Advanced exergy and exergoeconomic analyses to evaluate the economy of LNG oxy-fuel combined cycle power plant

Abstract

Oxy-fuel combustion has attracted wide attention since it is thought to be an advanced technology for CO2 capture from the power generation plant on a large scale. An oxy-fuel combustion system is proposed to raise system energy efficiency utilizing cold energy from liquefied natural gas (LNG). The quantitative research on the exergy consumption, economic feasibility, and optimization strategies of the LNG oxy-fuel combustion system is conducted by advanced exergetic and exergoeconomic analyses. The results show the oxy-fuel system has an exergy efficiency of 46.83 %. The exergy destruction of the oxy-fuel system is 445.51 MW, of which the avoidable part accounts for 81.68 %. In terms of economic feasibility, the oxy-fuel system costs approximately 4.44 × 106$/h, which is considerably higher than the value of 1.99 × 106$/h in the air system. Moreover, more than 78.21 % of the cost in the oxy-fuel system is avoidable, 36.05 % higher than that of the air system. The work discovers that in the combustor of the oxy-fuel system, the improvement of the flue gas treatment unit (FGU) has a significant impact on promoting its net efficiency, and increasing its investment cost rate is not an economic limitation to save the system economy. The study is crucial for the application of oxy-fuel combustion electricity generation technologies.