chapter iii level 1 ayda baru

CHAPTER III

PRODUCTION DESIGN CONCEPT

3.1 PROCESS OVERVIEW

There are two reactions involved in production of acrylonitrile which can be either

done in one single multi-functional catalyst which promotes direct routes for both

reactions or with two different catalysts which involved two coupled reactors for

indirect route.

The process involved only one reactor which is direct ammoxidation of

glycerol is constructed in an experimental scale to trace the desired product,

acrylonitrile (Banares et al. 2008). It is found that there was only 2% of selectivity

where the main product being carbon dioxide in about 50%. In addition, there are also

other problems which related to the catalyst and condition. The catalyst for the first

reaction is dehydration which exhibits acidity while ammonia which is basic also

presence in the feed. This will probably block the acidic of the catalyst used for

dehydration. Besides, the temperature ranges for both reactions are difference, which

is 300oC for first reaction and 350oC for second reaction. Others, the feed need to be

purified glycerol, not crude glycerol which will be used in this design project.

Presence of impurities in the feed will negatively affect selectivity of acrylonitrile.

The unreacted glycerol in the reactor will decompose under reaction conditions

(temperature 400°C) and form a coke, which will result in deactivation of

ammoxidation catalysts.

51

Hence, due to the considerations have made, our plant is designed on the

indirect routes where two reactors are used. The first reactor involved the catalytic

dehydration of glycerol in gaseous phase and the produced acrolein can be separated

from water, impurities and side products formed via a separation unit. This way, the

feed into the second reactor will be purer in formed and result in higher acrylonitrile

selectivity.

3.2 PROCESS DESIGN LEVEL 1

Hierachy design process for conceptual design is developed by Douglas (1988). The

design involved five stages where economic feasibility is used as main criterion for

process evaluation at every stage. Level one included all chemical reaction and its

stochiometry, information of the design process namely raw material and product

physical and chemical properties of component involved. Design constraint is also

determined in this level (Wan Ramli 2002).

3.2.1 Chemical Reaction

The production of oxalic acid in the plant involved two main reactions. The first

reaction occurs in batch reactor in form of hydrolyzer where cellulose from sugarcane

bagasse will be converted into its simpler form which is glucose. Acid sluphuric acid

will be used in assisting the process of breaking down cellulose to glucose.

The second reaction which is the main reaction is the oxidation of carbohydrate with

nitric acid. Glucose will react with nitric acid with the help of vanadiumpenta-oxide as

a catalyst. The reaction will produce oxalic acid, and a by-product nitrogen oxide, also

with the unreacted raw material. The by product formed, nitrogen oxide will be further

treated before it’s released.

52

a) Reaction Stoichiometry

Reaction at first reactor

C12H 20O10 + 2H 2O 2C6H 12O6 (3.1)

(cellucose) (water) (glucose)

Reaction at second reactor

C6H 12O6 + 6HNO3 3[COOH ]2.6H 2O + 6NO

(3.1)(glucose) (nitric acid) (oxalic acid) (nitrogen oxide)

A symbol is assigned to address each compound according to their name. The symbol

is used in the following equations and calculations.

Cellulose = C

Glucose = G

Nitric Acic = NA

Oxalic Acid = OA

Nitrogen Oxide = NO

b) Reaction Conditions

For the biomass pre-treatment, the hydrolysis reaction occur at the temperature of

160°C and pressure of 5.5 bar where the water quantity added to the reactor was

calculated considering the prehydrolyzed bagasse moisture content to produce a solid

to liquid ratio of 1:13. The cellulose will be converted to glucose in about 70 minutes

(Vinícius et al. 2012).

For oxidation proccess, the reaction is carried out at the temperature of 71°C and

pressure of 3.5 bar. Glucose will be oxidised where it takes two oxygen molecule from

nitric acid assisted by the vanadiumpenta-oxide catalyst. The reaction should be

rigidly controlled between the temperature of 62.8°C to 85°C. At temperature below

H 2SO4

V 2O5

53

62.8°C, the reaction proceeds too slow meanwhile at the temperature above 85°C, the

yield of oxalic acid tends to decline drastically (Watson and Fuchs 1970).

c) Kinetic Rate Law

Assumptions:

1) Reaction is a first order reaction

2) All reactions occur at liquid phase

3) Reaction of first reactor at 433.15K at 5.5 bar while reaction at second

reactor occurs at 344.15K at 3.5 bar pressure.

4) Reaction occur isothermally where T = To and reactor volume is constant.

5) No pressure drop of reaction where P = Po

−r A=k C ACB

Rate of reaction for each equation is as follows

r1 = k1 CC CW2 (3.5)

r2 = k2 CG CNA6 (3.6)

The net rate law of reaction each species as follows,

Cellulose : rC = -r1 (3.9)

Water : RW = -2r1 (3.10)

Glucose : RG = 2r1- r2 (3.11)

Nitric acid : rNA = -6r2 (3.12)

Oxalic acid : rOA = 3r2 (3.13)

Nitrogen oxide : rNO = 6r2 (3.14)

54

d) Selectivity Versus Conversion

The reaction to produce oxalic acid takes place in packed bed reactor since a solid in

form catalyst is to be used. For this type of reactor, the differential form of the design

equation is as below:

dXdW

=−rGFG 0

Equation 3.18 to 3.26 are written in term of conversion as follow,

Glycerol : dFGdX

=rG ( -

FGorG

¿= -FGO (3.18)

