CO2 Capture and Desulfurization in Chemical Looping Combustion of Coal with a CaSO4 Oxygen Carrier

Chemical looping combustion (CLC) of coal along with desulfurization was investigated in a fixed-bed reactor with anhydrite as oxygen carrier and CaO and CaCO3 as desulfurizers, regarding the influence of temperature, pressure, mass ratio of coal to CaSO4, and Ca/S ratio. CO2 concentration and fuel conversion increased with higher temperature and pressure but decreased with higher mass ratios of coal to CaSO4. Approximately 94% outlet CO2 concentration and 83% carbon conversion could be achieved under optimum operating conditions. Desulfurization tests proved the higher desulfurization efficiencies of both CaO and CaCO3 at elevated temperatures and pressures. CaO performed better than CaCO3, and an optimum value of Ca/S ratio existed for CaO. These findings demonstrate a good performance of anhydrite as oxygen carrier and the promising prospects of desulfurization in CLC of coal.