Study On Gas-liquid Mass Transfer In Multiphase Flow System

Gas-liquid contact operation is widely applied in the processes of metallurgy,petrochemicals,chemical engineering,etc.The gas-liquid dispersion and mass transfer between gas and liquid are playing important roles in the design and optimization of gas-liquid contact equipment.In addition,gas-liquid mass transfer has a close relationship with the fluid flow.In the past,the experimental and theoretical study on the gas-liquid mass transfer characteristics in multiphase flow systems mainly focused on the relatively stagnant system.Most of the researchers calculated the mass transfer coefficient of the rising bubbles in stationary water or relatively stationary bubbles in the flowing liquid.However,the turbulent systems are often used in many industrial processes such as petrochemicals,biochemicals,etc.Therefore,the study on the mass transfer performance of multiphase systems in turbulent systems is significant for practical industrial applications.In this paper,the high-speed camera imaging technology was used to experimentally measure the mass transfer of single oxygen bubbles in sodium sulfite solution under different turbulent flow conditions and at different flow rates.The images of oxygen bubbles changing with time were analyzed and processed using MATLAB program to obtain the volume reduction of bubbles in high accuracy and to calculate the mass transfer coefficient.The results show that the mass transfer coefficient will increase with the increase of sodium sulfite solution concentration,oxygen bubble size and the solution flow rate.This work also analyzes and establishes the relationship between the mass transfer coefficient and different factors.After the dimensionless analysis,the semi-empirical formulas between the Sh number and Sc,Re are obtained.The results show that the correlation is in good agreement with the experimental values with the relative error less than 10%.The effect of chemical reaction on the mass transfer coefficient was also studied in this paper.Results show that the mass transfer between gas and liquid was enhanced by the chemical reaction.Compared with the cases without chemical reaction under the same conditions,the mass transfer coefficient is increased by 1?4 times.With the increase of the solution concentration,the enhancement effect becomes more obvious.This study can provide guidance for the design and optimization of the gas liquid reactors such as ?-olefin and PAO reactors.