Heat pump systems with mechanical compression for batch distillation

• Heat-pump systems with mechanical compression columns are studied for batch distillation.
• The separation of a close boiling hydrocarbon mixture is studied by dynamic simulation and cost calculations.
• The heat transfer in standard reboilers is rigorously simulated.
• By applying an external heat exchanger the payback time of vapour recompression system was reduced to 7 years.
• Vapour compression with a working fluid n-pentane gave similar payback time.

The operational and economic feasibility of different heat-pump systems with mechanical compression integrated to real batch distillation columns of different sizes is investigated. The systems studied are vapour recompression, vapour compression and vapour recompression with the application of an external heat exchanger. The issues of applying a mechanical compressor for a batch distillation column integrated with heat pump system are discussed. The separation of a low relative volatility mixture is investigated by rigorous simulation performed with a professional flow-sheet simulator. The systems studied are compared by payback times. For the vapour recompression system in the minimal payback time point the batch operation time was significantly longer than that of the conventional batch distillation. The payback time was considerably reduced by applying an external heat exchanger.