Exploring enhanced CO2 separation from blast furnace gas: A multicolumn vacuum swing adsorption approach with process design and experimental assessment

Excessive emissions of carbon dioxide (CO 2 ) are a major driver of global warming. Blast furnace gas (BFG) represents a major source of CO 2 emissions in the steel industry, accounting for approximately 30 % CO 2 emissions among the industry sectors. Hence, effective CO 2 capture from BFG is imperative. This study presents an approach utilizing the vacuum swing adsorption (VSA) technology to capture CO 2 from BFG. A 6-column VSA rig was designed and constructed to separate CO 2 from a simulated BFG (CO 2 /N 2  = 20 %/80 %) using zeolite 13X as adsorbents. The VSA process involved steps of adsorption, desorption, heavy product purge, light product re-pressurization, and pressure equalization. Five different process modes, i.e., 1-column and 3-step, 2-column and 6-step, 2-column and 8-step, 3-column and 9-step, and 4-column and 16-step configurations, were implemented to evaluate the influence of various process design factors on the separation performance. Additionally, a 6-column and 36-step process was devised to conduct a parametric study of VSA cycles by varying the adsorption duration and desorption pressure. Results revealed the pivotal role of heavy product purge and pressure equalization on the separation performance. The six-column process achieved a CO 2 purity and recovery of 94 % and 82 %, respectively, with a energy consumption of 0.76 GJ/tonCO 2 when employing a desorption step duration of 240 s and pressure of 8 kPa. In addition, a method of process optimization based on the bed capacity ratio, C, was introduced in this study, which provides a dimensionless quantity of the utilization of the adsorption column. Moreover, capturing CO 2 from BFG through the VSA cycle not only enhances its heating value but also yields substantial advantages in terms of mitigating CO 2 emissions.