Effect of nozzle structure on mixing and mass transfer characteristics in jet bubbling reactor

doi:10.11949/j.issn.0438-1157.20180535

Abstract

Abstract:

The nozzle structure has an important influence on the mixing and mass transfer performance of the jet bubbling reactor. In this paper, air-water is used as the simulation medium, and the double-probe conductivity probe, electrolyte tracer method and dynamic dissolved oxygen method are used to compare the bubble size distribution in the jet bubbling reactor with the reduced diameter circular nozzle and the rotary triangular nozzle. The results show that the variation rules of the average gas holdup, the liquid mixing time and the liquid volumetric mass transfer coefficient with the increase of the superficial gas velocity and the liquid jet Reynolds number in the jet bubbling reactors with two kinds of nozzles are the same. Compared with the case with necking circular nozzle, the bubble size is smaller, the average gas holdup is higher and the mixing time is shorter in the case with twisted triangular nozzle. The nozzle structure has little influence on the gas-liquid mass transfer coefficient when the gas input power accounts for more than 20% of the total input power. However, the gas-liquid mass transfer performance of the twisted triangular nozzle is better than that of the necking circular nozzle when the gas input power accounts for less than 20% of the total input power. The research results can provide theoretical guidance for the optimization of the nozzle structure in the industrial jet bubbling reactor.

Key words: mixing, mass transfer, bubble, gas-liquid flow, nozzle structure

摘要：

喷嘴结构对射流鼓泡反应器的混合和传质性能具有重要的影响。以空气-水作为模拟介质，使用双探头电导探针、电解质示踪法和动态溶氧法，对比研究了缩径式圆形喷嘴和旋扭三角形喷嘴对射流鼓泡反应器中气泡尺寸分布、平均气含率、液相混合时间和气液传质系数的影响规律。实验发现，随着气速或液体射流Reynolds数的增大，两种喷嘴对应的平均气含率、液相混合时间和气液传质系数具有相同的变化规律；与缩径式圆形喷嘴相比，采用旋扭三角形喷嘴的射流鼓泡反应器中气泡尺寸更小，平均气含率更高，宏观混合时间更短；当气体输入功占总输入功比例超过20%时，喷嘴结构对气液传质系数的影响较小，当气体输入功占总输入功比例小于20%时，旋扭三角形喷嘴的气液传质性能优于缩径式圆形喷嘴。研究结果可为工业射流鼓泡反应器喷嘴结构的优化提供理论指导。

关键词: 混合, 传质, 气泡, 气液两相流, 喷嘴结构

CLC Number:

TQ027.1

HUANG Zhengliang, SHUAI Yun, YANG Yao, SUN Jingyuan, WANG Jingdai, YANG Yongrong. Effect of nozzle structure on mixing and mass transfer characteristics in jet bubbling reactor[J]. CIESC Journal, 2018, 69(11): 4648-4654.

黄正梁, 帅云, 杨遥, 孙婧元, 王靖岱, 阳永荣. 喷嘴结构对射流鼓泡反应器混合和传质性能的影响[J]. 化工学报, 2018, 69(11): 4648-4654.

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