Showing papers on "Packed bed published in 1995"
TL;DR: In this paper, a model for the propagation of a localized resonance wave and the superadiabatic reaction effect in a porous medium has been proposed, which is confirmed by experiments and the results of a simple mathematical analysis.
168 citations
Book•
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31 Dec 1995
TL;DR: In this paper, the authors put Packed Column Supercritical Fluid Chromatography into Perspective and discussed the effect of instrumental parameters on Retention, Selectivity, and Efficiency concepts that simplify phase selection.
Abstract: Putting Packed Column Supercritical Fluid Chromatography into Perspective Practical Aspects of SFC Hardware Physical Chemistry of Mobile Phases Used in Packed Column SFC Physical Chemistry of the Stationary Phase The Effect of Instrumental Parameters on Retention, Selectivity, and Efficiency Concepts That Simplify Phase Selection Systematic Method Development Pharmaceutical Analysis by Packed Column SFC Chiral Analysis of Drugs Separation of Agricultural Chemicals by Packed Column SFC SFC and the Petroleum Industry Miscellaneous Applications of Packed Column SFC Subject Index.
139 citations
TL;DR: In this paper, the authors conducted a series of basic experiments for CO2 removal from the flue gas of thermal power plants by use of hollow-fiber gas-liquid contactors.
136 citations
TL;DR: In this article, a semi-empirical relation was proposed to measure the mean particle size, spread of the particle size distribution, particle density, and particle shape of loosely packed and tapped beds.
81 citations
TL;DR: In this paper, a reproducible procedure for packing small-diameter packed beds with a mature of fines and catalyst is reported, which is essential for process catalyst testing in trickle-flow reactors.
Abstract: A reproducible procedure for packing small-diameter packed beds with a mature of fines and catalyst is reported. Such beds are essential for process catalyst testing in trickle-flow reactors. Packing uniformity along the bed, reproducibility of single-phase pressure drop and reproducibility of liquid holdup and two-phase flow pressure drop in repacked beds has been demonstrated
74 citations
Journal Article•
TL;DR: The data presented on the performance of STREAMLINE adsorbents show that they are very useful for recovery of proteins from particle-containing feedstocks using expanded bed adsorption.
Abstract: We have analysed some operational parameters for two novel adsorbents intended for recovery of proteins from particle-containing feedstocks using expanded bed adsorption. The adsorbents tested were STREAMLINE DEAE and STREAMLINE SP, ion exchangers based on an agarose/crystalline quartz composite. Parameters analysed included bed expansion, adsorption efficiency, washing and elution. Bed expansion was considerably lower for STREAMLINE adsorbents compared to conventional agarose based media, higher flow velocities were thus possible during the expanded bed process. Breakthrough capacity was 63 mg ml-1 for lysozyme on STREAMLINE SP and 36 mg ml-1 for bovine serum albumin on STREAMLINE DEAE at a flow velocity of 300 cm h-1. To achieve high breakthrough capacity, the sedimented bed height should be at least 10 cm. Furthermore, breakthrough capacity increased to some extent when temperature was increased from room temperature to 36 degrees C, a phenomenon which can be useful in some processes. The number of living E. coli cells in the effluent was reduced by a factor of 10(5) after washing with 15 sedimented bed volumes. The optimal flow velocity for elution was 100 cm h-1 considering time for elution and volume of the eluted fraction. Flow direction during elution in packed bed mode had little impact on the elution volume, however, elution in expanded bed mode increased the volume by approx. 40%. The data presented on the performance of STREAMLINE adsorbents show that they are very useful for recovery of proteins from particle-containing feedstocks using expanded bed adsorption.
72 citations
TL;DR: Cost analysis indicated that, with heat recovery to reduce heating and cooling costs, the continuous fermentor/stripper is possibly a lower‐cost alternative to conventional fermentation and distillation.
Abstract: Recycling the contents of a continuous fermentor through a stripping column is proposed as a means of reducing product inhibition and lowering the cost of fuel ethanol production. A 2-L fermentor and 10-cm packed column were continuously operated for 150 days without contamination. Some fouling of the packing with attached yeast cells was observed which partially blocked the column. Cell yield was lower than in a simple continuous fermentor. Complete conversion of 200 g/L glucose feed and 90% conversion of 600 g/L glucose feed were achieved. Data were analyzed by computerized process simulation. Cost analysis indicated that, with heat recovery to reduce heating and cooling costs, the continuous fermentor/stripper is possibly a lower-cost alternative to conventional fermentation and distillation.
