(384c) An Innovative Design Methodology of Cryogenic Air Separation Process Based On Self-Heat Recuperation

In this research, an innovative design methodology of a cryogenic air separation process based on self-heat recuperation technology to reduce the energy consumption is developed. This design methodology is consisted from the following actions; 1) the heating and cooling load in the cryogenic air separation process is evaluated, 2) the process is divided into the functions to balance the heating and cooling load, and 3) the heat for cooling is recuperated and exchanged with the heat for heating based on self-heat recuperation technology for providing an internal heat circulation to reduce the energy consumption.

In the cryogenic air separation process based on the proposed design methodology, the heat of top vapor stream of distillation column is recuperated by compressors and exchanged with the heat of bottom liquid stream and feed stream by using the self-heat recuperation technology. As a result, not only the latent heat but also the sensible heat of the process stream are circulated in the process and the pressure of the column can be decreased compared with the high pressure part of the conventional cryogenic air separation process in which high and low pressure columns are combined to exchange nitrogen latent heat with oxygen latent heat. Thus, the energy input of the main compressor which is located in front of the column can be drastically reduced.

The simulation result demonstrates that the energy consumption for the cryogenic air separation process based on the proposed design methodology is more than 40% decreased as compared with the conventional cryogenic air separation process to produce oxygen 99.9% from air.