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Ratios for mashing tank / still / fermenters


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I’m working to build a list of equipment for a business plan. My approach is to start with the still capacity, and then estimating the optimal capacity of the mashing tank, fermenters and low-wine receivers. The following numbers are based on my theoretical understanding of the whole process and observations in other small distilleries, I want to be challenged by people who own distilling equipment.

Assuming I’m working with a 400 litres pot still, I’m figuring a 1200 litres mash tank would be convenient since it’s a 3-for-1 ratio. A full batch of mash with this equipment would require approx. 1000 lbs of grain.

I’m estimating that this mash tank of 1200 litres would yield approximately 70% of its volume in strained mash ready for fermentation, therefore 1200 x .7 = 840 litres.

Assuming that a fermenter can be loaded at 75% capacity (leaving room for bubbling), I would require 3 fermenters of 400 litres each for instance (or 2 of 600 litres, but I hear that a smaller fermenters are best).

After the fermentation has been done, I would have 840 litres @ 8.5% abv for instance.

The beer-stripping run would yield 25% of the original volume (840 litres x 0.25 = 210 litres @ 40-50% abv). If my low-wine receiver has a capacity of 450-500 litres, I could do 2 beer-stripping run (for a total of 400-420 litres) ready for the spirits run.

Do these numbers make sense ? Thanks.

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Regarding your strip run math, you'll run into diminishing returns into the tails. You've got to weigh the cost of time and energy against squeezing out every last drop. 20% is probably more realistic at 8.5% abv. Check your yield - 840 liters at 8.5% abv is 142.8 liters of 50%, 178.5 liters of 40%, and that is only if you squeeze out every last drop, which you likely won't.

You need to take into account the volume of the grain vs your mash tun capacity. 1200 liters (317g) water and 1000 lbs of grain would require something around 2000 liters capacity. More realistically, if you aren't pushing for high yield, and you want to deal with a nice easy mash (and not a monster), you'll probably be doing something like 250 gallons water, 500 lbs grain, which should put you somewhere near the total capacity of 300 gallons, the only challenge is now you're dealing with much less than the original 8.5% you factored for (this isn't a suggestion, only an example). You can make your own decisions, but sometimes it's easier to just go bigger than deal with trying to get the highest yield possible.

If you are using the same still to both strip and spirit - you'll want to do more than 2 strips per spirit run - otherwise you are wasting time. Based on the 20% figure above, factor 4 strips to a spirit - depending on losses, lower than expected yields, etc, you might be able to do a 5-to-1

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Thanks for the input, I get from your example that the grain-to-water ratio for the mashing should be somewhere around 2 pounds per gallon of water. Would this ratio be dependent on the type of grain used, or is it pretty much the same ?

I hope you had your 2nd cup of coffee by now.

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Spitfire, do a search on the forum. There's a ton of data about how much grain to water people use, and their ratios. On a typical mash, the grain will increase the volume of the water by a third, or so. Well, more like a quarter, but I like to have space :-)

Your 3 to 1 ratio sounds like you plan to strip 3 days, run spirit one, and mash on the fifth. I'd suggest that you will probably be able to do 2 stripping runs in a day, and that a 6:1 mash:still volume ratio is more in line with a production environment on a one week cycle.

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