DIABATIC COLUMN OPTIMIZATION COMPARED TO ISOFORCE COLUMNS

This paper analyzes and compares optimization results for simulated di abatic columns Co theoretically derived optimization results from the isoforce method for the same system. The separation of ethanol and wat er is used to illustrate the two methods and bring out their common an d special features. The results, which are presented in McCabe-Thiele diagrams, show partial compatibility between the methods. The isoforce method is found to require total reflux ratios close to the azeotrope , and a reformulation of the method is suggested. It is also shown tha t the separation work obtained in an adiabatic stripping column can no t be achieved in a diabatic column without adding a (distributed) cond enser in the upper section of the column, or more plates. (C) 1997 Els evier Science Ltd.