Advantages of Continuous Distillation

By Larry Taylor

Though there seems to be a lot of confusion and misunderstanding about the advantages of continuous distillation, as well as how it works, how expensive is it, etc., it is much less complex than one would think. The continuous tag implies that the machine never gets turned off. That further implies taking on a second or third shift just to feed the machine. Yay! More overhead. Just what a small, newly minted start-up company needs. Right? Nooo.

And then there’s all the piping and weird heat exchangers, slurry tank, mash cooker, huge fermentation tanks, product holding tanks, pumps… the distilling equipment list goes on and on. But that is to be expected when a distillery is ramping up production.

What if you could incorporate an inexpensive continuous still that could be run in batch mode with your current cooking capability? What if you could feed your still with 25 or 50 gallons of beer like a recipe development size kettle charge? Or feed 300 gallons of beer and either volume would only gobble up about 10 minutes to bring the still online and producing product in the same amount of time for either volume? Well, we’re here to tell you that this is indeed possible!

Batch vs. Continuous Distillation

There are pros and cons to each type of system. There are likely several myths, too. Let’s start with some basic ground rules for choosing a batch kettle for some background understanding about this debate. Firstly, I’ll mention as I have in another article that unless you have some very favorable tasting room laws for cocktails and bottle sales out of your distillery, it can be very difficult to be profitable with a kettle that’s much smaller than a 1000 liters (264 gallons). The larger kettle will provide more bang for the buck. Once you get your business rolling along you might consider putting a dedicated stripping still into service in an effort to keep up with demand or prepare for future growth.

So let’s say a 3000L stripping still is what you’ll choose to pair up with your 1000L spirit still, and you want to have the capability to run both stills simultaneously. That is a total of 4000L, and you’ll prefer no less than a 1-hour heat up time for either kettle. We can estimate that to heat each kettle we will need 240 BTU for every liter of kettle charge volume. So, 960,000 BTU. Let us call it a cool million.

That sounds expensive, ay? Ok, the minister of finance is not happy with the quote for a million BTU steam boiler, so we’ll have to settle for a simultaneous, 2 hour heat up rime. So, 477,400 BTU. Let us call it an even 500,000 BTU. Or a 15HP steam boiler. This for a two-hour heat up time. Let’s hold this thought about heat-up time and we’ll circle back to this point later.

If we ballpark a general rule of thumb, we can say that a typical stripping run will render approximately 1/3rd of the total kettle charge. So, a 3000L kettle charge of beer will render approximately 1000L (960 liters @ 25% aggregate ABV) of low wines. If we collect our stripping run at 100 liters (26.4 gallons) per hour, the stripping run will take about 10 hours after heat up to complete.

Let’s quickly summarize this segment: 

3000L of 8% beer will take 10 hours after heat up to render approximately 960L of 25% ABV low wines.

Onto the spirit run:

Now we’ll charge the spirit kettle with 960 liters of 25% ABV low wines. If we collect 160 proof (80% ABV) at 40 liters per hour (after heat up) the run will take 8 hours to complete, and we will have rendered out 300 liters of distillate.

If we assume that an optimistic 70% of that distillate (after cuts) is worthy of a bottle, we will have produced enough spirits to fill 560/ 750ml bottles @ 40% ABV. Or, 46.67 twelve 750ml bottle cases. Or, 3.35 barrels filled at the end of no less than a 10 hour day (after a 2-hour heat up and before clean up)  babysitting both stills. 

Summary:

• Very likely a 13 or 14 hour day to collect 3.35 barrels of useable distillate.
• Two distillation systems required to maintain a production schedule of 3.35 barrels per day.

About the StillDragon Continuous Distiller

Let’s start with the myth. One of the big complaints about continuous distillation is that the distiller cannot make “cuts” on a continuous on a system that is continuously fed. This simply is not true. What is true is that cuts cannot be made on a system that is set up strictly as a CM (cooling management) product collection system. But if set up as an LM (Liquid Management) for product take off it is not a problem to make cuts. The LM product collection pulls product off at the desired plate level in the form of liquid rather than vapor as done with VM (Vapor Management) product collection. LM product collection allows any vapor in suspension at that plate level to travel further up the column to be bled off as “heads”. 

As for tails, the StillDragon Continuous Distiller also employs a dephlegmator used as a pre-separation unit at the base of the spirit column. With precision temp control, this heat exchanger is able to hold back the “tails” constituents and prevent them from entering the spirit column. Once the tails liquid level accumulates in the re-boiler, They are automatically pumped back to the beer well to be run through the stripper column again. This acts to strip remaining alcohol, boost abv, promote better column behavior, and help form carboxylic acids that can enhance the flavor profile in the finished distillate.

Heat up time for the continuous still is just a matter of minutes compared to the batch kettle system. The 12” continuous system heats up and is producing distillate in 10 minutes for example.

As for actual processing speed, the 12” continuous system is capable of rendering 32 gallons of finished spirit in 1 hour. No! This is not a typo. That’s 256 gallons of finished product in a single 8-hour shift. How long did we say it would take that batch system to produce this much finish product with the same amount of heat input? 

• Batch System: 13-14 hour day/ 177.55 gallons (flavored spirits)
• Continuous System: 8-hour day/ 256 gallons (flavored spirits)

To be clear, that is a 45% increase in utility efficiency and a 135% increase in man-hours/labor efficiency! Unless you’ve been involved with Bitcoin, it is extremely difficult to get that kind of return on investment if you see my meaning? 

Advantages of Continuous Distillation… in a Nutshell

Distillation has always been about economy of scale. And if you really want to improve upon your margins, get home in time for dinner with your family, have more time to market your finished product, and of course, have the ability to produce more product at a faster pace (if that’s what you are shooting for), continuous distillation is the way to your future. Stop wasting your potential profit and enjoy a better quality of life: the advantages of continuous distillation are worth it.

A StillDragon Continuous Distiller can be sized according to your current needs to give you more flexibility to scale up production as your distillery gains traction and grows. Why handcuff yourself to a batch kettle that will require more man hours to operate for the same yield? StillDragon can build for a live steam feed or for a small, jacketed re-boiler.

Let StillDragon help you design your distillery buildout. Call the office Monday through Friday (8 am to 5 pm Eastern Time) at 561-903-4689 or email us at info@stilldragon.com. We’ll get you pointed in the right direction so you can start capitalizing on the advantages of continuous distillation.