Thermodynamic analysis of integrated adiabatic chemical looping combustion and supercritical CO₂ cycle

In this study, an integrated adiabatic operated chemical looping combustion and supercritical CO₂ Brayton cycle using biomass as feedstock was studied based on the thermodynamic analysis. Based on comparisons of species and adiabatic flame temperature in the product gas, it was found that high air and oxygen carrier flow rates are required in adiabatic chemical looping combustion for obtaining the results from the conventional combustion under adiabatic operation. Using the product gas from the fuel reactor and flue gas from the air reactor as heat sources for the simple recuperated supercritical CO₂ Brayton cycle, it is found that the cycle efficiency increases with increased turbine inlet temperature and decreased condenser exit temperature under various compressor discharge pressures. The overall thermal efficiency of the integrated system, defined as the ratio of total net work of the power cycle to the higher heating value of biomass, depends on the CO₂ mass flow rates in the power cycles and also increases with increased compressor discharged pressures. The maximum cycle and overall thermal efficiencies are found to be 51% and 21%, respectively.