A PSA plant consists basically of the adsorber vessels containing the adsorbent material, tail gas drum(s), valve skid(s) with interconnecting piping, control valves and instrumentation as well as a control system for control of the unit.
The pressure swing adsorption process has four basic process steps:
– Adsorption
– Depressurization
– Regeneration
– Repressurization
To provide continuous hydrogen supply, minimum 4 adsorber vessels are required. The figure on page 6 shows the combination of the sequen-
ces of four adsorber vessels as a pressure-time-diagram.
Adsorption
Adsorption of impurities is carried out at high pressure being determined by the pressure of the feed gas. The feed gas flows through the adsorber vessels in an upward direction. Impurities such as water, heavy hydrocarbons, light hydrocarbons, CO2, CO and nitrogen are selectively adsorbed on the surface of the adsorbent