| The difference characteristics of each component of safflower impurity mixed material are small,which leads to the problems of high impurity content and loss rate and difficult separation in the separation and cleaning process of safflower,which directly affects the cleaning efficiency of safflower cleaning device.Based on the analysis of the research progress of cleaning devices at home and abroad,combined with the physical and mechanical characteristics of safflower filaments,a pneumatic safflower cleaning device is designed through the combination of numerical simulation and experimental research.It is mainly studied in the following aspects:(1)The physical and mechanical properties of safflower silk and its impurities were analyzed.The triaxial size of safflower filament and the suspension velocity in different suspension stages were measured,and the friction coefficient,collision recovery coefficient and stacking angle parameters were measured and studied.The discrete element model of different components in filament mixture was established by using coordinate filling method.Combined with the simulation study of stacking angle,the discrete element parameters were calibrated,and the rest angle of dry safflower filament stacking angle test was taken as the response value,The parameters of the discrete element simulation software are independent variables.Plackett Burman(PB)test,steepest climbing test and central composite test were carried out successively.The discrete element simulation parameters of safflower filaments were optimized.The significant influencing factors of stacking angle were obtained: the static friction coefficient of filament-filament was0.21 and the rolling friction coefficient of filament-filament was 0.12.The discrete element simulation test results were compared with the physical test of safflower filament stacking,and the relative error was 1.15%.The accuracy and reliability of the discrete element parameter model of different components in filament mixed materials are verified.(2)The overall structure of the pneumatic safflower cleaning device is designed,mainly including cleaning mechanism and feeding mechanism.Study the working principle of the cleaning device,analyze the separation process of filaments and impurities under the action of air flow field,analyze the force change of particles,establish the motion model of filaments and impurity particles under the action of air flow field in the separation chamber,and find out the factors affecting the motion trajectory of filaments particles.According to the existing research and theoretical calculation,the motor,fan and reducer are selected.Through the design and selection of key components,the important working parameters of air flow angle,dust removal port angle and air flow velocity are determined.(3)The numerical simulation test method is used to study the single factor parameters,and the migration law and motion characteristics of small stones,cohesive filaments and safflower filaments in the pneumatic separation and cleaning process are found.The separation and cleaning process between safflower filaments and other materials in the pneumatic safflower cleaning device is numerically simulated by cfd-dem coupling method,The variation curve and movement track of the average velocity in the cleaning chamber during the separation and cleaning process of filaments and other materials were obtained,and the movement track and average velocity variation trend of each component of filaments and impurities mixed materials with time in the cleaning chamber were studied.(4)Build a test bench for cleaning performance test.The mathematical models between various factors and impurity content and cleaning loss rate are established based on the independent variables of air flow angle,dust removal port angle and air flow velocity,and the impurity content and cleaning loss rate of filaments are taken as the response values.The factors and their interaction are analyzed,and the optimal working parameters of the pneumatic safflower silk separation and cleaning device are obtained.The results show that when the air flow velocity is 7m / s,the air flow angle is 0 ° and the dust removal port angle is 25 °,The cleaning effect is the best,with impurity content of 0.69% and loss rate of 2.75%.By controlling the motor speed of the feeding device,controlling the feeding amount and working environment,and arranging the cleaning performance verification test according to the working condition of gas-solid two-phase flow numerical simulation,it can be seen from the test results and particle size distribution that the impurity content is 0.72%,that is,0.03 percentage point lower than the predicted value.The loss rate is 2.75%,which is 0.09 percentage point lower than the predicted value.The comparison results between theoretical optimization and experimental results show that they are relatively close. |
