Thermodynamic analysis of hydrogen production from raw coke oven gas via steam reforming

Abstract

The steam reforming processes of raw coke oven gas (RCOG) for hydrogen production without and with CO2 adsorption were studied via the thermodynamic analysis. Ordinary pressure (1 bar) was found as the best reaction pressure for RCOG steam reforming. The hydrogen yield increased with the increases in temperature and S/RCOG ratio and then flatted out around 160 mol per 100 mol RCOG at the temperature above 700 °C and S/RCOG ratio above 0.8, yet with hydrogen concentration of just about 70 %. After the addition of CaO as CO2 sorbent, the hydrogen yields increased on the whole as the CaO/C ratio and S/RCOG ratio rose, and the temperature range with the hydrogen yield around 160 mol and even higher was widened and moved to low temperature. The optimal conditions of sorption-enhanced RCOG steam reforming for hydrogen production were S/RCOG ratio above 0.8, CaO/C ratio above 2.0 and the temperature from 550 to 700 °C, with the hydrogen yield and concentration reaching around 160 mol and over 90 %, respectively.