摘要
根据动筛跳汰分选过程的特点 ,分析了动筛下降期颗粒沉降规律 ,讨论了机械驱动装置产生的正弦速度曲线和液压驱动装置产生的梯形速度曲线特征 ,推导了床面纵向各点动力学参数变化规律 ,提出了床面各点上颗粒脱离筛面实现床层松散的通用条件 ,计算了两种床面运动曲线下不同密度颗粒在床层不同位置的脱离点 .发现梯形波曲线驱动时筛面各点加速度远大于高密度颗粒沉降加速度 ,筛面各点物料均能脱离筛面 ,床层有足够的松散空间和时间且移动速度快、处理量大、分选精度高、适应性强 ;正弦曲线驱动时 ,在选煤工艺要求的频率、振幅条件下 ,排料端的高密度颗粒难以完全脱离筛面或脱离床面的时间短 ,矸石层的移动只能靠纵向压力梯度 ,移动速度慢 ,通过量仅为梯形波曲线的 1/ 2～ 1/ 3,导致处理量小 ,而在相同处理量时分选精度低 ,矸石带煤量较高 .
According to characteristics of separation process of movable bed jig ,analysis and study are made on its following aspects: law of particles settlement during the suction stroke ;characteristics of the sine velocity curve and trapezoidal speed curve produced respectively by mechanical and hydraulic driving units ;and the variation law of dynamic parameters at individual points of the bed in the longitudinal direction.The author also proposes in the paper: the general conditions for the particles at different points of bed to leave the screen plate for loosening the bed ;and the method for calculating the points at which the particles with different densities at different positions of the bed to leave the screen plate.It has been found that ,with the trapezoidal curve driving unit ,the acceleration of particles at different bed points is far greater than the settling acceleration of the high density particles ,making it possible for all the particles at different bed points to go upward from the screen plate.This provides therefore ample space and time for the jig bed to become mobile.Because of the faster motion speed of bed ,the jig has ,in this case ,a higher capacity ,separating accuracy and adaptability.Whereas with the sine curve driving unit ,under the specified frequency and amplitude conditions as required by the separating process ,the high density particles at the discharge end fail to go upward and the refuse layer is allowed to move only under the effect of pressure gradient in the longitudinal direction.Due to slow bed motion ,the throughput is found to be only 1/2～1/3 of that in the former case ,resulting in reduction of the jigs capacity ,lower separating precision at identical capacity and higher loss of coal in refuse.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2000年第6期649-654,共6页
Journal of China Coal Society
