| With highly developed feed-line business,small-scale feed pelleting system is mandatory during the process of the utilization of new feeding raw material,the customization,diversity and delicacy development and production of new fodder and its side-products.But there is still a non-negligible distance for the existing national small-scale feed pelleting systems for being considered to be developed.Focusing on this issue,the objective of this research is to study the friction and thermal properties of feed raw material,design and optimize the major parts of the system,optimize the operating parameters.The results are as follow:(1)The friction and thermal properties of six kinds of major feed raw materials(maize meal,barley meal,wheat meal,soybean meal,DDGS and whey powder)and one kind of typical formula feed,as well as the relevant law of their properties with different wet basis moisture conetnt and particle size were obtained.It provided the basic data for the utilization of feeding raw material and the simulation and optimization afterwards.(2)The feeder parameters optimization was conducted.Based on the theory of quadratic orthogonal rotation design,the spindle diameter,pitch of screw,and the feeding rate were selected as the influencing factors,and the feeding mass flow rate,stability,drop speed of the materials were selected as evaluating indicators,by using regression analysis and response surface analysis method,we could get the optimal aggregative index:the spindle diameter was 35 mm,the pitch of screw was 57 mm and the rotation rate was 23.2 r/min.The stability of the feeder was improved.(3)The study of conditioner's CFD-DEM modeling and simulation,model selection and design of conditioner structure,its parameter optimization,as well as its modeling and simulation were conducted.First,the structure parameters of axial gas intake conditioner would be better for the thesis,based on the coupling method CFD-DEM.Next,the structure parameters of axial gas intake conditioner were designed:inner diameter was 0.1 m,length of conditioning section was 0.6 m.At last,the blade installation angle,speed of conditioner,and speed of feeder were selected as the influencing factors,and the productivity of conditioner,conditioned material temperature were selected as evaluating indicators,based on the regression analysis and response surface analysis method,the optimal aggregative index could be obtained:the blade installation angle was 38.1°,speed of conditioner spindle was 220.6 r/min,and speed of feeder was 17.4 r/min.Under this scheme,the productivity of conditioner was 12.7 g/s and the material temperature after conditioning was 65.0 ?.In this case,the conditioner had the proper productivity and the conditioned material temperature was within the scope of the technical requirements.(4)The number of roller,as well as structural parameters was designed and optimized.First,based on that the ring die diameter was 180 mm,length was 15 mm,the maximum roller size with the different grab angle and height change was analysed;the conclusion was that if it was two roller combination,the pressure roller diameter was 70 mm;and if it was three roller combination,the diameter was 64 mm.Then,the theoretical productivity of the combination of the bigger and small roller was analyzed,the parameters was obtained:the number of roller was 2,the diameter of the roller was 70 mm,and the eccentric mounting distance was 5 mm.Finally,based on the finite element analysis software ABAQUS,the extrusion process was analyzed.The results show that:the choice of larger friction coefficient of materials could reduce the slippery energy consumption;appropriate reduction of gap between die and roll could increase the extrusion stress and improve the quality of pellet feed.(5)The single-mode hole extrusion simulation was analyzed;a single-hole test platform was designed and built for experiment study.The software ANSYS was used to simulate the extrusion process,and the results showed that:when the material was closer to the wall of the die hole,the stress and strain would be bigger;when it entered to the chamfering area,the equivalent stress of the raw materials would increase;when it entered to the through-hole area,the equivalent stress would change slowly.Based on the self-made single-hole test platform,the relaxation and hardness of pellet feed with different moisture content,heating temperature and load were studied.The results showed that:the residual stress sharply decayed,with more than 80%of the decaying stress occurriing within 30 second.The higher the applied load was,the larger the residual stress was.The load and moisture content affected the residual stress and the feed's hardness obviously(P<0.05).The relaxation modulus increased with the increase of load and decreased with the moisture content;the higher the moisture content and the bigger the load were,the bigger the pellet feed's hardness would be. |
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