Research On The Preparation Of Floating Aquatic Feed Based On Twin-screw Extrusion Technology

Our country is a large aquaculture country.In 2016,the output of aquaculture in China amounted to 45 million tons,accounting for about 70%of the total world.With the rapid development of aquaculture,the demand for aquatic feed is also increasing.Especially in recent years,China's demand for aquatic feed is growing rapidly.However,the production of aquaculture feed is still in the stage of extensive development.In some areas,the blind feed is not only a waste of resources,but also a problem of water pollution and aquatic products health.In view of the present situation that the process and technology of aquatic feed can not be solved,the related equipment research and Experimental Research of floating aquatic feed are carried out in this paper.Base on the twin screw extruding technology,saving resources,reducing the cost of feed and improving the working efficiency are achieved.At the same time,the feed production process is optimized and the quality of the feed is improved.This topic is from the Key Laboratory of Modern Agricultural Equipment of Ministry of Agriculture in 2016.According to theoretical analysis and project requirements,the microscopic mechanism of expanded aquatic feed during puffing process was analyzed.It includes five parts:material transformation from orderly to disorder,gas core formation,die swell,bubble growth and bubble stop growth or contraction.The bubble growth process of aquatic feed melt is emphatically analyzed,the physical model of cell growth was applied to the bubble growth,and the corresponding mathematical model was established.Finally,the appropriate constitutive equation was selected to calculate the relationship of the inner-outer pressure,shell of the melt and the radius of the bubble and the cell radius.A feed feeding device was designed to reduce the influence of feed quality on feed quality.It mainly includes 1)the research and dimension design of hopper;2)the structural design and size arrangement of the agitator;3)the selection and dynamic balance of the motor.And the feeding device is produced by the size.Through the single factor test of the production of aquatic feed,the relationship between the screw speed of the screw,the temperature of the outlet of the feed section,the moisture content of the material and the feeding speed on the expansion degree,the volume density,the water absorption and the stability of water in aquatic feed were discussed,and the laws of the effect of each factor on the quality of the aquatic feed were obtained,and make an explanation according to the theoretical analysis.According to the single factor experiment,the orthogonal regression combined experiment of three factors and five level two times regression orthogonal experiment was carried out.Through the Design-Expert8.0 data analysis software,the influence of the interaction between the rotating speed of screw,the temperature of the feeding section and the water content of the material on the expansion degree,the volume density,the water absorption and the dis-solubility of the aquatic feed was analyzed.The law of the independent variable and the dependent variable was clearly revealed through the data and chart.By setting the optimal objective function of the puffing degree,volume density,water absorption and dis-solubility of aquatic feed,the optimum process route is 31 Hz,the temperature of the extruding section is 149?,and the water content of the material is 17.5%.The experimental data were compared with the model prediction data,and the micro-structure of the aquatic feed produced under the optimal process was observed by scanning electron microscope.