One of India’s most adaptable refineries, Bharat Petroleum Mumbai Refinery (BPCL MR) that has contracted with ‘iFluids Engineering to conduct a Rapid Risk Analysis (RRA) study for its De-Aromatized Solvent (DAS) Unit.
OBJECTIVE
Objective of the study is to evaluate the potential risk levels to personnel from unanticipated hazardous material releases caused by accidents involving loss of containment inside the facilities and to show that individual risks fall within the generally acceptable ranges. The goals of QRA are listed below:
- Events with Major Loss of Containment (LOC) and Hazard Identification
- Calculation of failure’s physical effects that includes Estimation of Jet Fire, Pool Fire heat radiation distances, Flammable Gas Dispersion distances, and Overpressure Explosion distances for physical consequences of failure case scenarios
- Analysis of Failure Rates
- Calculation of societal risk and potential loss of life
- Conduct a risk assessment in accordance with the UK HSE risk acceptance criteria to verify that risk can be decreased in accordance with the ALARP principle.
- Suggest risk-reduction techniques to guarantee that all hazards fall into the ALARP or Acceptable zone
Meteorological data used for the study
| Wind Speed | 5m/s & 1.5 m/s |
| Ambient Temperature | 32OC |
| Humidity | 70% |
| Solar Radiation | 0.65 kW/m2 |
| Wind stability class | F & D (5D & 1.5F) |
The Material Used for carrying out the Rapid Risk Assessment for the DAS unit are
- DIESEL
- HYDROGEN
CONCLUSION
Maximum Impact Results – Fire & Explosion
When any source ignites a pressured release (of a flammable fluid), jet fire results. The highest damage distances for Jet Fire was observed for FBR Leak of IS-06 FBV-3011 to HDF Reactor Inlet at 1.5F weather condition. First degree burns can be experienced up to a distance of 491.106 m (4kW/m2), Second degree burns can be experienced up to a distance of 382.789 (12.5 KW/m2) and the Third degree burns (37.5kW/m2) can be experienced to a distance of 314.768 m. A maximum LFL distance of 521.882 m was observed for 100mm Leak of IS-11 – HDF Recycle Gas KOD – at 5D weather condition.
JET FIRES
Early And Late Pool Fire
Early pool fire is caused when the steady state is reached between the outflow of flammable material from the container and complete combustion of the flammable material when the ignition source is available. The discrepancy between the simultaneous complete combustion of the material and the substance’s discharge of material is what causes late pool fires.
When a lot of flammable material is released quickly, late pool fires are prevalent. The highest damage distances for Early Pool Fire was observed for 100mm Leak of IS-12 – HDF Cold Low Pressure Separator at 5D weather condition as 240.9 m. First degree burns can be experienced up to a distance of 240.9 (4kW/m2). Second degree burns can be experienced up to a distance of 192.947 m (12.5kW/m2). Third degree burns up to a distance of 180.03 m (37.5kW/m2).
The highest damage distance for Late Pool Fire was observed for 100mm Leak of IS-12 – HDF Cold Low Pressure Separator at 5D weather condition as 399.601m.
- First degree burns can be experienced up to a distance of 399.601m (4kW/ m2).
- Second degree burns can be experienced up to a distance of 295.942m (12.5kW/ m2).
- Third degree burns can be experienced up to a distance of 270.973m (37.5kW/ m2).
Flash Fire
Accidentally emitted hydrocarbon vapour will disperse in the direction of the wind. A flash fire is likely to happen if a source of ignition locates an ignition source before being dispersed below the lower flammability limit (LFL), and the flame will then return to the leak’s source. A maximum LFL distance of 521.882 m was observed for 100mm Leak of IS-11 – HDF Recycle Gas KOD – at 5D weather condition.
Overpressure Explosion
Overpressure explosion is the result of flammable materials in the atmosphere, a subsequent dispersion phase, and after some delay an ignition of the vapour cloud. The highest damage distances for overpressure was observed for 100mm Leak of IS-07-A – HDF Cold High Pressure Separator at 5D weather condition as 1253.030 m. Possibility of window glasses are broken up to a distance of 1253.030 m. Repairable damage to building and houses can be experienced up to a distance of 614.621 m and pull away of steel frame buildings from foundations and little damage for heavy machines in industrial building shall be suffered up to a distance of 563.573 m
Risk to People
The major goal of this RRA study is to estimate and evaluate the risk posed by process hazards linked with the Mumbai Refinery of BPCL’s De-Aromatized Solvents Unit. The possibility and effects of potential accidental releases occurring in the facility have been described in order to meet the assessment’s aim. Potential scenarios have been identified, evaluated, and reported. Additionally, relevant recommendations have been given as risk mitigation actions based on the assessment’s findings.
Below are the key findings from the RRA study
Location Specific Individual Risk
The likelihood that a person living permanently and unprotected at a given region may suffer an accident within a year. The level of personal risk varies depending on where you are in relation to a specific plant. Among the Risk ranking locations considered, all risk ranking points lies in the ACCEPTABLE Region.
Individual Risk for the people
Independent of population size, the Individual Risk (IR) provides a measure of the risk that will be applicable to each location (in this example, each area, typically). The Individual risk results for the people is concerned the individual contour of 1E-06/Avg.Year, 1E-07/Avg.Year, 1E-08/Avg.Year and 1E-09/Avg.Year extends up to 89.15m, 249.34m, 282.42m and 309.45m in radius from the center of the De-Aromatized Solvents Unit at BPCL, respectively. The Individual Risk Per Annum for the People at the risk ranking locations considered for the study lies in the ACCEPTABLE region.
Societal Risk
A relationship between frequency and the number of people experiencing a specific level of harm in a given population as a result of the manifestation of a specific hazard is provided by societal risk. The results of the investigation support the conclusion that the overall societal risk for the group under consideration is within the ACCEPTABLE range.