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3.4 Slurry Reactors 127

In the case of continuous flow of both phases, the liquid phase can be considered well
mixed if (Ramachandran and Chaudhari, 1980)

 ud sL p  Z  
 D     4 (3.205)
LL  p d  

Gas phase For the gas-phase dispersion coefficient, the Field and Da vidson equation is
proposed (Koide, 1995):

D 19.7 D u 2 (3.206)
LG sG
SI units are used with this correlation.

3.4.8 External mass transfer

Mass transfer coeficients: liquid to particle (k f f )
Gogoi and Dutta (1996) studied the solid–liquid mass transfer in a three-phase spar ged
reactor. They derived the following correlation:

kd  ud  0.1094 
 0.45
f p T p L L
    (3.207)
2 0.21
D f 
L   L D f 
The liquid-phase turb which enhances the particle–liquid drag force thereby
ulence,
icient,
increasing the value of the masstransfer coef is characterized by the turb ulence
f
intensity ( u ), as defined by the following relation:
T
     13


u 0.49 gD u  sG  h u h u s L  (3.208)
T G b S sh    
   L  
 h  3.5
u u 1.1 0.026 u 0.8 L (3.209)
sh sG ter  1  h  
G

g ( d ) 2
u ter s L p (3.210)
18
L

where:
u T the turbulence intensity (in m/s)
u b the bubble rising v elocity