General Population Balance Modelling of Unpremixed Feedstream Chemical Reactors: A Review

Ritchie, B. W.; Tobgy, A.H.

doi:10.1080/00986447808960467

Cited by 22 publications

(2 citation statements)

References 100 publications

(119 reference statements)

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“…They are proposed to correct drawbacks of the original approaches, but introduce some additional complexity (Goto and Matsubara, 1975;Ritchie and Tobgy, 1978;Call and Kadlec, 1989).…”

Section: Fluid-particle Modelsmentioning

confidence: 99%

Modeling of imperfect mixing and its effects on polymer properties

Zhang

Ray

1997

AIChE Journal

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“…They are proposed to correct drawbacks of the original approaches, but introduce some additional complexity (Goto and Matsubara, 1975;Ritchie and Tobgy, 1978;Call and Kadlec, 1989).…”

Section: Fluid-particle Modelsmentioning

confidence: 99%

Modeling of imperfect mixing and its effects on polymer properties

Zhang

Ray

1997

AIChE Journal

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“…Of the many mechanistic models (e.g., mixing length models, surface renewal models), we consider the "population balance" models to hold the most promise for complex chemical reactor analysis. Population balance models have been broadly classified by Ritchie et al (1978) as (1) Coalescence-Redispersion Models and (2) Environment Models.…”

Section: Introductionmentioning

confidence: 99%

Four environment model of mixing and chemical reaction. Part I. Model development

Mehta

Tarbell

1983

AIChE Journal

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A new mathematical model (the four environment model) to describe turbulent R. V. MEHTA and J. M. TARBELL flow chemical reactors with complex reactions and separate reactant feed streams is developed. The feed stream residence time distributions, the batch chemical kinetics, and a single turbulent micromixing parameter, which may be estimated Department of Chemical Engineering from direct turbulence theory, are required as input information to the model. The and Center for Air Environment Studies model is computationally efficient as it involves only ordinary differential equa-The Pennsylvania State University tions. University Park, PA 16802 SCOPEMixing and chemical reaction are concurrent phenomena in many chemical reactors, particularly those of industrial scale. The design and development of reactors with unmixed feedstreams, complicated large-scale mixing patterns, and competing chemical reactions is a challenge which often requires significant pilot-plant experience. A mathematical model capable of describing these complex chemical reactor phenomena is clearly desirable. However, most existing models are either too complex-involving many empirical parameters, or too inefficient computationally-requiring the solution of coupled partial differential equations or Monte Carlo simulations. A notable exception is the three environment model of Ritchie and Tobgy (1979), which is computationally efficient and provides a reasonable description of the mixing processes. Unfortunately, the three environment model does not properly account for the effect of micromixing on the selectivity of competing reactions--q significant problem in industrial reactor design.Our objective in this work was to develop a computationally efficient mathematical model of mixing and chemical reaction which would retain the overall structure and desirable features of the three environment model while allowing a more realistic description of the effect of micromixing on selectivity of competing reactions. CONCLUSIONS AND SIGNIFICANCEWe have developed a computationally efficient chemical reactor model (the four environment model), having an ordinary differential equation structure, which can account for competing chemical reactions, arbitrary macromixing patterns, and turbulent micromixing of unmixed reactants. The input information required by the model includes: the (perfectly mixed) batch chemical kinetics; the residence time distribution function for each reactor feedstream; and a single micromixing parameter which may be determined by a reactive tracer experiment. An analogy between the four environment model and isotropic turbulence mixing as expressed in the theories of Corrsin (1964) and Rosensweig (1964) provides a means of estimating (corre-lating) the micromixing parameter from knowledge of the reactor geometry and the power input. The four environment model is a refinement and extension of the three environment model of Ritchie and Tobgy (1979). By adding an additional "leaving environment" (the three environment model has only o...

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Mixing in continuous crystallizers

Tavare

1986

AIChE Journal

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The review is concerned primarily with some aspects of mixing in continuous crystallizers and recognizes the central importance of the interplay between the mixing and crystallization (or precipitation) processes in the design and performance evaluation of industrial crystallizers. The paper adopts a unifying treatment from a chemical reaction engineering viewpoint in which the Lagrangian approach to mixing in crystallizer systems is emphasized. The concepts of macro-and micromixing applied to crystallization configurations have been introduced with due emphasis on the modeling efforts. The present state of knowledge in various related areas of continuous mixing is assessed to help direct future trends in research. N. S. Tavare Department of Chemical EngineeringUniversity of Manchester Institute of Science and TechnologyManchester, M60 lQD, England SCOPEIn recent years notable progress has been achieved in applying formalized unifying chemical reaction engineering principles to the analysis, simulation, and design of crystallizer configurations, but one significant gap in our understanding of crystallization processes is their interaction with mixing process. Using an analogy with the mixing description conventionally used in chemical reactors, this paper attempts to formalize the interplay between mixing and crystallization from the Lagrangian perspective. The mixing process is generally characterized by two distinct and independent elements, macro-and micromixing. The objectives of this review are to report the present state of the art and to direct further work on the characterization of mixing and its effects on the overall performance in conventional crystallizer configurations. Such a review may help in evaluating some of the research trends in this field. CONCLUSIONS AND SIGNIFICANCEThe present article attempts a comprehensive treatment of mixing in continuous crystallizers from the Lagrangian perspective and has resulted in a recognized and straightforward chemical reaction engineering approach to the analysis of crystallization processes. The first part of the review deals with macromixing aspects, which covers major developments in analysis of residence time and crystal size distributions (RTD and CSD) with particular reference to modeling work. Clearly, CSD modeling is and will remain a popular and central topic of crystallization research. Both RTD and CSD studies should become more detailed and widespread for their greater engineering utility in the design, performance evaluation, and control of industrial units.The second part of the review highlights the relatively new and important area of micromixing, i.e., mixing at the molecular scale. A small number of process simulation studies at extreme levels of micromixing have clearly demonstrated the enormous effects of the micromixing level on overall crystallizer performance. This may provide a comparatively sensitive and useful indicator of intermediate levels of micromixing. Characterization of real vessels of crystallization systems with complex no...

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General Population Balance Modelling of Unpremixed Feedstream Chemical Reactors: A Review

Cited by 22 publications

References 100 publications

Modeling of imperfect mixing and its effects on polymer properties

Modeling of imperfect mixing and its effects on polymer properties

Four environment model of mixing and chemical reaction. Part I. Model development

Mixing in continuous crystallizers

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