Design And Experimental Study Of Key Components Of Twin-Screw Feather Extruder

With the rapid development of China’s poultry and livestock industry,the demand for protein feed has increased sharply.The feather is rich in a variety of amino acids and more than 85% protein,but most of them are keratin.A large number of disulfide bonds and hydrogen bonds in this protein structure interact to form a complex and stable three-dimensional supercoiled space structure.Feeding poultry directly will cause the poultry to be unable to digest and absorb,and the feed value is extremely low.At present,most of the poultry feather waste in China is burying,incineration and other treatment methods,which destroys the environment and also wastes protein resources.The stable structure of feather keratin can be destroyed under high temperature and high pressure,and then converted into crude protein that can be absorbed and utilized by animals.In response to the above problems,this thesis carried out feather puffing research and designed a twin-screw feather extruder,which uses dry chicken feathers as raw materials to produce protein feed puffed feather meal.The processing and utilization of the existing protein resources are realized,and the environmental pollution caused by the existing poultry feather waste is reduced.The main research contents of this thesis are as follows:(1)Taking broiler feathers as the research object,the geometric dimensions and physical and mechanical properties of broiler chickens were measured and analyzed.The chicken feathers after drying and drying are measured by related equipment and related physical characteristics such as moisture content,bulk density,friction angle,natural angle of repose and so on.It provides a basic reference for the design of the feeding device and the expansion device of the twin-screw extruder below.(2)Due to the uneven shape,poor fluidity,light weight and easy entanglement of chicken feather materials,in order to achieve the purpose of uniform feeding and stable puffing,a spiral conveying feeding device is designed.First,according to the physical characteristics of the feathers,the configuration of the hopper was selected and the requirements of the hopper design were put forward.Secondly,the overall structure of the screw conveyor is determined by analyzing the types and characteristics of the screw conveyor.Finally,the working state of the screw conveyor is analyzed and the parameters of the key components such as the screw blade diameter,the pitch and the shaft diameter of the mandrel are calculated according to the feed amount.(3)By analyzing the expansion principle of the twin-screw extruder and the extrusion process of the material,the microscopic principle of chicken feather expansion under the action of the twin-screw extruder is summarized.The combination of twin-screws with meshing and counter-rotating is selected,and its relative motion principle and geometric theory are analyzed.On this basis,the screw configuration is designed through theoretical analysis,the combined screw structure is selected,and the diameter of the screw and the length of the effective working area are determined.The key parameters such as the center distance of the two screws,the length of the screw elements of the conveying section,the compression section and the melting section and the pitch,the shape of the thread section,and the depth of the groove are designed,and by adding shearing elements to improve the shearing force of the screw on the feathers.Finally,the types and advantages and disadvantages of external heating and cooling devices are compared,and the cast copper heater and water-chilling plant are selected considering the actual situation.(4)In order to verify the expansion effect and working performance of the designed twin-screw feather extruder,prototype trial production and experimental exploration were carried out.First of all,taking feather puffing degree and the crude protein content of the puffed feather meal as a reference basis,it is found through experiments that the screw speed is within the range of 50～55 r/min for the best feather processing effect.Secondly,take feather puffing degree,feather meal crude protein content,crude ash content,pepsin digestibility and various amino acid content as test indicators.At the puffing temperature 200℃,the feather material moisture content is less than or equal to 20%,and the feeding amount.The verification test is carried out under the test conditions of 60g/s and the twin-screw speed of 55r/min.The results of the test found that the expansion degree of feather material is about 2.557,the crude protein content in the puffed feather meal is about 89.82%,the crude ash content is1.706%,the pepsin digestibility reaches 93.2%,and the output can reach 172.02kg/h.The whole machine runs stably and extrudes evenly when working continuously.The processed puffed feather meal has a high crude protein content and extremely low ash content.The pepsin conversion rate is high,and the whole machine has a great processing effect.