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How did Muyang control pellet uniformity in aquafeed extrusion?

Good pellet uniformity and pleasing appearance are the important and attractive characters for high quality aquafeed. However, the relationship between good pellet uniformity and high production capacity is hard to balance, just like you can't have your cake and eat it too, especially for the single-screw extruder. As the production capacity increases, the pellet uniformity declines. Usually, good pellet uniformity can be gained when the extruder is running at 70~80% of its rated load.

Essentially, the nonuniform extruded pellets are generated by materials lacking homogeneity in the whole feed milling process. From grinding to mixing, conditioning, extruding and forming, material's lack of proper homogeneity in any of these processes will finally cause nonuniform extruded pellets. Fortunately, material homogeneity in the grinding, mixing and conditioning processes is easy to be controlled with available techniques. The most challenge is to control feed mash homogeneity during extruding.

What are the causes of nonuniform feed mash during extruding?

(1)Nonuniform shearing force. The more difference of shearing force brought by extruding screw stressing on feed mash, the more nonuniform gelatinization and the more nonuniform pellet finally achieved.

(2)Different flow rate. Flow rate of feed mash during extruding could be different in two zones: the screw zone and the non-screw zone (between the end of screw and the die plate). The different flow rate of feed mash in the extruder will cause different ripening time, and different gelatinization as well as different pellets quality accordingly.

For a normal extruder, the difference of shearing force and that of flow rate are related to production capacity. The larger the actual capacity that is close to the rated value, the bigger the difference of shearing force and that of flow rate.

In view of above impacting factors, Muyang has developed the so called "turbulent flow extruding technology" to control pellet uniformity in aquafeed extrusion. It is applied to well distribute the shearing force in the screw zone and to unify the flow rate in both the screw zone and the non-screw zone (between end of screw and die plate) in an extruder chamber. The turbulent flow extruding technology can help extruder (especially the single-screw extruder) perform outstandingly in aquafeed production.

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