Plug-flow reactor optimum conversion

V decreases with increasing conversion of A. Thus, if it is possible to remove small amounts of V cheaply from large volumes of the reaction mixture, the optimum reactor configuration and mode of operation would involve the use of a plug flow reactor with low conversions of A per pass coupled with a separator to remove the product V and to recycle unconverted reactants. The exact conversion level to be employed will depend on an economic analysis of the combined reactor-separator system. 

Equation 3.33 allows the calculation of the optimum reaction zone size in the plug flow reactor, which is necessary to achieve the required degree of monomer conversion, as a function of the kinetic parameters of a chemical process k f and the required monomer conversion degree x. 

Optimum conversion in a continuous plug-flow reactor... 

It is particularly useful when one wants to carry out a relatively slow reaction in a continuous reactor, with a high degree of conversion. The plug flow reactor may not be a feasible alternative for various reasons. The most likely are the temperature control and the technical difficulty in approaching plug flow in a reactor of reasonable length. Even the temperature in the first CSTR in the cascade can usually be controll effectively, and by choosing a sufficient number of reactors the total reactor volume can be limited. It turns out that one will seldom use more than five CSTR s in series indeed for most processes a number of three appears to be close to the economic optimum. 

For both cases a plug flow reactor is optimum ( ), and for a prescribed temperature distribution, mixing is detrimental reducing conversion and reducing the curvature of a curved trajectory in component space. 

Figure 7. Tubular plug-flow addition polymer reactor effect of the frequency factor (ka) of the initiator on the molecular weight-conversion relationship at constant activation energy (Ea). Each point along the curves represents an optimum initiator feed concentration-reactor jacket temperature combination and their values are all different, (Ea = 32.921 Kcal/mol In ka = 35,000 In sec ...

Determine which setup, plug flow, mixed flow, or any two-reactor combination gives minimum r for 90% conversion of a feed consisting of Cao 100. Also find this r minimum. If a two-reactor scheme is found to be optimum, give between stages and r for each stage. 

The various types of reactors employed in the processing of fluids in the chemical process industries (CPI) were reviewed in Chapter 4. Design equations were also derived (Chapters 5 and 6) for ideal reactors, namely the continuous flow stirred tank reactor (CFSTR), batch, and plug flow under isothermal and non-isothermal conditions, which established equilibrium conversions for reversible reactions and optimum temperature progressions of industrial reactions. 

Using a developed plug-flow membrane reactor model with the catalyst packed on the tube side, Mohan and Govind [1986] studied cyclohexane dehydrogenation. They concluded that, for a fixed length of the membrane reactor, the maximum conversion occurs at an optimum ratio of the permeation rate to the reaction rate. This effect will be discussed in more detail in Chapter 11. They also found that, as expected, a membrane with a highly permselective membrane for the product(s) over the reactant(s) results in a high conversion. 

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