Formular for npk fertilizer production

From a technical point of view, the important factor in the formulation design of extrusion granulation products in NPK fertilizer production line is the characteristics of materials. Next, we discuss another aspect of the influencing factors, that is, the influence of the type of raw materials on the formula.

1. Material compatibility

Theoretically, any proportion of NP or K base fertilizer can be prepared, and trace elements and even pesticides should be added if necessary. However, materials must be limited by compatibility. The substances in the formula shall not have chemical reaction in the process of fertilizer manufacturing, and occasional reaction shall not be allowed.

2. Effect of urea on formula

The international fertilizer center has done a lot of experiments on the effect of urea on the performance of compound fertilizer, although the report does not mention the same example as the product formula we are studying, and most experiments do not carry out granulation on extrusion. Yes, but its conclusion is still useful to us.

NPK Drum Granulation Line
NPK Drum Granulation Line

Because urea absorbs moisture easily, the critical relative humidity of NPK compound fertilizer decreases significantly. At the same time, the international fertilizer center also found that this effect is more serious when potassium chloride is used as the potassium source of compound fertilizer.

Due to the low critical relative humidity, urea based compound fertilizer is easy to absorb water, which blocks the screen, pipeline, chute, etc.
When the temperature increases, the critical relative humidity of urea based compound decreases rapidly.

The production capacity of the dryer must be determined by many factors. Some urea based NPK fertilizers begin to soften at 70 ℃. If the outlet temperature of the dryer is higher than this temperature, the fertilizer particles will be too soft, the granulation process will be out of control (the particles are too large), and the internal scabs will form. Drying causes difficulties in screening and transportation.

In the same report, the international fertilizer center also tested other aspects of urea, such as water absorption, moisture permeability, water holding capacity, particle integrity, fluidity and agglomeration. The result is negative, which will have an adverse effect.

In short, the formula design test and production of extrusion granulation products in compound fertilizer production line show that the use of urea in compound fertilizer will encounter great trouble, not only because it affects the storage and transportation performance of products, but also because it also has a certain impact on the production process.

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How to dry compound fertilizer granules?

Drying process is also the key of NPK fertilizer production line. The fertilizer should be dried after granulation to reduce the moisture in the particles and increase the hardness of the particles, which is very important to the quality of the fertilizer.

1. The installed dryer shall be subject to an empty machine test for not less than 4 hours. In case of any abnormality during commissioning, it shall be handled in time.

Rotary Drum Dryer Used in Fertilizer Production Line
Rotary Drum Dryer Used in Fertilizer Production Line

2. After commissioning, retighten all connecting bolts, check and supplement lubricating oil. After the test is normal, the load test can be carried out.

3. Before load test run, single air test run shall be conducted for each auxiliary machine. After the single machine test is successful, transfer to the joint test.

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4. Ignite the hot air oven to preheat the dryer and start the dryer at the same time. Do not rotate the cylinder to prevent the cylinder from bending.

5. According to the preheating condition, the wet material is gradually added into the drying cylinder, and the feeding amount is gradually increased according to the moisture content of the discharged material.

6. The preheating of the dryer needs a process, and the hot blast stove should also have a preheating process. Sudden fire is prohibited. Prevent local overheating and uneven thermal expansion and damage.

7. Fuel combustion value, thermal insulation quality of each part, moisture content of wet material and uniformity of feeding amount affect dry product quality and fuel consumption. Therefore, it is an effective way to improve economic benefits to make each part reach the state as much as possible.

8. In the working state, the roller frame shall be filled with cooling water.

9. All lubricating parts shall be filled in time.

10. During shutdown, the hot blast stove shall be closed first, and the drying cylinder shall continue to rotate until it is cooled to close to the outside temperature.

11. It is forbidden to stop at high temperature to prevent the cylinder from bending and deformation.

12. In case of sudden power failure, close the hot blast stove immediately, stop feeding, and turn the cylinder half a circle every 15 minutes until the cylinder cools down.

The operating procedures of this fertilizer manufacturing process should be careful and professional. Failure to follow this procedure will cause the cylinder to bend.