orientations (vertical in COOLOCE vs. horizontal in POMECO-HT) and diameters (6 mm in COOLOCE vs. 3 mm in POMECO-HT) affect the coolability (dryout heat flux) of the test beds. The tests carried out on the POMECO-FL facility using a bed packed with aluminum oxide gravel particles show the effective particle diameter of the gravel particles is 0.65 mm, by which the frictional pressure gradient can be predicted by the Ergun equation. After the water superficial velocity is higher than 0.0025 m/s, the pressure gradient is underestimated. The effective particle diameter of the zirconium particles is found as 0.8 mm. The dryout heat flux is measured on

  8. Pebble bed reactors simulation using MCNP: The Chinese HTR-10 reactor

    Directory of Open Access Journals (Sweden)

    SA Hosseini

    2013-09-01

    Full Text Available   Given the role of Gas-Graphite reactors as the fourth generation reactors and their recently renewed importance, in 2002 the IAEA proposed a set of Benchmarking problems. In this work, we propose a model both efficient in time and resources and exact to simulate the HTR-10 reactor using MCNP-4C code. During the present work, all of the pressing factors in PBM reactor design such as the inter-pebble leakage, fuel particle distribution and fuel pebble packing fraction effects have been taken into account to obtain an exact and easy to run model. Finally, the comparison between the results of the present work and other calculations made at INEEL proves the exactness of the proposed model.

  9. Mean ascending velocity of powder entrained by gas in a packed bed; Juten sonai ni okeru kiryu ni dohansareru funtai no heikin josho sokudo

    Energy Technology Data Exchange (ETDEWEB)

    Ariyama, T; Sato, M; Asakawa, Y [NKK Corp., Tokyo (Japan)

    1996-01-20

    For the purpose of clarifying the behavior of fine particles entrained by upward gas in the packed bed like in a blast furnace, the mean ascending velocity of powder in the packed bed was measured by the residence time distribution of the tracer powder. According the results, it was found that the measured velocity was lower than the values predicted by the successive collision model of fine particles. The difference is considered to be caused by the stagnant zone of fine particles on the packed materials, and this behavior was confirmed by the observation in the two dimensional experimental apparatus. Namely, the dynamic hold-up of powder in the packed bed was composed of the particles entrained by the upward gas and the stagnant particles on the packed material, and the latter part was successively renewed by the powder carried by gas. Then, on the basis of the above results, the relation between stagnant time and local ascending velocity were experimentally correlated with solid-gas loading ratio, and it was found that there exists a certain relation among them. The model proposed by these experiments enabled to calculate the mean ascending velocity of powder in the packed bed. 6 refs., 11 figs., 1 tab.

  10. Analytical calculation of the fuel temperature reactivity coefficient for pebble bed and prismatic high temperature reactors for plutonium and uranium-thorium fuels

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology - KTH, Roslagstullsbacken 21, S-10691 Stockholm (Sweden)]. E-mail: alby@anl.gov

    2007-01-15

    We analytically evaluated the fuel coefficient of temperature both for pebble bed and prismatic high temperature reactors when they utilize as fuel plutonium and minor actinides from light water reactors spent fuel or a mixture of 50% uranium, enriched 20% in {sup 235}U, and 50% thorium. In both cores the calculation involves the evaluation of the resonances integrals of the high absorbers fuel nuclides {sup 240}Pu, {sup 238}U and {sup 232}Th and it requires the esteem of the Dancoff-Ginsburg factor for a pebble bed or prismatic core. The Dancoff-Ginsburg factor represents the only discriminating parameter in the results for the two different reactors types; in fact, both the pebble bed and the prismatic reactors share the same the pseudo-cross-section describing an infinite medium made of graphite filled by TRISO particles. We considered only the resolved resonances with a statistical spin factor equal to one and we took into account 267, 72, 212 resonances in the range 1.057-5692, 6.674-14485, 21.78-3472 eV for {sup 240}Pu, {sup 238}U and {sup 232}Th, respectively, for investigating the influence on the fuel temperature reactivity coefficient of the variation of the TRISO kernel radius and TRISO particles packing fraction from 100, 200 to 300 {mu}m and from 10% to 50%, respectively. Finally, in the pebble bed core, we varied the radius of the pebble for setting a fuel temperature reactivity coefficient similar to the one of a prismatic core.

  11. 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

  12. Burnup performance of OTTO cycle pebble bed reactors with ROX fuel

    International Nuclear Information System (INIS)

    Ho, Hai Quan; Obara, Toru

    2015-01-01

    Highlights: • A 300 MW t Small Pebble Bed Reactor with Rock-like oxide fuel is proposed. • Using ROX fuel can achieve high discharged burnup of spent fuel. • High geological stability can be expected in direct disposal of the spent ROX fuel. • The Pebble Bed Reactor with ROX fuel can be critical at steady state operation. • All the reactor designs have a negative temperature coefficient. - Abstract: A pebble bed high-temperature gas-cooled reactor (PBR) with rock-like oxide (ROX) fuel was designed to achieve high discharged burnup and improve the integrity of the spent fuel in geological disposal. The MCPBR code with a JENDL-4.0 library, which developed the analysis of the Once-Through-Then-Out (OTTO) cycle in PBR, was used to perform the criticality and burnup analysis. Burnup calculations for eight cases were carried out for both ROX fuel and a UO 2 fuel reactor with different heavy-metal loading conditions. The effective multiplication factor of all cases approximately equalled unity in the equilibrium condition. The ROX fuel reactor showed lower FIFA than the UO 2 fuel reactor at the same heavy-metal loading, about 5–15%. However, the power peaking factor and maximum power per fuel ball in the ROX fuel core were lower than that of UO 2 fuel core. This effect makes it possible to compensate for the lower-FIFA disadvantage in a ROX fuel core. All reactor designs had a negative temperature coefficient that is needed for the passive safety features of a pebble bed reactor

  13. Theoretical and experimental research of natural convection in the core of the high temperature pebble bed reactor

    International Nuclear Information System (INIS)

    Schuerenkraemer, M.

    1984-04-01

    The physical model of the developed THERMIX-2D-code for computing thermohydraulic behaviour of the core of high temperature pebble bed reactors is verified by experiments with natural convection flow. Such fluid flow behaviour can be of very high importance for the real reactor in the case of natural heat removal decay. The experiments are performed in a special set up testing-stand with pressures up to 30 bars and temperatures up to 300 0 C by using air and helium as fluid. In comparison with the experimental data the numerical results show that a good and useful simulation is given by the program. Pure natural convection flow in packed pebble beds is calculated with a very high degree of reliability. The investigation of flow stability demonstrate that radial-symmetric relations are not given temporarily when national convection is overlayed by forced convection flow. In the discussion it is explained when and to what extent the program leds to useful results in such situations. The test of the effective heat conductivity lambdasub(eff) results in an improvement of the lambdasub(eff)-data used so far for temperatures below 1300 0 C. (orig.) [de

  14. An Approach for Designing Thermal Management Systems for Electric and Hybrid Vehicle Battery Packs

    International Nuclear Information System (INIS)

