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Thread: cleaning heat exchanger

  1. #1
    Join Date
    Mar 2003
    Location
    Nashville
    Posts
    691

    cleaning heat exchanger

    We keep having problems with cleaning our heat exchanger. I've pulled it apart several times the past year, only to find trub and grain husks trapped between the plates. We have a Mueller HX with a criss-crossing herringbone pattern. At all of the points of contact between the plates, there always is small pieces of hop particles, trub, and grain husks trapped.

    We clean in the reverse direction from normal flow. We've used strong concentrations of PBW or caustic. We clean it for at least 30 minutes after every single brew.

    We know it's a problem because we will have the occasional forced wort test come up positive after 5-6 days. But I can't figure out what else to do to get the HX clean and sanitized. We have been sanitizing with either 200 F water for at least 30 minutes, or chlorine dioxide. I'm going to switch to peracetic acid next, after we completely tear down the HX and replace all gaskets. But I'm worried that our cleaning procedure is not working.

    Does anyone have any suggestions as to how to get these hop and trub particles out?
    Linus Hall
    Yazoo Brewing
    Nashville, TN
    [url]www.yazoobrew.com[/url]

  2. #2
    Join Date
    Feb 2003
    Location
    Boise, ID
    Posts
    233
    The heat exchanger cleaning velocity should be at least 1 1/2 times faster than the process speed. If your wort valves are wide open when cooling in, you may try hooking up a bigger pump for the cleaning cycle.

  3. #3
    Join Date
    Oct 2003
    Location
    Santa Rosa CA USA
    Posts
    962
    If you could prevent chunks from getting in your HX then you would be far ahead. I had some luck with recycling the beginning of cooling back to the kettle which had a bunch of trub-exactly for this reason. Perhaps a kettle dam or other method would get you cleaner wort.

  4. #4
    Join Date
    Jan 2009
    Location
    San Francisco, California, United States
    Posts
    101
    Try back flushing with hot liqour in the reverse flow, followed by caustic in the forward flow. By running your caustic the same direction as your beer you should create the same turbulence patterns and hit all the same areas.

    Also we have recently started using Leracept-O in our caustic cycle. It breaks down hop oils and resins, helps for us.

    good luck.
    Kushal Hall
    kushal@goodbeer.com
    Speakeasy Ales & Lagers
    San Francisco California

  5. #5
    Join Date
    Jan 2004
    Location
    St.Louis->Tacoma
    Posts
    633
    I have found that restricting the out flow on the HX, creating a positive pressure in the HX, spreads the plates just enough to dislodge some of that crud. I will also at times pulse it, quickly opening and closing the out valve during cycles, helps knock stuff free too. Pulse it 3 times and leave it closed, look in the sight glass for floaties. Been using this method for years on different systems and HX's and it has always worked well for me.

    I like to run "kill cycles" too, as you mentioned 200°F + for extended periods of time. If your tests are coming out positive after one of these, i think you may need to look elsewhere for your contamination. Oxygen stone maybe..?

    BTW another tip for the O2 stone. If you run a HX cycle with restricted out flow (valve 1/2-3/4 closed) you can bleed your solution out through the O-stone too. -2 birds anyway...
    Last edited by Jephro; 05-15-2009 at 04:01 PM.
    Jeff Byrne

    12 year pro craft brewer *NOW available for hire...
    Auburn, Wa - for now

  6. #6
    Join Date
    Jun 2007
    Location
    Solon, IA
    Posts
    262

    Pulsing the HX

    I'm with Jephro on this one...pulse your flow and bleed caustic and sanitizer through the stone.

    When you close down your HX for the night, are you packing it with anything? Both PBW and Acid No. 5 solutions are really effective are breaking any crap down that builds up in between the plates. We sometimes get coriander stuck in there from our white ale, but that doesn't give us any sanitation problems. It would seem that you're having problems down the line. But that's just a thought.

    Good luck,
    Bill

  7. #7
    Join Date
    Jun 2003
    Location
    Louisville, KY
    Posts
    993
    Quote Originally Posted by Jephro
    Oxygen stone maybe..?

    BTW another tip for the O2 stone. If you run a HX cycle with restricted out flow (valve 1/2-3/4 closed) you can bleed your solution out through the O-stone too. -2 birds anyway...
    Also run the o2 feed hose.
    Cheers & I'm out!
    David R. Pierce
    NABC & Bank Street Brewhouse
    POB 343
    New Albany, IN 47151

  8. #8
    Join Date
    Oct 2002
    Location
    Tadcaster, Yorkshire, UK
    Posts
    1,078
    I'd be wary of shocking the H/Ex by routine planned pulsing, even though I agree with the sentiments and accept it undoubtedly works. Modern H/Ex plates are so thin that they easily crack due to the flexing under these conditions.

