| The screw configuration is the main component in a twin-screw extruder. Because the raw material is subjected to different thermal mechanical efficiency and residence time distribution in different screw configuration, so lead to different product performance. Because nitrogen solubility index NSI<30%, so it is difficult to achieve high-temperature defatted meal extrusion texturization, and the less study has been reported on extrusion mechanism, screw configuration and extrusion parameters. This article is based on the technology of high-temperature defatted meal extrusion texturization, then, the author studied mathematical model of screw configurations, flow mechanism of material flow in whole runner and the influence of screw configurations and extrusion parameters on target parameters of products, at the same time, achieved important research results.1) According to the meshing principle of intermeshing co-rotating twin screw, the mathematical model and design method of the whole screw configuration were built up.2) Using high-temperature defatted peanut meal as raw material, using TXLL110twin-screw extruder, the influence of three kinds of screw configurations on target parameters of products was studied by comparison experiment. The results showed that the ration between length and diameter of molten area and screw element combination were the main factors.3) The results of numerical simulation showed that coarse pitch single thread screw element could be used in feeding zone. Pressure range0-1MPa, temperature range80-84℃; Forward and reverse kneading block and slotted screw element could be used in melting zone. Pressure range0.9-3.0MPa, temperature range95-153℃; Small and medium pitch double thread screw element could be used in homogenizing zone. Pressure range3.0-3.4MPa, temperature range155-157℃.4) The mathematical models of structure parameters and target parameters were obtained by response surface analysis. The products obtained the optimum structure under the conditions of the ration between length and diameter of screw25.5:1, the ration between length and diameter of molten area12:1, and the diameter of die orifice16mm.5) The mathematical models of process parameters and target parameters were obtained by response surface analysis. The products obtained the optimum structure under the conditions of barrel temperature (zone4)145-147℃, feed moisture30%, feed speed550-560kg/h, and screw speed340r/min. As theoretical basis, the results could be used in the design and study of twin-screw extruder on high-temperature defatted meal extrusion texturization. |
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