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.

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.

Assay Characterization

TBP/ASTM D86/D1160 crude assay curves are cut into pseudocomponents via Riazi-Daubert (Tc/Pc/MW from NBP+SG), Edmister (acentric factor), Watson K, and a Kesler-Lee ideal-gas Cp(T) — the same pseudocomponent seam any EoS package flashes through.

thermodynamicspetroleumpseudocomponents

Concept

A crude/refinery feed isn't a list of named components — it's a TBP (True Boiling Point) distillation curve plus a specific-gravity profile. Assay characterization cuts that curve into equal-volume pseudocomponents, then regresses each cut's critical properties from just its normal boiling point and specific gravity.

The math

Show the governing equations

T_c,\ P_c,\ MW = f_{\text{Riazi-Daubert}}(NBP,\ SG)

\omega = f_{\text{Edmister}}(T_c,\ P_c,\ T_b)

K_w = \frac{NBP^{1/3}}{SG} \quad \text{(Watson characterization factor)}

Kesler-Lee then supplies an ideal-gas Cp(T) for each cut so it flashes like any other pseudocomponent through the same EoS seam.

Execution

The crude distillation flowsheet in the MaximaLabs workbench

The example as it opens in the workbench. Click to enlarge.

Launch in MaximaLabs Workspace

ASSAY_INFEASIBLEA petroleum assay curve could not be characterized into pseudocomponents (e.g. a non-monotonic TBP curve).