Rate-based column (two-film) simulation

feed -> distillate + bottoms (multicomponent Maxwell-Stefan mass transfer)

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Governing equations

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

(\mathcal{N})_j = [K_{OV}]_j\,(K_j\!\circ\! x_j - y_j),\quad [K_{OV}]^{-1} = [k_V]^{-1} + [K]\,([k_L][\Gamma])^{-1}

[\Gamma]_{ik} = \delta_{ik} + x_i\,\partial\ln\gamma_i/\partial x_k \quad(\text{liquid thermodynamic factor; } I \text{ if ideal})

y_j^I = K_j\, x_j^I \quad(\text{vapor-liquid interface at equilibrium})

V y_j = V y_{j+1} + \mathcal{N}_j,\quad L_j x_j = L_{j-1}x_{j-1} + f_j - \mathcal{N}_j

[K_{OV}]\to\infty \Rightarrow y_j \to K_j\!\circ\! x_j \quad(\text{equilibrium limit})

Parameters

rigorous two-film Maxwell-Stefan rate-based column (binary OR multicomponent): n_stages, feed_stage, reflux_ratio, distillate_to_feed|distillate_rate, pressure [Pa]. Each interior stage carries separate bulk vapor/liquid + interface equilibrium; c>2 uses the MS coefficient matrices with the liquid thermodynamic factor [Gamma] from the activity model (set ideal_thermo_factor to force [Gamma]=I). energy_balance (binary) solves variable non-CMO flows + separate vapor/liquid stage temperatures. Tune via mass_transfer_scale [large = equilibrium], n_gas_tu/n_liq_tu, or efficiency_method (aiche | chan_fair for trays; onda for a PACKED bed — then set packing [random_25mm|random_50mm|pall_25mm|structured_250|...], packing_material [metal|ceramic|plastic|carbon], packing_hetp [m])

Example flowsheets that use it

Rate-based distillation (Maxwell-Stefan, ChemSep-style)

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Rate-based column (two-film) simulation

Governing equations

Parameters

Example flowsheets that use it

Rate-based distillation (Maxwell-Stefan, ChemSep-style)

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