LONGITUDINAL DISPERSION IN PACKED EXTRACTION COLUMNS WITH AND WITHOUT PULSATION

Technical Report · Wed Oct 23 00:00:00 EDT 1963

OSTI ID:4144114

Moon, J S; Hennico, A; Vermeulen, T

Single-phase Peclet numbers were measured by an unsteady-state step- input method. For pulsed columns, the use of pulsation serves to decrease the Peclet numbers as the amplitude increases, and to a lesser extent as the frequency increases. The effect is somewhat more pronounced in beds of Raschig rings and Berl saddles than in beds of uniform spheres. The Peclet-number decrease diminishes with increasing fluid viscosity and also with increasing flow rate; the results indicate a rise in Peclet number for viscous fluids. For unpulsed columns, Peclet numbers in the low-Reynolds-number regime down to a Reynolds number of 0.04 were obtained, using 0.0058-in.-diameter glass beads as a packing material. The modified Peclet number P remained constant at 0.205 plus or minus 0.020. Peclet numbers for counterflowing liquid-liquid systems were measured for both continuous and dispersed phases, with the behavior of the latter depending upon whether it does or does not wet the packing material. For both pulsed and unpulsed columns, the axial Peclet number of one phase decreases as the flowrate of the other phase increases. The effect is much greater for the continuous than for the dispersed phase, and also for the dispersed-phase wetting rather than nonwetting. A correlation was developed for dispersedphase Peclet number without pulsation, which includes the physical propehies for the dispersed phase. The measurement of both dispersed- and continuous-phase concentration profiles was undertaken to determine the applicability of the Miyauchi model to steady-state mass transfer, using the Peclet numbers obtained from unsteady-state conditions. Experimental profiles inside the packed bed were compared with the theoretical profiles, and the agreement between these two profiles was quite satisfactoty. It is concluded that the one-dimensional diffusion model adequately represents the fluid behavior in packed-bed extraction columns with and without pulsation. With appropriate Peclet numbers for both phases, this model should be very useful for accurate and economical design of packed columns. The Peclet numbers determined by the unsteadystate tracer-injection method appear to represent closely the longitudinal-dispersion behavior during steady-state extraction. (auth)

• Research Organization: California. Univ., Berkeley. Lawrence Radiation Lab. and California. Univ., Berkeley
• DOE Contract Number: W-7405-ENG-48
• NSA Number: NSA-18-006886
• OSTI ID: 4144114
• Report Number(s): UCRL-10928
• Resource Relation: Other Information: Orig. Receipt Date: 31-DEC-64
• Country of Publication: United States
• Language: English

Related Subjects

CHEMISTRY
CONFIGURATION
COUNTER CURRENT
DIAGRAMS
DIFFUSION
DISTRIBUTION
ECONOMICS
EXTRACTION COLUMNS
FLUID FLOW
FREQUENCY
GLASS
GRAIN SIZE
HEAT TRANSFER
LIQUID FLOW
LIQUIDS
MATHEMATICS
MEASURED VALUES
MIXING
MOCKUP
PECLET NUMBER
PLANNING
QUANTITY RATIO
REYNOLDS NUMBER
SEPARATION PROCESSES
SOLUBILITY
SOLVENT EXTRACTION
SPHERES
TABLES
TRACER TECHNIQUES
TRANSPORT THEORY
TURBULENCE
USES
VARIATIONS
VISCOSITY