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Cleaning Heat Exchanger

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  • Cleaning Heat Exchanger

    Hey All,

    I'm currently working at a brewery using a 61 plate single stage Thermaline heat exchanger. It's the first place I've worked where they need to break down the plates after every brew to clean it out properly. For those of you who need to do this, I'm wondering about your experience. Our brewhouse has no filtration or hop dam, and generally we got a lot of hop material stuck in the plate grooves. After every brew we would back flush and water hammer with a hose connected to the tap. On top of solid material we generally had a decent amount of wort left in the unit post-flushing.

    We recently purchased an inline strainer from GW Kent to help lower the amount of organic material getting stuck in the plates which we hooked up with a T-manifold at the wort in port. After our last brew, I hooked the heat ex in line for a CIP on our kettle, and pumped full bore for our caustic and acid cycle, again water hammering occasionally. Rinses in between cycles with 165 degree water looked like we were getting clear water through the heat ex. I broke it down today to see how well it worked, and we still had a decent amount of hop and protein material stuck between plates. Not only that, we still had A LOT of wort that dripped out as I disassembled the unit.

    I guess I have a few questions. For those of you who do NOT break down your heat ex every time, when you do, do you notice you have a fair amount of material between the plates, and do you still have wort that stays in the unit? In past breweries I've worked at, we would break down the heat ex about once a year just to check it, but we never had issues with infection, we always left it packed with caustic or acid, and would run sani through it prior to knock out. Is this an issue of tightening the screws more or less? I can see how solid material could still get stuck in there, but the fact that wort is still present is puzzling. Are we not tight enough and it seeping to the water exchange side? Or are we too tight where it's creating exit points to the water side? They've been taking it apart every day for the last 3 years, are the gaskets just getting worn and need to be replaced?

    I do not want to keeping tearing this thing apart if possible, its a pain in the ass, and my back doesn't like it very much either. I'm also a little surprised how much organic material stays in the unit, its definitely small enough to pass through the grooves, and I would have thought a long caustic cycle would have helped break that down even more, but it's clearly from knock out and not from the CIP cycle, our kettle cleans up pretty well with a spray out after a boil. Any advice would be greatly appreciated.


  • #2
    Firstly, you shouldn't have to strip down after every brew - a few times a year at best - there have been discussions about the strip down frequency - I am on the side of only stripping down once, perhaps twice a year - in other words planned checks only. I have been used to once yearly checks only.

    Secondly in order to achieve anything like this you must restrict the amount of crap that passes from your kettle / whirlpool. That unfortunately is another discussion, but check out threads about whirlpool design, hop strainers etc. Once stuff goes in, it is a pig to get back out.

    Now the heat exchanger. 61 plates is meaningless on its own. The critical thing is the design flow rate for wort, temperature in, and desired temperature out, which then determines the cold liquor flow and temperatures - aiming for cold liquor about 5 deg C cooler than the wort out temperature is a good starting point, and a liquor to wort ratio of about 1.1 to 1. So that determines the number and design of plates, and the wort flow rate.

    CIP flow rate, back flush flow rate - 130 % to 150 % of design forward flow rate - 2 to 3 % caustic not uncommon. Just dribbling tap water through is not going to flush any trapped rubbish out. Use cold water to backflush initially to reduce the cooking on effect of hot water. Acid clean the wort side periodically, or perhaps have an acid cycle following the caustic (I believe some people have had good success with acid first, then caustic - but I am old fashioned and caustic first at the right temperature and flow has always worked for me) and acid clean the liquor side periodically to keep efficient temperature transfer.

    So, key points - stop the rubbish getting in, back clean with 130 - 150 % of design forward flow rate. Resize if chiller too large, which I suspect it might be as you don't complain about blocked up chiller stopping wort flow in the middle of the run.


    • #3
      I would think you have probably over-compressed the gaskets. There is usually a minimum and maximum spec on the total width of the heat exchanger from backplate to backplate. If you are narrower than the minimum spec, you probably have over-compressed the gaskets, and the plates are touching. Where they touch, hop particles will get wedged and will never completely come out, no matter the direction of flow of your caustic. We had this problem with an older HX.

      You should take a sanitary sample of wort after the HX for every brew. If it shows signs of growth or pH change within a few days, you most likely have an infection in your HX.
      Linus Hall
      Yazoo Brewing
      Nashville, TN


      • #4
        Thermaline Plate Heat Exchanger maintenance videos

        Check out Thermaline's plate heat exchanger maintenance video series for a walkthrough of taking your machine apart and cleaning it.
        Thermaline, Inc.
        Office: 253.833.7118
        Toll Free: 800.767.6720