In the actual production of feed, due to a variety of reasons, a "material crust" will be formed between the ring die and the pressure roller, resulting in problems such as jamming, blockage, and slippage of the pelletizer.
Through actual analysis and experience of the case site, we have reached the following conclusions:
1. Raw material factors
Materials with higher starch content are easy to be gelatinized by steam and have a certain viscosity, which is conducive to forming; for materials with higher crude fiber, a certain amount of grease needs to be added to reduce friction during the granulation process, which is conducive to the material passing through the ring die and forming The granular material has a smooth appearance.
2. The gap between the mold rolls is inappropriate
The gap between the mold rolls is too large, which causes the material layer between the mold rolls to be too thick and unevenly distributed. The uneven force on the pressure roll is easy to slip, and the material cannot be squeezed out and the machine will be blocked. In order to reduce machine blockage, attention should be paid to adjusting the die roll gap during production, generally 3-5mm is better.
3. The influence of steam quality
The ideal conditions for the granulation process are: the raw material has the right moisture content, the steam quality is good, and there is sufficient quenching and tempering time. To ensure good pellet quality and high output, in addition to the normal operation of each transmission part of the pellet mill, the quality of the dry saturated steam entering the pellet mill conditioner should also be ensured.
The poor steam quality makes the moisture of the material too high when it exits the conditioner, and it is easy to cause blockage of the die hole when the granule cavity is formed, and the pressure roller slips and causes the machine to block. Specifically in:
①Insufficient steam pressure and high water content make the material absorb too much water. At the same time, when the pressure is low, the temperature of the material when it is tempered is also low, the starch cannot be gelatinized well, and the granulation effect is poor;
②The steam pressure is unstable, high and low, and the material conditioning is unstable, resulting in large fluctuations in the current of the granulator, uneven material thirst, and it is easy to cause the machine to block in the normal production process.
In order to reduce the number of machine blockages caused by steam quality, feed factory operators need to pay attention to the moisture content of the material after conditioning at any time. The simple judgment method is: grab a handful of the material from the conditioner and hold it into a ball with your hand, and let it go. .
Fourth, the use of the new ring die
Generally speaking, when a new ring die is used for the first time, it needs to be grinded with oily materials. Appropriately increase the emery by about 30% and grind for about 20 minutes; if the same amount of material is placed in the grain chamber, the current will be lower than that during grinding. Relatively stable, with small fluctuations. At this time, you can stop the machine, depending on the granulation situation, and the granulation is uniform and reaches more than 90%. At this time, use oily material to press in to replace the sand material to prevent material blockage next time.
Five, how to eliminate blockage
If the ring die is blocked during the production process, many feed mills use electric drills to drill the material out, which will damage the finish of the die hole and is not conducive to the appearance of the pellets.
A better method is recommended to use oil to boil the ring mold, that is, use an iron oil pan, put in waste engine oil, put the blocked mold in it, and then heat and cook it through the bottom until there is a popping sound, and then take it out. After cooling, the installation is completed, and the machine is restarted according to the operating specifications of the granulator, and the materials blocking the ring die can be quickly cleaned without damaging the finish of the granules.
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