Heat Pump in Multicomponent Non-Ideal Distillation

 This study deals with reducing energy requirement in multicomponent distillation processes using heat pump technique. Heat pump with and without split tower technique was considered for two ternary (Methanol-Ethanol-Water and Acetone-methanol-Water), and one quaternary feed systems (n-Hexane – MCP – Ethanol and Benzene)and many variables have considered  such as operating pressure, feed composition, and fractional recovery.  The separation was carried out using one configuration for each feed system according to their non-ideality. In all cases the feed systems were assumed as a liquids at their boiling point and four degree of recoveries of 0.9, 0.925, 0.95, and 0.99 were studied,for feed systems a and b and 0.9 for feed system c. The operating pressure of each column in configuration was assumed to be changed from 0.5-3.0 atm in order to minimize the total energy consumption. With Split tower technique column 1 assumed to be operated at 0.5 atm and column 2 was operated at different operating pressure for six times from 0.5 to 3.0 atm, then the first column was assumed to be operated at 1.0 atm and the second changed from 0.5 to 3.0 until column one reached the operating pressure 3.0 atm this means that 36 possibilities were studied for feed system a and b and 216 possibilities for the quaternary feed system c.Total reboiler load, percentage saving in total energy consumption and percentage saving in total annual cost have been considered. Computer programmes written in FORTRAN 90 language were developed for the design of multicomponent distillation with and without heat pump system with and without split tower technique. The results show that the percentage reduction in energy requirements using heat pump was ranging from 12.14% to 76.02% when the same operating pressure was considered in each column in the configuration. While with split tower technique the percent reduction ranging from 12.02 % to 78.00 %. Also this technique give a percentage saving in total annual cost ranging from 10.00% to 77.36% for all cases studied. The present work was compared with previous work using heat integration [25] for the same systems and the same variables. The results show that when using heat pump technique there is an average of 20% saving in total energy consumption over that with heat integration.