RIL, IIP jointly develop benzene recovery process; file for patent

Reliance Industries Ltd and Indian Institute of Petroleum (IIP) have jointly filed a patent for a new process for Benzene Recovery, that has helped to create a strong intellectual property (IP) and ''freedom to operate'' assurance.

Engineering and consulting major Technip was selected as detailed engineering contractor (DEC) for the new process named Benzene Recovery Unit (BRU).

RIL undertook the construction and the  commissioning of BRU and on 23 May 2016, the on-specification raffinate product (less than 0.2 vol-% benzene) was sent to storage for blending and sales.

With this technology development, RIL and IIP have now joined the league of technology pioneers and have received several enquiries for licensing the technology, says an RIL release.

RIL and Indian Institute of Petroleum (IIP) Dehradun had, in 2011, signed an agreement to co-develop an extractive distillation process using a robust solvent that will not degrade appreciably in the presence of difficult species and contaminants, and meet the following:

• 0.2 vol-% benzene or less in raffinate (return stream to gasoline)
• 99 vol-% or higher benzene recovery (extracted and upgraded to cyclohexane grade

It was understood that robust and selective solvent will improve unit operation and performance resulting in higher reliability and availability of the unit.

RIL-IIP team did several experiments in the laboratory and pilot plants, and established that selected solvent is robust and meets the required performance criteria. Based on pilot plant data, process scale-up and process design optimisation was done. All this data and work was used to develop technical information package (TIP) containing simplified process flow diagram, heat and mass balance and preliminary data sheets for critical equipment.

RIL Jamnagar refinery has two of the world's largest fluid catalytic cracker (FCC) units. The light naphtha produced from these units is the major contributor of benzene in the gasoline pool.

Due to health and environmental concerns, there has been an increasing pressure on refiners around the world to reduce the amount of benzene and other hazardous air pollutants in the gasoline pool. In 2011, under Mobile Source Air Toxics (MSAT) gasoline fuel programme, Environmental Protection Agency (EPA) in the USA required refiners to meet an annual average gasoline benzene content standard of 0.62 volume per cent (vol-%) for all of their gasoline, both reformulated and conventional, nationwide. It was evident that, in the near future,  Europe and the rest of the world will also impose lower limits on benzene content in gasoline.

In 2011, RIL started to evaluate available technologies to remove benzene from FCC Light naphtha. All available and the claimed proven technologies at that time had the following;

• Higher capital and operating expenditures
• Loss of value due to significantly lower benzene recovery
• Loss of octane barrel due to loss of high-octane olefinic compounds

Also available extractive distillation technology that used solvent to extracts benzene from FCC light naphtha was not proven commercially. It is very challenging to extract benzene from light naphtha using solvent because of its rapid degradation by polymerisation in the presence of reactive species such as olefins and di-olefins, and contaminants such as sulphur, nitrogen, chlorides, oxygenates, etc.