Three-phase column (decanting) simulation

feed -> organic + aqueous distillate + bottoms (heterogeneous azeotrope)

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Governing equations

The exact equations the solver works for a three-phase column (decanting) — the same math shown in the app's "Theory" panel, not a black box.

\text{MESH column (see distillation)} \Rightarrow \text{overhead condensate } z^{D}

\gamma_i^{I} x_i^{I} = \gamma_i^{II} x_i^{II}\quad(\text{iso-activity decant of the overhead, predictive UNIFAC})

\text{organic} + \text{aqueous} = \text{distillate}\quad(\text{an empty aqueous stream reproduces an ordinary column})

x^{reflux} = x^{decanted\ layer}\quad(\text{heterogeneous reflux: outer fixed point until self-consistent})

$z^{D}$: overhead condensate composition leaving the column's top stage
$\gamma_i^{I}, \gamma_i^{II}$: activity coefficients of i in the organic (I) and aqueous (II) layers — UNIFAC, predictive (no fitted binaries)
$x_i^{I}, x_i^{II}$: mole fractions in each decanted layer
$x^{reflux}$: composition actually refluxed to stage 1 — the whole point of the heterogeneous mode: you return one decanted layer, not the mixed condensate

Parameters

same params as distillation; the overhead is condensed and decanted (UNIFAC LLE) into an organic + an aqueous distillate for heterogeneous azeotropes (water + hydrocarbon/alcohol). Outlets: organic, aqueous, bottoms (aqueous empty if the overhead is a single liquid). Reports heterogeneous_stages (miscibility-gap trays). rigorous_stages=true makes the interior MESH three-phase-aware (tie-line vapor in the gap) at extra cost — needed only near a plait point; strongly immiscible systems need only the decant

Three-phase column (decanting) simulation

Governing equations

Parameters

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