Comparison And Performance Study On Microbubble Generators

The reaction temperature of gas-liquid reactors is easy to control and the selectivity of reaction in gas-liquid reactors is high.So it is widely used in petroleum refining,sewage treatment and so on.The bubble size in the gas-liquid reactors has a significant effect on the mass transfer and heat transfer performance of the reaction.Compared with macrobubbles under conventional conditions,microbubbles have unique advantages such as high internal pressure,large specific surface area and long residence time in liquid phase.Therefore,microbubbles are often used to enhance the mass transfer effect of multiphase flow in industrial production.Now,the conventional microbubble generators are easy to wear and block,and its gas-liquid ratio is relatively low.It is necessary to optimize the structural parameters and operating conditions of microbubble generators.The program of microbubble image extraction and particle size identification was designed and compiled in order to accurately characterize the size distribution of the microbubble in the microbubble generators.This program can be used to extract and summarize the data of microbubble images.The particle size distribution and average diameter of bubbles in the images were obtained through the process of image preprocessing,circularity value clustering,second-order improved watershed algorithm,and feature parameter sieving of segmented block area.The results of this method are not significantly different from manual processing,and the processing speed is greatly improved compared with manual processing.A set of microbubble preparation and measurement device was designed and built.The effects of structural parameters such as the angle of expansion section on local pressure,microbubble particle size distribution and average diameter were studied using two-dimensional venturi microbubble generators.The best expansion angle is optimized to be 12.5°.The effects of operating parameters such as throat liquid velocity and air intake on local pressure,microbubble particle size distribution and average diameter were studied.The optimum throat liquid velocity is 11 m/s.A three-dimensional venturi microbubble generator was designed and processed according to the above data.And its suitable throat liquid velocity,air intake and other operating conditions were further optimized.The preferred throat liquid velocity is 10 m/s,and the preferred air intake is3.8 L/min.The microbubble preparation performance of the two-dimensional microbubble generators and the three-dimensional microbubble generator was compared.The average diameter of the microbubbles produced by the three-dimensional venturi microbubble generator is more than 60 μm smaller than that of the two-dimensional venturi microbubble generator,and the particle size distribution of three-dimensional venturi microbubble generator is narrower.