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毕业论文-ECT电容成像技术测量异型截面气固流动特性，共100页，36508字
中文摘要
随着循环流化床（CFB）锅炉的大型化，原有的单分离器设计已无法满足要求。
采用多分离器布置结构，加剧了循环回路间的气固流动分配不均匀现象，严重影
响到锅炉的安全、经济运行。目前对此现象产生的原因还没有一个明确的解释，
因此，对多分离器结构 CFB 锅炉炉膛内气固流动规律进行在线测量，将有助于问
题的解决。
电容成像技术（ECT）具有全局实时、非侵入、安全廉价等特点，是一种有效
的气固流动规律的测量手段。鉴于锅炉炉膛截面均为长宽比较大的矩形，已有的
ECT 传感器多为圆形或正方形截面，无法直接适用，因此，本文针对 300mm×80mm
矩形截面开发了异型截面 8 电极 ECT 传感器。利用英国曼彻斯特大学（UMIST）
开发的 16 通道数据采集系统及线性反投影算法，在传感器极板布置、图像重建等
方面都进行了较大改进，选择的励激电压和励激频率分别为 17V、140Hz。测量结
果经过反复校验，证明其具有较高的准确性。
为了观测多循环回路 CFB 气固流动的不均匀现象，实验中搭建了双分离器
CFB 实验台，通过 ECT、光导纤维颗粒浓度分析仪、压差传感器等多种测量手段，
对实验台内的气固流动进行了测量。实验中改变表观气速和循环流率，首先在原
始炉膛条件下对提升管、分离器等部件的流动阻力特性进行了研究，提升管内的
流动均匀性较好。通过改变实验台内的边界条件，即增大提升管内壁面粗糙度、
布风不均匀程度等，探讨了不同条件对气固流动的影响。壁面粗糙度的差异可以
引起提升管局部的物料浓度分布变化，但对整个提升管内物料浓度分布影响不大。
布风不均对密相区气固流动的影响强烈，当布风不均匀严重到一定程度，对稀相
区气固流动也会产生影响。最后引入参数不均匀度 ψ，作为表征提升管内气固流动
均匀程度的指标。
关键词：电容成像技术；矩形截面；气固流动特性；循环流化床

ABSTRACT
With the increasing capacitance of circulating fluidized bed (CFB) boiler, the pa-
rallel cyclones are introduced in design, which causes serious non-uniform distribution
of gas-solid flow among the cyclones, which could be a great threat to safety and
economy of boiler operation. So far, there is still no clear explanation on this phenome-
non, so, much more detail measuring in the gas-solid flow pattern in CFB is required.
The electrical capacitance tomography (ECT) technology is of great value with the
features of online monitoring, non-invasive, safe and economical. Considering the
cross-section of CFB boiler furnace is normally rectangle with large ratio of length to
width, the existing ECT sensors with circular or square cross-sections cannot be applied
directly. With the 16-channel data acquisition system developed by UMIST and LBP
algorithm, a 8-electrode ECT system for the 300mm×80mm rectangle section was de-
veloped with significant improvement in the layout of the sensors and image recon-
struction. The excitation voltage and frequency were optimized as 17V and 140Hz re-
spectively. The ECT sensor was proved to be accurate with adjustment.
A cold-state CFB test rig with double cyclones was built to measure the
non-uniform gas-solid flow. ECT, optical fiber probe (OFP) and differential pressure
transducers were employed together to measure the behavior of gas solid flow in the
riser. Firstly, the flow resistance characteristics of CFB components were studied in the
original riser under different superficial gas velocities and solid circulating flow rates.
And then, the boundary conditions of the rest rig including the roughness of the riser`s
inner wall and the degree of uniformity of air distribution were changed to study the in-
fluence on the uniform distribution of gas solid flow in the riser. The roughness could
only change the local solid concentration rather than the whole riser, while, the
non-uniform air distribution intensively affected the gas-solid flow in the dense region
as well as the dilute region in extreme case. Also, a parameter of ψ was introduced in to
evaluate the degree of uniformity of gas-solid flow in the riser.
Keywords: ECT; Rectangle cross-section; Gas-solid Flow; CFB

目录
第 1 章
引言..... 1
1.1 循环流化床（CFB）锅炉简介 .... 1
1.1.1 CFB锅炉技术及发展现状. 1
1.1.2 CFB锅炉的大型化. 2
1.1.3 CFB锅炉大型化带来的技术难点. 3
1.2 循环回路气固流动特性.... 4
1.3 本文的研究内容.... 5
第 2 章
针对矩形截面的ECT系统开发与校验 ... 7
2.1 ECT技术简介 ... 7
2.1.1 ECT技术发展历史. 7
2.1.2 ECT技术基本原理. 7
2.2 ECT系统的开发 ..... 8
2.2.1 矩形截面ECT系统开发的难点.... 9
2.2.2 ECT传感器极板布置... 9
2.2.3 数据采集系统 11
2.2.4 图像重建 . 13
2.3 ECT系统的初步校验结果 ..... 16
第 3 章
CFB冷态实验系统 ... 18
3.1 实验台总体介绍.. 18
3.2 测量系统.. 19
3.2.1 压差传感器 ... 19
3.2.2 光导纤维颗粒浓度分析仪 ... 22
3.2.3 流量计 ..... 23
3. 3 床料特性. 23
3.4 其他设备及措施.. 25
3.4.1 防静电措施 ... 25
3.4.2 巡查机制 . 25
第 4 章
实验结果及分析. 26
4.1 冷态实验综述 26
4.1.1 定态理论 . 26
4.2.2 实验工况选取 ..... 26
4.2 原始炉膛测量 27
4.2.1 流态观察 . 27
4.2.2 回路各部件阻力特性 ..... 28
4.2.3 截面颗粒浓度分析 ... 33
4.3 壁面粗糙度对气固流动的影响.. 37
4.4 布风均匀性对气固流动的影响.. 39
4.5 不均匀度Ψ ..... 42
第 5 章
结论与展望... 43
5.1 实验结论.. 43
5.2 全文展望.. 43
插图索引 45
表格索引 47
参考文献 48
致 谢 51
声 明 52
附录A 外文文献翻译 ... 53
附录B 矩形截面单激励LBP重建算法Matlab程序代码 ... 90
在学期间参加课题的研究成果 92