Abstract
Supercritical CO2 (S-CO2) Brayton cycle perceives the advantages of high cycle efficiency and compact turbine machinery. In certain temperature ranges, its cycle efficiency can be higher than that of a steam Rankine cycle. However, process synthesis for an S-CO2 cycle operating at an ultra-supercritical steam cycle level, aiming at large-scale power generation, is still lacking, and systems analysis and comparison between these cycles are needed. In this paper, a double reheat recompression S-CO2 Brayton cycle model for a coal-fired power plant is presented, with which various options of mass and energy integration amongst the process can be studied and optimized. Thermodynamic analysis of various process integration options is carried out focusing on impacts on key cycle parameters. Process synthesis results show that when turbine inlet temperature reaches 600 °C, thermal efficiency of the S-CO2 cycle can reach 52.5 %, 4.5 percentage points higher than an ultra-supercritical steam cycle operating at the same level.
