Bed configurations in CO vacuum pressure swing adsorption process for basic oxygen furnace gas utilization: Experiment, simulation, and techno-economic analysis

Abstract

CO is a primary component of basic oxygen furnace gas (BOFG) and can be used for producing fuel and various value-added chemicals. It can be typically obtained from steel mill gases via separation. Herein, suitable bed operation configurations for vacuum pressure swing adsorption (VPSA) were determined based on the desired CO product purity (PURCO,P) when separating CO from simulated BOFG (CO:CO2:N2:CH4 = 65:20:10:5 mol%) using a numerical model validated with experimental data. By changing the operation steps, one case of two-bed, four-step (2-bed), one case of three-bed, five-step (3-bed), and two cases of four-bed, six-step (4-bedbase and 4-bedmod) operation configurations were considered at a setting temperature of 60 ℃, desorption pressure of 0.13 kgf cm−2, and adsorption pressure in the range of 2.5–4.0 kgf cm−2. The sensitivities of these four operation configurations were evaluated to compare the separation performance and economic benefits of each operation configuration. In the 2-bed case, the PURCO,P demonstrates a separation limit (92.1–92.7 mol%). When targeting PURCO,P ≥ 99.00 mol%, the 3-bed case presents the most favorable CO recovery values (RECCO,P; 92.97–94.13 %) and unit production costs of CO (UPCCO; 0.252–0.357 US$ Nm−3), whereas the 4-bedmod case presents optimal RECCO,P (82.06–91.65 %) and UPCCO values (0.273–0.406 US$ Nm−3) when targeting PURCO,P ≥ 99.99 mol%, under the same operating conditions. These results indicate cost-effective CO-VPSA process configurations for enriching CO from BOFG, based on the target PURCO,P.