Adsorption releases heat. The temperature of a PSA bed rises slightly (5–20
F)
during the adsorption steps and drops back down as the bed is depressured. If any
liquids reach the bed, the adsorption heat rise will be very high, so liquids are
strictly excluded.
The steps in a typical PSA cycle applied to one bed are shown in Table 12. There
are several sub-steps in the actual control software, but the cycle will generally
Product
Hydrogen
1
2
3
4
5
Adsorbers 1 through 5
Ads. #1 Adsorbing
Ads. #2 & 3 Depressuring
Ads. #4 Final Blowdown
Ads. #5 Repressuring
Offgas/Tailgas
To Surge Drum
& Disposal
Feed
Gas
All valve
sequences are
controlled by a
programmable
logic controller.
Fig. 22 Simplified process flow diagram of a 5-bed PSA unit
Table 12 Example PSA bed cycle steps
Hydrogen Production and Management for Petroleum Processing
627
F)
during the adsorption steps and drops back down as the bed is depressured. If any
liquids reach the bed, the adsorption heat rise will be very high, so liquids are
strictly excluded.
The steps in a typical PSA cycle applied to one bed are shown in Table 12. There
are several sub-steps in the actual control software, but the cycle will generally
Product
Hydrogen
1
2
3
4
5
Adsorbers 1 through 5
Ads. #1 Adsorbing
Ads. #2 & 3 Depressuring
Ads. #4 Final Blowdown
Ads. #5 Repressuring
Offgas/Tailgas
To Surge Drum
& Disposal
Feed
Gas
All valve
sequences are
controlled by a
programmable
logic controller.
Fig. 22 Simplified process flow diagram of a 5-bed PSA unit
Table 12 Example PSA bed cycle steps
Hydrogen Production and Management for Petroleum Processing
627