Study On Numerical Simulation Of Ammonia Leakage And Dispersion Process

Accelerating the process of industrialization, and ammonia as raw material for industrial production or final product, appeared more and more in the public eye, but due to management errors, employee misuse, as well as external force majeure factors, could cause ammonia leakage and diffusion. Under normal conditions, ammonia gas is flammable, explosive, toxic and other dangerous properties, the consequences of a problem there are potentially more severe.In order to verify the correctness of the numerical simulation. Based on FLUENT CFD software platform, the establishment of three-dimensional numerical model of gas- leakage diffusion, analyzed diffusion of CO2. Comparison of experimental data with simulation results, the instantaneous concentration distribution is good agreement with the experimental results. Studied direction of wind speed, location, leaks and other factors impact on leakage and dispersion process. Wind effect on the leaking gas has a dilution and transport, under the action of wind, gas diffusion to Leeward, as wind speed increases, the gas density decreases risk of decrease. As wind speed increases, the leakage of gas diffusion in a horizontal direction regional influence will be weakened. A leak in the vertical direction, under the action of gravity, gas deposition to the ground, larger gas concentration near the ground, and leaks in the horizontal directio n, gas distribution is more uniform, and smaller gas concentrations on a vertical surface leakage risk high when compared to the leak in the horizontal direction.Actual production places of meteorological conditions and ammonia storage tank layout of situation, simulation has ammonia leak diffusion of process, draws different moments ammonia of concentration regional figure, estimates different conditions, gas leak of effects range, simulation results displayed, in static wind conditions, storage tank occurred small hole leak, leak speed is big, leak gas will along jet flow direction quickly spray out, and to shot streamlines for symmetry, uniform to around diffusion, gradually full whole regional. When leak direction and wind is identical, prevailed to regional of gas concentration high, belongs to belongs to heavy degrees against regional. When leaking vertical direction of wind, alert district should set in storage tank Southeast azimuth Shang, distance leak mouth 30 m of range within is high concentration danger zone, belongs to heavy degrees against regional, in wind 80-120 m of regional range within, with and leak mouth distance of reduced, gas of concentration has reduced, is in the degrees danger zone. When leakage direction and direction are the same, the downwind area 80-120 m, which belongs to the moderate risk area. In calm wind conditions, is not conducive to the proliferation of dangerous gases, hazardous gas diffusion region larger, prevention should be strengthened. Plant construction should be selected at the annual minimum frequency of wind direction the upwind side, plant layout less risky areas should be set up in high risk areas of the upwind side, the source of the leak should be constructed in buildings such as offices, staff quarters and a control room of the perennially dominant wind direction, the downwind side, while the downwind side to avoid possible ignition source.ICI Mond plant risk analysis on ammonia tank area, before come to the factory to take compensatory measures unit of the toxicity index is "high", the main index of toxicity "enormous" explosion indicator is "high", gas indicator is "medium" all risk "medium" ammonia storage tank area and the inherent high risk of explosion and poisoning. Adopt compensatory measures, the explosion indicator dropped from high to low, all the risk score from medium down to moderation. Evaluation units of all risk indicators in a State of ease, but accidents, cell toxicity index, gas explosion index is higher, you still need to take effective measures, and to develop a comprehensive emergency plan, reduce the risk coefficient of each link, thus reducing the toxicity of evaluation units and gas explosion indicator, reduce damage and loss caused by the accident.According to the nature of the various types of disaster events, severity and controllability and sphere of influence factors such as sudden disasters and accidents are divided into four classes: class I(extremely large), secondary(major), the grade III(large), and IV(General). The four p hases of emergency management: prevention, preparedness, response and recovery phases, and draw up appropriate emergency measures to guide the emergency work after the accident, in order to improve business advise on the level of hazardous chemical accident emergency rescue.