gFLARE: PSE's Oil & Gas technology

PSE is the recognised industry-leading provider of high accuracy analysis for blowdown, pressure relief and flare system design. Our proprietary gFLARE® modelling software is at the heart of our expert analysis service. It enables a significantly more accurate quantification of risk than conventional engineering screening methodologies. gFLARE provides a single fully integrated technical solution for modelling scenarios such as…

  • Process equipment and piping during depressurisation (“blowdown”) and pressurisation
  • Process equipment and piping during pressure relief scenarios (such as blocked outlets)
  • Transient flare system behaviour
  • Fire attack and time to rupture

gFLARE is compliant with the latest edition of the industry standard API 521 guidelines for pressure relief and depressuring systems and has been extensively validated against pilot and full facility data.

The gFLARE difference

Conventional design techniques use many simplifying assumptions: dynamic flare system events are treated as steady-state; complex process blowdown systems involving multiple pipe segments and vessels are lumped into pseudo-vessels; the controlling, non-equilibrium thermodynamics are neglected. All of these assumptions give rise to incorrect results. At best, they are conservative, leading to over-design and unnecessary CAPEX. In many cases, however, results are non-conservative, giving rise to a real danger of failure.

Dynamic flare system analysis

Pressure-relieving and depressuring events are inherently transient, yet conventional flare network design techniques use constant peak relief flows in steady-state simulations to assess system capacities and to determine back-pressures downstream of valves, flare metal temperatures, Mach number in the headers and radiation at the flare tip. gFLARE enables full assessment of the transient behaviour of the flare system, yielding both a highly accurate prediction of system capacity and a precise view of cold front propagation into the flare system.

Distributed blowdown models

Every vessel or valve in a blowdown segment experiences different conditions, but conventional approaches crudely lump them together in a single pseudo-vessel representation. gFLARE’s distributed models represent each pipe and equipment item within the blowdown segment explicitly. This allows the analysis to calculate accurate metal temperatures, identify specific locations of concern and test mitigation strategies.

Rigorous thermodynamics

Depressurisation is fast. There is no time for vapour and liquid phases to reach equilibrium, but conventional practices assume just that. gFLARE’s rigorous, rate-based thermodynamics predict accurate temperatures even when liquid condensation occurs.

Detailed fluid / metal heat transfer

Materials of construction decisions demand accurate metal temperatures. For Oil & Gas facilities, the minimum metal temperature is generally observed in the process equipment during the pressurisation or depressurisation. Blowdown segments may contain large diameter vessels, large and thin bore pipes and heat exchangers – these all have different heat characteristics, heat transfer areas and metal mass. gFLARE’s detailed heat transfer models give engineers clarity with precise information on locations of low temperatures to guide costly metallurgy decisions.

Validated in the real world

gFLARE is extensively validated against published experimental data as well as data for the blowdown of full scale Oil & Gas facilities. gFLARE is an approved technology for more than 15 operating companies including four super-majors and multiple large national oil companies.

Integrates with your workflow

gFLARE has been developed so that existing models from conventional analysis tools can be quickly replicated in gFLARE architecture, ensuring analysis occurs in a timely fashion. Existing steady-state flare system models can be imported directly into gFLARE.

Coupled process and flare

For a blowdown operation, common practice first requires that separate depressurisation calculations are performed for each blowdown segment and then the results are used as an input for the steady-state flare calculations. This method largely ignores flare back-pressure controllers, sequenced blowdown processes and low pressure sources. gFLARE’s fully coupled process and flare models incorporate all of these effects with a realistic representation.

Hybrid modelling with CFD

Sometimes in order to perform complex analysis, it is necessary to combine the best available technologies. In separator cold spot analysis, complex flow patterns are best done in CFD while the transient system behaviour and non-equilibrium thermodynamics are best modelled in gFLARE. PSE’s hybrid modelling interfaces – in collaboration with industry leaders such as ANSYS FLUENT – are designed for just this type of analysis.