Reactor design procedure

Figure 3.29. Reactor design procedure with reactors having residence time distributions deviating from those of ideal reactors.

The concept of an overall rate based on the gas-phase bulk concentration and K° is not par ticularly helpful in the reactor design procedure when liquid and gas phases are in continuous flow (Smith, 1981). Instead, the overall rate should be expressed in terms of the bulk liquid concentration. The same analysis is followed for agitated slimy for continuous flow of both phases and for trickle-bed reactors. For a first-order reaction, using eq. (3.127) for the catalyst,... 

Kunii and Levenspiel s modiflcation (see their book, 1991, for original references) of the Davidson model and formulation of reactor design procedures for the different... 

The case studies presented in this chapter illustrate reactor design procedures for a carefully selected set of reacting systems wherein the physical dimensions of the reactor (diameter, height) and fixed and operating parameters (catalyst loading, superficial velocity, impeller speed, and other) were calculated. As a postscript to these studies, we would like to consolidate and emphasize certain fundamental and practical considerations in reactor selection and design. 

The kinetics of soluble and immobilized enzymes. Involved In reactions of soluble and Insoluble substrates appears to be sufficiently well studied over the last 20 years that reactor design procedures based on fundamental kinetics rate equations may be executed with considerable confidence. The application of such emzyme kinetics forms to structured models of microbial metabolism has also progressed, as this book documents. 

Nuclear power has achieved an excellent safety record. Exceptions are the accidents at Three Mile Island in 1979 and at Chernobyl in 1986. In the United States, safety can be attributed in part to the strict regulation provided by the Nuclear Regulatory Commission, which reviews proposed reactor designs, processes appHcations forUcenses to constmct and operate plants, and provides surveillance of all safety-related activities of a utiUty. The utiUties seek continued improvement in capabiUty, use procedures extensively, and analy2e any plant incidents for their root causes. Similar programs intended to ensure reactor safety are in place in other countries. 

Computational Scheme for Gas-Phase PFRs. A general procedure for solving the reactor design equations for a piston flow reactor using the marching-ahead technique (Euler s method) has seven steps ... 

As an example for precise parameter estimation of dynamic systems we consider the simple consecutive chemical reactions in a batch reactor used by Hosten and Emig (1975) and Kalogerakis and Luus (1984) for the evaluation of sequential experimental design procedures of dynamic systems. The reactions are... 

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

Since many reactions of this type involve a series of second-order processes, it is instructive to consider how one analyzes systems of this sort in order to determine the kinetic parameters that are necessary for reactor design purposes. We will follow a procedure described previously by Frost and Pearson (11). Consider the following mechanistic equations. 

This procedure obviously requires machine computation capability if it is to employed in reactor design calculations. Fortunately, there are many reactions for which the global rate reduces to the intrinsic rate, which avoids the necessity for calculations of this type. On the other hand, several high tonnage processes (e.g., S02 oxidation) are influenced by heat and mass transfer effects and one must be fully cognizant of their implications for design purposes. 

Various numerical procedures may be employed to solve the difference equations corresponding to equations 12.7.18 and 12.7.50 Many sophisticated numerical procedures may be employed, but they are more properly treated in textbooks dealing with numerical methods or more advanced texts in chemical reactor design. 

An approximate design procedure for packed tubular reactors entails the assumption of plug flow conditions through the reactor. Discuss critically those effects which would ... 

Figure 6.12 Graphical design procedure for reactors in series.

We illustrate the design procedure with the single reaction A - R with any kinetics. This procedure can be extended to other reaction types without difficulty. We first consider different ways of operating these reactors, and then compare these and point out when one or other is favored. 

Bulk density, or packing density, includes all pores and voids (interparticle spaces) in its calculation. This value depends on the form of the particle (powder, tablets, or extmdates) and the packing procedure. It is extensively used in reactor designing since this value connects the solid volume with that of the reactor. 

In all cases, a limiting reactor size may be found on the basis of mass transfer coefficients and zero back pressure, but a size determined this way may be too large in some cases to be economically acceptable. Design procedures for mass transfer equipment are in other chapters of this book. Data for the design of gas-liquid reactors or chemical absorbers may be found in books such as those by Astarita, Savage, and Bisio (Gas Treating with Chemical Solvents, Wiley, New York, 1983) and Kohl and Riesenfeld (Gas Purification, Gulf, Houston, TX, 1979). 

To investigate the impact of inhibition on reactor design, the procedure again is as follows (i) we have to develop the pertinent kinetic rate equation, (ii) insert this rate law into the equation for the reactor we intend to operate, and (iii) integrate over all applicable degrees of conversion. As the two most frequent cases of inhibition are the occurrence of substrate and (even more often) product inhibition, we will treat those two cases in the following section. We will just mention the equation for substrate inhibition, but we will develop step-by-step the equation for product inhibition. 

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