(338h) 2-Layered-Bed H2 PSA Process for Low H2 Feed Gas

One of current focuses in the energy field is on the use of hydrogen. It is needed to recover H₂ from various sources, including low H₂ feed, due to the lack of H₂ sources in future. The H₂ PSA process was studied for hydrogen recovery from low H₂ feed gas, produced from the steel production process; relatively low H₂ concentration (38 vol.%), high CO₂ concentration (50 vol.%), and the other minor three components (CH₄, CO, N₂).

In this study, activated carbon and zeolite 5A were used as adsorbent. The adsorption dynamics of layered bed (activated carbon : zeolite 5A = 7:3) were compared to those of single adsorbent beds. Due to the strong adsorption and high adsorption heat of CO2, it was expected that the PSA using single adsorbent bed could not give a high purity product without significant sacrifice of recovery. The layered bed was more efficient, but N2 worked as a major impurity.

2-bed H₂ PSA using layered bed was performed at various conditions; adsorption pressure, feed flow rate, adsorption step time and P/F ratio. The performance of each condition was compared to each other with respect to purity and recovery.

The theoretical mathematical model combined by mass, energy, momentum balances with adsorption equilibrium and rate equations were applied to the PSA process simulation. The inside adsorption dynamics were analyzed by the simulator.