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  • DE Filtering Issues

    I'm looking for any tips or information about running a 2sq meter horizontal pressure leaf filter for filtering cider. I have been trying to figure out this whole DE filtering thing for months and I am about at the end of my patience. I've chatted with a bunch of people who all seem to tell me different things. The biggest problem I am having is DE in the cider, which made me think the bolt on top wasn't tight enough. I'm not convinced I'm successfully filtering at all. I have tried changing my precoat amounts, body feed amounts, and DE types. Any info would be appreciated! If anyone has photos of their filter screen set up that would also be helpful!

    Thanks!

  • #2
    There are a number of possibilities


    Check the system has been bolted together correctly and there are no leaks due to misplaced or missing seals or warped surfaces, particularly if your kit is secondhand.

    Overpressurisation can warp parts.

    Is the first precoat powder coarse enough?
    Are you putting enough on?
    Are you putting on a second precoat, normally of the same powder you use for bodyfeed?
    Are your flowrates as per manufacturers recommendations? If too slow, or too fast, you will get uneven flow across the horizontal leaves, and therefore uneven deposition of powders.
    Have you fully degassed the system, and are sure you are not pumping in air as well as the powder?

    I'm sure there are more, but those are the things I would look at first,
    dick

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    • #3
      All the points made by Mr Murton are correct. The screens have to be sound and without tear or defect and the stack bolt needs to be tight with no leak in the seals separating the screens. Once you've confirmed the filter is fundamentally and mechanically sound, you can develop a precoat and body feed procedure whereby you are using approximately 20-35 lbs of precoat per 100 square feed of surface area and an appropriate body feed concentration and rate developed in optimization trials. The precoat flow rate should be at approximately 2 gpm/square foot. It should take no more than 15-20 minutes to develop a sound precoat. If there continues to be issues precoating you can use a small amount of long strand alpha cellulose filter aid mixed in with the DE. These fibers will bridge most small imperfections allowing for a quick precoat and provide cake stabilization during pressure upsets. Many operators use FibraCel in their precoat as a matter of SOP. Lastly, as per the recommendations of Mr Murton, you must verify that the filter housing is fully evacuated of any air so as to assure equal distribution of precoat and body feed ruing the coarse of the filter cycle. Am new to this forum so don't know if the attached picture of a brewing filter precoat has come through.


      Click image for larger version

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      If there are any questions, please feel free to contact me

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      • #4
        Superb photo. Wish I had been able to get some that good.

        I assume it is simply the effect of using a very wide angle lens, but the cake looks a lot thicker on the bottom leaf than the top leaf, suggesting slightly low overall flow IF that is correct. But to be fair, I have seen far, far worse.
        dick

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        • #5
          Good call. Complements of the Apple iPhone 6+. You are 100% correct in that it does appear that the lower layers are substantially thicker. This was based upon the angle of the shot to prevent the flash from flaring out the shot! This was not the case in this filter, but often times you will find a thicker layer of precoat on the lower leaves, especially if the flow is lower than desired. This is due to the to the density of the DE and its natural tendency to want to settle out. This is why the precoat flow rate should be as high as the pump will allow into a totally vented, flooded housing. Even if there are slight variations from top to bottom, the goal is establishing a stable precoat on each leaf. I liked this picture as you can see both the top of the precoat as well as the depth. Thx!!

          Comment


          • #6
            Thank you for the advice and picture! A lightbulb went off in my head when you said the flow has to be high during the precoat, that could be why I am also seeing a huge amount of DE at the bottom of the filter. I also just tried cellulose for the first time yesterday during precoat and that seemed to help. At first I thought the DE wasn't coarse enough, bought coarser, then even coarser, still had the same problem. I have tried different values for the precoat and bodyfeed. The latest being 1.5 pounds cellulose then 2 pounds each of harborlite and hyflo for the precoat. The bodyfeed was 6-8 pounds Hyflo, I think this is too much, but when I talked with the guy from where we bought it he kept telling me I wasn't using enough during the bodyfeed.

            I'm going to try a higher flow rate during the precoat, and a smaller amount of DE during the bodyfeed.

            The other problem is there is still CO2 in solution so that might causing problems as well.

            Could someone send a picture of what their top bolt looks like, ours was shipped differently than it should be when it's being used.

            Thank you!

            Comment


            • #7
              I have also noticed that during filtration the pressure and air release valve on the top of the bell has water coming out of it, not cider. Makes me think that the cider isn't even making it to the top of the filtration screens? I'm in the process of filtering now, I let the flow rate during precoat go higher than usual. We'll see what it looks like when I break it down...

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