In order to solve the global warming and reduce greenhouse gas emissions, it was developed the CO2 capture technology by oxy-fuel combustion. But there was a problem that the economic efficiency is low, because of high oxygen production cost. ASU(Air Separation Unit) is known to be most suitable technology to produce large quantity of oxygen production.(>2,000TPD) But the most of conventional type ASU are optimized to produce the high purity oxygen(>99.5%), nitrogen and argon. If the oxygen is only produced without other gases at ASU, the production cost will increase.

The oxy-fuel combustion needs only the large quantity oxygen and the low purity oxygen(90~97%) can be used. If the ASU process is optimized for low purity oxygen producing, it is possible to reduce the production cost of oxygen by improving the efficiency.
This study is to improve the efficiency by ASU process optimization and to develop an ASU process suitable for oxy-fuel combustion. For that, the efficiency of ASU plant was checked and analyzed to propose the process improvement direction. To analyze the efficiency of ASU, exergy analysis can be used. The exergy analysis provides the information of used energy in the process, the location and size of exergy destruction. The ASU cycle was selected for oxy-fuel combustion and conducted the process optimization for ASU cycle.
For the ASU process optimization, ASU cycle with low operating pressure was selected(Dual condenser, Dual condenser with BAC, Three column type ASU cycle), and the process parameters of the cryogenic heat exchanger and cryogenic column was optimization. Also, M.P. GN2 was produced to recovery energy and minimize the power consumption. As a results, ASU process that has 16 ~ 25% lower power consumption than conventional process was proposed according to ASU cycle. The oxygen production cost was calculated to evaluate the economic feasibility of ASU, and the economic impact of oxygen production capacity, power cost, and ASU lifetime was evaluated.
This study that optimized the process to reduce the oxygen production cost and evaluated the economic feasibility can supply the application criteria of the ASU for oxy-fuel combustion.