Large Scale Recirculating System 500L +

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Hi Guys,

Ive scored 4 large SS304 pots, 0.9m diameter x 1.2m high am im planning on building a big ass brew system out of them.

Ive got a couple of questions about design and lautering i wanted to run past everyone and see what options are actually available vs steaming ahead with a build reminiscent of a typical home brew setup and causing myself a headache in a few months time when i fire it up.

My original plan was a 3V Herms system with the Herms being in a separate smaller vessel for efficiency, however my calcs lead to believe ramp time with this will just be ridiculous unless i pack in 36KW+ into the Herms loop. The other options would be to use the kettle as a Rims system or K-Rims and use the elements already installed (ULWD of course) to ramp.

Im also slightly concerned about compacting the grain bed at this scale. Assuming 75% efficiency for the following %ABV beers on a 500L batch would result in a false bottom loading of:

5% - 100kg - 157kg/m2
6% - 120kg - 189kg/m2
7% - 140kg - 220kg/m2

This seems ideal considering that a "rule of thumb" is 140-250kg/m2 loading. But this would be for a pro brewer setup without recirculation, except prior to sparge to clear the grain bed. From the info i have read a wort velocity of 7-11mm/min seems a good rate to start the runoff without compacting the grain bed.

If i were to go with a Herms or Rims and recirculate, on this system with the tanks shaped how they are would result in 1L of liquid occupying 0.157cm of vertical space, so if you were to run off 5l/min that would be 7.9mm of wort per minute moving through the grain bed. Not exactly prime recirculation rate inorder to ramp temperature. Once you've set the bed the velocity could be increased quite a bit and avoid channeling etc, i just dont know to what extent as my only experience is HB and im pretty sure things dont scale linearly.

Just wondering if anyone has experience with recirculation at this scale, is it possible, potential issues, tell me its a terrible idea and its not even required?? For whatever reason, probably because my first system was a Herms and i do step mashing quite a bit, especially with raw wheat i seem to be attached to the idea of a similar system just at a larger scale.

Im still toying with the 3V system but just doing single infusion mashes while heating sparge water in the BK to 78 before transferring to the HLT to sparge. i would then recirculate at a slow rate to clear the grain bed before sparging. Cant see a problem with this.

Another hair brained idea is to make 2 x 2V K-Rims systems, though this would result in a lower efficiency, requiring more grain, and a greater loading on the false bottom meaning a greater chance of compacting the grain bed.

Thanks for the info, ill be sure to post up progress as this thing proceeds.

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Sounds like a bunch of fun project.
Couple of things that might make our life easier.
If you have a fairly deep grain bed (think higher kg/m2) your crush becomes really important. You can get much higher flow rates through a grain bed that is well cracked (large husk fragments and lots of "kibble" rather than flour) than you can through what most home brewers would consider fine enough. The extreme end of this is the "Floating Mash" where the grain is barely touched by the mill and there is enough air trapped in the corns to make it float rather than sink onto the floor. Tradeoff is that it takes longer for the sugars to migrate out of the kibble, rush your sparge and your efficiency will go down the toilet. Think 2 hour sparges, minimum, a modern "high speed" industrial lauter will take 90-120 minutes that's at 150-250mm beep grain loadings, that's where their +95% efficiencies come from.

Have a look at Wedge Wire as your floor material, it isn't cheap but its available in a huge range of forms, some that can carry very high loadings and still provide over 25% void in the floor, so lots of flow capacity. Not only that, you will get a very even flow across the whole grain bed. Worth investigating putting multiple outlets in the bottom of the mash tun to help balance the flow.

You may not need a rims/herms system, it is fairly easy to do hot (boiling) water additions to hit a couple of steps. Takes a bit more planning but the maths is pretty basic.
Mash in fairly heavy L:G in the order of 2.5-3:1, then pump up your boiling water from the bottom while you stir like buggery.
Not a bad idea to use the kettle to provide the boiling water, keep your HLT for controlled temperature sparge water. otherwise you would need a big HLT as well as MLT and kettle.

One more gratis - good insulation only needs buying once, but it pays off in every brew after that.
Using the same % ABV's as above:

5% - 100kg - 157kg/m2 - 0.33m high grain bed
6% - 120kg - 189kg/m2- 0.40m high grain bed
7% - 140kg - 220kg/m2 - 0.47m high grain bed

So not quite ideal. I checked the numbers before i forked out for these and figured that even though they're a bit tall and thin its still workable and at 0.9m diameter they should fit through doorways which is plus if i ever do anything with them.

Boiling water infusions are an option if stepping is required, im just hesitant to boil 500l twice as it will eat some juice. I guess ramping temperatures would take the same if not more as there would be less efficient heat transfer. One idea i had with 4 tanks was to use 2 as a double sized HLT with an overflow loop between them to balance the temperature. This would only be useful if it was ever used to do multiple batches and collect the HEX water for the next sparge. Too many options a this point.

Safe bet might be stick with a simple traditional 3V system, no recirculation and use the infusions as an option if needed.

If there is not option to circulate the mash through a HEX, what would be the best option to ensure you hit strike temps? Go a degree or two too hot with the hot water and have a cold water balancing valve inline to adjust as your mashing in or keep some spare boiling water to the side?

Nice tip on the wedewire, ill look into that.

Got any recommendations on insulation? i cant imagine it would need to be too thick as the thermal mass should hold temp pretty well. I have been thinking Formshield as its closed cell so should insulate against both conductive and refletive heat transfer but maybe ive been reading too many HB forums ;)
Welcome to the realities of commercial (sized) brewing. A few of the facts of life;
The biggest product in a small brewery is warm water (waste).
Energy will be one of you biggest costs, probably higher than malt or hops.
Professionals only count vessels that touch product, a HLT, MT, kettle is a two vessel system, even if you add a CLT its still a 2V system.
Like people who pronounce wort (sounds like wert) like a skin condition, you just know they are amateurs.

Looks like decent insulation although there are lots of choices. Good insulation is a great investment. A good mill can easily make 10% difference to your efficiency (I've seen over 20%), to put that another way every 10th grain bill is free!

Move up a couple of size steps and brewery design is all about moving energy around - you biggest controllable dependant variable.

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