Build with AI: from a description to a solved flowsheet
Type what you want the way you would brief a colleague: the feed, its make-up, and what each unit should do. Anthropic’s Claude looks up the components, checks its plan against the simulator’s own rules, and shows you the whole plan. Nothing changes on the flowsheet until you press Build. Then the plan is drawn, connected and solved as one undo step, and every number comes from the simulator’s own solver.
A gas plant from a description, in two minutes
A natural gas conditioning plant on Peng-Robinson: an inlet separator, a gas/gas exchanger, a chiller and a cold separator, with the cold gas returning through the exchanger as sales gas. One paragraph of plain English, no drawing.
- Claude found all ten components and planned the fluid package, every stream and every unit, with its assumptions written out
- It saw the loop through the gas/gas exchanger and closed it with a recycle on an estimated tear stream
- Build drew and connected it and ran Solve All: solved in 10.3 s, every unit OK
- “Lower the chiller outlet to −30 C” changed one unit and the loop’s estimate, and the NGL rose from 9,478 to 12,537 kg/h
Captioned, no sound needed. 2 min 8 s. Three waits are shortened, and the captions say where.
Describe, read, build, change
Every picture below is from the run in the video. Open the panel from Flowsheet > Build with AI or the Build with AI button beside Solve All.
Say what you want, with the numbers you know
Give the flows, temperatures, pressures, compositions and the property method you have. Where you leave something out, Claude chooses a sensible engineering value and lists it as an assumption, and if something that changes the design is missing, it asks, offering the value it would use.
The request in the video, as typed:
Build a natural gas conditioning plant on Peng-Robinson. Feed: 50,000 kg/h of natural gas at 30 C and 70 bar, mole %: methane 80, ethane 7, propane 5, i-butane 1.5, n-butane 2, n-pentane 1, n-hexane 0.8, n-heptane 0.7, CO2 1, nitrogen 1. Remove the free condensate in an inlet separator. Pre-cool the gas in a gas/gas exchanger against the cold gas from the cold separator, with a 10 C minimum approach, then chill it to −20 C and separate the condensed NGL in a cold separator. The cold gas returns through the exchanger as sales gas.
The whole plan, before anything is built
A summary of what the plan builds and why, the assumptions Claude made, the fluid package, the feed streams and every unit with its streams and specification. Before you see it, Claude has checked it against the same rules Build uses: an unknown component, a missing outlet, a stream that already feeds another unit, two specifications on one unit or mole fractions that do not add up to 1 are caught and corrected first.
To change the plan before building it, say what to change; a new plan replaces it.
One press: drawn, connected, solved
Build checks the plan once more against the flowsheet as it stands, makes the fluid package, adds every stream and unit, connects them, writes their specifications and lays them out left to right in flow order. Then it runs Solve All, exactly as the toolbar button does.
All of it is one undo step: one Ctrl+Z takes the whole Build away. If a unit ends WARN or FAIL, Claude reads the solve report and proposes a repair, which waits for your Build like any other plan.
Ask for a change in plain words
Claude reads the flowsheet as it stands, your own hand edits and earlier Builds included, and plans only what changes. In the video, “Lower the chiller outlet to −30 C” became a new outlet temperature for E-101 and a new starting estimate for the loop’s tear stream, and nothing else.
Build again and the change is one more undo step. With the chiller at −30 °C the NGL rose from 9,478 to 12,537 kg/h, and the sales gas fell to 32,212 kg/h.
It proposes. You build. The solver decides.
Nothing changes until you press Build
Claude only reads: the flowsheet on screen and your component database. The plan waits in the panel for you to read, change or ignore. Build is the only thing that touches the flowsheet.
The solver computes every number
The results come from the same solver as a flowsheet you draw by hand. Claude never calculates a temperature, a flow or a duty; after Solve All it reads them, as you do.
One undo step
Every stream, unit, connection and specification a Build adds is one undo step, and so is each change. Ctrl+Z takes it back, as it would anything you did by hand.
It never bends your numbers
Claude never changes a value you gave just to make a unit solve. If it cannot work as asked, it says so and why. Some warnings are expected, such as a knockout drum on a dry gas, and it says that too.
A record in the case file
Every request, plan, Build and Solve All result is kept in the case’s build history and saved with the file. Export it as a web page, or delete it before you share a case.
Optional, always
Every flowsheet can still be drawn by hand. Build with AI needs an internet connection and an API key only when you use it.
Units, columns, reactors, loops and blocks
A plan builds with the same unit operations you would place by hand, and connects new units to streams already on the flowsheet.
Unit operations
Heaters and coolers, separators and three-phase separators, valves, pumps, compressors and expanders, mixers and splitters, and heat exchangers specified by duty, an outlet temperature, a UA or a minimum approach.
Columns
Distillation columns, absorbers, reboiled absorbers and refluxed absorbers, by HYSYS’s names. Product purities and recoveries you give become the column’s own design specifications.
Reactors
Conversion, equilibrium, Gibbs, CSTR and PFR reactors, with each reaction checked for an element balance before you see the plan.
Loops, controllers and blocks
Recycles on an estimated tear stream, Adjust and Set controllers, and sub-flowsheet blocks grouped exactly as Group does by hand.
What a plan cannot do yet. It cannot remove anything, change a unit’s connections or a column’s type, or add a unit inside a sub-flowsheet block from outside it (go inside the block and start a new build there). Side draws, pumparounds and tray efficiencies are set in the column’s own view. Claude says so when a request needs any of these.
Your own Anthropic API key
Build with AI uses Claude Opus 5.5, Anthropic’s model, through your own API key: the same key the column’s AI advisor uses, so saving it in either place serves both.
- Requests go from your computer straight to Anthropic and are billed to your account
- Planning and building a flowsheet of five to ten units cost about 5 to 12 US cents in our tests
- A question, or a repair proposed after Build, costs a few cents more for each exchange
- A Claude.ai subscription does not include API use
The AI convergence advisor, for a column that will not converge →
Does the AI calculate the results?
No. Every number comes from the simulator’s own solver, exactly as if you had drawn the flowsheet by hand. Claude proposes the flowsheet; it does not do thermodynamics or compute a result.
Can it work on a flowsheet I already have?
Yes. It reads the flowsheet as it stands, your hand edits and earlier Builds included. A plan can add units connected to streams already there and change the settings of units, controllers and feed streams. It never removes anything or changes a unit’s connections.
What is sent to Anthropic?
Your request, and what Claude reads to plan: the components it looks up and the flowsheet on screen, with its units, streams, specifications and results. After a Build, the solve report goes too, so Claude can propose a repair. Everything goes from your computer straight to Anthropic, under your own key.
Which sheet does it build into?
The sheet on screen when the conversation began: the main flowsheet, or the inside of a sub-flowsheet block you had entered. The panel’s first line names it, and Build waits if you move to another sheet.
Describe your own process
Build with AI is in every copy of version 1.6.2, for Windows and macOS. You bring the API key.