72 citations
TL;DR: In this paper, a hydrodynamic model based on film flow on the particle scale accommodates both laminar and turbulent films in the entry and developed regime was used for experimental determination of liquid holdup and estimation of the degree of anisotropic liquid distribution.
Abstract: Possibilities of predicting liquid holdup in rotating packed beds are examined using the film flow theory. A hydrodynamic model based on film flow on the particle scale accommodates both laminar and turbulent films in the entry and developed regime. Conductance measurement was used for experimental determination of liquid holdup and estimation of the degree of anisotropy of liquid distribution. Experimental results represent the first data for liquid holdup in the rotating packed bed as a function of operating conditions and liquid properties. They indicate an anisotropic liquid distribution dependent on the operating variables. While the film model can be fitted to the experimental data, such a fit lacks a theoretical basis and the classical theory of film flow on the particle scale cannot explain the liquid flow in rotating packed beds. An empirical expression correlates well the holdup data with the operating parameters.
67 citations
TL;DR: In this article, a mathematical model is developed to simulate oxygen consumption, heat generation and cell growth in solid state fermentation (SSF), where fungal growth on the solid substrate particles results in the increase of the cell film thickness around the particles, leading to decrease in the porosity of the substrate bed and diffusivity of oxygen in the bed.
Abstract: A mathematical model is developed to simulate oxygen consumption, heat generation and cell growth in solid state fermentation (SSF). The fungal growth on the solid substrate particles results in the increase of the cell film thickness around the particles. The model incorporates this increase in the biofilm size which leads to decrease in the porosity of the substrate bed and diffusivity of oxygen in the bed. The model also takes into account the effect of steric hindrance limitations in SSF. The growth of cells around single particle and resulting expansion of biofilm around the particle is analyzed for simplified zero and first order oxygen consumption kinetics. Under conditions of zero order kinetics, the model predicts upper limit on cell density. The model simulations for packed bed of solid particles in tray bioreactor show distinct limitations on growth due to simultaneous heat and mass transport phenomena accompanying solid state fermentation process. The extent of limitation due to heat and/or mass transport phenomena is analyzed during different stages of fermentation. It is expected that the model will lead to better understanding of the transport processes in SSF, and therefore, will assist in optimal design of bioreactors for SSF.
60 citations
TL;DR: In this article, a new model was proposed which makes it possible to estimate the packing surface that actually takes part in the process of absorption of 1,1,1-trichloroethane using Genosorb 300, a mixture of polyethylene glycol dimethyl ethers.
Abstract: In this work a Sulzer structured packing, Mellapak 250Y, was studied for applications in the field of absorption A new model was proposed which makes it possible to estimate the packing surface that actually takes part in the process In the course of these studies, new experimental data were obtained relating to the absorption of 1,1,1-trichloroethane using Genosorb 300, a mixture of polyethylene glycol dimethyl ethers produced by Hoechst SpA, as absorption liquid The results obtained with the proposed model are in agreement both with the experimental measurements made in the course of the work and with experimental absorption measurements reported by other authors on water systems
57 citations
TL;DR: In this paper, a packed bed absorber-stripper system was used to remove selected indoor pollutants during the dehumidification of air by triethylene glycol solutions, and both random and structured packings were employed to provide the contact surface between the liquid and gas phases.
Abstract: A packed bed absorber-stripper system was used to remove selected indoor pollutants during the dehumidification of air by triethylene glycol solutions. Triethylene glycol concentrations of 90% and 95% by weight in water were used. Both random and structured packings were employed to provide the contact surface between the liquid and gas phases. A six-inch I. D. absorption column was operated between 50% and 80% of flooding conditions. The heights of a transfer unit for mass transfer for randomly packed 5/8-inch polypropylene Flexi rings and 1/2-inch ceramic Intalox saddles varied from 0.12 m to 0.17 m when dehumidifying air only. However, the height of a transfer unit was in the range of 0.31 m to 0.40 m for the cross corrugated cellulose and PVC structured packings. Heat and mass transfer coefficients were also calculated from the experimental data and were correlated with various process variables. The values predicted by these correlations were within ±10% of the experimental data. Pollutants ...
TL;DR: In this paper, the authors measured the pH distribution in a carrier-packed biological deodorization (CPBD) reactor which is currently being used in a sewage treatment plant and found that more than 99% of the H2S and 70-80% of MT were removed from the eaw gas in the early section of the packed bed, which comprised one quarter of the total volume of the CPBD reactor.
TL;DR: In this paper, a dynamic two-dimensional modeling was used in a theoretical analysis of the overheating problem in solid-state fermentation within a packed-bed bioreactor, and the model predicted that convection was the dominant heat transfer mechanism under the design and operational parameters applied.
