Methane / n-decane high-pressure separator (SAFT-VR Mie) — a SAFT-VR-MIE process flowsheet
A 60/40 methane / n-decane well fluid at 60 bar and 320 K through one high-pressure separator, on SAFT-VR Mie (Lafitte et al. 2013): the full Mie-segment perturbation theory — a1/a2/a3 monomer terms plus the TPT1 chain — with cited pure-component parameters and no binary correction. What it computes: 49 mol/s of gas at 99.9% methane and 51 mol/s of oil holding 22 mol% dissolved methane, the K-values 3.9 for methane and 0.001 for decane. Two components and one flash on purpose: this package costs 7.5 s per flash here and 40 s per flash with four components, so a separator train on it does not belong on a gallery card (one was killed after 15 minutes). Non-associating fluids only — no water, no alcohols — which is the package's own stated scope.
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- Rigorous SAFT-VR-MIE thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: HP SEP.
- Focus areas: SAFT-VR Mie, Separator, High pressure, Gas solubility, Molecular EoS.
- Thermodynamics
- SAFT-VR-MIE
- Components
- methane, n_decane
- Unit operations
- HP SEP
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("methane-decane-hp-separator-saft-vr-mie")
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
Pressure-swing ethanol dehydration (Gᴱ mixing rule)
Ethanol–water is the classic azeotrope, and pressure-swing distillation breaks it without an entrainer: the azeotrope moves with pressure, so a low-pressure column and a high-pressure column pass each other's azeotropic distillate and each recovers a pure product. The whole process only works if the property package tracks that shift — which is exactly where a conventional package choice falls between two chairs. This flowsheet runs the high-pressure column at 15 bar on pr-mhv1: Peng-Robinson with an MHV1 excess-Gibbs mixing rule, so the cubic equation of state gets its attraction parameter from NRTL's excess Gibbs energy instead of from a single binary interaction constant. Switch the thermo package (Solver menu) and compare the predicted azeotrope: | package | 1 atm | 15 bar | valid at 15 bar? | |---|---|---|---| | NRTL | 0.891 | 0.802 | no — γ-φ is a low-pressure formulation (~10 bar) | | Peng-Robinson (kij) | 0.586 | 0.613 | yes, but a kij cannot represent this azeotrope | | pr-mhv1 | 0.949 | 0.798 | yes | (mole fraction ethanol; the repo's DECHEMA-validated 1 atm anchor is 0.894.) At 15 bar pr-mhv1 lands within 0.005 of NRTL while remaining a genuine equation of state, whereas plain Peng-Robinson is off by ~0.19 and puts the azeotrope in the wrong place entirely. Selecting nrtl here also trips the applicability guard, which warns that the activity model is past its pressure ceiling and names the fix. The flowsheet demonstrates the mechanism on itself. Drop the column pressure to 1 atm and re-run, changing nothing else: the solve fails with SPEC_THERMODYNAMICALLY_IMPOSSIBLE, because at atmospheric pressure the requested bottoms purity sits beyond the azeotrope and no column can reach it. At 15 bar the same specification converges and the bottoms leaves at x_EtOH ≈ 0.924 — past the atmospheric azeotrope of 0.894, which is precisely the composition an atmospheric column cannot cross.
CO2 dissolution in n-decane at 60 bar (PC-SAFT)
A CO₂/methane gas contacted with n-decane at 60 bar and 313 K — the screening question behind CO₂-EOR injection and physical-solvent CO₂ removal: how much of the gas the oil takes up, and how much heat that releases. It runs on PC-SAFT (Gross & Sadowski 2001, chain + dispersion), the molecular equation of state for exactly this combination of a supercritical light gas and a long-chain alkane. The adiabatic mixer warms from 313 to 328 K on the heat of dissolution, and the isothermal contactor at 313 K leaves 186 mol/s of loaded oil (25.5 mol% CO₂, 20.6% methane) against 14 mol/s of lean gas at 82% methane: 95% of the CO₂ and 77% of the methane dissolve. Building this card exposed a flowsheet defect worth knowing about: the (P,H) flash behind every adiabatic mixer verified its answer by re-solving over the whole 80-1200 K range, and a SAFT density root at 80 K returns a residual enthalpy of the wrong sign, so the mixer reported 80 K for a state that is 328 K. The verification now brackets outward from the branch solution and keeps it when no sign change exists. Still bounded: PC-SAFT's bubble-point routine puts this mixture's bubble point at 421 K while its own flash finds vapour at 300 K — the flash is right and is what the results use; the saturation routine is the documented follow-up. No binary kij beyond what the package ships.
