Engineering and Scale-up Aspects

2O3 tubes (1 cm) of hitk (now Fraunhofer IKTS Dresden) in the pilote module for O2 separation from air. 

7 Comparing Cryogenic Air Distillation, Pressure Swing and Permeation with Organic and Inorganic Membranes Economic Evaluation 

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Although this is one of the main barriers limiting engineering and scale-up aspects of perovskite membrane reactors, detailed information on the... 

Another important modeling aspect is the simulation of catalytic process parameters and reactor configurations. Such models are typically associated with process engineering, and involve computational fluid dynamics and heat- and mass-transfer calculations. They are essential in the process planning and scale-up. However, as this book deals primarily with the chemical aspects of catalysis, the reader is referred to the literature on industrial catalysis and process simulations for further information [49,56]. 

Three-phase fluidized beds and slurry reactors (see Figs. 30g-l) in which the solid catalyst is suspended in the liquid usually operate under conditions of homogeneous bubbly flow or chum turbulent flow (see regime map in Fig. 33). The presence of solids alters the bubble hydrodynamics to a significant extent. In recent years there has been considerable research effort on the study of the hydrodynamics of such systems (see, e.g., Fan, 1989). However, the scale-up aspects of such reactors are still a mater of some uncertainty, especially for systems with high solids concentration and operations at increased pressures it is for this reason that the Shell Middle Distillate Synthesis process adopts the multi-tubular trickle bed reactor concept (cf. Fig. 30e). The even distribution of liquid to thousands of tubes packed with catalyst, however poses problems of a different engineering nature. 

Sonochemical enhancement of reaction rates is caused by a phenomenon called cavitation. Therefore, we largely confine the treatment in this chapter to the chemical and reaction engineering (scale-up) aspects of cavitation and its associated effects (see Shah et al., 1999, for a detailed treatment). An alternative means of achieving the same result is by mimicking the ultrasonic effect by inducing hydrodynamic cavitation. Because of the practical importance of this technique, we conclude the chapter by outlining its main features. 

A large number of texts discuss the concept of similarity as applied to scale-up. The earliest unified approach to the application of concept of similarity in chemical process equipments was propounded by Johnstone and Thring (1957). The concept of dimensional analysis based similarity has become apart of all standard chemical engineering texts. Astarita (1985) has presented a lucid exposition of the subject matter. A recent book covering various aspects of dimensional analysis and scale-up in chemical engineering by Zlokamik (2002) is recommended for more detailed information. 

If the investigations are intended to develop an industrial production, the focus will be to optimize the operation conditions and to get base data for scale-up. In this case, the electrochemical properties of the experimental cell have to be equivalent with the planned technical cell. Thus, it is necessary to carry out experiments on a sufficient large scale, including lifetime tests of cell components. For industrial and engineering aspects, see for example, [1, 2, 3b, 4] (overview), [5c] (detailed), and [6, 7] (including theory). 

Chemical reactions carried out on an industrial scale are subject to control by processes such as mass transfer and heat transfer, which, in small-scale work, may often be reduced to negligible proportions by judicious choice of conditions. Volume 23 deals with these aspects of reaction kinetics, which must always be considered when significant scale-up is contemplated and which may be expected to be of paramount importance in industrial operations. The principles of chemical reactor design are treated in a form digestible by chemists and there is some emphasis on the way in which available kinetic data may be utilised by the chemical engineer. 

Engineering Aspects of Process Scale-Up and Pilot Plant Design... 

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