Kinematics of elastic screen surface and elimination mechanism of plugging during dry deep screening of moist coal

摘要

The vibrating screens with elastic screen surface (EVS) have been widely used for cleaning moist coal due to their good performance. In this work, the kinematics and spatial behaviors of a novel elastic screen surface, and the screening behavior of particles were investigated using dynamic simulation and image analysis system to reveal the elimination mechanism of plugging during dry deep screening of moist coal. Furthermore, the effect of technological parameters on the performance of elastic deep screening was studied using single factor test method. The results indicated that the average vibration intensities of elastic screen rod and tube were significantly larger than 20 because of the collisions, which promoted the loosening of material. The frequency-domain of the elastic screen surface contained the fundamental frequency of the covering film, which resulted in the resonance and eventual breaking down of the covering film. The change in the spatial position of adjacent elastic screen surface and their own deformation led to the periodic fluctuation of screen aperture. Besides, the spatial rotation of the screen tube exhibited shear effect on the covering film, the adherent and the near-aperture particles, whereas the direction of spatial force was random, therefore, the rupture of the covering film and the adherent particles was promoted. In addition, with the increase of amplitude and feed rate, the screening efficiency first increased and then decreased, while with the increase of the speed of excitation motor and screen length, the screening efficiency gradually increased. When the values of amplitude, excitation motor speed, screen length and feed rate were 43 mm, 1000 r/min, 1200 mm and 1.5 kg/s respectively, the screening efficiency of Li Jiahao and Wan Li coal samples was >86%. (C) 2019 Elsevier B.V. All rights reserved.