Impurity effects on the oxy-coal combustion power generation system

Abstract

A feasibility study has been conducted on the retrofit project of existing coal fired power station, Youngdong unit 1, to incorporate an oxy-coal combustion system. One of the critical issues for the project is the optimization of O-2 supply and CO2 sequestration facilities. Existence of impurity in the flue gas, mainly non-condensable gases and acid, requires additional work for separation and thus degrades the net plant efficiency even more. The aim of this study is to investigate the effect of impurity on the CO2 purification process and suggest possible ways to control impurity content, as a part of the conceptual design of the project. Impurity sources considered in this research are O-2 purity, excess O-2, and air ingress. Results of CO2 purity, CO2 recovery rate, and power cost obtained from the process evaluation are compared for the optimization of operation. The performance of oxy-coal combustion power generation system was evaluated in terms of CO2 concentration in the flue gas at the inlet of the CO2 purification unit. On the ground of the results, the O-2 purity and air ingress are main worsening factors to the system performance. In addition, measures to control impurity for the optimization of overall system are discussed in terms of O-2 purity selection at different CO2 purity requirements, excess O-2 ratio considering the combustion efficiency, and replacement of excess O-2 with air ingress. (c) 2012 Elsevier Ltd. All rights reserved.