Process simulation of Chemical Looping Combustion using ASPEN plus for a mixture of biomass and coal with various oxygen carriers

Abstract

Chemical Looping Combustion (CLC) is an emerging technology that has shown great promise for capture of almost pure CO2 in combustion of fossil fuels in power plants. In this paper, the CLC process is modeled in ASPEN Plus and then validated using experimental data from combustion of three types of biomass as fuel, and Hematite (Fe2O3) as an oxygen carrier (OC). Three types of biomass used in the simulation are pine sawdust, almond shells, and olive stones. The effect of the fuel reactor temperature on gas concentrations (namely CO2, CO, H2, and CH4) in the fuel reactor, and the carbon capture efficiency are examined. It is found that all three biomass types have very high carbon capture efficiencies, with pine sawdust and almond shell reaching nearly 100% capture efficiency when temperatures are greater than or equal to 950 °C, while olive stones reach a capture efficiency of nearly 100% at temperatures greater than 980 °C. It is also found that the CO2 concentrations in the fuel reactor vary across the three biomass types. The effect of using Mn2O3 as OC in place of Fe2O3 was also investigated. It was found that switching the oxygen carrier to Mn2O3 caused the concentrations of CO and H2 in the fuel reactor to decrease slightly, while the concentration of CO2 increased slightly. Additionally, a mixture of coal and biomass at 895 °C was used with each of the two oxygen carriers. The results show that the system using Fe2O3 had a greater power output than the one using Mn2O3, and that power output increased as the fraction of coal in the coal-biomass mixture increased.