Flow-mass Transfer Mechanism Of Two-phase Flow In Gas-liquid Countercurrent Impinging Scrubber

The gas-liquid countercurrent impinging scrubber can be used to complete the gas-liquid mass transfer effectively due to the fact that the gas-liquid two-phase kinetic energy is utilized and then a foam zone within the scrubber is formed.The liquid nozzle is one of the most key parts in the scrubber.In this paper,a new reverse jet nozzle proposed by China University of Petroleum(Beijing)which can independently regulate the axial and tangential volume flow rates is investigated.In the previous study,the flow-mass transfer characteristics of gas-liquid two phases in the scrubber were investigated only for the dissolved oxygen water-air system.In this paper,two aspects were mainly investigated by cold mold experiments with the methods of the dissolved oxygen,the double-sensor conductivity probe and the pressure sensor.Firstly,the gas-liquid two-phase mass transfer performance of nozzles with different structures was studied.Combining the measured desorption rates with the observed flow patterns,the optimal structural dimensions were determined.Secondly,by varying the viscosity of the washing liquid,the characteristics of the flow-mass transfer in the scrubber were studied.In other words,the relationship among the parameters of the gas phase holdup,the pressure and the mass transfer under different viscosities was determined.The experimental results show that,the effect of viscosity on mass transfer is not merely monotonically increasing/decreasing.However,the desorption rates under the condition of median viscosity of the washing liquid present the maximal value.At the same time,in addition to the foam pattern(Q_A/Q_T=0.4?0.6)in the scrubber,the annular pattern(Q_A/Q_T=1.2?1.5)also shows quite desirable mass transfer performance.Within the viscosity range of this article,the variation tendency of the pressure under different axial-tangential volume flow ratios is similar to the change of the desorption rates under the same liquid flow rate.That is,a good mass transfer pattern also closely relates to a high pressure value.The local gas phase holdup and the local pressure present clear relationship.It means that these two parameters are highly coupled——it is also the basis for judging the local pressure contribution.Based on the experimental results,the empirical correlations both for the desorption rate and the pressure drop are given,and the calculated and the measured results agree well respectively,which can be used for engineering design purpose.