Scale-Up in Chemical Engineering

Author(s):  
Sean Moran ◽  
Marko Zlokarnik
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Dan Zheng ◽  
Wei Zou ◽  
Chuanfeng Peng ◽  
Yuhang Fu ◽  
Jie Yan ◽  
...  

A coupled numerical code of the Euler-Euler model and the population balance model (PBM) of the liquid-liquid dispersions in a spray fluidized bed extractor (SFBE) has been performed to investigate the hydrodynamic behavior. A classes method (CM) and two representatively numerical moment-based methods, namely, a quadrature method of moments (QMOM) and a direct quadrature method of moments (DQMOM), are used to solve the PBE for evaluating the effect of the numerical method. The purpose of this article is to compare the results achieved by three methods for solving population balance during liquid-liquid two-phase mixing in a SFBE. The predicted results reveal that the CM has the advantage of computing the droplet size distribution (DSD) directly, but it is computationally expensive if a large number of intervals are needed. The MOMs (QMOM and DQMOM) are preferable to coupling the PBE solution with CFD codes for liquid-liquid dispersions simulations due to their easy application, reasonable accuracy, and high reliability. Comparative results demonstrated the suitability of the DQMOM for modeling the spray fluidized bed extractor with simultaneous droplet breakage and aggregation. This work increases the understanding of the chemical engineering characteristics of multiphase systems and provides a theoretical basis for the quantitative design, scale-up, and optimization of multiphase devices.


Author(s):  
Cendrine Gatumel ◽  
Henri Berthiaux ◽  
Vadim E. Mizonov

Powder mixing is a part of our everyday life, but is the source of major industrial preoccupations. Mixing is widely used in many industries but until now design of mixing technology and mixing equipment belongs sooner to engineering art than to scientifically based calculation. Each branch of industry develops its own experience in the field mostly based on time and labour consuming expe-rimental research, and very often the obtained results cannot be used directly in another branch, i.e., the problem of mixing simulation and calculation is far from universality. This is why it is very im-portant to separate from particular sectorial problems the general intersectorial problems of theory and practice of mixing and concentrate the attention of researchers and engineers on them solution to build the general basis for scientifically based design of mixing technology and equipment. Current problems are associated with the definition of the homogeneity of the mixtures, the ways of measuring it, the sampling errors and techniques, the segregability of the mixtures in the powder handling operations, mixer choice, as well as mixer conception. In this paper, we review such aspects and try to draw some perspectives from a combined industrial experience – chemical engineering approach: the development of on-line monitoring techniques to assess homogeneity and further con-trol the process; the improvement of mixer’s scale up procedures, as well as the optimisation of mixer design and operation; the development of new mixing technologies, multifunctional, nearly “universal”, with a special emphasis on continuous processes; the completion of the actual standards on powder homogeneity by introducing structural information.  


„ , . large-scale production rate Scale-up ratio = — - n\ small-scale production rate Disperse system scale-up ratios may vary from 10 to 100 for laboratory to pilot-plant process translation and 10 to 200 for scaling from pilot-plant to commercial produc-tion. Actual production rates may vary considerably from expected production rates, since overall process efficiency is dependent on a wide range of factors. The process-ing of disperse systems, whether liquid-liquid or liquid-solid, is still relatively empiri-cal due to the substantial interfacial effects that predominate and control the relevant unit operations. Furthermore, unit operations may function in a rate-limiting manner as the scale of operation increases from the laboratory bench to the pilot plant to com-mercial production. Thus, although conventional wisdom suggests the necessity of scale-up studies, the appropriate approach is not necessarily initiated with miniaturized com-mercial processing systems [5]. The concept of scale-up has taken on a substantive regulatory aspect in more re-cent years with the issuance of Guidance 22-90 by the Food and Drug Administration's (FDA's) Office of Generic Drugs in September 1990 and the establishment of the Scale-Up and Post Approval Changes (SUPAC) Task Force by the FDA's Center for Drug Evaluation and Research. In May 1993, the American Association of Pharmaceutical Scientists, the Food and Drug Administration, and the United States Pharmacopeia cosponsored a workshop on the scale-up of liquid and semisolid disperse systems [6]. The primary finished product attribute to control during the scale-up of a disperse sys-tem, whether manufactured in identical, similar, or different equipment, is the degree of sameness of the finished product relative to previous lots. The consensus of the workshop committee was that four criteria be used to evaluate sameness: (1) adherence to raw material controls and specifications; (2) adherence to in-process controls; (3) adherence to finished product specifications; and (4) bioequivalence to previous lots. The aim of this chapter is to provide the formulator with an appreciation, on the one hand, of the complexity of the scale-up problem associated with disperse systems, and an awareness, on the other hand, that scale-up problems can be resolved, to a great extent, by drawing on the vast literature and experience of chemical engineering. In 1964, H. W. Fowler [7] initiated a series of progress reports in pharmaceutical engi-neering that appeared over time in the periodical Manufacturing Chemist. Fowler's ouevre was distinguished by his focus on fundamentals, i.e., on material properties and on operation and process mechanisms. His intention was "to look at the literature of chemical engineering and to discuss developments which are relevant to pharmacy." It is the present author's intention (in part, through this chapter on scale-up of disperse systems) to validate the interdisciplinary process that Fowler began more than 30 years

1998 ◽  
pp. 386-388

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