Cross-border Risk Study Of Typical Atmospheric Pollutants In Sudden Accidents

In recent years, the sudden accidents are often occurred in the petrochemical, coal, pharmaceutical and other heavy chemical industries, for example, explosions, fire and toxic chemical emissions. The toxic and harmful gases spread with the wind which may cause long-distance pollution, even cross-border air pollution. The territory of China is vast and there are many administrative regions, with a number of other countries bordering on our country, so it is necessary to carry out research into cross-border pollution.The paper has filtered the substances which have potential risk to create the cross-border air pollution. Considering the physical properties and accidental type of the danger substances, liquid ammonia, liquefied chlorine and sulfureted hydrogen are selected as typical atmospheric pollutants. The leakage rate of the three pollutants is determined by the analysis of the source. The maximum allowable concentration of chlorine for short-term exposure and the maximum allowable concentration of harmful substances (for one-time exposure) in residential areas were selected as standards.The atmospheric diffusion process of liquid ammonia was simulated by risk software assuming that the cross-border distances are 5km, 10km, 15km and 20km. The atmospheric stability classes, the range of wind speeds and the time required for the pollution to reach a border were studied for source intensities ranging from 0 to 20kg/s.Cross-border air pollution from an instantaneous explosion and continuous leakage of liquefied chlorine and sulfureted hydrogen were investigated using the SLAB model. Typical weather conditions used were D stability with a wind speed of 3 m/s and F stability with a wind speed of 1.5 m/s. The results show that the relationship between the quantity of explosive or leakage rate and the spread of pollution and the relationship between the spread of pollution and the arrival time of pollution. This study provides a basis for early warning of and emergency response to cross-border pollution from the release of liquefied chlorine and sulfureted hydrogen.