Single- and double-bed pressure swing adsorption processes for H2/CO syngas separation

Abstract

Pressure swing adsorption (PSA) technology is an effective method to extract hydrogen from synthesis gas (syngas) and purify the produced hydrogen. The dynamic adsorption models for syngas (H2/CO 70/30 mol%) treatment by single- and double-bed PSA systems with zeolite 5A were developed. The breakthrough curves of the single-bed hydrogen purification PSA system were studied. Subsequently, the performance of the single- and double-bed PSA cycles was studied. The models were built and implemented using the Aspen Adsorption platform. After model validation and successful simulation of the breakthrough curves in the single-bed model, the simulation of five- and six-step PSA cycles in the single-bed and double-bed models, respectively, were carried out. A parametric study of both single- and double-bed models was then carried out. The results reveal that the simulated breakthrough curves agree with the experimental curves very well. The parametric study shows that, with certain range of 1.38 × 10−6 to 2.08 × 10−6 kmol/s for feed flow rate, the adsorption time of 240–360 s for single-bed and 180–300 s for double-bed, a lower feed flow rate and shorter adsorption time leads to higher purity, lower recovery, and lower productivity. For the double-bed PSA model, the influence of the pressure equalization time, with the range of 5–40 s, on the PSA process was also studied. It can be found that, as the pressure equalization time increased, better purity and recovery but lower productivity were obtained. The results show that, at a feed flow rate of 1.58 × 10−6 kmol/s, the recovery and productivity of the double bed are higher by 11% and 1 mol/kg/h, respectively, than those of the single bed.