Diaphragm compressor compression ratio?

[iainuts]

Any thoughts on what the maximum compression ratio should be for a diaphragm compressor (metal diaphragms)? Assume hydrogen gas.

Alternatively, how many stages would be required to take gas from 100 psig to 6000 psig?

 

[georgeverghese]

Just had a look at the online brochures for these diaphragm compressors for H2 service - they seem to have some internal coolant recirculation for removing the heat of compression in each stage, which should give you a higher allowable compression ratio per stage than would be possible otherwise without internal compression heat removal (similar to that for oil flooded screw compressors in refrigeration service, or even in air service)

Hence, it wont be possible to approximate this as a typical recip compressor to get this information you're looking for, to my knowledge. Best to talk to the compressor vendors.

In the final stages of compression, the polytropic exponent n for H2 gas at 6000psig would be well off the value at low pressures. Dont know if process simulators can predict the corresponding adiabatic k value correctly at this pressure. Thats another reason to defer to what the vendors have to say.