Integration of S-CO2 Brayton cycle and coal-fired boiler: Thermal-hydraulic analysis and design

Abstract

An integration system for 1000 MW S-CO2 connected-top-bottom power cycle with overlap utilization and coal-fired boiler is developed. The adaptive modification module is introduced to eliminate the non-convergence for S-CO2 superheater thermal calculation in the system iteration. Thermal-hydraulic performance in terms of thermal performance, cycle efficiency, heater configurations, heater areas and final parameter evenness are discussed. Firstly, the strong constraint effects of inlet and outlet parameters on superheater thermal calculation convergence are demonstrated and the adaptive modification module is established. Secondly, based on the detailed thermal-hydraulic analysis, different layouts are compared to identify the flow path way and the heat absorption of S-CO2 flow in different heating processes. The midpoint between the two peaks of heat flux is recommended as the start point for the cold fluid placement in cooling wall arrangement. Finally, a new layout is proposed to obtain the highest overall thermal-hydraulic performance, with a net power efficiency up to 47.57% and a total heater area of 316426.18 m2. The design sequences for S-CO2 coal-fired boiler heaters are recommended as well.