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  • Caustic concentrations

    Hi all,

    In trying to optimize our use of chemicals at the brewery, I've been reading a bit of research on the topic. Apparently, for cleaning CCT's, a solution of 1% NaOH might be enough to get it clean, if a proper pre-rinse has been executed.

    I was wondering: what concentrations of caustic does everyone use for different parts of the brewery, in particular:

    FV's
    heat exchangers
    bottling line

    and with which frequency are they cleaned with caustic and acid? And why?

    At the moment, we flush FV's with hot water, then pre-rinse with about 0,5% caustic (5 min cycle), then do our actual caustic cycle with 2% @ 70 degrees celsius, rinse with water, then PAA 0,5%. This same SOP goes for all in the brewery, minus the caustic pre-rinse.

    I'd like to get the amount of caustic used down to a minimum, whilst keeping the quality of cleaning high.

    Thanks & cheers,
    Allard

  • #2
    Try adding an oxidizing additive. However the cost math might come out the same, unless your motivation is more environmental.
    Brewmaster, Minocqua Brewing Company
    tbriggs@minocquabrewingcompany.com
    "Your results may vary"

    Comment


    • #3
      Cleaning is a function of 4 main factors -

      temperature = up to about 85 C with caustic, the hotter the detergent is, the quicker more effective the cleaning is

      Physical action - ditto - so sprayballs which rely on drenching have very little phsical impact, and the cycle time will be longer than for a high pressure cleaning head. Rotary slot sprayheads are somewhere in between.

      Time - the longer, the better the cleaning action

      Chemical concentration - the higher the concentration, generally the better / quicker the cleaning.

      So you could actually be hitting the sweet (optimum) spot at the moment with whatever those parameters are. But it is unlikely.

      So, FVs - 1 - 1.5% formulated caustic and if hot 60 - 65C, 20 minutes, though you may well get away with 15. 70 C shouldn't be a problem

      Heat exchangers - as above - but reverse flow cleaning at at least 100% of design flow, up to about 150% - any faster then you are wasting energy and risking over pressurisation and damage, mainly to the gaskets.

      Unless you are saving the main caustic for re-use, I wouldn't bother with the sacrificial caustic rinse. And I would forgo the waste of thermal energy by using a hot pre-rinse.

      Bottling line - again, as FVs

      You may well want to consider a regular or at least periodic acid wash for all of these, particularly if you have very hard water HNO3 / H3PO4 mix normally

      I have never used PAA that strong, running at 0.25 % but if this is the only way to get good micro, then no harm, but possibly a little unnecessarily expensive at 0.5%.
      dick

      Comment


      • #4
        ab

        I've worked quite hard to optimize our usage to get best cleaning results without wasting caustic. A 3% caustic solution at 60C with the addition of .5kg Sodium percarbonate in a 100L solution is what we use. I like to clean our fermenter at the same time as the centrifuge (outlet goes to sprayball) since it will remove all solids and keep the caustic solution clean not clog our sprayballs. With this method there is no prereinse at all. 15 minutes results in super clean vessels. It is valuable to use a caustic test kit. I've found that even a tiny amount of residual CO2 weakens your caustic. For the sanitizer a .2% solution of PAA results in about an 80ppm concentration which is highly effective (I would highly recommend the LaMotte test strips; easily purchased from Amazon).

        Cheers,
        Mic


        Originally posted by Allard View Post
        Hi all,

        In trying to optimize our use of chemicals at the brewery, I've been reading a bit of research on the topic. Apparently, for cleaning CCT's, a solution of 1% NaOH might be enough to get it clean, if a proper pre-rinse has been executed.

        I was wondering: what concentrations of caustic does everyone use for different parts of the brewery, in particular:

        FV's
        heat exchangers
        bottling line

        and with which frequency are they cleaned with caustic and acid? And why?

        At the moment, we flush FV's with hot water, then pre-rinse with about 0,5% caustic (5 min cycle), then do our actual caustic cycle with 2% @ 70 degrees celsius, rinse with water, then PAA 0,5%. This same SOP goes for all in the brewery, minus the caustic pre-rinse.

        I'd like to get the amount of caustic used down to a minimum, whilst keeping the quality of cleaning high.

        Thanks & cheers,
        Allard

        Comment


        • #5
          Thank you for your replies.

          Originally posted by Ted Briggs
          Try adding an oxidizing additive. However the cost math might come out the same, unless your motivation is more environmental.
          My motivations are financial and environmental. Mostly environmental, but to get the higher-ups on my side, also financial.

          Originally posted by Mic
          For the sanitizer a .2% solution of PAA results in about an 80ppm concentration which is highly effective
          Originally posted by dick murton View Post
          Unless you are saving the main caustic for re-use, I wouldn't bother with the sacrificial caustic rinse. And I would forgo the waste of thermal energy by using a hot pre-rinse.
          The idea is to reuse the caustic until unusable because of NaCO3, but I think you mentioned in some other thread that NaCO3 buildup is hardly a thing when pre-rinsing with caustic?

