Partial load operation characteristics of supercritical CO2 coal-fired power generation system

Abstract

The steady-state model of a 300 MW supercritical CO2 coal-fired power generation system (SCPGS) is established to investigate its partial load characteristics. The SCPGS model predicts the reduction of reheat CO2 temperature in partial load operation, which is not reflected from the traditional black box model due to its simplification of heat transfer processes in the boiler. Effects of the burner angle and split ratios on regulating the reheat temperature is simulated. It is found that increasing the burner angle can effectively raise the reheat temperature and system efficiency. However, the higher furnace outlet temperature makes the heating surface easy to coke and slag. Changing the split ratios can also regulate the reheat temperature while the system efficiency is reduced. Accordingly, a comprehensive control strategy is proposed: at 100%–85 % load ratio, no regulation is applied; at 85%–45 % load ratio, the burner angle is gradually adjusted upward; at 45%–20 % load ratio, the burner angle is set to 30o and the split ratios are changed in the order of xEAP, xH4a, and xC2. This control strategy enables the SCPGS to achieve wide load regulation efficiently and safely and can provide guidance for the dynamic regulation of the SCPGS with variable load operation.