Thought Leadership

This article, co-authored by KBR’s Minaz Makania and Rajeev Ranjan, along with BPCL’s Anish Chakraborty and Naveen V Nair, examines how distillation column revamp within a refinery utilizing KBR’s Distill-Max® technology can result in high return on investment.

A Dividing Wall Column (DWC) sits in the refinery’s separation section, where mixed streams are separated. It works like a smarter, more efficient distillation tower that can do the job of two towers at once, saving both equipment cost and energy.

How? Through advanced distillation technology, DWC enables the separation of feed into three or more high‑purity product streams within a single distillation tower. By integrating what would traditionally require two separate columns into a single shell, a DWC significantly reduces both capital investment and energy consumption for the separation process.

The core feature of a DWC is a vertical partition, or dividing wall, that splits the central section of the column into two parallel zones. The feed enters one of these sections, known as the pre‑fractionation section and results in the following:

• Light components rise through the column and undergo further purification at the top.
• Heavy components flow downward and are stripped in the bottom portion.
• The configuration helps in minimizing the remixing of the remaining medium components resulting in much purer product in a side draw.   

The DWC concept has been known for more than 50 years, with the first patent issued in 1949. However, its commercialization was delayed due to historically low energy costs, a lack of established design procedures, and a general industry preference for conventional column designs.

KBR’s proprietary solution 

In the late 1980s, KBR developed its proprietary DWC technology, Distill-Max®, through pilot-plant studies. Its first industrial implementation was at BP’s Coryton Refinery in 1998, as a revamp of their stabilizer column, which produced a special gasoline blend component. KBR has successfully licensed several grassroots and revamp DWC units globally ever since.

KBR’s Distill-Max DWC technology offers several advantages over conventional distillation column schemes. These include:

• Capital cost savings: Primarily due to a lower equipment count, DWC can reduce grassroots capital costs by ~25-30%. 
• Improved energy efficiency: More than 25% energy savings are enabled compared to traditional sequential column operations.
• Opex savings: An increase in column throughput can be achieved due to better separation efficiency and improved fractionation performance as compared to conventional schemes.
• Reduced plot space: DWC system requires less plot space due to fewer equipment and auxiliaries. 

KBR has commercialized DWC and with its experience and know-how is providing Distill-Max as a complete solution from start of proposal to performance guarantees evaluation or PGTR.  

The energy saving alternative

Dividing wall column (DWC) technology presents a compelling alternative to traditional distillation column schemes, which results in substantial savings in both operating and capital costs.

DWC technology is well-suited for grassroots and revamps applications in various hydrocarbon separation services. DWC revamps may include converting a two-column sequence into a single column DWC, modifying an existing two-product column for an additional side-draw product, and installing DWC to improve fractionation quality in an existing three product conventional column.

With an increasing focus on energy efficiency the global refining and petrochemical industries not only want to remain competitive, but also compliant with regulatory focus on ‘greener energy’ and a reduced ‘carbon footprint’.  DWC technology offers a simple and low-cost solution that aligns with these goals and acts as a key enabler in energy efficiency improvement pursuits. 

It is to be noted that although the Dividing Wall Column concept has been known for over 50 years – the first patent was issued in 1949 – its commercialization was delayed. Factors responsible were historically low energy costs, lack of established design procedures, and a general industry’s preference for conventional column designs.

An ideal choice for grassroots and revamps

Backed by decades of experience in designing and pilot testing of commercial units, KBR is well positioned to offer safe and reliable grassroots and revamp design of existing columns. Besides, the evaluation of the full operating envelope of the column is done by KBR through a rigorous design procedure and development of in-house proprietary thermodynamic data. 

Providing cost-effective, flexible and energy efficient solution for a wide range of multi-component separation requirements in the refining and petrochemical units, Distill-Max is an established DWC technology.

Distill‑Max® continues to stand out as a proven, technically straightforward investment that delivers meaningful value. Whether for grassroots installations or the revamp of existing distillation systems, DWC solutions offer compelling returns and an efficient path to improved operational performance.

This article was published in December issue of the Refining India magazine. Distillation column revamp using DWC technology