Ideal Flow Reactors - Bioprocess Engineering: Kinetics, Biosystems, Sustainability and Reactor Design - page 251

respectively. Determine themaximumfractional conversion ( f A ) obtainedat the outlet and
order of reactors if the three CSTR's available of volume: 10 L, 20 L, and 50 L.
5.33. When B is mixed A, the liquid phase reaction

A þ B / C r ¼ kC A

0.2 min 1 . This reaction is to be carried out isothermally in
a CSTR at steady state. The reactant A costs $2/mol and reactant B costs $0.10/mol.
The product C sells for $6/mol. The cost of operating the reactor is $0.05 per liter per
hour. We wish to produce 360,000 mol of C per day to meet the market demands.
The available reactants: A and B, are from different sources: the solution for A has
a concentration of 1 mol/L and the solution for B has a concentration of 4 mol per liter.
Assume no cost or value to dispose off unreacted A and B.
(a) What is the overall feed stream concentration of A if a stoichiometric feed is chosen?
Is this the best choice and why?
(b) Perform a mole balance on the reactor to relate the conversion of Awith the reactor
size.
(c) Express the profit per mole of A feed to the reactor as a function of the conversion.
(d) What is the optimum conversion of A (for a stoichiometric feed) and what is the
corresponding reactor size?
(e) What is the cash flow (or profit per mole of A feed to the reactor) from the process?
5.34. The reaction between ammonia and formaldehyde to give hexamine is

Has a rate constant k

¼

CH 2 Þ 6 N 4 þ 6 H 2 O
A 0.5-L CSTR is used for the reaction. Each reactant is fed to the reactor in a separate
stream, at the rate of 1.5

4 NH 3 þ 6 HCHO / ð

10 3 L/seachwithammoniaconcentration4.0mol/L
and formaldehyde 6.4 mol/L. The reactor temperature is 36 C. Calculate the
concentration of ammonia and formaldehyde in the effluent stream. The reaction
rate is

mol-A
L

r A ¼ kC A C B

s

where A is ammonia and B is formaldehyde
k ¼ 1:42 10 3 exp 3090 K
T

5.35. The reaction A D is carried out in an adiabatic plug flow reactor. The

following data are available

þ B # C þ

= mol K

DH R ¼120; 000 J = mol C r A ¼ C r B ¼ C r C ¼ C r D ¼ 100 J

;

50 o C

K e ð equilibrium constant Þ¼500; 000 at

min
Calculate the maximum conversion that may be achieved if the feed enters at 27 C and
only A and B are in the feed.

F A 0 ¼ F B 0 ¼ 10 mol =