Question

If the feed enters the distillation column at its dew point, then the slope of the Flash vaporization operating line is

(a) 0

(b) 1

(c) Between 0 and 1

(d) Infinity

I got this question in a national level competition.

This interesting question is from Flash Vaporization Line (q-line) in chapter Distillation of Mass Transfer

Answer 1

The correct option is (a) 0

The explanation is: If the feed at dew point means the feed condition is saturated vapour so the enthalpy of feed is same as the enthalpy of the vapour. Therefore the slope of the Q-line is 0. Since Q-line is the Flash vaporization operating line.