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Content Type:Q&A

Question:

I'm working on a fuel cell project.  How can I estimate the energy required to compress a gas (hydrogen) to 3,600, 5,000 and 10,000 psi?

Answer:

American Gas Compression Services has an on-line compression requirements calculator. You enter suction pressure (psig), discharge pressure (psig), capacity (in millions of cubic feet per day), "K" value or ratio of specific heats for the gas, specific gravity (generally 0.65 for natural gas), gas inlet temperature, and site ambient temperature and altitude. Their program determines the brake horsepower (bhp) required per million cubic feet per day of gas throughput. A chart is provided at their website that gives bhp requirements for single, two and three-stage compressors with suction pressures ranging from 0 to 600 psig and discharge pressures up to 1000 psig. Check out their website at http://www.agcsi.com/

For higher gas pressures, go to the ARIEL Corporation website. ARIEL provides free compressor selection software that you can download. Again you enter the desired throughput, suction and discharge line pressures, site altitude and design basis temperature, and gas properties. The program can determine the brake horsepower requirements for multi-stage gas compressors—then assist the user to select an actual compressor.

Cameron International Corporation offers free CASCADE and eAJAX Sizing Programs software.

I completed a series of runs for natural gas using the ARIEL software. Assuming a suction line pressure of 5-psig, a suction temperature of 80 degrees F, and a throughput of 1 million cubic feet per day of 0.65 specific gravity gas, I determined the following bhp values for 1,000, 3,500, 5,000, and 10,000 psig discharge pressures. (I assumed a 5-stage compressor was to be specified). Note that the compressor efficiency should be embedded in these brake horsepower values.

Brake Horsepower per 1 MMcfd Gas Discharge Pressure, psig

Discharge Pressures (psig) Brake Horsepower 
1,000 265 
3,500 339 
5,000 363
10,000 419

Topic: Industrial Technologies--General
Topic: Onsite Power--Fuel Cells
Topic: Transportation--Fuels
Sector: Commercial
Sector: Industrial
Sector: Agricultural
Content Type: Q&A
Keywords: gases, compressing, discharge pressures
ID:  2379