Overall fraction conversion

Obviously this approach is not easily extended to cascades containing more than three reactors and, in those cases, an alternative trial and error procedure is preferable. One chooses a reactor volume and then determines the overall fraction conversion that would be obtained in a cascade of N reactors. When one s choice of individual reactor size meets the specified overall degree of conversion, the choice may be regarded as the desired solution. This latter approach is readily amenable to iterative programming techniques using a digital computer. 

If the system is to operate isothermally at 50 °C where the reaction rate constant is equal to 0.9 m3/kmole ksec, determine the reactor volume necessary to achieve an overall fraction conversion of 0.80. Species A is to be fed at a rate of 0.3 mole/sec and an initial A concentration of 2 kmoles/m3. 

Consider the reaction studied in Illustration 10.1. Autothermal operation is to be achieved using a CSTR with an effective volume of1000 gal followed by a PFR of undetermined volume. Pure species A enters at a rate of 40.0 gal/hr and at a temperature of 20 °C. The overall fraction conversion is to be 0.97. This flow rate and conversion level will suffice to meet the annual production requirement of 2 million lb of B. Both the CSTR and the PFR are to be operated adiabatically. What PFR volume will be required, and what will be the temperature of the effluent stream ... 

For the proposed design the reactor volumes are both 0.8 m3, the input volumetric flow rate is 1.10m3/ksec, and the overall fraction conversion of the initial B is to be 0.80. Since the reaction is carried out in dilute liquid solution, the effective heat capacity of the liquid mixture is substantially unaffected by the reaction and may be regarded as a constant that is equal to 3.47 J/cm3 °K. If the initial concentration of species B is 5.6 kmole/m3 and the feed stream enters at 70 °C, determine the required heat transfer area for each reactor. 

The F(t) curve for a system consisting of a plug flow reactor followed by a continuous stirred tank reactor is identical to that of a system in which the CSTR precedes the PFR. Show that the overall fraction conversions obtained in these two combinations are identical for the case of an irreversible first-order reaction. Assume isothermal operation. 

Determine the overall fractional conversion of naphthalene, and the selectivity to phthalic anhydride. 

Find the following (a) the specific rate at 50 C (b) the concentration Cal leaving the CSTR (c) the concentration Ca2 entering the storage tank (d) the overall fractional conversion. 

The lag between density cell response and reactor events were considerably less for this example and the figures ignore any correction. After establishing a "steady state" response to the monomer feed (about 160 minutes into the reaction), the incremental increase of the feed rate is seen not to alter the overall fractional conversion since the rate of polymerization increases to parallel the monomer feed rate. At the end of this set of data the rate is 2-3 times that observed earlier before the feed. 

Th = temperature of the heating coils XA = overall fractional conversion of A... 

The single-pass (mole) balance on A provides the crucial information to evaluate R. WiU an A balance, or total balance, for the overall process enable you to solve for / Try one and see why not. What is the overall fraction conversion of A for the entire process Does that information help you solve fori ... 

It is noteworthy that a true continuously stirred tank reactor is perfectly mixed a recycle loop cannot be used to further improve agitation or the value of In practice, particularly useful methods of improving the overall fractional conversion are (1) batch recirculation of the electrolyte through the reactor from a storage tank (section 2.5.4) or (2) the use of a number of reactors in hydraulic series, i.e. a cascade arrangement (see section 2.5.5). 

The overall fractional conversion for the continuously stirred tank reactor in batch recycle is therefore ... 

The symbols /, and are the initial values of/j and. The right-hand side of Equation 16.151 is the overall fractional conversion of both monomers, where M is the concentration of both monomers taken together, and is the initial value of M. This equation can be solved implicitly, or values of monomer mole fractions (/, and /g can be assumed and the total monomer fractional conversion computed directly. 

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