Page 103 - Adsorption, Ion Exchange & Catalysis- 2007, Elsevier - Copy

Else_AIEC-INGLE_cH003.qxd 7/13/2006 1:45 PM Page 99
3.3 T w Reactors o-Phase Agitated 99

For the rest of the parameters, SI units are used. For the evaluation of density difference,
the hydraulic density for the solid phase is used:

)( ) (3.115)
(1
h L p s L
where:
the particle porosity
p
the skeletal density of the solid.
s
The parameter S is called the proportionality constant or shape f and depends on the , actor
impeller and vessel geometry (Armenante and Nagamine, 1998):

D   s 2  C 
S s 1  T  exp s 3  b  (3.116)
D    D 
a T
where C b is the impeller clearance measured from the bottom of the impeller to the bottom
of the tank, in m. The constants s depend upon the type of the impeller and for c , ylindrical
i
baffled vessels, are presented in T1998). able 3.5 (Armenante and Nagamine,
These values were obtained for 1/48 C / D T 1/2.5. The of alues v S gi en by McCabe v
b
v directly for seeral types of impellers (McCabe et al ., 1993) are shoT able 3.6. wn in

Table 3.5
Constants of parameter S .
Impeller type s s s
1 2 3
Flat blade disc turbine with six blades 0.99 1.4 2.18
Straight blade open turbine with six blades 1.43 1.2 1.95
Pitched-blade (45°) turbine with six blades 2.28 0.83 0.65
Fluidfoil Chemineer HE-3 impeller 3.49 0.79 0.66

Table 3.6
Value of the shape factor S .

Impeller type D / D D / Z S
T a T a
Flat-blade disc turbine with six blades ( D / W 5, N 6.2) 2 4 4.1
a p
3 4 7.5
Paddle with two blades ( D / W 4, N 2.5) 2 4 4.8
a p
3 4 8
4 4 12.5
Propeller with three blades ( N 0.5) 3 4 6.5
p
4 4 8.5
4 2.5 9.5