MASS TRANSFER AT LOW FLOW RATES IN A PACKED COLUMN

Journal Article · Mon Jun 01 04:00:00 EDT 1959 · A.I.Ch.E. Journal

DOI:https://doi.org/10.1002/aic.690050203· OSTI ID:4226379

Dorweiler, V P; Fahien, R W

Mass transfer in packed columns has been investigated for a variety of column and packing sizes but at flow rates restricted to fully developed turbulent conditions. The present work was undertaken to investigate mass transfer at flow-rate conditions in the transition and laminar regions. A dual treatment of experimental data required a knowledge of the variation of concentration and velocity with radial position. A tracer-injection technique was employed which consisted in the introduction of a tracer gas into the center of a bulk gas stream and the measurement of the tracer-gas concentration at various radial positions downstreanm. The velocity distribution for the packed column was determined by means of a five-loop, circular, hot-wire anemometer. The test column was a vertical 4-in. pipe, packed with 1/4-in. spherical, ceramic catalyst-support pellets. Mass transfer diffusivity and Peclet nunmber were determined from two solutions of the differential-diffusion equation applied in previous investigations. An analytical solution in terms of Bessel functions was used to calculate values of average diffusivity and Peclet number and a seminumerical solution in terms of homogeneous lineardifference equations to calculate values of point diffusivity and Peclet number. Variation of diffusivity and Peclet number with radial position is shown, average diffusivity and Peclet number being correlated with Reynolds number. The interaction of molecular and eddy mass transfer mechanisms with decreasing mass velocity is illustrated by defining a molecular and an eddy Peclet number and correlating with Reynolds number. Eddy diffusivity is correlated as a function of local flow conditions. (auth)

• Research Organization: Iowa State Coll., Ames
• NSA Number: NSA-13-017216
• OSTI ID: 4226379
• Journal Information: A.I.Ch.E. Journal, Journal Name: A.I.Ch.E. Journal Vol. Vol: 5
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CATALYSIS
CERAMICS
CONFIGURATION
DIFFERENTIAL EQUATIONS
DIFFUSION
EQUATIONS
EXTRACTION COLUMNS
FLUID FLOW
FLUIDIZATION
GASES
GRAIN SIZE
HEAT TRANSFER
HEATING
INJECTION
MATHEMATICS
MEASURED VALUES
MOLECULES
PARTICLES
PECLET NUMBER
PELLETS
PHYSICS AND MATHEMATICS
PIPES
REYNOLDS NUMBER
TRACER TECHNIQUES
TRANSIENTS
TURBULENCE
VARIATIONS
VELOCITY
WIRES