Cause Analysis and Measures For Blocking Machine Of Pellet Mill
Blocking machine is the most common phenomenon in granulators production, when blocking,a layer of hard and thick material accumulates between the die and roller, the roller can not squeeze the material out, the pellet mill can not work. Blocking the machine not only delays production, but also affects the life of granulating equipment.The following are the reasons for the pellet mill blockage and the measures to be taken from the following aspects:
1.Gap between ring die and rollers
When the gap between ring die and rollers is too large,the material layer between the die and rollers is too thick and unevenly distributed, and the rollers are easy to slip.Once the die roller has a compressive force against the material, it is less than the resistance of the inner wall of the die hole to the material, If the material is not squeezed out, it will cause blocking.To reduce the blocking, in the production, should adjust the appropriate gap between the die and rollers, generally is 0.1-0.3mm, make the rollers and ring die close to each other, but not really close.
The quality of the steam is poor so that the moisture is too high after the material conditioning. After entering the pellet mill, the ring die hole is easily blocked and the rollers slip, resulting the machine in blocking. Specific performance:(1)Insuffcient steam pressure and high water content make it easy for materials to absorb too much water. At the same time, when the pressure is low, the temperature of the material is also low when conditioning, the starch can not gelatinize well, the granulation effect is poor. (2) the steam pressure is not stable, and it goes up and down suddenly. The granulatorss needs to adjust the feeding quantity at any time to make the steam quantity reach the best level. If the granulators is not careful, the water content of the material after conditioning will be too high, which will easily cause the machine to be blocked. Therefore, the boiler room should provide high-quality and stable dry saturated steam, ensure that the steam pressure is 0.2 ~ 0.4MPa, the temperature is 130 ~ 160℃, and the steam pressure variation amplitude is not more than 0.05MPa.In order to reduce the impact of condensed water in the pipeline, the granulators should exhaust the condensed water before granulating, and check the water trap width and gas-water separator at any time. During the production, the granulatorss should check the moisture content of the materials after conditioning at any time, generally controlled at 15.5% ~ 17%, not exceeding 18%.The judgment method is to grasp a batch of conditioning materials and hold them lightly into a group.
In producing pig feed containing whey powder, milk substitute powder or sucrose, the method of "low temperature and high speed" should be used. Raw materials such as whey powder, milk substitute powder and common sugar have strong hygroscopic properties and are easy to coking at high temperature,when the temperature of pellet mill is too high, the material is easy to agglomerate between the die and rollers to form a layer of material spot, causing blocking machine. Therefore, the pelleting temperature of Suckling pig should be controlled at 65 ~ 75℃, and the production speed should be fast.
Improve the opening ratio of the ring die and the smoothness of the die hole, reduce the step resistance and increase the discharge speed. For the ring die, the opening ratio is low which not only affects the output, but also easily blocking the machine. Due to the poor smoothness of the die hole and high material resistance, the new ring mold needs polishing treatment, during polishing, oil sands (sand 10%, soybean meal 10%, rice bran 70%, oil 10%) can be cleaned for 10-20 minutes with 50 ~ 100kg. After each granulation, clean the ring die with oil containing 20% oil for 5-10 times and let the oil material fill the die hole instead of the original material so that the oil can be easily pressed out when the machine is turned on next time, reducing the blocking.
If there is a blockage in the production, a thick layer of very tight material is often formed between the die and rollers. If it is a slight blockage, pour a layer of oil onto the material layer, let the oil infiltrate and then start the motor until the ring die rotates normally.If this method is invalid, do not start it multiple times to avoid burning the motor. At this time, only increase the gap between die and rollers, then remove the materials then start the production.