Simulation And Experiment Of Chili Seed Treatment For Rotary Kettle Type Pelletizing Equipment

Mechanical seeding is an effective way to save labor and improve efficiency,but it has high requirements on seed fluidity and seed specifications,resulting in some small-sized shaped seeds cannot be mechanically seeded,thus causing waste and low seeding efficiency.A JKR surface energy based rotary kettle model was developed in response to the current problems of flat,light and irregular chili seeds as well as the lack of equipment for pelletizing and the low quality of the finished pelletized seeds.By adjusting the rotating speed,inclination angle and volume content of binder of the rotary kettle,the processing parameters of chili seed pelleting were optimized to improve the quality of pelleting seeds.In order to accurately calculate the parameters involved in the discrete element numerical simulation of chili seeds,the parameters used in the simulation were calibrated in combination with physical experiments and numerical simulations.The essential parameters of chili seeds such as triaxial size,density,Poisson’s ratio,etc.,as well as contact parameters such as friction coefficient and restitution coefficient,were determined through basic physical experiments to provide reliability for the parameters involved in discrete element simulation experiments.In the EDEM software,the"Hertz-Mindlin with JKR"viscosity model was selected for the angle of repose test of the chili seeds.The Plackett-Burman test was chosen to filter out the parameters with great influence by using the angle of repose as the response value.The steepest climb test was then employed to determine the optimal range of significant parameters.Finally,the response surface method(Box-Behnken)was applied to analyze the variance of the quadratic polynomial of the regression model between the angle of repose,the relative error and the three significant parameters,and to find the optimal parameter combination.The obtained optimal parameter combination was found to be 0.75 for the rolling friction coefficient between the chili seeds,0.31 j/m~2 for the JKR surface energy and 0.60 for the rolling friction coefficient between the chili seeds and the steel plate.By using the optimal parameter combination to simulate the test,the average angle of repose was 28.10°,and the relative error was 2.16%.Based on the discrete element EDEM simulation software,the influence of the movement trajectory of chili population on the inclination angle,rotation speed and surface energy of the turret was discussed.The simulation results showed that the best movement trajectory of the chili population was achieved at a rotational speed of 50 r/min,an inclination angle of 20°and a surface energy of 0.8 j/m~2.Using the existing pelletizing equipment,the orthogonal experiment of 3 factors and 5 levels was designed,with the rotating speed of the kettle,the inclination Angle of the kettle and the volume content of adhesive as factors,and the compressive strength,seed rate,single seed rate and pelletizing rate of chili seeds as indicators.The results showed that the volume content of adhesive had the greatest influence on compressive strength and single seed rate,the speed had the greatest influence on seed rate,and the angle had the greatest influence on pellet rate.The optimal combination of pelletizing processing parameters was 50 r/min for rotational speed,20°for inclination angle and 2.7 ml per 50 g of seeds for binder volume content.