Analysis and selection of aquatic feed extruder?

Aquatic puffed materials have gradually replaced hard pellet materials and become the mainstream of aquatic feed. The production process of aquatic puffed feed generally includes raw material crushing, mixing, secondary micronization, extrusion and puffing, drying, cooling and other processes. Among them, extrusion and puffing play a very important role in the entire process, and have a greater impact on the quality and production efficiency of the feed. big. The extruder is mainly composed of a barrel and a screw that rotates in the extruder barrel. There are two categories: single-screw extruder and twin-screw extruder. During the extrusion process, the material enters the die cavity from the feeding port and is extruded, mixed, compressed and sheared when pushed forward by the screw. Due to the driving force, friction force, shearing force and external heating, the material is heated under pressure, reaches a high temperature and high pressure state, and matures into a modified paste. When the material is extruded from the front die hole, the temperature and pressure suddenly drop to normal temperature and pressure, causing the water in the material to vaporize and evaporate rapidly, and the volume expands rapidly to become a puffed product.

The screw of the single-screw extruder consists of a shaft connecting screw units of various structures. The entire screw consists of three sections: feeding section, kneading section and melting homogenization section. After the material enters the barrel from the feeding port, it undergoes solid transportation, melting and homogenization processes in the screw, transforming the material from a loose state into a continuously plastic dough shape. In the single-screw extrusion chamber, the material basically surrounds the screw tightly, in the shape of a spiral continuous belt. When the screw rotates, the material moves forward along the spiral like a nut, but when the friction between the material and the screw is greater than the material When there is friction with the barrel, the material will co-rotate with the screw, so the forward extrusion and transportation of the material cannot be achieved. The twin-screw extruder is a kind of multi-screw extruder. It is developed on the basis of the single-screw extruder. In the barrel of the twin-screw extruder, two screws are placed side by side. Therefore, it is called twin-screw extruder. The twin-screw extruder has the advantages of strong adaptability, slip conveying and self-cleaning, but its structure is complex, the investment cost is high, and the corresponding maintenance and operating costs are also high. Everyone can choose according to their actual needs.