OPTIMIZED AIR SEPARATION UNITS FOR OXY-COMBUSTION PROCESSES

Oxy-combustion is a promising technology to enable the capture of CO2 from fossil fuel based power plants. The core idea is to use O-2 instead of air for the combustion reaction, so that the flue gas is composed mainly of CO2 and H2O, thus avoiding N-2. The CO2 can be captured simply by condensing the H2O. The O-2 production process is the most important factor for the power penalty related to CO2 capture in oxy-combustion plants. Current air separation technologies for high volume O-2 production are based on cryogenic distillation. There is a large potential for improving this technology from a thermodynamic point of view. This paper presents a detailed exergy analysis of a cryogenic O-2 production process. The exergy losses in each sub-unit have been investigated. Based on results from the exergy analysis, ways to improve cryogenic O-2 production processes will be proposed.