Performance of sCO2 coal-fired power plants at various power capacities

Abstract

Herein, the effect of the power capacity, Wnet, on the performance of supercritical carbon dioxide (sCO2) coal-fired power plants is investigated, with Wnet in the range of (100–1000) MWe. A comprehensive model was established wherein the sCO2 cycle was coupled with the models of various components. For the sCO2 boiler, the total thermal load was assigned to various heaters, and the pressure drop in each heater was calculated. Owing to the strong penalty effect of the pressure drop, both total flow mode (TFM) and partial flow mode (PFM) were applied to the sCO2 boiler. A fluid network integrating the recuperator units was established for heat recovery in the system. A thermal-hydraulic model was proposed for a single unit and an integration package. Various losses were considered in the prediction of the efficiencies of axial flow turbines and compressors. The thermal efficiency increases, attains a maximum, and then decreases with increase of Wnet. This parabolic distribution results from the tradeoff between the decreased efficiency owing to pressure drops in the heat exchangers and the increased efficiency of the turbomachinery. The maximum thermal efficiency occurred at Wnet of 300 MWe and 200 MWe when using the PFM and TFM, respectively. Based on the results, PFM is found to eliminate the penalty effect of pressure drops. Our study provides guidelines for the design and operation of sCO2 coal-fired power plants.