Flash separation — a NRTL process flowsheet
An isothermal flash drum at 358 K splitting an ethanol–water feed into ethanol-rich vapor and water-rich liquid products.
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- Rigorous NRTL thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: DRUM.
- Focus areas: Flash, VLE, Vapor–liquid split.
- Verified fast convergence — a real, measured solve time, not an estimate.
- Thermodynamics
- NRTL
- Components
- ethanol, water
- Unit operations
- DRUM
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("flash-separation")
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 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.
Polymerization reactor comparison: CSTR cascade vs. tubular (PFR)
The same monomer feed, split 50/50 into two trains at equal total reactor volume: a 3-stage CSTR cascade (each stage blending its own new polymer with the MWD already carried by the stream from the stage before it) versus a single tubular (PFR) reactor. Both converge to a real, different Mn/Mw/PDI — the PFR reaches higher conversion at the same total volume, but its cumulative polydispersity is measurably broader than the cascade's, because chain length drifts continuously with conversion along the tube while each CSTR stage makes its own local production under one fixed monomer concentration. See the 'Polymerization Reactors' docs page for the full reasoning.
Helium liquefaction (Linde-Hampson cycle)
A Joule-Thomson liquefaction loop: helium is compressed, aftercooled, precooled well below its ~40-51 K JT-inversion temperature, then throttled through a valve into a flash drum that draws off liquid helium while the cold vapor recycles back to the compressor suction — the same JT-cycle physics as the platform's LNG/refrigeration loops, run on a fluid whose inversion curve makes precooling mandatory before the throttle can cool it at all.
Cement kiln calcination + CO2 liquefaction
Preheated limestone (CaCO₃) enters an indirectly-heated rotary kiln that calcines it toward CaO, releasing a CO₂-rich off-gas; the gas passes a knockout drum, then is compressed and cooled to liquefy the CO₂ for transport/storage.
NGL fractionation: single-shell Petlyuk dividing-wall column
A natural-gas-liquids cut (ethane / propane / n-butane) split into three on-spec products by ONE thermally-coupled dividing-wall column instead of two columns in series. This uses the native Petlyuk unit op: a prefractionator whose reflux and boilup are supplied by the main column (the single condenser + single reboiler), solved by an outer Wegstein loop that converges the bidirectional vapor/liquid coupling to self-consistency — the coupling legacy sequential-modular solvers approximate with two connected columns whose recycle fails to converge.
Ethanol–water distillation
An 8-stage column concentrating ethanol overhead toward the azeotrope (the headline demo).