I do understand that continuous (column) stills are more efficient due to their throughput and non-stop feed of wash, but I would like to know whether repeated distillations ( I believe it is called rectification) in a pot still could produce neutral spirit with almost no congeners identical to a continuous still
Do/can continuous stills produce neutral spirit in a single run? or are they also rectified to get neutral spirit?
Our vodka stills have 20 plates so that you can do 21 distillations in one run. They are pot stills. They are not continuous. [email protected]
Reply:32 minutes ago, Southernhighlander said:
Reply:1 hour ago, whiskeytango said:
True pot? No plates? Easy. Fill it with 190 proof, run it. 190 proof comes out.
Take a token heads cut, maybe leave a little behind as tails.
Reply:14 hours ago, Silk City Distillers said:
Reply:21 hours ago, perfection said:
Reply:On 3/9/2020 at 11:22 PM, Southernhighlander said:
You can have plates (or packing) in continuous stills and in batch stills. The purpose of the plate (or packing) is to increase the enrichment or rectification.
Basically these plates emulate the repeated pot still distillations you suggested in your first post. I suspect this is why Southernhighlander said he can do 21 distillations in one run - 1 for the pot plus 20 plates. In a column the stages are simply stacked on top of each other rather than being separated in time (as they would be with repeated pot still runs).
The difference between a continuous still and a batch still is that (theoretically) all the strengths remain constant in a continuous still, but will change with time in a batch still. In a large continuous plant the columns will run 24/7 - always receiving the same strength feed and delivering the same strength product.
I have never seen a single *continuous* column capable of producing neutral spirit. Typically there would be at least 4 continuous columns in series to make neutral spirit. The first column is the stripper and it produces about 30-40 ABV spirit. The second column is a rectifier that will make "industrial grade" 95 ABV alcohol. Heads are removed from each of these first 2 columns.
The spirit from the 2nd column is diluted down to around 15 ABV with clean water and fed to the hydroselection column. This is an "upside-down" column and the product comes off the bottom and is taken to the final rectifier where it is enriched to 95-96 ABV.
Beyond these 4 columns there could be 2 or 3 more columns for low grade recovery, de-methylation etc.
You can (thousands of distillers do) make neutral spirit in a single *batch* still of the type described by Southernhighlander. The difference between doing it in a single column batch-wise and doing it continuously in multiple columns is that you will get a higher percentage of your alcohol out as neutral grade in a continuous setup compared with selecting only the best "hearts" from the batch still. It is of course far easier to run continuous stills using automatic instruments than it is to run a batch column.
Reply:On 3/17/2020 at 2:29 AM, perfection said:
Also, number of plates doesn't always equal number of theoretical plates. Calling a pot=1 and each plate=1 isn't always correct. Every system is different and it can be calculated with proper measurement. I'm guessing Southerhighlander has enough info to state what he manufactures. Pot stills will have different necks, onions, lyne arm direct, etc and thus will have drastically different numbers. Your pot still might have 3-4 theoretically plates. But he's also correct saying you'd have to distill many times to approach what he's making in one pass, and your last charge would be very high proof going in. Depending on your system type, you probably would have to leave a lot of good liquid behind as to not damager your equipment if you fall below a heating element.
Thanks a lot each one of you.
Much clearer now....
Does this further imply that each plate in the rectifying column is at a marginally higher temperature than the one below it and can the temperature of each plate be controlled externally or manually?
and WHY wash with water if the distillate has to rectified in another set of 2 to 3 columns (like for vodka I assume)?
Each plate is at a slightly *lower* temperature than the tray below it. In a typical vodka column the base would be at >100°C (212°F) and the top at around 80°C (176°F) - but these will vary with time in a batch column.
The way to understand the temperatures is that boiling causes the more volatile component (ethanol) to move to the top of the column while the less volatile component (water) concentrates at the base of the column. The top product containing more ethanol than the base product will have a lower boiling point than the base product. And each plate will contain a slightly higher concentration of ethanol than the tray below it and therefore be at a slightly lower temperature than that tray.
