Chapter 2: Conversion and Reactor Sizing

Example - Use Levenspiel plots to calculate conversion from known reactor volumes

Pure A is fed at a volumetric flow rate of 1000 dm³ /h and at a concentration of 0.005 mol/dm³ to an existing CSTR, which is connected in series to an existing tubular reactor.

If the volume of the CSTR is 1200 dm³ and the tubular reactor volume is 600 dm³ , what are the intermediate and final conversions that can be achieved with the existing system? The reciprocal rate is plotted in the figure below as a function of conversion for the conditions at which the reaction is to be carried out.

Solution

By trial and error, we find that a conversion of 0.6 gives the appropriate CSTR volume of 1200 dm³

Therefore, the intermediate conversion is X = 0.6

Similarly for the PFR, through trial and error, we find that a conversion of 0.8 gives the appropriate PFR volume of 600 dm³

Therefore, the final conversion is X = 0.8

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