How to simulate cstr thermal runaway (arrhenius exotherm)
Adiabatic ethylene oxide hydrolysis to ethylene glycol in a CSTR — the classic reactor-safety teaching case (Fogler). Solves to a safe steady conversion at the design feed temperature; switch to the Dynamic solve mode and step the feed temperature up a few degrees to watch the exotherm and the Arrhenius rate feed back on each other (thermal runaway), self-limited as the reactant depletes.
- 1Open the ready-made model
Open the "CSTR thermal runaway (Arrhenius exotherm)" 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 PENG-ROBINSON property package over ethylene_oxide, water, ethylene_glycol — already selected, so the phase equilibrium and enthalpy are physically consistent from the first run.
- 3Review the flowsheet
The flowsheet chains RX. 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
- PENG-ROBINSON
- Components
- ethylene_oxide, water, ethylene_glycol
- Unit operations
- RX
Opens live on the canvas — free, no install.
Explore the model & flowsheetFrequently asked questions
- What does the CSTR thermal runaway (Arrhenius exotherm) model simulate?
- Adiabatic ethylene oxide hydrolysis to ethylene glycol in a CSTR — the classic reactor-safety teaching case (Fogler). Solves to a safe steady conversion at the design feed temperature; switch to the Dynamic solve mode and step the feed temperature up a few degrees to watch the exotherm and the Arrhenius rate feed back on each other (thermal runaway), self-limited as the reactant depletes.
- Which thermodynamic method does it use?
- The PENG-ROBINSON property package, over ethylene_oxide, water, ethylene_glycol — already selected. You can switch the method on the canvas before running.
- Which unit operations are in the flowsheet?
- It chains RX. 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. CSTR thermal runaway (Arrhenius exotherm) 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
Kinetic CSTR
A continuous stirred-tank reactor with an Arrhenius first-order rate — outlet conversion comes from the kinetics, not a specified value.
Feed-tank level control (live loop)
A feed surge tank holding water at a target level: a level transmitter reads the tank's live inventory and a PID controller trims the upstream feed rate to hold it. Solves steady-state normally (the level loop is a no-op there); open the pid_controller's Live tab ("From canvas") to run the closed loop in real time and watch a setpoint change drain or fill the tank against a live PID.
Heat exchanger startup thermal lag
A hot ethanol-water process stream cooled against cold cooling water in a single counter-current exchanger. Solves the design steady state; switch to the Dynamic solve mode and step the hot feed temperature to see the classic HX thermal-lag response — the exchanger's metal wall smooths and delays the outlet-temperature change instead of tracking the feed step instantly.
Distillation column startup dynamics (feed-rate step)
An 8-stage ethanol-water column at a reduced startup feed rate. Solves the steady state normally; switch to the Dynamic solve mode with weir/level-controlled hydraulics enabled and step the feed rate up (e.g. 6 → 9 mol/s) to watch the bottoms draw genuinely rebalance to the new throughput as the tray inventories fill — a feed-rate disturbance no fixed-hydraulics dynamic model (incl. this same column's own default rigorous mode) can show at all. Honest bound: the vapor traffic is held at its steady-state value in this mode, so the distillate draw (condenser-level-controlled off vapor inflow) does not move for a feed-rate-only step — only the liquid/bottoms side responds.
Polymerization reactor comparison: CSTR cascade vs. tubular (PFR)
The same monomer feed, split 50/50 into two trains at equal total reactor volume: a 3-stage CSTR cascade (each stage blending its own new polymer with the MWD already carried by the stream from the stage before it) versus a single tubular (PFR) reactor. Both converge to a real, different Mn/Mw/PDI — the PFR reaches higher conversion at the same total volume, but its cumulative polydispersity is measurably broader than the cascade's, because chain length drifts continuously with conversion along the tube while each CSTR stage makes its own local production under one fixed monomer concentration. See the 'Polymerization Reactors' docs page for the full reasoning.
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.