Page 556 - Elements of Chemical Reaction Engineering Ebook

526 Steady-State Nonisothermal Reactor Design Chap. 8

A k'>B k2)C

The feed conditions and desired product specifications are known, together with
the temperature of the heating medium. It is your job to design the reactor, that
is, to specify the reactor volume and the area of the heating coil inside the reactor.
(a) Calculate the desired operating temperature inside the reactor. (Ans.: 269°F.)
(b) Calculate the volume of the reactor. (Am: 6.58 ft3.)
(c) Calculate the area of the heating coil. (Am: 18.1 fp.)
(d) Find a set of conditions that will give multiple steady states if reaction 1
is exothermic rather than endothermic. How many steady states can you
find? (Am: 5.) Make a plot of G(T) vs. R(T) and of T, vs. To.

Additional irlformation:
Product:
The ratio C,/C, is equal to 10.
50% of A in the feed is converted.

Feed:
The feed is gas-phase and pure A.
The molar flow rate is 0.05 Ib mol/&
The volumetric flow rate is 7.85 ft3/s.
The temperature is 400°F.
The pressure in the reactor is 4 atm.

Heat capacities:
Cp's of A, B, Ad C are all 25 Btu/lb rnol."F.
Reaction 1: Reaction 2:
A, = 2x 109 s-1 A, = 1 X lo1* s-l
E, = 31,000 Btu/lb mol E, = 40,000 Btu/lb mol
AHRxl = 15,000 Btu/lb mol A reacted AHRx2 = -20,000 Btu/lb mol C reacted
Heat transfer:
The heating medium is saturated high-pressure steam at 350°F.
The overall heat-transfer coefficient between the heating medium
and the reaction mixture is 400 Btu/h.ft2*"F.
(Multiple reactions with heat effects) Xylene has three major isomers,
rn-xylene, o-xylene, and p-xylene. When o-xylene is passed over a Cryotite
catalyst, the following elementary reactions are observed:

Application fl (Q
Pending CH3
for Problem
Hall of 6LH3 ci"
Fame k3 ' 0