If Y which is ratio of mass of solvent to mass of solvent in liquid free phase: For extract is 0.5 (YD) For extract leaving stage N is 0.7 (YVN) Amount of extract is 100kg (D) Amount of solvent in cascade is 50 (SD) What is the extract reflux?

Correct Answer: 150
Since LR/D = (YD)+SD/D)-( YVN)/YVN-YD, LR= 100*(0.5+0.5)-0.7/0.7-0.5=150.