Ethanol-water column at 6 atm (SRK + MHV1)
The ethanol-water column everyone knows, run at 6 atm on the Gᴱ-mixing-rule package: Soave-Redlich-Kwong whose mixture energy parameter comes from NRTL's excess Gibbs energy through the MHV1 rule (Michelsen 1990) instead of a kij — the package built for polar, hydrogen-bonding mixtures at pressure, where a γ-φ activity model is past its ~10 bar ceiling and a plain cubic with van der Waals mixing has no hydrogen bonding at all. A 10 mol% ethanol feed through 16 stages at a reflux ratio of 2.5 gives a 66.7 mol% distillate and an ethanol-free bottoms, 2.6 MW on the reboiler. Read it against NRTL, which at 6 atm is still inside its own range: the two packages put the pressure-shifted azeotrope in different places — 0.88 mol fraction ethanol here, 0.84 on NRTL at 6 atm (0.97 against 0.89 at 1 atm) — so this card shows where the MHV1 rule sits, not a number to prefer over the fitted binary at low pressure. The cut is kept well short of the azeotrope on purpose: at a distillate ratio of 0.12 the profile pinched against it and the column reported exactly that. Each solve is about a minute, because every stage K-value is a Gᴱ mixing-rule evaluation.
DEA natural-gas sweetening at 50 bar
A high-pressure gas-treating unit on diethanolamine, the canonical secondary amine: 100 mol/s of 5% CO₂ natural gas at 50 bar and 313 K against 200 mol/s of 25 wt% DEA (5.4 mol%), the rich amine let down to 1.8 bar, heated to 388 K and steam stripped, the overhead condensed. The enrtl-dea package carries DEA's cited protonation anchor (pKa 8.9) with a screening-grade carbamate constant. What it computes: a treated gas that is pure methane, a rich loading of 0.52 mol/mol — right at the carbamate ceiling of a secondary amine — a 5.1 mol/s CO₂ product at 89 mol% (the rest methane co-absorbed at 50 bar and water), 1.2 MW on the rich heater. Same model bounds as the MEA card: Kremser stages with the K at the entering liquid, open loop, regeneration to zero loading.
Methanol-water column at 10 atm (PR + Huron-Vidal)
A methanol-water column at 10 atm on Peng-Robinson with the original Huron-Vidal (1979) infinite-pressure Gᴱ mixing rule, driven by the fitted methanol/water NRTL binary. 30 mol% feed, 16 stages, reflux 2, 30% distillate: 96.2 mol% methanol overhead, 1.6% in the bottoms, 3.4 MW on the reboiler at 452 K. The point is the pressure: at 10 atm a gamma-phi activity model is at the edge of its ~10 bar envelope, and a cubic with a Gᴱ rule carries no such ceiling. Bound, as the package's own description says: Huron-Vidal wants activity parameters regressed at infinite pressure, and these are the low-pressure DECHEMA ones, so treat the split as the rule's reading of that binary rather than a validated high-pressure number (the SRK + NeqSim card is the one with parameters fitted for the rule).
LDPE: high-pressure free-radical ethylene polymerization
Low-density polyethylene is genuinely made by free-radical polymerization of ethylene at very high pressure (~2000 atm here, in the real 1500-3000 atm industrial range) and high temperature — the exact kinetics MaximaLabs's existing polymerization unit op already models (Arrhenius CSTR, method-of-moments Mn/Mw/PDI), previously only ever demonstrated on an arbitrary 'ethanol' stand-in monomer with a fictional molar mass. This uses the real monomer (ethylene, real molar mass 28.05 g/mol) and the real thermo package for it (peng-robinson, not the alcohol/water-tuned NRTL the placeholder examples used).