A saturated liquid mixture containing ethane, propene, propane, isobutane, butene and butane, whose composition (xF) is given below, is fed to a distillation column operating at 100 psia pressure at a rate of 100 kmol/hr. Distillation will produce a subproduct containing 95% by mole of isobutane in the feed. The by-product should not contain more than 1% by mole of the incoming propane.

A saturated liquid mixture containing ethane, propene, propane, isobutane, butene and butane, whose composition ( XF ) is given below, is fed to a distillation column operating at 100psia pressure at a rate of 100kmol/hr. Distillation will produce a subproduct containing 95% by mole of isobutane in the feed. The by-product should not contain more than 1% by mole of the incoming propane. There will be no butene and butane in the upper product, and no ethane and propene in the lower product. Distillate dew point: 36F; The boiling point of the bottom product is 127 F. The K values for the components at these temperatures are given in the table. a) Find the amount and composition of the top and bottom products. b) Calculate the minimum number of steps. c) Find the minimum backflow rate (it is recommended to start by trial and error with =2 ). d) What is the required theoretical number of racks when operating at 2 times the minimum RD value? e) Find the number of shelves in the enrichment and stripping zones