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Qingshan Huang - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamics and mass transfer in a slurry external airlift Loop Reactor integrating mixing and separation
Chemical Engineering Science, 2020Co-Authors: Shujun Geng, Fei Gao, Hongyan Liu, Chao Yang, Qingshan HuangAbstract:Abstract A pilot external airlift Loop Reactor (EALR) integrating mixing and separation was first proposed by combining directional flow in the EALR and liquid-solid separation in two parallel hydrocyclones. In this developed Reactor, mixing, mass transfer, and liquid-solid separation can be simultaneously realized without extra energy input. Technical feasibility was firstly verified, and then hydrodynamics and mass transfer were measured. It was found that the minimum diameter of solid particles retained for circulation was 6.82 μm, and the treatment capacity of clean liquid was up to 3.0 m3/h. Additionally, global gas holdup, liquid circulating velocity, and volumetric mass transfer coefficient increased monotonously with increasing the superficial gas velocity while declined with the increase of solid concentration. Axial inhomogeneity of solid particles was decayed with increasing the superficial gas velocity and solid concentration. This new type of slurry EALR is promising to be applied in the gas-liquid-solid catalytic industries.
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Experimental investigation of hydrodynamics and mass transfer in a slurry multistage internal airlift Loop Reactor
Chemical Engineering Journal, 2020Co-Authors: Jinliang Tao, Jiangang Huang, Shujun Geng, Fei Gao, Qingshan HuangAbstract:Abstract Hydrodynamics and mass transfer of gas-liquid-solid slurry flow in a simple pilot multistage internal airlift Loop Reactor with a classic stage clearance are investigated experimentally. The presence of a critical superficial gas velocity to keep the multistage internal airlift Loop Reactor operating normally without particle deposit was first observed at a certain solid concentration and a fixed height of stage clearance, and an empirical model related to solid concentrations for a constant stage gap is also put forward here to predict the minimum critical superficial gas velocity in the slurry multistage internal airlift Loop Reactor. The results showed that compared to hydrodynamics and mass transfer in the gas-liquid two-phase flow at the same conditions, the solid concentration and the superficial gas velocity have some distinct effects. The increment of superficial gas velocity can increase the gas holdup, circulating liquid velocity, and volumetric mass transfer coefficient and at the same time decrease the mixing time, while the addition of solid particles would get the opposite effects. Additionally, compared to the two-phase flow, reverse tendencies of the gas holdup and circulating liquid velocity in different stages in the three-phase slurry multistage internal airlift Loop Reactor are first observed due to axial non-uniform distribution of solid particles. Therefore, solid particles can change the nature of multiphase flow in the multistage internal airlift Loop Reactor, and some critical information for designing this type of Reactor was provided in this work.
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modeling transport phenomena and reactions in a pilot slurry airlift Loop Reactor for direct coal liquefaction
Chemical Engineering Science, 2015Co-Authors: Qingshan Huang, Weipeng Zhang, Chao YangAbstract:Modeling of hydrodynamics, mass/heat transfer and chemical reactions with bubbly flow in a pilot slurry internal airlift Loop Reactor (IALR) for the process of direct coal liquefaction (DCL) under the conditions of elevated pressure and high temperature is performed with a steady two fluid model. A modified numerical method for multiphase flow and the developed boundary conditions to promote the convergence of steady solutions are also proposed. The results show that the predicted average gas voidage, average liquid velocity and temperature at two locations in the riser agree reasonably well with experimental data. The snapshots of temperature and concentrations of the reactants in respective phases and the product in slurry are all well captured. The models and numerical procedure developed in this work can be used as an effective tool for design and scale-up of IALRs for the DCL process. (C) 2015 Elsevier Ltd. All rights reserved.
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cfd simulation of hydrodynamics and mass transfer in an internal airlift Loop Reactor using a steady two fluid model
Chemical Engineering Science, 2010Co-Authors: Qingshan Huang, Chao Yang, Gengzhi YuAbstract:Steady state simulation of the hydrodynamics and mass transfer in bubbly flow in an axisymmetric internal airlift Loop Reactor (IALR) with the special treatment of interphase decoupling and outlet boundary conditions is performed, which is based on a Favre averaging two-fluid model for multiphase flow. Different models of mass transfer coefficient are compared and validated with the literature data. A model for describing the mass transfer for a wide range of superficial gas velocity is chosen and the predicted mass transfer coefficient agrees well with the experimental data in the literature. The numerical procedure can be used as a tool for the design and scale-up of IALRs. (C) 2010 Elsevier Ltd. All rights reserved.
