用于粗煤泥脱水脱泥滚筒筛的研制及其性能试验研究

发布时间：2018-08-19 13:30

【摘要】：粗煤泥是在煤炭洗选加工过程中的一种伴生煤泥，这种煤泥粒度较小，大约在1mm左右，级别宽，颗粒形状复杂，表面积大，持水性强，水分含量高，且在选煤厂中大量存在，能否有效的对这部分煤泥脱水脱泥并实现回收具有可观的经济效益。近年来对粗煤泥独立实施分选已经成为一种既定工艺，但由于水力分选中粒度的影响，使得细粒物料的灰分总是大于粗粒物料，而现有的细粒筛分设备脱泥效果又不尽人意，导致粗煤泥精煤灰分偏高，亟需研究一种新型高效的粗煤泥分级脱水脱泥设备，提高粗煤泥的回收效果。文章将滚筒筛应用在粗煤泥回收过程中的脱水脱泥上，试制了一种适用于处理煤泥水的滚筒筛，并在筛筒内壁加设了螺旋导流叶片，而不是通过安装倾角来出料。该滚筒筛主要是采用过滤的原理，将物料通过给料装置给入到旋转的筛筒中，粗颗粒快速沉降到筛筒内壁，由于筛筒的转动带动内壁沉降下来的料层倾斜上移并翻滚，使上层悬浮液所受的料层阻力显著减小而快速透筛，未透筛的固体颗粒在重力和螺旋导流的推动作用下沿筛筒轴线方向出料。从而实现了滤液由筛缝流下，而料层由螺旋导流叶片轴向导出。使用该滚筒筛对粗煤泥进行分级试验，分别对操作参数（滚筒转速和入料流量）和入料性质（浓度和粒度）进行了相关试验研究，探究其在不同工况下的脱水脱泥规律。结果表明滚筒筛用于粗煤泥脱水分级具有良好的效果，筛上产物含水量可达到30%以下，分级效率可达到80%以上。滚筒筛的转速对脱水分级有很明显的影响，一般转速越高，脱水分级效果越好。入料流量也决定滚筒筛的转速，流量越大，所需的转速也越大。入料浓度对滚筒筛脱水和分级有不同的影响，，在入料浓度为30%时，脱水效果最差，低于或高于30%都会增强脱水效果；滚筒筛的分级效果是随着入料浓度的升高逐渐减小的。入料粒度中，难筛粒与阻碍粒含量越多，筛分效果越差。利用离散单元法软件EDEM对滚筒筛的筛分过程进行仿真试验研究。本次仿真试验重在研究不同转速下各粒级颗粒在滚筒筛内的运动状态及透筛情况，为了减少计算时间，对筛筒模型及颗粒模型进行了一定的简化。通过对仿真试验结果计算出的分级效率与实际试验分级效率对比，其分级规律基本一致，均随着转速的增高，分级效率增大。通过对颗粒在滚筒筛内的运动状态分析，得出不同粒级在滚筒筛内的运动状态不同：粒度越小，滑落运动状态时位置角越大，抛落运动状态时抛落角也越大，反之，则位置角和抛落角均越小；随着转速的增大，透筛面积会随着转动方向拓展，当转速为0.91Nc时，几乎在整个圆周方向均会透筛。通过对筛面上各粒级量的变化规律分析，得出粒级不同，螺旋导流叶片的推动作用不同，粒度越小，螺旋的推动作用越小，粒度越大，螺旋的推动作用则越大；通过对不同粒级颗粒透筛的分析，发现转速越高，透筛越快，其中粒级越小透筛越容易。文章从分别使用实际物料试验与EDEM仿真试验两个不同方面对试制的滚筒筛进行了研究，得出了一些有用的结论，为指导滚筒筛的设计与优化提供了一定的基础。
[Abstract]:Coarse slime is a kind of associated slime in the process of coal washing and dressing. The slime has small particle size, about 1 mm, wide grade, complex particle shape, large surface area, strong water holding capacity, high moisture content, and exists in a large number of coal preparation plants. Whether it can effectively dehydrate and desliming this part of slime and achieve recovery has considerable economic benefits. In recent years, independent separation of coarse slime has become an established process, but due to the influence of particle size in hydraulic separation, the ash content of fine material is always greater than that of coarse material, and the desliming effect of existing fine particle screening equipment is not satisfactory, resulting in high ash content of coarse slime concentrate. Therefore, it is urgent to study a new type of high efficiency coarse slime separation. The stage dewatering and desliming equipment improves the recovery effect of coarse slime.
In this paper, the roller screen is applied to the dewatering and desliming of coarse coal slurry recovery process, and a roller screen suitable for the treatment of coal slurry water is trial-manufactured, and a spiral guide vane is added to the inner wall of the screen cylinder, instead of discharging through the installation of inclination angle. In the middle, the coarse particles settle rapidly to the inner wall of the sieve barrel, and because the rotation of the sieve barrel drives the material layer to tilt upward and roll over, the resistance of the upper suspension layer is significantly reduced, and the solid particles which are not penetrated through the sieve can discharge along the axis of the sieve barrel under the impetus of gravity and spiral diversion. The sieve is sewn down by the seams, and the material layer is derived from the axial direction of the spiral guide vane.
The drum sieve was used to classify the coarse coal slime. The operation parameters (drum speed and feed flow) and the feed properties (concentration and particle size) were studied. The results showed that the drum sieve had a good effect on the dewatering and classification of the coarse coal slime and the water content of the product on the sieve was good. The rotational speed of the roller screen has a significant effect on the dehydration and classification. The higher the rotational speed, the better the dehydration and classification effect. The feed flow rate also determines the rotational speed of the roller screen. The greater the flow rate, the greater the rotational speed required. When the degree of dehydration is 30%, the dehydration effect is the worst, lower or higher than 30% will enhance the dehydration effect; the classification effect of roller screen is gradually reduced with the increase of feed concentration.
In this paper, the discrete element method (DEM) software EDEM is used to simulate the screening process of the roller screen. The simulation experiment focuses on the motion state of each particle in the roller screen at different rotational speeds and the penetration of the screen. In order to reduce the calculation time, the sieve cylinder model and the particle model are simplified. Comparing the calculated classification efficiency with the actual test classification efficiency, the classification law is basically the same, and the classification efficiency increases with the increase of rotational speed. Through the analysis of the motion state of particles in the roller screen, it is concluded that the motion state of different particle sizes in the roller screen is different: the smaller the particle size, the bigger the position angle in the sliding motion state, and the throwing motion. The bigger the throwing angle is, the smaller the position angle and throwing angle are; with the increase of rotational speed, the area of the screen will expand along the rotational direction, and when the rotational speed is 0.91Nc, it will penetrate the screen almost in the whole circumferential direction. Different, the smaller the particle size, the smaller the propelling role of the screw, the larger the particle size, the greater the propelling role of the screw; Through the analysis of different particle sieve, it is found that the higher the rotational speed, the faster the screen penetration, and the smaller the particle size, the easier the screen penetration.
This paper studies the trial-produced drum screen from two different aspects of actual material test and EDEM simulation test, and draws some useful conclusions, which provide a certain basis for guiding the design and optimization of drum screen.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD94

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