Ideal Flow Reactors - Bioprocess Engineering: Kinetics, Biosystems, Sustainability and Reactor Design - page 219

The final concentrations for the products are:

C Re ¼ S R = A n 1 R

n 1 A ðC A 0 C Ae Þ¼1:716 mol

= L

and
C Qe ¼ð1 S R = A Þ n 2Q

n 2 A ðC A 0 C Ae Þ¼7:284 mol

=

L

2. CSTR
Figure E5-7.1 shows a sketch of the CSTR. One can find the parameters already known
as f A ¼ 0.9, C A0 ¼ C B0 ¼ 10 mol/L, C A ¼ C B ¼ (1 0.9) 10 mol/L ¼ 1 mol/L. The

selectivity of product R is given by

k 1 C A
k 1 C A þ k 2 C 1=2

1
3

S R = A ¼ s R = A ¼ ¼ (E5-7.8)

B

The product stream concentration can be computed as

C Re ¼ S R = A n 1 R

n 1 A ðC A 0 C Ae Þ¼3 mol

= L

n 2 A C A 0 C Ae ¼ 6 mol

C Qe ¼ð1 S R = A Þ n 2Q = L

3. From Eqn (E5-7.3) , we infer that the higher the concentration of A and the lower the
concentration of B in the reactor will give the highest selectivity to the desired product R. In
this case, feeding A from the beginning will render the highest concentration of A available
to participate in the reaction. The lowest concentration of B achievable is the concentration
at the end of the reactor. Therefore, Fig. E5-7.1 c will give the highest selectivity to R.

In this case, the volumetric flow rate Q and the concentration of A are changing in the
reactor, while the concentration of B is desired to be constant that equals to the concentration

F B0
Q B

F A0

Q A

C A

C B

Q C A

C B

f Ae

FIGURE E5-7.1 A schematic of a CSTR with two feed streams.