选煤厂产品煤自动采样系统应用与优化

为了提高自动采样系统的采样精度,分析了斜沟选煤厂自动采样系统存在的问题,并提出改造措施,最后对自动采样系统进行偏差分析,验证改造效果。结果表明,自动采样系统存在故障率高、卡堵严重、系统偏差大等问题,通过调整采样系统初采刮煤板衬垫和输送带架托辊位置,加强设备维护,调节采样系统中二级采样下料口处挡煤板为倾斜45°的导流板,调节输送带中部平煤高度和输送带运转速度等措施对选煤厂自动采样系统进行改造。改造后自动采样系统总均方差为0.313,提高了采集煤样的代表性。

大容量搅拌式气透干燥机的研发及性能试验验证

为了减少破碎、缩分等煤样制备关键环节的黏堵与残留,煤样干燥是最有效的解决办法之一。针对目前煤样制备系统中煤样干燥效率低、损失大、干燥量小等问题,开发了1种大容量搅拌式气透干燥机。采用螺旋式叶片、蜂窝状气孔、粉料回收系统等设计,将干燥热空气从螺旋式叶片的蜂窝孔中喷出,使煤样与干燥空气进行充分热交换,从而实现煤样的快速干燥。同时粉料回收系统将残气中携带的粉样重新送回到干燥腔内,大幅减少煤样损失。为了验证该干燥机的效率、煤样损失以及灰分指标,对其开展了试验研究。结果表明:该干燥机的煤样损失率为0.24%,相对于国标规定的恒温干燥箱法,该干燥机的干燥效率更高;对于灰分指标,该设备方法可完全替代国标方法。

A general solution and approximation for the diffusion of gas in a spherical coal sample

The square root relationship of gas release in the early stage of desorption is widely used to provide a simple and fast estimation of the lost gas in coal mines. However, questions arise as to how the relationship was theoretically derived, what are the assumptions and applicable conditions and how large the error will be. In this paper, the analytical solutions of gas concentration and fractional gas loss for the diffusion of gas in a spherical coal sample were given with detailed mathematical derivations based on the diffusion equation. The analytical solutions were approximated in case of small values of time and the error analyses associated with the approximation were also undertaken. The results indicate that the square root relationship of gas release is the first term of the approximation, and care must be taken in using the square root relationship as a significant error might be introduced with increase in the lost time and decrease in effective diameter of a spherical coal sample.