Experimental research on the process of compression and purification of CO2 in oxy-fuel combustion

•The optimal temperature and pressure for liquefaction were explored.•The overall average desulphurisation and denitration efficiencies exceeded 98%.•The existence of water and NOx were beneficial to the oxidation of SO2.•High CO2 concentration capture was realized. Oxy-fuel combustion is a leading potential CO2 capture technology for power plants. Thus, oxy-fuel technology has the highest requirement for CO2 purification. Compression and purification systems are important for oxy-fuel combustion. The tests in this study were conducted on a 50 kg/h CO2 compression and purification test platform, which is currently the largest oxy-fuel combustion platform in China. The CO2 compression and purification technology in oxy-fuel combustion was developed. The experiments verified the feasibility of the proposed technology and realised high concentration of CO2 capture. In addition, the optimal temperature and pressure for liquefaction were explored, and the optimal CO2 energy consumption was obtained. The overall average desulphurisation rate and denitration efficiencies were more than 98%, and the ratio change of n(SO2):n(NOx) exerted little effect on sulphur and nitrate purifications. The oxidation of SO2 was promoted with the increase in pressure. Moreover, the existence of water and NOx were beneficial to the oxidation of SO2, whereas NO had a slight promoting effect on the transformation of SO2. This study makes the replacement of traditional desulphurisation and denitration systems in oxy-fuel combustion power stations possible and might establish a technical foundation for large-scale oxy-fuel combustion demonstration projects.