Q & A > Question Details
Please advice about the operation practice of the reciprocating compressor in order to increase life time of discharge valves in the compressor cylinders.
We're operating a Hydrogen plant using water electolyser cells - using alkaline which is KOH, operating temp 70C and production rate 170 nm3/hr where reciprocating machines are used to suck hydrogen from a gas holder directly after the cells and discharge it to the high pressure line to the customer (200 bar).
The Gas Compressor comprises of 5 stages, where first stage is consits of 2 plate valves.
The problem always happens to first stage Gas Compressor. Just 15~30 days after starting, the discharge valves in the cylinder always develops a leak and fails. Upon dismantling, we used to find some debris and gum particle (deposits) in between valve plate and valves top. The problem occurs over and over again.
The deposits particle is KOH which comes with the hydrogen gas vapor passing through the suction filter and rest on the valve.
 
Answers
19/06/2014 A: Bruce Carr, Suncor Inc, bcarr@suncor.com
Switch to DR "Magnum" valves...
29/07/2013 A: keith bowers, B and B Consulting, kebowers47@gmail.com
You have done a very good job at figuring out what is causing the valves to fail. Now you must improve feed-gas clean-up to remove ALL such contaminates if you expect these valves to provide good service lives.
Hydrogen compression is a difficult service and compression ratio per stage should be kept below about 3.5 with 4.0 absolute maximum with very careful design details to control heat at top piston ring land. 'Cool Operation' is one key parameter is achieving long reed valve life in this service. Cleanliness of feed gas is an absolute requirement.
It will probably require a water wash to remove the residual KOH dust. Use a appropriately sized packed tower with recirculating water, spill some from bottoms recirculation pump discharge to waste to keep pH from getting too high--stay below about 8.5. add fresh water make-up to top 'reflux.' Two theoretical contact stages of contact height should be enough, but check with the packing vendor.