湿煤粉在转运站中流动情况的离散元仿真研究

发布时间：2018-04-14 17:29

本文选题：转运站 + 粘性物料　；参考：《湘潭大学》2017年硕士论文

【摘要】：转运站是现代散状物料输送设备中的重要组成部分。在转运过程中物料从头部辊筒进行抛料,通过头罩的导流作用使其进入落料管内,然后顺着落料管管壁落入下行皮带被运送到指定位置。因此,头罩内的结构与落料管设计的好坏直接影响着物料转送的效率与转运站的使用寿命。国内外学者在对于转运过程的研究时,通常忽略了物料含有一定水分,从而未考虑其具有一定的粘性,而在实际工程中物料的粘性对于转运过程影响是巨大的。因此,有必要从理论计算、实验研究和数值仿真等相结合的角度对粘性物料在转运过程中的影响进行研究,本文从以下几个方面开展工作:(1)一般粘性物料的粒径都在微米级别,颗粒间的粘结力大于其重力,因此,在研究转运过程中粘性颗粒间的相互作用力时,必须考虑颗粒间的粘结力。本文首先介绍了经典弹性模型以及JKR模型、液桥模型,分析了它们的适用范围,在此基础上以湿煤粉作为粘性物料研究对象,提出适用于湿煤粉颗粒的接触模型,采用API建立EDEM中的接触计算模型。(2)通过直剪试验测试得到湿煤粉颗粒间的内摩擦系数,通过斜板实验测试得到湿煤粉颗粒与皮带及钢板间的滑动角,采用电热恒温干燥箱测试了实验样品的含水率,并且通过塌落实验校准了湿煤粉颗粒间的粘性参数。(3)通过建立简化的抛料模型,分析了湿煤粉颗粒间粘性对于抛料过程的影响,并且计算了在考虑粘性的情况下物料的卸料轨迹,与仿真结果进行了对比。在此基础上分析了转运站头罩内挡板的形状。(4)建立了转运站落料管的简化模型,利用前面所确立的湿煤粉DEM微观接触模型以及宏观接触参数,进行湿煤粉在落料管中转运过程仿真。确定其它参数不变,分别改变上行皮带的速度、喂料速度、物料粘性等参数,然后分析了各个参数在转运过程中对于落料管堵塞行为的影响,统计物料流出落料管时的速度预测其对于下行皮带的冲击影响。
[Abstract]:Transfer station is an important part of modern bulk material transportation equipment.In the process of transfer, the material is thrown from the head roller, and through the flow guide action of the hood, the material enters the drop pipe, and then falls down the tube wall and is transported to the designated position.Therefore, the structure of the hood and the design of the discharge pipe directly affect the efficiency of material transfer and the service life of the transfer station.In the research of the transfer process, scholars at home and abroad usually ignore the fact that the material contains a certain amount of water, so it is not considered that the material has a certain viscosity. However, in practical engineering, the viscosity of the material has a great impact on the transfer process.Therefore, it is necessary to study the influence of viscous materials on the transport process from the angle of theoretical calculation, experimental research and numerical simulation.The adhesion between particles is greater than its gravity. Therefore, in studying the interaction between viscous particles in the transport process, the adhesion between particles must be taken into account.In this paper, the classical elastic model, JKR model and liquid bridge model are introduced, and their application range is analyzed. On the basis of this, a contact model suitable for wet pulverized coal particles is put forward, based on which wet coal powder is used as the object of study on viscous materials.The contact calculation model in EDEM was established by API. (2) the internal friction coefficient between wet pulverized coal particles was obtained by direct shear test, and the slip angle between wet pulverized coal particle and belt and steel plate was obtained by inclined plate test.The moisture content of the experimental sample was measured by electrothermal constant temperature drying box, and the viscosity parameter between wet coal particles was calibrated by collapsing experiment. The effect of viscosity between wet coal particles on the process of material throwing was analyzed by establishing a simplified model of throwing material.The unloading trajectory of the material considering viscosity is calculated and compared with the simulation results.On this basis, the shape of the inner baffle of the hood of the transfer station is analyzed. The simplified model of the unloading pipe of the transfer station is established. The microscopic contact model of wet pulverized coal (DEM) and the macroscopic contact parameters are used.The transfer process of wet pulverized coal in blanking tube was simulated.Other parameters are determined to change the speed of the uplink belt, feeding speed, material viscosity and so on. Then, the influence of each parameter on the clogging behavior of the blanking pipe is analyzed in the process of transportation.The impact of the material on the down belt is predicted by calculating the velocity of the material flowing out of the blanking pipe.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD50;TP391.9

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