Now, as the run progesses, more and more alcohol is taken from the initial boiler charge. In other words: the boiler contents get ever lower in alcohol. This will influence the gases in the column. The lower the alcohol percentage in the boiler, the lower the gases will be in alcohol as well. Lower proof gases translate to higher temperature in the column.
As you can see in the above chart, higher temperature gases relate to lower proof output. We don't want that. So, during the run, you slowly need to adjust the needle-valve. Close her down bit by bit, as to create more reflux. Remember that more reflux activates more of the micro-distilleries in the column? Please do. If you don't remember, please read the previous post as it is quite important that you wrap your head around that!
Closing the needle-valve more and more, during the run, will keep the alcohol percentage at around 60 to 65%. Aim for 90 degrees C and you will be fine.
Other advantages? I mean other than this being easy? Yes! Later on during the run Tails can come over. Tails stand for the last bit of the run, that's contaminated with higher boiling point alcohols that cause stomach aches. We don't want them in the drink either. And here comes the really good part: towards the end of the run, when you create more reflux by slowly closing the needle-valve ... you also create more redistillations in the column that act as a buffer for Tails.
By upping the reflux amount, you get better Tails control!
Tails - the end of the run
When to stop the run? Prior to when excessive Tails come over. But at what temperature is that? That's really depending on what product you make, how long you want to age it, and how well mashing and fermenting went. As a general rule of thumb: stop distilling when the temperature at the lowest probe reaches 96.5 to 97 degrees C. That's not the temperature at take-off, higher up in the column, but low in the column.
Alternative procedure: distill 1.5
Here's an alternative approach. Do a stripping run on around 50 liters of distillers beer by leaving the needle-valve wide open all run, while keeping the power input set at 4 kw. Until the temperature at the bottom is 99 degrees C. Like this, you will strip 50 liters of 8% beer into 10 liters at 40%.
Now clean out the boiler and column ... and add the 10 liters of 40% low wines back into the boiler. Top up with 40 liters of fresh wash. You now have pretty much twice the amount of alcohol in the boiler.
Proceed as in the first example: stabilize, take Heads, then collect Hearts at 90 C, et cetera.
The advantage? Because you now get to play with twice the amount of alcohol, transition points between Heads, Hearts and Tails take a bit longer. Easier for the beginner to learn how to distinguish them ...
See the knob? That's what you control reflux with ...
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