Question

Find the flow rate of liquid entering into the enriching section if the internal reflux ratio is 1.5 times min. Given minimum reflux ratio is 0.95 and the gas flow rate is 35 mol/hr.

(a) 49.87 mol/hr

(b) 22.167 mol/hr

(c) 55.26 mol/hr

(d) None of the mentioned

I have been asked this question in an interview for internship.

My question is taken from Fractionation Column-Ponchon & Savarit Method in portion Distillation of Mass Transfer

Answer 1

The correct answer is (a) 49.87 mol/hr

The explanation: Internal reflux ratio = Liquid flow rate/ gas flow rate ( in nth plate of section)

                         1.5 *0.95 = L/35

                                  L= 49.87 mol/hr.