煤粉秸杆类生物质颗粒气力输送最小起动速度的试验研究

论文总字数：25785字

摘 要

：本文以煤粉与秸秆的混合颗粒为主要研究对象，其中秸秆颗粒选取苏北的稻草秸秆，并用玻璃珠代替煤粉颗粒。根据实验所需的要求，确定好实验装置的参数，选取好相应的实验设备。在实验室搭建相应的气力输送系统后，借助固体颗粒的起动机理，对混合颗粒的最小起动速度进行试验研究。实验利用高速摄影设备对起动过程的视频进行采集，然后对得到的视频进行预处理，得到粒子层的背景轮廓。然后进行背景分离，对所得运动区域内的粒子数目进行统计，并通过逻辑运算就可以确定其起动速度。同时每次实验测量粒子层损失的质量，画出它与输送风速之间的关系曲线，利用质量损失法通过简单的外推，即可得到起动速度。两种测量方法可相互验证。为了探究秸秆粒径、玻璃珠粒径以及质量混合比对于起动速度的影响，实验采用了控制变量法。得到了以下实验结果:混合颗粒的起动速度随着秸秆颗粒质量配比的增加而逐渐减小;随着掺入的秸秆粒径的增加而减小，且随着秸秆粒径的增大减小的趋势越快;随着玻璃珠粒径的增加逐渐呈现先减小后增大的形式。产生这样的变化规律主要与两种颗粒密度的差异和玻璃珠颗粒之间的相互作用力有关。分析、总结产生这些变换规律，为预测煤粉/秸秆类生物质混合颗粒的气力输送系统的输送速度提供相应的依据。

关键字：气力输送 秸秆颗粒 煤粉 最小起动速度 图像处理法 质量损失法

A study on the pickup velocity of the particles of pulverized

coal and straw mixture in pneumatic conveying system

03012116 ZHOU GUANGCAN

Supervised by LU YONG

Abstract: In this paper, the main research object is the mixture of pulverized coal and straw particles which are from the south of JIANAGSU Province. Considering the availability in the laboratory, we choose glass beads to replace pulverized coal. Firstly, it is necessary to build a pneumatic conveying system by choosing appropriate experimental equipment to ensure this system works securely, efficiently and stably. Subsequently, based on the pick up mechanism of particles, the minimum pickup velocity of the mixed particles could be studied in this system. In this experiment, high-speed camera is used to capture the video of whole process, after which the background profile could be separated by applying some related image processing techniques. Thus, in the remained area, the number of particles can be calculated, hence making it possible to get the minimum pickup velocity. Also after plotting the weight reduction of the particles layer as a function of operating gas velocity, it is possible to get the pickup velocity by extrapolating these experimental curves. In order to explore the effect of particle size, particle size and mass ratio on the pickup velocity, the control variables method is adopted in this experiment.

Experimental results are obtained: the pickup velocity of the mixed particles decreases with the increase of mass ratio of straw particles and straw particle size. And with glass bead diameter increased, the pick up velocity gradually decreases, but later show a upward trend. The reasons of these experimental results, gained in this experiment, not only are related to the difference between glass beads and straw particles, but contribute to the interaction forces among glass beads. Finally, analyzing and summarizing these reasons could provide a theoretical basis for the prediction of the pick up velocity in a conveying system.

KEY WORDS: pulverized coal, straw particles, pneumatic transmission, pick up velocity, image processing, weight reduction

目 录

摘要 I

Abstract II

变量注释表 1

第一章 绪论 2

1.1 生物质能源开发的目的与意义 2

1.2 气力输送的特点与研究现状 2

1.2.1 气力输送的原理及气固两相流的特点 2

1.2.2 气力输送的分类及特点 3

1.2.3 单种颗粒起动速度的研究 3

1.3 本文的研究意义与研究内容 4

第二章 实验装置的设计与搭建 6

2.1 实验原理 6

2.1.1 最小输送速度 6

2.1.2 起动机理的受力分析 7

2.2 实验装置的设计与参数的选取 8

2.2.1 实验物料 9

2.2.2 送风参数的选择 10

2.2.3 测量与采集控制系统 11

2.2.4 除尘系统与其它实验设备 12

第三章 煤粉/秸秆等生物质颗粒最小起动速度的实验研究 14

3.1 实验的主要内容 14

3.2 实验的测量方法 14

3.3 图像处理法 15

3.2.1 图像预处理 15

3.3.2图像处理法得起动速度 16

3.4 质量损失法 18

3.4.1 质量损失法的原理 18

3.4.2 质量损失的处理过程 18

第四章 实验结果与分析 20

4.1 质量比的影响 20

4.2 秸秆粒径的影响 22

4.3 玻璃珠粒径的影响 23

第五章 总结 25

致 谢 26

参考文献(References) 27

变量注释表

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