Oct-2022

DWC technology for improved separation and reduced CO2 emissions

The two most important challenges today’s refinery and petrochemical industries are facing from a sustainability point of view are reducing carbon footprints from operation while maintaining a profitability margin by improving the yield of value-added products.

Srinivasulu Kaalva, Chanchal Samanta, Chiranjeevi Thota, Bharat L Newalkar and Ravikumar Voolapalli
Bharat Petroleum Corporation Ltd

Article Summary

Improved separation efficiency plays a key role in increasing product yields with minimum energy consumption, thereby reducing CO₂ emissions. The divided wall column (DWC) concept, which combines the operation of two conventional columns in one shell, is an advanced separation technique that helps improve energy efficiency in the range of 10-30% while reducing capital expenditure and space requirements.

Improved separation efficiency plays a key role in increasing product yields with minimum energy consumption, thereby reducing CO₂ emissions. The divided wall column (DWC) concept, which combines the operation of two conventional columns in one shell, is an advanced separation technique that helps improve energy efficiency in the range of 10-30% while reducing capital expenditure and space requirements.

DWC technology is a very promising separation system. In the last two decades, it has found applications in different industries, especially specialty chemicals, petrochemicals, and refineries. Global specialty chemicals producers are actively implementing this technology in their separation applications. To capture the opportunities in these areas, BPCL has developed its own DWC technology and implemented it successfully in Kochi Refinery, one of the flagship refineries of Bharat Petroleum Corporation Limited (BPCL).

The key features of the technology are:
•    BHARAT DWC (B-DWC) is a novel and patented technology developed by BPCL for naphtha separation based on the DWC concept
•    Based on B-DWC technology, a DWC column was configured for naphtha separation into four different streams
•    B-DWC technology was implemented at Kochi Refinery by modifying an existing conventional three-cut column into a four-cut B-DWC
•    The modified column was successfully commissioned on 11th March 2019, and high-quality separation was achieved

Although the DWC concept is well known, very few global players are licensing the technology due to the design complexity and associated operational challenges. Typically, two conventional columns are required, or more energy (~30%) is needed to achieve separation similar to that obtained in B-DWC. BPCL was the first Indian company to successfully demonstrate DWC technology based on indigenous know-how.

B-DWC technology is a versatile and energy-efficient separation technology, and it can be applied to any separation system that separates three or four products. Due to changes in geopolitics and pollution control strategies in China, India is poised to become one of the major specialty chemicals manufacturers in the world. To meet the future demand for chemicals in India, it is important to use energy-efficient technologies to reduce the cost of production, as well as refinery carbon footprints. In view of this, DWC technology can find a place in the following separation applications:
•    Solvent recovery
•    Extractive distillation
•    API purification
•    Gas separation
•    Refinery separation applications

There is tremendous scope for converting or designing new DWC columns for different types of applications in India. Based on preliminary analysis, approximately 100 separation columns in Indian refineries can be converted to DWC. In addition, due to the competitive price advantage in India compared to other developed nations presently licensing this technology, India can become a global technology provider and earn foreign exchange, as well as provide employment for Indian nationals across the globe.

BPCL has signed an agreement with Engineers India Limited (EIL) to license this technology using the trade name ‘BharatEng-DWC Technology’. BPCL-EIL is advancing to jointly provide end-to-end technology, including process design, internals supply, installation, and commissioning for both greenfield and retrofitting units.

This short article appeared in the 2022 Refining India Newspaper, which you can view HERE