3 replies to this topic

[vineguimaraes]

Hello

I am in the middle of my final project at university, and I need to send hydrogen gas for storage at 250 bar.

I am thinking about a multi stage compressor with heat exchangers between them, but I can´t find a good compression rate with a reasonable temperature discharge.


My system consists of 340 kg/h.

Can someone please tell me untill what temperature I can handle the hydrogen gas, ou some examples of this compression system?

Thank you.

[ankur2061]

Hi,

For such a service with very low flow rates and high compression ratio, multi-stage reciprocating compressors would be the most suitable. Since it is hydrogen service the compression ratio per stage should be maintained such that the discharge temperature per stage does not exceed 135 deg C (API 618 guidelines for hydrogen rich service). The gas from each stage shall be cooled using inter-stage coolers before it enters the next stage.

Regards,
Ankur.

[Bobby Strain]

Diaphram compressors are typically used for this service.

Bobby

[Art Montemayor]

Vineguimaraes:

You are proposing to compress hydrogen from an unstated suction pressure (?) and temperature (?) to a discharge condition of 250 bar(?) and an unstated temperature (?). Please don’t mess up your future engineering career by failing to state what the values of the (?s) are. I am not reprimanding you; I simply want to help you establish yourself as a successful future engineer. You MUST communicate all the required, necessary basic data necessary to respond to a query in a concise and accurate manner. This is a basic requirement in engineering and will be imposed on you as you further your career. This is the most important item I can help you on. I can also give you factual and experienced advice on how your procedure is carried out in industry since I have done it many times before. This part of my response is not as important as the first one:

• Since you don’t furnish accurate and complete basic data, I have to make several assumptions. Your suction conditions are atmospheric pressure (14.696 psia) and 60 ^oF. Your discharge conditions are 250 bara (3,625.94 psia) and 30 ^oF (86 ^oF).
• The flow rate of the compressed hydrogen is 340 kg/h = 1,496 lb mol/h = 567,717 Scfh = 9,462 Scfm (measured at 60 ^oF & 14.686 psia). This is NOT A SMALL volumetric flow rate and the type of service is quite conventional (in the USA), using 4 to 5 stage reciprocating compressors. You would require several, relatively large machines.
• I have discussed this specific subject several times in past threads within our Forums and you can access the information – complete with schematic diagrams and flow sheets – detailing how the operation is carried out and controlled.

If this is your end-of-university project, I recommend you research our Forums for all the above information, go back and apply your basic thermodynamic studies, and do some additional research on reciprocating compressors, their controls and features. The quantity of stages I would recommend for this service is 5 and the reason I would select this is due to the expected discharge temperature(s) of each stage. As Ankur has stated, you require interstage coolers (and vapor-liquid separators, if the suction gas is humid) as well as an aftercooler on each compressor. If electric motor driven, the driver is usually a synchronous motor running at 400 – 600 rpm (max.)

If you require additional, specific information and details, please state them.