The paper deals with an emergency and modeling the spread of gasoline vapor in the environment. The solution of the problem is realized on the example of gasoline hydrotreating unit L-24-300 refinery.

Analysis of emergency incidents in the field of oil refining in Russia and abroad showed that the most dangerous situation is the formation of explosive cloud (90% of all accidents). The consequences of fire or explosion at the location of technological equipment in the outdoor performance are of the global character.

The units and equipment are ranged on the main indicators – the number of accesses of the dangerous substance, its pressure and temperature. To calculate the complex rank R according to the statistics of operation of oil refining equipment weight factors to determine the contribution of each indicator into an integrated rank were assessed. Besides operating indicators the residual value of the equipment, which will determine the direct damage in the event of fire or explosion, was taken into account.

Modelling of gasoline vapors dispersion was accomplished by UPRZA “Ecolog” program. The dissipate maps are built for the least favorable summer conditions for 4 wind speed variants: of 0,5 m / s to 10 m / s. A three-dimensional model for calculating a level of air pollution was built with the help of asymptotic transformations. A method of coordinate transformation into the asymptotic variable is shown. Simulation performed for settlements in the western and eastern areas with the highest-density related technological production plants.