Dividing Wall Column Technology

A DWC places a vertical partition inside a single distillation shell, so one column can separate a multicomponent mixture into three or more high-purity product streams — work that conventionally requires two or more columns in series. The concept has existed since the mid-1940s and keeps gaining ground because it delivers lower capital investment and lower operating costs than conventional arrangements.

DWC Prime is DWC Innovations’ proprietary dividing wall column technology, built on innovative in-house designs that make the economics even more lucrative. It covers a wide spectrum of implementations — from single-wall, three-product columns to dual and multi-wall DWCs and multi-column networks — including complex DWCs that deliver ppm-level product purities, all under single-point accountability from design through delivery.

It varies with the duty, but the pattern holds: because one DWC does the work of several conventional columns, most revamps land in the 20–50% range on combined operating and capital cost. Those savings come from three levers together — fewer columns and a smaller plot, lower energy use, and changes confined mostly to internals rather than new equipment. The application figures above show where they have landed on real projects.

It is firmly commercial. The DWC Innovations team has commercialized more than 25 dividing wall columns worldwide over two decades of refining and petrochemical projects — including the world’s first commercial dual DWC (BPCL Mumbai), a turnkey naphtha-splitter dual DWC (MRPL Mangalore), and a dual DWC deisohexanizer (CPCL).

Both — but revamps are a particular strength. An existing side-cut or naphtha-splitter column can be converted to DWC to lift capacity by more than 40%, with changes limited mainly to internals. Deisohexanizer (DIH) revamps typically pay back in 2–12 months while increasing isomerization-unit throughput by 20%+.

The biggest wins are across the naphtha block, isomerization units, and petrochemical service — naphtha splitters, deisohexanizers, reformate and aromatics feed splitters, and depropanizer/propylene splitters. DWC Prime also debottlenecks downstream units such as Isomerization, CCR, Para-Xylene, and Aromatics Recovery (ARU).

Yes. A DWC Prime revamp can reduce carbon disulphide (CS₂) in petrochemical naphtha to below 1 ppm without building a dedicated new unit — using the existing column footprint to meet tightening product specifications.

No. A modern DWC is designed to be as controllable as a conventional column. We set up the control scheme up front using dynamic simulation — from standard loops to advanced process control where the duty calls for it — so the column holds purity and stays stable across its full operating range.

The whole system around it. A typical scope runs from feasibility and process modelling through basic and detailed engineering, local fabrication of the internals, and project management all the way to installation and start-up — so what you receive is a working unit, not just a set of drawings.

A DWC has one dividing wall inside the shell. A Dual DWC (multi-wall DWC) has more than one, so a single column can handle more complex multicomponent separations. DWC Innovations commissioned the world’s first commercial multi-wall DWC at BPCL Mumbai.

Refining, petrochemicals and chemicals. Typical services include naphtha splitters, depentanizers, deisohexanizers, depropanizers, aromatics feed splitters and solvent purification trains.

When a feed must be split into three or more products, when an existing column is limiting capacity, or when energy and plot space are constrained. In these cases one DWC can replace two or more columns, which is where the largest savings come from.

Up to 50%, because one shell replaces two or more columns together with their reboilers, condensers, pumps and piping.

An EDWC combines extractive distillation, which uses a solvent to separate close-boiling components, with a dividing wall in the same shell. EDWC Prime reduces the number of columns needed for difficult separations.

In a conventional two-column train, the middle component is partly remixed between the columns, which wastes energy. A DWC avoids this remixing and uses one reboiler and one condenser for the whole separation.

Naphtha splitters, depentanizers, deisohexanizers, depropanizers and side-cut columns are typical candidates, especially where an extra product or more capacity is needed from the same shell.

Process flow diagrams, operating data, feed and product analyses, product specifications and the existing column and tray data sheets.