(4d) Dual Dividing Wall Columns in Operation

Dual Dividing wall columns (DDWC) is an extension of dividing wall technology with multiple wall arrangements in a single shell. These DDWC combines multiple conventional columns i.e., three or more columns into a single shell and produce four or more high-purity products.

This article shares the operating and design experience of two Dual dividing wall columns operating in Asian refineries.

Light Naphtha Isomerization Unit: The project involved the revamp of a conventional three product Deisohexanizer column to a four product DDWC column. Besides producing a new hexane product, the revamp increased the Isomerization unit capacity by more than 20%.

Lubricating Oil Base Stock (LOBS) Unit: This complex DDWC column operating under vacuum used structured packing as internals. The grassroots column produced four grades of lubricating oil in a single column.