Problems and improvement measures in compound fertilizer granulation


The chemical plant's annual output of 150,000 tons of NPK fertilizer manufacturing process adopts drum granulation technology, in which the granulation process is an important and key process, which directly determines the stability of the system operation and the quality of the product. The following is an analysis of the problems and improvement measures in the granulation of compound fertilizer equipment.

1. Pilling:(1) Main phenomenon: particles larger than 4mm appear.
(2) Reason analysis: The granulator of compound fertilizer equipment has improper ratio of solid and liquid, the spraying amount of washing liquid and steam is large, the temperature of the material in the granulator is low, the raw material is too damp, the speed of the granulator is slow, and the urine The concentration of the liquid is low, the finished product is not produced in time to continue to circulate, and the dosage is too much, resulting in high water content of the material.
(3) Improvement measures: firstly reduce the spray amount of washing liquid or steam, and secondly increase the concentration of urine, the speed of the granulator, the hot air temperature of the hot blast stove, and increase the air volume of the fluidized bed.

2. High-temperature dry powder:
(1) Main phenomenon: A white, shiny powder with a temperature greater than 60°C appears in the system.
(2) Reason analysis: the amount of returned material is large, the speed of the drum granulation machine of the compound fertilizer equipment is too fast, the dosage is small, the spraying amount of steam and washing liquid is insufficient, and the gap between the crushers is small.
(3) Improvement measures: increase the spraying amount of washing liquid and steam, adjust the speed of the granulator to 89 rpm, and reduce the temperature of the hot blast stove or the concentration of urine if necessary.

3. High temperature wet powder:
(1) Main phenomenon: A kind of powdery material with very low particle rate, wet and yellowish appears in the system.
(2) Reason analysis: The main reason is that the granulation temperature is far higher than the normal required temperature, so that part of the salt in the raw material or molten and a large amount of washing liquid with a lower temperature is used, which makes the molten salt instantaneously cool and embrittle It becomes a loose powder.
(3) Improvement measures: mainly reduce the amount of steam.

4. Low temperature wet powder:
(1) Main phenomenon: A dark and black powder appears in the system, and the temperature is lower than 33°C.
(2) Reason analysis: The compound fertilizer manufacturing equipment system has fewer rystal nuclei, low granulation temperature, and poor viscosity of additives.
(3) Improvement measures: increase the ventilation door beside the raw material belt to make the air flow smoothly, the system circulates the crystal nucleus or the system directly adds the crystal nucleus to increase the temperature of the hot blast stove and increase the concentration of urine.