Thermoeconomic cost analysis of a 600 MWe oxy-combustion pulverized-coal-fired power plant

Abstract

Oxy-combustion technology, through adding a cryogenic air separation unit process and a flue gas treatment unit process to a conventional combustion process, has been rapidly developed because it is considered as a feasible choice to capture CO2 from power plants for sequestration. To reach a comprehensive understanding of the thermodynamic and economic characteristics of the oxy-combustion process, a detailed thermoeconomic cost analysis of a 600MWe oxy-combustion pulverized-coal-fired power plant was carried out. Based on the detailed results of exergy analysis and the latest data of investment cost, the results of exergy cost and thermoeconomic cost were obtained. It is found that, in comparison to the corresponding conventional supercritical plant with the same gross output (600MWe), the additional power consumption in the oxy-combustion system increases the unit exergy costs (or unit thermoeconomic costs) of products for about 10%. On the other hand, the additional monetary cost, including investment cost, interest, and operation and maintenance cost, in the oxy-combustion system increases the unit thermoeconomic costs of products for nearly another 10%. The relation between the unit thermoeconomic cost change and the unit exergy cost change in the oxy-combustion system comparing to the conventional system was established. Moreover, in this paper, a new decomposition method for exergy cost was proposed to explore the formation mechanism of the exergy cost, furthermore, the thermoeconomic cost. The unit exergy cost was decomposed into three parts: fuel, exergy destruction, and negentropy. Meanwhile, the reasonable unit exergy costs of exergy destructions happened in the system can be defined. It is found that the exergy destruction part is the most important factor that affects the unit exergy costs of products for these components in the same model (such as the boiler model).