Dry reforming of steelworks off-gases in a pilot plant integrated into a steel mill: influence of operating parameters

Abstract

A novel process is applied in a pilot plant integrated within a steel mill in Saarland, Germany, in which the greenhouse gases CO₂ and CH₄ are converted into synthesis gas, a mixture of H₂ and CO, by homogeneous dry reforming. The process is based on heating a gas mixture of coke oven gas (COG) and blast furnace gas (BFG) to high temperatures in a regenerative heat exchanger, similar to the existing hot blast stoves used to heat the hot blast blown into the blast furnace. The resulting synthesis gas can be injected into the blast furnace at the level of the shaft and/or tuyere, reducing coke consumption in iron production, potentially leading to a reduction in global CO₂ emissions of about 0.5%. After commissioning, the cyclic operating pilot plant was used to study a wide variation of operating parameters. At a maximum local peak temperature of over 1721 K during the synthesis gas production phase, an average conversion of about 97% for CH₄ and over 94% for CO₂ was achieved, which is close to the thermodynamic equilibrium of over 99% and about 98%, respectively. The scale-up process is accomplished by modeling and numerical simulation. The measured data obtained from the pilot plant agree well with the numerical simulations using a detailed elementary-step reaction mechanism.