Beer Still Diameters and Distillery Capacity; It Is Not That Simple

The beer still at the new Bulleit Distillery is 42" diameter.

With all of the new distillery construction and existing distillery expansion going on, it is hard to get a handle on how much new capacity is coming into the industry. Distilleries can produce below their capacity, of course, but these days bourbon distilleries are making as much as they can, so questions of capacity matter.

Although not quite the same as the beer we drink, the fermented grain mash that goes into a still like the one pictured above is called beer, and the still itself is called the beer still. This still strips all of the alcohol from the beer. That vapor, which is still 20 to 30 percent water, goes to a second pot-type still called a doubler for a second distillation, to remove more water and 'polish' the spirit.

Many factors affect how much a distillery can produce. One of them is the size of its beer still. A beer still doesn't have to be a column (i.e., continuous) still, but that is what most bourbon makers use. Because they are so tall, still height is the dimension that seems to impress people, but the dimension that matters is girth, the diameter of the still.

In trying to assess the capacity of different distilleries, I have tried to base it entirely on still diameter but, of course, it is not that simple.

"The diameter of the column is a very important part of the maximum throughput, but it’s not the only thing," says Mike Sherman, Vice President of Vendome Copper & Brass Works, the primary manufacturer of stills and other equipment for America's whiskey makers. "Tray design (amount of open area in the perforation) and downcomer size (the pipe that takes the beer down the column from one tray to the next) play a huge part." Other factors include beer thickness, condenser size, and fermentation yield.

It is also not correct, as I had assumed, that two 36" columns would have the same capacity as one 72" unit, for example. "It is not the diameter of the column, it is the area of the column" that matters, says Sherman. (A=𝜋r²) A 36" diameter column has an area of 7.06 ft², so 14.12 ft² for two columns. A 54" diameter column has an area of 15.9 ft². So, technically, the 54” column can run more than two 36” columns as long as everything else is sized correctly.

It also matters how each distillery uses its equipment, in terms of hours per day, days per week, and weeks per year. Some run one shift per day for five days and have a six-week shutdown versus another that runs round the clock for six days per week and only shuts down for two weeks per year.

So still area is a better metric than still diameter for comparison purposes and it is only roughly comparable, since it doesn't factor in those other considerations.

There are no easy answers, dammit.