Effect of Oxygen Carriers on Performance of Power Plants with Chemical Looping Combustion

AbstractThe paper pursues process based analyses on power plants employing multi-stage chemical looping combustion (CLC) technology for carbon capture using different oxygen carrying materials and fuels. The aim is to determine any specific process based advantages offered by different oxygen carriers. CLC is an innovative combustion concept, which offers a potentially attractive option to capture CO2 with a significantly lower energy penalty than other existing carbon-capture technologies. In the CLC process, the combustion of fuel is split into two separate reactions carried out in two separate reactors: an oxidation reaction and a reduction reaction, by introducing a suitable metal oxide as an oxygen-carrier that circulates between the two reactors. This study investigates the viability of nickel, copper and iron as oxygen carriers using them with natural and synthesis gas fuels. It was conducted by developing an Aspen Plus based model, which employed the conservative principles of mass and energy. Equilibrium based reactor models with no oxygen-carrier (OC) deactivation were assumed. The choice of oxygen carrier and its effect on key operating parameters such as air, fuel and oxygen carrier mass flow rates, operating pressure, and the waste heat recovery were investigated for each fuel. For all OCs, the maximum temperatures were observed at stoichiometric OC mass flow rates for the given fuel supply. The peak reduction reactor temperatures were obtained with copper OC, which may require inerts or other temperature reduction strategies to avoid thermal deterioration. Maximum thermal efficiencies were observed for iron and nickel OCs. However, iron requires considerably larger OC mass flow rates compared to nickel and copper