    Pesaran, Ahmad A.; Keyser, Matthew; Burch, Steve

    1999-01-01

    If battery packs for electric vehicles (EVs) and hybrid electric vehicles (HEVs) are to operate effectively in all climates, thermal management of the packs is essential. In this paper, we will review a systematic approach for designing and evaluating battery pack thermal management systems. A thermal management system using air as the heat transfer medium is less complicated than a system using liquid cooling/heating. Generally, for parallel HEVs, an air thermal management system is adequate, whereas for EVs and series HEVs, liquid-based systems may be required for optimum thermal performance. Further information on battery thermal management can be found on the Web site www.ctts.nrel.gov/BTM

  15. High thermal performance lithium-ion battery pack including hybrid active–passive thermal management system for using in hybrid/electric vehicles

    International Nuclear Information System (INIS)

    Fathabadi, Hassan

    2014-01-01

    In this study, a novel Li-ion battery pack design including hybrid active–passive thermal management system is presented. The battery pack is suitable for using in hybrid/electric vehicles. Active part of the hybrid thermal management system uses distributed thin ducts, air flow and natural convection as cooling media while the passive part utilizes phase change material/expanded graphite composite (PCM/EG) as cooling/heating component to optimize the thermal performance of the proposed battery pack. High melting enthalpy of PCM/EG composite together with melting of PCM/EG composite at the temperature of 58.9 °C remains the temperature distribution of the battery units in the desired temperature range (below 60 °C). The temperature and voltage distributions in the proposed battery pack design consisting of battery units, distributed thin ducts and PCM/EG composite are calculated by numerical solving of the related partial differential equations. Simulation results obtained by writing M-files code in Matlab environment and plotting the numerical data are presented to validate the theoretical results. A comparison between the thermal and physical characteristics of the proposed battery pack and other latest works is presented that explicitly proves the battery pack performance. - Highlights: • Novel Li-ion battery pack including active and passive thermal management systems. • The battery pack has high thermal performance for ambient temperatures until 55 °C. • Uniform temperature and voltage distributions. • The maximum observed temperature in each battery unit is less than other works. • The maximum temperature dispersion in each battery is less than other works

  16. Characterization of an immobilized cell, trickle bed reactor during long term butanol (ABE) fermentation.

    Science.gov (United States)

    Park, C H; Okos, M R; Wankat, P C

    1990-06-20

    Acetone-butanol-ethanol (ABE) fermentation was performed continuously in an immobilized cell, trickle bed reactor for 54 days without, degeneration by maintaining the pH above 4.3. Column clogging was minimized by structured packing of immobilization matrix. The reactor contained two serial glass columns packed with Clostridium acetobutylicum adsorbed on 12- and 20-in.-long polyester sponge strips at total flow rates between 38 and 98.7 mL/h. Cells were initially grown at 20 g/L glucose resulting in low butanol (1.15 g/L) production encouraging cell growth. After the initial cell growth phase a higher glucose concentration (38.7 g/L) improved solvent yield from 13.2 to 24.1 wt%, and butanol production rate was the best. Further improvement in solvent yield and butanol production rate was not observed with 60 g/L of glucose. However, when the fresh nutrient supply was limited to only the first column, solvent yield increased to 27.3 wt% and butanol selectivity was improved to 0.592 as compared to 0.541 when fresh feed was fed to both columns. The highest butanol concentration of 5.2 g/L occurred at 55% conversion of the feed with 60 g/L glucose. Liquid product yield of immobilized cells approached the theoretical value reported in the literature. Glucose and product concentration profiles along the column showed that the columns can be divided into production and inhibition regions. The length of each zone was dependent upon the feed glucose concentration and feed pattern. Unlike batch fermentation, there was no clear distinction between acid and solvent production regions. The pH dropped, from 6.18-6.43 to 4.50-4.90 in the first inch of the reactor. The pH dropped further to 4.36-4.65 by the exit of the column. The results indicate that the strategy for long term stable operation with high solvent yield requires a structured packing of biologically stable porous matrix such as polyester sponge, a pH maintenance above 4.3, glucose concentrations up to 60 g/L and

  17. Flow instability tests for a particle bed reactor nuclear thermal rocket fuel element

    Science.gov (United States)

    Lawrence, Timothy J.

    1993-05-01

    Recent analyses have focused on the flow stability characteristics of a particle bed reactor (PBR). These laminar flow instabilities may exist in reactors with parallel paths and are caused by the heating of the gas at low Reynolds numbers. This phenomena can be described as follows: several parallel channels are connected at the plenum regions and are stabilized by some inlet temperature and pressure; a perturbation in one channel causes the temperature to rise and increases the gas viscosity and reduces the gas density; the pressure drop is fixed by the plenum regions, therefore, the mass flow rate in the channel would decrease; the decrease in flow reduces the ability to remove the energy added and the temperature increases; and finally, this process could continue until the fuel element fails. Several analyses based on different methods have derived similar curves to show that these instabilities may exist at low Reynolds numbers and high phi's ((Tfinal Tinitial)/Tinitial). These analyses need to be experimentally verified.

  18. Thermal valorization of post-consumer film waste in a bubbling bed gasifier.

    Science.gov (United States)

    Martínez-Lera, S; Torrico, J; Pallarés, J; Gil, A

    2013-07-01

    The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m3 and cold gas efficiencies up to 60%. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Experimental research of pressure drop in packed beds of monosized spheres a novel correlation for pressure drop calculation

    Directory of Open Access Journals (Sweden)

    Stamenić Mirjana S.

    2017-01-01

    Full Text Available Flow through packed beds of spheres is a complex phenomenon and it has been extensively studied. Although, there is many different correlations there is still no reliable universal equation for prediction of pressure drop. The paper presents the results of experimental research of pressure drop in packed bed of monosized spheres of three different diameters, 8, 11, and 13 mm set within cylindrical vessel of diameter dk = 74 mm, and two different heights of packed bed, hs = 300 and 400 mm. It has been proposed modification of widely used Ergun’s equation in the form of fp = [150+1.3•(Rep/(1-ε]•(1-ε2/(ε3×Rep and new correlation fp = 1/[(27.4-25700•dh/Rep+0.545+6.85•dh] for pressure drop calculation in simple and convenient form for hand and computer calculations. For total number of 362 experimental runs the correlation ratio of the modified Ergun’s relation was CR = 99.3%, and standard deviation SD = 12.2%, while novel relation has CR = 93.7% and SD = 5.4%. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 33049

  20. X-ray digital industrial radiography (DIR) for local liquid velocity (V(LL)) measurement in trickle bed reactors (TBRs): validation of the technique.

    Science.gov (United States)

    Mohd Salleh, Khairul Anuar; Rahman, Mohd Fitri Abdul; Lee, Hyoung Koo; Al Dahhan, Muthanna H

    2014-06-01

    Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (V(LL)) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the V(LL) within TBRs.

  1. Thermal decomposition of selected chlorinated hydrocarbons during gas combustion in fluidized bed

    Directory of Open Access Journals (Sweden)

    Olek Malgorzata

    2013-01-01

    Full Text Available Abstract Background The process of thermal decomposition of dichloromethane (DCM and chlorobenzene (MCB during the combustion in an inert, bubbling fluidized bed, supported by LPG as auxiliary fuel, have been studied. The concentration profiles of C6H5CI, CH2Cl2, CO2, CO, NOx, COCl2, CHCl3, CH3Cl, C2H2, C6H6, CH4 in the flue gases were specified versus mean bed temperature. Results The role of preheating of gaseous mixture in fluidized bed prior to its ignition inside bubbles was identified as important factor for increase the degree of conversion of DCM and MCB in low bed temperature, in comparison to similar process in the tubular reactor. Conclusions Taking into account possible combustion mechanisms, it was identified that autoignition in bubbles rather than flame propagation between bubbles is needed to achieve complete destruction of DCM and MCB. These condition occurs above 900°C causing the degree of conversion of chlorine compounds of 92-100%.

