散状物料自由下落过程中粒径对产尘规律的影响研究

发布时间：2018-06-21 09:02

本文选题：自由下落 + 颗粒流　；参考：《西安建筑科技大学》2017年硕士论文

【摘要】：工业生产过程中,散状物料输送、转运是粉尘扩散的重要来源,研究该过程中的产尘机理对控制粉尘,确保生产安全、人员健康有着重要意义。为了研究散状物料的粒径对其自由下落过程中的粉尘逃逸的影响,选取工业生产中常用的二氧化硅物料进行分析。五组物料的中位径分别为:82.5μm、145.8μm、209.5μm、245.1μm、314.5μm。本文以粒径为重要变量之一,研究了在物料粒径、下落高度、出流口径三个变量作用下散状物料自由下落过程的产尘规律。分别以地面、水面为接触面,将总产尘分为下落时逃逸的一次尘和碰撞时产生的二次尘两部分。在用产尘率描述单位质量物料产尘量大小的基础上,引入粒度产尘率以描述物料某一粒径范围颗粒的成尘比例。基于此理论,本文以0-10μm颗粒为对象,探究了物料粒径、下落高度、出流口径对该粒径范围内产尘率、粒度产尘率的作用。并根据不同粒径颗粒对人体的危害程度,将0-10μm颗粒分为八个粒径范围,主要针对其中六个范围的产尘规律进行分析,得到物料粒径、下落高度、出流口径对不同粒径范围颗粒的粒度产尘率的影响,为日后降低通风系统能耗、提高除尘系统效率提供有效的理论依据。研究结果表明,对粒径范围0-10μm的颗粒,粒度产尘率随下落高度、物料中位径的增大而增大,随出流口径的增大而减小。较之二次粒度产尘率和总粒度产尘率,一次粒度产尘率受下落高度和物料中位径的影响最小。下落高度增大时,4.7-10μm颗粒占产尘的百分比增大,1.1-4.7μm颗粒占产尘的百分比减小。三个影响因素中,下落高度对一次粒度产尘率的影响最大,物料中位径与下落高度两个因素对二次粒度产尘率的影响基本相当。对比不同颗粒粒径范围的粒度产尘率可知,物料中位径对1.1-2.1μm颗粒的粒度产尘率影响较大,下落高度对3.3-4.7μm颗粒的粒度产尘率影响较大,而出流口径对9.0-10.0μm、5.8-9.0μm颗粒的粒度产尘率影响较大。本文分析了物料粒径、下落高度、出流口径对散状物料自由下落过程产尘的影响,并对三个因素与产尘率、粒度产尘率之间的关系做了深入分析,其结论对粉尘控制提供了一定的理论基础。
[Abstract]:In the process of industrial production, the transportation and transportation of bulk materials is an important source of dust diffusion. It is of great significance to study the mechanism of dust production in the process of controlling dust, ensuring the safety of production and the health of personnel. In order to study the influence of particle size on the dust escape in the free falling process, the silica materials commonly used in industrial production were selected for analysis. The median diameters of the five groups were: 1: 82.5 渭 m, 145.8 渭 m, 209.5 渭 m, 245.1 渭 m, 314.5 渭 m, respectively. Taking particle size as one of the important variables, this paper studies the law of dust production in the free falling process of loose material under the action of three variables: particle size, falling height and outlet diameter. Taking the surface and water surface as contact surfaces, the total dust production can be divided into two parts: the primary dust escaped when falling and the secondary dust produced during collision. On the basis of describing the dust production rate per unit mass material, the particle size dust production rate is introduced to describe the dust-forming ratio of a certain particle size range of the material. Based on this theory, the effects of particle size, falling height and outlet diameter on dust yield and particle size in the range of 0-10 渭 m particle size were investigated. According to the harm degree of different particle size to human body, the 0-10 渭 m particle is divided into eight particle size ranges. The dust production law of six range is analyzed, and the particle size and falling height are obtained. The influence of outlet diameter on the dust production rate of different particle size ranges provides an effective theoretical basis for reducing the energy consumption of ventilation system and improving the efficiency of dust removal system in the future. The results show that the dust yield increases with the drop height, the median diameter of the material increases, and decreases with the increase of the outlet diameter for the particles with the particle size ranging from 0 to 10 渭 m. Compared with the secondary particle size and the total particle size dust yield, the primary particle size dust yield is the least affected by the falling height and the median diameter of the material. When the falling height increases, the percentage of 4.7-10 渭 m particles in dust production increases and the percentage of 1.1-4.7 渭 m particles decreases. Among the three influencing factors, the falling height has the greatest influence on the dust yield of primary particle size, while the two factors of the medium diameter and falling height of the material have the same effect on the dust yield of the secondary particle size. Compared with the different particle size ranges, the median diameter of the particle has a great effect on the particle size of 1.1-2.1 渭 m, and the falling height has a great effect on the particle size of 3.3-4.7 渭 m. However, the diameter of outlet flow has a great effect on the particle size yield of 9.0-10.0 渭 m ~ (5.8 ~ 9.0 渭 m) particles. In this paper, the influence of particle size, falling height and outlet diameter on dust production in the free falling process of bulk materials is analyzed, and the relationship between three factors and dust production rate of particle size is deeply analyzed. The conclusion provides a theoretical basis for dust control.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X964

【参考文献】