The Study On The Pretreatment Technology Of Soybean Extrusion Cooking By Twin-screw Extruder For Solvent Extraction Of Oil

The technique of extrusion is a new technology which has advantages in the productivity of extraction equipment,the rate and the energy consumption of extraction,and the ratio of solvent and soy meal comparing with the traditional method of solvent extraction when it is first applied in the industry of oil production from 1960s.Now abroad extrusion machine has as standard equipment in the oil pressing mill.However,the pre-treatment processing,adopted at home and abroad,of soybean extrusion and expansion is rather complex,including unit operations of cleaning,crashing,softening, rolling,expanding,drying,extracting,and so on.In this study using a simple pretreatment process,the soybean meal only needs cleaning,crashing, expanding and extracting.The research on the effects of extrusion process techniques parameters(diameter of die nozzle,moisture content, rotate speed of screw and barrel temperature)on residual oil rate, the production, the per kilowatt-hour yield and shearing strength used the method of second power,revolving,orthogonal and tropical design of four factors and five levels.Provide the basis for the actual production and theoretical foundation. The concrete contents of research and results are as followed.1.The regression equation of extrusion parameters and residual oil rate is set up, the regularity of extrusion parameters and residual oil rate was analyzed.The influence of extrusion parameters on residual oil rate was obtained.2. The regression equation of extrusion parameters and productivity is set up, the regularity of extrusion parameters and productivity was analyzed.The influence of extrusion parameters on productivity was obtained.3. The regression equation of extrusion parameters and per kilowatt-hour yield is set up, the regularity of extrusion parameters and per kilowatt-hour yield was analyzed.The influence of extrusion parameters on per kilowatt-hour yield was obtained.The result shows: influences of extrusion parameters to kilowatt-hour yield is rotate speed of screw, diameter of die nozzle, barrel temperature, moisture content. The optimum parameters of extrusion system were as follows:diameter of die nozzleΦ=26 mm,moisture content W=18%,rotate speed of screw n=160r/min,barrel temperature T=60℃, kilowatt-hour yield is192kg/(kw·h). 4. With the method of illegibility analysis, the residual oil rate,the production and the perkilowatt-hour yield of the extruder were synthetically assessed.The optimum parameters of extrusion system were as follows:diameter of die nozzleΦ=22 mm,moisture content W=16%,rotate speed of screw n=130r/min,barrel temperature T=105℃by the frequency analysis; and the low residual oil rate , high productivity and high per kilowatt-hour yield were assured in this system.5. It was Analyzed that the distribution of residual oil rate within the range of shearing strength .The results show that the extruded material with the higher shearing strength is low residual oil rate. The permeability of the bad situation is solved.6. It was studied that the two technology of pretreatment after soybeans extruded and rolled pretreatment by the technology of paraffin wax section,It point out that the cells of extruded soybeans were broken completely,its fat accumulated and it brought out capillary in extrudate because of the moisture evaporates rapidly after the soybeans were extruded to die nozzle,which is the true reason of shortening the time of oil solvent extraction and low-residual oil ratio.