A large Canadian refinery was performing risk assessments to identify personnel, environmental, and operational hazards. This work was being completed according to a schedule, and each year a new unit was to be evaluated. The challenge for them was how to use Process Hazard Analysis (PHA) methodologies for an effective analysis appropriate to the unit to be studied.
To quickly identify any compliance gaps and conduct risk analysis for each unit, our team used Process Safety Office® PSMPro™ software from our partner ioMosaic. A top down fault tree analysis was used for the risk assessment of the refinery’s cooling water systems and acid gas/sulfur recovery systems. The PHA of the hydrofluoric acid (HF) alkylation unit was completed in accordance with RP751, as recommended by the American Petroleum Institute (API), which required the use of the Hazard and Operability (HAZOP) methodology. For other refinery units such as the crude tower, hydrocracker, and BTX unit, a combination of the HAZOP and What-if/Checklist methodologies was utilized. The hazard analysis was followed by consequence analysis of the identified high-risk release scenarios, using Process Safety Office® SuperChems® software, also from our partner ioMosaic. The team determined the impact of fire, explosion, toxic dispersion, etc., identified factors affecting the impact, and created an appropriate model to estimate the magnitude of those impacts.
The team met the refinery's risk management goals by delivering a quality risk assessment. They were able to quickly adapt the PHA to each particular unit's requirements and save costs. The compliance gaps were identified, and the status of recommendations and/or action items was tracked. Our approach has made it far simpler for the refinery to revalidate in the future.