Patent benchmark: selective C3 diene/acetylene hydrogenation (US6495732B1) — a PENG-ROBINSON process flowsheet
Real patent replication: US6495732B1's palladium-catalyzed selective hydrogenation of a cracked-gas C₃ stream, removing methylacetylene (propyne) and propadiene down to trace levels while leaving propylene and propane untouched — the patent's own Example 1 feed (82.7 mol% propylene, 2.37% methylacetylene, 1.30% propadiene) reacted here to '>99.5% removal of both dienes/acetylenes, no propylene-to-propane over-hydrogenation' (propane's mole fraction is unchanged before/after — the actual selectivity claim the patent is about).
Modeling assumptions & limitations
- 1The patent discloses conversions/selectivity at specific pilot conditions but no PdO-catalyst rate constants to derive kinetics from, and its real design runs the catalyst as reactive-distillation packing inside one column rather than a separate reactor — this flowsheet uses two fitted-conversion reactors (conversion set to match the patent's own '95-100%' and 'essentially all... removed' language, not independently measured) ahead of the column, a legitimate simplification of the topology, not the kinetics.
178 views 0 forks
- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 2 unit operations modeled: MIX, 2× Hydrogenate Propadiene.
- Focus areas: Patent benchmark, Selective hydrogenation, Catalytic, C3 splitter.
- Verified fast convergence — a real, measured solve time, not an estimate.
- Thermodynamics
- PENG-ROBINSON
- Components
- propylene, propyne, propadiene, propane, h2
- Unit operations
- MIX2× Hydrogenate Propadiene
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("patent-c3-selective-hydrogenation")
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
Patent benchmark: methyl lactate synthesis (CN104628563A)
Real patent replication, not an invented process: CN104628563A's acid-catalyzed lactate-ester route — lactic acid esterified with excess methanol, then purified by vacuum distillation — reproduced here as a continuous flowsheet. The patent's own worked methyl-lactate example reports 98.8% esterification conversion and 99.6% product purity at 120 degC/3h. This flowsheet's reactor conversion is set directly to the patent's reported 98.8% (not fitted); the vacuum column (0.2 atm, matching the patent's vacuum-distillation purification step) then splits the methanol and reaction water off the ester completely — zero methyl lactate leaves overhead — and delivers 97.8 mol% methyl lactate in the bottoms at 389.9 K. The property method is the whole story here, exactly as it was on the sulfolane extractive column. Written on Peng-Robinson, this example did not converge at all: every pair in a methanol / water / lactic-acid / methyl-lactate mixture is hydrogen-bonding, which van der Waals mixing cannot represent, and the column returned a partial profile carrying 2.60 mol/s of methyl lactate out of a column fed 1.98 — 32% more product than the reactor made, a 0.26 component-balance residual. (That wrong profile is where this example's previously-published 98.75% purity was read from; the number was retracted at the test level and is now corrected here.) A plain activity model cannot be used either, for a data reason rather than a physics one: neither lactic acid nor methyl lactate carries a regressed ideal-gas-Cp correlation, and the gamma-phi enthalpy path raises on that where a cubic quietly falls back to a corresponding-states estimate. PSRK is a cubic whose mixing is driven by UNIFAC, so it has both — and it converges to a 2.7e-06 component-balance residual, with methyl lactate and lactic acid each leaving in exactly the amount the reactor made.
Patent benchmark: gas fermentation to single-cell protein (JP2024028821A)
The gas-fermentation process class JP2024028821A describes: hydrogen-oxidizing chemolithoautotrophic bacteria (the patent names Cupriavidus necator and Rhodococcus opacus strains) fixing CO₂ using H₂ as the electron donor to grow single-cell protein biomass. Built here with real physics closing two genuine gaps this session's fact-check found missing: gas-liquid mass transfer (Henry's-law dissolution + a volumetric kLa driving the H₂ dissolution rate) and chemolithoautotrophic growth stoichiometry (McCarty's electron-balance method combining the H₂-oxidation, O₂-reduction, and C₅H₇O₂N cell-synthesis half-reactions) — not a Monod-on-dissolved-substrate shortcut repurposed for a gas feed.
Patent benchmark: enzymatic cannabinoid synthesis (US9359625B2)
Real patent replication: US9359625B2's THCA-synthase-catalyzed conversion of cannabigerolic acid (CBGA) into either THCA or CBCA depending on operating pH — closing the genuine enzyme-kinetics gap this session's fact-check found (only Monod biomass-growth kinetics existed anywhere in MaximaLabs, no Michaelis-Menten). The patent's own disclosed pH-selectivity data anchors this model: it reports 'catalysis at a lower pH... favored THCA... while... neutral pH... favored CBCA,' a ~10:1 THCA:CBCA ratio at pH 5.0, and CBCA dominant at pH 7.0 — fit here as a single-ionizable-group pH-titration switch (pKa_switch=6.0), which reproduces the reported 10:1 ratio at pH 5.0 exactly (that's how pKa_switch was chosen) and gives ~10:1 CBCA:THCA at pH 7.0 (matching the patent's 'CBCA exclusively' qualitatively, not to an exact published ratio, since the patent gives no numeric ratio at pH 7.0 to match). Reactor volume is sized to clear the patent's own disclosed '>20% conversion' commercial threshold (reaches ~25.0% here).
LNG front end and storage: guard beds, tank boil-off, driver limit
The parts of a 5.2 Mtpa LNG train that are not the cold box, and the four questions they answer that no bulk unit can — at real capacity, so the vessel sizes and duties are ones an engineer can check against their own plant. Guard beds: a sulfur-carbon bed takes mercury from 200 to 0.01 µg/Nm³ — the brazed-aluminium limit, because mercury attacks the plate-fin cold box by liquid-metal embrittlement — on a 4.8 m x 6.6 m bed with 4.2 years of life from a capacity balance — inside the 3-5 year window these non-regenerable beds are actually replaced on, which is what a turnaround plan needs. A 4A molecular sieve then dries the gas to 0.1 ppmv, the only route to a cryogenic water spec (a glycol contactor tops out near a −30 °C dew point), on a 4.9 m x 5.1 m bed running a 13.8 h cycle for 1.3 MW of regeneration duty. Storage: the LNG goes to a tank whose boil-off rate comes from a 0.05%/day guarantee but whose boil-off composition comes from a real equilibrium flash — and that is the interesting part, because the vapour leaves at ~11 mol% nitrogen against 1.1% in the feed. Nitrogen and methane are far more volatile at 113 K, so the boil-off is light and the stored liquid weathers heavier: nobody specified that, the flash found it. Recondensing: the boil-off goes back into the send-out LNG rather than to a flare, and the unit reports the LNG:BOG ratio (1999) against the minimum the energy balance demands (3.8), which is the constraint a terminal is actually operated against. The driver: a gas turbine burning plant fuel gas, rated 97.5 MW at ISO conditions, delivers only 84.5 MW at 35 °C — 5.5 MW short of its 90 MW refrigeration load, and flagged as such. That derate is computed from two physical effects (a fixed-geometry compressor swallows a fixed volume so mass flow follows air density, and hotter air costs more to compress), not from a vendor curve, and it comes out at 0.66%/K — mid-band for industrial machines. It is why a tropical LNG train makes less product in summer.
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.
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).