Question

SELECT ALL THAT OCCURS WHEN THE REBOIL RATE IS INCREASED.

A) THE BOTTOMS FLOW RATE IS INCREASED;

B) THE DISTILLATE CONCENTRATION IN THE BOTTOMS DISCHARGE IS INCREASED;

C) THE COLUMN TEMPERATURE IS INCREASED;

D) THE NUMBER OF THEORETICAL PLATES INCREASES IN A PACKED COLUMN;

Answer 1

Ans

We will analyze all the given options.

Option A

On increasing the Reboil rate,

It means the bottom. product is not obtained, it is being more recycled than withdrawing as a final product. Thus it decreases the bottom distillate rate.

Option A is incorrect.

Option B

On increasing the Reboil rate,

It increases the contact between the vapor and the liquid, due to it less volatile component is more transferred and the efficiency of separation decreases. Thus the distillate concentration in bottom discharge increases.

Option B is correct.

Option C

On increasing the Reboil rate,

Reboil stream has a higher temperature than the liquid temperature in which both contacts inside the column. The column temperature is increased

Option C is correct.

Option D

On increasing the Reboil rate,

From the SOL equation

y = L*x/(L-B) + B*xb / (L-B)

It will increase the term L/(L-B) i.e. slope of the stripping line. It will further away from the 45° line in the McCabe-Thiele diagram and will have more number of stages than before.

Option D is correct.