Study On Leakage And Diffusion Law Of Storage Tank In Ammonia Refrigeration Room

Along with the rapid improvement of China’s economic strength,the national production and living standards of rapid progress,the chemical and food industries have also developed rapidly and become a popular industry.Most of the chemical and food enterprises use ammonia refrigeration system in their plants and set up ammonia storage tanks accordingly.After a long period of operation or improper operation,it is very easy to have tank leakage accidents,which will cause certain losses to the safety and health of the operators as well as the property of the enterprises.Therefore,many scholars have conducted a lot of experimental and research work on the diffusion process of gas leakage,mainly in the direction of numerical simulation and research on the prevention of ammonia leakage accidents and emergency measures.In this paper,for the ammonia leakage accident of storage tanks in the ammonia storage area in the refrigeration plant room,based on FLUENT software to establish the ammonia leakage dispersion model in the storage area,and study the laws of different leak port locations,different ambient wind speeds and leak port flow on the spatial location and concentration distribution of ammonia leakage gas clouds,the main work and conclusions are as follows.Collated the ammonia leakage events occurred in China in recent years,the current situation of safety and protection issues of ammonia refrigeration system at home and abroad,the current situation of research on gas leakage diffusion law,the causes and hazards of leakage occurring in ammonia refrigeration plant room,through the current experimental and simulation research on gas leakage process by domestic and foreign scholars,the specific variables studied in this paper are selected;ammonia diffusion model is established,the conditions required for numerical simulation,the ammonia storage tank in the refrigeration plant room Numerical calculation of ammonia leakage dispersion.By selecting different leak locations to set the tank leak,set different working conditions to simulate the ammonia diffusion,the analysis of simulation results,the following conclusions were obtained.1.When the leak location at the top of the tank,in the same leak location,the same leak flow,with the increase in ambient wind speed,high concentration threshold ammonia gas cloud is blown to a more distant range;in the same leak location,the same ambient wind speed,in the near tank location with the increase in leak flow high concentration ammonia gas cloud area first increases and then decreases,in the far tank location ammonia gas cloud area and concentration are with the increase in leak The area and concentration of ammonia gas cloud in the far tank location are reduced with the increase of leakage flow.2.When the leak location in the bottom of the tank,in the same leak location,the same leak flow,the leak along the X direction of ammonia concentration at each location with the increase in ambient wind speed,air transport to strengthen the role of ammonia gas cloud concentration and area are showing a trend of reduction,decrease;in the same leak location,the same ambient wind speed,the bottom of the leak location because in the upwind direction,the plane in which the Ammonia gas cloud diffusion is relatively good,and in the leak downwind to the right,if you increase the leak flow does not change the size of the ambient wind speed,the impact on the diffusion of leaking ammonia gas is relatively small.3.When the leak is located in the side of the tank,the leak and the wind direction on the same side or different side,in the same leak location,the same leak flow,when the greater the wind speed,the stronger the external force of air,downwind on the ammonia gas cloud diffusion distance,the greater the degree of dilution in the air,beyond the safety valve value of the concentration of ammonia gas clouds gathered to a lesser extent;in the same leak location,the same ambient wind speed,from the side view The ammonia gas cloud is circular in shape,and the larger the leakage flow,the larger the ammonia gas cloud accumulation area,which is not easy to spread.Based on the results of numerical simulation,according to different ammonia concentration on human safety and health as the standard,in order to ensure the required air quality,temperature and humidity in the ammonia refrigeration room,the premise should be set up in the roof above the room,surrounded by walls with multiple natural vents,set up at least two accident exhaust fans,one as the normal operation of the refrigeration system daily exhaust work,the other(or the rest of several)as a leak accident backup fans.Install ammonia leak alarms at appropriate locations and establish a reasonable protection system for the storage tank area.