Ethane steam cracker — a PENG-ROBINSON process flowsheet
A simplified thermal-cracking train: an equilibrium reactor converts ethane to ethylene + H₂ at furnace conditions (1100 K), then a quench, compression, and a cold flash strip the H₂ tail gas before a C₂ splitter separates ethylene product from unconverted ethane. An equilibrium reactor is used here rather than the kinetic reactor because the latter's concentration term always uses a liquid-phase density (a real gap for a vapor-phase reaction at 1100 K) — noted, not fixed, out of scope for this example. The C₂ splitter needs many stages and high reflux since ethylene/ethane relative volatility is modest. From the ChemSep casebook (ethane cracker).
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- Rigorous PENG-ROBINSON thermodynamics, solved by the same engine every simulation runs on.
- 5 unit operations modeled: Crack, 2× Cool2, COMP, SEP, COL.
- Focus areas: Steam cracking, Ethylene, Equilibrium reactor, C2 splitter.
- Thermodynamics
- PENG-ROBINSON
- Components
- ethane, ethylene, h2
- Unit operations
- Crack2× Cool2COMPSEPCOL
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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("ethane-cracker")
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
Naphtha steam cracker: furnace, quench, compression, cryo train
The full ethylene-plant process shape (steam-methane-cracking's headline technology, e.g. Linde's steam cracking line): a fired-heater convection preheat, a three-reactor lumped pyrolysis furnace, a transfer-line-exchanger quench, a primary fractionator pulling off pyrolysis gasoline, two-stage compression with interstage knockouts, selective acetylene hydrogenation, and a cryogenic cold train (cold-flash light-gas rejection, deethanizer, C₂ splitter, depropanizer) delivering four real products — ethylene, propylene, a butadiene-rich C₄ cut, and a pygas/heavy-ends byproduct — plus an H₂/CH₄-rich tail gas and two knockout condensate streams.
Green ammonia synthesis
An equilibrium reactor runs N₂ + 3H₂ ⇌ 2NH₃ on green-hydrogen syngas (Keq illustrative) — the new-energy leapfrog workflow.
Toluene hydrodealkylation (HDA)
Toluene + H₂ react to benzene + methane over an equilibrium reactor (900 K), then a quench, a high-pressure separator, and a letdown-valve-plus-flash stabilizer strip dissolved H₂/methane before the aromatics split — the same SEP-LETDOWN-SEP2 degassing pattern used for methanol synthesis and CO₂-from-natural-gas elsewhere in this gallery. The final benzene/toluene split uses a shortcut separator rather than a rigorous distillation column: even the small H₂/methane trace left after stabilization has a pure-component bubble point far below any real column temperature (H₂ at 1.5 bar: ~22 K), which corrupts the column's initial T-profile guess and the inside-out/Newton MESH solvers land on a physically nonsensical low-temperature root for this feed. A fix narrowed to just that seed was tried and reverted: it also changes the wide-boiling classification and the seed fed into the (otherwise-fine) inside-out solver for other columns, and broke the already-shipped methanol-synthesis example — the same cross-example fragility already hit twice this session trying to patch the shared thermo core, so it's noted honestly here rather than chased further. From the ChemSep casebook (toluene HDA).
Ammonia synthesis loop (Haber-Bosch, ChemSep casebook)
The classic industrial ammonia loop: fresh syngas joins recycled unconverted gas, reacts over an equilibrium reactor (N₂ + 3H₂ ⇌ 2NH₃) at synthesis conditions, is chilled to condense high-purity liquid ammonia, and the remaining vapor splits into a recycle (back to the loop) and a purge — the purge exists specifically to bleed off the inert argon a single-pass reactor could never consume, which would otherwise concentrate in the recycle forever.
Electrically heated ethane cracker (Linde/BASF/SABIC STARBRIDGE concept)
The same ethane-to-ethylene thermal cracking chemistry as ethane-cracker, but with the furnace's radiant-coil heating supplied by an electric heater instead of a fuel-gas-fired one — the real distinguishing feature of Linde's STARBRIDGE technology (demonstrated at industrial scale with BASF and SABIC at Ludwigshafen, 2024): resistive heating elements replace burners, transferring heat to the process coils by radiation 'in a configuration similar to conventional furnaces,' eliminating the furnace's own combustion-derived CO₂ emissions (upstream grid emissions aside). Modeled here as a plain electric heater node (no fuel-gas inlet, no flue gas, no combustion stoichiometry) in place of fired_heater's combustion-fired duty — the honest difference this technology actually is: identical process-side thermal duty and cracking chemistry, a different (electric) heat source with no direct-combustion byproduct stream. Linde's own proprietary heating-element/coilbox design, materials, and thermal efficiency figures are not published and are not fabricated here; the furnace's computed duty is a genuine energy-balance result (electric heater → real Q required to bring the feed to cracking temperature), not a marketing number.
Oxidative dehydrogenation of ethane to ethylene + acetic acid (EDHOX concept)
Linde's EDHOX technology co-produces ethylene AND acetic acid from ethane and oxygen in one catalytic step (a proprietary mixed-metal catalyst in a multi-tubular salt-cooled reactor), with combined ethylene+acetic-acid selectivity published above 93% and the CO₂ by-product of over-oxidation recovered pure (no nitrogen dilution, since the oxidant is pure O₂, not air). Modeled here as three chained fixed-conversion reactors on real, exactly mass-balanced reactions: the main dehydrogenation (C₂H₆ + 0.5 O₂ → C₂H₄ + H₂O), the acetic-acid co-production path (C₂H₆ + 1.5 O₂ → CH₃COOH + H₂O), and a minor full-oxidation loss path (C₂H₆ + 3.5 O₂ → 2 CO₂ + 3 H₂O) accounting for the un-selective balance — the same 'illustrative, not fitted' posture as the naphtha cracker's furnace, since Linde's catalyst kinetics are proprietary and not published. The per-reaction conversions here are tuned to reproduce the one real published number (>93% combined selectivity: this flowsheet computes ~96%), not an assumed per-pass ethane conversion, which Linde doesn't publish.