Analysis on the conditioner effect factors of animal feed pellet machine and feed extruder machine
Due to the performance difference between the animal feed pellet making machine and the feed extruder equipment, the conditioner of the extruder is usually one layer, and some models have two layers. But the conditioner configuration of the ring die animal feed pellet mill machine is more flexible, divided into single-layer conditioner animal pellet machine, double-layer conditioner feed pellet machine and triple-layer conditioner feed pellet mill.
Conditioning is an indispensable process for granulation or expansion. Without a good conditioning system, there will be no excellent granulation or expansion effect. However, there are many factors that affect the conditioning effect of the conditioner, which mainly depends on the following three factors.
1. Material performance
(1) Material properties
Because there are many types of feed components, the nature of their materials is different, and the effects of conditioning are also different. According to its main components, the material properties are divided into protein type, starch type, fiber type, fat type, heat-sensitive type, etc. The operating parameters should be different during conditioning.
Protein is hydrophilic, and the water content should not be increased too much during conditioning, otherwise it will easily block the film pores. For this reason, it is better to use superheated steam, because the conditioning of protein feed is more important than heat.
Starch needs high temperature and high humidity conditioning conditions, so it is advisable to use low-pressure superheated steam or add some water in the feed mixer machine.
③ Fiber feed
The fiber has poor water retention and cohesiveness. Therefore, the moisture content should not be too high, generally 13%-14%, and the material temperature should be controlled at about 55-60℃. If the material temperature is too high, the compressed pellets are prone to cracks. Use lower superheated steam or add a small amount of water in the mixer to reduce the material temperature during compression.
④ Fat feed
The moisture content of fat feed should not be too high. For this reason, the use of higher superheated steam is beneficial to fat pelleting.
⑤ Heat sensitive feed
The heat-sensitive feed strives for a low tempering temperature, and the material temperature is controlled below 60℃. The moisture content should not be high. Therefore, it is effective to reduce the material temperature by using lower superheated steam or adding a small amount of moisture in the fodder mixing machine.
(2) The particle size and uniformity of the material
Because there are many types of feed components, and the particle size and uniformity of the same type of powdery materials are also different, this brings certain difficulties to the operation of the conditioner and puts forward higher requirements. Because the quenching and tempering requires that the center of each particle is softened, if the quenching and tempering of small particles has reached the requirements, the quenching and tempering of large particles has not yet reached the requirements. If the particle size difference is larger, the tempering effect will be larger. The latest foreign research conclusions: "The influence of the particle size of powdery particles on the quenching and tempering effect" is proposed, and the particle size of the material is as close as possible to facilitate the uniform quenching and tempering effect. For this reason, for large-scale feed mills with high requirements for conditioning, pellets can be classified first, and then the process of conditioning, to achieve the best conditioning effect, while saving energy consumption.
(3) Moisture of materials
Moisture is an important factor affecting the conditioning effect. Under the same conditioning temperature and conditioning time, the moisture content of the material is high, and the conditioning effect is better than the material with low moisture. Due to the poor resistance of microorganisms to damp heat, the microorganisms can absorb high-temperature water in the surrounding medium under the action of steam, which promotes the coagulation of microbial cell proteins and accelerates the death of microorganisms (the death time of microorganisms in hot and humid materials is relatively low 1/3 of moisture content). Therefore, under the condition of high moisture content of the material, molds such as Salmonella and pathogenic bacteria, phytohemagglutinin, protease inhibitor harmful factors are destroyed and inactivated, and the starch gelatinization degree is also high.
2. Conditioner performance
（1）Conditioner structure and process parameters
①Is the conditioner a single-layer conditioner or a three-layer conditioner; is the conditioner a long (3-4m) or short (below 2m) conditioner; is it a double-tube conditioner or a single Barrel conditioner; is it equal diameter conditioner or differential conditioner; is it a large diameter conditioner or a smaller diameter conditioner; is it a normal pressure conditioner or a high pressure conditioner, the difference is The structure has a greater impact on the quenching and tempering effect. Such as: the conditioning time, the addition amount of the conditioning liquid component, and the conditioning maturity are all different.
