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Else_AIEC-INGLE_cH003.qxd 7/13/2006 1:45 PM Page 145
3.6 T ed Beds o-Phase Fix w 145

where F is the molar flow rate in mole per unit time:

F u A s (3.294)
QC
C
e, v In the forms presented abo the material balance is expressed in moles per time per unit
volume of reactor V R (see Section 3.1.1 for deri v ation):

1d N V V M
( R ) S ( r vs ) L ( r ) u ( S ) r m (3.295)
V d t V V V
R R R R

For fixed beds,
V
L (3.296)
V
R
V V V
V

1 L R L S (3.297)
1
V V V
R R R
M
S (3.298)
b
V
R
Then, the oerall rate of the reaction v –R per unit volume of reactor is
1d N
( R ) (1 ) r vs ( r ) u ( ) m r (3.299)
)(
b
V d t
R
or using the other definitions of rate,
(
V R ( V ) r ( V ) r ( M) r ) (3.300)
R S vs L u S m

Energy balance equation
The general balance equation for an unsteady-state fixed-bed operation is (Ruthven, 1984;
Froment and Bischof 1990) f,

 T f 2 T f   2 T f T f 
  c f pf , z L z 2   R   r 2 r r  
u
s
4 h  T T s  (3.301)
R )) H ( T f T w ) c  ,f p f f c bps , 
(
D  t t 