Study On Ammonia Leakage And Dispersion In Liquid Ammonia Refrigeration System Specific Space

Ammonia has been widely used in chemical industry and food industry.More and more accidents of ammonia leakage and dispersion occurred in recent years.The dispersion laws of ammonia under different meteorological and source conditions are different and complex,yet few comprehensive studies on the characteristics of ammonia dispersion were carried out at present.In this paper,we designed a small scale experiment and numerical simulation method to study the leakage and dispersion of ammonia in a specific space.Based on the investigation of the layout in a food factory,a series of experiments have been designed to study the characteristics of ammonia dispersion concentration distribution under different conditions.The small scale numerical model is established to determine the turbulence model used in numerical simulation.Then the law of ammonia dispersion was studied by numerical simulation and the accident consequence have been studied.The results of wind tunnel experiments showed that the concentration of ammonia was mainly concentrated on the central axis.The maximum concentration can be reached at the height of 3cm and at 0.8 ~ 1.2 m/s.The concentration of each point is directly proportional to the release rate and the concentration near source release is much higher than the concentration away from the source.The RNG simulation results are very close to the experimental results.When the ammonia gas moves to the top of the obstacle,the concentration decreases significantly.And the concentration range becomes wider after passing the obstacles.The source of the plant and the windward side of the plant are the high-speed zone and the obstacle area is the low velocity zone.The variation of concentration in the obstacle region is the largest with temperature.For the study on accident consequence,the hazard concentration range covers all areas from the release source to the obstacles and the lethal concentration zone and the combustion zone are only near the source.The results of this study provide a reference for the prediction of the leakage accident of liquid ammonia refrigeration system in the food industry.