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3.7 Three-Phase Fixed Beds: Trickle-Bed and Ped Bubble-Bed Reactors ack 181

1

0.8

0.6

w
f
0.4
5 ) fw ( mm, 1 g/ml, 1cP
1 fw (0 mm, 1 g/l, 1cP m )
0.2
1 m ) fw (0 mm, 2 g/l, 1 cP
m fw (10 mm, 2 g/l, 0.5 cP )
0
0.1 1 10 100 1000
Re L
Figure 3.48 The effect of particle size, liquid density and liquid dynamic viscosity on wetting
,
efficiency.

In Figure 3.49, the minimum liquid superficial velocity versus particle size in order to
have a wetting efficiency higher than 90% for water as liquid phase at 25 °C is presented.
For the typical case of water systems used in environmental applications, e.g. remo v al
of SO 2 from gas streams, the minimum superficial velocity of water for a wetting ef f i-
ciency higher than 90% v.s. can be correlated to particle size as follo ws:

u 0.141 d 0.486 (3.413)
s p
where u is in cm/s and d p is in mm. At high pressure, the correlation reported by
s
Al-Dahhan et al . (1995) can be used (W 1996): u,
 1[ PZ) ( g)]  19
(
f 1.104 Re 13  L  (3.414)
w L
 Ga L 
The Reynolds number is based on superficial velocity and SI units are used. Another
correlation is that of Bur ghardt et al . (1995):

f 3.38 Re 0.222 Re Ga 0.083 * 0.512 (3.415)
w L G L
where
d p
Ga * Ga 13 (3.416)
L 2 2 13

 L ( L g )  