PS PROBLEM The feed to a distillation column is a 45 mol% benzene (B) and 55 mol% toluene (T) mixture at 50C. The vapor stream leaving the distillation column which contains 98 mol% benzene and the balance toluene goes to a total condenser. A quarter of the liquid condensate is withdrawn as a product at a rate of 25 kgmol/h while the remaining liquid condensate is returned to the top of the column. The overhead product (distillate) contains 95% of the benzene fed to the distillation column. The liquid stream leaving the bottom of the column goes to a reboiler. Part of the stream is vaporized. The vapor is recycled to the bottom of the column and the liquid is taken off as the bottoms product. A representation of the unit can be seen below. Additional information: The average heat capacity of the feed is 159 kJ/(kgmol K) and the average latent heat is 32099 kJ/kgmol. a) What is the reflux ratio? b) What is the molar flow rate of the feed stream and the molar flow rate and composition of the bottoms product? c) Determine the number of theoretical trays. d) On which tray is the feed introduced? e) If the overall tray efficiency is 60%, what is the actual number of trays in the column? f) What would be the theoretical number of trays if there would be total reflux? PS PROBLEM The feed to a distillation column is a 45 mol% benzene (B) and 55 mol% toluene (T) mixture at 50C. The vapor stream leaving the distillation column which contains 98 mol% benzene and the balance toluene goes to a total condenser. A quarter of the liquid condensate is withdrawn as a product at a rate of 25 kgmol/h while the remaining liquid condensate is returned to the top of the column. The overhead product (distillate) contains 95% of the benzene fed to the distillation column. The liquid stream leaving the bottom of the column goes to a reboiler. Part of the stream is vaporized. The vapor is recycled to the bottom of the column and the liquid is taken off as the bottoms product. A representation of the unit can be seen below. Additional information: The average heat capacity of the feed is 159 kJ/(kgmol K) and the average latent heat is 32099 kJ/kgmol. a) What is the reflux ratio? b) What is the molar flow rate of the feed stream and the molar flow rate and composition of the bottoms product? c) Determine the number of theoretical trays. d) On which tray is the feed introduced? e) If the overall tray efficiency is 60%, what is the actual number of trays in the column? f) What would be the theoretical number of trays if there would be total reflux
