Page 254 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

I I I II Nrovity tfling of Spheres in Still 'luid
Commercial
article General Common Methods Equipment for pheres
ameter Classification of Measuring Collection or ny Densi Critical Particle Diameter
, Any Flu
Particol Size Removal of - Laws of Settling Above Which Law Will Not
icrons eynold Apply
a Gas lumber
i -NRe-
~0,000. I 100,oc
I I )p,crit 'Kcr [ P2 1'
5- I I I Newton's Law
-I in. - I 9LP (Ps- P)
2 I : I I
I
10,000 = cm. I 8
-41n.- -_ I I I Kcr -2,360 for Newton's Law
-I.
5

- 500
Intermediate Law Kcr = 43.5 for
C = 18.5 NR;,0'6 Intermediate Law
0.1 53 g ,"'" Dp '"4(psp)0.
Ut =
P0.'9P 0.43
-2.0
Stoke s' Law Kcr -33 far Stokes' Law
C 2 24 NR;'

0.000 he Cunningham Correction on Stokes'
Stokes-Cunningham Law .ow Becomes Importmt far Particles
if Diameters Under 3 Microns for
jettling in Gases ond Under 0.01
Ut ' Km ~ t s
4icron for Settling in Liquids.
K, ;I+Kme (Xm/Op)
257-278r193311. An Approximate Average Volue Based on the Data of
Millikon is Empirically Given by
Kme =1.644+0.552e-(0.656 Dp/Xm)
Brownian Movement Brownian Movement is 0 Random
Motion Superimposed upon the
lx d4gc the Particle it Becomes Appreciobe
Grovitotionoi Settling Velocity of
for Particles under 3 Microns
3r2p
Diameter and Becomes Entirely
N
RTKm
Dp
Predominant for Porticles Under
0.1 Micron.
+
5
t - :I
-; "I '
"
I
?S
01-
2 --ou S I
JO I
-0.001 - I 2 V I 0.001 -
7 C 2 Overall Drog Coefficient, Dimensionless ,NRc: Reynolds Nurnber,Dimensianless =Dppp ~/p
Dp = Diameter of Spherical Particle,tt. Gas Canstant,1,546(ft.-lb.Force) (Ib. mole)("F)
From Kinetic Theory of Gases: Dp crlt =Critical Porticle Diometer Above Which Law I :Time ,sec.
will Not Apply, ft. T =Absolute Gas Temperature ,OF abs.,ar OR
x, '3plp v g, =Conversion Factor,3~.l7Llb.moss/Ib. Force)/ ut = Terminol Settling Velocity of Particle Under
( ft. /sec I
Action of Grovity ,ft./sec.
J : d m g, Locol Accelerofion due to Grovity,lftl/lsec) uts =Terminal Settling Velocity of Particle os
Calculated from Stokes' Low , ft./sec.
(sec.1
KC, = Proportionality Factor , Dimensionless 7 =Meon Moleculor Speed, ft./sec.
K, = Stokes-Cunningham Correction Foctor, Ax = Averoge Linear Amplitude or Displocement of
Dimensionless Porticle in Time t,ft.
Kme : Proportionalify Foctor, Dimensionless p =Fluid Density , Ib. moss/cu. It.
M = Moiecuior Weight, lb./mole ps =True Density of Particle, Ib mass/cu.ft
N : Number ot Gos Molecules in o mole, p =Fluid Viscosity,llb. massl/(tl.)(sec.)
2 76 x IOs Halecules/Ib. mole Xm :Meon Free Polh of Gos Molecules,ft.
Figure 4-1. Characteristics of dispersed particles. By permission, Perry, J. H., Ed., Chemical Engineers Handbook, 3rd. Ed., 1950, McGraw-
Hill Company, Inc.