Chemical Looping with Oxygen Uncoupling of Biomass and Coal: Scaling-Up to 50 kWth Using a Copper-Based Oxygen Carrier

Chemical looping with oxygen uncoupling (CLOU) is an advanced CO2 capture technology where an oxygen carrier supplies the gaseous oxygen required for combustion. The technology has experienced a significant development degree in the most recent decades, up to TRL 4. This study presents results that further prove the viability of this technology to TRL 5 in a continuous CLC unit with two interconnected circulating fluidized beds acting as fuel and air reactors. The oxygen carrier used in the experiments was a magnetic copper-based oxygen carrier denoted as Cu30MnFe. It was used in the combustion of three types of biomass and a bituminous coal (Taldinsky coal). The effects on char conversion, CO2 capture efficiency, and total oxygen demand of different parameters such as excess air ratio, fuel reactor temperature, residence time in fuel reactor, gas velocity in the carbon stripper, solid circulation rate, and solid inventory in fuel reactor were investigated. CO2 capture efficiency of 93% was achieved at 886 °C with pine sawdust combustion, while the total oxygen demand was 4.6%. In the experiments with bituminous coal, the effectiveness of the carbon stripper in improving the CO2 capture efficiency was demonstrated. During the highest load of coal, low total oxygen demands were achieved even at temperatures below 900 °C.