Study And Analysis Of Screening Performance And Parameter Optimization Of Pulverized Coal Sample Preparation Device

Coal resource is an important cornerstone of China's economic development,providing power for China's power,chemical,medical and other important industries.With the development of economy,especially in the past 30 years,China's demand for coal is increasing,which also brings serious environmental pollution and other problems.Due to the wide distribution and uneven quality of coal in China,in order to reduce environmental pollution and judge the quality of this batch of coal samples,it is necessary to detect its specific elements.In order to prepare representative coal samples,it is necessary to design related equipment for coal sample preparation.At present,most of the domestic pulverized coal sampling devices are large in volume,noisy in operation and lack of automation,which cannot meet the needs of enterprises at this stage.In this paper,a kind of portable pulverized coal sampling device is developed,which can classify the pulverized coal particles according to the different particle size,and pave the way for the follow-up work.Then,the movement state and screening accuracy of pulverized coal on the vibrating screen are studied and analyzed to further understand the influence of vibration parameters on its working performance,which provides important basis for the following device structure optimization and the improvement of screening theory.According to the market research,put forward the use requirements of the coal powder sample preparation device,and design the three-dimensional model of the device.The device mainly includes three parts: material screening device,hopper device and material collection device.The main part of the material screening device is the optimized linear vibrating screen.Through the analysis of the motion state of the vibrating screen,it is found that the main factors affecting the working performance are: the vibration frequency(the frequency of motor rotation),the vibration amplitude(the amplitude of the screen swinging in the specified direction)and the inclination angle(the angle between screen surface and horizontal surface).The movement of pulverized coal particles on the vibrating screen was simulated by discrete element method.In this paper,Hertz Mindlin with JKR cohesion(JKR)contact model is used to screen spherical and non-spherical particles.Set global variables to start simulation.In the data analysis,Taguchi orthogonal method is used,and the main effect curve of screening accuracy is taken as the index to find a group of vibration parameters with the best screening performance.The screening accuracy mainly includes three parts: average particle speed,screening efficiency and screening time.Through the research and analysis,it is found that the influence of each factor on the screening accuracy is the tilt angle>vibration amplitude>vibration frequency.The best vibration parameters are: vibration frequency is 14.2Hz,vibration amplitude is 3.6mm,and inclination angle is 14.4°.Set up the experimental platform of the coal powder sample preparation device,and set up the orthogonal table to carry out the vibration screening experiment.The optimal vibration parameters are as follows: the vibration frequency is 16 Hz,the vibration amplitude is 3mm,and the tilt angle is 14°,which is almost the same as the simulation results.It can be concluded that the discrete element method has a strong accuracy in dealing with particle vibration screening.The simulation optimization is carried out in the early stage of device manufacture,which provides reference for the application and expansion of DEM.Compared with the traditional control variable method,the Taguchi orthogonal analysis method in this paper greatly reduces the amount of experiment and calculation,and also reduces the interaction of various factors,which has a good application value.