Parameter optimization of granulated alfalfa pelleting process based on extrusion simulation experiment

To obtain the best pelletizing process of alfalfa pellet, the granulated alfalfa as the pelletizing material, through the simulation experiment of pelletizing with ring die and using the quadratic regression orthogonal rotational combining design, the relationships of granulation density with extrusion force, material moisture content and size were studied, and the mathematical model between factors and the density of the granulation was established. The result showed that: regression equation was significant; the three factors affecting the density of the granulation was: extrusion force > material moisture content > size. Through the simulating excellent-choosing equation, the best parameter combination under the simulation experiment conditions was obtained as follows: extrusion force was 5.47 kN, the material moisture content was 16.96%, size was 6.34mm, the density of the granulation was 1.241g/cm3. The results can provide academic guidance for improving the quality of alfalfa pellet or other granular products.