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Condesation/Fractional distillation of air

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LAN_403

2Spoons

Tue Sept 04 2012, 10:03PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
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Posts: 615

Oil traps are an off-the-shelf item at any pneumatics supplier. The harder part is the water and CO2 traps. Domestic freezer takes care of the water, CO2 is a little harder, but you can make a CO2 absorber using a bed of damp sodium hydroxide.

IamSmooth

Tue Sept 04 2012, 10:40PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567

2Spoons wrote ...

Oil traps are an off-the-shelf item at any pneumatics supplier. The harder part is the water and CO2 traps. Domestic freezer takes care of the water, CO2 is a little harder, but you can make a CO2 absorber using a bed of damp sodium hydroxide.

Since Lye is dangerous, how is this prepared? Are the NaOH put in a sealed tube and the air runs through it?

Also, I read the links of those who were trying to liquify air, but I did not see any of them report success.

2Spoons

Wed Sept 05 2012, 03:42AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
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I'd be putting the lye into a steel or stainless steel can, with the air inlet running to the bottom and outlet at the top. Some sort of removable lid for replacement when the lye is used up (converted to sodium carbonate). I suppose you could use calcium oxide or hydroxide too, but would would end up with a can of concrete.

Ooo! I think I've just found what you want

Ash Small

Wed Sept 05 2012, 05:57AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

2Spoons wrote ...

I suppose you could use calcium oxide or hydroxide too, but would would end up with a can of concrete.

I've worked on industial pocesses that spray a solution of calcium hydroxide into the exhust gas from a 'waste to energy' incinerator/power station (12MW) to 'scrub' the CO2 from the exhaust gas.

Bubbling it through 'lime water' or 'milk of lime' should do the job though, and you won't end up with concrete

(we did that at shool, I seem to remember)

you'd want the CO2 'scrubber' before the freezer for removing H2O, obviously.

Shrad

Wed Sept 05 2012, 07:07AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
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that's what they do in incinerators, I have worked several times on such installations and they use lime water bubbling, electrostatic filters, and water curtains

IamSmooth

Wed Sept 05 2012, 01:02PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567

2Spoons wrote ...

I'd be putting the lye into a steel or stainless steel can, with the air inlet running to the bottom and outlet at the top. Some sort of removable lid for replacement when the lye is used up (converted to sodium carbonate). I suppose you could use calcium oxide or hydroxide too, but would would end up with a can of concrete.

Ooo! I think I've just found what you want

This did look promising. After reading the fill times and noting the compression cyclinder size, I think the output will be too low. I am hoping to find a 100-200 bar compressor at some point that is not crazy expensive.

2Spoons

Wed Sept 05 2012, 10:18PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
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I've also seen people claiming 1800psi from two series stacked refrigeration compressors. Cooling and safety would be the primary concerns.

Dr. Slack

Thu Sept 06 2012, 06:58AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Do you have any Scuba buddies? You may be able to borrow a 300 bar tank. With only the fills to pay for, you could do some small scale experiments before comitting to a compresser.

IamSmooth

Thu Sept 06 2012, 04:59PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

Dr. Slack wrote ...

Do you have any Scuba buddies? You may be able to borrow a 300 bar tank. With only the fills to pay for, you could do some small scale experiments before comitting to a compresser.

No scuba or paintball buddies. I've called a few places, but new small ones are over $5k. Bigger ones are over $10k. Ebay has come up blank so far.

I'm going to have to wait until I find one at the right price. It also has to have a good flow rate. It takes 645L (STP) of N2 to make 1L of liquid N2. I know I can do this, but I want to be safe about it.

Microwatt

Thu Sept 06 2012, 09:08PM

Registered Member #3282 Joined: Wed Oct 06 2010, 05:01PM
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why don;t you spare yourself the trouble and cost and just buy the ln2. i heard its cheap and you can bubble oxygen through it to make liquid 02

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