Chao Yang - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamics and mass transfer in a slurry external airlift Loop Reactor integrating mixing and separation
Chemical Engineering Science, 2020Co-Authors: Shujun Geng, Fei Gao, Hongyan Liu, Chao Yang, Qingshan HuangAbstract:Abstract A pilot external airlift Loop Reactor (EALR) integrating mixing and separation was first proposed by combining directional flow in the EALR and liquid-solid separation in two parallel hydrocyclones. In this developed Reactor, mixing, mass transfer, and liquid-solid separation can be simultaneously realized without extra energy input. Technical feasibility was firstly verified, and then hydrodynamics and mass transfer were measured. It was found that the minimum diameter of solid particles retained for circulation was 6.82 μm, and the treatment capacity of clean liquid was up to 3.0 m3/h. Additionally, global gas holdup, liquid circulating velocity, and volumetric mass transfer coefficient increased monotonously with increasing the superficial gas velocity while declined with the increase of solid concentration. Axial inhomogeneity of solid particles was decayed with increasing the superficial gas velocity and solid concentration. This new type of slurry EALR is promising to be applied in the gas-liquid-solid catalytic industries.
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modeling transport phenomena and reactions in a pilot slurry airlift Loop Reactor for direct coal liquefaction
Chemical Engineering Science, 2015Co-Authors: Qingshan Huang, Weipeng Zhang, Chao YangAbstract:Modeling of hydrodynamics, mass/heat transfer and chemical reactions with bubbly flow in a pilot slurry internal airlift Loop Reactor (IALR) for the process of direct coal liquefaction (DCL) under the conditions of elevated pressure and high temperature is performed with a steady two fluid model. A modified numerical method for multiphase flow and the developed boundary conditions to promote the convergence of steady solutions are also proposed. The results show that the predicted average gas voidage, average liquid velocity and temperature at two locations in the riser agree reasonably well with experimental data. The snapshots of temperature and concentrations of the reactants in respective phases and the product in slurry are all well captured. The models and numerical procedure developed in this work can be used as an effective tool for design and scale-up of IALRs for the DCL process. (C) 2015 Elsevier Ltd. All rights reserved.
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cfd simulation of hydrodynamics and mass transfer in an internal airlift Loop Reactor using a steady two fluid model
Chemical Engineering Science, 2010Co-Authors: Qingshan Huang, Chao Yang, Gengzhi YuAbstract:Steady state simulation of the hydrodynamics and mass transfer in bubbly flow in an axisymmetric internal airlift Loop Reactor (IALR) with the special treatment of interphase decoupling and outlet boundary conditions is performed, which is based on a Favre averaging two-fluid model for multiphase flow. Different models of mass transfer coefficient are compared and validated with the literature data. A model for describing the mass transfer for a wide range of superficial gas velocity is chosen and the predicted mass transfer coefficient agrees well with the experimental data in the literature. The numerical procedure can be used as a tool for the design and scale-up of IALRs. (C) 2010 Elsevier Ltd. All rights reserved.
Michiel T. Kreutzer - One of the best experts on this subject based on the ideXlab platform.
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is a monolithic Loop Reactor a viable option for fischer tropsch synthesis
Chemical Engineering Science, 2003Co-Authors: Ronald M De Deugd, Michiel T. Kreutzer, Freek Kapteijn, Rahul B Chougule, Michiel F Meeuse, Johan Grievink, J A MoulijnAbstract:A Monolithic Loop Reactor design for Fischer-Tropsch synthesis with a production capacity of 5000 ton middle distillates per day (about 40000 bbl/day) is presented. The required volume, 3350 m 3 , is competitive with conventional Reactors, while eliminating disadvantages of existing Reactor types such as catalyst attrition and separation, backmixing and large diffusion distances. Although the kinetic expressions used in this study do not allow calculating the selectivity precisely, all important conditions, low temperature rise and constant H 2 /CO ratios, are met to ensure high selectivity towards heavy hydrocarbons.
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hydrodynamic aspects of the monolith Loop Reactor
Chemical Engineering Science, 2001Co-Authors: Johan J Heiszwolf, Michiel T. Kreutzer, Leon B Engelvaart, Menno G Van Den Eijnden, Freek Kapteijn, J A MoulijnAbstract:Abstract In this paper, the so-called monolith Loop Reactor is introduced. In this Reactor, liquid is circulated over a monolith catalyst using a pump while gas-phase circulation is obtained by the pressure difference across the Reactor. A model is derived to calculate the liquid hold-up inside the monolith as a function of the liquid circulation flow rate. Gas–liquid mass-transfer measurements in a monolith are compared to a model for capillaries. A combination of the hydrodynamic and the mass transfer models leads to predicted kLa values as a function of the power input. The performance of the monolith Loop Reactor is compared to bubble columns and stirred-tank Reactors.
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A dynamic model for the Venturi Loop Reactor Venturi Loop Reactor
Scientific Computing in Chemical Engineering II, 1999Co-Authors: Robbert De Graaf, Remco Reinstra, Maurits Wieberdink, Michiel T. KreutzerAbstract:A dynamic model of a venturi Loop Reactor was set-up. First steady state calculations describing the hydrodynamics and mass transfers coefficients were performed. The second group of simulations concentrated on the performance of the system for different kinetics and operating conditions. Finally the scale up of the Reactor was modelled resulting in the conclusion that using proper chosen scaling rules, the reaction time and time dependency of the key variables can be kept uniform.
