Author: Florent Allain Publisher: ISBN: Category : Languages : en Pages : 172
Book Description
Abstract: Packed bed reactors are widely used in the chemicals industry and have been studied carefully in the last century. Several reaction engineering models have been developed in order to predict the behavior of such reactors under specified conditions, in order to assist in the sizing during an industrial process conception. These reactors can be categorized using different parameters, and the bed-to- particle diameter ratio - N - is one of them. It has been shown that this parameter influences greatly the transfer phenomena that occur in the bed, and that for ratios under 10, particular attention is needed when considering the wall effects. An important point that has to be evaluated is the accuracy of the actual chemical reaction engineering models when simulating such beds as it is valid to question the hypothesis of a pseudo-continuum model when considering a low bed-to-particle diameter ratio bed. Through high precision Computational Fluid Dynamics calculations, several beds of particles are modeled and studied in term of mass dispersion and reaction rate distribution. Two reaction engineering models - a simple pseudo-continuum model with effectiveness factor, and a model we refer to as "Single pellet" model - and several correlations regarding Peclet numbers are then evaluated under the same conditions in order to determine their accuracy and reliability for that particular kind of bed. Two beds of N = 5.96 and N = 7.99 are studied for dispersion phenomena, and the bed of N = 5.96 is studied for reaction rate distribution. It is shown that the pseudo-continuum model of dispersion stands valid for the higher N, but that none of the correlations we used were able to correctly predict the behavior of the N = 5.96 bed at any of the Reynolds number we considered, only giving close behaviors. We were confronted with some difficulties regarding the reaction simulation under Fluent, but some comparisons were successfully made regarding species and reaction rate distribution in the bed.
Author: E. Alper Publisher: Springer ISBN: 9789024728749 Category : Science Languages : en Pages : 0
Book Description
The phenomenon of "mass transfer with chemical reaction" takes place whenever one phase is brought into contact with one or more other phases not in chemical equilibrium with it. This phenomenon has industrial, biological and physiological importance. In chemical process engineering, it is encountered in both separ ation processes and reaction engineering. In some cases, a chemical reaction may deliberately be employed for speeding up the rate of mass transfer and/or for increasing the capacity of the solvent; in other cases the multiphase reaction system is a part of the process with the specific aim of product formation. Finally, in some cases, for instance "distillation with chemical reaction", both objectives are involved. Although the subject is clearly a chemical engineering undertakin~, it requires often a good understanding of other subjects, such as chemistry and fluid mechanics etc., leading to publications in diversified areas. On the other har.d, the subject has always been a major field and one of the most fruitful for chemical engineers.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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.
Author: Andrzej Cybulski Publisher: CRC Press ISBN: 1420028006 Category : Science Languages : en Pages : 828
Book Description
Interest in structured catalysts is steadily increasing due to the already proven, as well as potential, advantages of these catalysts. Updating the comprehensive coverage of the first edition published in 1998 with the latest science and applications, Structured Catalysts and Reactors, Second Edition gives detailed information on all aspect
Author: David Reay Publisher: Butterworth-Heinemann ISBN: 0080983057 Category : Technology & Engineering Languages : en Pages : 624
Book Description
Process Intensification: Engineering for Efficiency, Sustainability and Flexibility is the first book to provide a practical working guide to understanding process intensification (PI) and developing successful PI solutions and applications in chemical process, civil, environmental, energy, pharmaceutical, biological, and biochemical systems. Process intensification is a chemical and process design approach that leads to substantially smaller, cleaner, safer, and more energy efficient process technology. It improves process flexibility, product quality, speed to market and inherent safety, with a reduced environmental footprint. This book represents a valuable resource for engineers working with leading-edge process technologies, and those involved research and development of chemical, process, environmental, pharmaceutical, and bioscience systems. - No other reference covers both the technology and application of PI, addressing fundamentals, industry applications, and including a development and implementation guide - Covers hot and high growth topics, including emission prevention, sustainable design, and pinch analysis - World-class authors: Colin Ramshaw pioneered PI at ICI and is widely credited as the father of the technology
Author: Octave Levenspiel Publisher: John Wiley & Sons ISBN: 047125424X Category : Technology & Engineering Languages : de Pages : 689
Book Description
Chemical reaction engineering is concerned with the exploitation of chemical reactions on a commercial scale. It's goal is the successful design and operation of chemical reactors. This text emphasizes qualitative arguments, simple design methods, graphical procedures, and frequent comparison of capabilities of the major reactor types. Simple ideas are treated first, and are then extended to the more complex.
Author: Florent Allain
Author: E. Alper
Author: Laxmangudi Krishnamurthy Doraiswamy
Author: 
Author: Erdoǧan Alper
Author: Andrzej Cybulski
Author: 
Author: David Reay
Author: Octave Levenspiel
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