Accounting for Dynamic Processes in Process Emergency Response Using Event Tree Modeling

摘要

When a loss of containment of flammable materials occurs in a process plant, competing dynamic processes take place. On the one hand, the established emergency response comes into action, with a pre-planned action sequence. Simultaneously, the initial incident tends to grow in scale, depending on the level of process safeguarding provided, and its reliability. Emergency response plans generally do not account for the dynamics of emergency control versus escalation, which can determine the ultimate course of the emergency. Should escalation occur before the incident is controlled, the safety of emergency response crew is endangered, and there is greater risk of asset damage on a larger scale. This paper outlines a method by which the competing dynamic processes of incident escalation and incident control can be assessed using event tree analysis. Examples of event trees are provided from hypothetical emergency scenarios in an oil refinery. Escalation times for impinging fires, assessed from heatup analysis, are compared with required response times from the emergency crew. Improvements to process safeguarding design and emergency response are identified. Suggestions are made for design enhancements and for making the emergency response plan more robust. The method also allows for improvements in emergency training, and for the development of additional contingency measures.