筒式冷却机颗粒物料运动规律的模拟仿真与研究

发布时间：2018-04-10 03:08

本文选题：筒式冷却机　切入点：离散元法　出处：《武汉理工大学》2014年硕士论文

【摘要】：筒式冷却机按筒体形式分为单筒冷却机和多筒冷却机，冷却形式主要包括筒体内部气体介质对流的直接冷却和筒体外部喷射水雾的间接冷却。针对后者的冷却形式，国内外大多数行业都是采用冷却水间接喷淋筒体外壁，甚至是冷却水直接浸泡筒体的冷却方式来达到冷却效果。然而，通过研究国外先进的喷雾冷却设备，可以看出，和现有的喷水冷却设备相比，在相同的产量要求下，采用喷雾冷却技术的冷却设备冷却效率高、占地小、成本低、能源动力消耗小，更加节能环保。在能源日益紧缺，环境保护越来越受到重视的背景下，喷雾冷却技术在工业领域特别是在机械和建材行业有着广阔的应用前景。还原铁喷雾回转筒式冷却机就是一种将冷却水雾化，直接喷射到筒体外壁，从而间接冷却筒体内部物料的新型节能环保冷却设备。由于该筒式冷却机采用间接冷却的冷却形式，所以冷却机内颗粒物料的运动规律和特性对冷却机设备设计及冷却效率的提高都有着重要影响。颗粒物料在筒体内的流动过程可看作是离散固体的运动过程，为了计算分析其运动规律和分布特性，有两种分析方法：一种是连续介质力学法，但连续介质机理过分依赖简化的、规定性质的本构方程，忽略了颗粒个体的性质。另一种是不连续介质力学方法，比如离散元法（Distinct Element Method）。离散元法是把整个系统看作由一系列独立的颗粒单元组成，每个单元本身具有一定的几何和物理特性。PFC（Particle Flow Code）软件就是利用显示差分算法和离散元理论开发的微/细观力学程序，从微观结构角度研究介质的基本力学特性和行为，并认为给定介质在不同应力条件下的基本特征主要取决于粒子之间接触状态的变化，适用于研究颗粒的流动问题。本文针对新型筒式冷却机——还原铁喷雾回转筒式冷却机的工况条件，模拟了颗粒物料在筒式冷却机内的运动规律及颗粒间的相互作用。运用颗粒流理论和颗粒流分析平台，，使用PFC中的内置FISH语言编制程序，建立了筒式冷却机的横截面模型，将颗粒处理为二维圆盘，利用WALL命令建立回转筒体壁面并使其以一定角速度转动，从而实现了对冷却机内颗粒物料运动规律的动态模拟仿真。模拟中主要针对筒体转速和筒体内部扬料板数量等设备相关参数以及颗粒粒径、物料填充率等物料相关参数的不同，将其与工况状态下的颗粒运动分布规律进行了对比分析研究。通过研究，得到了颗粒物料在筒体横截面内的动态运行效果，以及单个颗粒在筒体横截面上的运动轨迹曲线。本文研究得出了单个颗粒的运动轨迹形状、工况条件下该设备内的物料休止角以及各因素对物料运动规律的影响。本文对于以颗粒物料为介质进行作业的回转筒式设备（圆筒冷却机、圆筒混合机、转筒干燥机和回转窑等）内物料运动规律的研究具有一定的参考价值。
[Abstract]:The cylinder cooler can be divided into single tube cooler and multi tube cooler according to the form of cylinder. The cooling forms mainly include the direct cooling of gas convection inside the cylinder and the indirect cooling of spray water mist outside the cylinder.In view of the cooling form of the latter, most industries at home and abroad use the cooling water indirect spray tube outside the wall, even the cooling water directly immersed in the tube to achieve cooling effect.However, by studying the advanced spray cooling equipment abroad, it can be seen that, compared with the existing spray cooling equipment, the cooling equipment with spray cooling technology has higher cooling efficiency, less land occupation and lower cost under the same output requirements.Energy consumption is small, more energy conservation and environmental protection.In the background of energy shortage and environmental protection, spray cooling technology has a broad application prospect in industrial field, especially in machinery and building materials industry.The reductive iron spray rotary cylinder cooler is a new type of energy saving and environmental protection cooling equipment which atomizes the cooling water directly into the outer wall of the cylinder and indirectly cools the inner materials of the cylinder.Due to the indirect cooling of the cooler, the movement and characteristics of the particles in the cooler have an important effect on the design of the cooler equipment and the improvement of the cooling efficiency.The flow process of granular material in the cylinder can be regarded as the motion process of discrete solid. In order to calculate and analyze its motion law and distribution characteristic, there are two analytical methods: one is continuum medium mechanics method.However, the continuum mechanism relies too much on the simplified constitutive equations with specified properties and neglects the properties of the particles.The other is discontinuous Element method, such as discrete element method.The discrete element method regards the whole system as a series of independent particle units. Each unit has certain geometric and physical properties. The software PFCU Particle Flow Code is a micro / meso-mechanics program developed by using the display difference algorithm and discrete element theory.The basic mechanical properties and behaviors of the medium are studied from the point of view of microstructure, and it is considered that the basic characteristics of a given medium under different stress conditions mainly depend on the change of the contact state between particles, and are suitable for studying the flow problem of particles.In this paper, according to the working conditions of a new type of cylinder cooler, the movement law of particle material and the interaction between particles in the cylinder cooler are simulated.Based on the particle flow theory and particle flow analysis platform, the cross section model of the cylinder cooler is established by using the built-in FISH language in PFC. The particles are treated as two dimensional disks.The wall surface of the rotary cylinder was built by WALL command and rotated at a certain angular speed, so that the dynamic simulation of the motion law of the particle material in the cooler was realized.In the simulation, the parameters such as rotating speed of the cylinder and the quantity of the lifting plate inside the cylinder, as well as the particle size, the filling rate of the material and so on, are different.The distribution of particle motion is compared with that under working condition.The dynamic running effect of granular material in the cross section of the cylinder and the trajectory curve of a single particle in the cross section of the cylinder are obtained.In this paper, the trajectory shape of a single particle, the angle of repose of the material in the equipment and the influence of various factors on the moving law of the material are obtained.This paper has a certain reference value for the study of the movement law of the materials in the rotary drum type equipment (cylinder cooler, cylinder mixer, rotary dryer and rotary kiln, etc.) in which the particle material is used as the medium.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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