Gravity Spreading and Turbulent Dispersion of Pressurized Releases Containing Aerosols

Summary

Sudden release of a pressurized chemical results in instantaneous flashing of fraction of the chemical into vapor. If the pressure inside the tank or a pipeline falls very rapidly, much of the liquid fraction may be thrown into the vapor cloud as a result of vigorous boiling process. A gravity spreading and a turbulent dispersion model has been developed to determine the dispersion hazards of pressurized releases containing liquid aerosols. The gravity spreading model determines the initial lateral spreading of the vapor cloud. A thermodynamic equilibrium model is used to determine the evaporation of liquid aerosols, the mean density and temperature of the cloud. Finally, when the effects of gravity are small, the transition from the gravity spreading model to a turbulent diffusion model takes place. Results are presented for pressurized propane releases at various exit velocities and different initial aerosol mass fraction.