(617hv) Combined Process for Hydrogen Production from Coke Oven Gas (COG)

Steel industry has been clearly classified as a mass CO₂ emission sector because approximately 2 ton CO₂ per 1 ton steel is produced. Almost carbon dioxide in the steel industry are emitted from pig iron making process, because C (Carbon) is employed for a reducing agent of iron ore (2Fe₂O₃+3C à 4Fe + 3CO₂) and intensive energy should be provided to make molten iron.

A blast furnace is the typical facility for producing pig iron and moving bed reactor operated at high temperature. Sintered iron ore and coke (carbon resource) are fed to the top of blast furnace for producing pig iron and coke is used for energy source and reducing agent. The reducing reaction of iron ore is divided into direct reduction and indirection reduction. In case of direct reduction, coke and iron ore are directly converted into molten pig iron with solid-solid state reaction at high temperature. Therefore, direct reduction between iron ore and coke is usually occurred at the bottom part of the blast furnace. Alternatively, carbon monoxide (CO) is basically used for reducing iron ore into other iron oxide form during the indirect reduction. As a result of using coke as energy source and reducing agent, mass carbon dioxide should be produced in the steel industry.

Due to operating ETS (Emission Trading Scheme) in South Korea, steel making company has been allocated challengeable CO₂ emission reductions. To response to challengeable CO₂ emission reductions, energy saving and hydrogen reduction of iron ore have an attention as key technologies for reducing greenhouse in steel industry. Especially, CO₂ emissions will be reduced by substituting carbon with hydrogen as the reducing agent, because the product for hydrogen reduction of iron ore is H₂O. For adopting hydrogen reduction of iron ore in a steel industry, large amount of hydrogen should be provided to hydrogen reduction process.

COG (Coke Oven Gas) which is one of by-product gases is mainly consisted of 25% CH4, 55% H2, and 7% CO in steel mill. Because more than 50% hydrogen is included in COG, COG has been considered as an attractive hydrogen resource. A large amount of hydrogen can commerically be produced with H2-PSA, CH4(in COG)-H2O reforming, water gas shift (WGS) process. In this study, hydrogen production technologies using COG will be introduced.