How to simulate closed-loop lpg splitter — dual zero-offset pi control
Two independent, genuinely converged integral (PI) control loops in one train, wired on the canvas (transmitter → controller → manipulated unit, not just reported): a feed preheater's duty holds the column feed at its temperature setpoint, and the column's distillate-to-feed split ratio holds the bottoms temperature at its setpoint — a classic temperature-inferred composition control scheme (this solver has no composition transmitter, so temperature is the composition proxy, exactly as most real columns are actually controlled). Both loops reach a genuine zero-offset steady-state operating point via the flowsheet's outer fixed-point iteration (`result.control_iterations > 0`), each report's `measured` equal to its `setpoint`. This is honestly **decentralized SISO PI control**, not simultaneous MIMO DMC (no predictive horizon, no MV/CV interaction matrix, no constraint handling) — that capability lives in the separate live APC/MPC runtime (see the Control Room), not a static flowsheet example.
- 1Open the ready-made model
Open the "Closed-loop LPG splitter — dual zero-offset PI control" model in the MaximaLabs workspace — no install, no license. It loads live on the canvas, ready to edit and run.
- 2Confirm the thermodynamics
This process is modeled with the PENG-ROBINSON property package over n_butane, n_pentane — already selected, so the phase equilibrium and enthalpy are physically consistent from the first run.
- 3Review the flowsheet
The flowsheet chains PH, 2× TT BOT, 2× CTRL BOT, COL. Every block is a real, solvable unit op you can reconfigure on the canvas.
- 4Run the simulation
Click Run. The deterministic solver converges the material and energy balances (recycles included) and fills the live stream table — the AI never invents a number.
- 5Read the results and iterate
Inspect the converged streams, tweak a spec, and re-run — or ask the AI copilot to explain a result or diagnose a failed solve in plain English.
- Thermodynamics
- PENG-ROBINSON
- Components
- n_butane, n_pentane
- Unit operations
- PH2× TT BOT2× CTRL BOTCOL
Opens live on the canvas — free, no install.
Explore the model & flowsheetFrequently asked questions
- What does the Closed-loop LPG splitter — dual zero-offset PI control model simulate?
- Two independent, genuinely converged integral (PI) control loops in one train, wired on the canvas (transmitter → controller → manipulated unit, not just reported): a feed preheater's duty holds the column feed at its temperature setpoint, and the column's distillate-to-feed split ratio holds the bottoms temperature at its setpoint — a classic temperature-inferred composition control scheme (this solver has no composition transmitter, so temperature is the composition proxy, exactly as most real columns are actually controlled). Both loops reach a genuine zero-offset steady-state operating point via the flowsheet's outer fixed-point iteration (`result.control_iterations > 0`), each report's `measured` equal to its `setpoint`. This is honestly **decentralized SISO PI control**, not simultaneous MIMO DMC (no predictive horizon, no MV/CV interaction matrix, no constraint handling) — that capability lives in the separate live APC/MPC runtime (see the Control Room), not a static flowsheet example.
- Which thermodynamic method does it use?
- The PENG-ROBINSON property package, over n_butane, n_pentane — already selected. You can switch the method on the canvas before running.
- Which unit operations are in the flowsheet?
- It chains PH, 2× TT BOT, 2× CTRL BOT, COL. Every block is a real, solvable unit operation you can reconfigure, add to, or remove.
- Do I need to install software or buy a license?
- No. Closed-loop LPG splitter — dual zero-offset PI control runs entirely in your browser on MaximaLabs — free, no install, no license. Open the model to load it live and run the deterministic solver.