This iStill Blog post is about column size. Column diameter to be more precise! We’ll dive into how and why it is important. And how the iStill Team translated Odin’s Theory on Distillation to new, innovative designs.
Odin on Distillation Theory
“A taller column is good for purity, and a wider one for more performance.” That’s distillers lore of old. What does Odin think about that? Does he agree? Yes and no, but mostly no.
A taller packed column can hold more reflux and more reflux leads to more distillation cycles and more distillation cycles leads to more purity: higher ABV and less taste transfer. But only if you apply reflux! Without reflux, a taller packed column just acts as a potstill column. No difference in purity in potstill mode.
A wider column can produce more spirits, but only if we beef up the power input. At the same power input, a wider column will produce just as much as a smaller diameter column, with the only difference that the vapor speeds in the wider column will be lower. Lower vapor speed for less smearing. So in potstill mode, without (much) reflux, it is actually giving slightly better separation than a smaller column. Slightly more purity that is. Wow, so wider columns for more purity? Yes, indeed, if you run them as potstills!
One more. A taller column can hold a higher liquid bath, generating more distillation cycles. If you use reflux, in pure mode, that is. A taller column, in pure mode, therefore has a bigger >95% alcohol bath near the top. This generates a more stable run with higher outputs. So, contrary to established “knowledge” a wider column can be good for purity. And a taller column gives more product.
A wrap-up, Odin, please?
In reflux mode, when a pure vodka or GNS is your goal, a taller column will give you more output per hour than a shorter column.
In potstill mode, when taste rich drinks like rum or brandy or whiskey are your goal, a wider column can either create less smearing or generate more product. More product, because if you dial up the power input and generate the same vapor speeds (for the same taste profile) as in a narrow column design, you will actually be able to make more product per hour.
The old generation iStills
The older generation iStill 500 has a 4 inch diameter column. That’s 10 centimeters. The surface area can be calculated by Pi*R*R = 3,14*5*5 = 78.5 centimeters square. Due to the column diameter, the non-optimized collection system and the column cooler design, it was pretty much limited to a maximum power input in pure mode of around 9 kW.
The NextGen Column Innovation
The iStill 500 NextGen uses a 5 inch diameter column. The surface area of the 500 NextGen column is therefore 3,14*6.25*6.25 = 122.7 centimeters square.
If we divide 122.7 by 78.5, we can calculate that the new 5 inch column has a surface area that is no less than 56% larger! If we multiply 9 kW (the power setting on the old generation iStills) by 1.56, we can now calculate how much power the new column can handle. We leave the now optimized collection system and column cooler out of the equation for now. Here we go: 1.56*9 = 14. The new column can easily handle 14 kW.
Real life consequences?
As a result of the wider diameter NextGen column your iStill 500 NextGen produces 56% more vodka or GNS. That’s 16 liters of 190 proof per hour instead of just 10.5 to 11 liters.
But the advantage does not just apply to vodka and pure products. In potstill mode, when you make taste rich products like rum, whiskey or brandy, the wider column also gives you 56% higher production rates, when we beef-up the power input to match the vapor speeds (and the same resulting smearing of late Heads and early Tails into Hearts) of the old column.
A finishing run on a taste rich product can now be done at 9 kW instead of just 6 kW, resulting (again) in 56% higher production rates … and much shorter run times!
Vodka and GNS production doesn’t stop at 14 kW. Remember that the older units weren’t optimized for collection and column cooling? Well, we also solved those issues. The result? iStills NextGen columns can now make vodka and GNS at full throttle. That’s 18 kW for the iStill 500 NextGen and 36 to 40 kW for the iStills 2000 and 5000 NextGen. Another gain of like 40%. How we did that? Please keep following the iStill Blog. We’ll post about it in just a few days …
Bigger is better …