Page 191 - Adsorption, Ion Exchange & Catalysis- 2007, Elsevier - Copy

Else_AIEC-INGLE_cH003.qxd 7/13/2006 1:46 PM Page 187
3.7 Three-Phase Fixed Beds: Trickle-Bed and Ped Bubble-Bed Reactors ack 187

s Gas–liquid mass transfer in pacubble bed r ed b eactor k
f The gas–liquid mass transfer coeficient is given by Reiss correlation (Ramachandran and
Chaudhari, 1984):
3  P  0.5
ka 5.48 10 u sL  GL  (3.432)
fg GL  Z 

In this equation, CGS units should be used.

eactor s Liquid–solid mass transfer in trickle-bed r
A correlation of Dharwadkar and Sylvester is suitable for trickle beds in the region 0.2
Re L 2400 (Perry and Green, 1999; Smith, 1981):

 D g  23
ka fL S 1.637 a u R L e L 0.331   L
L   (3.433)
u s
where:
D g the dificient of gas in the liquid-phase f fusion coef
k f the liquid–solid mass transfer coeficient in m/s f
a u the total external area of particles per unit volume of reactor .
SI units should be used in this equation. The following correlations were proposed by
Fogler (1999):

dk pf
for Re 60 : L 0.815 Re Sc 0.8 L 1 3 (3.434)
D fg

dk pf
for Re 20 : L 0.266 Re 1.15 L Sc 1 3 (3.435)
D fg

ed b s Liquid–solid mass transfer in pacubble bed r k eactor
f
The liquid–solid mass transfer coeficient is gien by the Mochizuki–Matsui correlation v
(Ramachandran and Chaudhari, 1984):
for Re L < 5,
kd u  d  0.25
fp e sG G pe
48   (3.436)
D 

fg G
where
2
d d (3.437)
pe p
3 1