Model of forced deposition of heavy dangerous gases

A model of diffusion spreading in the atmosphere of dangerous chemicals with a density greater than atmospheric air is developed. The model was created by solving the Navier-Stokes equations with appropriate boundary conditions. The peculiarity of the obtained model is the consideration of the process of forced deposition of gas by a finely dispersed liquid flow of different intensity during gas propagation. In this case, deposition occurs due to the processes of gas sorption by liquid droplets. It is established that the propagation of heavy gases in the atmosphere shows signs of fluid flow, and the resulting model is a transitional option between systems of gas diffusion models and hydrodynamic models of fluid flow. Taking into account the assumption of gas incompressibility due to the significant difference in sound speeds between the gas under study and air allowed us to obtain a simplified view of the transient regime. The modelling results for chlorine emissions from a point source showed that the effect of wind speed is much smaller compared to ammonia, which increases the importance of the contribution of the diffusion process. The resulting model allows predicting the size of the chemical damage zone in the event of accidents involving the release of heavy gases with their active deposition by stationary and mobile sprayers. In practice, water curtains at the technological openings of heavy gas storage and operation facilities can be considered as stationary sprayers. The work of rescue units at the incident site can be considered as mobile sprayers. Refinement of the results of forecasting the consequences of emergencies involving the release of hazardous gases will improve the accuracy of the design of the safety system at such facilities and help in making effective management decisions in the elimination of emergencies of this nature.