Page 559 - Elements of Chemical Reaction Engineering Ebook

Chap. Ei Questions and Problems 529

are carried out in a perfectly insulated CSTR. The desired reaction is first order
in A and zero order in B, while the undesired reaction is zero order in A and
first order in B. The feed rate is equimolar in A and B. Species A enters the
reactor at a temperature of 100°C and species B enters at a temperature of 50°C.
The operating temperature of the reactor is 400 K. The molar flow rate of A
entering the reactor is 60 mol/min: Cp, = 20 cal/mol. K, Cp, = 30 cal/mol. K,
Cp, = 50 cal/mol*K, and CPu = 40 cal/mol.K.
For reaction 1: AH,, = -3000 cal/mol of A at 300 K
For reaction 2: AHRx = -5000 callmol of A at 300 K
i 2Yl
k, = 1000 exp - - min-]

mol
<
C,, = 0.01 mol/dm3 0.001 - C,,<2 mol/dm3
dm3
(a) What will be the exit molar flow rates of TJ and D from the reactor?
(b) What is the CSTR reactor volume for the conditions specified above?
(c) Is there a more effective way to maximize D? Explain.
(Hint: Start with a mole balance on A. Outline your method before beginning
any calculations.)
PS-32, The liquid phase reactions
A k,A B k2B >C

B k3B > D
can be carried out in a number of CSTRs. Currently, the following sizes are
available, 4 dm3, 40 dm3, 400 dm3, 4000 dm3. ‘You can use up to 4 CSTRs of
any one size. The heat flow to each reactor is controled by adjusting the func-
tional area f(0 5 f < 1 .O).
Q, = lOOf(T - T,) (callmin) where the ambient temperature can be
varied between 0°C and 100°C.

7000(J--!) .
k,, = 0.3e 300 rnin-I
7000(1-1)
k,, = 0.03e 3w * min-]
4000 (J- - L)
k3B = 0.1e 300 dmj/mol.min
The Concentration of pure A is 5 M. A can be diluted with solvent. The feed
can be cooled to 0°C or heated to 100°C.
AHRxlA = + 10,000 cal/mol A
AHRx2B = - 10,000 cal/mol B
AHRx3B = - 100,000 caUmol B