Courtesy. The Fluor Corporation
(Pages 423-501)
Atmospheric Cooling Tower of the Wiltshire Oil Company, Lor Angeles, Calif.
The
Role of Diffusion in Engineering Operations T. I PI
n
m' 100 2 \
3 .
5 I
80 '
0:
a
60
0 W
2 m
40
U u)
LL
0
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n
20
-I
a
I
+ 2 W
0 40
60
80
WATER TEMPERATURE
FIGURE 5.
100
I20
,O F .
METHODOF DESIGKING COOLING TOWERS
The papers included in the present symposium contain new information and ideas relating to several of the important diffusional processes. Two papers treat of the basic molecular diffusion (page 443) and the relation of diffusivity to thermal conductivity and viscosity (page 430). One (page 436) relates heat and mass transfer in n wetted-vall tower, this type of apparatus having proved to be of great value for
April, 1941
INDUSTRIAL AND ENGINEERING CHEMISTRY
429
Courtesu, Foster- Wheeler Corporation
FORCED-DRAFT COOLING TOWER IN basic studies. Two other papers (pages 467 and 459) describe new methods of calculation useful in design caloulations, facilitating application of diffusion theory to practical engineering problems. Two papers offer new data and correlations for the case of mass transfer between a liquid and a suspended solid (pages 453 and 478), and two others present semiplant-scale performance data on gas absorption in packed towers (page 485) and bubble-cap columns (page 493). The paper on gas separation (page 474) discusses the practical possibilities of separating gases by a novel diffusional method. The papers cover diffusion and heat transfer in gases, liquids, and solids; interphase mass transfer between gases and liquids, liquids and liquids, solids and liquids, and solids and gases; and heat transfer between gases and liquids.
Acknowledgment The stoneware tower and Berl saddles used in the tests on ammonia absorption were kindly donated by the Maurice A. Knight Company. The ammonia and acid used were given by the du Pont Company and the Monsanto Chemical Company, respectively. The data presented in Figure 2 were obtained b y L. L. Fellinger, whose complete results will be published at a later date.
Nomenclature interfacial surface, sq. ft./cu. ft. enthalpy of air plus water vapor, B. t. u./lb. dry air = solute concentration corresponding to equilibrium with solute partial pressure in main body of gas, lb. moles/ cu. f t . Ci = solute concentration in liquid a t interface, lb. moles/ cu. f t . CL = solute concentration in main body of liquid, Ib. moles/ cu. ft. G = gas (or dry air) rate, lb./(hr.)(sq. ft.) hl = tower height, ft. H = absolute humidity, lb. water/lb. dry air H. T. U. = height of a transfer unit, f t . K = over-all coefficient, lb./(hr.)(s . ft.)(unit A H ) k~ = gas film coefficient, Ib. moles/&r. (sq. ft.) atm.) ~ G U = gas film coefficient, Ib. moles/(hr.](cu. ft.){atm.) KG = over-all coefficient, lb. moles/(hr. (sq. ft.)(atm.) KQU = over-all coefficient, Ib. moles/(hr.](cu. ft.)(atm.) = liquid film coefficient, lb. moles/(hr.)(sq. ft.)(lb. mole/ cu. ft.) k ~ a = liquid film coefficient, lb. moles/(hr.)(cu. ft)(lb. mole/ cu. ft.) a B CG
= =
A
SEVEN-CELL REFINERY over-all coefficient, lb. moles/(hr.)(sq. ft.)(lb. mole/cu. ft.) = over-all coefficient, lb. moles/(hr.) (cu. ft.) (lb. mole/cu. ft.) = liquor rate, lb./(hr.)(sq. ft. of tower cross section) = Henry law coefficient, lb. moles/(cu. ft.)(atm.) = number of traqsfer units = rate of mass transfer, lb. moles/(hr.)(sq. ft. interface) = partial pressure of solute gas in main body of gas mixture, atm. = partial pressure of solute gas a t interface, atm. = partial pressure of solute as corresponding to equilibrium with main body of %quid, atm. = latent heat of vaporization, B. t. u./lb. = humid heat, B. t.ou./(lb. dry air)(’ F.) = air temperature, F. = water temperature, F. = over-all coefficient of heat transfer, B. t. u./(hr.)(sq. ft.)(” F.) = liquor density, lb./cu. ft. =
O
Literature Cited Am. SOC.Refrig. Engrs., Refrigerating Data Book,
p. 191 (193940). Ceaglske, N. H., and Hougen, 0. A., IXD.ENG.CHEM.,29, 805 (1937). Chilton, T. H., and Colburn, A. P., Ibid., 26, 1183 (1934). Ibid., 27, 255 (1935). Colburn, A.P.,Trans. Am. Inst. Chem. Engrs., 35, 211 (1939). Davis, H. S.,Thomson, G., and Crandall, G . S., J. Am. Chem. Soc., 54, 2340 (1932). Gilliland, E. R., and Sherwood, T. K., IND.ENG.CHEM.,26, 516 (1934). Hatta, S., Tech. Repts. TBhoku Imp. Univ., 8, 1 (1928-29). Johnstone, H. F., and Singh, A. D., IND.ENG.CHEM.,29, 286 (1937). Lewis, W. K., and Radasoh, A. H., “Industrial Stoichiometry”, preface, New York, McGraw-Hill Book Co., 1926. London, Mason, and Boelter, Trans. Am. SOC.Mech. Engrs., 61, 41 (1940). Sherwood, T. K., Trans. Am. Inst. Chem. Engrs., 36, 817 (1940). Sherwood, T. K.,and Holloway, F. A. L., Ibid., 36, 39 (1940). Sherwood, T. K., and Reed, C. E., “Applied Mathematics in Chemical Engineering”, p. 134, New York, McGraw-Hill Book Co., 1939.
Tu, C. M., Davis, H., and Hottel, H. C., IND.ENG.CHEM.. 26, 749 (1934).
Walker, W. H., Lewis, W. K., and McAdams, W. H., “Principles of Chemical Engineering”, 1st ed., New York, McGrawHill Book Co., 1923. Ibid.. 2nd ed.. 1927. Whitman, W.’G., Chem. & Met. Eng., 29, 146 (1923).
