The Experiment On The Parameters Of Soybean Extrusion Cooking By Twin-Screw Extruder

At present, the technique of extrusion cooking is a common pretreatment technology in the industry of oil production. Comparing with the traditional method, it has advantages in the productivity of extraction equipment, residual oil rate of low level, the energy consumption of extraction, soy meal and oil of quality, and utilization of Protein. Currently, the study on parameters of extrusion cooking by one-screw extruder is common, except for twin-screw extruder. After reformation and perfect, the twin-screw extruder was used in the research. The test method of second power, revolving, orthogonal and tropical design of four factors and five levels and the data processor named SAS9.1 was adopted. The influence of extrusion cooking parameters (moisture content of material, temperature of barrel, distance between die and screw, rotational speed of screw) on residual oil rate, NSI, the productivity, the per kilowatt-hour yield, and midst indexes (the pressure of die, the effect of expansion, shearing strength). It was analyzed that the relation of midst indexes and residual oil rate. It was supplied that the basis for theoretical foundation and actual production. The research details were as followed:1.The influence of extrusion cooking parameters on midst indexes was analyzed. It was studied that the distribution of residual oil rate with the range of the midst index. It shows that the high pressure in the die resulted in low residual oil rate; the better the effect of expansion resulted in low residual oil rate; the high shearing strength resulted in low residual oil rate.2.The regression model of extrusion cooking parameter and residual oil rate was built. It was analyzed that the influence of extrusion cooking parameters on residual oil rate. The factors affected on residual oil rate were as follows:distance between die and screw, temperature of barrel, moisture content of material, rotational speed of screw. The optimal extrusion cooking parameters of low residual oil rate are as followed:moisture content of material is 14%, temperature of barrel is 94℃, distance between die and screw is 25mm, rotational speed of screw is 96 r·min-1.3.The regression model of extrusion cooking parameter and the NSI was built. It was analyzed that the influence of extrusion cooking parameters on the NSI. The factors affected on the NSI were as follows:rotational speed of screw, moisture content of material, distance between die and screw, temperature of barrel. The optimal extrusion cooking parameters of the high NSI are as followed:moisture content of material is 12%, temperature of barrel is 75℃, distance between die and screw is 20mm,. rotational speed of screw is 120 r·min-1. 4.It was analyzed that the influence of extrusion cooking parameters on the productivity. The optimal extrusion cooking parameters of the high productivity were as followed:moisture content of material is 12%, temperature of barrel is 112℃, distance between die and screw is 10mm, rotational speed of screw is 134 r·min-1. The factors affected on the productivity were as follows: rotational speed of screw, moisture content of material, distance between die and screw, temperature of barrel.5.It was analyzed that the influence of extrusion cooking parameters on the per kilowatt-hour yield. The optimal extrusion cooking parameters of the high per kilowatt-hour yield were as followed:moisture content of material is 17%, temperature of barrel is 60℃, distance between die and screw is 10mm, rotational speed of screw is 130 r·min-1. The factors affected on the per kilowatt-hour yield were as follows:distance between die and screw, rotational speed of screw, moisture content of material, temperature of barrel.6.With the method of illegibility analysis, the regression model was built in response surface design. For the low residual oil rate, the high NSI, and the high productivity, The optimal extrusion parameters of the extrusion system were as followed:moisture content of material is 14%～15%, temperature of barrel is 84℃～93℃, distance between die and screw is 14mm-23mm, rotational speed of screw is 107 r·min-1～119 r·min-1.