Page 135 - Adsorption, Ion Exchange & Catalysis- 2007, Elsevier - Copy

Else_AIEC-INGLE_cH003.qxd 7/13/2006 1:45 PM Page 131
3.5 Agitated Slurry Reactors 131

In mass-transfer correlations, the volumetric mass-transfer coeficient is expressed using f
the gas–liquid interfacial area per unit volume of slurry (or expanded column or reactor ,
V R ) (Koide, 1996; Kantarci et al ., 2005; NTIS, 1983):

A bubbles,tota l d 2 n d 2 n 6
a t GL,to bub bub h G h G
V V     d 3  d (3.229)
R G bub bub
 h    n 
G   6 
a GL,tot GL L a h (3.230)

Note that from the correlation of Hikita et al . (1981),

ka fg GL,tot sG u
f k a fg GL,tot
g
(3.231)
fg a GL fg a GL
ka fg GL,tot
u sG a GL,to t u ssG a t GL,to
or
fg 1
ka fg GL (3.232)
u sG h L

where

u 
 1.76 
4 g  0.248 
 0.24 3 3 
 0.604
L
G
3 
f 14.9   sG
L L    
  
    D L fg   (3.233)
L
L
L
L
3.5 AGITATED SLURRY REACTORS

3.5.1 Agitated slurry reactor models

In CSTR reactors, both phases are considered to be in complete mixed and continuous-
flow condition. In the general case where reactants can be gases and liquids, the follo wing
material balances can be applied (for simplicity we consider constant-density systems)
(Hopper et al ., 2001)
v Liquid reactant (nonolatile component) liquid-phase mass balance:

Q L
C ( L,i C L,o ) k a( c C )( L,o C S ) 0 (3.234)
f
V
L