Recent progress in two phase gas—liquid mass transfer in packed beds
About: This article is published in Chemical Engineering Journal.The article was published on 1976-01-01. It has received 98 citations till now. The article focuses on the topics: Phase (matter) & Mass transfer.
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TL;DR: In this article, a review of relevant experimental observations and modeling of high-pressure trickle-bed reactors, based on recent studies, is presented, and the effects of high pressure operation, which is of industrial relevance, on physicochemical and fluid dynamic parameters are discussed.
Abstract: A concise review of relevant experimental observations and modeling of high-pressure trickle-bed reactors, based on recent studies, is presented. The following topics are considered: flow regime transitions, pressure drop, liquid holdup, gas−liquid interfacial area and mass-transfer coefficient, catalyst wetting efficiency, catalyst dilution with inert fines, and evaluation of trickle-bed models for liquid-limited and gas-limited reactions. The effects of high-pressure operation, which is of industrial relevance, on the physicochemical and fluid dynamic parameters are discussed. Empirical and theoretical models developed to account for the effect of high pressure on the various parameters and phenomena pertinent to the topics discussed are briefly described.
343 citations
TL;DR: In this paper, the authors present the techniques, results, and opinions on mass-transfer coefficients and interfacial areas in most types of absorbers and reactors in a gas-liquid mass transfer with chemical reaction.
Abstract: Publisher Summary At the heart of the liquid-phase processes, gas scrubbing process, manufacturing of pure products, and biological systems, there exists the absorber or the reactor of a particular configuration best suited to the chemical absorption or reaction being carried out. Its selection, design, sizing, and performance depend on the hydrodynamics and axial dispersion, mass and heat transfer, and reaction kinetics. This chapter focuses on the subject of mass transfer with chemical reaction. It presents the techniques, results, and opinions on mass-transfer coefficients and interfacial areas in most types of absorbers and reactors. To study gas–liquid mass-transfer phenomena, it is convenient to consider steady-state situations in which the composition of the gas and the liquid are statistically constant when averaged over time in a specified region, such as a short, vertical slice of a tubular column or the entire volume of a single-compartment agitated vessel. Useful predictions have been developed for describing the behavior of complicated systems, using highly simplified models that simulate the situation for practical purposes without introducing a large number of parameters. The procedure differs depending on whether physical or chemical absorption is involved.
290 citations
TL;DR: Theoretical and phenomenological aspects of trickle-bed reactors as reported in a wide number of papers of the last 35 years have been reviewed in this article, where several engineering topics have been focused by trying a critical interpretation of the attained results.
169 citations
TL;DR: In this paper, the mass transfer and pressure drop of a rotating packed bed were investigated under 13−273 equiv of gravitational force with two packings, and the results indicated that the mass-transfer coefficient (KGa) was enhanced due to the centrifugal force as compared to a conventional packed bed.
Abstract: The mass transfer (stripping of ethanol) and pressure drop (water−air) of a rotating packed bed were investigated under 13−273 equiv of gravitational force with two packings. The results indicated that the mass-transfer coefficient (KGa) was enhanced due to the centrifugal force as compared to a conventional packed bed. An empirical correlation was also proposed, suggesting that the KGa value depends on the GrG number to the power of 0.25. As to pressure drop, the gas rate seems to be a more important factor than the liquid rate because of less liquid holdup under centrifugal force. A semiempirical equation was also developed to correlate the pressure drop data with good agreement.
137 citations
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TL;DR: The analysis and design of multiphase reactors is one of the most intensely studied areas of chemical reaction engineering as discussed by the authors, and it may not always be clear which reactor type is most advantageous for a particular reaction.
Abstract: ' analysis and design of multiphase reactors is one of the most I intensely studied areas of chemical reaction engineering. The ^r types of industrial fluid/solid reactors can be broadly divided into two categories: one where the solids are fixed and the other where the solids are in a suspended state. Solids suspension may be achieved by stirring (stirred slurry reactor), by gas-induced liquid motion (slurry bubble column or air-lift) or by forced fluid flow (three-phase fluidised bed). These reactors are sketched in Figure 1. For a particular reaction, it may not always be clear which reactor type is most advantageous. Different types have to be considered or are actually used for the same conversion (e.g. FischerTropsch Synthesis). More recently Krishna and Sie (1994) recommended a three level strategy for the selection of type of multiphase reactor for a given process. Their selection criteria is conveniently split into three, separate, sequential decisions on the following aspects:
112 citations
References
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TL;DR: In this article, the average bubble diameter and conditions of bubble generation are obtained for the extreme cases when no coalescence is observed and the coalescence occurs at the maximum-rate.
Abstract: Bubbles which have been just generated from the porous plate are small and have an equal size, but sometime coalescence of these small bubbles occurs at a location slightly removed from the distributor, where the gas holdup is very large. Therefore, large and wide size distribution of bubbles are observed. This occurs easily in pure water and pure solvents. The surface active substances in water and solvents obstruct this coalescence of bubbles. In concentrated inorganic salt solutions, this obstruction is also recognized. For the extreme cases when no coalescence is observed and the coalescence occurs at the maximumrate, the correlations of the average bubble diameter and the conditions of bubble generation are obtained.
900 citations
TL;DR: In this paper, a generalized correlation is proposed for the values of effective interfacial area duing Vaporization, Absorption with and without Chemical Reaction and the value of wetted surface area in terms of dimensionless numbers.
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