Non-Isothermal CSTR: Reactor Ignition & Extinction

Feed & Cooling

Feed flow rate Q 1.20 m³/min

Feed temperature T₀ 320 K

Feed concentration C_A0 1.00 kmol/m³

Coolant temperature T_c 300 K

Reactor State

warming up…

Reactor temp T

300.0 K

Residence time τ

0.83 min

Outlet conc. C_A

1.00 kmol/m³

Conversion X

0.0%

Rate constant k

—

Sim time

0.0 min

How it works

A continuous stirred-tank reactor (CSTR) is assumed perfectly mixed: everything inside the tank is at the same concentration and temperature as the outlet stream. Feed enters at flow rate Q, reacts irreversibly A → B, and the exothermic heat of reaction is removed through a cooling jacket at temperature T_c.

Mass balance:   dC_A/dt = (C_A0 - C_A)/τ - k(T)·C_A
Energy balance: dT/dt   = (T0 - T)/τ + (-ΔH)·k(T)·C_A/(ρCp)
                          - UA·(T - T_c)/(V·ρCp)
Arrhenius:      k(T) = A·exp(-Ea/(R·T))
τ = V / Q  (space time, min)

Q, T₀, C_A0, T_c — the four independent variables an operator actually controls on a real reactor.
Because k(T) grows exponentially, this system can have up to three steady states for the same feed conditions: a cold "extinguished" branch (low conversion), a hot "ignited" branch (high conversion), and an unstable middle branch between them.
Perturb nudges the current temperature a few degrees to show the reactor snapping back to its stable branch — or, near the boundary, jumping to the other one (reactor ignition/extinction, exactly as seen in real exothermic-reactor runaway incidents).
Tank colour and the flow-particle speed in the pipes track T and Q live; the impeller keeps the "perfectly mixed" assumption visible.

Cold / low conversion Hot / high conversion

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