Hydrogen recovery captures the hydrogen from refinery gas streams coming from the hydrotreaters and hydrocracker.
There are three common methods for hydrogen recovery:
- Cryogenic hydrogen recovery - The gas mixture is cooled to the point that the non-hydrogen components drop out as a liquid, allowing separation from the hydrogen
- Pressure swing adsorption (PSA) - The gas mixture is passed through a molecular sieve solid adsorbent, which adsorbs the hydrocarbon and allows the hydrogen to pass through
- Membrane diffusion - The gas mixture is separated by using pressure to force the hydrogen through a membrane that is hydrogen permeable but not permeable to large hydrocarbons