Pharmaceutical Manufacturing Handbook: Production and

150 EFFECT OF SCALE-UP ON OPERATION OF JACKETED REACTORS
where ̇m n the is the nozzle mass fl ow rate, v n is the nozzle velocity, the friction factor
is
the jacket - side fi lm coeffi cient is
h
j
f = × 2 0. 023
02 Re .
kj
08 033
= 0. 027Rej Prj
D
and the Reynolds and Prandtl numbers are
e
Dv e jρj Rej =
μ
c
Prj =
k
μ
j
j pj
j
(31)
. . (32)
Overall Coeffi cient The overall heat transfer coeffi cient is found from the sum of
the resistances,
(33)
(34)
1 1 1 xm
xg
= + + + + ffi + ffj
(35)
U h h k k
i j
which includes reactor fi lm, jacket fi lm, vessel metal, vessel glass, and fouling factors
for both the reactor and jacket sides.
3.1.4.2 Effect of Reactor Type, Jacket Heat Transfer Fluid, and Reactor
Fluid Viscosity
m
Here we present examples of how the reactor type and heat transfer fl uid affect the
heat transfer coeffi cient. When the reactor fl uid has a low viscosity, the dominant
heat transfer resistance tends to be on the jacket side. When the reactor fl uid has a
high viscosity, however, the dominant resistance is typically on the reactor side.
Parameter values for the studies are presented in Figures 5 – 7 and are given in the
literature [18] .
The overall heat transfer coeffi cient is much higher for an alloy reactor/half - pipe
jacket than for a glass - lined carbon steel reactor/agitation nozzle jacket, as shown
in Figure 5 , where Syltherm is the heat transfer fl uid. Syltherm has a signifi cantly
lower heat transfer coeffi cient than an ethylene glycol mixture, as shown in Figure
6 , but is capable of operating over a wider range of temperatures. The reactor fl uid
viscosity has a tremendous effect on the overall heat transfer coeffi cient, as shown
in Figure 7 . This can be particularly important in polymerization reactions where
viscosity increases with conversion.
g