Oxy-fuel combustion is one of the most promising methods for CO2
capture and storage (CCS) but the operating costs—mainly due to the need for oxygen production—usually lead to an obvious decrease in power generation efficiency. An “oxy-enrich combustion” process was proposed in this study to improve the efficiency of the oxy-fuel combustion process. The oxidizer for oxy-enrich combustion was composed of pure oxygen, air and recycled flue gas. Thus, the CO2
concentration in the flue gas decreased to 30–40%. The PSA (pressure swing adsorption), which has been widely used for CO2
removal from the shifting gases of ammonia synthesis in China, was applied to capture CO2
during oxy-enrich combustion. The technological economics of oxy-enrich combustion with PSA was calculated and compared to that of oxy-fuel combustion. The results indicated that, compared with oxy-fuel combustion: (1) the oxy-enrich combustion has fewer capital and operating costs for the ASU (air separation unit) and the recycle fan; (2) there were fewer changes in the components of the flue gas in a furnace for oxy-enrich combustion between dry and wet flue gas circulation; and (3) as the volume ratio of air and oxygen was 2 or 3, the economics of oxy-enrich combustion with PSA were more advantageous.
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