When we control the heat input or reflux on a column it seems as though we are controlling the temperature, but in fact we are controlling the composition and the change in temperature is a *result* of the change in composition. It may seem that the change in temperature is causing the change in composition but it is really the other way around.
You cannot control the temperature of each tray individually. As you change the heat input or reflux the entire temperature profile in the column will change. We use temperature as the parameter to measure because it is the fastest and cheapest measurement to make to indicate the composition, which is what we really want to control. Another important factor in large vodka columns is that any change in composition profile across all the plates will result in different temperature changes on different plates. This means that the temperature swing will be much higher on some plates than on others, so we can use these sensitive plates to measure the temperature and get the quickest indication of a change in composition profile. So you get the seemingly strange situation where the reflux to the top plate is controlled by the temperature 2/3 of the way down the column.
The reason for washing with water is complex. Basically, the *relative* volatility of different alcohols changes according to the amount of water present. By increasing the amount of water you can cause a higher alcohol (eg amyl alcohol or fusel oil) which would normally be less volatile than ethanol and therefore concentrate near the base of the column to increase in relative volatility and therefore migrate to the top of the column in higher quantities. The calculations are horrendous and even the most powerful computer simulations struggle with the hydroselection column. When I have had to design these columns I simply took the number of trays and water feed ratio from plants that worked well, and limited my design to getting the plate hydraulics optimized for capacity and pressure drop.
I forgot to mention earlier... If you have a packed column e.g. just a column filled with glass beads or other packing material, your theoretically number of plates would be very high. If you could pack whatever is coming off the top of your pot you could have a lot of "plates" in there, theoretically. If you ran a recycle stream from your effluent back to one of your "plates" you'd change the composition of that area, and you'll get an even higher proof of of your system. There are a lot of ways to increase your separation with modification, which would put you into a hybrid system at that point.
Meerkat is spot on with each plate being cooler as you progress upwards in your column, due to the change in composition. It's a weird concept for a lot of people to grasp when we always hear "hot air rises". It's really just "less dense rises", and with air you don't have a compositional change like you do during distillation.
Here is a really good video that might teach you a lot about the distillation process talked about here. This is a video made for Shell about crude oil distillation but the process is very similar for many parts of the process. This gives a really good overview of distillation and how plates are used.
Reply:On 3/9/2020 at 7:46 PM, Southernhighlander said:
Reply:2 hours ago, needmorstuff said:
Reply:58 minutes ago, kkbodine said:
Here's another similar. https://www.drippingspringsvodka.com/our-vodka/
"Dripping Springs is micro-distilled 20 times in copper pot stills in small 50-gallon batches. It is then mixed with pure, mineral-rich artesian spring water from the Texas Hill Country before a final clarifying slow filtration through Swedish activated charcoal. Dripping Springs is lush and balanced, with a smooth finish."
When you view the distillery on Google with a sat view you don't see grain silos. It's usually a pretty safe assumption that without grain silos you won't be distilling from scratch but starting with GNS.
Starting with a mash, I wonder how long it would take to do 20 actual distillations in a 50 gallon pot still filled what 40 gallon with a charge?
Funny stuff :)
Reply:14 hours ago, Roger said:
You notice how the condenser feeds directly into the 55 gallon barrels? It looks like every single still is setup the same way.
How do you suppose they make cuts?
Maybe that's why they need that Swedish activated charcoal. LOL
Their web page also says besides vodka they make gin in 40 gallon batches. Again if using these same stills, how do they make any type of cuts?
What a waste of equipment that could be making some good whiskey or something it's designed to make a whole lot better/easier!
You dont make cuts when making vodka from GNS. The "pot still" charade is just a way to move the spirit from a category to a class. It can also be done with filtration, or the wave of a pen on a processing report. It's just marketing.
Personally, I'd still make cuts if pot stilling GNS after diluting with water as you'll be able to remove more and clean up the spirit a tad bit more. Cuts would be very small for vodka. Gin on the other hand will need normal gin style cuts due to the botanicals.
But unless there is more than meets the eye in that photo I don't see a way to make any cuts.
As already said, pure marketing at a huge waste of energy!