Try these exciting problems involving distillation of three components. We are forced to use mathematical methods because three or more dimensional graphs are hard to use. Well, there are some short-cut methods; for instance, assigning “key components”. However, the Lewis method works fine here – you just need to make more than one guess to start the stage-by-stage calculations.
Check out my YouTube video “Multicomponent Distillation” (catchy title, yes!). Solve the problem using a chemical process simulator like ChemCAD and make x, y, T, L, and V profiles to compare results. ChemCAD does not use the EMO assumption (you can tell by looking at the L and V profiles) and is likely using a better thermodynamic model for phase equilibrium. (I’ve used chemicals that are likely to be nearly ideal solutions.)
10.1 100 mol/s of a saturated liquid consisting of 20 mol% benzene, 40 mol% chlorobenzene, and 40 mol% 1,2-dichlorobenzene is fed to the second tray of a three-tray distillation column equipped with a total condenser and a partial reboiler, and operating at 1 atm. The reflux ratio is 0.5 and the bottoms flow rate is 40 mol/s. Determine all flow rates, compositions, and temperatures. Assume EMO and equilibrium trays.
10.2 50 mol/s of a saturated liquid consisting of 40 mol% benzene, 30 mol% toluene, and 30 mol% o-xylene is fed to the fourth tray of a seven-tray distillation column equipped with a total condenser and a partial reboiler, and operating at 1 atm. The reflux ratio is 1.0 and the bottoms flow rate is 50 mol/s. Determine all flow rates, compositions, and temperatures. Assume EMO and equilibrium trays.
