What is ammonia escape? Why does ammonia escape?

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Ammonia escape refers to the phenomenon in ammonia-containing industrial processes where ammonia fails to participate in reactions as intended or to be effectively captured, instead leaking from the system and being released into the environment. Specifically, the main reasons for ammonia leakage include the following aspects: Firstly, the use of ammonia spray guns is an important source of ammonia leakage. The ammonia spraying rate of each ammonia spray gun may be unevenly distributed, resulting in locally high or low concentrations of ammonia in the flue gas. Furthermore, if the flow rate of the flue gas is uneven, it will also affect the distribution of ammonia, resulting in excessively high ammonia concentrations in certain areas and increasing the likelihood of ammonia leakage. Especially at the nozzle exit, due to differences in the ammonia injection amount, ammonia escape is more likely to occur in areas with higher concentrations. Secondly, reaction temperature is one of the key factors affecting ammonia escape. When the reaction temperature is too low, the reaction rate between NOx and ammonia decreases, which causes a large amount of NH3 to escape without participating in the reaction. On the contrary, if the reaction temperature is too high, ammonia may react with other substances to produce unwanted by-products such as NO, which also increases the risk of ammonia escape. Therefore, maintaining the reaction temperature within an appropriate range is an important means of reducing ammonia escape. Furthermore, the condition of the catalyst also affects ammonia escape. Catalyst clogging and aging lead to a decrease in denitration efficiency; to keep environmental parameters within acceptable levels, it is necessary to increase the amount of ammonia injected. However, this often creates a vicious cycle: the clogging and aging of the catalyst require more ammonia to participate in the reaction, and more ammonia can in turn exacerbate the clogging and aging of the catalyst, leading to more ammonia escaping. The amount of misting air flow also affects ammonia escape. If the atomization air volume is too low, the atomization effect of the spray gun will be poor, resulting in insufficient mixing between ammonia water and flue gas. This inadequate mixing prevents some of the ammonia solution from participating in the reaction, resulting in ammonia escape. Finally, the concentration of ammonia solution is also an important factor affecting ammonia escape. If the ammonia concentration is not set properly, either too high or too low a concentration can lead to ammonia leakage. Excessively high concentrations may cause the ammonia solution to shut off automatically during spraying, resulting in poor atomization and increased ammonia leakage ； On the other hand, too low a concentration may require more ammonia to achieve the desired denitration effect, which in turn increases the risk of ammonia escape. Ammonia escape not only pollutes the environment but can also pose risks to human health. Prolonged exposure to ammonia gas can cause damage to areas such as the conjunctiva of the eyes, nasal mucosa, lungs, and skin, leading to inflammation and ulcers, and even chronic conditions. Therefore, monitoring and controlling ammonia emissions is crucial; a range of measures must be taken to reduce such emissions in order to protect the environment and human health.