Quantitative Risk Assessment for Nayara Energy Limited Refinery

The Nayara Energy Limited Refinery,  located at Vadinar on the west coast of India near Jamnagar in Gujarat is close to the sources of imported as well as indigenous crude oils. Vadinar is an all-weather deep draft port capable of handling very large crude carriers (300000 DWT). Crude oil imported from Middle East, is discharged through a Single Buoy Mooring (SBM) stationed off the coaster site at a distance of about 5 km. An underwater pipeline transfers the crude to onshore storage tanks. The Vadinar complex includes a petroleum refinery, power generation facilities, along with port & terminal, dispatch, marketing and pipeline networks.

Nayara Energy Limited has entrusted iFluids Engineering to carry out the Quantitative Risk Assessment (QRA) study for the Petroleum Refinery of the Vadinar Complex.

The QRA Study has been carried out for the following facilities

  • ISBL-1
    • Crude Distillation & Vacuum Distillation Unit, Sat. Gas Unit (CDU-VDU-SGU-1),
    • Crude Atmospheric & Vacuum Distillation Unit (CDU-2)
    • Product Treaters (Merichem Units- GMU, KMU-1, KMU-2, LMU, UMU-1, UMU-2)
    • Diesel Hydro-desulfurization Unit (DHDS)
    • Fluidized Catalytic Cracking Unit (FCCU-UGSS)
    • Sulfur Recovery Unit, Amine Recovery Unit, Sour Water Stripping Unit (SRU-ARU-SWS)
  • ISBL-2
    • Diesel Hydrotreater (DHDT)
    • Vacuum Gas Oil Mild Hydrocracker (VGOMHC)
    • Isomerization Unit (ISOM)
  • ISBL-3
    • Delayed Coker Unit (DCU) and Pet Coke Handling System
    • Sulfur Recovery Unit, Amine Recovery Unit, Sour Water Stripping Phase-1 Unit
    • Sulfur Recovery Unit, Sour Water Stripping Phase-2 Units
  • ISBL-4
    • Naphtha Hydrotreater (NHT)
    • Continuous Catalytic Reforming Unit (CCR)
    • Hydrogen Manufacturing Unit (HMU-1)
    • Hydrogen Manufacturing Unit (HMU-2)
    • Mini-HMU
  • OS 
    • Products & Intermediates Tankage (PIT) Area
    • Crude Oil Tankage Areas (COT)
    • Dispatch – Road & Rail
    • Jetty
  • CPP & Utilities
    • Captive Power Plant (CPP # 77 MW, Phase-1, and Phase-2 units # Coal-based Power Plants)
    • Utility-1 Base & Expansion (including Air, Liquid Nitrogen, Natural Gas, Acid, Caustic, DMDS, Chlorine, Cooling Tower systems)
    • Utility-2 Base & Expansion (including Acid Gas Flare, Hydrocarbon Flare, LPG Flare, Waste water & ETP systems)

The primary objective of the QRA  is to estimate the potential risk levels for personnel due to accidental release of hazardous materials from loss of containment scenarios from the facilities and to establish that individual risks are within the broadly acceptable regions.

The QRA study consists of the following:
  • Identification of Hazards and Major Loss of Containment (LOC) events
  • Quantification of physical effects of failure case scenarios which includes estimation of Jet Fire and Pool Fire heat radiation distances, Flammable gas dispersion distances, and overpressure explosion distances
  • Estimation of  Failure Frequency
  • Assessment of Societal risk and estimation of Potential Loss of Life
  • Risk assessment to confirm that risks can be mitigated consistent with the ALARP principle according to the UK HSE risk acceptance criteria

The QRA study results provided recommendations for risk reduction measures to ensure all computed risks are in the ALARP or Acceptable Region, which were reviewed and accepted by Nayara Energy Limited.