  2. Local liquid velocity measurement in trickle bed reactors (TBRs) using the x-ray digital industrial radiography (DIR) technique

    Science.gov (United States)

    Anuar Mohd Salleh, Khairul; Lee, Hyoung Koo; Al-Dahhan, Muthanna H.

    2014-01-01

    This work describes the development of a new technique to measure local liquid velocity (VLL) for multiphase flows in trickle bed reactors (TBRs) (gas-liquid-solid system). In the studied TBR, the liquid phase is represented by water, gas by air and 3 mm expanded polystyrene beads as the solid packing. Three different superficial liquid velocities (VSL) and a constant superficial gas velocity (VSG) were used in the packed bed with an internal diameter of 4.25 cm. While the liquid is moving into the packed bed, tracking particles of 106-125 μm diameter (16.45% difference) are injected. The movement of the tracking particles is monitored and digitally recorded by a complementary metal-oxide-semiconductor detector. In this experiment, x-rays were used as the radiation source. Four replications were made with fresh packing. Comparable observations can be found from other published techniques (i.e. magnetic resonance imaging). Results from this study indicate that, at VSL = 0.13 cm s-1, the measured VLL can reach up to 51 times that of its VSL, while for VSL = 0.27 cm s-1, the measured VLL reached up to 35 times higher than the VSL and for VSL = 0.39 cm s-1, the VLL reached up to 39.8 times higher than its VSL. Through statistical analysis, the implementation of such a method is found to be reproducible throughout the experiments. The mean per cent difference in the measured VLL was 10% and 5% for lower implemented VSL of 0.13 and 0.27 cm s-1, respectively. At higher VSL (0.39 cm s-1), the particle tracer was greatly distributed and carried away by the high liquid flow rate. The variance or the range of the measured VLL does not vary for all replications in every VSL, which confirms the reproducibility of the experimental measurements, regardless of the VSL.

  3. Nonproliferation and safeguard considerations: Pebble Bed reactor fuel cycle evaluation

    International Nuclear Information System (INIS)

    1978-09-01

    Nuclear fuel cycles were evaluated for the Pebble Bed Gas Cooled Reactor under development in the Federal Republic of Germany. The basic fuel cycle specified for the HTR-K and PNP is well qualified and will meet the requirements of these reactors. Twenty alternate fuel cycles are described, including high-conversion cycles, net-breeding cycles, and proliferation-resistant cycles. High-conversion cycles, which have a high probability of being successfully developed, promise a significant improvement in resource utilization. Proliferation-resistant cycles, also with a high probability of successful development, conpare very favorably with those for other types of reactors. Most of the advanced cycles could be adapted to first-generation pebble bed reactors with no significant modifications

  4. Pathways of 3-biofules (hydrogen, ethanol and methane) production from petrochemical industry wastewater via anaerobic packed bed baffled reactor inoculated with mixed culture bacteria

    International Nuclear Information System (INIS)

    Elreedy, Ahmed; Tawfik, Ahmed; Enitan, Abimbola; Kumari, Sheena; Bux, Faizal

    2016-01-01

    Highlights: • Bio-energy production from MEG contaminated wastewater via AnPBBR, was assessed. • Maximum concurrent H_2 and CH_4 production of 6.57 and 3.57 L/d were obtained. • Maximum ethanol generation of 237.13 mg/L was observed at a HRT of 9 h. • At OLRs up to 4 gCOD/L/d, MEG biodegradability of 71–98% was achieved. • AnPBBR economically achieved shorter payback period (6.25 y), compared to ABR. - Abstract: Simultaneous production of 3-biofuels (hydrogen, ethanol and methane) as by-products of the biodegradation of petrochemical wastewater containing MEG via anaerobic packed bed baffled reactor (AnPBBR), was extensively investigated. A four-chambered reactor supported by polyurethane sheets, was operated at a constant hydraulic retention time (HRT) of 36 h and different organic loading rates (OLRs) of 0.67, 1, 2 and 4 gCOD/L/d. The maximum specific H_2 and CH_4 production rates of 438.07 ± 43.02 and 237.80 ± 21.67 ml/L/d were respectively achieved at OLR of 4 gCOD/L/d. The residual bio-ethanol significantly increased from 57.15 ± 2.31 to 240.19 ± 34.69 mg/L at increasing the OLR from 0.67 to 4 gCOD/L/d, respectively. The maximum MEG biodegradability of 98% was attained at the lowest OLR. Compartment-wise profiles revealed that the maximum H_2 and ethanol production were achieved at HRT of 9 h (1st compartment), while the CH_4 production was peaked at HRTs of 27 and 36 h (last two compartments). Kinetic studies using Stover–Kincannon and completely stirred tank reactor (CSTR) in series models were successfully applied to the AnPBBR overall and compartment-to-compartment performance, respectively. The economic evaluation strongly revealed the potentials of using AnPBBR for simultaneous treatment and bio-energy production from petrochemical wastewater as compared to the classical anaerobic baffled reactor (ABR). Microbial analysis using Illumina MiSeq sequencing showed a diversity of bacterial community in AnPBBR. Proteobacteria (36

  5. Optimum cadmium reactor designs for colorimetric determination of nitrate with flow injection and gas-segmented continuous flow analyzers

    International Nuclear Information System (INIS)

    Patton, C.J.

    1989-01-01

    Cadmium reactor types can be grouped into four categories: packed bed; filamentous; open tubular; and planar. Packed bed cadmium reactors, in the form of cadmium filings, granules, powder, or electrolytically precipitated needles packed into glass or polymeric tubes, are by far the most widely used for both FIA and CFA methods. Surprisingly, filamentous cadmium reactors, in the form of cadmium wire slipped into flexible polymeric tubing, have been reported for CFA applications only. Open tubular cadmium reactors, in the form of small diameter cadmium tubing coiled into a helix, have been fully characterized and described for CFA applications. A preliminary description of planar cadmium reactors, in the form of cadmium foil sandwiched between continuous flow dialyzer blocks has also been reported. In this presentation, each reactor type is evaluated in terms of cost, ease of use, reduction efficiency, and long-term stability. Factors that make some reactors more applicable to FIA than to CFA (or the reverse) are also discussed, and experimental data are presented

  6. Final Report on Utilization of TRU TRISO Fuel as Applied to HTR Systems Part I: Pebble Bed Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Brian Boer; Abderrafi M. Ougouag

    2011-03-01

    The Deep-Burn (DB) concept [ ] focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400) [ ]. Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no

  7. Final Report on Utilization of TRU TRISO Fuel as Applied to HTR Systems Part I: Pebble Bed Reactors

    International Nuclear Information System (INIS)

    Boer, Brian; Ougouag, Abderrafi M.

