LOW-CARBON HYDROGEN PRODUCTION THROGH PRESSURE SWING ADSORPTION-CONFIGURATION OPTIMISATION

Abstract

This research conducted an optimization process for PSA unit by increasing the complexity of the PSA step design, which allows a PSA cycle to have a lower input flow to one adsorption column and more pressure equalisation stages. Aspen Adsorption V12 was used to conduct a dynamic simulation of two, four, six, nine, twelve-bed that produced 99.9% hydrogen purity for industrial fuel application. As a result, the twelve-bed model had the highest H2 recovery 84.46 %, CO2 purity 79.84 %, and energy consumption 34 MJ/kgH2. However, it had the lowest H2 productivity, which was 190 moleH2/kgads/day. Moreover, the study investigated two different models for four-bed design to evaluate the performance of the PSA unit when the providing purge step (PPG) location was changed. The PPG step was implemented after adsorption step in the first configuration. On the other hand, the PPG step was implemented after first equlisation depressurisation step (ED1) in the second design. The second model had higher H2 recovery, productivity, CO2 purity, which were 74.89 %, 74.13 %, and 560 moleH2/kgads/day, respectively. Also, it consumed less energy to produce H2 compared with first model, which was 13.59 moleH2/kgads/day. For the sensitivity analysis, two parameters was investigated; adsorption pressure, purge-to-feed ratio (P/F). The four-bed model was used in this section. Notably, the P/F had a significant impact on the overall process. Increasing the P/F from 5 % to 15 % led to increase in the H2 purity from 97.14 % to 99.9 %, while H2 recovery, productivity, and CO2 purity dropped significantly. Regarding adsorption pressure, increasing the adsorption pressure from 25 bar to 35 bar led to slight increase in H2 purity from 99.82 % to 99.92, also, H2 recovery increased from 478 to 486 moleH2/kgads/day. Nevertheless, the H2 recovery and CO2 purity dropped considerably by increasing the adsorption pressure.