Abstract: Dynamic two-dimensional modelling was used in a theoretical analysis of the overheating problem in solid-state fermentation within a packed-bed bioreactor. The model described the growth and death of the fungus Rhizopus oligosporus as functions of temperature ; the generation of metabolic heat ; and the transfer of heat within the packed-bed by conduction and convection. The model predicted that convection was the dominant heat transfer mechanism under the design and operational parameters applied. Significant death occurred in the upper region of the bed where the highest temperatures were reached. The temperature rise at the top of the bed could be minimised by using high superficial air velocities or low inlet air temperatures. The most effective strategy for a column with a bed height : bed diameter ratio of 1 :1 or less was to use a high superficial air velocity.
TL;DR: In this article, the use of semipermeable nonporous silicone capillary membranes to transfer ozone nondispersively into an aqueous phase and ozonate organic species has been studied for the single pollutants phenol, nitrobenzene and acrylonitrile.
TL;DR: In this paper, visual, video, pressure, and conductance techniques were used to study time-varying disturbances in cocurrent flow in packed beds with vertical and horizontal columns, and it was found that the trickle-pulse transition corresponds to conditions where traveling disturbances finaly become measurable, not the conditions at which infinitesimal disturbances begin to grow.
Abstract: Visual, video, pressure, and conductance techniques were used to study time-varying disturbances in cocurrent flow in packed beds with vertical and horizontal columns. It is found that the trickle-pulse transition, as defined in previous studies, corresponds to conditions where traveling disturbances finaly become measurable, not the conditions at which infinitesimal disturbances begin to grow. Observations demonstrate that even if the liquid and gas are uniformly distributed initially, segregated, vertical flowing regions with higher or lower than average liquid holdup form after a short distance. Horizontal packed bed experiments, designed to study how regions of differing liquid holdup interact, indicate that the first type of disturbance is infiltration of gas into the liquid region. A simple model suggests that infiltration occurs if the pressure drop exceeds a value necessary to push gas through liquid-filled pores. Once infiltration is significant enough to form a third “bubbly” phase, traveling wave instabilities form and grow into pulses if sufficient column length is available. A three-layer Kelving-Helmholtz stability model is used to interpret the growth of disturbances in horizontal flows. Video obeservations of small-scale events in the bed failed to detect significant correlations between different regions. Thus it should be possible to describe flow behaviour in these systems with volum-averaged equations, as long as the presence of segregated regions is considered. Column diameter or thickness significantly affects the frequency of disturbances.
Patent•
06 Jun 1995TL;DR: In this article, an apparatus for quenching in hydroprocessing of a hydrocarbon feed stream is presented. But the quench medium is injected into the catalyst bed to reduce the gas component of the feed stream while simultaneously increasing the residence time and reducing the liquid velocity of the liquid component within the substantially packed bed of catalyst.
Abstract: This invention makes possible substantially continuous flow of uniformly distributed hydrogen and hydrocarbon liquid across a densely packed catalyst bed which substantially fills the entire volume of a reactor vessel. Catalyst are selected to be essentially the same density, shape and size at a design feed rate of liquids and gas to prevent ebullation of the packed catalyst bed at the design feed rates. The liquid and gas components of the hydrocarbon feed stream flow into the bed of catalyst and a quenching medium, which is preferably a liquid, is injected into the bed of catalyst. Injection of a liquid quench reduces the gas component of the hydrocarbon feed stream while simultaneously increasing the residence time and reducing the liquid velocity of the liquid component of the hydrocarbon feed stream within the substantially packed bed of catalyst. Injection of a liquid quench also increases penetration and contact of the liquid component into and on the surface area of the catalyst while simultaneously decreasing the viscosity of the liquid component. An apparatus for quenching in hydroprocessing of a hydrocarbon feed stream.
TL;DR: In this article, the application of a volume average Navier-Stokes equation for the prediction of pressure drop in packed beds consisting of uniform spherical particles is presented, and the development of the bed permeability from an assumed porous microstructure model is given.
Abstract: The application of a volume average Navier-Stokes equation for the prediction of pressure drop in packed beds consisting of uniform spherical particles is presented. The development of the bed permeability from an assumed porous microstructure model is given. The final model is quasi-empirical in nature, and is able to correlate a wide variety of literature data over a large Reynolds number range. In beds with wall effects present the model correlates experimental data with an error of less than 10%. Numerical solutions of the volume averaged equation are obtained using a penalty finite element method.
TL;DR: In this article, mass transfer efficiency and hydraulic characteristics of a 3.18 cm spray and a packed column for extracting ethanol from aqueous ethanol solution with supercritical carbon dioxide were investigated.
