Conceptualizing Pressure Relief Requirements in the Design Phase: A Modeling Approach Based on Historical Data

In the petroleum refining industry, the price of crude oil and its refined products are highly volatile; influenced by global, regional, and local supply, demand, and regulatory changes. To be economically viable, the refinery must have the ability to transition efficiently and safely among various crude blends and throughput rates to their various units to optimize operation, economics, and consumer market demands. One critical requirement is evaluation of the impact of these potential feed and throughput changes, to determine the adequacy and impact on the existing relief and flare systems. Current (time-consuming) practices include involving pressure relief systems engineers to revalidate the proposed changes on the existing pressure relief and effluent handling systems.

This paper discusses the development of a model that uses data from hundreds of refinery units’ pressure relief studies. The model provides a set of correlations between most processes (operating conditions, feed blends, product properties) and their overpressure relief requirements, based on industry standards and best practices. These correlations provide a powerful tool to determine key operating and safety parameters that control the pressure relief system sizing basis, without the need for detailed pressure relief calculations, during the early conceptual stage of any OPEX or CAPEX project.