Alkylation, with the recycle that actually runs it
Butene alkylated with excess isobutane to high-octane blendstock, the unreacted isobutane taken overhead and returned as a genuinely converged tear loop.
The actual dark-mode canvas: butene and makeup isobutane mixed with recycled isobutane, alkylated to high-octane blendstock, and the unreacted isobutane taken overhead in a deisobutanizer and returned to the reactor feed — the recycle is a solved loop, not a dangling stream.
The recycle is the unit
The isobutane:olefin ratio that keeps an alkylation unit selective comes almost entirely from recycle, so it is closed here as a genuine tear loop converged by Wegstein — only a small makeup replaces what the reaction consumes. Scope note: the reactor is a conversion stand-in for the acid-catalysed carbocation chemistry; a literal acid/hydrocarbon settler needs H₂SO₄ electrolyte thermodynamics this package does not carry.
Unit ops shipped for this vertical
Combines multiple streams into one, closing the mass and energy balance.
A specified per-pass conversion on a key component — the shortcut counterpart to the equilibrium and kinetic reactors.
Wang-Henke MESH column solver — the same rigorous solve at any scale.
Stream reactor isobutane:olefin ratio and deisobutanizer overhead composition from the unit's OPC-UA server into this flowsheet's twin comparison — a recycle drifting off ratio is visible against the solved loop long before octane does.
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- ✓Isobutane recycle closed by Wegstein acceleration
- ✓Deisobutanizer solved as a rigorous MESH column
- ✓After Luyben (Wiley 2011; Ind. Eng. Chem. Res. 2009, 48, 11081)