Effective Emergency Relief System (ERS) design helps companies meet risk-management goals, compliance requirements, and sound business practices. ioMosaic provides a total ERS solution with our comprehensive ERS design services, from reactivity testing for design basis determination to calculations for Z-axis deflection from dynamic loads.
Our team has decades of experience performing PRFS analysis and design.
Our risk-based approach helps mitigate near-unventable scenarios to a tolerable level of risk.
Better evaluate hazards in your facility with an accurate process simulation.
Delivering properly designed pressure relief systems that save both money and time.
Reasonable estimates of the expected time to failure (ettf) or expected time to yield (etty) are required and necessary for effective risk management as well as effective emergency and fire protection and response. Read this paper for a demonstration of calculating ettf or etty in fire exposure scenarios with Process Safety Office® SuperChems™.
Two-phase flow is often considered in system hydraulics as well as the evaluation and design of pressure relief and effluent handling systems. A variety of scenarios can lead to two-phase flow under relief conditions. In general, two-phase flow during relief can occur because of flow hydrodynamics and poor vapor/ liquid disengagement where (a) the liquid swells due to generation of vapor bubbles in the liquid 1, (b) fluid expansion occurs due to heating, and/or (c) the superficial vapor velocity is high enough through the pressure relief device. Oversized relief devices can induce two-phase flow because a large relief flow area yields a higher superficial vapor velocity. Runaway chemical reactions and/or chemical systems that are viscous and/or foamy almost always lead to homogeneous two-phase flow. Two-phase flow can also occur by entrainment, for example, where gas is sparged at a high enough rate in the liquid. In some systems, condensation leading to two-phase flow in the discharge piping can also occur due to expansion cooling caused by pressure reduction through a control valve or a pressure relief device. Numerous two-phase flow models have appeared in the literature. These models represent broad ranges of theory. Some are based on single-phase critical flow, others on homogeneous equilibrium flow, frozen flow, separated flow, slip flow, and/or non-equilibrium flow. Homogeneous equilibrium flow models assume equal vapor and liquid velocities and calculate the change of quality with pressure using an isenthalpic or isentropic thermodynamic path. Homogeneous frozen models assume equal vapor and liquid flow velocities and that the quality is frozen along the flow path, i.e., no change with respect to pressure or temperature. The separated flow models assume different vapor and liquid flow velocities and account for mass, momentum and heat transfer between the separate phases.
This PSE module performs efficient tracking of process safety related data and analysis. A customized workflow allows for a specific operating unit or the entire facility to be studied and evaluated for compliance.
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.
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Nov 3, 2023