    2011-01-01

    The Deep-Burn (DB) concept focuses on the destruction of transuranic nuclides from used light water reactor (LWR) fuel. These transuranic nuclides are incorporated into tri-isotopic (TRISO) coated fuel particles and used in gas-cooled reactors with the aim of a fractional fuel burnup of 60 to 70% in fissions per initial metal atom (FIMA). This high performance is expected through the use of multiple recirculation passes of the fuel in pebble form without any physical or chemical changes between passes. In particular, the concept does not call for reprocessing of the fuel between passes. In principle, the DB pebble bed concept employs the same reactor designs as the presently envisioned low-enriched uranium core designs, such as the 400 MWth Pebble Bed Modular Reactor (PBMR-400). Although it has been shown in the previous Fiscal Year (FY) (2009) that a PuO2 fueled pebble bed reactor concept is viable, achieving a high fuel burnup while remaining within safety-imposed prescribed operational limits for fuel temperature, power peaking, and temperature reactivity feedback coefficients for the entire temperature range, is challenging. The presence of the isotopes 239Pu, 240Pu, and 241Pu that have resonances in the thermal energy range significantly modifies the neutron thermal energy spectrum as compared to a standard, UO2-fueled core. Therefore, the DB pebble bed core exhibits a relatively hard neutron energy spectrum. However, regions within the pebble bed that are near the graphite reflectors experience a locally softer spectrum. This can lead to power and temperature peaking in these regions. Furthermore, a shift of the thermal energy spectrum with increasing temperature can lead to increased absorption in the resonances of the fissile Pu isotopes. This can lead to a positive temperature reactivity coefficient for the graphite moderator under certain operating conditions. Regarding the coated particle performance, the FY 2009 investigations showed that no significant

  8. THR-TH: a high-temperature gas-cooled nuclear reactor core thermal hydraulics code

    International Nuclear Information System (INIS)

    Vondy, D.R.

    1984-07-01

    The ORNL version of PEBBLE, the (RZ) pebble bed thermal hydraulics code, has been extended for application to a prismatic gas cooled reactor core. The supplemental treatment is of one-dimensional coolant flow in up to a three-dimensional core description. Power density data from a neutronics and exposure calculation are used as the basic information for the thermal hydraulics calculation of heat removal. Two-dimensional neutronics results may be expanded for a three-dimensional hydraulics calculation. The geometric description for the hydraulics problem is the same as used by the neutronics code. A two-dimensional thermal cell model is used to predict temperatures in the fuel channel. The capability is available in the local BOLD VENTURE computation system for reactor core analysis with capability to account for the effect of temperature feedback by nuclear cross section correlation. Some enhancements have also been added to the original code to add pebble bed modeling flexibility and to generate useful auxiliary results. For example, an estimate is made of the distribution of fuel temperatures based on average and extreme conditions regularly calculated at a number of locations

  9. THR-TH: a high-temperature gas-cooled nuclear reactor core thermal hydraulics code

    Energy Technology Data Exchange (ETDEWEB)

    Vondy, D.R.

    1984-07-01

    The ORNL version of PEBBLE, the (RZ) pebble bed thermal hydraulics code, has been extended for application to a prismatic gas cooled reactor core. The supplemental treatment is of one-dimensional coolant flow in up to a three-dimensional core description. Power density data from a neutronics and exposure calculation are used as the basic information for the thermal hydraulics calculation of heat removal. Two-dimensional neutronics results may be expanded for a three-dimensional hydraulics calculation. The geometric description for the hydraulics problem is the same as used by the neutronics code. A two-dimensional thermal cell model is used to predict temperatures in the fuel channel. The capability is available in the local BOLD VENTURE computation system for reactor core analysis with capability to account for the effect of temperature feedback by nuclear cross section correlation. Some enhancements have also been added to the original code to add pebble bed modeling flexibility and to generate useful auxiliary results. For example, an estimate is made of the distribution of fuel temperatures based on average and extreme conditions regularly calculated at a number of locations.

  10. DEGRADATION OF AROMATIC COMPOUNDS USING MOVING BED BIOFILM REACTORS

    Directory of Open Access Journals (Sweden)

    B. Ayati, H. Ganjidoust, M. Mir Fattah

    2007-04-01

    Full Text Available For biological treatment of water, there are many different biofilm systems in use. Examples of them are trickling filters, rotating biological contactors, fixed media submerged biofilters, granular media biofilters and fluidized bed reactors. They all have their advantages and disadvantages. Hence, the Moving Bed Biofilm Reactor process was developed in Norway in the late 1980s and early 1990s to adopt the best features of the activated sludge process as well as those of the biofilter processes, without including the worst. Two cylindrical moving bed biofilm reactors were used in this study working in upflow stream conditions. Experiments have been done in aerobic batch flow regime. Laboratory experiments were conducted at room temperature (23–28C and synthetic wastewater comprising a composition of phenol and hydroquinone in each reactor as the main organic constituents, plus balanced nutrients and alkalinity were used to feed the reactor. The ratio of influent to effluent COD was determined at different retention times. The results indicated that the removal efficiency of each selected compound is affected by the detention time. At low phenol and hydroquinone concentration (from 700 to 1000 mg/L maximum removal efficiency (over 80 % was obtained. By further increasing in COD loading rate up to 3000 mg/L, a decrease in COD removal rate was occurred. In the reactor containing pyrogallol in COD of 1500 mg/L, the removal rate decreased to 10 percent because of its toxicity for microorganisms.

  11. X-ray tomography investigations on pebble bed structures

    International Nuclear Information System (INIS)

    Reimann, J.; Rolli, R.; Pieritz, R.A.; Ferrero, C.; Di Michiel, M.

    2007-01-01

    Granular materials (pebbles) are used in present ceramic breeder blankets both for the ceramic breeder material and beryllium. The thermal-mechanical behaviour of these pebble beds strongly depends on the arrangement of the pebbles in the bed, their contacts and contact surfaces with other pebbles and with walls. The influence of these quantities is most pronounced for beryllium pebble beds because of the large thermal conductivity ratio of beryllium to helium gas atmosphere. At present, the data base for the pebble bed thermal conductivity (k) and heat transfer coefficient (h) is quite limited for compressed beds and significant discrepancies exist in respect to h. The detailed knowledge of the pebble bed topology is, therefore, essential to better understand the heat transfer mechanisms. In the present work, results from detailed X-ray tomography investigations are reported on pebble topology in i) the pebble bed bulk (which is relevant for k), and ii) the region close to walls with thicknesses of several pebble diameters (relevant for h). At Forschungszentrum Karlsruhe, pebble beds consisting of aluminium spheres with diameters of 2.3 and 5 mm, respectively, (simulating the blanket relevant 1 mm beryllium pebbles), were uniaxially compressed at different pressure levels. High resolution three-dimensional microtomography (MT) experiments were subsequently performed at the European Synchrotron Radiation Facility, Grenoble. Radial and axial void fraction distributions were found to be oscillatory next to the walls and non-oscillatory in the bulk. For non-compressed pebble beds, the bulk void fraction is fairly constant; for compressed beds, a gradient exists along the compression axis. In the bulk, the angular distribution of pebble contacts was found to be fairly constant, indicating that no regular packing structure is induced. In the wall region, the pebble layer touching the wall is composed of zones with hexagonal structures as shown clearly by MT images. This

  12. Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

    Directory of Open Access Journals (Sweden)

    Jafari Mohammad Javad

    2012-12-01

    Full Text Available Abstract The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p 3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream.

