Autothermal operation of a pressurized Gas Switching Combustion with ilmenite ore

This paper presents further experimental testing of the Gas Switching Combustion (GSC) concept where ilmenite is used as oxygen carrier and CO as fuel for integration into an IGCC plant. In contrast to conventional chemical looping combustion (CLC), GSC keeps the oxygen carrier in a single fluidized bed reactor where it is alternately exposed to fuel and air. This reactor configuration greatly simplifies scale-up under the pressurized conditions required for competitive efficiency in gas-fuelled chemical looping applications. Autothermal operation of the lab-scale GSC reactor was achieved for ilmenite and a synthetic Ni-based oxygen carrier. Even though the synthetic oxygen carrier clearly outperformed the ilmenite ore in terms of reactivity and oxygen transport capacity, ilmenite performance was found to be good enough for efficient application in GSC-IGCC power plants. The experiments also suggest that ilmenite kinetics is not negatively affected by increases in pressure as has been reported for other synthetic oxygen carriers, thereby further increasing the attractiveness of ilmenite as an oxygen carrier for the high-pressure GSC-IGCC application.