Various factors affecting the efficiency of the granulator

It is understood that many feed mills have failed to meet the expected design requirements due to the process arrangement and operation technology of the pellet machine, and the particle surface is not smooth, the hardness is low, the crushing is easy, and the powder content is high. The main reasons that affect the production efficiency of the granulator during the granulation process are as follows:

Raw material factor

The raw material factors directly affect the effect of granulation. The materials with higher starch content are easily gelatinized by steam. After quenching and tempering, these raw materials have certain viscosity and are favorable for pellet formation. For raw materials with high crude fiber content, a certain amount of oil is added, and the friction between the material and the ring mold can be reduced during granulation, which is beneficial to the material passing through the ring mold, and the appearance of the particles is smooth after forming. Generally, the added amount is about 1%, and the added amount is too high, which is easy to cause the particles to be loose. If more fats and oils need to be added, it can be considered to be sprayed after granulation, and is particularly suitable for producing high-energy feed. The particle size of the crushed raw material determines the surface area of ​​the feed composition. The finer the particle size, the larger the surface area, and the faster the moisture absorbed by the material in the steam, which is beneficial to the quenching and tempering of the material. From the granulation point of view, the pulverization is fine, the granulation strength is high, but the steam is added more, and the squeezing is too small, and the pulverization power consumption is too high. The particle size is too coarse, the ring mold and the pressure roller are increased, and the granulation forming is difficult, especially the formation of the small-aperture ring mold is more difficult, and the material gelatinization effect is poor, resulting in high material consumption, low yield, and high particle powder content. Therefore, the production of livestock and poultry feed is usually carried out. The crushed corn should adopt a sieve plate of 2.5 to 3.0 mm, which can avoid the disadvantages of excessive particle size, and ensure the particle size required for sufficient conditioning of the feed, which is beneficial to reducing the powder content of the particles. In addition, it is necessary to pay attention to the mixing uniformity before granulation, because the composition of the feed formula is complex, and the specific gravity of various raw materials varies greatly. For different formulas and different varieties, different mixing times are used, so that the variation coefficient of mixing uniformity reaches about 5%. The post-granulation process lays a good foundation.

2. Feed flow control

In order to make the granulator work at full load without interruption, the material flow entering the granulator must meet the granulation needs, and the feed structure should effectively eliminate the intermittent phenomenon of the feed due to agglomeration. Taking the SZLH40 granulator as an example, the material flow rate should not be less than 10T/H. It is necessary to adjust the flow stability of the feeder in actual production. It is more reasonable to install a buffer tank directly above the granulator, if not set The buffer tank, or the longer connection between the buffer tank and the feedstock (0.5m or more), it is difficult to ensure a stable feed amount. Many feed mills are busy looking for the reasons in the granulator itself when the granulator production efficiency is not normal, and neglect the incoming factors. In fact, many times the decline in production efficiency is caused by the unstable flow of incoming materials. Generally speaking, when the granulator runs smoothly and normally, the steam supply is sufficient, the feed gate is fully opened, the feed speed is adjusted to the rated value, and the main motor work never reaches the rated electric value, it can be judged that the incoming flow is insufficient. At this time, the cause should be identified and the treatment should be treated.

3. Steam quality control

The use of steam granulation can effectively increase the yield of the granulator and improve the quality of the granules. Steam is the source of moisture addition during quenching and tempering, and is the heat source for the gelatinization of feed starch. Adding a certain amount of steam in the quenching and tempering can kill a part of the bacteria in the feed, and can dilute the natural binder in the feed, so that a thin aquifer is formed outside each particle in the material, which is beneficial to the gelatinization of the material. It facilitates granulation and improves the quality of pelleted feed. The correct steam piping design is to ensure steam pressure and flow, and to effectively prevent condensate from entering the regulator. The steam drum should be as close as possible to the granulator to improve steam quality, because steam quality is critical to the granulator, and steam of insufficient purity will cause the granulator to clog or produce undesirable feed and is prone to a series of failures. The suitable saturated steam pressure should be 0.2-0.4Mpa. When the pressure is too low, the quenching and tempering index can not be achieved in the fixed quenching and tempering time; when the pressure is too high, the steam temperature is also high, and the steam passes through the conditioner to heat the material. The temperature is enhanced, which is easy to cause high material temperature, low moisture, localized material burning, etc., which affects the quality of granulation. To ensure that the steam pressure is always stable, the pressure fluctuation should generally not exceed 0.05Mpa, and the steam pressure is inseparable from the design and proper installation of the steam piping system. Generally, the moisture content of the raw material before quenching and tempering is about 12%, and the steam pressure is high and the moisture is small. Therefore, the low moisture material can be selected to have a lower pressure. When the moisture content is more than 16.5% after quenching and tempering, the water content of the prepared pellets is high, and it is not easy to store for a long time; when the moisture is less than 15% after quenching and tempering, the granulation consumes more electricity and the crushing resistance is low. The quenching and tempering temperature is closely related to the steam pressure and steam dosage, and it also changes with the seasons. Generally, the tempering temperature of livestock and poultry feed is about 85 degrees, the room temperature is low in winter, the quenching and tempering temperature should be lower, the room temperature is higher in summer, and the quenching and tempering temperature is higher. The steam pressure is high, the amount of steam absorbed by the material is small, and the gelatinization is poor, which is suitable for materials with high moisture content. The steam pressure is low, the material absorbs a large amount of steam, absorbs more water, and has good gelatinization, which is suitable for materials with low moisture content.