          Originally posted by dick murton View Post
          I have never used PAA that strong, running at 0.25 % but if this is the only way to get good micro, then no harm, but possibly a little unnecessarily expensive at 0.5%.
          That's interesting, I'll check it out. Honestly always was told that 0,5% was a minimum for PAA, so we never did otherwise. I see that Mic also suggested this.

          Comment


          • #6
            OK, so this is going back a good few years, and using large (1000 and 2000 hl) FVs - but the principle applies to all sizes

            We used to have a recovery CIP system, using cold, recovered rinse water pre-rinse - where the water was recovered from post detergent and post sanitiser washes (before the days of PAA - told you it was a few years ago!!) This had small residues of caustic in it, though it varied from clean to clean - and sprayballs - which really didn't do a lot apart from wash off the loose yeast and beer residues - which could be quite substantial, certainly enough that you wanted a pre-rinse before the detergent.

            This was then followed by a nominal 1 - 1.25% caustic solution - 20 minutes at 65 deg C at CIP set outlet. After a few vessel cleans, we had to dump ALL the detergent tank as the caustic was made up using a conductivity probe as controller, and was by then up to about 5 % caustic, due to the conductivity buffering of the carbonate and bicarbonate.

            After what were technically successful cleaning trials using acid detergents, but at huge cost due to acid being something like 11 times the cost of caustic at that time, I introduced a sacrificial caustic wash, taking a volume from the main dilute detergent tank. This worked well, and we never had to drop the main detergent tank again due to mopping up CO2 and removal of the heavy soil by the sacrificial detergent cycle. I actually wanted to try caustic pre-shots, but our CIP set allowed use of either caustic or acid only for all FV tanks and mains.

            I would like to think that modern acid tank cleaning cycles owe a little to this process, but am probably deluding myself.

            I don't know what size your FVs and CIP set tanks are, but if we assume you have 20 hl FVs, including 5 hl headspace, after emptying the FV, and assuming you don't apply any CO2 top pressure, but simply allow air to replace the beer, you have 5 hl pure CO2 in the FV just prior to cleaning. A cold water pre-rinse really doesn't remove much CO2. A hot water pre-rinse removes a bit more due to expansion of the CO2, and subsequent replacement by air. Lets assume you don't hot pre-rinse, to save energy. 5 hl of CO2 at STP will neutralise about 60 litres of 1.5 % caustic.

            Hopefully that will give a little more food for thought on what option(s) would be best
            dick

            Comment


            • #7
              Originally posted by Allard View Post
              That's interesting, I'll check it out. Honestly always was told that 0,5% was a minimum for PAA, so we never did otherwise. I see that Mic also suggested this.
              Okay this was a lie. 0,5% of Oxonia from Ecolab is what we use, which isn't only PAA, which I just figured out. D'oh.

              So, believing Oxonia contains 49g/l PAA, we're at 250 ppm which should be on the high side but not that exorbitant.

              Comment


              • #8
                Not sure how many times I've posted this on ProBrewer over the last decade, but considering my old posts have been eradicated and the same questions keep coming up, I'll post it again.

                --

                Keep in mind your target PAA concentration should not change, but your usage rate will depending on your product. Most 15% PAA concentrates are the same price as the 5.0% and 5.6% ones. It is important to distinguish between usage rate and concentration, especially as the industry continues to move to stronger and cheaper PAA concentrates.

                I would target 150ppm - 250ppm of PAA for a no rinse concentration for most applications. The peroxide and acetic in these productsis not counted towards the usage rate of PAA. Your ceiling will be determined by oxidative off flavors from the PAA.

                You also cannot use PAA at above or below the EPA limits, which is likely 90- 500ppm. Believe it or not, I have seen recommendations from vendors as low as 65ppm for sanitation. A 0,5% concentration is going to chase everyone out of the building amd will get you shut down in an inspection. A 0,5% usage rate is meaningless without product concentration, but is in line with the weaker PAA products commercially available to achieve this range.

                For caustic, the usage concentration will depend on the formulation of the caustic. I recommend 0.25 - 0.75% NaOH for high performance products with added chemistry. The standard for raw caustic is 2-4% NaOH, and should include a chelator or some additive.

                For hotside caustic, adding 1000 - 1,500 ppm of peroxide (adjust usage concentration based on concentration of the peroxide additive) will greatly improve the performance against stubborn organic soils and is a great chlorine-free alternative to chlorinated caustic. This will work best at 160-180F / 70-80C. This can be agressive to lower quality gaskets. Percarbonate can be used in place of peroxide for breweries small enough to be dosing powders by hand and where higher chemical costs are less concerning, however peroxide is cheaper and can be easily pumped. This additive should be added to the caustic solution and not the concentrated caustic.

                You can get a good indication of your caustic's level of additive by determining the amount of NaOH in it. Pure NaOH solutions hover around 50%. Anything near this concentration is likely plain caustic or simple chelated caustics (45-47%). As you add performance chemistry (detergents, etc), the concentration of caustic must decrease. Beware of salepeople who conflate usage concentrations with caustic concentrations.

                KOH can be used in place of a portion the NaOH to improve rinsability (if your caustic does not have rinse aids already in it) and to adjust the freezing point of the concentrated caustic. It is more expensive than NaOH and slightly less alkaline, but does not contain Sodium if you have effluent restrictions.
                -BC

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