Problems in granulating compound fertilizers

It is mainly a matter of the formula, that is, the source of the raw materials used. For nitrogen, for example, there are ammonium chloride, urea, ammonium sulfate, liquid ammonia, **, monoammonium phosphate, diammonium phosphate, etc. The way in which these substances form molten compounds during the mixing and granulation process varies, and this in turn determines the quality of the final product.

I’m truly sorry as I don’t have the relevant information with me; I will definitely provide more details once I have the chance.

1. It is related to the types of raw materials used in the formula as well as the nutrients contained in them. 2. Operationally, it is related to the granulation temperature and the drying temperature. 3. It is also related to the temperature during packaging and the height at which the finished product bags are stacked. Our factory originally used acid-ammonia for granulation, but switched to using urine for granulation; in both cases, the strength of the products remained satisfactory.

I think it might be that: if the spray granulation process is used, the temperature of the granulator is too low, its speed is too slow, and the moisture content of the material is too high, resulting in uneven particle shapes； The temperature of the hot air in the dryer is too low, resulting in insufficient particle strength and making them fragile. If the melt granulation process is used, it is consistent with what is described on the second floor

I have a different view on the sixth floor; there are three ways in which granulation occurs in the spray granulation process: coating granulation, bonding granulation, and self-granulation. In addition to irregular particles resulting from the mechanical crushing of large pieces of material. Coating to form granules involves good atomization of the slurry, with particles growing into granules by being wrapped layer by layer from the inside out, resulting in the best particle quality. Granulation occurs due to poor atomization of the slurry, causing the particles to stick together and form granules. Self-granulation refers to particles formed as a result of excessive atomization of the slurry. In the production of monoammonium phosphate, the particle strength is almost independent of the inlet and outlet gas temperatures. In the production of compound fertilizers, heat-sensitive materials are subject to restrictions: if the inlet temperature is too high, the materials melt into lumps and cannot be granulated; if the temperature is too low, drying does not occur and excess moisture cannot be removed, thus limiting the production capacity of the facility. Therefore, raw material matching is the key to the spray granulation of compound fertilizers.

Well said, but there are some points that aren’t entirely accurate. The statement that \"the intake air temperature is too low and cannot be dried enough, preventing the removal of excess moisture and thus limiting the production capacity of the device\" is questionable. From a heat transfer perspective, the ability to remove heat does not depend solely on the temperature of the hot air; it also depends on the volume and speed of the airflow. When the airflow volume is high and the speed is fast, it is possible to lower the intake air temperature appropriately. This is exactly what our company does – the temperature at our equipment’s inlet has ranged from 400–500 degrees, down to over 300 degrees, and now it’s around 200 degrees, yet production remains stable (for the granulation of compound fertilizers). With a lower temperature, ammonia loss is relatively reduced. . . . . . . . . . . . This post was last edited by bht11 on 2007-5-25 10:21]

The original poster is right: “The intake air temperature is too low and cannot be dried, so excess moisture cannot be removed, which limits the production capacity of the device.” Replacing “limits the production capacity of the device” with “results in low thermal utilization by the system” is more accurate. What the original poster mentioned might refer to the production of compound fertilizers. When producing compound fertilizers, due to the properties of the materials used, it is necessary to use high air flow rates and low temperatures; otherwise, the materials will melt and decompose, which not only results in products with substandard nutrient content but also leads to increased consumption, such as ammonia loss. The situation is exactly the opposite in the production of monoammonium phosphate: it is desirable to increase the temperature of the air entering the machine, and as long as the exhaust gas does not condense, the temperature of the air exiting the machine should be reduced as much as possible. This improves heat utilization and the production capacity per unit volume of the drying system, thereby enhancing production efficiency. This post was last edited by zengdonghai on 2007-5-25 11:51.]

For the granulation of compound fertilizers or monoammonium phosphate, there are not only material balance and heat balance, but also particle balance. If any one of the three balances is disrupted, production cannot proceed normally. Regarding the decreasing temperature inside the machine mentioned by the original poster, it’s possible that the material-related issues associated with the compound fertilizer granulation material were not taken into account during the design phase. To maintain production, high air volumes are required, which increases the energy consumption per unit of product and significantly raises the load on the exhaust dust removal system. Answer #7 is in the context of comparing the production of two or more products using the same set of equipment.

Could you be more detailed? It’s hard to draw a conclusion like this