(61c) Advanced Self-Heat Recuperative Distillation System

In the last several years the authors have been developing the self-heat recuperation technology for the heating and cooling thermal processes in which the heat of an effluent stream is recuperated and recycled for feed stream heating by the adiabatic compression of gas and/or vapor. This SHR technology has been applied for the heat circulation of various thermal processes such as distillation, drying, CO2 chemical absorption, cryogenic air separation, pressure swing adsorption, sea water desalination, etc., leading to a considerable amount of energy saving. In the case of the distillation systems the overhead vapor from is pressurized by compressors and its temperature is increased by adiabatic compression. The duties of reboiler and feed heater are supplied by the heat of the discharged streams from the compressors. This results that the heat of the process stream is circulated without the need for any additional heat, and, thus, the energy consumption of a process can be greatly reduced. However, if the boiling temperature difference between two components is large, the energy consumption of distillation becomes large because the minimum work required for the heat circulation by the self-heat recuperation is almost proportional to the temperature increase by the adiabatic compression.

In the present paper, a novel self-heat recuperative distillation system with a large temperature difference between top and bottom of column is described based on the exergy and exergy analysis.