Raspberry Pi Temp Controller

[eStill]

trickled down a slanted metal washboard

That's exactly what I had in mind when I thought of a weir.

I only had a gin extract run to do tonight (1L 80% ABV soaked in top secret specialist herbs, diluted down with 2L distilled water, run through my pot head) , but I can see that about 5700 seconds into the run, the controller decided to ramp up the input power (yellow line) as the coolant (grey line) was coping. At about the same time, I realised I had only half-filled the reservoir, which is why the coolant temp drops off as I fill it. then the coolant starts to rise back up to about 25 degrees and the controller back off the power input again as the vapour temp (blue line) start to hit 97 degrees. this definitely allows the coolant to cool from 7500 seconds onwards.

I'm calling that a result.

[Mikey-moo]

Sounds great! I love your little weir!

Loving the secret blend of botanicals too. I've been meaning to have a go at Odin's gin recipe but I just can't find the time.

[eStill]

Just for your curiosity (and discussion), here is a typical first pass vapour temperature / time curve, starting with a wash at 14%. (Orange line is vapour just above the wash, blue is vapour at the top of the fractionating column.)

This produces a vodka, which I cut at a point where the ABV is 80%, then dilute to 40% with tapwater. The following is the second pass vapour temperature / time curve using using that dilute vodka as a wash.

Really, there was no need for the second pass: it was just for curiosity, but I read this as an indication of improvement of the neutral spirit.

[Mikey-moo]

Do you macerated the botanicals or do you use a gin basket?

[eStill]

Do you macerated the botanicals or do you use a gin basket?

Still (!) experimenting at the moment. I've been soaking the plants in 80% neutral, then I add that to the pot with an equal amount of tapwater. (I think that's what we mean my "macerating".) I then suspend the plants in a basket within the pot. (Almost the same as a gin basket, which normally goes in the high temperature vapour rather than the low temp.) I'm not convinced that last step makes any difference.

Then I run with a pot still head until the overall ABV is about 75%. A lot of the flavour seems to come over quite late in the process, with the higher temperatures. I continue the run after that point, but the rest (from appx 75% ABV down to 20%) goes into tails which I add to my next 15% wash.

[Stew8]

This is the output from the first attempt - I'm really pleased.

The glitch in temps as it was rising was becuase I needed to add something and turned it off and lifted the lid.

Sensor 1 is at the top of the column
Sensor 2 is the bottom just above the boiler
Sensor 3 is ambient
The yellow line alcohol % that normally decreases over time (manual entry)
ml/min is the average volume collected - this is the next challenge... I'm going to look at rain gauges.


I’m going to take more readings when I do the next run!

[eStill]

I'm going now o do an experiment running my coolant back into the reservoir over a weir from a height in the hopes it'll cool a good bit.

It didn't. It cooled it an immeasurably small amount.

[eStill]

ml/min is the average volume collected - this is the next challenge... I'm going to look at rain gauges.

For small qty, that's the only way. I use a flowmeter to make sure my coolant is running but it wouldn't measure flows sufficiently low for the output.