Design Of Wet Feather Twin-screw Extrusion System And Optimization Of Working Parameters

In the past 40 years,China’s animal husbandry has developed continuously and stably.Under this background,how to solve the shortage of protein feed resources has become an urgent problem to be solved.With the development of animal husbandry,a large number of waste feathers will be formed.These waste feathers are rich in protein resources,but most of them are keratin.Because the keratin in feathers has a stable internal spatial structure,it can not be directly absorbed and utilized by livestock.Therefore,in order to make rational use of these protein resources,feather expansion technology has emerged in line with the times.However,at present,the feather expansion technology in China is not mature,and the raw material of feather extrusion machine is only dry feather.At the same time,the problem of how to adjust various parameters in extrusion processing to make the quality of expanded feather powder better has never been involved.In view of the above problems,the main research contents of this paper are as follows:(1)Taking a chicken feather as a sample,the physical and mechanical characteristics of the chicken feather are reflected by measuring its moisture content,bulk density,and friction characteristics,and the extrusion mechanism of the feather are analyzed,to analyze and explore the morphological changes and changes of various nutrients caused by mechanical and thermal effects in the extrusion process,It provides basic data support for the design of subsequent drying device and orthogonal test.(2)The method of hot air drying was used to dry wet feathers,and the drying characteristics of feathers were measured.1106 goose feather smoke removal drum dryer is selected to dry wet feathers.The feed hopper of the dryer is checked through the measured physical characteristics of wet feathers.The performance of the dryer is further verified through the calculation of key parameters of hot air drying,and the operating parameters of the machine when the machine outputs feathers with different moisture content are determined.At the same time,the screw,the key component of the extrusion system of the twin-screw extruder,is designed.(3)The influence of main working parameters on the performance of the machine was explored,and three test indexes of crude protein content,pepsin digestibility,and crude ash content were determined.Four test factors and five-factor levels of feather moisture content,screw speed,heating temperature,and outlet clearance were selected.Four groups of single-factor tests were carried out on the machine,and their effects on crude protein content,pepsin digestibility,and crude ash content were analyzed respectively Pepsin digestibility and crude ash content.(4)To explore the experimental indexes of extrusion performance of twin-screw extruders and the relationship between experimental factors,a set of quadratic regression orthogonal rotation combination tests with three factors and five levels were designed.The upper and lower levels of moisture content of dried feathers were 22%and 14% respectively,the upper and lower levels of screw speed were 70 r / min and30 R / min respectively,and the upper and lower levels of heating temperature were220 ℃ and 140 ℃ respectively.(5)Using Design-Expert software,the regression equation and variance analysis of the designed quadratic regression orthogonal rotation combination test results of three factors and five levels are established,the significant influence of each test factor on the test index is determined,and the significance ranking is carried out according to the influence results of each test factor on each index.The parameters are optimized by Design-Expert software.The optimal parameters are as follows: the moisture content of poultry and livestock feathers is 19.53%,the screw speed of the machine is 55.84r/min,and the heating temperature in the machine cavity is 180.64 ℃.At this time,the comprehensive index of feather powder is optimal.The content of crude protein in feather powder is 95.15%,the digestibility of pepsin is 92.11%,and the content of crude ash is 1.77%.The experimental results show that the error between the results of the verification test and the expected optimal value is less than 5%,which shows that the scheme is feasible.