Process Safety Study with Emergency Blowdown

  • Client:

    Major Oil Company
  • Field:

    Subsea / Topside Field

High-fidelity validation of emergency blowdown scenarios following API Std 521 relief contingency case emergency depressuring

In brief:

BPT investigated the flare system capacity during emergency blowdown scenarios.

The process safety study was performed with combined use of steady state & dynamic process simulator to fully utilize the installed flare system capacity with interlinked multiphase flow and dynamic process simulator.

API Std 521 relief contingency case emergency depressuring was followed.

The graph above shows the resulting blowdown rates as function of time for the "Fire Zone A" incident, that is; a confirmed fire in Zone A in a facility initiates a sequenced emergency blowdown of the entire facility. Process segments in Zone A is prioritized for depressuring first. Remaining process segments will be depressurized in a sequence not to exceed the capacity of the flare system.

Benefits and key findings:
  • Production chokes are sized based on maximum utilization of the safety barriers
  • Consistency between plant, report and prediction tools is taken care of
  • Detailed documentation of each relief scenario, including PSV utilization (in accordance with API Std 520) & flare rates, piping loads and PSD system response
  • Can effectively be performed from concept phase, since automated workflow for flare design & verification
  • Do it “right first time” to avoid unnecessary late modifications or even lost production
  • New tie-backs to existing facilities designed according to the integrity limits

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