The majority of dividing wall column (DWC) applications in the refining industry consists of stand-alone columns, whether a retrofit or a grassroots column. Functional DWCs, first commercialized in the 1980s, are encountered in naphtha splitters or reformate splitters. Agrawal, 2001 and Asprion et al., 2011 talk about DWC columns for multicomponent separations. Additionally, Yildirim et al., 2011 reviews several DWCs implementations in the industry. In spite of successful stand-alone column implementation, this technology has not been applied on a larger industrial scale to complex refinery units consisting of a network of columns. This paper discusses the application of DWC technology to naphtha hydrotreating (NHT) and isomerization (ISOM) units (Kalita et al., 2018). Most of the columns in these units often operate at high pressures and temperatures that result in a costly and energy-intensive operation. A comparison between conventional NHT/ISOM schemes and DWC integrated NHT/ISOM schemes is presented. The DWC integrated configuration presented is a licensed grassroots unit for a Middle East refinery.
With the demand for such units ramping up in the refining industry, DWCs can revolutionize these process schemes. The benefits of combining the operation of two (or more) columns in such units to create a network of DWCs include lower capital cost due to the lesser number of equipment required. Additionally, DWCs have been shown to lower energy consumption of units by about 20-30% as compared to conventional columns (Dejanovic et al., 2010 and Kiss, 2009). Hence, integrating DWC technology in conventional NHT and ISOM units has the potential to lower the carbon footprint of these units while improving their efficiency and profitability as well.