Optimizing conical nozzle of venturi ejector in ejector loop reactor using computational fluid dynamics
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pISSN: 0256-1115 eISSN: 1975-7220
INVITED REVIEW PAPER
INVITED REVIEW PAPER
Optimizing conical nozzle of venturi ejector in ejector loop reactor using computational fluid dynamics Enle Xu*,**, Xiaofeng Jiang*,**,†, and Long Ding*** *School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, P. R. China **Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China ***Weihai New Era Chemical Machinery Co., LTD, Weihai 264200, P. R. China (Received 23 January 2020 • Revised 19 May 2020 • Accepted 8 June 2020) AbstractThe structure of a conical nozzle is critical to the gas induction of a venturi ejector. In this work, the effect of nozzle structure on the gas induction was investigated by means of multiphase CFD and validating experiments. Under different structures, the maximal gas induction was obtained through analyzing the nozzle outlet velocity (NOV), nozzle inlet velocity (NIV), as well as nozzle shrinking angle (NSA). The simulated inlet pressure is positively proportional to inlet flow rate, which is in good agreement with experimental results. The simulated results reveal that the inlet pressure and gas induction increase with the increasing NOV. Considering the operational characteristics of centrifugal pump, the recommended NOV is about 21.8 m/s. NIV and NSA show little impact on gas induction and inlet pressure. Based on the pipeline energy consumption, the recommended NIV is the same as the outlet velocity of centrifugal pump. The recommended NSA is about 20o to obtain the maximal gas induction. Keywords: Conical Nozzle, Gas Induction, Nozzle Outlet Velocity, Nozzle Shrinking Angle, Nozzle Inlet Velocity
tor. The key components of the venturi ejector are the conical nozzle, suction chamber, mixing tube and diffuser. The liquid from the recycling pump is accelerated in the conical nozzle. According to Bernoulli’s theorem, the static pressure drop generates a vacuuming effect at the nozzle outlet. The gas is drawn into the suction chamber by the pressure difference. The dispersion between liquid
INTRODUCTION Effective dispersion between gas phase and liquid phase is important in the chemical industry, such as multiphase reactions [13]. An ejector loop reactor (ELR) is more and more appreciated as a typical multiphase mixed reactor [4-7]. Fig. 1 provides a schematic diagram of the ELR, which mainly consists of recycling pump, venturi ejector, heater exchanger and vessel. The gas phase is introduced into the venturi ejector by the high speed liquid from the recycling pump. The mixing behavior of gas and liquid phases occurs in the venturi ejector and vessel. The recycling pump provides all the power for this system. Compared to the stirred tank reactor [8-11], ELR exhibits high efficiency of heat and mass transfer due to the heat exchanger and recycling pump. Furthermore, ELR is preferred for a high pressure reaction and the easy scale-up ability with th
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