Title : Addressing NSU/NHT/CCR light naphtha cooler leak without production downtime: A strategic approach to unit asset integrity, emissions mitigation, and cooling tower safety at HPCL Mumbai refinery
Abstract:
Objectives/Scope:
This paper presents a strategic, environmentally conscious response to a critical leak in the light naphtha cooler (101E1002) within the NSU/NHT/CCR unit at HPCL Mumbai Refinery. The incident posed significant risks not only to operational continuity but also to environmental emissions and cooling tower integrity. The objective was to implement an innovative mitigation plan that preserved continuous production, prevented hydrocarbon ingress into the cooling water system, and minimized environmental emissions, all without requiring a unit shutdown or feed rate reduction.
Methods/Procedures/Process
Operational Context and Leak Diagnosis:
The GFEC section of HPCL Mumbai Refinery, including NSU/NHT/CCR, NHT/ISOM, and PRIME G units, plays a vital role in Motor Spirit (MS) production. In the NSU, straight-run naphtha is fractionated into light and heavy cuts. The excess light naphtha (~35 TPH) is typically routed to storage via the seawater-cooled exchanger 101E1002.
Detection of a hydrocarbon leak in 101E1002 raised immediate concerns regarding environmental emissions and cooling water contamination. Given the lack of isolation mechanisms, conventional corrective measures—such as unit shutdown—were not viable without incurring high operational and environmental costs.
Strategic and Environmentally Focused Mitigation:
A process-engineered solution was implemented by rerouting excess light naphtha through the benzene reduction side draw stream using the alternate cooler 101E2001. This eliminated dependence on the leaking exchanger and enabled immediate emission control and environmental protection. The approach involved:
- Management of Change (MOC) with detailed engineering validation to ensure emission-safe operation and process integrity.
- Real-time adjustments in side draw flow rates to balance benzene levels and avoid process inefficiencies or additional emissions.
- Continuous environmental and operational monitoring to ensure emissions compliance and system stability.
Results/Observations/Conclusions:
The rerouting strategy was successfully implemented within a seven-day window, achieving the following outcomes:
- Uninterrupted MS production, avoiding estimated losses of INR 123 crores.
- Prevention of hydrocarbon ingress into the cooling tower, effectively eliminating a potential source of volatile organic compound (VOC) emissions.
- Maintenance of air and water quality compliance by mitigating unplanned hydrocarbon release into environmental streams.
- Enhanced operational flexibility and reduced emissions through optimized benzene management.
This case demonstrates how proactive engineering and environmental stewardship can converge to resolve refinery integrity issues without sacrificing production or sustainability goals.
Novel/Additive Information:
The intervention highlights a replicable, emissions-conscious framework for managing equipment integrity failures in hydrocarbon facilities. By strategically realigning flow paths and maximizing existing infrastructure, the solution not only ensured process safety but also supported HPCL’s broader environmental performance targets. The methodology offers valuable insights for refineries seeking to align reliability initiatives with emissions mitigation and environmental compliance imperatives.
Audience Takeaway:
- This pragmatic approach serves as a valuable reference for troubleshooting complex issues in refinery operations.
- The solution streamlines the task for process designers by offering a proven, field-tested alternative.
- The audience gains insights into effective troubleshooting methodologies that avoid production downtime.
- The strategy demonstrates how continuous production can be maintained while adhering to stringent environmental regulations.