    So the first thing is to get your whilrpool (if using one) working properly, or installing some sort of coarse trap filter to keep out the big lumps. Some years ago we used to use hopstrainers, consisting of wire wound filters. I have no idea if these are available new any more, but they were pretty effective. And then, as previously stated use 1.3 to 1.5 x forward flow rate to back clean, using perhaps 3 % caustic.

    Don't forget that every time you open and close the H/Ex, you recompress the seals adn have to tighten up a little more each time, which makes th eproblem worse. Whih raises a question - are you tightening up to the correct dimesions, and using the correct sequence every time ? The supplier should have provided a set of dimensions and sequence for tightening up the compression bolts (assuming you have more than one)

    You should only need to open up every 6 months, or better still once per year, with the seals and pack dimensions being good for several years use

    Cheers
    dick

  9. #9
    Join Date
    Sep 2005
    Posts
    675
    Couple comments --

    200F water is hot enough to bake on any existing soil, preventing future cleanings from being effective. I'd limit the temp to 180 -- hot enough to sterilize, not too hot to bake stuff on.

    I'd also be sure to run an acid cycle after the caustic/PBW cleaning to get off any mineral deposits which can hide stuff from the next caustic cycle.

    And ditto on the source of contamination -- the 200F water should kill everything in the heatex, even if it's dirty, so I'd look elsewhere.

  10. #10
    Join Date
    Jul 2005
    Location
    Chandler, AZ
    Posts
    209
    What about one of these http://www.breweryparts.com/detail.a...ategory_id=142? The only thing that'd suck is pulling it off after each knockout to clean it.

  11. #11
    Join Date
    Oct 2002
    Location
    San Luis Obispo, CA
    Posts
    83

    Filtration Systems

    Depending on your flow rates, you could look into Filtration Systems bag filter housing. This would be installed inline prior to the Heat X- product inlet.
    This has proven very useful in a regional brewery, which uses heavy loads of whirlpool hops.

    This "Filtration Systems" is available through Scott Laboratories.

    http://www.scottlab.com/products/fil...requipment.asp
    Todd
    Think Tank Brewing Services
    www.thinktankbrewing.com
    todd@thinktankbrewing.com

  12. #12
    Join Date
    Oct 2002
    Location
    San Luis Obispo, CA
    Posts
    83

    Sock Screen Gaskets

    Gabe,

    The surface area to volume ratio would be too small for this application. You would most likely blind the screen and have to break down and re-sanitize your entire brewmain. We sometimes had to do this with the Filtration Systems product and it was approximately 3' High X 6" Diam.
    Todd
    Think Tank Brewing Services
    www.thinktankbrewing.com
    todd@thinktankbrewing.com

  13. #13
    Join Date
    Jul 2005
    Location
    Chandler, AZ
    Posts
    209
    Quote Originally Posted by Todd
    Gabe,

    The surface area to volume ratio would be too small for this application. You would most likely blind the screen and have to break down and re-sanitize your entire brewmain. We sometimes had to do this with the Filtration Systems product and it was approximately 3' High X 6" Diam.
    I had suggested it in case the problem was in fact an occasional husk that was passing through (I can't imagine there should be too many in the hopped wort). In my system, there's no dam but I do have a screen that's about 1.5' high by 6" diameter, and if I'm careful with my knockout procedure, there's no trub to be seen in the screen after I'm done. In that case, I'm sure that one of those screened gaskets would do, but you're right that if there's a major problem, it will just blind and frustrate whoever is trying to work with it.

    Perhaps we should ask how so much husk and trub is making its way into the heat exchanger in the first place. Perhaps something should be seeked that will help make the trub pile tighter and the lautering regime should be revised to avoid any grain from passing through. Just another thought.

  14. #14
    Join Date
    Jan 2006
    Location
    Lawrence, KS
    Posts
    218

    Larger strainer a possibility

    We use a strainer like this http://breweryparts.com/detail.asp?n...ategory_id=227 ahead of our HX. It is both effective and hard to blind. It has done a great job of keeping bits of husk and also threads from scrubby pads out of the HX.
    Steve Bradt
    Free State Brewing Co.
    Lawrence, KS

  15. #15
    Join Date
    Sep 2007
    Location
    McCall, Idaho
    Posts
    337
    Quote Originally Posted by sbradt
    We use a strainer like this http://breweryparts.com/detail.asp?n...ategory_id=227 ahead of our HX. It is both effective and hard to blind. It has done a great job of keeping bits of husk and also threads from scrubby pads out of the HX.
    We have been using the same strainer and have been pleased with its performance as well.

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