For ethanol-water system, the lowering of distillate quality from 95% to 92% will cause __________ plate requirement.
A. No change in theoretical
B. Marginal decrease in the number of
C. Major decrease in the number of
D. None of these
Answer: Option B
This Question Belongs to Chemical Engineering >> Mass Transfer
The correct answer is: C. Major decrease in the number of
Explanation:
In a distillation column, the number of theoretical plates required increases non-linearly as the desired distillate purity increases—especially near azeotropic or high-purity regions.
For the ethanol-water system, the separation becomes very difficult near 95% ethanol, due to the presence of an azeotrope at around 95.6% ethanol.
Reducing the distillate purity from 95% to 92% means moving away from the azeotropic point, which significantly eases the separation.
This results in a major decrease in the number of required theoretical stages/plates.
Therefore, the correct choice is:
C. Major decrease in the number of