A major petroleum company recently increased production capacity and required an analysis of its existing relief systems to validate performance and design. As a result of increasing production capacity and debottlenecking studies, several refinery units were found to be operating at charge rates higher than the design basis for the relief systems documentation. The documentation and calculations needed to be reviewed and revised to ensure the systems were adequately protected.
With a thorough understanding of the processing units and their relief systems, the ioMosaic team compared the new heat and energy balances with the previous operations, studying and evaluating for compliance. After identifying variances in the operating conditions and fluid compositions, ioMosaic reviewed the overpressure scenario applicability rationale for all overpressure scenarios to identify those that were dependent on the charge rate and those that would be impacted by the variances in operating conditions and compositions. Overpressure scenarios and relief loads for critical relief devices were included.
The relief system adequacy for the rate dependent scenarios was then quantified and the documentation updated. For all systems affected by the increased charge rate, the common mode failure scenarios were updated, and the flare system hydraulics and network equipment performance evaluated. The flare system evaluation included an assessment of emergency depressuring loads.
The existing relief and flare systems were found to provide adequate overpressure protection for the increased charge rates. The relief systems design report was compiled using Process Safety Enterprise® Emergency Relief System Design Workflow, providing to the client electronic documentation for revision control and also a hard copy report to supplement their existing design data library.