  13. Preliminary Study of 20 MWth Experiment Power Reactor based on Pebble Bed Reactor

    Science.gov (United States)

    Irwanto, Dwi; Permana, Sidik; Pramuditya, Syeilendra

    2017-07-01

    In this study, preliminary design calculations for experimental small power reactor (20 MWt) based on Pebble Bed Reactor (PBR) are performed. PBR technology chosen due to its advantages in neutronic and safety aspects. Several important parameters, such as fissile enrichment, number of fuel passes, burnup and effective multiplication factor are taken into account in the calculation to find neutronic characteristics of the present reactor design.

  14. Researchers solve big mysteries of pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shams, Afaque; Roelofs, Ferry; Komen, E.M.J. [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Baglietto, Emilio [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Nuclear Science and Engineering; Sgro, Titus [CD-adapco, London (United Kingdom). Technical Marketing

    2014-03-15

    The PBR is one type of High Temperature Reactors, which allows high temperature work while preventing the fuel from melting (bringing huge safety margins to the reactor) and high electricity efficiency. The design is also highly scalable; a plant could be designed to be as large or small as needed, and can even be made mobile, allowing it to be used onboard a ship. In a PBR, small particles of nuclear fuel, embedded in a moderating graphite pebble, are dropped into the reactor as needed. At the bottom, the pebbles can be removed simply by opening a small hatch and letting gravity pull them down. To cool the reactor and create electricity, helium gas is pumped through the reactor to pull heat out which is then run through generators. One of the most difficult problems to deal with has been the possible appearance of local temperature hotspots within the pebble bed heating to the point of melting the graphite moderators surrounding the fuel. Obviously, constructing a reactor and experimenting to investigate this possibility is out of the question. Instead, nuclear engineers have been attempting to simulate a PBR with various CFD codes. The thermo-dynamic analysis to simulate realistic conditions in a pebble bed are described and the results are shown. (orig.)

  15. Styrene biofiltration in a trickle-bed reactor

    Directory of Open Access Journals (Sweden)

    V. Novak

    2008-04-01

    Full Text Available The biological treatment of styrene waste gas in a trickle-bed filter (TBF was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC.The main aim of our study was to observe the effect of empty-bed residence time (EBRT on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3. EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC of 11.3 gC.m-3.h-1 was reached at an organic loading (OL rate of 18.6 gC.m-3.h-1.

  16. Semi-dry flue gas desulfurization using Ca(OH)2 in a fluidized bed reactor with bed materials

    International Nuclear Information System (INIS)

    Park, Young Oak; Roh, Hak Jae; Oh, Chang Sup; Kim, Yong Ha

    2010-01-01

    The main objective of present work is to reduce sulfur dioxide emission from power plant for the environment protection. The fluidized bed (FB) was used as the reactor with bed materials in a new semi-dry flue gas desulfurization (FGD) process to achieve high desulfurization efficiency (>98%). Fine powder of Ca(OH) 2 as sorbent and water were continuously fed separately to the bed reactor where bed materials (2 mm glass beads) were fluidized vigorously with flue gas (flow 720 Nm 3 / hr) using bench scale plant of stainless steel column. We have investigated different effects of water injection flow rate, Ca/ S molar ratio and weight of bed materials on SO 2 removal. The increments in the Ca/ S molar ratio and water injection flow rate have been resulted higher desulfurization efficiency with certain disadvantages such as higher sorbent cost and lower temperature of the treated flue gas, respectively. (author)

  17. Advantages of forced non-steady operated trickle-bed reactors

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    2002-01-01

    Trickle-bed reactors are usually operated in the steady state trickle flow regime. Uneven liquid distribution and the formation of hot spots are the most serious problems experienced during trickle flow operation. In this paper, we advocate the use of non-steady state operation of trickle-bed

  18. Heat Transfer in a Fixed Bed of Straw Char

    DEFF Research Database (Denmark)

    Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Jensen, Anker

    2003-01-01

    A model for the thermal conductivity of a straw char bed has been developed. The model extends the work of Yagi and Kunii to describe heat transfer in a bed of cylinders, using a relationship between the interparticle distance and the external porosity. To verify the model, thermal conductivity...... the experimental uncertainty over the range of conditions investigated. The heat transfer model was used in a parametric study to evaluate the effect of gas flow rate, particle diameter, porosity, and temperature on the thermal conductivity in a straw char bed....... experiments were performed on shredded and un-shredded straw char samples, varying particle size, bed packing (loose or dense), and temperature. Predictions with the model, using the measured external porosity and particle diameter as input parameters, are in agreement with measurements within...

  19. A novel auto-thermal reforming membrane reactor for high purity H2

    International Nuclear Information System (INIS)

    Tony Boyd; Grace, J.R.; Lim, C.J.; Adris, A.M.

    2006-01-01

    A novel hydrogen reactor based on steam reforming of natural gas has been developed and tested. The reactor produces high purity hydrogen using in-situ perm-selective membranes installed in a fluidized catalyst bed, thus shifting the thermodynamic equilibrium of the SMR reaction and eliminating the need for downstream hydrogen purification. The reactor is particularly suited to auto-thermal reforming, where air is added to the reformer to provide the endothermic reaction heat, thus eliminating the need to indirectly heat the reactor. The gas flow pattern within the fluidized bed induces an internal circulation of catalyst particles between the central SMR reaction (permeation) zone and an outer annulus. The circulating hot catalyst particles from the oxidation zone carry the required endothermic heat of reaction for the reforming, while ensuring that the palladium membranes are not exposed to excessive temperatures or to oxygen. Another beneficial characteristic of the reactor is that very little of the nitrogen present in the oxidation air reaches the reaction zone, thus maintaining the hydrogen driving force for the perm-selective membranes. Pilot plant results carried out in a semi-industrial scale reactor will be presented. The reactor was operated up to 650 C and 14 bar. Pure hydrogen (99.999+%) was initially obtained from the reactor and an equilibrium shift was demonstrated. (authors)

  20. Field Synergy Analysis and Optimization of the Thermal Behavior of Lithium Ion Battery Packs

    Directory of Open Access Journals (Sweden)

    Hongwen He

    2017-01-01

    Full Text Available In this study, a three dimensional (3D modeling has been built for a lithium ion battery pack using the field synergy principle to obtain a better thermal distribution. In the model, the thermal behavior of the battery pack was studied by reducing the maximum temperature, improving the temperature uniformity and considering the difference between the maximum and maximum temperature of the battery pack. The method is further verified by simulation results based on different environmental temperatures and discharge rates. The thermal behavior model demonstrates that the design and cooling policy of the battery pack is crucial for optimizing the air-outlet patterns of electric vehicle power cabins.

  1. Coil winding pack FE-analysis for a HELIAS reactor

    International Nuclear Information System (INIS)

    Schauer, F.; Egorov, K.; Bykov, V.

