Project ForgeChemical Reaction Engineering
Ideal Reactor Design
GATE 2014
Medium
In order to achieve the same conversion under identical reaction conditions and feed flow rate for a non-autocatalytic reaction of positive order, the volume of an ideal CSTR is
- always greater than that of an ideal PFR
- Balways smaller than that of an ideal PFR
- Csame as that of an ideal PFR
- Dsmaller than that of an ideal PFR only for first order reaction
Explanation
For any positive-order, non-autocatalytic reaction, the rate is highest at the feed (inlet) concentration and falls monotonically as conversion proceeds. A CSTR operates entirely at the LOW exit-concentration (low-rate) condition, while a PFR sees the full range of higher rates along its length — so a CSTR always needs a larger volume than a PFR for the same conversion.
Source: GATE CH 2014 (2014)
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