Reactor design outline

The treatment of reactor design in this section will be restricted to a discussion of the selection of the appropriate reactor type for a particular process, and an outline of the steps to be followed in the design of a reactor. 

A general procedure for reactor design is outlined below ... 

In spite of the drawbacks enumerated above, fluidized bed reactors have a number of compelling advantages, as we have noted previously. By proper design it is possible to overcome their deficiencies so that their advantages predominate. This book does not discuss in detail the manner in which this problem can be solved, although the design considerations outlined in subsequent sections of this chapter are quite pertinent. For detailed treatments of fluidized bed reactor design, consult the excellent reference works by Kunii and Levenspiel (3) and by Davidson and Harrison (4). 

As outlined in Chapter 5, Section 5.2.3.2 various approaches to overcoming the low rates of the hydroformylation of long chain alkenes in aqueous biphasic systems have been proposed. Some of these, such as the use of microemulsions [24-26] or pH dependent solubility [27], have provided improvements often at the expense of complicating the separation process. Perhaps the most promising new approaches involve the introduction of new reactor designs where improved mixing allows for... 

It must be pointed out again that even today confusion of terms can be observed when chemical engineers discuss miniplants or microplants . In most of these cases they identify with the terms mentioned above chemical plants made of glassware with volumes in the range of up to a few liters. To summarize, at that early stage no specialized micro structured reactors for production purposes were available. Most of the fabricated micro structured devices were made in terms of micro fabrication capabilities and not adapted to the chosen chemical process. It is no wonder that at first visionary theoretical work either had to be based on conventionally fabricated chemical reactors or did not outline reactor design in detail [30],... 

It is important to note that there is no global optimum reactor design that fits all purposes. There are always some trade-offs, and they should be evaluated on a case-by-case basis. Novel reactor designs have been constantly introduced to satisfy specific needs, some of which are outlined here. 

For use in reactor design the global rate should be calculable at all locations in the reactor. We suppose that the intrinsic rate equation is available. The problem is to evaluate the global rate corresponding to possible bulk concentrations Q, bulk temperatures 7, and flow conditions. If external and internal temperature differences can be neglected, the problem is straightforward and is essentially the reverse of the stepwise solution outlined in Sec. 12-1. The double-trial procedure is not necessary, because /(C) is known. The effective diffusivity of the catalyst pellet is required. The equations we need are Eq. (10-1) for external diffusion,... 

Although various such criteria cited in standard reactor design texts and in the literature purport to lead to safe operating regimes, their number and variety attest to the fact that at best they point in the direction of acceptable conditions. They should be used only if experimental tests of the kind outlined above are impossible. 

To conclude, the theoretical works combining chemical kinetics and dispersion phenomena in FIA reactors outline the limits of the continuous-flow concept and emphasize the importance of radial mass transfer rate [a, Eqs. (3.55) and (3.56)] on optimization of the reactor design. The... 

So far, this paper has considered the sources of metal-ion liquors and problems with traditional methods of treatment and the importance of a point of source strategy towards wastes has been emphasised. The possible role of electrochemical techniques has been outlined and illustrated by typical electrochemical reactions. In practice, the choice of reactor design and the reaction conditions are extremely important. 

As already mentioned, the form of the fundamental continuity equations is usually too complex to be conveniently solved for practical application to reactor design. If one or more terms are dropped from Eq. 7.2.a-6 and or integral averages over the spatial directions are considered, the continuity equation for each component reduces to that of an ideal, basic reactor type, as outlined in the introduction. In these cases, it is often easier to apply Eq. 7.1.a-l directly to a volume element of the reactor. This will be done in the next chapters, dealing with basic or specific reactor types. In the present chapter, however, it will be shown how the simplified equations can be obtained from the fundamental ones. 

The strategies covered in these chapters are all written in practically the same format a brief introduction followed by references to major works and texts an outline of principles methods of reactor design with illustrative problems where considered necessary and a listing of examples of their use, accompanied sometimes by brief descriptions of a few important ones. The lists are quite extensive in many cases consequently, the literature cited is also extensive. 

Our intention in this chapter is limited, however formulate approaches to the design of two main classes of catalytic reactors, fixed and fluidized bed briefly describe selected procedures along with a few numerical (or methodological) examples to illustrate their use and outline a procedure for incorporating the effects of catalyst deactivation in reactor design and operation. 

A schematic of a reactor made from a nonselective membrane for preventing the slip of an excess reactant is shown in Figure 24.2g. The principle of this reactor was outlined before. In the particular design shown, one of the reactants (5) is continuously recirculated on one side of the membrane so that complete conversion of A can be achieved on the opposite side without any slip. We refer to such a catalytic nonselective membrane reactor without packing as a CNMR-E. When packed, it is referred to as a CNMR-P. Another nonselective... 

This chapter is devoted to the discussion of thermal effects during chemical reactions with the main emphasis on how they can be controlled by using microdevices. A short introduction outlines the basic principles used in chemical reaction engineering without going into the details of thermostability of conventional flow reactors. The reader can find these topics in general text books on conventional chemical reactor design and engineering. 

One of the major uses of coal is to bum it directly in power plants our objective is to burn coal in an environmentally acceptable manner. This requires the removal of sulfur so that EPA standards for the omission of sulfur oxides in power plants are met. This paper briefly reviews the present state of the art for the chemical removal of sulfur from coal via an oxidation process. A brief summary of the existing sulfur removal processes and their economics along with the chemistry and kinetics of inorganic and organic sulfur removal from coal and the reactor design considerations are outlined. 

As mentioned in the previous chapter, chemical reactors are broadly classified as homogeneous (single phase) reactors and heterogeneous (multiphase) reactors. This chapter outlines various methods for design of homogeneous reactors. Design of ideal, non-ideal and non-isothermal reactors are discussed in detail. 

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