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Thread: Did you really know this about procon pump self-priming?

  1. #21
    Join Date
    Mar 2013
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    Hoosick Falls
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    2,000

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    Quote Originally Posted by Wizbi View Post
    I track on the pressure increase, assuming you are accomplishing it by turning your concentrate adjustment valve so as to restrict flow more.

    You indicate that further RO membrane fouling has an effect to reduce the permeate flow rate. I would have to concur. More pressure should squeeze more water through the membrane to a certain point, but would also begin to foul again, and sooner.

    Given that scenario, and if you could snap a finger and change out your HP pump to one that doubles the feed flow rate for the same pressure - would you expect any significant change in the permeate flow (doubling the feed flow, keeping same membrane and using the same operating pressure) ?
    To some extent. The Dow guy I talked with said increasing the flow away from the mb would reduce the fouling rate....this is more gallons through the flow meter of gallons pumped or circulation but it would not neccesarily increase my permeate flow.

    One needs to remember we are not using this mbs as originally designed. What we want is the throw away product for their original design. This are desalinization mbs. So when we want more sugar we are really looking at decreasing the concentrate flow to remove more water for discard. For a water plant they just pump more sea water through the mb and it is at no appreciable cost. For us it is more water that we need to pump back through the system to get rid of.

    But one could make a case for a large pump on a VFD that you could press B and the pump will spin at full rpm and flush the mb of lodged sugar. Drives for small pumps are in the $150 range and would work well for that purpose. One could also adjust the drive to adjust pressure. As far as that goes with a bit of wiring and pressure transducer one could make the unit adjust its own speed to get the most out of a run cycle. Add in a sugar meter on the permeate and if sugar were to pass then it could do an auto flush cycle.

    But now we are getting out of our budget perameters for many people; but the options really are all the way to a unit turning on and off as set by the operator and all one would need to do is manually change filter cartridges...set of several so that if output pressure dropped the unit would switch to a new filter housing by way of elec valves.

  2. #22
    Join Date
    Jan 2015
    Location
    Kirksville, IN
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    Sounds complicated,

    The intent was to get advice on the tradeoffs of designing in higher flow rates. It sounds like it's pressure increases that increases permeate flow. Using a higher volume pump and/or causing more needle valve restriction are ways to design in more pressure. In either case, the flow rate doesn't directly cause permeate to happen - its the resulting presssure that affects flow rate.

    I wanted to better understand the alternatives for selecting pumps for available membranes.

    The flow rate also is important because a higher flow rate is the mechanism to sweep membrane pores to avoid fouling. I am hearing that 2-3x the rated flow rate is a good decision as long as it is still less than the max spec flow rate.

    And a third consideration is to choose a right sized low pressure pump that can run continuously and is able to push through a prefilter and also keep the high pressure pump from starving.

    Then, to do all this for the desired processing capacity.

    I also want to operate only on 110V.

    I think I have found a combination: filmtec 2521 RO filter (for its 13 pH cleening limit) with a procon 215 high pressure pump and an Aquatec 55x2 low pressure pump. Aquatec 55x2 can contiuiously output ~20psi in the ~3.3-3.68gpm range. Procon pump flow rate can be adjusted by needle valve/etc to output upto 250psi. All this should process 120gallons of sap from 2% to 12% in ~3 hours.
    Last edited by Wizbi; 10-03-2015 at 04:30 AM.

  3. #23
    Join Date
    Mar 2016
    Location
    Auburn, OH
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    Hi Wizbi -

    I am also a small producer and have been using a small 4 x 150 GPD RO that was built using Hodorskib's design. We have been at 100 taps and are goiong to about 150 this year. The RO we have can't keep up and I was very interested in the questions you raised several years ago in this thread. Did you ever build the RO you seemed to have decided on and, if you did, how dos it run? Are there any things you did that you think work well and are there any things you would do differently?

    Thanks
    - Rich
    99 Taps with three other guys
    Homemade 4x150 RO
    Leader half-Pint pan on an oil tank arch

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