Research On Integrated Gasification Combined Cycle System Coupled With Chemical Looping Combustion To Capture CO₂

The utilization of fossil fuels releases significant quantities of CO2,leading to climate crises such as global warming,which poses a serious threat to the sustainable development of mankind.Capturing and storing carbon dioxide at sources of CO2 emissions such as coal-fired thermal power plants is one of the important means to achieve large-scale CO2 emission reduction.The Integrated gasification combined cycle(IGCC)is an advanced,environmentally friendly coal-fired power generation system that also has significant advantages in CO2 emission reduction.Based on the advantages of IGCC and chemical looping combustion(CLC),this paper uses Aspen Plus software to build a benchmark IGCC system and an IGCC system coupled with chemical looping combustion to capture CO2,and studies the operating characteristics of the system.Sensitivity analysis was performed on key parameters affecting the IGCC system.Based on the coal types selected in this paper,the optimal oxygen-to-coal ratio of coal gasifier and the ratio of water-to-coal were 0.57 and 0.06,respectively.And the optimal gasification temperature of a coal gasifier is 1350℃.The sensitivity analysis of the parameters of the IGCC system for CO2 capture by chemical looping combustion using Ni-based and Fe-based oxygen carriers was analyzed.The effects of temperature and pressure and inlet flow strand changes on system performance of fuel reactor and air reactor were analyzed,and the best parameters of reactor and flow strands were obtained.The thermodynamic properties of the IGCC system coupled with chemical looping combustion to capture CO2 were analyzed,and the performance of different systems was compared from the thermodynamic perspective.The results showed that the energy efficiency of the benchmark IGCC system was 44.52%and 41.10%.The energy efficiency of the IGCC-CLC system with Ni as oxygen carrier was 41.41%,the exergy efficiency was 38.23%,and the carbon capture efficiency was 98.93%.The energy efficiency of the IGCC-CLC system with Fe as oxygen carrier was 39.02%,the exergy efficiency was 36.02%.and the carbon capture efficiency was 92.71%.The efficiency of the IGCC-CLC system with Ni as oxygen carrier and the IGCC-CLC system with Fe as oxygen carrier decreased,and the energy efficiency was reduced by 3.11 and 5.50 percentage points,and the exergy efficiency decreased by 2.87 and 5.08 percentage points,respectively.The performance of IGCC-CLC system is superior to the IGCC system using traditional CO2 capture methods.There is underutilized chemical energy in the exhaust gas of the Fe-based IGCC-CLC system,which causes the reduction of carbon capture rate,energy efficiency and exergy efficiency of the system.Most of the exergy losses in IGCC-CLC are caused by chemical looping combustion units and coal gasification units,which account for 70%of the total exergy losses.The IGCC system coupled with chemical looping combustion to capture CO2 proposed in this paper has high energy efficiency and exergy efficiency,as well as high carbon capture efficiency.It can provide ideas for clean coal technology and help achieve carbon reduction goals.