论文总字数：23800字

摘 要

粉体工业中静电产生是一个非常普遍的现象，由于粉体与器壁以及粉体颗粒与颗粒之间的碰撞、摩擦，粉体不可避免地产生静电。在输送管道的荷电粉体会造成粉体的团聚、堵塞甚至发生燃爆；当荷电粉体输送到仓储设备中，静电不断累积，电压可高达数万伏，可能会引起粉体放电，当空气中存在粉尘或者易燃气体时就会有静电燃爆的危险。

粉体输送、流化过程中，影响静电产生的因素很多。颗粒的物性、流化操作参数及环境条件等都对流化过程中的带电有很大影响。目前，对于上述因素对颗粒荷电特性的影响仍未有统一的认识，许多研究呈现出不同的结论。

本实验旨在探究多颗粒流化的颗粒静电特性。搭建多颗粒流化实验系统，以线性低密度聚乙烯为实验原料，分别探究流化时间、流化风速、颗粒掺混比例、颗粒粒径比、颗粒初始电荷量及物料量对颗粒流化荷电特性的影响。

对流化时间的研究表明存在饱和流化时间，使得颗粒的电荷量达到相对饱和状态。对流化风速的研究表明提高流化风速会促进流化过程中的颗粒荷电。对二元颗粒混合比例的研究表明当小颗粒的比例超过20wt%后，二元颗粒出现电荷分离现象，大颗粒整体带正电而小颗粒整体带负电。二元颗粒粒径差距越大电荷分离现象越明显，大颗粒整体带上更多的正电而小颗粒整体带上更多的负电。小颗粒初始电荷量减小时，流化过程中的荷电量增大；小颗粒初始电荷量增加时，流化过程中的荷电量减小，大颗粒整体带电趋势由正电向负电转变。对物料量的实验研究结果呈现大颗粒趋于带正电，小颗粒趋于带负电的双极带电特性，且随着物料量的增加双极带电特性更加明显。

关键词：颗粒，静电特性，流化，双极带电

Abstract

The generation of electrostatic charges is a very common phenomenon in the powder industry. Due to the collision and friction between the particles and particles and the wall, the powder inevitably produces electrostatic charge. The charged powder in the pipeline can cause the agglomeration, blockage and even the explosion of the powder. When the charged powder is transported to the storage equipment, the electrostatic charges accumulate continuously, the voltage can be as high as tens of volts, which may cause the powder discharge and electrostatic explosion when there is dust or flammable gas in the air.

In the process of transportation and fluidization, there are many factors that influence the generation of electrostatic charges. The physical properties of particles, fluidization operation parameters and environmental conditions have great influence on electrification in the fluidization process. At present, there is not a unified understanding of the influence of the above factors on the charging characteristics of particles.

This experiment is designed to explore the electrostatic characteristics of fluidized particles. Choosing linear low-density polyethylene as the experimental material, the effects of fluidization time, fluidization air velocity, particle mixing ratio, particle size, particle initial charge and particle mass on the charge characteristics of particle fluidized bed are investigated based on a multi-particle fluidization experiment system.

The study of the fluidization time shows that the saturation fluidization time makes the charge of particles relatively saturated. The study of fluidization air velocity indicates that increasing the fluidization velocity will promote the charging of particles in fluidization process. The study on the mixing ratio of two kinds of particles shows that when the proportion of small particles exceeds 20wt%, the charge separation phenomenon occurs, and the large particles are positively charged and the small particles are negatively charged. The larger the particle size difference of the two particles is, the more obvious the charge separation phenomenon is. The large particles are more positively charged and the small particles are more negatively charged. When the initial charge of the small particles decreases, the charge in fluidization process increases; The charge in fluidization decreases when the initial charge of the small particles increases and the overall charge trend of large particles changes from positive to negative electricity. The experimental results of the mass of particles show bipolar charged characteristics that the large particles tend to be positive and the small particles tend to be negatively charged, and the bipolar charged characteristics are more obvious with the increase of the mass of the particles.

Key words: particles, electrostatic characteristic, fluidization, bipolar charging

目 录

摘要 I

Abstract II

目录 III

第一章 绪论 1

1.1 研究背景 1

1.2 静电基础知识 1

1.2.1 静电起源 1

1.2.2 静电产生 1

1.2.3 静电危害 2

1.3 研究现状 3

1.3.1 多颗粒流化荷电特性影响因素 3

1.3.2 双极带电的研究 4

1.4 研究目标 4

第二章 实验原料、系统及方法 5

2.1 实验原料 5

2.2 实验系统 5

2.2.1 流化床 6

2.2.2 供气系统 6

2.2.3 颗粒风选系统 6

2.2.4 静电测量系统 7

2.3 实验方法 8

第三章 实验数据与分析 10

3.1 法拉第筒倾倒误差分析 10

3.2 流化时间对颗粒流化荷电的影响 11

3.3 流化风速对颗粒流化荷电的影响 12

3.4 颗粒掺混比例对颗粒流化荷电的影响 13

3.5 颗粒粒径比对颗粒流化荷电的影响 15

3.6 颗粒初始电荷量对颗粒流化荷电的影响 16

3.7 物料量对颗粒流化荷电的影响 18

第四章 结论与展望 20

4.1 结论 20

4.2 展望 20

致谢 22

参考文献 23

第一章 绪论

• 1. 研究背景

能源是人类社会赖以生存的物质基础。纵观人类社会发展的历史，人类社会的每一次重大进步都伴随着能源的更替。中国煤炭资源丰富而油气资源相对较为匮乏。目前中国能源的结构以煤炭资源为主，并将长期在一次能源中占主体地位^[1]。煤炭的利用效率低于石油和天然气，其对环境所造成的污染要大于石油和天然气。

剩余内容已隐藏，请支付后下载全文，论文总字数：23800字