CL 351                                   Homework # 12

 

No Due date, work out the solutions for end semester exam

 

1.       We have 100 kg/hr of a feed that is 60% methylcyclohexane and 40% n-heptane and 50 kg/hr of a feed that is 20% methylcycloheane and 80% n-heptane.  These two feeds are mixed with 200 kg/hr of pure aniline in a single equilibrium stage or a mixer-settler arrangement.  What are extract and raffinate compositions leaving the stage?  What is the flow rate of extract product?  Equilibrium data is given below.

 

2.       We wish to remove acetic acid from water using isopropyl ether as solvent.  The operation is at 20oC and 1 atm.  Equilibrium data is given below.  The feed is 0.45 weight fraction acetic acid and 0.55 weight fraction water.  Feed flow rate is 2000 kg/hr.  A countercurrent system is used.  Pure solvent is used.  We desire an extract stream that is 0.2 weight fraction acetic acid and a raffinate that is 0.2 weight fraction acetic aicd.  How much solvent is required?  How many equilibrium stages or mixer-settler arrangements are required?  Find flow rates of extract and raffinate streams leaving stage to which solvent is fed.

 

3.       A pyridine-water solution, 50 wt% pyridine, is to be continuously and countercurrently extracted at the rate of 2.25 kg/sec with pure chlorobenzene to reduce the pyridine concentration to 2 wt%.   Determine the minimum solvent rate required.  If 2.3 kg/sec of solvent is used, calculate the flow rates of final extract and raffinate streams.

 

Data for Problem 1:

 

              Hydrocarbon Phase,

Methylcyclohexane,

xA

wt%

n-heptane, xD

            Aniline-rich phase

Methylcyclohexane,

yA

wt%

n-heptane,

yD

0

92.6

0

6.2

9.2

83.1

0.8

6

18.6

73.4

2.7

5.3

22

69.8

3.0

5.1

33.8

57.6

4.6

4.5

4.9

50.4

6.0

4.0

46.0

45.0

7.4

3.6

59.0

30.7

9.2

2.8

67.2

22.8

11.3

2.1

71.6

18.2

12.7

1.6

73.6

16.0

13.1

1.4

83.3

5.4

15.6

0.6

88.1

0

16.9

0

 

 

  Data for Problem 2:

 

 

                    

 

Acetic acid

xA

Water layer

 

water

xD

wt%

 

Isopropylether

xS

 

           

 

Acetic acid,

yA

Isopropylether

 

water,

yD

layer, wt%

 

Isopropylether

yS

0.69

98.1

1.2

0.18

0.5

99.3

1.41

97.1

1.5

0.37

0.7

98.9

2.89

95.5

1.6

0.79

0.8

98.4

6.42

91.7

1.9

1.93

1.0

97.1

13.3

84.4

2.3

4.82

1.9

93.3

25.5

71.1

3.4

11.4

3.9

84.7

36.7

58.9

4.4

21.6

6.9

71.5

44.3

45.1

10.6

31.1

10.8

58.1

46.4

37.1

16.5

36.2

15.1

48.7

 

 

Data for Problem 3:

 

 

                    

 

water

 

Chlorobenzene

 

chlorobenzene

 

Phase, wt%

 

pyridine

 

 

           

 

water

Water phase,

 

chlorobenzene

wt%

 

pyridine

0.05

99.95

0

99.92

0.08

0

0.67

88.28

11.05

94.82

0.16

5.02

1.15

79.9

18.95

88.71

0.24

11.05

1.62

74.28

24.10

80.72

0.38

18.90

2.25

69.15

28.60

73.92

0.58

25.50

2.87

65.58

31.55

62.05

1.85

36.10

3.95

61.00

35.05

50.87

4.18

44.95

3.4

53.00

40.60

37.90

8.90

53.20

13.2

37.80

49.00

13.20

37.80

49.00