Chemical looping combustion of blast furnace gas from the iron and steel industry

Abstract

Chemical looping combustion (CLC), an in-situ carbon capture technology, has the potential to simultaneously achieve energy utilization and CO₂ enrichment of blast furnace gas (BFG) from the iron and steel industry. The well-designed experiments in the lab-scale batch fixed bed reactor are conducted to study the influences of temperature, flow rate, and cycle number on the CLC performance of the air/oxygen blast furnace gas (ABFG/OBFG). The Cu-Fe bi-ore oxygen carriers are prepared on an industrial scale through extrusion-spheronization and hydroforming (labeled as OCM and OCC, respectively). Results indicate that H₂ achieves a conversion of >95 % at any condition, while the CO conversion is sensitive to the temperature, e.g., from 69 % to 95 % with the temperature rising from 500 to 550 °C. The condition is then optimized as 600 °C and 100 mL/min in both ABFG and OBFG CLC tests. Under optimized conditions, the CO conversion and CO₂ yield maintain beyond 95 %, and the deposited carbon selectivity is around 2 %. In the 20-cycle experiments, the combustion of BFG is gradually improved due to the activation of oxygen carrier, confirmed by the increase of specific surface area with the cycles. The two oxygen carriers demonstrate stable chemical compositions and physical structures, according to the results of XRD and SEM-EDS. The hydroforming-derived OCC exhibits a better reactivity than the extrusion-spheronization-derived OCM. This work supports the application of CLC to the energy recovery and CO₂ capture from BFG.