Abstract: Mass-transfer efficiencies and hydraulic characteristics of a 3.18-cm spray and a packed column for extracting ethanol from aqueous ethanol solution with supercritical carbon dioxide were investigated. Experiments were performed at 308.2, 313.2, and 323.2 K over a pressure range from 9.1 to 12.2 MPa. The influences of fluid properties, phase flow rates, column internals, and phase dispersion on mass-transfer efficiencies and hydraulic characteristics are discussed. An extension of a model for predicting mass-transfer efficiency in conventional liquid-liquid extraction to supercritical-fluid extraction was attempted. The model for mass-transfer efficiencies, developed for conventional spray and packed liquid-liquid extraction columns, was in good agreement with our experimental results.
TL;DR: In this paper, a countercurrent column, filled with structured gauze packing, was measured for the separation of a mixture of terpenes (d-limonene/1,8-cineole) by supercritical carbon dioxide, at 313 and 318 K and pressures up to 9 MPa.
Abstract: Supercritical fluid extraction (SFE) is an alternative separation method to more conventional processes such as liquid extraction and distillation. However, up to now, few works have been devoted to the investigation of the efficiency of countercurrent packed columns under supercritical conditions from a mass transfer point of view. Mass transfer in a countercurrent column, filled with structured gauze packing, was measured for the separation of a mixture of terpenes (d-limonene/1,8-cineole) by supercritical carbon dioxide, at 313 and 318 K and pressures up to 9 MPa. The extraction efficiency was determined in terms of the overall mass transfer coefficient. Operating lines for this process had an appreciable curvature due to a high miscibility of the two contacting phases. The real slope of these lines had to be estimated. Available mass transfer models for packed columns predicted efficiencies diverging to a great extent from the experimental results.
TL;DR: In this article, the effect of altering the DE (the equivalent sphere diameter of the packing) on the degree of axial dispersion in thermally short packings is discussed, and the significance of natural convection during heat exchanger operation is also demonstrated experimentally.
TL;DR: In this article, a simple model is presented which provides a qualitative understanding of axial dispersion in packed beds, and the model is verified by comparison with results in the literature.
TL;DR: In this paper, a packed bed solar air heater has been designed, fabricated and tested under the local weather conditions of Roorkee, India. Tests were conducted to cover a wide range of influencing parameters, including the geometrical and thermophysical characteristics of absorber matrices.
TL;DR: In this article, the behavior of axial compression columns (5 cm I.D.) was studied using IMPAQ C18 silica (average particle size 17 μm) as the stationary phase and water-methanol solutions as the eluent.
TL;DR: In this article, a new method of preparing stationary phases for packed capillary column supercritical fluid chromatography (SFC) is presented, where surface deactivation of silica particles was carried out by dehydrocondensation of the silicon hydride groups in polymethylhydrosiloxane with the silanol groups on the silica surface.
TL;DR: After selecting the best conditions, lignin peroxidase production in packed bed bioreactors operated at alternating growth-production cycles was achieved for 25 days obtaining an overall activity of 6136 U.
TL;DR: In this paper, a packed-bed reverse flow reverse flow reactor is provided for the endothermic dehydrogenation of ethylbenzene to styrene, where the flow direction is periodically reversed by alternating the ethylbene introduction between the reactor and the steam introduction between axially symmetric locations away from the reactor ends.
TL;DR: In this paper, the authors developed a mathematical model for predicting the mass transfer efficiency of packed saturators used for dissolved air flotation and derived a kinetic model based on concentration-driven diffusion and the Lewis-Whitman two-film theory.
TL;DR: In this paper, the axial dispersion coefficient of magnetically stabilized fluidized beds (MSFB) was evaluated by moment analysis of the impulse response curves, which was comparable to that of a packed bed and smaller than a fluidized bed.
TL;DR: In this article, the authors developed a general mathematical model with some improvements in mass, momentum and energy equations to simulate simultaneous transfer of heat and mass in the porous media unsaturated with liquid.
Abstract: The present paper develops a general mathematical model with some improvements in mass, momentum and energy equations, which introduce more transport mechanisms to simulate simultaneous transfer of heat and mass in the porous media unsaturated with liquid Numerical calculation results in two-dimension are obtained for the vertical packed bed with its right opening surface exposing to atmospherical environment The calculating data can demonstrate the cooling effect of the water evaporation for the bed if it is used as a cooling wall of building for room air-conditioning in the hot and dry climate
TL;DR: In this paper, the influence of pulsing frequency on several different reaction systems is explored based on models that describe a small local region within a multiphase packed-bed reactor.