Question

Consider the following labeled flowchart for a simple chemical process based on reaction A -> B and predict the overall and single-pass conversion of the process?

(a) 100%, 70%

(b) 100%, 50%

(c) 100%, 75%

(d) 100%, 55%

I have been asked this question by my school principal while I was bunking the class.

Question is taken from Material Balances with Recycle, By in chapter Material Balance of Bioprocess Engineering

Answer 1

Right choice is (c) 100%, 75%

Explanation: Overall conversion: Based on the streams that enter and leave the overall process.

Overall conversion =  (moles of reactants in fresh feed-moles in the output of the overall process)/(moles of reactant in fresh feed)

Therefore, the overall conversion of A is from equation:

Overall conversion = ((75 mol A/min)in –(0 mol/min)out)/((75 mol A/min)out) × 100% = 100%

Single-pass conversion: Based on streams that enter and leave the reactor.

Overall conversion = (moles of the reactants fed into the reactor-moles that exiting the reactor)/(moles of reactant fed into reactor)

Therefore, the single-pass conversion from equation is:

((100 mol A/min)in-(25 mol A/min)out)/((100 mol A/min)in) × 100% = 75%.