Page 46 - Plant design and economics for chemical engineers

PROCESS DESIGN DEVELOPMENT 29

Use a 10°F temperature difference for the cooling water to find the mass of
cooling water required to remove the heat of reaction.
Q, 211,500
-=-
m HZ0 = cp AT (lj(loj = 21,150 lbih

21,150
%(H,O) = @,)@33) = 42*3 wrn

The volumetric flow rate is, therefore, 42.3 gpm. Select a 45gpm centrifugal
pump, carbon steel construction.

HEAT TRANSFER AREA NEEDED TO COOL REACTOR Assume water inlet of
80°F with a 10°F temperature rise. A reasonable overall heat transfer coefficient
for this type of heat transfer may be calculated as 45 Btu/(hXft*X“F).
AT = (115 - 80) - (115 - 90) =29 7"F
Im 2.303 log $$

Q 211,500
A=-=
u AT,, (45)(29.7) = 158ft2
A 1300-gal stirred reactor has approximately 160 ft* of jacket area. Therefore,
the surface area available is sufficient to maintain isothermal conditions in the
reactor.

SIZING OF STORAGE TANKS. Provide benzene and dodecene storage for six
days:
Vbenzene = (1670)( 6) = 10,020 gal
Vddecene = (4160) (6) = 24,960 gal
Select a lO,OOO-gal carbon steel tank for benzene storage and a 25,000-gal
carbon steel tank for dodecene storage.
Provide holding tank storage for one day:
I/holding = 5918 gal

Select a 6000-gal carbon steel tank for holding tank.
SIZING OTHER PUMPS. Provide benzene and dodecene filling of reactor in 10
min:
1670
4f@enzene) = ~ = 27.8 gpm
(WW
Select a 30-gpm centrifugal pump, carbon steel construction.
4160
= - = 69.3 gpm
qf(dodecene)
(6)(10)