Return line Injection Well

Discussion in 'Pumps and Tanks Well Forum & Blog' started by NormanWell, Oct 1, 2010.

  1. NormanWell

    NormanWell New Member

    Messages:
    3
    Location:
    Norman OK
    My static water level for my injection well for geothermal is at the 150 feet mark. THis means that I have a vacuum in my line after my bell&gossett flow control valve. This is fine, but am I getting minerals coming out of solution in the return line? Should I worry about it? Can I but a back pressure valve in the return line so that I get zero pressure at the flow valve instead of a vacuum?

    Thanks,
    NormanWell
  2. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Sounds interesting - you are heating with ground water? why would a vacuum give you minerals? How about some more info?
  3. NormanWell

    NormanWell New Member

    Messages:
    3
    Location:
    Norman OK
    Ok,

    After my control valve the water runs down to the injection well which is 150 feet deep. This is more than 32 feet above the surface of the water level in the well. So I have a 32 feet columb of water up the pipe and the rest with no air in it. (the end of the pipe is under water). Thus, I have 118 feet of vacuum. If my water level in the well was less that 30 feet from the surface, I would not have a vacuum. Now that I have almost a pure vacuum, the steam table show that water will evaporate at 78 degrees at this vacuum level. With the water return temp at 82 degrees, the water is vaporizing in the pipe. This causes the loss of vacuum which causes the water in the pipe at the 32 foot mark to drop. How far it drops depends on the temperature of the the water and the vacuum level. The problem with this is I am loosing vacuum and this helps reduce the amount of pumping energy. What I think I need to do, is install a pressure relief valve at the 32 foot mark and set it to hold back enough pressure to see a 5 pound pressure at the control valve. This will keep the pipe full and get back my 32 foot of water. However, the valve placement as to be right. It must be placed so that there is always water on the discharge side, never the vacuum. If not, you are back in the same boat. I am thinking that what ever pressure you set the relief valve too, is the amount of lift the pump must pump. The total head would be the lift, any system pressure and pipe friction.

    Vacuum gives you minerals because all the water is vaporized and you are left with the stuff. This stuff is what I am not sure will desolve again once it hits the well. Also, the fact that I am vaporizing then loosing vacuum, may indicate that I might just have a lower water columb with no vaporizing. As the water cools, the water columb rises.


    Bottom line, I am not sure this will work.

    Thanks,
  4. masterpumpman

    masterpumpman New Member

    Messages:
    729
    Location:
    Virginia Beach, VA
    I suggest you contact gewbank@geotctest.com. I'm sure Garen can assist you. Tell him "Porky" referred you to contact him.
  5. ncgeo

    ncgeo In the Trades

    Messages:
    47
    Location:
    North Carolina
    Just a thought, would installing a vaccum breaker (similar to ones used on irrigation systems in some jurisdictions) help?
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