A question on the number of plates required.

[trinacria]

So Im curious about the effectiveness/efficiency of the number of plates on a still. Now lets say I want to make vodka and I go with a larger still manufacturer, their set up will have 16+ plates. But if Im starting on a tighter budget and go with a component type set up, say the hillbilly flute or still dragon, I can apparently get by on making vodka with far fewer plates. Why is this? I get that more plates = a more pure distillate so it that it? The bigger systems simply produce a superior product in one run vs a smaller system requiring maybe two runs to get something comparable? Is it a scalability issue; bigger pot/more vapor = a need for more plates? Or, is it something else entirely and Im way off base/have a huge gap in my knowledge/understanding?

EDIT: Just to clarify I am not sold on producing vodka. In fact I'd say I'm 95% set against it. This is just something that, as I've been researching and drafting my business plan, I've been really curious about.

[seventh son]

Here's my take and I'm sure others will step in and correct me if I'm wrong: Making vodka is all about two things - achieving 95%, and achieving separation of heads, middle, and tails. To do each of these you need lots of reflux. A short column will require multiple passes to achieve 95% unless you slow it waaaay down by increasing reflux. As your run goes on, more and more reflux is needed to keep it at 95%. A narrow 3" or 4" column gives you a pretty modest flow rate to start with. Then the question becomes - can you build your business on the vodka production volume that a small still can produce? Do the math, you'll probably discover that making something (anything) other than vodka is a better choice if you are on a low budget!

[Sherman]

say the hillbilly flute or still dragon, I can apparently get by on making vodka with far fewer plates. Why is this?

You can't. This will require redistilling multiple times. The last distillation requires you to put really high proof alcohol in the still. This is not an issue with safety but with production costs.

If you have to distill 3 to 4 times to get vodka you are tying up equipment and time to the point that long term cost of production will exceed the up front cost of the proper equipment.

If you are making vodka, you will probably at least have to do a stripping run, and then a NGS distillation with a minimum of 20 plates, or a packed column with a 20 plate equivalent. There is a misconception that just because you are reaching 95 to 96% you are stripping all the flavor. The heads usually starts higher because of the lighter volatiles and then decreases to 95 to 96%. It takes a lot of alcohol to support a column of any size.

In order to produce NGS in a single run, the pot size has to be disproportionately larger than the column. To accomplish having enough alcohol to run NGS on a 8" 20 plate column, you would have to have a pot of about 1200 gallon to provide enough alcohol to allow that size column to remain at equilibrium for any length of time. The alternative would be 4 stripping runs on a 300 gallon and then a spirit run on a 300 gallon with a column.

I do have to say to anyone who is putting together a business plan, based on trying to utilize small, inexpensive equipment, you might want to reconsider how much operating capital you will need for the future, until you get into production and have sufficient sales to break even. If equipment expenses are an issue more than likely you are underfunded and heading for a disaster when it comes to operating costs. I find this to be the largest issue to success of the craft distillers. Starting too small in a state where you cannot self distribute or have gift shop sales will prevent you from getting into distribution. This is especially true in an ABC state such as Virginia.

[trinacria]

You can't. This will require redistilling multiple times.

This is what I sort of assumed and it makes perfect sense. I made the assumption that if a smaller set up (such as previously mentioned) were capable of producing 190 proof spirit in a single run that it would indeed be pretty well stripped of flavor. As this is apparently not the case then everything else (cost of multiple runs...) logically falls into place. I edited my original post to clarify that I am personally not planning on producing vodka but, as I've been researching various still manufacturers, this question did enter my mind. Thanks mate.

[Artisan Still Design]

you can hit 190 proof with 4 plates (very slowly though) from low wines, but it will still be chocked full of flavor.

there is a really good reason why large distilleries use 120 plates for continuous vodka production. its not to hit the right proof, or even for efficiency of extraction, but to strip the flavor out.

[Natrat]

All of this assumes that using many plates is the only way to achieve the necessary reflux to adequately compact the chemical sections of the distillation...but there is a reason for fractional processes as well. Having said all of that, I think Sherman was on the money with his assessment of the craft situation...and shows why there is a prevalence of NGS product on the market.

Steven, the plate size in a column is a direct relation to the column size. If one could increase the area of the plate without increasing the diameter of the column, theoretically, could enough reflux be achieved in a smaller number of plates? I'm asking because I am assuming that it is the total effective area of the plates/bubble caps in the column that affects the cooling/reflux of the vapor. That's what the practice of using packing or SPP suggests, anyway.

[smaug]

All of this assumes that the desired result is supposed to be as flavorless as possible? And if the desired result is not to strip out all flavor?

I have to say that Davin Sherwood makes the most amazing Honey vodka. Not at all devoid of flavor and character. His product is quite distinct and very much delicious.

Was it collected at 95%? I bet so.

Is it true vodka? His authority having jurisdiction says so.

He has created an identity rather than fall into line with some of the other 52 buzillion vodkas out there. Many of which are identical or nearly so.

[Artisan Still Design]

Natrat.

I would suspect that the fractioning is more a product of the condense/vaporize cycle within the column, running higher reflux will aid this, but more plates allow further temperature separation which in turn allows more distinct fractioning. so it is very much a both/and situation.

Larry, I think we can all agree a honey vodka, or a maple syrup vodka or any vodka that has a unique fermentation stock that's worth highlighting, will benefit by distilling through fewer plates, but still enough to push 95%. but for standard vodka, its generally accepted that you want minimal flavor. Carbon can polish out a certain amount of flavor, but more plates will do a better job.

[Natrat]

Steven, I think we need to sit down at some point and talk, but one more question for now...

The volume of vapor between plates interests me...I assumed that the height of plates was due to the need to possibly get your hands in there...for assembly as well as service and cleaning, but as I run through my calculations, I am seeing that there seems to be a minimum volume of vapor between plates to make it work efficiently. Is there any benefit to using a compacted plate setup near the base of the column, and then increasing volume as you go up? I can see already where there is an optimal ratio range between column diameter and distance between plates...and how that translates to number of plates, etc...but I haven't taken the time to plot the plate to plate vapor/condensate curve at operating temperatures.

I think I've got a handle on pot/vapor production sizing to column diameter (and volume) as well as condenser sizing...but I just think that there is a happy place somewhere between bubble plates and labyrinth packing.

Has anyone seen any unusual columns? I'd be very interested in seeing them...

[Artisan Still Design]

now we're getting into the math that took me a long time to figure out, some of it is intuitive as you have figured out, but some is not. My mathematical model was hard won, and I'm not willing to share it all in public. but if you like I'll answer PMs, at least yes or no answers. I don' have all the answers (far from it) but I do have some solid math, and I have some strong suspicions which seem to be proving out.

[Natrat]

I won't push :-)

I'm actually enjoying the math figuring right now...using this computer math stuff sure is easier than the poopy Reverse Polish I learned in college! Once I've got my own model hammered out, we can sit down over some hard-won self-made whisky and commiserate :-)

Meanwhile, I am having some fun with this still you designed...and sorry to Trinacria for hijacking your thread...!