A process simulator that runs in your browser: steady-state, pressure-driven and dynamic flowsheets, rigorous thermodynamics, and an AI copilot that builds and explains them. There is nothing to install.

Does the AI calculate the results?

No. The copilot proposes a flowsheet or a change and explains it; the deterministic solver computes every temperature, duty and composition you see. A flowsheet from the copilot that does not validate is not applied.

Will it feel familiar if I have used Aspen Plus or HYSYS?

That is the intent. The workbench has a ribbon, an All Items tree, a form for each block and the three run modes — steady state, pressure driven and dynamics — so the habits carry over.

Can it open my Aspen or HYSYS cases?

Aspen Plus .bkp and .apw, HYSYS .hsc and DWSIM files import with deterministic parsing and a report of what was recovered. A HYSYS .hsc import is partial — unit names and types, not connectivity — and the report says so.

Which thermodynamic models are included?

Peng-Robinson and SRK (including Gᴱ mixing rules), NRTL, UNIQUAC, UNIFAC, PC-SAFT, CPA, GERG-2008, electrolyte NRTL, Pitzer and the IAPWS steam tables — more than 30 property packages in all.

Yes. The Python SDK (pip install flowsim-sdk) creates, runs and reads simulations, and its results are the same objects the canvas shows.

How much does it cost?

It is free to start, with no credit card. Paid plans add higher limits and team features; the pricing page has the details.

Fluosilicic acid recovery (F scrubber) simulation

gas + water -> cleaned gas, H2SiF6 product, silica, excess water

Simulate it free Browse example flowsheets

Governing equations

The exact equations the solver works for a fluosilicic acid recovery (f scrubber) — the same math shown in the app's "Theory" panel, not a black box.

\eta_F = 1 - (1 - e)^{N}

SiF_4 + 2\,HF \rightarrow H_2SiF_6

3\,SiF_4 + 2\,H_2O \rightarrow 2\,H_2SiF_6 + SiO_2

w_{FSA} = \frac{\dot m_{H_2SiF_6}}{\dot m_{H_2SiF_6} + \dot m_{H_2O,prod}}

y_{H_2O,out} = \frac{P_{sat}(T)}{P}

Q = \sum_{out} F_i h_i - \sum_{in} F_i h_i,\quad h_i = \Delta H_{f,i}^{\circ} + \int_{298.15}^{T} c_{p,i}\,dT

$\eta_F$: fluorine removed from the gas [-]
$e$: removal per stage [-]
$N$: absorber stages [-]
$w_{FSA}$: product strength, mass fraction H2SiF6 [-]
$\dot m_{H_2SiF_6}$: fluosilicic acid formed [kg/s]
$\dot m_{H_2O,prod}$: water in the product [kg/s]
$y_{H_2O,out}$: water mole fraction in the cleaned gas [-]
$P_{sat}(T)$: water vapour pressure at the scrubber temperature [Pa]
$P$: gas pressure [Pa]
$Q$: duty to hold the scrubber temperature [W]
$F_i$: molar flow [mol/s]
$h_i$: molar enthalpy on the formation basis [J/mol]
$\Delta H_{f,i}^{\circ}$: standard enthalpy of formation [J/mol]
$c_{p,i}$: heat capacity [J/(mol K)]

Parameters

SiF4/HF in a gas absorbed into water as fluosilicic acid (3 SiF4 + 2 H2O -> 2 H2SiF6 + SiO2; SiF4 + 2 HF -> H2SiF6, the HF reacting first). absorber_stages [-] (default 1); stage_efficiency [-] (fluorine removed per stage, default 0.90, the EFMA BAT booklet No. 4 figure for one atmospheric absorber; a vacuum evaporator system recovers 0.83-0.86 in one stage); product_strength [-] (mass fraction H2SiF6 in the product, optional: surplus water leaves through excess_water); temperature [K] (default the water inlet's; the cleaned gas leaves saturated with water at it). Reports fluorine removal, recovery to acid, product strength, silica, water consumed/condensed/evaporated and the fluorine emitted

Example flowsheets that use it

Phosphoric acid plant fluorine recovery: fluosilicic acid from two scrubbers

Open guide

Fluosilicic acid recovery (F scrubber) simulation

Governing equations

Parameters

Example flowsheets that use it

Phosphoric acid plant fluorine recovery: fluosilicic acid from two scrubbers

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