Oxy-fuel combustion power systems can utilize the cold energy released during the liquefied natural gas(LNG)regasification to reduce the power consumption of CO_(2) capture,but the specific LNG cold energy consumption of CO_(2) capture is still too large.To recover more CO_(2) with the limited LNG cold energy at a low energy cost,a novel natural gas-fired oxy-fuel power system with the cascade utilization of LNG cold energy is proposed in this work,where the LNG cold energy could be sequentially utilized in the air separation unit and the CO_(2) recovery process.The new system is evaluated with the Aspen Plus software.The results show that the net electrical efficiency and the specific primary energy consumption for CO_(2) avoided(SPECCA)of the new system are comparable to those of the chemical looping combustion cycle,and superior to those of the conventional O_(2)/CO_(2) cycles.Moreover,the specific LNG needed for CO_(2) avoided(SLNCC)of the new system is more than 67.2%lower than the existing oxy-fuel power systems utilizing the LNG cold energy.Furthermore,it is found that the O_(2) purity of 97.0 mol.%and the CO_(2) capture ratio of 97.0%are optimal conditions,because the SPECCA,the specific exergy consumption for CO_(2) avoided(SECCA)and the SLNCC are at the minimum of 1.87 GJLHV⋅t_(CO_(2))^(−1),2.60GJ⋅t_(CO_(2))^(−1) and 1.88tLNG⋅t_(CO_(2))^(−1),respectively.Meanwhile,the net electrical efficiency and the exergy efficiency of the new system reach 51.51%and 49.23%,respectively.
LIU RongXIONG YongqiangKE LiyingLIANG JiachengCHEN DengjieZHAO ZhongxingLI Yajun
