Production of high-quality combustible gas: The green and efficient utilization of inferior dust removal ash and high-temperature flue gas in converters

Abstract This study proposes a new process to produce high-quality combustible gas by spraying dust removal ash (DRA) into the high-temperature flue gas of a converter to efficiently utilize inferior DRA from coking plants and improve environmental protection. This new process not only efficiently utilizes the DRA resource but also improves the quality of the combustible flue gas. Further, this study systematically verified the feasibility of this new process using FactSage 6.1 software; SEM/energy-dispersive X-ray (EDX), X-ray powder diffraction (XRD), and Brunauer–Emmett–Teller (BET) methods; thermogravimetric and settling furnace experiments; industrial tests; and other experimental methods. The results reveal that DRA contained relatively high amounts of minerals and exhibited a large specific surface area. When compared with demineralized DRA (DDRA), DRA produced combustible gases, such as CO, H2, and CH4, and exhibited a decreased rate of CO2 production. High temperatures and small particle sizes can promote gasification reaction and improve the quality of the combustible gas. Industrial tests revealed that the injection rate increased from 0 to 25 kg min−1, CO content increased from 51.5% to 58.9%, H2 content increased from 1.1% to 2.3%, and CO2 content decreased from 22.3% to 17.5% at an injection depth of 400 mm. Thus, the reaction of DRA and high-temperature flue gas ensures the green utilization of a solid waste resource and improves the quality of high-temperature flue gas in converters, thereby providing economic benefits. The proposed process provides novel insight into the utilization of large amounts of industrial waste.