TECHNOLOGY

Chemical absorption is a technology to capture CO₂ from blast furnace gas (BFG): an alkaline aqueous solution, or absorbent, such as amine, selectively absorbs CO₂ when contacting blast furnace gas (BFG) containing CO₂ in an absorption tower, and then the CO₂-laden absorbent releases CO₂ after heating in a regeneration tower.
Development of chemical absorption, though suitable for capturing large amount of CO₂ from gases at ordinary pressure, has just been launched aiming at applying to steelmaking process, and several technical issues need to be solved. This project will address the following technical issues, incorporating an evaluation pilot plant with the capacity of approximately 30t-CO₂/day into a real steelmaking plant:

• Reduction of energy consumption – development of new absorbent solutions and effective utilization of energies from steelmaking processes.
• Quantification of effects of CO₂ capturing technologies on steelmaking processes

The developed absorbents have been commercialized for industrial application as by NIPPON STEEL ENGINEERING CO., LTD.; Energy-Saving CO₂ Absorption Process (ESCAP™).

Development of novel chemical absorbents with the aid of experimental and computational methods

New chemical absorbents, by which a CO₂ capture system can be operated with lower CO₂ capture energy, are developed by means of joint experimental and computational methods such as quantum chemistry and statistical data processing.

Development of Physical Adsorption Technology

Physical adsorption method is a technology that can separate and recover carbon dioxide with low energy consumption, though requiring a simple system configuration. With the physical adsorption method, adsorbents, first of all, selectively adsorb CO₂ with the help of the van der Waals force working between the molecules of fluid and the surface of the adsorbents, and then release the adsorbed CO₂ under a reduced pressure, consequently allowing CO₂ capture – separation and recovery – with high purity at high recovery rates. This is the first attempt in Japan to apply this technology to a processing on a very large scale, i.e., capture – separation and recovery – of CO₂ from blast furnace gas.

By selecting the most suitable CO₂ adsorbent in the laboratory test, the target recovery rate was obtained.

In this project, an evaluation plant with a capacity of 3 t-CO₂/day was constructed in the steelworks. Efforts were made to further reduce energy consumption and to develop a scale-up process.