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4. Production operations

Correctly control the gap between the pressure roller and the die. The roll gap is too small, the stamper and the press roll are easy to wear, and the super noise is large; if the gap is too large, the material is squeezed. Generally controlled at 0.05 ~ 0.30mm. It can be measured with a feeler gauge during adjustment, and it can be visually measured without a feeler gauge. Taking the new mold new roller as an example, it is better to visually test the pressure roller. However, when there is no material, the main mold can not drive the pressure roller, especially the new mold should be equipped with a new roller, and the gap should be smaller. In addition, the pressure roller should be filled with butter (usually selected high temperature resistant No. 7 lithium base grease) to avoid burning the bearing due to excessive temperature. At the same time, the feeding scraper should also be adjusted. Otherwise, it will make it difficult for the material to enter between the pressing roller and the stamping die. A part of the material will be stringed out from the stamper cover boat to form a high particle size. The adjustment result should be the upper edge curve of the scraper. The gap between the die and the die cover is basically controlled between 2 and 3 mm, and the position of the front end of the blade extending into the die should not exceed the undercut of the inner hole of the die. After the various parts of the granulator are adjusted, the mechanism can be opened. First open the granulator, conditioner, feeder, at this time the feeder should be in a small feeding state. In order to prevent the internal debris from entering the die, the external discharge door on the operation door should be opened, and the waste material in the cleaning machine should be mixed. After the impurities are clean, the material can be introduced into the stamper. To be prudent, the hand should hold the handle of the discharge door outside the machine, first let some of the material enter the die, and then observe whether there are particles out of the mold, and pay attention to the current change. If the particles can be produced normally, the current is relatively stable, the fluctuation range is not large, and the rated current is not reached, then the material flow rate can be increased, and the amount of steam can be increased at the same time until the rated current is reached. If the material enters the granulation chamber, but no particles are ejected, and the current is constantly rising, it is necessary to open the discharge door outside the machine and observe whether the current drops when the continuous feeding is continued. If the current drops and some of the particles are out of the mold, you can hold the handle of the discharge door outside the machine, let some of the material be introduced into the stamper, and part of the material is discharged, observe whether the current is stable, and whether the die is granulated properly. Introduce the stamper. If the current does not drop after stopping the feed, or even continue to rise, it should be stopped to check the cause and the treatment is treated. It is worth reminding that when starting the material, do not rush to add steam, because at this time the material is small, the steam is difficult to add to the ideal amount, the steam is more, the material is less, and it is easy to block the machine, it is not as good as when the material is added to a certain amount. Add steam to be safe. In addition, the granulator must be added to the stamper before the machine is shut down. The purpose of the granulator is to prevent the material in the die hole from becoming hard, so that the next time the die can be granulated smoothly.

5. Ring mode

Whether the material can be squeezed through the die during the granulation process depends on the amount of pressure and friction that can be generated in the die hole. This is related to the coefficient of friction between the material and the wall of the die, the moisture content, the particle size of the material, the temperature, the buffering time of the plastically deformable part of the material, and the compressibility of the material. These characteristics are closely related to the hole depth and the pore diameter of the die. Generally speaking, the compression ratio of the die diameter is preferably 1:8 to 1:13 (that is, the effective thickness ratio of the die hole to the die), the compression ratio of the die is small, the effective length of the die hole is short, and the material is in the die. The pressure formed in the hole is small, and the ring mold is easily extruded. Therefore, the yield is high, but the produced particles are loose, the powder content is high, and the appearance is not smooth; on the contrary, the longer the effective length of the compression hole, the material is in the die hole. The higher the pressure, the higher the compactness of the particles, the better the smooth quality of the particles, the lower the powder content, but the granulator output will decrease, and the electricity consumption will increase accordingly. Therefore, when the feed manufacturer produces pellets of different specifications and varieties, the annular mode aperture ratio selected will be different.