Acetone recovery — batch still vs. continuous column — a NRTL process flowsheet
A spent-solvent stream (60 mol% acetone, 40% water) recovered two ways, so the Analysis panel's Batch distillation (Rayleigh) tool has something to be compared against — it had no curated example, and a batch calculation only means anything next to the continuous alternative.
The flowsheet is the continuous answer: a shortcut column recovering 98% of the acetone overhead and rejecting 98% of the water, giving 59.8 mol/s of distillate at high purity for 4.4 MW of reboiler duty.
The batch answer (Analysis > Batch distillation). Charge 100 mol of the same mixture to a still and boil it down until the pot falls to 10 mol% acetone: you distil 67.4 mol and the average distillate is only 84.2 mol% acetone. That is the Rayleigh result and it is the whole lesson — a simple batch still has one theoretical stage, so the vapour it makes is enriched but never pure, and the composition drifts the entire time. Reaching column-grade purity in a batch needs reflux and cuts (a batch rectifier), or a second pass.
Why the comparison is the point. Batch equipment is cheap, flexible, and right for small or campaign volumes; the column is right when the duty is continuous and purity matters. Having both numbers on the same feed is what makes that a decision rather than a preference.
Modeling assumptions & limitations
- 1The Rayleigh tool integrates the differential mass balance for a binary charge at one theoretical stage — no reflux, no holdup, no column dynamics — and takes its relative volatility from the property package at the stated pressure. The column here is the FUG shortcut, a sizing estimate rather than a rigorous stage-by-stage solve.
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- Rigorous NRTL thermodynamics, solved by the same engine every simulation runs on.
- 1 unit operations modeled: COL.
- Focus areas: Batch distillation, Rayleigh, Solvent recovery, Shortcut column.
- Thermodynamics
- NRTL
- Components
- acetone, water
- Unit operations
- COL
Opens in a new tab, loaded straight into the app — no setup.
Read the step-by-step guideReproduce this exact result from Python — the real client.get_example() → run_and_wait() path, not a mockup.
from flowsim.sdk import FlowSimClient
client = FlowSimClient()
example = client.get_example("acetone-recovery-batch-vs-column")
sim = client.create_simulation(example["title"], example["flowsheet"])
result = client.run_and_wait(sim["id"])
print(result["status"]) # "converged"
streams = client.streams(sim["id"])Related models
Acetone–water distillation
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