Sorption-enhanced reforming of raw COG and its adaptability to hydrogen metallurgy: Thermodynamic analysis

Abstract

In order to solve the problem of hydrogen shortage in the popularization of hydrogen metallurgy, the steam reforming of raw coke oven gas (raw COG) and its adaptability in reducing sinter ore were studied thermodynamically in this paper. Compared to the self-reforming and steam reforming, the maximum of hydrogen yield in the sorption-enhanced reforming process can go up to 1.54 mol/mol raw COG and move the reforming temperature from above 900 °C to the zone between 500 °C and 600 °C. According to the concentrations of reducing gas components to be used in the hydrogen metallurgy, the reformed gases from raw COG was merged and rearranged, and then six kinds of reformed gases were selected as typical gases for the subsequent reduction of sinter ore. The reformed gas can effectively reduce the formation of the intermediate product and improve the yield of iron, and the temperature requirement of the reduction process was reduced. Finally, based on a comprehensive analysis of the raw material consumption for the reforming and reduction processes, the optimal reforming condition that reforming temperature is 500 °C, S/C (the molar ratio of steam to carbon) is 3.6 and CaO/C (the molar ratio of CaO to carbon) is 2.0 and the optimal reduction condition that reduction temperature is 900 °C–1100 °C, R/O ratio is 2.0 are obtained. The matched optimization leads to a reduction in both RCOG and sinter consumptions, significantly reducing the consumption of raw materials and improving the economy of the hydrogen metallurgical process.