(374g) Performance Analysis of a Multi-Bed PSA Process Using Silica-Based Adsorbents for CO2 Capture from Off-Gas in Iron and Steel Industry

The iron and steel industry is one of the most carbon-emitting industries, constituting about 8 percent of the entire carbon dioxide emission amount in the world. Therefore, the demands for the development of carbon capture and utilization (CCU) technology in iron and steel industries are urgently increasing.

Generally, in CCS, 90% capture rate with 95 % CO₂ is recommended for emission gases. However, In viewpoint of CCU, each industry requires a specific concentration of CO₂ to meet its requirement of desired products and operating conditions. Especially, the iron and steel industry needs only the concentrated CO₂ from effluent gases for CCU, instead of 95 % CO₂. Then, the recovery rate of at least 90% becomes an important factor in process efficiency. In this perspective, the pressure swing adsorption using weak adsorbents is highly advantageous to achieve the desirable purity and recovery of a target gas.

In this study, the gas mixture (CO₂, H₂, N₂, and CO) is applied as a feed gas, which matches the composition of the real steel process off-gas. The mathematical dynamic model using experimentally obtained isotherms and kinetics is confirmed with experimental breakthrough curves using silica-based adsorbents. Then, a multi-bed PSA process using layered beds is developed. Sequential and multiple adsorption steps and purge steps are applied to design the cyclic configuration. Then, the sensitivity analysis of various conditions such as step time or feed pressure is conducted using the developed dynamic model.