One dimensional design of small capacity supercritical CO2 coal fired power generation system and analysis of regenerator compactness

Supercritical CO2(S-CO2)cycle is expected to be the next generation power cycle for electricity generation because of its high efficiency，compactness and flexibility. In this study，a tri⁃compression with last⁃stage partial com⁃ pression S-CO2 cycle was applied to a 20 MW S-CO2 coal⁃fired power generation system，and the one⁃dimensional de⁃ signs of components were conducted. It is shown that the size of turbine is significant smaller than that of the tradition⁃ al steam turbine，thus it has obvious competitiveness compared with the water steam unit. Based on the volume change law of boilers with different capacities，it is reasonably inferred that the volume of S-CO2 boiler is larger than the steam boiler due to the smaller heat transfer coefficient of the CO2 in the boiler. The regeneration system based on the prin⁃ ted circuit heat exchanger covers a large area with a volume around 18.95 m3，which is far more than the existing re⁃ generation system of the water steam unit and the problem is significant. Therefore， this study further explored the characteristics of the regeneration system from the perspective of the heat transfer of the regeneration， discussed the difficulties faced by the existing technology，and found that there is a strong constraint relationship be⁃ tween the cycle thermal efficiency and the volume of the regeneration system，and then conducted an economic analysis of the regeneration system. After considering the infrastructure and labor costs，the investment cost of the regeneration system is about 93 474 700 yuan，which is a high initial investment cost. It was also found that the printed circuit heat exchanger has limited potential to reduce the size of the regeneration system， thus new heat exchanger types still need to be developed to increase the magnitude in heat transfer coefficient. Finally，to address the size problem of the regeneration system，this study proposed an integrated arrangement scheme for the S-CO2 coal⁃fired power gen⁃ eration system， which achieves the overall compactness of the system by optimizing the space arrangement. Currently，the demonstration of S - CO2 coal⁃fired power plants is promoted in China， and this research provides some novel technical ideas for the demonstration system.