If Y which is ratio of mass of solvent to mass of solvent in liquid free phase: For extract is 0.4 (YD) For extract leaving stage N is 0.6 (YVN) Amount of extract is 100kg (D) Amount of solvent in cascade is 40 (SD) What is the extract reflux?

Correct Answer: 100
Since LR/D = (YD)+SD/D)-( YVN)/YVN-YD, LR= 100*(0.4+0.4)-0.6/0.6-0.4=100.