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浙江大学学报(工学版)
J4  2010, Vol. 44 Issue (2): 305-309    DOI: 10.3785/j.issn.1008-973X.2010.02.017
    
Flow pattern and its transition of different particles in gas-solid fluidized bed
REN Cong-jing, WANG Jing-dai, YANG Yong-rong
(State Key Laboratory of Chemical Engineering, Zhejiang University, Hangzhou 310027, China)
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Abstract  

The flow pattern of gas-solid fluidized bed was detected through experiments with different Geldart group particles based on acoustic emission (AE) method. The relationship between the energy of acoustic signal with the bed height was analyzed. Results showed that the flow pattern of high density polyethylene (group B particles) was multi-circulation pattern, in which there were main-circulation zone, sub-circulation zone and stagnant zone. According to the relationship between AE signal energy and bed height, the position of stagnant zone can be detected which was just in the boundary of main-circulation zone and sub-circulation zone. For rapeseed (group D particles), the flow pattern was single-circulation pattern with smaller region of uniform fluidization. Bimodal polyethylene (group A/C particles) also performed single-circulation flow pattern and had more main-circulation zone than group D particles. For bimodal polyethylene, experiments were conducted in a 150 fluidized bed with agglomerations of different size to monitor the flow pattern under normal condition and fault condition. Results show that the single circulation flow patter in fluidized bed can change to the multi-circulation flow pattern for the same particles when the size of agglomeration reached to 8 cm. The method can monitor the fluidization and the position of agglomeration.

Published: 09 March 2010
CLC:  TQ 021.1  
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Cite this article:

LIN Cong-Jing, WANG Jing-Dai, YANG Yong-Rong. Flow pattern and its transition of different particles in gas-solid fluidized bed. J4, 2010, 44(2): 305-309.

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http://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2010.02.017     OR     http://www.zjujournals.com/eng/Y2010/V44/I2/305


气固流化床中不同颗粒的流动模式及其转变

利用声发射（AE）测量技术,针对不同的Geldart分类颗粒体系,结合声能量分析,得到不同颗粒流化时的流动模式.对于高密度聚乙烯（B类颗粒）,声信号能量沿床高呈现不同的变化规律,流化床呈现双循环的流动模式,床内存在大小两个循环,大小两个循环的分界线即为颗粒流化滞留区域；对于油菜籽（D类颗粒）,流化时为单循环流动模式,流化均匀的区域较小；对于双峰聚乙烯（A/C类颗粒）,颗粒流化时呈现单循环流动模式,流化均匀区域较D类颗粒大.对双峰聚乙烯颗粒,在内径为150 mm的流化床中加入不同量的结块,考察正常流化以及故障情况下的流动模式.实验发现,当体系内的结块直径到达8 cm时,流型将发生突变,由单循环流动模式转变为双循环流动模式,利用声信号能量的变化规律可以判定双峰聚乙烯颗粒的流化状况以及产生结块的位置.

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