The steel industry is one of the most important industry sectors, but also one of the largest greenhouse gas emitters. The process gases produced in an integrated steel plant, blast furnace gas (BFG), basic oxygen furnace gas (BOFG) and coke oven gas (COG), are due to high shares of inert gas (N2) in large part energy poor but also providing a potential carbon source (CO and CO2) for the catalytic hydrogenation to methane by integration of a Power-to-Gas (PtG) plant. Furthermore, by interconnecting a biomass gasification, an additional biogenic H2 source is provided. Three possible implementation scenarios for a PtG and a biomass gasification plant, including mass and energy balances were analysed. The scenarios stipulate a direct conversion of BFG and BOFG resulting in high shares of N2 in the feed gas of the methanation. Laboratory experimental tests have shown that the methanation of BFG and BOFG is technically possible without prior separation of CO2. The methane-rich product gas can be utilised in the steel plant and substitutes for natural gas. The implementation of these renewable energy sources results in a significant reduction of CO2 emissions between 0.81 and 4.6 Mio tCO2,eq/a. However, the scenarios are significantly limited in terms of available electrolysis plant size, renewable electricity and biomass.
Enrichment of Integrated Steel Plant Process Gases with Implementation of Renewable Energy
