Key issues and innovative double-tangential circular boiler configurations for the 1000 MW coal-fired supercritical carbon dioxide power plant

Abstract

When supercritical carbon dioxide (S–CO2) Brayton cycle is introduced into conventional coal-fired power plant, there exists the problems in S–CO2 boiler configurations due to the working medium physical properties’ change. This paper is taking a typical 1000 MW single reheat double-tangential circular boiler as example and investigations focus on the key issues of S–CO2 power plant with traditional boiler configuration from the thermodynamic system, combustion and heat transfer in the furnace, flow and heat transfer in tube. The results show that the studied traditional boiler configuration does not adapt for the 1000 MW S–CO2 coal-fired single reheat power plant for the mismatch heat duty. The effects of boiler size and flue gas recirculation ratio on the heat duty distribution and boiler performance are analyzed. Decreasing the boiler heat duty singly will have a negative impact on boiler performance. The newly developed “partial expansion at the upper zone + double furnace + symmetry flow mode” boiler configurations for the S–CO2 Brayton cycle are presented in order to coordinate the heat duty distribution and boiler performance. The overall net efficiency of the innovative 1000 MW single reheat S–CO2 power plant is up to 48.26%, higher ∼4% than the same-grade traditional steam power plant.