(157e) Revamping a Conventional Naphtha Splitter to a Dividing Wall Column at a Major Southeast Refinery

The existing Naphtha Splitter is a conventional side draw column; it splits the feed coming from the bottom of an FCC Unit De-Pentanizer into three streams: Naphtha Splitter Light Cut, Naphtha Splitter Middle Cut and Naphtha Splitter Heavy cut.

The heat duty to the column is provided by two reboilers: Upper and Lower reboiler, while the top condensation system provides the cooling duty to generate the required internal reflux. The feed is pre-heated at the pre-heat exchanger by mean of the side cut draw off before entering the middle section of the tower.

A poor fractionation was occurring between the adjacent cuts resulting in a huge overlap, particularly between the Middle and the Heavy Cuts.

To overcome these limitations, it was decided to convert the tower into a Dividing Wall Column.

To successfully convert a conventional Naphtha Splitter to a Dividing Wall Column, a deep knowledge of the process is a must, but certainly not enough. It is also crucial to fully comprehend the equipment being used, their mechanisms of operation, their limitations, and capabilities. This includes, among others, the mass transfer components being used in the baffled sections of the tower: half-moon shape fractionation trays, and half-moon shape packed beds, and the associated distributors.

This paper will describe the revamp of a conventional Naphtha Splitter into a Dividing wall column from the conceptual design to the commissioning of the revamped equipment and the operating data after the revamp