This DWC Innovations whitepaper examines how a dividing wall column can upgrade a refinery’s naphtha pool by revamping an existing depentanizer. The facility needed three separated streams — high-purity iC5 for premium gasoline blending, an nC5-rich cut, and a C6+ naphtha product — all from a single depentanizer originally paired with a naphtha splitter. Sequential distillation and simple side-cut designs both suffered from component remixing, driving up reboiler and condenser duties or compromising purity. The DWC option eliminated this remixing through its internal dividing wall, matching the two-column sequence’s full iC5 recovery and naphtha rate while noticeably lowering combined reboiler and condenser duty.
3Separated product streams
3Design options compared
1Single DWC vessel
iC5Full high-purity recovery
Design options
Three sequences compared
OPTION 01
Install a new deisopentanizer
OPTION 02
Revamp the existing depentanizer to a side-cut column
OPTION 03
Revamp the existing depentanizer to a dividing wall column
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Reported outcomes
DWC matched the two-column sequence’s full iC5 recovery and naphtha rate while lowering combined reboiler and condenser duty — the best balance of yield, purity, and footprint, without the capital and energy penalties of the alternatives.