Multi-criteria assessment of a new energy-saving and environmentally-friendly scheme for natural gas-fired power plants

Abstract

Recently, natural gas-fired power plants have received wide attention for their environmental advantages. However, high-temperature waste gas causes a quantity of heat loss, and a large amount of carbon dioxide emissions exacerbate the greenhouse effect. In order to efficiently utilize the waste heat of flue gas and reduce the carbon dioxide emissions from power plants, a cascade system which combines waste heat recovery technologies, including the supercritical carbon dioxide (SCO2) cycle and trilateral organic cycle (TOC), with carbon dioxide capture device is proposed. After validating the accuracy of thermodynamic model, the optimum working fluid for the trilateral organic cycle is selected and some main factors affecting the thermodynamic performance are analyzed in detail. Finally, to test the feasibility of the design, this paper optimizes the economy performance of the cascade system and the amount of captured CO2. The results show that the maximum net output power, carbon dioxide capture and payback period of the system are 157.1 MW, 96.49 ton/h and 4.125 years. Moreover, compared with original power plant design, the net plant efficiency of the cascade system has a significantly increasing of 23.6%. Hence, the new scheme proposed in this paper is a feasible method to achieve the aim of energy conservation and emission reduction.