Beer column: 8% ethanol to 53% (Wilson) — a WILSON process flowsheet
The first column of a distillery on the Wilson equation — the oldest local-composition model, fine for a fully miscible pair like ethanol-water and unable by construction to represent a liquid-liquid split, which is why it is offered for this pair and not as a default. An 8 mol% fermenter beer, 12 stages with the feed near the top (stage 3) as a beer column is run, reflux 1, 15% distillate: 53 mol% ethanol overhead and a stillage bottoms with no ethanol left, 1.37 MW on the reboiler for 100 mol/s of beer. Ethanol-water is the one binary the package carries regressed Wilson parameters for; everything else falls back to UNIFAC.
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- Rigorous WILSON thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: COL.
- Focus areas: Distillation, Wilson, Ethanol, Beer column, Activity model.
- Thermodynamics
- WILSON
- Components
- ethanol, water
- Unit operations
- COL
Opens in a new tab, loaded straight into the app — no setup.
Read the step-by-step guideReproduce this exact result from Python — the real client.get_example() → run_and_wait() path, not a mockup.
from flowsim.sdk import FlowSimClient
client = FlowSimClient()
example = client.get_example("ethanol-beer-column-wilson")
sim = client.create_simulation(example["title"], example["flowsheet"])
result = client.run_and_wait(sim["id"])
print(result["status"]) # "converged"
streams = client.streams(sim["id"])Related models
Ethanol-water rectifier (UNIQUAC)
The ethanol-water rectifier on UNIQUAC — Abrams and Prausnitz's local-composition model with its surface and volume parameters, here on the one binary the package carries regressed parameters for (every other pair falls back to UNIFAC, which the package description says). 30 mol% feed, 20 stages, reflux 2.5, 40% distillate: 75 mol% ethanol overhead and ethanol-free water in the bottoms at 5.7 MW. The cut is kept at 0.40 on purpose: at 0.32 the spec asked for a 94% distillate past the 89.4% azeotrope and the column reported exactly that, and at 0.36 it pinched a hair short of it (balance 5e-3). Compare with the same column on NRTL and Wilson to see how much three regressed models agree on one well-measured pair — a few tenths of a percent in the distillate.
Ethanol-water heat-and-flash (Van Laar)
The simplest separation there is, on the simplest activity model that still gets a non-ideal pair right: a 40 mol% ethanol-water stream heated to 356 K at 1 atm and flashed adiabatically, on the two-constant Van Laar equation — the oldest of the family, temperature-independent, cheap to fit from a single azeotrope point. What it computes: 55% of the feed vaporizes at 356 K, the vapour at 54 mol% ethanol against 22% left in the liquid, on 2.75 MW of preheat. Ethanol-water is the one pair the package carries regressed constants for; other pairs fall back to UNIFAC.
Ethanol–water distillation
An 8-stage column concentrating ethanol overhead toward the azeotrope (the headline demo).
Tray efficiency — real trays vs ideal stages
The same ethanol–water column solved with a Murphree vapor tray efficiency of 0.7 instead of ideal equilibrium stages. A real sieve/valve tray never reaches full vapor-liquid equilibrium — the vapor leaving it only partly approaches the equilibrium composition with the tray liquid, mixing in un-equilibrated vapor from the tray below: y = E·K·x + (1−E)·y_below (Murphree 1925). At E = 0.7 each of these 12 trays does 70% of an ideal stage's work, so the overhead ethanol is lower than an equilibrium column of the same tray count would predict — which is exactly why a real column needs more trays than a shortcut (ideal-stage) calculation says. Both HYSYS and Aspen RadFrac expose this per-tray efficiency; set murphree_efficiency back to 1.0 to recover the ideal-stage column. The efficiency auto-selects the component-flow Naphtali-Sandholm solver (the reduced-form solvers carry no explicit per-tray VLE row to apply an efficiency to).
Distillation column startup dynamics (feed-rate step)
An 8-stage ethanol-water column at a reduced startup feed rate. Solves the steady state normally; switch to the Dynamic solve mode with weir/level-controlled hydraulics enabled and step the feed rate up (e.g. 6 → 9 mol/s) to watch the bottoms draw genuinely rebalance to the new throughput as the tray inventories fill — a feed-rate disturbance no fixed-hydraulics dynamic model (incl. this same column's own default rigorous mode) can show at all. Honest bound: the vapor traffic is held at its steady-state value in this mode, so the distillate draw (condenser-level-controlled off vapor inflow) does not move for a feed-rate-only step — only the liquid/bottoms side responds.
Perry Ch.13 Example 3: butane/pentane splitter
A simple two-cut distillation splitting butane overhead from pentane bottoms, from Chapter 13 of Perry's Chemical Engineers' Handbook.