Laboratory hydrogen drying after a PEM electrolyser
A research centre wanted to dry wet hydrogen from a lab PEM electrolyser at a few litres per minute. We estimated the water load first and then built a drying train around it.
Starting point
A research team operates a small PEM electrolyser on a lab bench. The hydrogen leaves the stack saturated with water and must be dried before it reaches the downstream experiment.
Task
Quantify how much water has to be removed, choose a suitable adsorbent and protect the drying stage from liquid water and the experiment from desiccant dust.
How we sized it
- 1
Estimate the water load
Saturated hydrogen at 25 °C carries about 3.1 vol.-% water: roughly 1.4 g/h at 1 L/min and 10 g/h at 7 L/min (estimate). Cooling to 5 °C first reduces this to about 2.8 g/h at 7 L/min.
- 2
Size the adsorbent
Molecular sieve takes up roughly 15–20 % of its own weight in water (guide value). The refill or change interval follows directly from the water load.
- 3
Choose the media
RF-AC-25064-4A is pre-filled with 4A molecular sieve. 3A molecular sieve is available as loose refill media only.
- 4
Build the train
Catch pot RF-H-122-CP for water slugs → coalescer RF-H-122 with RF-C-12057-HE → adsorption stage (sized on request) → dust filter RF-H-126 with RF-P-12057-HE.
Recommended configuration
Cartridge pre-filled with 4A molecular sieve; adsorber housing sized on request.
Product details
Limits & open points
- Water-load figures are estimates for saturated gas; the adsorber is sized on request with the real operating data.
- Regeneration of molecular sieve (approx. 175–315 °C with dry purge gas) takes place externally, not in the filter housings.
- No dew-point guarantee is given without a sizing based on the actual data.
Result
A transparent water balance and a modular drying train the lab can start with and extend, with refill media instead of disposable dryers.
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