Light-ends fractionation train — a PENG-ROBINSON process flowsheet
A classic three-column light-ends train splitting an ethane/propane/ n-butane/n-pentane feed into four near-pure products: DEC2 (deethanizer, 5 bar) rejects ethane overhead, DEC3 (depropanizer, 5 bar) takes the propane cut, and DEC4 (debutanizer, 2 bar) splits n-butane from n-pentane. A genuinely wide-boiling train — DEC2 and DEC4 both land in the documented successive-substitution residual plateau (converge to a physically correct, sharp separation just above the strict 1e-5 tolerance) rather than a clean converged status, the same class of behavior already accepted for the DME casebook entry. From the ChemSep casebook (light-ends fractionation).
166 views 0 forks
- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: 3× DEC4.
- Focus areas: Distillation train, NGL fractionation, Wide-boiling column, Light ends.
- Thermodynamics
- PENG-ROBINSON
- Components
- ethane, propane, n_butane, n_pentane
- Unit operations
- 3× DEC4
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("light-ends-train")
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
Natural gas fractionation train
A four-column NGL fractionation train — demethanizer, deethanizer, depropanizer, debutanizer — recovering pipeline-spec sales gas plus ethane, propane, and butane products from wellhead-pressure raw natural gas, after Luyben (Ind. Eng. Chem. Res. 2013, 52, 10741).
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.
BTX aromatics train
Benzene / toluene / p-xylene split in a two-column train — 99+% purity on all three products. From the ChemSep casebook (CScasebook_BTX).
DME synthesis (methanol dehydration)
Catalytic methanol dehydration (2 CH₃OH → (CH₃)2O + H₂O, 82% conversion) followed by two atmospheric-pressure columns: DMECOL rejects dimethyl ether overhead (~88% pure — the ternary's relative volatility at this pressure caps a single column's overhead purity there) via the inside-out method (a genuinely wide-boiling ternary — DME boils at -24 C, water at 100 C), then MEOHCOL recovers unconverted methanol (99.9% pure) from the water byproduct (99.3% pure). From the ChemSep casebook (DME_ie101583j).
Depropanizer (NGL fractionation)
The raw NGL recovered by a cold separator is fractionated: a depropanizer column splits it into a C₃-and-lighter overhead (propane + a little ethane, the LPG product) and a C4+ bottoms (butanes + natural gasoline). The column is solved with the component-flow Naphtali-Sandholm MESH (method "ns"), which carries every component flow as an unknown so the feed-vs-products material balance is an equation the solver closes by construction — the right tool for a sharp C₃/C₄ cut, where a reduced-form column would drag the split off and leak a few percent of a component. Peng-Robinson handles the light-hydrocarbon VLE; the built-in sensitivity sweeps the reflux ratio against the reboiler duty (the classic distillation energy trade-off).
NGL fractionation train (depropanizer + debutanizer)
The full two-column NGL fractionation train of a gas plant: a raw NGL is split into three products. The depropanizer takes a propane-and-lighter overhead (the propane product), and its C4+ bottoms feed a debutanizer that splits butane overhead from a natural-gasoline (C5+) bottoms. Both columns use the component-flow Naphtali-Sandholm MESH (method "ns") so each sharp cut conserves every component exactly; the two columns solve in sequence (no recycle) and the whole train closes on mass. Peng-Robinson handles light-hydrocarbon VLE; the debutanizer runs at a lower pressure (7 bar vs 18) so its reboiler stays within a reasonable temperature.