脉冲气流对烯烃流化床气泡特性的影响

doi:10.16085/j.issn.1000-6613.2021-1226

摘要/Abstract

摘要：

流化床具有良好的传热传质效率，因此广泛应用于煤粉燃烧、气力输送等场合。但是流化床在工作过程中会产生一定的恶性流动，脉冲的振动能量可以有效地提高流化床的传热系数，减少恶性流动现象发生。本文设计、搭建了烯烃流化床实验平台，通入混合脉冲气流。通过改变脉冲气流的相关参数，对静电信号进行功率谱密度函数分析。并基于静电信号估算气泡尺寸，从而获得流化床内气泡行为的变化。实验结果表明，脉冲气流的加入对气泡尺寸有一定的影响。随着脉冲频率的增加，气泡尺寸呈现先减小后增大的趋势，在脉冲频率为0.5Hz左右时气泡尺寸最小。脉冲气流加入后使得气泡尺寸减小，提高了颗粒流化效果，因此烯烃流化床内流化结束后的团聚颗粒质量明显降低。

关键词: 两相流, 流化床, 脉冲气流, 气泡, 流动, 团聚

Abstract:

The fluidized bed has good heat and mass transfer efficiency, which is widely used in pulverized coal combustion, pneumatic conveying and other occasions. However, the fluidized bed will produce a certain vicious flow during the working process. Pulse vibration energy can effectively improve the heat transfer co-efficiency of the fluidized bed and reduce the occurrence of vicious flow. Therefore, an olefin fluidized bed experimental platform was designed and built, and a mixed pulsed gas flow was introduced. The bubble behavior was obtained by changing the relevant parameters of the pulsed airflow to analyze the power spectral density function of the electrostatic signal. The bubble size was estimated based on the electrostatic signal. The experimental results showed that the addition of pulsed airflow had a certain effect on the bubble size. As the pulse frequency increases, the bubble size would first decrease and then increase, and it reached the minimum when the pulse frequency was about 0.5Hz. Moreover, the addition of the pulsed airflow reduces the bubble size and improved the particle fluidization effect, so the agglomerated particles quality was significantly reduced after the completion of fluidization in the olefin fluidized bed.

Key words: two-phase flow, fluidized-bed, pulsed airflow, bubble, flow, agglomeration

中图分类号:

TK224

王蕾, 陈东辉, 杜长河, 李洪伟, 洪文鹏. 脉冲气流对烯烃流化床气泡特性的影响[J]. 化工进展, 2021, 40(12): 6540-6546.

WANG Lei, CHEN Donghui, DU Changhe, LI Hongwei, HONG Wenpeng. Effect of pulsed airflow on bubble characteristics of olefin fluidized bed[J]. Chemical Industry and Engineering Progress, 2021, 40(12): 6540-6546.

图/表 13

参考文献 16

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理论速度/m·s^-1	测量次数	测量速度/m·s^-1	速度偏差/m·s^-1
0.94	1	0.84	0.10
	2	0.81	0.13
	3	0.79	0.15
	4	0.76	0.18
0.62	1	0.67	0.05
	2	0.58	0.04
	3	0.54	0.08
	4	0.48	0.14

理论速度/m·s^-1	测量次数	测量速度/m·s^-1	速度偏差/m·s^-1
0.94	1	0.84	0.10
	2	0.81	0.13
	3	0.79	0.15
	4	0.76	0.18
0.62	1	0.67	0.05
	2	0.58	0.04
	3	0.54	0.08
	4	0.48	0.14

测量次数	法拉第筒法/μC·kg^-1	静电法/μC·kg^-1	荷质比偏差/%
1	3.42	3.65	6.73
2	3.38	3.46	8.00
3	3.14	3.31	5.41
4	3.02	3.22	6.62
5	2.85	3.03	6.43
6	2.73	2.89	5.86
7	2.56	2.77	8.20
8	2.47	2.64	6.88

测量次数	法拉第筒法/μC·kg^-1	静电法/μC·kg^-1	荷质比偏差/%
1	3.42	3.65	6.73
2	3.38	3.46	8.00
3	3.14	3.31	5.41
4	3.02	3.22	6.62
5	2.85	3.03	6.43
6	2.73	2.89	5.86
7	2.56	2.77	8.20
8	2.47	2.64	6.88

脉冲频率/Hz	总风速/m·s^-1	平稳风速/ m·s^-1	脉冲风速/ m·s^-1
0	0.81	0.72	0.09
0.05
0.0625
0.1
0.2
0.5
1
2.5