    2011-01-01

    At the Max-Planck-Institut fuer Plasmaphysik (IPP) a reference design is being created of an upgraded five-periodic HELIAS type stellarator reactor which evolves from Wendelstein 7-X (W7-X) by scaling of the coil centre line geometries by a factor of four. This reactor type was extensively investigated at IPP with regard to physical characteristics and to some extent also to engineering issues. The upgrade concerns an increase of the induction at the plasma axis and correspondingly at the superconductor. The aim is to develop the reactor concept to a stage and such detail that major engineering problems are unveiled, and relevant comparisons with other concepts, including tokamaks, can be drawn in view of upcoming decisions concerning a DEMO reactor. Even though progress in plasma physics, and in particular future results of W7-X and other machines - particularly of ITER - will probably lead to somewhat different coil shapes, no principal changes of the reference design are expected. In this paper the option of a roll-formed square coil cable jacket is investigated. Detailed structural FE analysis of the coil winding pack demonstrates the feasibility of such a conductor which appears to be the most economical option. It also allows sufficient space for a cable current density very similar to that of the ITER TF coil with a similar overall winding pack cross section of ∼0.5 m 2 . Already existing Nb 3 Sn conductors could thus be safely applied in such a HELIAS reactor. Obvious progress of superconductor technology, particularly concerning Nb 3 Al, will be beneficial concerning savings of conductor material, ease of manufacture, higher operation temperature, etc.

  2. Power generation by packed-bed air-cathode microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan

    2013-08-01

    Catalysts and catalyst binders are significant portions of the cost of microbial fuel cell (MFC) cathodes. Many materials have been tested as aqueous cathodes, but air-cathodes are needed to avoid energy demands for water aeration. Packed-bed air-cathodes were constructed without expensive binders or diffusion layers using four inexpensive carbon-based materials. Cathodes made from activated carbon produced the largest maximum power density of 676±93mW/m2, followed by semi-coke (376±47mW/m2), graphite (122±14mW/m2) and carbon felt (60±43mW/m2). Increasing the mass of activated carbon and semi-coke from 5 to ≥15g significantly reduced power generation because of a reduction in oxygen transfer due to a thicker water layer in the cathode (~3 or ~6cm). These results indicate that a thin packed layer of activated carbon or semi-coke can be used to make inexpensive air-cathodes for MFCs. © 2013 Elsevier Ltd.

  3. Localization of the hot spots in a pebble bed reactor

    International Nuclear Information System (INIS)

    Chen, Leisheng; Lee, Wooram; Lee, Jaeyoung

    2016-01-01

    The pebble bed reactor (PBR) is a candidate reactor type for the very high temperature reactor (VHTR), which is one of the Generation-IV reactor types. The HTGR design concept exhibits excellent safety features due to the low power density and the large amount of graphite present in the core which gives a large thermal inertia in an accident such as loss of coolant. The conclusions are made and may contribute to a better design of a PBR core and a closer inspection of the local hot spots to avoid destruction of pebbles from happening. Thermal field of a PBR core is investigated in this study. Specifically, experiments on measuring the pebbles' surface temperature are performed. It is found that the upper pebble has an overall higher temperature profile than the other pebbles and the stagnation zone under does not increase its surface's temperature. In addition, the temperature profile of the side pebble shows a concave form and it keeps decreasing from the contact point to the vertex in the lower pebble. Lastly, the maximum temperature difference among these points is 5.83 deg. C. These findings above are validated by CFX simulations under two different turbulence models (k-e, SST) and two contact areas (diameter of 6mm and 3.5mm). By contrasting the temperature variation trends of all simulation cases, it is concluded that SST turbulence model with 20% intensity shows a better agreement with the experiment result, nevertheless, slightly deviation is also found in terms of total temperature difference and the peak appears in position 17-19 in experiments

  4. Localization of the hot spots in a pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Leisheng; Lee, Wooram; Lee, Jaeyoung [Handong Global University, Pohang (Korea, Republic of)

    2016-05-15

    The pebble bed reactor (PBR) is a candidate reactor type for the very high temperature reactor (VHTR), which is one of the Generation-IV reactor types. The HTGR design concept exhibits excellent safety features due to the low power density and the large amount of graphite present in the core which gives a large thermal inertia in an accident such as loss of coolant. The conclusions are made and may contribute to a better design of a PBR core and a closer inspection of the local hot spots to avoid destruction of pebbles from happening. Thermal field of a PBR core is investigated in this study. Specifically, experiments on measuring the pebbles' surface temperature are performed. It is found that the upper pebble has an overall higher temperature profile than the other pebbles and the stagnation zone under does not increase its surface's temperature. In addition, the temperature profile of the side pebble shows a concave form and it keeps decreasing from the contact point to the vertex in the lower pebble. Lastly, the maximum temperature difference among these points is 5.83 deg. C. These findings above are validated by CFX simulations under two different turbulence models (k-e, SST) and two contact areas (diameter of 6mm and 3.5mm). By contrasting the temperature variation trends of all simulation cases, it is concluded that SST turbulence model with 20% intensity shows a better agreement with the experiment result, nevertheless, slightly deviation is also found in terms of total temperature difference and the peak appears in position 17-19 in experiments.

  5. X-ray digital industrial radiography (DIR) for local liquid velocity (V{sub LL}) measurement in trickle bed reactors (TBRs): Validation of the technique

    Energy Technology Data Exchange (ETDEWEB)

    Mohd Salleh, Khairul Anuar, E-mail: kmfgf@mst.edu; Lee, Hyoung Koo [Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, Fulton Hall, 310 W. 14th St., Rolla, Missouri 65409 (United States); Rahman, Mohd Fitri Abdul [Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 143 Schrenk Hall, 400 W. 11th St., Rolla, Missouri 65409 (United States); Al Dahhan, Muthanna H. [Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, Fulton Hall, 310 W. 14th St., Rolla, Missouri 65409 (United States); Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, 143 Schrenk Hall, 400 W. 11th St., Rolla, Missouri 65409 (United States)

    2014-06-15

    Local liquid velocity measurements in Trickle Bed Reactors (TBRs) are one of the essential components in its hydrodynamic studies. These measurements are used to effectively determine a reactor's operating condition. This study was conducted to validate a newly developed technique that combines Digital Industrial Radiography (DIR) with Particle Tracking Velocimetry (PTV) to measure the Local Liquid Velocity (V{sub LL}) inside TBRs. Three millimeter-sized Expanded Polystyrene (EPS) beads were used as packing material. Three validation procedures were designed to test the newly developed technique. All procedures and statistical approaches provided strong evidence that the technique can be used to measure the V{sub LL} within TBRs.

