An evaluation of hydrogen production from the perspective of using blast furnace gas and coke oven gas as feedstocks

Blast furnace (BF) is a large-scale reactor for producing hot metal where coke and coal are consumed as reducing agent and fuel, respectively. As a result, a large amount of CO₂ is liberated into the atmosphere. The blast furnace gas (BFG) and coke oven gas (COG) from the ironmaking process can be used for H₂ production in association with carbon capture and storage (CCS), thereby reducing CO₂ emissions. In this study thermodynamic analyses are performed to evaluate the feasibility of H ₂ production from BFG and COG. Through the water gas shift reaction (WGSR) of BFG, almost all CO contained in BFG can be converted for H₂ production if the steam/CO (S/C) ratio is no less than unity and the temperature is at 200 °C, regardless of whether CO₂ is captured or not. The maximum H₂ production from WGSR is around 0.21 Nm ³ (Nm³ BFG)^-1. Regarding H₂ production from COG, a two-stage reaction of partial oxidation (POX) followed by WGSR is carried out. It is found the proper conditions for syngas formation from the POX of COG is at the oxygen/fuel (O/F) ratio of 0.5 and the temperature range of 1000-1750 °C where the maximum syngas yield is 2.83 mol (mol hydrocarbons)^-1. When WGSR is subsequently applied, the maximum H₂ production from the two-stage reaction can reach 0.83 Nm ³ (Nm³ COG)^-1.