A novel slag carbon arrestor process for energy recovery in steelmaking industry

A novel slag carbon arrestor process (SCAP) was proposed to improve the heat recovery in energy-intensive steelmaking process, which typically has a low heat recovery. The proposed SCAP process introduces a tar reformer to utilise the slag - a by-product from steelmaking process - as the catalyst to convert coke oven gas and tar into hydrogen-enriched fuel gas. This is achieved by making use of the valuable carbon and/or energy contained in the coke oven gas, which otherwise being wasted, to assist in tar reforming and produce hydrogen-enriched gas. Such concept is expected to reduce the undesired tar formation in steelmaking process along with improved heat recovery efficiency and higher quality coke oven gas production. Both simulation and experimental studies on the slag carbon arrestor process were performed. The preliminary thermodynamic analysis carried out using Aspen Plus v8.4 indicates that with the tar reformer the energy content of coke oven gas was found increased from ~ 34.6 MJ/kg to ~ 37.7 MJ/kg (or by 9%). Also, with the utilisation of carbon deposition on the slag, a reduction of up to 12.8% coke usage in the steelmaking process can be achieved. This corresponds to an energy saving of 4% and a carbon emission reduction of 5.7% compared with the conventional steelmaking process. Preliminary experimental TGA-FTIR investigations revealed a reduction in the aromatic and aliphatic hydrocarbon groups and an increase in the production of CO₂ and CO, attributed to the tar cracking abilities of slag.