How to simulate three-stage condensate stabilization (soave-redlich-kwong)
Wellhead fluid at 60 bar and 320 K — 60% methane with ethane through n-hexane — through a high-pressure separator, a letdown to 15 bar and an adiabatic medium-pressure separator, then to 2 bar and a low-pressure separator, on plain SRK with its shipped kij: the workhorse cubic for hydrocarbons, exactly where it is meant to be used. What it computes: 69 mol/s of HP gas at 76% methane, 10 mol/s of MP flash gas, 5 mol/s of LP gas rich in propane and butane, and 15.9 mol/s of stabilized condensate carrying 0.2% methane and 2.2% ethane — the light ends that would otherwise vent from a tank. The Joule-Thomson cooling across each valve is the model's, not an input: 320 to 304 K at the first letdown, 280 K at the second. No.
- 1Open the ready-made model
Open the "Three-stage condensate stabilization (Soave-Redlich-Kwong)" model in the MaximaLabs workspace — no install, no license. It loads live on the canvas, ready to edit and run.
- 2Confirm the thermodynamics
This process is modeled with the SRK property package over methane, ethane, propane, n_butane, n_pentane, n_hexane — already selected, so the phase equilibrium and enthalpy are physically consistent from the first run.
- 3Review the flowsheet
The flowsheet chains 3× LP SEP, 2× V2. Every block is a real, solvable unit op you can reconfigure on the canvas.
- 4Run the simulation
Click Run. The deterministic solver converges the material and energy balances (recycles included) and fills the live stream table — the AI never invents a number.
- 5Read the results and iterate
Inspect the converged streams, tweak a spec, and re-run — or ask the AI copilot to explain a result or diagnose a failed solve in plain English.
- Thermodynamics
- SRK
- Components
- methane, ethane, propane, n_butane, n_pentane, n_hexane
- Unit operations
- 3× LP SEP2× V2
Opens live on the canvas — free, no install.
Explore the model & flowsheetModeling assumptions & limitations
What this model captures, and what it deliberately does not — from the engineers who built it.
- 1Needed here beyond the obvious: a real stabilizer would reboil the last stage.
Frequently asked questions
- What does the Three-stage condensate stabilization (Soave-Redlich-Kwong) model simulate?
- Wellhead fluid at 60 bar and 320 K — 60% methane with ethane through n-hexane — through a high-pressure separator, a letdown to 15 bar and an adiabatic medium-pressure separator, then to 2 bar and a low-pressure separator, on plain SRK with its shipped kij: the workhorse cubic for hydrocarbons, exactly where it is meant to be used. What it computes: 69 mol/s of HP gas at 76% methane, 10 mol/s of MP flash gas, 5 mol/s of LP gas rich in propane and butane, and 15.9 mol/s of stabilized condensate carrying 0.2% methane and 2.2% ethane — the light ends that would otherwise vent from a tank. The Joule-Thomson cooling across each valve is the model's, not an input: 320 to 304 K at the first letdown, 280 K at the second. No.
- Which thermodynamic method does it use?
- The SRK property package, over methane, ethane, propane, n_butane, n_pentane, n_hexane — already selected. You can switch the method on the canvas before running.
- Which unit operations are in the flowsheet?
- It chains 3× LP SEP, 2× V2. Every block is a real, solvable unit operation you can reconfigure, add to, or remove.
- Do I need to install software or buy a license?
- No. Three-stage condensate stabilization (Soave-Redlich-Kwong) runs entirely in your browser on MaximaLabs — free, no install, no license. Open the model to load it live and run the deterministic solver.
More guides like this
Gas-condensate LNG train: condensate, LPG and LNG
The LNG plant that is also a liquids plant, at real capacity: this is one 4.4 Mtpa train (a two-train plant is two of these), not a scaled-down sketch. A condensate-rich field arrives by trunkline as a two-phase stream: the slug catcher drops ~20 mol% of it out as raw condensate before a single molecule reaches the cold end, and the plant then runs two trains side by side off one feed. Liquids: the raw condensate is let down to an MP flash that strips the dissolved methane (without it the stabilizer's shortcut total condenser tries to condense methane at 8 bar, which is not a real stabilizer overhead), then stabilized to a C₅/C₆ product. Gas: sweetened and dried, chilled to 245 K to knock out an NGL cut, and the NGL demethanized and split by a deethanizer / depropanizer / debutanizer sequence into commercial propane (~98 mol%) and butane (~98 mol%) LPG plus a natural-gasoline bottoms. LNG: the lean gas goes to the same APCI C3MR cold end as the 'c3mr-lng-liquefaction' showcase — propane precool, mixed-refrigerant MCHE to 120 K, JT letdown to a 1.5 bar end-flash drum. Five sold products come out of one flowsheet, each a stream the solver computed. Watch the end-flash boil-off: it leaves at ~13 mol% nitrogen against 1 mol% in the feed, because the flash drum is where an LNG train actually rejects its nitrogen — nobody specified that, the flash found it. Dehydration is the real molecular-sieve bed, not a stand-in: a 4A sieve sized by length-of-unused-bed, which is what actually takes the gas to the <=0.1 ppmv the cold box needs — 95 t of sieve on a 5.5 x 5.5 m bed, a 17.5 h cycle and 1.4 MW of regeneration duty, with 0.47 bar of Ergun pressure drop. The AGRU spec is checked against the physics rather than assumed: 99.9% CO₂ removal leaves 33 ppmv, and at the coldest point in the train (115.9 K) the solid-CO₂ solubility limit is 232 ppmv on the measured-data basis — a 7x margin, so the sweetening spec demonstrably clears freeze-out instead of merely looking tight.
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.
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.
Associated gas conditioning
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).
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).
Hydrogen liquefaction with catalytic ortho-para conversion
A Linde-Hampson JT-cycle liquefaction loop for H₂ (the same recycle topology as helium-liquefaction), but H₂'s real liquefaction process needs one more step helium doesn't: normal H₂ feed is ~75% ortho-/25% para-spin-isomer, while the equilibrium mix at liquid-H₂ temperature is ~99.8% para — liquefying without converting first leaves the ortho fraction far above its new equilibrium value, and its slow natural relaxation releases heat (the textbook explanation for uncatalyzed LH2 tanks self-boiling). This closes a real gap: (a catalytic cold-box converter, real equilibrium-para-fraction statistical mechanics) existed in MaximaLabs but was never wired into a showcase example — and turned out to also be missing from the backend's unit-type validation catalog entirely (fixed alongside this example,). Precooling to 30 K (deep enough that H₂'s JT effect actually condenses it — verified numerically: 77 K/60 K/45 K precool all give zero liquid yield at 20 atm → 1.3 atm here, since H₂'s JT-cooling window needs real precooling well below LN2 temperature, unlike simpler gases) also happens to sit right where the ortho-para conversion actually matters.