Additional Homework Problems

CDP12-FB

(b) Determine the minimum cost of the combination of the heat exchanger and reactor 2 to achieve an overall conversion of 95% (based on the feed to reactor 1). Air is to be used as the coolant and is available at 77°F and a rate of 100 mol /h. The cost of the reactor is

image 08eq12.gif

This cost includes both the catalyst and reaction container costs. The cost of the heat exchanger is

image 08eq13.gif

 
 
(c) Rather than using air as a coolant in the heat exchange, the feed stream to Reactor 1 is used. The feedstream enters the exchange at 600°F, is preheated to temperature T0, and is fed directly to Reactor 1. The stream then leaves Reactor 1 at temperature T1, again enters the air heat exchange (this time as the hot stream), exits the exchanger at T2, and enters Reactor 2. The weight of catalyst in Reactor 1 is equal to the weight of catalyst in Reactor 2. Determine the minimum cost of this reactor system (heat exchanger + Reactor 1 + Reactor 2) necessary to achieve an overall conversion of 92%. The cost functions are given by equations above. Reasonable first estimates of catalyst weight and T0 in each reactor are 100 lb and 910°F, respectively.

[2nd Ed. P8-34 (b) and (c)]