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Condesation/Fractional distillation of air

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LAN_403

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Thu Dec 12 2013, 10:41PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

It sounds like you are practically done! It is really interesting to follow you progress, and it sounds like your system has the ability to generate quite large quantities of ln2 (certainly larger than any other hobby technique I have seen)

IamSmooth

Fri Dec 13 2013, 02:21AM

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

My cool-down chart:

1386901268 190 FT144039 Liquid Nitrogen Cooling

IamSmooth

Sun Dec 15 2013, 09:26PM

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

Here is a video of 1/2 hour of running the generator. My 14 year old daughter was holding the camera and was taken by surprise by the splashing made by the liquified gas. A lot of the liquid gets vaporized as it cools the dewar. I plan on working on a larger internal reservoir and running the generator for a few hours.

Here is the video

The input gas is 98% nitrogen from my homemade PSA. I initially ran the generator off of air until I hit -220F. It seems I'm still getting some oxygen in the collection. I will probably start the PSA sooner next time.

Billybobjoe

Sun Dec 15 2013, 10:58PM

Registered Member #396 Joined: Wed Apr 19 2006, 12:55AM
Location: Pittsburgh, PA
Posts: 176

Awesome! I think people would definitely be interested in this! I know I am.

I think its just difficult to comment about because not many people have done it before. Personally I don't think a step by step procedure is necessary, but I'm sure some diagrams and descriptions of materials used would attract some interest.

Wastrel

Mon Dec 16 2013, 01:11PM

Registered Member #4095 Joined: Thu Sept 15 2011, 03:19PM
Location: England.
Posts: 122

My main questions would be,
1. If I bought the pump from new would I need to remortgage my house first?
2. What steps were taken to prevent and mitigate the high pressure parts exploding?

IamSmooth

Mon Dec 16 2013, 02:10PM

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

All parts are standard and easily obtainable
The most expensive part was the compressor, but you can get one from 500 to $2000 depending on your luck and patience

The parts are all high pressure grade. I forgot the exact numbers but the tubing is good to +5000 psi
This allows for a 3x safely factor
The tubing is good for cryo temps
The throttle is cryogenic rated
The low pressure connections are machined teflon to prevent low temp failure

Nothing is blowing up

The problem I see with others trying to do this they are using refrigerator compressors

Wastrel

Mon Dec 16 2013, 03:32PM

Registered Member #4095 Joined: Thu Sept 15 2011, 03:19PM
Location: England.
Posts: 122

I have to say, that sounds really well done.

I'd also be interested in details of the PSA as a seperate project. By itself a source of oxygen, or a duel unit for pure nitrogen, could be pretty useful and it sounds like the parts are easier to get.

IamSmooth

Thu Jan 09 2014, 01:26AM

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

The website tutorial is progressing here

I would appreciate any feedback, suggestions or points if something is not clear.

My last run got to -320F in 40 minutes from a starting temp of 36F. I collected close to 300cc in one hour. Unfortunately, the sun set so the video was poor. I will get another one soon.

Wastrel

Sat Jan 11 2014, 02:15PM

Registered Member #4095 Joined: Thu Sept 15 2011, 03:19PM
Location: England.
Posts: 122

Site starting to look really good.

You could add to your intro. Usual method of liquefying something is to compress it until it changes phase. You could explain why this doesn't work and maybe mention the method of cascades.

Stirling cycle and turbo expander are just two ways of making the gas do work. There are other implementations, many have lubrication problems at low temperatures.

You might mention that the industrial process uses 50atm as the low pressure side and 200 high pressure, which gets 75% of the cooling capacity but the compressor only needs to do 4:1. I think both Linde and Hampson used this in their original equipment. Apparently Linde's was so badly insulated it took 2 days to get down to liquid air temperatures.

IamSmooth

Tue Feb 04 2014, 04:41AM

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

Well, after a long time from the first question the project is done. I have made a detailed video showing the process of building the unit. While it does require some work, anyone can do this. I hope students in college and others will find this helpful if they wish to undertake this endeavor.

The cool video is here with a guest appearance of my cat at the end.

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