Study On The Hydrodynamic Characteristics In ф50 Pulsed Extraction Column With Discs And Doughnuts

The method of air-purge to measure holdups and the hydrodynamiccharacteristics of the 50mm-diameter discs and doughnuts pulsed extraction columnwith 1mol/L HNO3 solution and 30%TRPO-Kerosene solution are studied in thispaper. The time-averaged frictional pressure drop and the influences of theparameters of column configuration and operation on the hydrodynamiccharacteristics have investigated.The experimental results using the method of air-purge to on-line determine theholdup of dispersed phase in the discs and doughnuts pulsed extraction columnindicate as follows:(1) if the single-phase flow rate is equal to zero or the flow ratio of thetwo-phase is one, the time-averaged frictional pressure drop is zero.(2) When the single-phase flow rate is not zero, the influence of pulsedintensity on the time-averaged frictional pressure drop is distinct. For HNO3solution, the influence factor, C0, defined from the Noh's model, decreases withthe increasing of the plate spacing and packing free-area. However for the30%TRPO-Kerosene solution, C0 has no relation to the plate spacing, increaseswith the increase of Reynolds number and but reduces with the increase ofpacking free-area.(3) When the flow ratio of the two-phase is not one, the time-averagedfrictional pressure drop can be predicted by the equation for single-phase flowwhere the flow rate refers to that of the corresponding continuous phase. Theholdup calculated from Noh's model is in good agreement with that measured bythe method of volume substitution.The study on the hydrodynamic characteristics of the discs and doughnuts pulsedextraction column includes flooding characteristics and the holdups of dispersedphases. The experimental results indicate as follows:(1) the flooding flux increases with the decreasing of pulsed intensity, theincreasing of flow ratio and the increasing of packing free-area, while theflooding-holdup of the packing free-area of 23% is larger than that of 17% and30%.(2) Within the normal operation, the holdup increases linearly with the flowrate of continuous phase and the flow ratio of two-phases, while the effect of thepulsed intensity, packing free-area and the plate spacing on the holdup iscomplicated because of the interaction of the three parameters. Comparison to thecolumn of 17% and 30%, the influence of the pulsed intensity and plate spacingon the holdup of that of 23% is dominated.Therefore, when the column is applied in 30%TRPO-Kerosene and HNO3system, the best packing free-area of the discs and doughnuts pulsed extractioncolumn is suggested to be 23%.