Structural design and performance analysis of gas-liquid ejector

doi:10.16085/j.issn.1000-6613.2019-1235

Abstract

Abstract:

Jet loop reactors (JLR) are widely used in industry, such as biochemical, chemical, refrigerant processes and environmental protection, due to their favorable heat and mass transfer and mixing characteristics. As one of the core components of the jet loop reactor, the structure size of the gas-liquid ejector has significant influence on mass transfer characteristics and application environment of the jet loop reactor. For the purpose of exploring the effect of structure size on the ejector performance, a bench-scale gas-liquid ejector was designed according to its working principle, and its performance was tested by a cold model experiment. The results showed that the gas entrainment capacity of the ejector depends on the cross-section ratio of its mixing throat and nozzle outlet (f₃/f₁), as well as the pressure drop at the inlet and outlet pressure of the ejector (Δp_p/Δp_c), while the gas holdup of the loop reactor is only related to the liquid flow rate and the gas entrainment rate. Under the same liquid flow conditions, the maximum gas entrainment rate of the ejector increases with the rise of the section ratio f₃/f₁, and the average gas holdup in the reactor increases accordingly. The shear effect between the two fluids can be enhanced through increasing the velocity difference between the liquid jet and the ejector gas, which can also make the bubbles more susceptible to breakage. The study also found that the mixed fluid in the reactor can reach the emulsifying state in the case of the gas-liquid ratio of the ejector is greater than 2.6.

Key words: ejector, gas-liquid flow, gas entrainment rate, gas holdup, bubble

摘要：

喷射式环流反应器是一种高效的多相反应器，由于其具有良好的传热、传质和混合特性，目前已被广泛应用于生物、化学、制冷和环境保护等工程领域。气液喷射器作为喷射式环流反应器的核心部件之一，其结构尺寸对环流反应器的传质特性和适用环境都具有显著影响。为考察结构尺寸对喷射器性能的影响，本文根据其工作原理，设计了一台模试气液喷射器，并通过冷模试验对其进行性能测试研究。试验结果表明：气液喷射器的引气能力主要取决于其混合喉管与喷嘴出口截面比f₃/f₁以及喷射器进出口压力降Δp_p/Δp_c，而环流反应器的气含率仅与喷射器的液相射流量和气体引射量有关。相同液相流量条件下，喷射器的最大引射空气量随截面比f₃/f₁的增大而增大，反应器内的平均气含率随之增加；提高液相射流与引射气体的速度差能够加强两股流体间的剪切作用，使气泡更易发生破碎。当喷射器的气液比大于2.6时，反应器内的混合流体可达到乳化状态。

关键词: 喷射器, 气液两相流, 气体引射量, 气含率, 气泡

CLC Number:

TQ052.5

Lei HE,Yi SU,Tao JIE,Jian LIANG,Zhaofan TANG,Bingbing YANG,Shicheng ZHANG. Structural design and performance analysis of gas-liquid ejector[J]. Chemical Industry and Engineering Progress, 2020, 39(4): 1245-1251.

何磊,苏毅,揭涛,梁健,唐昭帆,杨冰冰,张世程. 气液喷射器的结构设计与性能分析[J]. 化工进展, 2020, 39(4): 1245-1251.

Figures/Tables 2

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