Thermodynamic and economic feasibility assessment on staged pressurized oxy-combustion coupled with sCO₂ cycle...

Oxy-combustion is a promising technology for carbon capture, but its application in coal-fired plants has been limited due to its low net efficiency and low economy feasibility. The utilization of pressurized oxy-combustion (POC) in coal-fired plants is known to be an effective means to improve the net efficiency. In addition to POC technology, the emerging technology of replacing steam cycle in coal-fired power plants with supercritical CO₂ (sCO₂) cycle in recent years may also be a revolutionary technology to improve the net efficiency. This paper presents a bold idea: coupling the staged pressurized oxy-combustion (SPOC) with sCO₂ cycle, with the expectation to get a new system with higher net efficiency and economic benefits. To validate this idea, a series of works are carried out on the novel system, including simulation, thermodynamic evaluation, and economic analysis. A complete SPOC coupled with sCO₂ cycle system with air separation and carbon capture is established and simulated by Aspen Plus. The simulation results indicate that the generation efficiency of the new system is improved by 3.28% (LHV) compared with an atmospheric oxy-combustion system. On this basis, the thermodynamic analysis of the system was performed to evaluate the thermodynamic performance of the system and get an improvement solution, which can increase the net efficiency by 3.58% Finally, the levelized cost of electricity (LCOE) is used to evaluate the economy feasibility of the improved system, and the calculating result is $77.71/MWh, which is lower than that of the 660-MW conventional steam cycle system. The above work demonstrates the advantages of the new system in terms of efficiency and economy feasibility, providing a new direction for the commercial application of oxy-combustion.