Abstract

Heat pumping has been used in reducing energy consumption in distillation columns. However, the effects of some parameters have not been taken into consideration in the determination of energy consumption in such systems. The consideration of these parameters may give more insight into the performance of such systems. The purpose of this study was to develop a thermodynamic simulation model for comparing two distillation systems: one operating with pressure increase across the compressor and the other with negligible pressure increase over the compressor. An ethanol-water conventional distillation column with direct vapour recompression was used as a case study. The study shows that when the pressure across the compressor increases, the compressor power input, compressor displacement rate, compressor heat load rate and total energy consumption increased while the coefficient of performance and compressor volumetric efficiency decreased. The significance of this work is the provision of information for the determination of energy effectiveness as well as appropriate capacity of the auxiliary equipment for ethanol separation which is becoming a more competitive fuel.

Key words: Compressor, distillation column, energy, pressure drop, vapour recompression.