Therefore, for shrimp feed with high water resistance requirements, the proportion of liquid components added is relatively high, and it is better to use a conditioner with a long conditioning time and high conditioning speed, such as a differential cylinder conditioner. Three-layer conditioner, double-tube conditioner, and differential conditioner can be used for fish feed with low water resistance requirements. As long as the angle of the conditioner blade is adjusted to control the conditioning time, the conditioning can be satisfied. Requirement, but compare the economics of investment. Generally, single-cylinder large-diameter conditioner and double-cylinder conditioner can meet the application requirements. Differential barrel conditioner, three-layer conditioner, long-type conditioner, high-speed conditioner, and double barrel conditioner have good conditioning performance. Among them, differential conditioner and double barrel conditioner The quality uniformity is the best, because the differential conditioner solves or improves the uniformity problem of longitudinal tempering. Other conditioners still have the problem of uneven longitudinal tempering to a certain extent.
②The structure of the blades is different, and the tempering performance is still different. The blades of the early conditioners are actually blades, and they have gradually transformed from larger-area blades to small-area blades. Recently, the blades of the conditioner have been changed. In a square rod shape (the number of blades is also an important factor affecting the quenching and tempering effect, and there is little change at present). The quenching and tempering effect largely determines the turning performance of the material. A large blade has a large area, which is beneficial to material transportation, but relatively static materials are more, and the flipping performance is relatively poor. Therefore, the tempering effect is also poor. For this reason, the blades of the conditioner gradually develop into a square rod shape with a certain area. The increase in the number of blades reduces the material conveying capacity, prolongs the conditioning time, and has good flipping performance, thereby improving the conditioning effect.
（2）Speed of conditioner
The speed of the conditioner with the same diameter has a greater influence on the quenching effect. The high speed enhances the flipping performance of the quenched and tempered material, and also increases the speed gradient of the steam on the surface of the material, thereby accelerating the quenching speed and effect. At the same time, the speed of the blade is high and the impact force is large, which accelerates the diffusion of water into the material. Therefore, a high-speed conditioner has a better conditioning effect, and after the addition ratio of liquid components can reach 10%, it still has a better conditioning effect.
Any heat transfer, quality (moisture) transfer takes time to get the best conditioning. Moreover, different finished materials have different crushing particle sizes, different maturation requirements, and different structure of the conditioner, so the requirements for quenching and tempering time should be different. Generally, the conditioning time of poultry and livestock feed is about 30s, and the conditioning time of fish and shrimp feed is up to 2-20min. In short, the conditioning time has a great influence on the quality of the conditioning. The tempering time can be increased by adjusting the angle of the tempering device, changing the length of the conditioner and adding a heat preservation and homogenizing system, so that the material can get a better tempering effect. At present, adding a thermal homogenizer to the granulator can improve the quenching and tempering effect to varying degrees.
3. Tempered steam quality
Because steam of different quality has different temperature and moisture content, superheated steam is of good quality, high temperature and low moisture content, while granulation tempering and puffing tempering have different requirements for material temperature and material moisture content, granulation process Generally, the temperature of the material entering the granulation chamber is 75-85℃, the water content of the material is 17%-18%, and the temperature of the material after granulation is 80-85℃. The extrusion process generally requires the temperature of the material entering the expansion cavity to be above 95°C, the water content of the material is preferably 28%-30%, and the temperature of the material in the expansion cavity is above 130-140°C. Since it is difficult for the material to reach the moisture content of 28%-30% after steam conditioning, water should be added to the mixer or conditioner in the puffing process to make the material moisture reach the requirement of 28%-30%.
Adding water to the conditioner, due to the short action time of water on the materials, the formation of physical and chemical combined water does not meet the requirements of 25%, and a large part of it is mechanically combined water (free water, free water). For granulation, when humidification is required, it is better to add water in the mixer than in the conditioner, so that the added water of the material can easily become physical and chemical combined water. Generally, it is better to add water in the conditioner for granulation and puffing, because water is easy to evaporate from the granules, the stability is poor, and the granules are easy to lose during the cooling or drying process. The added water is very beneficial to heat-sensitive materials. In short, conditioning is an important part of pelleting and puffing. Due to different material components, different finished feed pellet products, different conditioners, various parameters of conditioning should be different.