1. Exercise 2 solution Lecturer: Miss Anis Atikah Ahmad

2. Questions X 0.2 0.4 0.45 0.5 0.6 0.8 0.9 -rA (mol/dm3.min 1.0 1.67 5.0
The exothermic reaction A--->B + C was carried out adiabatically and the following data recorded: The entering molar flow rate of A was 300 mol/min. (a) What are the PFR and CSTR volumes necessary to achieve 40 % conversion? (b) Over what range of conversions would the CSTR and PFR reactor volumes be identical? (c) What is the maximum conversion that can be achieved in a 105 dm3 CSTR? (d) What conversion can be achieved if a 72 dm3 PFR is followed in series by a 24 dm3 CSTR? (e) What conversion can be achieved if a 24 dm3 CSTR is followed in a series by a 72 dm3 PFR? X
0.2
0.4
0.45
0.5
0.6
0.8
0.9
-rA (mol/dm3.min
1.0
1.67
5.0
1.25
0.91

3. Part (A)
What are the PFR and CSTR volumes necessary to achieve 40 % conversion?
PFR Volume:
Using Simpson One-Third Rule;
Recall Simpson One-Third Rule Formula:

4. Part (A) X 0.2 0.4 0.45 0.5 0.6 0.8 0.9 -rA (mol/dm3.min) 1.0 1.67 5.0
0.2
0.4
0.45
0.5
0.6
0.8
0.9
-rA (mol/dm3.min)
1.0
1.67
5.0
1.25
0.91
FA0/-rA (dm3)
300
180 60
240
330
Levelspiel Plot
VPFR

5. Part (a) CSTR Volume: Substituting the value of FA0/–rA at X=0.4;
VCSTR
Levelspiel Plot

6. The volume of both reactors are identical at X=0.4-0.6,
Part (B)
Over what range of conversions would the CSTR and PFR reactor volumes be identical?
From Levelspiel Plot;
The volume of both reactors are identical at X= ,

7. Using Simpson One-Third Rule
Part (B)
Over what range of conversions would the CSTR and PFR reactor volumes be identical?
Proving by calculation;
Volume of PFR
Using Simpson One-Third Rule
Volume of CSTR

8. Part (c)
What is the maximum conversion that can be achieved in a 105 dm3 CSTR?
By trial and error, calculate what is X that gives a CSTR volume of 105 dm3 Trial 1: X=0.6,
Trial 2: X=0.8,
Trial 3: X=0.7,
X=0.7
The max conversion can be achieved in 105 dm3 of CSTR is 0.7

9. Now, we know that the conversion must be between 0.6-0.7.
Part (d)
What conversion can be achieved if a 72 dm3 PFR is followed in series by a 24 dm3 CSTR?
FA0=300 mol/dm3
X1=0.4
From part (a)
VPFR=72 dm3
VCSTR=24 dm3
By trial and error, calculate what is X2 that gives a CSTR volume of 24 dm3 Trial 1: X2=0.6, Trial 2: X2=0.7,
X2=?
Now, we know that the conversion must be between

10. Part (d)
What conversion can be achieved if a 72 dm3 PFR is followed in series by a 24 dm3 CSTR?
FA0=300 mol/dm3
X1=0.4
VPFR=72 dm3
VCSTR=24 dm3
Trial 3: X2=0.64,
X2=?
X=0.64
X=0.64 can be achieved if a 72 dm3 PFR is followed in series by a 24 dm3 CSTR.

11. Part (e)
What conversion can be achieved if a 24 dm3 CSTR is followed in a series by a 72 dm3 PFR?
FA0=300 mol/dm3
From part (a)
VCSTR=24 dm3
X1=0.4
VPFR=72 dm3
X2=?
By trial and error, calculate what is X2 that gives a PFR volume of 72 dm3 Trial 1: X2=0.8,

12. Part (e)
What conversion can be achieved if a 24 dm3 CSTR is followed in a series by a 72 dm3 PFR?
FA0=300 mol/dm3
VCSTR=24 dm3
X1=0.4
VPFR=72 dm3
X2=?
By trial and error, calculate what is X2 that gives a PFR volume of 72 dm3 Trial 2: X2=0.9,

13. Part (e)
What conversion can be achieved if a 24 dm3 CSTR is followed in a series by a 72 dm3 PFR?
Trial 3: X2=0.91,
X=0.91 can be achieved if a 24 dm3 CSTR is followed in a series by a 72 dm3 PFR

14. THANK YOU