Study On LNG Oxy-fuel Combustion Power System Performance Based On Exergy And Exergoeconomic Analysis Methods

With the increasing demand for energy,it is imperative to achieve energy conservation and CO₂ emission reduction.As one of the most industrializable carbon capture methods,oxy-fuel combustion systems can effectively offset the energy penalty from carbon capture by combining LNG gasification process and improve the system power production efficiency.However,since high-temperature combustion and carbon capture processes require significant cost investment,developing an evaluation system to assess the economic feasibility of oxy-fuel combustion power plant is urgent.In this paper,O₂/CO₂combustion system,O₂/water combustion system and O₂/steam combustion system are simulated by Aspen Plus software.With the utilization of exergy and exgoeconomic analysis methods,the calculation models of system exergy destruction and economic cost are established,the energy consumption and economy are evaluated,the position of exergy destruction and cost rate are located,and the improvement potential of energy efficiency and economy is quantified.Based on the analysis results,the effects of different types of diluent on the system energy consumption,economy,and improving potential are discussed in detail.According to the results of discussion,the oxy-fuel system with the highest energy saving potential is improved from the perspective of component exergy destruction correlation and sensitive analysis.The results of this research show that the O₂/CO₂ combustion system operates with the highest exergy efficiency and energy savings potential.The exergy efficiency of O₂/CO₂combustion system is 51.12%,and system exergy destruction value is 509.77 MW,of which the avoidable part accounts for 19.97%.Considering system economy,the O₂/water combustion system shows the remarkable highest economic feasibility.The total cost value of O₂/water combustion system is about 1.86?10⁵$/h,which is much lower than the value of 9.87?10⁵$/h in O₂/CO₂ combustion system and the value of 3.47?10⁵$/h in O₂/steam combustion.Besides,over 53.66%of the total cost rate in O₂/water combustion is avoidable,which is much higher than that in O₂/CO₂ combustion system and O₂/steam combustion system(33.98%and 33.61%).The improvement of O₂/CO₂combustion system reveals that improving other components has a positive influence on raising the net efficiency of the combustor,and the exergy destruction of heat recovery steam generator can be decreased over 88.17 MW by improving the flue gas treatment unit.Furthermore,decreasing the combustion temperature to 1385?or increasing the outlet temperature of the natural gas and flue gas heat exchanger device to 38?,the system exergy efficiency can be promoted by 0.34%and 0.43%respectively.