Relevance of the coal rank on the performance of the in situ gasification chemical-looping combustion

Abstract

In this work the CLC process for solid fuels using ilmenite as oxygen carrier was evaluated in a continuous CLC unit. In this process, gasification of solid fuel happens in the fuel reactor which is fluidized by a gasifying agent, i.e., H2O. This process has been referred as in situ gasification CLC, iG-CLC. The feasibility of using fuels ranging from lignite to anthracite and the effect of the coal rank on the process performance was evaluated. The carbon capture efficiency followed the trend of the coal rank, as it was higher for lignite, then for the bituminous coals and it was lower for anthracite. Special attention was put on the combustion of the volatile matter of the different fuels. In all cases oxygen demands lower than 10% were found; for anthracite the oxygen demand values were 3.5% because of the lower volatile content of this fuel. A temperature increase was proven to be advantageous to reach high carbon capture and combustion efficiencies for all the fuels tested. Also, the feasibility of using H2O:CO2 mixtures as gasification agent with each type of fuel was also assessed and it was seen that in case of bituminous coals and lignite some of H2O can be replaced by CO2.