  6. Treatment of Ni-EDTA containing wastewater by electrocoagulation using iron scraps packed-bed anode.

    Science.gov (United States)

    Ye, Xiaokun; Zhang, Junya; Zhang, Yan; Lv, Yuancai; Dou, Rongni; Wen, Shulong; Li, Lianghao; Chen, Yuancai; Hu, YongYou

    2016-12-01

    The unique electrocoagulator proposed in this study is highly efficient at removing Ni-EDTA, providing a potential remediation option for wastewater containing lower concentrations of Ni-EDTA (Ni ≤ 10 mg L -1 ). In the electrocoagulation (EC) system, cylindrical graphite was used as a cathode, and a packed-bed formed from iron scraps was used as an anode. The results showed that the removal of Ni-EDTA increased with the application of current and favoured acidic conditions. We also found that the iron scrap packed-bed anode was superior in its treatment ability and specific energy consumption (SECS) compared with the iron rod anode. In addition, the packed density and temperature had a large influence on the energy consumption (ECS). Over 94.3% of Ni and 95.8% of TOC were removed when conducting the EC treatment at an applied current of 0.5 A, initial pH of 3, air-purged rate 0.2 L min -1 , anode packed density of 400 kg m -3 temperature of 313 K and time of 30 min. SEM analysis of the iron scraps indicated that the specific area of the anode increased after the EC. The XRD analysis of flocs produced during EC revealed that hematite (α-Fe 2 O 3 ) and magnetite (Fe 3 O 4 ) were the main by-products under aerobic and anoxic conditions, respectively. A kinetic study demonstrated that the removal of Ni-EDTA followed a first-order model with the current parameters. Moreover, the removal efficiency of real wastewater was essentially consistent with that of synthetic wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Computational fluid dynamic and thermal analysis of Lithium-ion battery pack with air cooling

    International Nuclear Information System (INIS)

    Saw, Lip Huat; Ye, Yonghuang; Tay, Andrew A.O.; Chong, Wen Tong; Kuan, Seng How; Yew, Ming Chian

    2016-01-01

    Highlights: • We designed and analyzed the thermal behavior of the Li-ion battery pack. • We analyzed the heat generation of 38,120 Li-ion cell using ARC. • We validated the simulation results with experimental studies. • We developed the correlations of Nu and Re for the air cooling battery pack. - Abstract: A battery pack is produced by connecting the cells in series and/or in parallel to provide the necessary power for electric vehicles (EVs). Those parameters affecting cost and reliability of the EVs, including cycle life, capacity, durability and warranty are highly dependent on the thermal management system. In this work, computational fluid dynamic analysis is performed to investigate the air cooling system for a 38,120 cell battery pack. The battery pack contained 24 pieces of 38,120 cells, copper bus bars, intake and exhaust plenum and holding plates with venting holes. Heat generated by the cell during charging is measured using an accelerating rate calorimeter. Thermal performances of the battery pack were analyzed with various mass flow rates of cooling air using steady state simulation. The correlation between Nu number and Re number were deduced from the numerical modeling results and compared with literature. Additionally, an experimental testing of the battery pack at different charging rates is conducted to validate the correlation. This method provides a simple way to estimate thermal performance of the battery pack when the battery pack is large and full transient simulation is not viable.

  8. Passive cooling of a fixed bed nuclear reactor

    International Nuclear Information System (INIS)

    Petry, V.J.; Bortoli, A.L. de; Sefidwash, F.

    2005-01-01

    Small nuclear reactors without the need for on-site refuelling have greater simplicity, better compliance with passive safety systems, and are more adequate for countries with small electric grids and limited investment capabilities. Here the passive cooling characteristic of the fixed bed nuclear reactor (FBNR), that is being developed under the International Atomic Energy Agency (IAEA) Coordinated Research Project, is studied. A mathematical model is developed to calculate the temperature distribution in the fuel chamber of the reactor. The results demonstrate the passive cooling of this nuclear reactor concept. (authors)

  9. Hydrogen isotopic exchange reaction in a trickle-bed

    International Nuclear Information System (INIS)

    Paek, Seung Woo; Ahn, Do Hee; Kim, Kwang Rag; Lee, Min Soo; Yim, Sung Paal; Chung, Hong Suk

    2005-01-01

    The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is ideally suited for extracting tritium from water because of its high separation factor and mild operating conditions. This process for different hydrogen isotope applications has been developed by AECL. A laboratory scale CECE was built and operated at Mound Laboratory. Belgium and Japan have also developed independently similar processes which are based on a hydrophobic catalyst. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. The liquid phase catalytic exchange columns having various structures were developed; and it has been recognized that a multistage type and a trickle-bed type are promising. The multistage type gave more successful results than the trickle-bed type. However, the structure of the column is complicated. The trickle-bed type has a significant advantage in that the structure of the column is quite simple: the hydrophobic catalysts or the catalysts and packings are packed within the column. This structure would lead us to a smaller column height than the multistage type. This paper deals with the experiment for the hydrogen isotope exchange in a trickle-bed reactor packed with a hydrophobic catalyst and the design of the catalytic column for the CECE to tritium recovery from light water

  10. Hydrogen isotopic exchange reaction in a trickle-bed

    Energy Technology Data Exchange (ETDEWEB)

    Paek, Seung Woo; Ahn, Do Hee; Kim, Kwang Rag; Lee, Min Soo; Yim, Sung Paal; Chung, Hong Suk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2005-07-01

    The CECE (Combined Electrolysis Catalytic Exchange) with a hydrophobic catalyst is ideally suited for extracting tritium from water because of its high separation factor and mild operating conditions. This process for different hydrogen isotope applications has been developed by AECL. A laboratory scale CECE was built and operated at Mound Laboratory. Belgium and Japan have also developed independently similar processes which are based on a hydrophobic catalyst. The CECE column is composed of an electrolysis cell and a liquid phase catalytic exchange column. The liquid phase catalytic exchange columns having various structures were developed; and it has been recognized that a multistage type and a trickle-bed type are promising. The multistage type gave more successful results than the trickle-bed type. However, the structure of the column is complicated. The trickle-bed type has a significant advantage in that the structure of the column is quite simple: the hydrophobic catalysts or the catalysts and packings are packed within the column. This structure would lead us to a smaller column height than the multistage type. This paper deals with the experiment for the hydrogen isotope exchange in a trickle-bed reactor packed with a hydrophobic catalyst and the design of the catalytic column for the CECE to tritium recovery from light water.

  11. Biodenitrification of gaseous diffusion plant aqueous wastes: stirred bed reactor

    International Nuclear Information System (INIS)

    Holland, M.E.

    1980-01-01

    Approximately 30 kilograms of nitrates per day are discarded in the raffinates (acid wastes) of the Portsmouth Gaseous Diffusion Plant's X-705 Uranium Recovery and Decontamination Facility. A biodenitrification process employing continuous-flow, stirred-bed reactors has been successfully used to remove nitrates from similar acid wastes at the Oak Ridge Y-12 Plant. Laboratory studies have been made at Portsmouth to characterize the X-705 raffinates and to test the stirred-bed biodenitrification process on such raffinates. Raffinates which had been previously characterized were pumped through continuous-flow, stirred-bed, laboratory-scale reactors. Tests were conducted over a period of 146 days and involved variations in composition, mixing requirements, and the fate of several metal ions in the raffinates. Tests results show that 20 weight percent nitrates were reduced to a target nitrate effluent concentration of 100 μg/ml with a 99.64 percent efficiency. However, the average denitrification rate achieved was only 33% of that demonstrated with the Y-12 stirred-bed system. These low rates were probably due to the toxic effects of heavy metal ions on the denitrifying bacteria. Also, most of the uranium in the raffinate feed remained in the biomass and calcite, which collected in the reactor. This could cause criticality problems. For these reasons, it was decided not to make use of the stirred-bed bioreactor at Portsmouth. Instead, the biodenitrification installation now planned will use fluidized bed columns whose performance will be the subject of a subsequent report

  12. Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

    Science.gov (United States)

    Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

    2018-02-01

    In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

  13. What can recycling in thermal reactors accomplish?

    International Nuclear Information System (INIS)

    Piet, Steven J.; Matthern, Gretchen E.; Jacobson, Jacob J.

