~~~
~~~
Table II. Vessel Shape Power Factors for Six-Blade Open-Style Turbine
WID Installation
DIT
Horizontal cylindrical tank, 5 :1
0.4
Square tank
= 1/8
Impellm Location
Center mounted
0.4
Vertical Bajj7es Location
‘Vumber
None (2) T/10
Center mounted T/4 eccentric mounted Center mounted
To indicate clearly the typical behavior of the three styles of turbines, Figure 7 shows the Power number for the ordinate rather than a power factor. For direct use as a geometric factor in Equation 1, the ratio of the N p value for a specific condition to the N p value a t “standard” conditions-Le., C/ T = l / g c a n be used. For the disk turbine, since the suction is partitioned by the disk, there is a marked reduction in power as clearance is decreased. T h e flat open-style six-blade turbine ( w / D = l / ~ ) displays a variable effect a t different clearances, but in general a slightly higher power level a t lower values of C/D. Increasing the proximity of a 45’ pitched open-style sixblade turbine (w/D = l / ~ ) ,as expected, increases power consumption. T h e data of Miller and M a n n (9) note a reduction in power rather than a n increase, but their data were taken in a n unbaffled system and thus a r e not comparable.
DISC TYPE
I
None None (4) TI10 (2) T/10
T w
wb Z
= = = =
Factor
... ...
0.75 1 .o 1. o 1 .o
90”, wall center 180°, wall center
tank diameter impeller blade width baffle width liquid depth
GREEKLETTERS
e
= angle of impeller blade from horizontal
p p
= viscosity = density
SUBSCRIPTS 1 = condition 1 2 = condition 2 EXPONENTS = a, b ,
G,
etc.
literature Cited
(1) Bates, R. L., Ind. Eng. C h m . 51, 1245 (1959). (2) Bissell, E. S., Hesse, H . C., Everett, H. J., Rushton, J. H., Chem. Eng. Progr. 43, 649 (1947). (3) Calderbank, P. H., Trans. Inst. Chem. Engrs. 36, 443 (1958). (4) Hixson, A. W., Baum, S. J.. Ind. Eng. Chem. 34, 194 (1942). (5) Hixson, A. W., Luedeke, V. C., Ibid., 29, 927 (1937). (6) Johnstone, R. E., Thring, M. W., “Pilot Plants, Models and Scale-up Methods in Chemical Engineering,” McGraw-Hill, New York. 1957. (7) Lee, R. E., Finch, C. R., Wooledge, J. D.. Ind. Eng. Chem. 49, 1849 (1957). (8) Mack, D. E., Kroll, A. E., Chem. Eng. Progr. 44,189 (1948). (9) Miller, S. A., Mann, C. A.. Trans. A.I.CI1.E. 40, 709 (1944). (10) Nanata. S.. Yokovama., T.,, Mem. Fac. Ene., Kyoto Unzv. , ‘ (Japm,”17, ’253’(195 5) .‘ (11) Nagata, S., Yokoyama, T., Maeda, H., Ibid., 18, 13 (1956). (12) O’Connell, F. D., Mack, D. E., Chem. Eng. Aogr. 46, 358, (1950). (13) Rushton, J. H., Costich, E. W.,Everett. H J.. Ibzd., 46, 395 (1950). (14) Ibid., b. 467. (15) Unwin, W. C.: Proc. Roy. Sac. (London) A31, 54 (1880). (16) Van de Vusse, J. G.. Chem. Eng. Sci.4, 178, 209 (1955). (17) White, A. M.: Brenner, E., Trans. A.Z.Ch.E. 30, 585 (1934). (18) White, A. M., Brenner, E.: Phillips, G. L4.,Morrison, M. S., Ibid., 30, 570 (1934). (19) White, A. M., Somerford, S. D., Chem. M e f . Eng. 43, 370 (1936). I
I ’ 01
, 02
03
04
CLEARANCE RATIO
Figure 7.
06 +
OB
10
I 20
C/D
Effect of turbine proximity on power
Nomenclature
C
off tank bottom, measured from underside of impeller D = impeller diameter g, = gravitational constant o r conversion factor K = constant 1 = blade length n = number of impeller blades nb = number of baffles .V = impeller speed, r.p.m. ArFp= Froude number N p = Power number NRe= Reynolds number = blade pitch = power S = impeller spacing
.
RECEIVED for review December 31, 1962 ACCEPTED June 10, 1963 A.1.Ch.E. Meeting, Chicago, Ill., December 1962.
= impeller distance
PP
314
1. o 1 .O
D/4 distance, ‘180’ longitudinal axis
I h E C PROCESS D E S I G N A N D D E V E L O P M E N T
Correction
THE KINETICS OF NICKEL CARBONYL FOR MATION I n this article by M‘. M. Goldberger and D . F. O t h m e r [IND. E N G . CHEM.PROCESSDESIGNAND DEVELOP.2, 202 (1 963) 1, on page 209, reference 8 should read : Othmer, D . F.. Luley, .4.H.. Ind. Eng.Chem. 38,408 (1946).