Johannes Tramper - One of the best experts on this subject based on the ideXlab platform.
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Liquid/solid mass transfer in an air-lift Loop Reactor with a dispersed solid phase
Journal of Chemical Technology & Biotechnology, 1998Co-Authors: René H. Wijffels, Marleen Verheul, Wim A. Beverloo, Johannes TramperAbstract:In processes with immobilized cells mass transfer across the boundary layer surrounding the support often plays an important role. Relatively little is known about external mass transfer as a function of the superficial gas velocity in bioReactors such as air-lift Loop Reactors. In this work ion-exchange resins were used as a solid phase to determine the mass-transfer coefficient in such a Reactor. Relations between the Sherwood number and the superficial gas velocity were derived and compared with relations from the literature. Relations in which the Sherwood number is a function of the energy-dissipation rate and relations in which the relative particle velocity is calculated from the rate of free fall of the particle were compared. It was shown that the Sherwood numbers that were functions of the energy-dissipation rates were higher than could be calculated on the basis of the rate of free fall. The Sherwood number obtained was used to calculate the kl,s of carrageenan gel beads as a solid phase in an air-lift Loop Reactor. © 1998 SCI.
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Oxygen transfer in a multiple air-lift Loop Reactor
Bioprocess Engineering, 1995Co-Authors: Wilfried A.m. Bakker, Johannes Tramper, M. Hertog, C.d. De GooijerAbstract:The Multiple Air-lift Loop Reactor (MAL) is a new type of bioReactor, in which a series of airlifts with internal Loops is incorporated into one vessel. As such, the MAL is an approximation of an aerated plug-flow fermenter. Gas/liquid oxygen transfer was studied as a function of the gas flow rate in a MAL. The second MAL-compartment in the series was investigated in particular, and a Rectangular Air-lift Loop Reactor (RAL) was used as a reference. Both a dynamic and a steady-state method were used for the determination of the overall volumetric oxygen-transfer coefficient. Both methods gave the same results. The oxygen transfer coefficient in the second MAL-compartment was low compared to that of conventional internal-Loop Reactors. Wall effects probably caused bubble coalescence and a reduction in the oxygen transfer. For the RAL it was found that oxygen transfer was comparable to that in a bubble column.
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Tetralin and oxygen transfer in the liquid-impelled Loop Reactor
Bioprocess Engineering, 1994Co-Authors: M. Vermuë, M. Tacken, Johannes TramperAbstract:During the bioconversion of tetralin in the liquid-impelled Loop Reactor, oxygen and tetralin are transferred from the organic-solvent phase to the aqueous phase. Mass transfer of either tetralin or oxygen is likely to be the rate-limiting step in this bioconversion. In order to establish which of the two is limiting, the overall mass-transfer coefficients (K i,L A) of both substrates were determined. Theoretical calculations did not reveal large differences. Therefore both K i,L A's were experimentally determined as well. From the results it is concluded that neither tetralin nor oxygen can be assigned to be the mass-transfer-limiting factor if tetralin is completely converted into CO2 and H2O. On the other hand, if tetralin is oxidized only partly (the aim of our synthetic studies), it very likely is the limiting substrate and process control can thus be achieved by controlling the supply of this toxic compound.
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Hydrodynamics and mixing in a multiple air-lift Loop Reactor.
Biotechnology and bioengineering, 1993Co-Authors: Wilfried A.m. Bakker, Johannes Tramper, H. J. L. Van Can, C.d. De GooijerAbstract:A new bioReactor, in which a series of air-lift Reactors with an internal Loop is incorporated into one vessel, is introduced. With this multiple air-lift Loop Reactor (MAL) and approximation of an aerated plug-flow fermentor is strived for. Mixing, liquid velocity, and gas hold-up were measured as a function of the gas flow rate in this new internal-Loop Reactor geometry. As a reference, hydrodynamics were also investigated in a conventional internal-Loop Reactor. A model description of the hydrodynamics in the second compartment of the MAL is given. This model is based on a two-phase, drift-flux model and a friction coefficient. Frictional losses were independent of the Reactor bottom geometry, and were observed to increase with the gas flow rate as a result of the presence of stationary gas bubbles in the downcomer. The hydrodynamics and mixing of the second MAL compartment were comparable with those of conventional internal-Loop Reactors.
Karl Schügerl - One of the best experts on this subject based on the ideXlab platform.
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On line measurement and control of penicillin v production in a tower Loop Reactor
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: Th. Lorenz, J. Niehoff, J. Diekmann, K. Frueh, R. Hiddessen, J. Moeller, Karl SchügerlAbstract:Penicillin V was produced in a 98-dm3 tower Loop Reactor using a production strain of Penicillium chrysogenum in pellet form. By using control devices, the aeration, the only energy input in a tower Loop Reactor, decreased by an average of 75%. The amounts of precursor substance (phenoxyacetic acid), acid, base, ammonium sulfate and urea, added during the penicillin fermentation process, were reduced by applying an automatic analysing system to the process.
