循环流化床中颗粒振荡循环现象的实验研究

doi:10.11949/j.issn.0438-1157.20150647

化工学报 ›› 2015, Vol. 66 ›› Issue (8): 2929-2939.DOI: 10.11949/j.issn.0438-1157.20150647

循环流化床中颗粒振荡循环现象的实验研究

訾灿, 黄正梁, 廖祖维, 蒋斌波, 王靖岱, 阳永荣

浙江大学化学工程与生物工程学院化学工程联合国家重点实验室, 浙江杭州 310027

收稿日期:2015-05-21 修回日期:2015-05-25 出版日期:2015-08-05 发布日期:2015-08-05
通讯作者: 黄正梁
基金资助:
国家自然科学基金项目(21236007)。

Experimental research on solids oscillation circulation behavior in circulating fluidized bed

ZI Can, HUANG Zhengliang, LIAO Zuwei, JIANG Binbo, WANG Jingdai, YANG Yongrong

College of Chemical and Biological Engineering, State Key Laboratory of Chemical Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China

Received:2015-05-21 Revised:2015-05-25 Online:2015-08-05 Published:2015-08-05
Supported by:
supported by the National Natural Science Foundation of China (21236007).

摘要/Abstract

摘要：

颗粒的循环特性是循环流化床研究的重点及热点之一,在建立颗粒循环时,颗粒循环由非稳态向稳态过渡。本文在循环流化床实验装置中,采用摄像法和压力检测法研究了不稳定颗粒循环条件下颗粒流动结构和各段压降的变化情况。首次发现了不稳定颗粒循环状态下的颗粒振荡循环现象及其具有的两个特征:下降段、提升段气固流动结构呈周期性变化;下降段压降p_d和提升段压降p_r周期性波动且p_d>p_r和p_d<p_r交替出现。进一步对颗粒振荡循环过程进行受力分析,建立了颗粒振荡周期的计算公式。研究还发现在颗粒藏量一定的条件下,循环气流量或颗粒循环段阀门开度大于某一临界值时才能诱发颗粒振荡循环;颗粒振荡循环周期随着循环气流量的增大而增大,与阀门开度无关。研究结果为动态颗粒循环建立过程的研究奠定了基础,有助于快速地建立颗粒的稳定循环。

关键词: 循环流化床, 颗粒振荡循环, 流动结构, 压降

Abstract:

During the process of solids circulation establishment in circulating fluidized beds (CFBs), the solids circulation goes through a transition from an unstable state to a stable one. In this work, the stability of solids circulation in a CFB with limited bed inventory is studied by using a pressure transducer and a digital camera. The work reveals an interesting phenomenon, termed as oscillation circulation behavior of solids transportation between the riser and the downer through a solid control valve. Two important features are noted from the experimental results. Firstly, the gas-solid flow pattern in the riser and the downer is in transition between various fluidization regimes. Secondly, the pressure drop of the riser and the downer fluctuates periodically alternating between p_d>p_r and p_d<p_r. The calculation model of oscillation cycle is deduced by force analysis of oscillation process. Further study shows that solids oscillation behavior is controlled by the gas flow and valve opening. With a constant bed inventory, the oscillatory behavior is only initiated by the critical gas flow or valve opening. The oscillation cycle decreases with the decrease in gas flow but remains constant with varying solid control valve opening. The amount of solid transfer decreases with the decrease in gas flow and valve opening, while the pressure drop fluctuation decreases.

Key words: circulating fluidized bed, oscillation circulation, flow pattern, pressure drop

中图分类号:

TQ021.1

訾灿, 黄正梁, 廖祖维, 蒋斌波, 王靖岱, 阳永荣. 循环流化床中颗粒振荡循环现象的实验研究[J]. 化工学报, 2015, 66(8): 2929-2939.

ZI Can, HUANG Zhengliang, LIAO Zuwei, JIANG Binbo, WANG Jingdai, YANG Yongrong. Experimental research on solids oscillation circulation behavior in circulating fluidized bed[J]. CIESC Journal, 2015, 66(8): 2929-2939.

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循环流化床中颗粒振荡循环现象的实验研究

Experimental research on solids oscillation circulation behavior in circulating fluidized bed

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