Investigations Of The Behaviors Of Dispersed Phase On Liquid-liquid Two-phase Flow In Pulsed Sieve Plate Column

The droplet’s diameter and distribution is one of the most important issues in pulsedextraction. Meanwhile, it has been acknowledged that the behavior of the dispersed phasedroplet in the extraction column is closely related to the design of pulsed sieve plateextraction column, the two-phase heat transfer and mass transfer in the column and pulsedextraction. Therefore, it is of great significance to pulsed extraction to figure out thedistribution law of liquid-liquid two-phase flow dispersed phase droplet and work out acorrelation to predict the size of droplet.This project mainly focuses on the size and distribution of the liquid-liquid two-phaseflow dispersed phase droplet in pulsed sieve plate extraction column. The size of droplet ismeasured through the method of non-contact measurement with a camera photographing,i.e., compiling the camera drive under the Linux circumstance to control the camera to takea picture of the two-phase flow dispersed phase running droplet in the extraction columnand then obtaining the diameter of the droplet with the help of a droplet size measuringsoftware compiled by the author. After the analysis of the obtained diameter, it is found thatthe change law of the droplet Sauter mean diameter in the state of emulsion regime isdifferent from the behavior of the droplet in the mixer-settler regime and dispersed regimein literature. When the two-phase flow is in the emulsion regime, the droplet diameterchanges with systems changing. In the system of water/n-dodecane, the Sauter meandiameter fluctuates after pulsation velocity changes. In the system of water/tributylphosphate(30%)+dodecane(70%), the Sauter mean diameter of the droplet falls afterincreasing with the increase of pulsation velocity, while in the system of0.5mol/L HNO3/tributyl phosphate(30%)+dodecane (70%), it changes slowly and then dramatically andfinally falls. It is relatively obvious that the droplets mean diameter varies with the flowratio, i.e., in different systems, it decreases with increase of the continuous phase flow/dispersed phase flow.A large amount data of diameters obtained with the image processing software hasbeen analyzed statistically. Through the histogram of droplet diameter distribution, typedistribution test and probability function fitting, it is observed that the droplet distributionagrees with lognormal distribution. Using the correlation of the droplet size in pulsed sieveplate extraction column proposed by Hartland to predict droplet size, the concerned parameters are acquired,and the deviation of the predicted droplet diameter is large. It hasbeen found that by modifying the hartland correlation and adding the ratio term of flowingrate it can predict the droplet diameter in sections more accurately.