Pot still simulator
Alcohol balance (charge, heads, hearts, waste) and heating power for a single-run pot still with no rectification. Ethanol-water equilibrium is modelled properly, so the 95.6% ABV azeotrope and the falling distillate strength both emerge from the physics.
Charge
Volume is the liquid charge after botanicals displacement.
Cuts
Dumped at the strength the model says the first distillate leaves at.
Power & cost
Loss % covers still-body radiation and anything else between the meter and the liquid. Leave 0 for the ideal figure; calibrate it from a logged run below.
Calibrate loss from a logged run
Model settings
1 stage = plain pot still. More stages approximate a plated column at high reflux - only for experimenting.
Alcohol balance
Distillate strength through the run
Instantaneous ABV %
Cumulative ABV %
Pot & vapour temperature
Pot °C
Vapour (column top) °C
Energy & cost
How it works / assumptions
- Vapour-liquid equilibrium: Van Laar activity model + Antoine vapour pressures at 1 atm. Azeotrope emerges at ~89.4 mol% (95.6% ABV) - pure physics, no lookup curves.
- With 1 theoretical stage the column-top temperature equals the pot temperature - saturated vapour condenses at the same temperature it left the boiling liquid, which is why the two gauges on a pot still track within a degree of each other. The lines separate only if you add stages (a refluxing column).
- The pot is simulated in ~1,500 small evaporation steps (Rayleigh distillation): each step removes equilibrium vapour, so pot ABV falls, boiling point climbs, and distillate weakens exactly as you see on the still.
- Energy = sensible heat to bring the charge to the boil + latent heat of everything vaporised + sensible heat as the pot climbs from first-boil to switch-off temperature. Divide by (1 - loss%) for electricity at the meter. The chiller is NOT included - it is a separate load.
- Densities are 20°C ethanol-water values; ABV is by volume, ethanol 0.789 kg/L. LPA = litres of pure alcohol.
- Heads are assumed dumped at first-vapour strength.
- Cross-checking a real run: set "still switched off when" to total collected litres and compare the model's end pot temperature with your gauge. If they disagree by several degrees, suspect the pot thermometer placement or the charge hydrometer reading.