Application of Carbon Dioxide Capture Technology from Blast Furnace Gas in Foreign Steel Enterprises

1.Technical Background

The production process of the traditional steel industry is heavily dependent on fossil fuels such as coal and coke. Therefore, the steel industry has become a major energy consumer and CO2 emitter second only to the power industry. Statistics from the International Energy Agency show that CO2 emissions from the manufacturing industry account for about 40% of the world's total CO2 emissions, of which the steel industry accounts for about 27% of CO2 emissions from the manufacturing industry. The energy consumption of the ironmaking system accounts for more than 70% of the total energy consumption of steel production, and CO2 emissions account for about 80% of the entire steel production process, which is a key link in energy conservation and emission reduction in the steel industry. Adhering to the operation of blast furnace fine materials, optimizing wind temperature, oxygen enrichment and other adjustment methods, and promoting low fuel ratio operation are certainly one of the important measures for the ironmaking system to reduce energy consumption and reduce CO2 emissions, but the emission reduction effect is very limited. The use of carbon capture combined with low-carbon ironmaking technology to reduce direct CO2 emissions will gradually become an effective measure to solve carbon emissions in the steel industry.

2.Carbon dioxidecapture process

There are currently three main CO₂ capture processes, including pre-combustion capture, combustion process capture and post-combustion capture. Among them, post-combustion capture is the only process that has been industrialized. The post-combustion CO₂ capture devices that have been put into production worldwide include Norway's 3 million tons of CO₂ annual processing device and Canada's 1 million tons/year CO₂ capture device. The core of these technologies is gas separation. Post-combustion CO₂ capture is the separation of CO₂ and N₂, pre-combustion capture is the separation of CO₂ and H₂, and combustion process capture is the separation of O₂ in the air. The separation of gases in all technologies needs to be carried out under certain temperature, pressure and CO₂ partial pressure conditions. The key to selecting the capture process is to achieve the lowest energy consumption and capture cost.

3. Application of carbon dioxidecapture in foreign steel enterprises

Physical adsorption method for separating CO₂ from blast furnace gas by JFE Steel of Japan. JFE Steel Corporation of Japan has established a small CO₂ capture test facility at its Fukuyama plant, with a processing capacity of 3t/d and coal gas of about 300m³/h. It uses physical adsorption technology to separate CO₂ from blast furnace gas. This project is one of the sub-projects of Japan's "Cold Earth 50" (COURSE50) plan. After pressurization and cooling, the blast furnace gas flows through the dehumidification tower in turn to remove moisture and sulfide from the gas, and the clean gas enters the PSA core processing unit. The unit is divided into two sections, the first section is CO₂-PSA, and the second section is CO-PSA, which separates CO₂ and CO from the gas respectively. The separated and recovered CO gas is a high calorific value gas fuel that can be used in sintering, hot blast furnaces and steel rolling processes.