Associated gas conditioning — a PENG-ROBINSON process flowsheet
Field gas is compressed, chilled below its dew point, and flashed to knock out NGL/condensate — the sales-gas vs. liquids split every midstream gathering plant runs (Peng-Robinson).
170 views 0 forks
- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 3 unit operations modeled: COMP, COOL, DRUM.
- Focus areas: Midstream, Gas processing, NGL recovery.
- Verified fast convergence — a real, measured solve time, not an estimate.
- Thermodynamics
- PENG-ROBINSON
- Components
- methane, ethane, propane, co2
- Unit operations
- COMPCOOLDRUM
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("gas-conditioning")
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
Cold-separator NGL recovery / dew-point control
A rich natural gas is chilled in the gas/gas exchanger + propane-chiller train (lumped here as one cold box) to -33 degC and let into a cold separator. The heavy hydrocarbons (C3+) drop out as a raw NGL liquid, leaving a leaner sales gas that meets its hydrocarbon dew-point spec — so no more liquid forms as the gas cools in the export pipeline. The cold separator is modelled as an adiabatic flash fed by the chiller, so the single knob (the chill temperature) drives both the NGL recovered and the refrigeration duty: colder recovers more NGL but costs more refrigeration (the built-in sensitivity). Peng-Robinson handles the hydrocarbon VLE; the companion gas-conditioning utilities (hydrate risk, water content, Joule-Thomson choke cooling, and compressor sizing for the sales-gas recompression) quantify the rest of the plant around it.
Deep ethane recovery with propane-refrigerated feed chilling
Associated gas is chilled by an external propane refrigeration package before a demethanizer recovers ethane and heavier as NGL bottoms from a methane-rich residue gas overhead — the cryogenic-chilling role Ortloff's CCS/GSP processes play ahead of the turboexpander in a real deep-ethane-recovery plant. The mechanical refrigeration loop itself (compressor/condenser/valve) isn't separately modeled here; the chiller's duty is represented directly as the feed's cooled outlet temperature (the same honest-simplification pattern used for LNG cold-box examples elsewhere in this library).
Gas compressor air-cooled aftercooler (fin-fan)
A natural-gas booster compressor followed by an air-cooled (fin-fan) aftercooler — the standard way to reject compression heat where no cooling water is available. The compressor raises the gas from 8 to 24 atm (hot discharge ~150 °C); the air cooler then rejects that heat to ambient air, cooling the gas back to 49 °C. Unlike a plain cooler, the air_cooler op closes the air side: from the process duty and the 35 °C design ambient it solves the air mass flow (a 15 °C air rise) and reports the fan power from the given fan static pressure. Honest scope: screening air-side model (fixed cp_air, ideal-gas air density, no fin/row geometry rating); an air cooler cannot cool below ambient, so the 49 °C target sits safely above the 35 °C air inlet.
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).
Cryogenic NGL recovery (GERG-2008 EoS)
A natural-gas dew-point-control / NGL knockout run on the GERG-2008 reference equation of state — the multiparameter Helmholtz model the LNG and custody-transfer industries use because cubic EoS (Peng-Robinson/SRK) are off by several percent on cryogenic natural-gas density. Rich pipeline gas is chilled, let down across a Joule-Thomson valve into the two-phase region, and flashed cold to drop out an NGL liquid (propane/butane-rich) from the methane sales gas. The value is accuracy: on this flowsheet GERG predicts an NGL liquid density ~10% different from Peng-Robinson at cryogenic conditions — enough to change vessel and exchanger sizing. Implemented via CoolProp's multiparameter Helmholtz mixture model (GERG-2008 binary reducing/departure functions), a validated implementation — not a hand-transcription of GERG's thousands of coefficients. Scope: natural-gas / light-hydrocarbon components only (every species must be a CoolProp fluid); see.
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).