Break

Commercial implementation of Dividing Wall Columns (DWC) has been widely successful in the last two decades owing to robust simulation modelling and technology available for the design and operation of these columns. In most cases, the applications have been limited to individual columns with flexible product parameters. This paper discusses the revamp of two columns with DWC technology at the largest refinery in India.

The original design consisted of a naphtha splitter followed by a depentanizer column. Light Naphtha was separated to a mix of C5 cut and C6+ naphtha. The client now had a requirement to produce three products from the light naphtha. These cuts were iC5, C5s followed by C6+ naphtha. Additionally, a spare Reformate Splitter had been identified by the client for a possible revamp to meet the new product specifications.

The paper explores the multiple design scenarios to meet the new design objectives. These include the following:

• Revamp to two conventional columns in an indirect sequence
• Revamp to two parallel side-cut columns
• Revamp to two parallel dividing wall columns.

The pros and cons of the different revamp scenarios are discussed. The paper also illustrates the challenges encountered in this DWC revamp along with the methodology behind the control scheme for the application.