Animated pot still
Heat, boiling, vapor travel, condenser flow and receiver drip respond to actual collection rate.
Receiver cuts
Cut timing uses recovered ethanol progress, spirit style, vapour ABV and temperature.
Live distillation curves
Hover any chart for exact values. Click to expand full run history. VLE diagram shows live operating point on the equilibrium curve.
How to use this simulator
The simulator runs a full pot still batch distillation from ambient temperature to the end of the run. Every parameter affects the physics.
- Set your wash. Enter boiler volume and wash ABV. A typical sugar wash is 8–12%, a grain wash 6–9%, and a fruit wash 8–14%.
- Choose a spirit style. Each preset adjusts cut thresholds — vodka uses the tightest hearts window, brandy the widest. Pot efficiency and cut timing adjust automatically.
- Set heat input. A 2–3 kW element is typical for home use. Higher heat produces more vapour per hour but can reduce separation quality.
- Set methanol ppm. Sugar washes are typically 50–300 ppm; fruit washes can be 500–3,000 ppm. The methanol chart shows why foreshots must always be discarded.
- Click Start. Use the speed slider (1–50×) to run at pace. The animated still, all six charts, and the fraction jars update in real time.
- Export or review. When the run ends a summary card shows yield, estimated bottles and methanol discarded. Export CSV to analyse the full run data.
Detailed calculation model
This simulator uses a dynamic batch pot-still model grounded in real thermodynamics: ethanol concentration falls, vapour strength declines, head temperature rises from ambient to bubble point, production rate responds to heat input, and the run progresses from heads into hearts and tails.
1. Boiler inventory
The boiler tracks ethanol, water and methanol volumes separately. As product is collected, each component is removed according to its instantaneous vapour composition, conserving total moles at each timestep.
2. Van Laar VLE
Activity coefficients use the Van Laar model (A₁₂ = 1.6798, A₂₁ = 0.9227), more accurate than 2-suffix Margules near the azeotrope. Bubble-point temperature is solved numerically via bisection at each step, giving a realistic temperature curve throughout the run.
3. Thermal-mass heat-up
Temperature rises as dT/dt = Q·η / (m·Cp), where m is boiler mass, Cp is the mixture heat capacity, and η = 0.80 accounts for vessel losses. A 25 L boiler at 2.4 kW takes roughly 55–60 minutes to reach bubble point, which matches real distillery experience.
4. Energy-balance vapour rate
Vapour rate is derived from Q_vap = Q_in × ε_still, divided by the mixture latent heat ΔHvap (ethanol 841 kJ/kg, water 2260 kJ/kg, weighted by distillate composition). Rate naturally decreases as ethanol depletes and more energy goes into vaporising water.
5. Methanol (3rd component)
Methanol is tracked as a dilute 3rd component using its own Antoine equation and a fixed activity coefficient (γ = 2.2). Being more volatile than ethanol, it concentrates strongly in foreshots — exactly why the first 50 mL per 20 L is always discarded in responsible distillation.
6. Cut classification
Cuts use spirit-specific profiles based on the DistilCalc cuts calculator. The primary driver is recovered ethanol progress, with vapour ABV and temperature used as guardrails to prevent misclassification during heat-up and late-run decay.
The simulator solves the temperature at which total pressure reaches 760 mmHg, then calculates ethanol vapour mole fraction from modified Raoult's law and converts that back to a condensed liquid ABV. This captures the full distillation curve — from the steep early rise to the gradual tailing-off as the hearts window closes.
- Whisky: balanced pot-still profile, keeping moderate congeners for grain character.
- Rum: slightly wider hearts, allowing more late character for heavier styles.
- Brandy: wider and lower cuts — fruit spirits retain more character deeper into the run.
- Gin: clean, tight profile to avoid solventy or heavy notes masking botanicals.
- Vodka: narrowest hearts window, prioritising neutrality and a clean spirit.
The speed slider goes to 50×. Internally the simulator divides each animation frame into small calculation steps, so high-speed settings are less likely to skip past the hearts window.
Whisky Tasting Journal: Pair your simulated runs with real batch records. 100 structured entries, score /100, buy-again rating. 6 x 9 in, 116 pages, cream paper.