Calculation of a Pot Still Distillation Run

Heres a rough stab I've had at this....

One assumption is that all the heat input is used to vaporise the vapour, eg no heat losses, but this should be a minor error. (I'll just claim that all pot stills are extremely well insulated ...

If you don't know what your power input is (say you are using gas heating instead), adjust the value used until the "time to heat up" is close to what you expect.

This can also be used for double & triple distillations, eg
  • 20L of 15% will give around 6L of 45% (use say a 25% cut-off)
  • feed this back in & see that you'll get around 4L of 68%, then
  • distilling this gives about 3.4L of 80%
It's not quite such an accurate calculation at the higher %alcohols, because the timesteps are too large. An indication that that calculation has got where it's going is when the sample purity first goes -ve.

Input your Pot still characteristics

Initial Volume of Wash L
Alcohol Content % by volume
Initial Temperature C
Power during Heat-up W
Power during Distillation W
%Internal Reflux %
Time-step for calculation min

Change any of these values & see the difference in the table below ...



Results

Time to Heat up Still contents

TimeTempCollectedPurityTotal CollectedTotal Purity


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