    2007-01-01

    Thermal recycle provides several potential benefits when used as stop-gap, mixed, or backup recycling to recycling in fast reactors. These three roles involve a mixture of thermal and fast recycling; fast reactors are required to some degree at some time. Stop-gap uses thermal reactors only until fast reactors are adequately deployed and until any thermal-recycle-only facilities have met their economic lifetime. Mixed uses thermal and fast reactors symbiotically for an extended period of time. Backup uses thermal reactors only if problems later develop in the fast reactor portion of a recycling system. Thermal recycle can also provide benefits when used as pure thermal recycling, with no intention to use fast reactors. However, long term, the pure thermal recycling approach is inadequate to meet several objectives. (authors)

  14. What can Recycling in Thermal Reactors Accomplish?

    International Nuclear Information System (INIS)

    Steven Piet; Gretchen E. Matthern; Jacob J. Jacobson

    2007-01-01

    Thermal recycle provides several potential benefits when used as stop-gap, mixed, or backup recycling to recycling in fast reactors. These three roles involve a mixture of thermal and fast recycling; fast reactors are required to some degree at some time. Stop-gap uses thermal reactors only until fast reactors are adequately deployed and until any thermal-recycle-only facilities have met their economic lifetime. Mixed uses thermal and fast reactors symbiotically for an extended period of time. Backup uses thermal reactors only if problems later develop in the fast reactor portion of a recycling system. Thermal recycle can also provide benefits when used as pure thermal recycling, with no intention to use fast reactors. However, long term, the pure thermal recycling approach is inadequate to meet several objectives

  15. Complex nonlinear behaviour of a fixed bed reactor with reactant recycle

    DEFF Research Database (Denmark)

    Recke, Bodil; Jørgensen, Sten Bay

    1999-01-01

    The fixed bed reactor with reactant recycle investigated in this paper can exhibit periodic solutions. These solutions bifurcate from the steady state in a Hopf bifurcation. The Hopf bifurcation encountered at the lowest value of the inlet concentration turns the steady state unstable and marks......,that the dynamic behaviour of a fixed bed reactor with reactant recycle is much more complex than previously reported....

  16. Understanding the performance of sulfate reducing bacteria based packed bed reactor by growth kinetics study and microbial profiling.

    Science.gov (United States)

    Dev, Subhabrata; Roy, Shantonu; Bhattacharya, Jayanta

    2016-07-15

    A novel marine waste extract (MWE) as alternative nitrogen source was explored for the growth of sulfate reducing bacteria (SRB). Variation of sulfate and nitrogen (MWE) showed that SRB growth follows an uncompetitive inhibition model. The maximum specific growth rates (μmax) of 0.085 and 0.124 h(-1) and inhibition constants (Ki) of 56 and 4.6 g/L were observed under optimized sulfate and MWE concentrations, respectively. The kinetic data shows that MWE improves the microbial growth by 27%. The packed bed bioreactor (PBR) under optimized sulfate and MWE regime showed sulfate removal efficiency of 62-66% and metals removal efficiency of 66-75% on using mine wastewater. The microbial community analysis using DGGE showed dominance of SRB (87-89%). The study indicated the optimum dosing of sulfate and cheap organic nitrogen to promote the growth of SRB over other bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Methanol steam-reforming in a catalytic fixed bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Duesterwald, H G; Hoehlein, B; Kraut, H; Meusinger, J; Peters, R [Research Centre Juelich (KFA) (Germany). Inst. of Energy Process Engineering; Stimming, U [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Festkoerperphysik und Techn. Phys.

    1997-12-01

    Designing an appropriate methanol steam reformer requires detailed knowledge about the processes within such a reactor. Thus, the axial temperature and concentration gradients and catalyst ageing were investigated. It was found that for a fresh catalyst load, the catalyst located in the reactor entrance was most active during the experiment. The activity of this part of the catalyst bed decreased after some time of operation due to ageing. With further operation, the most active zone moved through the catalyst bed. From the results concerning hydrogen production and catalyst degradation, the necessary amount of catalyst for a mobile PEMFC-system can be estimated. (orig.)

  18. Engineering design of a direct-cycle steam-generating blanket for a long-pulse fusion reactor

    International Nuclear Information System (INIS)

    Cort, G.E.; Hagenson, R.L.; Teasdale, R.W.; Fox, W.E.; Soran, P.D.; Cullingford, H.S.; Bathke, C.G.; Krakowski, R.A.

    1979-01-01

    A comprehensive neutronics, thermohydraulic, and mechanical design of a tritium-breeding blanket for use by a conceptual long-pulse Reversed-Field Pinch Reactor (RFPR) is described. On the basis of constraints imposed by cost and the desire to use existing technology, a direct-cycle steam system and stainless-steel construction were used. For reasons of plasma stability, the RFPR blanket supports a 20-mm-thick copper first wall. Located behind the 1.5-m-radius first wall is a 0.50-m-thick stainless-steel blanket containing a granular bed of Li 2 O through which flows low-pressure helium (0.1 MPa) for tritium extraction. Water/steam tubes radially penetrate this packed bed. The large thermal capacity and low thermal diffusivity of the Li 2 O blanket are sufficient to maintain a nearly constant temperature during the approx. 25-s burn period

  19. Pre-combustion capture of carbon dioxide in a fixed bed reactor using the clathrate hydrate process

    International Nuclear Information System (INIS)

    Babu, Ponnivalavan; Kumar, Rajnish; Linga, Praveen

    2013-01-01

    Hydrate based gas separation (HBGS) process with silica sand and silica gel as contact medium was employed to capture CO 2 from fuel gas mixture. Gas uptake measurement at three different pressures (7.5, 8.5 and 9.0 MPa) and 274.15 K were conducted for hydrate formation kinetics and overall conversion of water to hydrate, rate of hydrate formation were determined. Water conversion of up to 36% was achieved with silica sand bed compared to 13% conversion in the silica gel bed. Effect of driving force on the rate of hydrate formation and gas consumption was significant in silica sand bed whereas it was found to be insignificant in silica gel bed. Hydrate dissociation experiments by thermal stimulation (at constant pressure) alone and a combination of depressurization and thermal stimulation were carried out for complete recovery of the hydrated gas. A driving force of 23 K was found to be sufficient to recover all the hydrated gas within 1 h. This study indicates that silica sand can be an effective porous media for separation of CO 2 from fuel gas when compared to silica gel. - Highlights: ► The clathrate process for pre-combustion capture of carbon dioxide in a novel fixed bed reactor is presented. ► Performance of two contact media (silica gel and silica sand) was investigated. ► Water to hydrate conversion was higher in a silica sand column. ► A pressure reduction and thermal stimulation approach is presented for a complete recovery of the hydrated gas

  20. Simulation in CFD of a Pebble Bed: Advanced high temperature reactor core using OpenFOAM

    International Nuclear Information System (INIS)

    Dahl, Pamela M.; Su, Jian

    2017-01-01

    Numerical simulations of a Pebble Bed nuclear reactor core are presented using the multi-physics tool-kit OpenFOAM. The HTR-PM is modeled using the porous media approach, accounting both for viscous and inertial effects through the Darcy and Forchheimer model. Initially, cylindrical 2