zeolite regeneration

Discussion in 'Physics' started by phddas, Jul 28, 2013.

  1. phddas

    Thread Starter New Member

    Jul 25, 2013
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    Hi

    In my home project to produce Oxygen and Nitrogen on demand, I read online bout zeolite regeneration of 5A and 13X.

    In order to avoid system design, can I regenerate the zeolites by vacuum or any other means which does not require heating and cooling them?

    Thank you
     
  2. WBahn

    Moderator

    Mar 31, 2012
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    To the best of my knowledge, oxygen concentrators (like I have for supplemental O2) just use two chambers filled with zeolite and ping pong back and forth between them. For each one, they pressurize it with outside air forcing the zeolite to absorb most of the nitrogen, they then vent into the output O2 line down to some level and vent to atmosphere for the rest of it and let the zeolite give up it's N2. I don't think there is any vacuum, heating, or cooling (other than due to the compression/expansion) going on at all. Mine can deliver 5 liters/min and alarms if the output O2 concentration drops below 90%.
     
  3. WBahn

    Moderator

    Mar 31, 2012
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    A good description can be found on Wikipedia:

    https://en.wikipedia.org/wiki/Oxygen_concentrator

    The big blue beast they show is the exact model I have.

    The total cycle time is only 6 seconds and the zeolite absorbs basically all of the N2 out of the incoming air in just a fraction of that and then continues to pull it out in steady state until it starts saturating (which would start occuring a bit after the 3 second charging time). The N2 doesn't start coming out of the zeolite until the pressure has dropped quite a bit from it's peak. The pressure is only 20psi, so not that much at all.

    What I have no clue about is how the zeolite is actually situated within the cylinder in order to ensure very rapid access to it's nominal surface boundary and prevent it from crumbling/packing. Maybe it isn't needed and you just put a solid piece of zeolute in there, but I'm thinking there's more to it than that.
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    It looks like it is easier than I expected.

    http://www.alibaba.com/product-gs/737059028/Oxygen_Concentrator_Zeolite_Molecular_Sieve_13X.html?s=p

    Apparently you just pour this stuff into your chamber and rely on the natural packing of the pellets/balls to provide for adequate gas flow to access the pellets.

    This stuff is only about $1/lb. Makes me wonder why the commercial concentrators are so expensive (mine was $600 and portable ones are still $2000 to $4000). The cost of materials can't be that high give that you need three pressure chambers that can withstand a working pressure of 20psi, three electrically operated valves, an oil-free compressor that can deliver 20psi at about 25 lpm, some zeolite, an oxygen sensor, and some very simple control electronics.

    Probably gives some idea of what is involved in getting a product approved for medical use and satisfying all the up-front and on going bureaucratic red tape.
     
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