Power reduction in air separation units for oxy- combustion processes based on exergy analysis

摘要

Oxy-combustion is a competitive technology to capture CO_2. The oxygen production process has caused the largest power penalty related to CO_2 capture. Current air separation technologies for high volumn O_2 production are based on cryogenic distillation. In this process, the air compressor and the distillation system cause the two largest exergy losses. This paper has performed an exergy analysis on an air separation unit and analyzed ways to reduce the exergy losses. An improved air separation unit has been studied to compare the exergy losses with the previous unit. McCabe-Thiele diagrams have been sketched to illustrate how to reduce the irreversibilities in the distillation system.