Measurements of the terminal velocity of liquid drops immersed in an insoluble liquid were made for eleven liquid systems, covering a wide range of physical properties: continuous-phase density 0.960 to 1.145 g./cc., viscosity 0.93 to 1.56 centipoises; dispersed-phase density 0.807 to 1.674 g./cc., viscosity 0.59 to 72.1 centipoises; interfacial tension 0.3 to 42.4 dynes/cm. A correlation of the data was developed for each of the two velocity-dropdiameter regions which permits easy computation of the drop velocities. The correlations are shown to reproduce the present data and much of the published data very satisfactorily.Photographs permitted measurement of the drop eccentricities, which are shown to be a function of the drop diameter, density difference, and interfacial tension.Several recent papers (S, 5, 6) EXPERIMENTAL DETAILSThe drops were allowed to rise or fall in a glass-walled tank of square cross section 10 by 10 in., 40 in. tall, made from %-in. plate glass and brass angles, with brass end plates, the whole kept leaktight with Permanite cement. The tank was filled with the liquid through which the drops were to move (continuous liquid). Liquid to form the drops (dispersed liquid) flowed by gravity from a separatory-funnel reservoir through two pipettes in series, of 1-and 5-ml. capacity, through a needle valve to control the rate of flow, and thence to a brass or stainless steel sharp-edged nozzle, from which it issued into the continuous liquid. The nozzles entered the tank through the upper or lower end plates, depending upon whether drops were to fall or rise. Nine nozzles were used, varying in internal diameter from 0.018 to 0.516 in., in order to obtain the desired range of drop sizes. The temperature of the system was measured by a thermometer suspended in a corner of the tank.

No abstract

1 V 1 = absolute value (magnitude) of oscillation in vapor X B = bottoms composition, mole fraction water X D = distillate composition, mole fraction water X F = feed composition, mole fraction water T~ = linear time constant, min.boilup McGraw-Hill, New York (1963). TN = nonlinear time constant, min. p = slope of Tc versus V line between limits on Tc w = frequency, rad./min.

Solution rates of 1h-, %-, and 1-in. cast benzoic acid spheres were measured under naturaland foreed-convection conditions. Upward-flowing streams of water and aqueous propylene glycol, in laminar and turbulent flow, were used to contact single spheres in either a 1.50-or 4.00-in.-diameter column. Sphere Reynolds numbers ranged from 10 to 16,920; Schmidt numbers from 987 to 69,680; sphere-to column-diameter ratios, ds/dc, from 0.123 to 0.497; and Grashof numbers from 5,130 to 125,200.The Sherwood number was found independent of the laminar-turbulent transition for pipe flow and the sphere-to column-diameter ratio when the Reynolds number is based on the average fluid velocity and sphere diameter.

No abstract

The mass transfer coefficient in covered, right-cylindrical tanks full of liquid, turbulently agitated at various speeds by turbines with six flat blades, was measured by the rate of solution of suspended solids in water and in 45% sucrose solutions.Screened crystals in the following U. S. mesh sizes were used: boric acid: 18/20, 16/18, 16/20, 14/16, 12/14, 10/12, 8/10, 6/8; rock salt: 6/8, 4/6. Pellets were benzoic acid: 0.126 in. long by 0.218-in. diam.; salt: 0.565-in. diam. by 0.531-in. long (over rounded ends).Tanks were 6, 12, 18, and 30 in. Turbines were 2, 3, 4, 6, 9, and 12 in. in diameter, centrally located. Four full-length baffles 10% of the tank diameter wide were spaced at 90 deg. A few runs were made without baffles.The coefficient of mass transfer was found to be independent of particle size and Schmidt number (Ns, = 735 to 62,000) and could be correlated with turbine Reynolds number in each tank, with larger tanks yielding smaller coefficients at the same N R~. An empirical equation which fits all the data from the baffled tanks within about 4% (in the range 0.1 < k < 2) isIn ( A treatment of the data according to dimensionless groups provides another correlation:t is shown that for the systems used 1 / D is essentially proportional to Ns,".", and so the effect of diffusivity here is only apparent.A recent review of the available information for computing the stage efficiency of mixer-settler extractors (1 9 ) revealed the severe limitations of our knowledge of the mass transfer coefficients for the continuous phase which surrounds the dispersed particles in the mixer. For baffled vessels e TURBINE SHAFl SAMPLER (SEEFIG 3) \

A method of designing adiabatic packed-tower gas absorbers and strippers, in which the mass-and heat-transfer resistances of the liquid phase are accounted for, has not been worked out.Sherwood and Pigford (75) have outlined a procedure when the liquidphase resistances are ignored. While, in most cases, they are small relative to those in the gas, ignoring them can lead to important errors.

No abstract