Batch pasteurizing - thermodynamics question

[DancingCamel]

Looking at building a batch pasteurizer for pasteurizing bottles after filling. I'd like to mate it to a Meheen-type filler so that post-fill it keeps up with a speed of app. 25-30 bttls per minute. I'm thinking of using 3 vats (first is 30 deg C, second is 72 deg C, third is back to 30 deg C) and lowering the bottles in bins into each vat for a prescribed amount of time.

So here's the fun part. Each temp-controlled vat will have "X" volume of water. Each bin of bottles will have "Y" number of bottles (assume 330 ml bottles). The question is what ratio of water to beer do I need to bring the bottles up (or down) to the temp of the water at a rate of 25 bttls (8.25 ltrs) per minute?

Let's further assume that the water in the vats is being constantly circulated within each vat to assure even temp distribution and that the vats are temp controlled so that the water remains at a (more or less) constant temp despite the thermal mass of the bottles being introduced. I have also not yet determined the number of bottles per bin - only that the bins need to move through the process at a rate of 25 bottles per minute. Thus, a bin can contain 25 bttls but then it can only get app. 1 minute per stage so that it keeps up with the filling line. Or it can contain 200 bottles in which case it gets 8 minutes per stage, etc.

Lastly, let's assume that I am an accountant and not an engineer so I need a formula that doesn't require an advanced physics background.

OK. Let's have at it.

[ParishBrewingCo]

Good idea. Here are a few of my thoughts:

1.) Sounds like a lot of work. You will probably need an entire employee or two just to do the dipping. And that is a lot of heavy lifting for one person to do all day long. Something more automatic would save lots of aches, and probably $$ over the long run. It seems a small tunnel pasteurizer wouldn't be that much harder to build if you could find a used conveyor. Use the reservoirs you are already planning to build to hold your cold and hot water and recirculate to a spray head above the conveyor in zones. Get a VFD for the conveyor motor and you have ultimate control of residence time.

2.) You dont need any fancy engineering formulas here. You already have it figured out. It is about residence time at each temperature station. You can only keep each "batch" in a pasteurizer station until the next batch comes off the filler. If you're filling a case per minute, you will only have 1 minute to soak a case's worth in each station. Simple.

[DancingCamel]

Batch pasteurizing

Thanks Parish. What I'm trying to find is a way of doing this without slowing down the filling. If my "bin" contained 25 bttls then you're right - I have one minute in each stage to achieve my desired temp. Given that, the question is how much water do I need and at what temp to take 25 bttls from about 5 deg C. to 30 deg. If the answer is say, 24 liters (a 4-1 ratio) at 32 deg then it gets more interesting. If that scales up linearly then I can do 8 cases at a time in which case I need 192 liters of "bath" water for each stage. What i was thinking about building was a frame with an I-bar overhead and hoists to raise and lower each bin. Stage 1 is done, slide the hoist down to the 2nd bath and lower in, etc. But again, I need the "magic bullet formula" to figure out a thermal transfer rate so that I don't slow down the filling.

You're right in that I'd need an extra person unpacking from the filler and loading into the bins but the lifting would be done by hoist.

As far as tunnel past - I don't think I have the space.

Any help would be greatly appreciated. I'd be willing to trade tax/accounting advice for the right answer

[einhorn]

Ever think about a pallet pasteurizer?

[DancingCamel]

Pallet Pasteurizers

Any idea of cost of a pallet pasteurizer? Recommendation for manufacturer?

[einhorn]

A quick Google seach showed this.

I do not know this manufacturer. I worked for a juice complany in Germany which used something similar for NR bottles, but I have forgotten who produced it. Sorry I couldn't be of more help.

Good luck!

[gitchegumee]

Most pasteurizers have some sort of heat economizer that uses the heat from cooling the bottles to warm those going in. Why have bath #1 separate from bath #3 and have all that energy (both heating and cooling) go to waste? Pasteurization is all about probability, temperature, and time. Read up on PU and other issues regarding this topic in "Beer Packaging" by MBAA. Sounds like an expensive (labor, energy, capital) undertaking. Good luck!