Table 14 Some common PSA problem symptoms and possible causes
Symptom
Possible causes/remedies
Repressurization
PLC or other instrument problem
Too long or slow
PLC or other instrument problem
Repressurization valve/instrumentation problem
Low product header pressure (look at users)
Too short or fast
PLC or other instrument problem
Associated control valves or instrument problems
Blowdown
Too long or slow
PLC or other instrument problem
Blowdown valve/instrumentation problem
High blowdown header backpressure (look
downstream)
Valves leaking into header from other vessels
Too short or fast
PLC or other instrument problem
Blowdown valve/instrumentation problem
Purge
Too long, slow, incomplete
Associated control valves or instrument problems
Valve leakage from another vessel
Low product purity
Too short or fast
PLC or other instrument problem
Instruments/valves on vessel providing purge gas
Pressure/flow bumps/variations
Feed/product headers
See repressurization symptoms
Off-gas/tail-gas header
See blowdown or purge symptoms
Problems with off-gas or purge control system
Valve leaks or instrument problems in associated
valves
Controls/instrumentation problem around off-gas
surge drum
Tail-gas compressor problem (if applicable)
Feed or product flow fluctuations
See repressurization symptoms
Feed flow varying (check upstream)
See purge and blowdown symptoms
Low product purity
PLC or other instrument problem
Adsorption time set too long
Adsorbent damage or loss (from another problem)
See repressurization, blowdown, and purge
symptoms
Wet or hot feed gas – possible carryover
High feed flow rate
High off-gas/tail-gas pressure (look for downstream
problem)
Bad analytical data
(continued)
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S.A. Treese