(47aw) An Innovative Work Flow for Performing Overpressure Protection Analysis Incorporating Process Simulation, Pressure Relief Valve Sizing, and Flare System Analysis

An innovative work flow for performing overpressure protection analysis incorporating process simulation, pressure relief valve sizing, and flare system analysis

By  Wilfried Mofor, Aspen Technology Inc.;  Nicholas Brownrigg, Aspen Technology Inc.; Dinu Ajikutira Aspen Technology Inc. and Ron Beck, Aspen Technology Inc.

Relief valve sizing is a critical element of the early design of any process facility, both from the point of view of ensuring the feasibility of achieving a safe design but also to understand the capital cost scope for both the relief valves themselves and the associated relief system.

The design of the facility itself is usually performed by a process modeler, employing a simulation system such as Aspen HYSYS or equivalent.   Traditionally, the relief valve design has had to be performed in a stand-alone fashion, by an individual charged with that particular design task, employing a spreadsheet-type application that incorporates a particular organization’s safety and design rules.  Because a project cannot progress in the FEED workflow until the safety elements of the design have been verified, this is often a bottleneck in the process.  There are also specific examples (and most organizations can attest to them), where incorrect data was transferred from the process model to the relief sizing programs, leading to incorrect results, sometimes only discovered after the relief valve has been procured and possibly even installed.  Additionally, it is important for the safety engineer to rigorously consider all pressure source, routes, and failure potentials in enumerating the scenarios that need to be considered in the sizing analysis.   These are usually only able to be derived by examining the process flow schema in the process model (or P&ID).

An innovative solution to this design challenge has recently been introduced by AspenTech, involving integration of an accepted, tested and rigorous relief valve sizing program within the process model workflow. This workflow spans from the equipment source of the pressure through the relief devices into the flare network.  And additionally, from the process model, to the valve system design, to the overpressure relief network design and incorporating the documentation needed for the OSHA regulatory process and operator SOPs.

This paper will; (1)  describe the new overpressure protection analysis workflow that is enabled by this new technology solution, (2) report on a comparative analysis of a complex overpressure protection analysis design problem as executed with the traditional and new workflow, (3) and report on results to date in industry, both on the E&C and owner operator side, from application of this new workflow.  

We expect to be able to report on 3-4 industry case studies by the time this paper is presented, which we are currently in the process of gaining permission to present and to cite the names of the organizations involved.