Ethylbenzene synthesis — a PENG-ROBINSON process flowsheet
Benzene alkylation with ethylene (exothermic, 98% ethylene conversion) followed by a recovery column — 100% EB bottoms. From the ChemSep casebook (AIChE J 57, 655).
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- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 3 unit operations modeled: RX, COOL, Bzcol.
- Focus areas: Alkylation, Reactor + column, Ethylbenzene.
- Thermodynamics
- PENG-ROBINSON
- Components
- ethylene, benzene, ethylbenzene
- Unit operations
- RXCOOLBzcol
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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("ethylbenzene-synthesis")
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
2,6-Xylenol from phenol methylation
Liquid-phase methylation of phenol with methanol at 250°C/150 bar over a selective ortho-methylation catalyst, per US Patent 3,707,569. At 50% single-pass phenol conversion the reported selectivity is 70% to o-cresol and 25% to 2,6-xylenol (the further-methylated product) — modeled here as two sequential fixed-conversion reactors (phenol → o-cresol, then o-cresol → 2,6-xylenol) approximating that split, followed by a distillation separating the light methanol/water from the phenolics. The five-component side-draw column sits in the same successive-substitution residual plateau documented for the light-ends-train and DME-synthesis examples — it returns a physically reasonable partial profile rather than a clean converged status.
Cumene production (benzene alkylation)
Benzene and propylene alkylate over a fixed-conversion reactor to cumene (isopropylbenzene, the feedstock for phenol/acetone via the Hock process); a downstream column recovers unreacted benzene overhead for recycle-quality purity while cumene leaves the bottoms. Luyben, Ind. Eng. Chem. Res. 2010, 49, 719.
Butene/isobutane alkylation
Sulfuric-acid alkylation of butene with excess isobutane produces high-octane alkylate gasoline blendstock; a conversion reactor stands in for the acid-catalyzed carbocation chemistry (a literal acid/hydrocarbon settler would need H₂SO₄ electrolyte thermodynamics this package doesn't carry — out of scope, same as the reactor already being a stand-in for the chemistry itself), and a deisobutanizer-style column recovers unreacted isobutane overhead. The high isobutane:olefin ratio real alkylation units run is maintained almost entirely by recycling that isobutane back to the reactor feed — closed here as a real Wegstein-converged tear loop, with only a small makeup feed replacing what the reaction actually consumes, rather than the previous version's isobutane leaving as an unrecycled product. Luyben, Principles and Case Studies of Simultaneous Design, Wiley (2011); Ind. Eng. Chem. Res. 2009, 48, 11081.
Integrated styrene chain: benzene to styrene monomer
The full two-step styrene chain connected as one flowsheet rather than two standalone process snippets: benzene alkylated with ethylene to ethylbenzene, purified in a recovery column, then fed directly to the dehydrogenation reactor that makes styrene monomer. The unreacted ethylbenzene the dehydrogenation column recovers is reported as its own product stream rather than recycled back onto the alkylation feed (an honest simplification — closing that loop needs a torn-recycle edge back into ALKCOL, which the plant does but this flowsheet does not).
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.