Obtaining Approval of Alternative Vapor-Gas Dispersion Models

Editor’s Note: If you were hoping to skip something in this newsletter, this is probably it. It has words I haven’t seen since grad school.

The Department of Transportation/Pipeline Hazardous Materials Safety Administration (PHMSA) issued ADB-10-07 to owners and operators of LNG facilities. PHMSA has pre-approved the DEGADIS and FEM3A models to simulate thermal radiation and flammable vapor-gas dispersion around LNG facilities. This advisory explains several technical issues that must be addressed if an LNG facility operator requests to use an “alternative” vapor gas dispersion model for the LNG facility (other than DEGADIS and FEM3A). The issues include:

  • Source Geometry Handled by the Dispersion Model
  • Wind Field
  • Stratification
  • Terrain Types Available and Complex Effects: Terrain
  • Obstacle Types Available and Complex Effects: Obstacles
  • Turbulence Modeling (e.g., Algebraic, Favre- or Reynolds-Averaged Navier Stokes, Reynolds Stress Transport, Spalart-Allmaras One-Equation, K-Epsilon Two Equation, K-Omega Shear Stress Transport, Large Eddy Simulation, Detached Eddy Simulation, etc)
  • Boundary Conditions
  • Complex Effects: Aerosols
  • Computational Mesh
  • Discretization Methods
  • Sources of Model Uncertainty
  • Sensitivity to Input
  • Limits of Applicability
  • Evaluation Against MEP Quantitative Assessment Criteria

Didn’t I say you could skip this one?

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