Industrial i-butane/n-butane splitter — a PENG-ROBINSON process flowsheet
A close-boiling isobutane/n-butane splitter as reported by Klemola and Ilme (Ind. Eng. Chem. Res. 1996, 35, 4579) — the relative volatility between the two isomers is small (~1.3), so the column needs many stages and a high reflux ratio for a sharp split, unlike the wider-boiling LPG splits elsewhere in this library.
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- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: COL.
- Focus areas: Isomer separation, Distillation, Textbook.
- Thermodynamics
- PENG-ROBINSON
- Components
- isobutane, n_butane
- 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("isobutane-nbutane-splitter")
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
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.
Perry Ch.13 Example 4: sloppy-butane three-cut splitter
A three-cut column with a side draw producing a deliberately 'sloppy' (off-spec, cheaper-to-make) butane cut between a propane overhead and a pentane-plus bottoms, from Chapter 13 of Perry's Chemical Engineers' Handbook.
Aromatics column (Strigle)
A simple aromatics splitter recovering benzene overhead from a toluene/xylene-heavy feed, as described by R. Strigle (Gulf Publishing, 1987) — a classic packed-column textbook design case.
Depropanizer (Strigle)
A depropanizer recovering propylene and propane overhead from a C₄-and-heavier hydrocarbon feed, as described by R. Strigle (Gulf Publishing, 1987).
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).