Caustic shots?

[Stefano]

Hello,
I'm wondering whether anyone has experience with a fermenting tank cleaning technique referred to as "caustic shot" by which, without pre-rinse, a 2% cold caustic solution is used in 1 hL or so "shots" which go to waste (caustic is not recirculated to avoid problems involved with a CO2 rich atmosphere), followed by 10' rest and then followed by another "shot" and so on until the solution at the tank outlet is clear. The chemical guy says that this technique is more effecive than recirculation and that the volume of caustic used is lower costing less. I've never tried this and my worry is that, although effective with a small fermentation ring such as that from lagers, it might not work as well with ales and a foam forming yeast which foams out of the CIP pipe for example.
I would very much appreciate your input.
Cheers!
Stefano

[dick murton]

I know this is common practice amongst the bigger European brewers and a few smaller (what we would call regional or family brewers in the UK - but still much bigger than a 50 hl unit for instance). However the point about the caustic is to remove 95% + of the yeast ring, and then finish cleaning with acid. This way, on big vessels, you use (so I am told) far less caustic than would be mopped up by recirculating though a CO2 atmosphere. Because 95% + of the acid will be recovered, for the big breweries at least, it becomes more cost effective. It also means that instead of using hot caustic for the whole of the clean, you use cold casutic pre wash and then cold acid - so big energy savings, less thermal stress on the equipment and far less risk of imploding vessels, eithr due to thermal contration when the inevitable cooling takes place, or due to CO2 mop up by the caustic.

Not sure what the breakeven size would be as you have to balance simplicity of CIP set build and control against reduction in chemical and energy costs. You probably use more water as there is an extra rinse.

The volume of caustic is whatever is required to ensure thorough wetting each burst delivery, so take the 1 hl with a pinch of salt as it depends entirely on vessel and piework size.

[Stefano]

Cheers Dick,
I'd be interested in your opinion on the efficacy towards a fermentation ring extending to the whole fermenter ceiling and on the sprayball shaft as well?
I guess that if were this the case one could look at using antifoam or reverting to a non-head-forming yeast.
What do you think?
Cheers
Stefano

[gitchegumee]

Hey guys! I'm a bit confused. Wondering about these advantages. If using a non-built detergent, but plain caustic, then I don't see much savings. Caustic is really cheap, no? And why would we CIP in a CO2 atmosphere? Why not vent the fermenter? Unless it's absolutely huge, I guess. With cylindroconical fermenters, seems like the detergent volumes would be very small to recirculate. And energy savings via hot vs. cold? Couldn't you do this without the "shot" technique? I currently use Ecolab Advantis 210 alkaline detergent at barely warm temperatures. Maybe 30C. Works great. Same with PBW. I don't like to use hot detergent/acid solutions.

[dick murton]

I suspect there is no major advantage to using caustic pre-shots with a small brewery, but once you get up to FVs of a couple of hundred hl capacity or bigger, they take so long to vent fully that the time saving in not having to vent becomes important, as well as the cost of dumped caustic vs reclaimed acid. If you think about it, 22.4 litres CO2 (1 mole) will react with 40 grams (1 mole) dry caustic (i.e. not made up into any form of solution). The energy savings become much larger as well - no heating steel and refrigerant. And the additional cost of kit for a micro will become prohibitive. So for something under, let's say 50 hl tanks, I would stick to simplicity and use only caustic. As I said before, there must be a breakeven point, but I have never costed it, but simply suspect it will be where the vessels are big enough to require (not just a beneficial nice to have) half decent automation.

And some breweries I have worked in top pressure the FVs with CO2 during emptying, so the complete FV is full of CO2 prior to cleaning, not just the headspace volume of say 20 %

Re the other comment about will it clean the whole vessel surface OK - the simple answer is yes providing the spray head achieves full coverage. If the head doesn't reach the complete vessel surface area, then it doesn't matter what you are using - it won't get cleaned.