Thermal Efficiency Improvement of the Pilot Plant Distillation Column by Vapor Recompression

The simulation and steady state operation of a vapor recompression pilot plant distillation column is studied in order to improve the thermal efficiency. A binary system of ethanol-water mixture is used. The simulation is carried through ASPEN PLUS version 9.3-1. Energy reduction of 89.26% is obtained comparing to the conventional distillation and the thermodynamic efficiency is improved from 11.32% to 13.28%. At the pilot plant distillation column, data acquisition, process control and operator interface of conventional and vapor recompression distillation are programmed in a distributed control system. The manipulated inputs for conventional distillation are cooling water and steam flow rate, whereas for vapor recompression are cooling water flow rate and heat transfer at the reboiler-condenser. From the experiment with the pilot plant, it is found that the actual energy consumption utilized is 17.04% and 6.25% higher than the result obtained from the simulation model for conventional distillation and vapor recompression distillation respectively. It is mostly due to the heat transfer to environment.