三产品旋流分级筛透筛过程对内部流场的影响研究

发布时间：2018-05-05 02:10

本文选题：三产品旋流分级筛 + FLUENT　；参考：《中国矿业大学》2017年硕士论文

【摘要】：三产品旋流分级筛作为一种新型高效的细粒煤分级设备,具有十分重要的研究价值和应用前景。本文以三产品旋流分级筛内部液相流场作为研究内容,重点分析透筛过程对内部液相流场的影响,为后续研究提供一定的帮助。本文首先对三产品旋流分级筛的内部流场进行理论分析,目的是为了FLUENT仿真模拟选择合适的计算模型和边界条件。经过Solidworks建立流场模型、ICEM前处理、FLUENT仿真模拟,得到三产品旋流分级筛和水力分级旋流器内部的流场信息。本文利用物理模型做出的试验结果和流场模型做出的模拟结果进行三个产品的流量对比,从而验证流场模型所选择的RSM+VOF计算模型和边界条件的正确性。通过对比器壁开有筛网的三产品旋流分级筛和器壁无网的水力分级旋流器内部的流场信息发现,三产品旋流分级筛内部流场要比水力分级旋流器需要更长的时间来稳定,筛网透筛过程的存在导致在同一入料速度10m/s的条件下,三产品旋流分级筛的入口静压比水力分级旋流器的低了50.6%,内部流场的整体静压也比水力分级旋流器中的静压大幅降低,溢流口压力降由水力分级旋流器的48.6kpa降为了24.1kpa,三产品旋流分级筛锥段的最大切向速度已经不到1m/s,基本达不到离心分级的效果,锥段轴向零速包络面的范围比水力分级旋流器的小很多,即三产品旋流分级筛中的离心分级粒度比水力分级旋流器中的小。最后,通过改变筛网的高度来研究不同透筛过程强度下对内部流场的影响,分别选取了高径比为2.0和1.5条件下的三产品旋流分级筛模型进行模拟,得出了高径比为1.5时的三产品旋流分级筛内沿半径的静压梯度远高于高径比为2.0和2.5的静压梯度,非常接近水力分级旋流器中的静压梯度;其次,高径比为1.5的三产品旋流分级筛锥段内的最大切向速度是高径比2.0和2.5的3倍以上,数值上可以达到2.5-3.5m/s,而离心力是水力分级旋流器的0.575倍,在具有筛网存在的条件下,还能保证锥段的离心力场,从而使得三产品旋流分级筛的筛分分级和离心分级都得到了保障。本文的研究成果为进一步研究三产品旋流分级筛内部流场提供了一个新的视角,为三产品旋流分级筛结构优化和工艺调整提供理论指导。
[Abstract]:As a new type of high-efficient fine coal classification equipment, the three-product swirl classifier has very important research value and application prospect. In this paper, the internal liquid flow field of the three-product swirl sieve is taken as the research content, and the influence of the permeation process on the internal liquid flow field is analyzed, which provides some help for the further study. In this paper, the internal flow field of the three-product swirl sieve is theoretically analyzed in order to select the appropriate calculation model and boundary conditions for the FLUENT simulation. The flow field information of the three-product swirl sieve and hydrocyclone was obtained by simulation and simulation of Solidworks flow field model. In this paper, the experimental results of the physical model and the simulation results of the flow field model are used to compare the flow rate of the three products, so as to verify the correctness of the RSM VOF calculation model and the boundary conditions selected by the flow field model. By comparing the flow field information inside the three-product swirl classifier with sieve opening and the hydrocyclone with no screen on the wall, it is found that the internal flow field of the three-product swirl classifier needs longer time to be stable than that of the hydrocyclone. Under the condition of the same feed speed 10m/s, the inlet static pressure of the three-product swirl classifier is 50.6 lower than that of the hydraulic classifier, and the whole static pressure of the internal flow field is significantly lower than the hydrostatic pressure in the hydrocyclone. The pressure drop of the overflow port is reduced from 48.6kpa of the hydrocyclone to 24.1 kpa.The maximum tangential velocity of the cone section of the three-product swirl classifier is less than 1m / s, which can hardly achieve the effect of centrifugal classification. The range of the axial zero velocity envelope of the cone is much smaller than that of the hydrocyclone, that is, the centrifugal particle size in the three-product cyclone is smaller than that in the hydrocyclone. Finally, by changing the height of sieve mesh to study the influence of different intensity of permeation process on the internal flow field, the three-product swirl classifying sieve model with the ratio of height to diameter 2.0 and 1.5 is selected to simulate, respectively. The static pressure gradient along the radius of the three-product swirl classifier is much higher than the hydrostatic gradient with the aspect ratio of 2.0 and 2.5, which is very close to the hydrostatic gradient in the hydrocyclone. The maximum tangential velocity in the cone section of the three-product swirl classifier with aspect ratio of 1.5 is more than three times that of the ratio of height to diameter 2.0 and 2.5, and the numerical value can reach 2.5-3.5 m / s, while the centrifugal force is 0.575 times that of the hydrocyclone. The centrifugal force field of the cone section can also be guaranteed, so that the sieve and centrifugal classification of the three-product swirl sieve can be guaranteed. The research results in this paper provide a new angle of view for further study on the internal flow field of three-product swirl classifier, and provide theoretical guidance for the optimization of structure and process adjustment of three-product swirl classifier.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD452

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