Enhancing Propylene Recovery in a Refinery & Petrochemical Complex

A polypropylene unit within a Refinery and Petrochemical complex, utilizing Novolen™ technology, faced significant operational challenges. As refineries globally are expanding their operations to include petrochemical units within their complexes, optimizing the efficiency and reliability of these units has become paramount.

The system operated with propylene gas at a flow rate of 15,600 kg/hr, with a density of 2 kg/m³ and a viscosity of 0.01 centipoise. Unfortunately, the customer faced substantial propylene losses due to the inefficiency of the existing liquid gas coalescer. This equipment, sourced from another vendor, failed to effectively remove contaminants such as oil and triethylaluminium (TEAL), a liquid catalyst used in polymerization reactions. As a result, the compressor often had to shut down, leading to significant operational and financial repercussions.

The customer lost approximately 4 tons of propylene per hour, which translates to a cost of $625 per ton. Over 208 hours of operation resulted in an annual loss of 832 tons, amounting to a monetary loss of $520,000 solely from product losses. This figure does not consider additional downtime, spare parts, and maintenance costs, which further compounded the financial impact.

Pall proposed a targeted solution designed to address the inefficiencies of the existing coalescer system by utilising 48 x Seprasol® Plus, 40” coalescer elements (99.999% efficiency at 0.3µm aerosol rating, 99.7% @ >0.3µm solids removal rating), housed in a 1500mm diameter filter vessel, downstream of an internal demister pad.

Initial expectations estimated the lifetime of elements to be around 3 months, given the clean differential pressure (DP) of 300 mbar. However, actual performance has shown a longer run length of 6 to 9 months, further enhancing the value of the solution. The solution provided a payback period of less than 6 months. The customer confirmed in writing that the “Pall Coalescer is giving satisfactory performance at downstream and also coalescer elements are giving life of more than 18 months after continuous operation”. 

Conclusion

More recently two other Indian refineries have successfully implemented this system, with the potential for global replication. The customer also placed an additional order for a standby vessel, an uncommon practice for liquid gas coalescers, indicating high satisfaction.

Pall Corporation's innovative coalescer solution not only resolved the immediate operational issues but also delivered substantial financial benefits and improved system reliability. This case study underscores the importance of tailored solutions in complex refinery and petrochemical operations and demonstrates the potential for significant operational improvements and cost savings.

* Novolen PP technology is the industry-preferred technology to produce polypropylene, and is a registered trademark of CE Lummus

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