The mixed powdered feed is pelletized, which can improve the nutrition and edible quality of the feed to varying degrees. Northern feed machinery, pelleting is not only suitable for livestock and poultry feed, but also suitable for aquatic products and special feed. Due to the different types and components of feed ingredients and different scales of finished products, there are also different requirements for the performance and structural parameters of the pelleting equipment. The granulation process is generally equipped with granulating, cooling, crushing and grading equipment, and some are also equipped with a grease spray system. The selection principles of the above-mentioned equipment are as follows:

　　1, granulator

　　 The pellet mill used in the feed mill has two types: ring die and flat die. The flat die is more suitable for the pelleting of coarse feed, so only the ring die pelletizer is described. Since the working principle of the ring die granulator is basically the same, the performance evaluation of the model selection is mainly from the rationality of the structural design, the convenience of operation, the selection of structural parameters, the processing methods, the manufacturing level, the selection of parts and components, the purchase channels and The control function and other aspects are comprehensively considered.

　　2, cooler

　　 cooling is to keep the product after granulation better storage performance, it is an indispensable procedure after granulation. For a long time, cross-flow cooling has been used for cooling after granulation. Although it can meet the requirements of use, the temperature of the cooled particles is less than 7oC, but it is easy to fail to meet the standard if you are not careful during operation. Therefore, the counter-flow cooler that has recently appeared is a model with a more reasonable cooling principle, because the convection heat exchange system is the most complete and reasonable. The machine was quickly promoted as soon as it appeared. The cooling effect of this machine can be 3oC lower than room temperature, and the cooling effect is extremely ideal. The model selection of this machine, because the models produced by various factories are similar, so we should pay attention to the manufacturing quality, materials and accessories, such as: how the automatic control effect of the feeding and discharging linkage mechanism is, and whether the main part is made of stainless steel. In addition, the output selection can not only use large-size models, but also increase the output after stacking two machines, which has a great effect on the selection and use of fans and separators. The suction pipe should be made of stainless steel sheet, otherwise the service life will be greatly affected in the presence of water vapor, and attention should be paid to it, otherwise it is impossible to obtain the most ideal use effect.

　　3, granulator

　　 Crumbs can save power consumption and improve the digestion and absorption rate of livestock and poultry. At present, almost all crushers use roller crushers, and their performance is mainly evaluated by the rationality of the machine's structure, structural parameters, process parameters, and processing level. The roll diameter is large and the pressure is large, and it is easy to break. There are two types of roller tooth profile, one is the crossed helical teeth, and the front-to-front is suitable, the number of teeth should not be too much, which reduces the powder yield; the second is the combination of straight and helical teeth, this combination The disposal rate is also relatively small, but the two types of tooth profile arrangements can meet the requirements of use, and the powder extraction rate should be controlled within 3%. But starting from actual use, it is very important to adjust the distance between the two rollers. Otherwise, the product will be uneven when the distance between the two rollers is not equal. You can set a ruler at the adjustment handwheel for easy operation. In addition, attention must be paid to the inlet size of the granulator when selecting the model, and it must be completely consistent with the outlet of the cooler, otherwise the powder output rate will be increased.

4. Grading screen

　　After the crushed material is classified, the powder part is removed to ensure that the material has pure small particles, so that the feeding effect is optimal. The existing classifying screens mainly include vibrating classifying screens and rotary vibrating screens, both of which can achieve better results. The vibration grading screen should adjust the amplitude of the screen body according to the nature and flow of the material to achieve the best effect. Rotary vibrating screen has better classification effect due to the long screen surface distance, and it is also one of the commonly used equipment. In short, these two types of models can meet the requirements of use, and the classification efficiency can reach 98% to 99% or more.

　　 5. Matured

　　Maturation is a process set up to improve the gelatinization degree of feed, improve the water resistance of pellet feed, and also improve the pelleting performance and eating quality.

　　 The maturation process is still in its infancy. At present, the post-curing process uses a curing stabilizer with a steam adding system and a jacket heat preservation device to keep the material temperature at 80oC～90oC, and the particles can be kept in the machine for 20～40min (adjustable) to make the starch paste in the granules It can form a network structure, which can meet the requirement of water resistance of more than 6min.

　　6, extrusion (expansion) device, extruder

The working principle of the extrusion expander is very similar to that of the extruder, mainly due to the large difference in structural parameters and process parameters. For example, the screw compression ratio is 1.05～1.2:1, the extrusion chamber is stable at 120oC～130oC, and the working pressure in the extrusion chamber is 9.8×10-5～4.9×10-6Pa. The damage rate of harmful factors is above 80% to 90%, and the gelatinization degree of starch is 85% to 90%. In addition, whether the material of the screw and screw sleeve is alloy steel, whether the processing method is reasonable and advanced, and the performance after heat treatment, these parameters have a direct relationship with the use effect, which cannot be ignored and must be understood.