Compression of methane

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How can i compress methane without a risk of it exploding? I want to compress methane generated form biomass into a storage tank (a small propane tank) with out flattening my workshop. Does anyone know a safe way to do this?
Thank
Sam
 

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  • #2
Q_Goest
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There's no danger in compressing methane unless there's air (ie: oxygen) in it.
 
  • #3
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Thank you for the answer but perhaps i ought to rephrase, can i use a regular air compressor? Or is that likely to cause a problem?
 
  • #4
Q_Goest
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The quick answer is no. Virtually all compressors have leaky piston rings so that ring leakage must be taken somewhere safe if the gas is a flammable. Air compressors allow that leakage to go to atmosphere.
 
  • #5
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I had the same concern but wasn't sure, what about using an AC pump out of a car?
 
  • #6
Q_Goest
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That might work since that's a scroll compressor which is a completely sealed unit.
 
  • #7
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Cool, well all i have to do now is figure out how to remove the water,CO2 and hydrogen sulfured and i can fire up my BBQ:) thank you
 
  • #8
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The BTU content of your methane can vary greatly, from barely hot enough to sustain combustion to blue hot flames. PLEASE, if you compress any flammable gas, include an oxygen sensor on the compressor suction (intake) line to prevent a dangerously explosive mix from being put into your compressor.
Methane from biomass can be handled by the same techniques that have been used in handling natural gas for decades. Water can be removed by thermodynamic means (aka a 'drip") or by running the gas through a bath of triethylene glycol to strip the water out, then cooking the water out of the glycol and recirculating. The gas laws are your friends on this one.
Carbon dioxide comes out with a bath of amine in much the same way that glycol attracts H20.
Take a look here: http://www.naturalgas.org/naturalgas/processing_ng.asp [Broken] and here: http://www.newpointgas.com/

I spent over a decade running natural gas production from the wellhead to the sales tap...fascinating stuff.
 
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  • #9
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Would an o2 sensor form a car engine work? And that you for the links they are a big help!
 
  • #10
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I do not know what range automotive O2 sensors operate in.
You need to keep your O2 content below 2% as far as I know, to stay in a safe range. Our sensors ran in contact with the gas stream itself, sampling 2-5 cfh. fairly simple concept: sensor- meter-alarm. The high oxygen alarm needs to be wired to a kill switch for the whole enterprise. With enough compression and some oxygen you can make an explosion just like in a diesel engine, but it will probably be a one-stroke occurence. With all that being said and with the caveat that you will die if you try this, I once loaned a leaky 50 year old one cylinder air compressor to a friend with a gas well that was not producing enough to supply his house. He hooked the intake of the compressor to the output of the well and the output of the compressor tank to his household supply line and turned it on. That old thing still had enough ring seal left to pull a slight vacuum on his gas well and send about 30 psi to his house. He ran it that way all winter and then hauled the compressor back to me. I will point out that the gas well was a good ways from the house, fortunately.
 
  • #11
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Well I would very much like to avoid the one stroke workshop removal experience, so I will get a good o2 sensor and make sure to have a fire srepression system. What would recommend if there is a fire?
 
  • #12
berkeman
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Thread closed for Moderation...
 
  • #13
berkeman
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This discussion is too dangerous to be allowed to continue here on the PF, especially given the lack of experience of the OP. The thread will remain closed.
 
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