| Liquid ammonia as refrigerant and chemical raw materials in the chemical industry has been widely used, the diffusion of ammonia due to the leakage of ammonia can easily cause a fire, explosion, poisoning and other accidents, and cause a serious threat to the field staff and property. Many liquid ammonia tanks are disposed in an unopened space, and ammonia accumulates easily reaching very high concentrations in the space. If emergency measures are not taken immediately, it may cause a greater loss than the outdoor liquid ammonia spill.Therefore, the study of liquid ammonia leakage diffusion rule in unopened space and of emergency measures have important significance.In this dissertation, features of liquid ammonia leakage diffusion, absorbed by different water sprinkler distribution under ventilation are simulated and analyzed. Taking a refrigeration station as an example, ICEM software and FLUENT software are used to simulate the liquid ammonia leakage under ventilation conditions, ammonia leakage velocity and concentration fields are analyzed over time. As a result, the liquid ammonia leakage diffusion rules are summarized. Ammonia absorption model is established, and the nozzle model is selected. Under ventilation condition, three kinds of partial spray and full spray are studied by numerical simulation of the ammonia concentration in unopened space. The IDLH area, PC-STEL region, explosive areas and low temperature zone over time are analyzed after the leakage of ammonia in the unopened space.By comparing experimental results,it shows that partial spray can effectively slow down trend diffusion of ammonia hazardous areas and tends to spread to the roof space after ammonia leaking. Compared with partial spray, full spray can better reduce IDLH breathing area in staff average height, it can reduce the concentration to a safe level part of the region in a short time for staff to evacuate provides a good conditions of time and space. |
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