Research On Equipment And Technics For Granulation Of Feed Enzyme Pellets

Granulation of feed-enzyme is a relatively new topic. The technical problems to be solved is in three aspects: controlling the particle size, e.g. the average diameter of pellet is about 40 mu; larger producing capacity; controlling the temperature in granulation process because higher temperature will damage the activity of enzymes.The techniques and equipment for granulation of feed-enzyme by the mean of extrusion rolling are studied in this paper. The structures and characteristics of single-screw extruder and revolving extruder are mainly focused; their actual effects of extrusion are tested and evaluated.For single-screw extruder, the helix angle is a very important design parameter, need to be chosen reasonably. Appropriately increased helix angle can strongly promote the impetus of the forward movement of materials, resulting in enhancement of production efficiency. But if the helix angle is too large, screw manufacture will be more difficult and the effect would be limited; Rev has significant impact on production efficiency and extrusion temperature, as well as the nature of extruded material. A suitable rev was chose by experiments. The impact of formulations related to enzymes state (liquid, powder, etc.) on extrusion effect were also tested and evaluated. Single-screw extruder behaves the good characteristics of granulation of feed-enzyme pellets, but its production capacity is relatively lower due to the limiting of screw size.Revolving extruder is in another extrusion form, the rotary blade squeeze the material out of cylindrical sieve screen. For revolving the extruder, the rev still has important impact on production efficiency and extrusion temperature. Formulation and rev were mainly studied. As larger extrusion-screen size, the revolving extruder can granulates feed-enzyme in large-scale and the pellets with the average diameter between 0.6 mm ~0.8 mm. Compared the single-screw extruder, the production capacity of revolving extruder is great.For revolving extruder, the thickness of extruder sieve screen is a very important design parameters, it must be carefully choose, Its thickness is hoped to be in smaller values result in less extrusion-resistance, less temperature rising. In guarantee of adequate strength of sieve screen, finite element analyses was used to analyzed the stress and design the thickness of sieve screen.Extrusion- rolling can produce pellets in higher efficiency with lower extrusion temperature. Orthogonal tests were carried on to identify the best conditions to create the appropriate pellets with starch as tested materials.Pellets of phytase were tested by extrusion- rolling equipment. The activity of fermentation enzyme, after concentrating, reached more than 10000 U/ml. Through the research on formulation of material and application of extrusion- rolling, enzyme activity of the dried phytase pellets could reach more than 5000 U/g, meeting the actual requirements of the enzyme activity. Phytase pellets are in uniform size with narrow distribution, high yield, good mechanical strength and ratio of enzyme activity reservation is also higher. Therefore, Extrusion- rolling is an ideal mean for granulation of feed- enzyme.