Treatment method for water generated during reduction in the temperature-raising reduction of synthetic catalysts

There are many posts on the forum regarding reduction using synthetic catalysts; LZ can search more to take a look. By \"treatment at the time of water release,\" you are probably referring to ways to prevent freezing, right? Your approach is correct – by adding ammonia in advance, the freezing point is lowered, and this also reduces the water vapor pressure in the gas phase, which helps to decrease the water vapor concentration.

Is it feasible for our plant to inject ammonia into the ammonia separator before raising the temperature? Answer: It’s completely feasible; that’s exactly what we do! The reason is as LS said.

1. Strictly control the low-temperature ammonia vessel to prevent liquid level buildup! ! ! . It is best to shut off each level control valve completely. 2. Once heating begins, ammonia can be injected to prevent freezing; if the entire catalyst bed is replaced, ammonia must be added. 3. The low-concentration ammonia solution from the initial stage can be directly recycled into urea, or sent to an ammonia treatment facility for processing to produce a solution of the appropriate concentration for sale; otherwise, it can be stored in a large tank! Strictly exclude it from the area – it pollutes the environment! 4. Generally speaking, as long as the ammonia concentration at the outlet of the synthesis tower is close to 3%, the liquid ammonia can also be sent directly to the ammonia tank! , but be careful of the ammonia tank pressure, as it contains water!

1. Since the water generated during the reduction of the catalyst tends to freeze and block the tubes of the ammonia cooler, once the system has been pressurized and purged successfully and is ready for operation, ammonia can be added to the ammonia separator or heat exchanger, as ammonia water has a low freezing point. 2. The ammonia produced in the early stage of reduction can be discharged to the urea hydrolysis system; when the ammonia content at the outlet of the tower is above 5%, it can be discharged to the liquid ammonia storage tank.

For this question, you can refer to the following post (click to enter): Why is liquid ammonia injected during the initial heating and reduction stage of the synthesis tower? Problems related to ammonia charging at the initial stage of operation in the ammonia synthesis system. As for the uses of dilute ammonia water, they vary from plant to plant; we send it to the gas station for concentration. Once the ammonia concentration reaches 80%, it is sent to the liquid ammonia storage tank.

It depends on the process of your ammonia synthesis system. If the temperature of the ammonia cooling medium can be well controlled, and kept above 5 degrees Celsius (with an ammonia gas pressure of 0.4 MPa) until the ammonia concentration in the dilute ammonia solution falls below 30%, then the ammonia cooler will not freeze. And you inject liquid ammonia before restoration; this is the method generally used in the traditional ammonia synthesis process. The purpose is to prevent the recovered water from freezing in the ammonia cooler and blocking the pipes!

We used to inject liquid ammonia, but it was difficult to control the amount; later we switched to pouring ammonia from the storage tank as vent gas (gaseous ammonia). Whether it is gaseous ammonia or liquid ammonia, it is sufficient to control the NH3 concentration in the synthesis cycle gas at ≥3%, and the effect will be the same. Furthermore, if there is an ammonia vaporization unit, it is better to recover ammonia from the reduced water in the later stages.

The physical water from the first stage of longevity production contains virtually no ammonia and can be discharged on-site. Ammonia water with an ammonia content of less than 25% can be recovered most effectively; otherwise, it should be diluted with water and discharged. As the reaction proceeds and the ammonia concentration exceeds 25%, it is sent to a medium-pressure storage tank for storage.