Acrolein : dF ACdX

=rAC ( -

FGorG

¿=

(−r1+r3

−r1−r2

¿ FGO

(3.19)

Acetaldehyde : dF ADdX

=rAD ( -

FGorG

¿=

(−r2+r4

−r1−r2

¿ FGO

(3.20)

Acetonitrile : dF ATNdX

=rATN ( -

FGorG

¿=

(r4

r1+r2

¿ FGO

(3.21)

Formaldehyde : dFFDdX

=rFD ( -

FGorG

¿=

(r2

r1+r2

¿ FGO

(3.22)

Acrylonitrile : dF ACNdX

=rACN ( -

FGorG

¿=

(r3

r1+r2

¿ FGO

(3.23)

Ammonia : dF AMdX

=rAM ( -

FGorG

¿=

(r3+r4

−r1−r2

¿ FGO

(3.24)

Oxygen : dFOdX

=rO ( -

FGorG

¿=

(

12r3+

12r

4

−r1−r2

¿ FGO

(3.25

Water : dFWdX

=rW ( -

FGorG

¿=

(−2 r1−r2−2 r3−2r 4

−r1−r2

)

(FGO

(3.26)

For concentration of each substance, each substance can be written in terms of flow

where

Total flowrate at any time, t is

55

FT = FG + FAC + FAD + FATN + FFD + FACN + FAM + FO + FW

Cellulose : CC = FCFT

x CT

(3.27)

Water : CW = FWFT

x CT

(3.28)

Glucose : CG = FGFT

x CT

(3.29)

Nitric acid : CNA = F NAFT

x CT

(3.30)

Oxalic acid : COA = FOAFT

x CT

(3.31)

Nitrogen oxide : CNO = F NOFT

x CT

(3.32)

Selectivity of each compenent,

Water : SW = FWFC X

(3.37)

Glucose : SG = FGFC X

(3.38)

Nitric acid : SNA = F NAFC X

(3.39)

Oxalic acid : SOA = FOAFC X

(3.40)

Nitrogen oxide : SNO = FNOFC X

(3.41)

Equations from 3.5 to 3.43 are solved using ODE solver in Polymath Software using

Runge- Kutta algorithm with the following assumptions and data obtained.

FGO = 100 kmol/dm3.min

56

k1 = 4.4 x 10-1

k2 = 6.9 x 10-2

k3 = 7.8 x 10-2

k4 = 9.8 x 10-5

Source: Makoto Akizuki et. al 2012

By using the ODE solver which is polymath, a profile of molar flow rate against

conversion and selectivity is acquired.

Differential equations

1 d(Fg)/d(X) = Rg*(-Fg0/Rg)

2 d(Fac)/d(X) = Rac*(-Fg0/Rg)

3 d(Fad)/d(X) = Rad*(-Fg0/Rg)

4 d(Fatn)/d(X) = Ratn*(-Fg0/Rg)

5 d(Ffd)/d(X) = Rfd*(-Fg0/Rg)

6 d(Facn)/d(X) = Racn*(-Fg0/Rg)

7 d(Fam)/d(X) = Ram*(-Fg0/Rg)

8 d(Fo)/d(X) = Ro*(-Fg0/Rg)

9 d(Fw)/d(X) = Rw*(-Fg0/Rg)

Explicit equations

1 k1 = 4.4*10^(-1)

2 Ct = 10

3 Ft = Fg+Fac+Fad+Fatn+Ffd+Facn+Fam+Fo+Fw

4 Cg = (Fg/Ft)*Ct

5 k4 = 9.8*10^(-2)

6 k3 = 7.8*10^(-2)

7 k2 = 6.9*10^(-2)

8 r1 = k1*Cg

9 Cam = (Fam/Ft)*Ct

57

10 Co = (Fo/Ft)*Ct

11 r2 = k2*Cg

12 Cac = (Fac/Ft)*Ct

13 Cad = (Fad/Ft)*Ct

14 Catn = (Fatn/Ft)*Ct

15 Cfd = (Ffd/Ft)*Ct

16 Cacn = (Facn/Ft)*Ct

17 r3 = k3*Co^(1/2)*Cam*Cac

18 r4 = k4*Co^(1/2)*Cam*Cad

19 Cw = (Fw/Ft)*Ct

20 Fg0 = 100

21 Rg = -r1-r2

22 Rac = r1-r3

23 Rad = r2-r4

24 Ratn = r4

25 Rfd = r2

26 Racn = r3

27 Ram = -r3-r4

28 Ro = (-1/2)*r3+(-1/2)*r4

29 Rw = 2*r1+r2+2*r3+2*r4

30 Sac = Fac/(Fg0-Fg+0.0001)

31 Sad = Fad/(Fg0-Fg+0.0001)

32 Satn = Fatn/(Fg0-Fg+0.0001)

33 Sfd = Ffd/(Fg0-Fg+0.0001)

34 Sacn = Facn/(Fg0-Fg+0.0001)

35 Sw = Fw/(Fg0-Fg+0.0001)

Figure 3.1 Equations entered into Polymath

General

Total number of equations 44

58

Number of differential equations 9

Number of explicit equations 35

Elapsed time 0.000 sec

Solution method RKF_45

Step size guess. h 0.000001

Truncation error tolerance. eps 0.000001

Calculated values of DEQ variables

Variable Initial value Minimal value Maximal value Final value

1 Cac 0 0 0.9568288 0.2125577

2 Cacn 0 0 1.377456 1.377456

3 Cad 0 0 0.1371584 0.0203684

4 Cam 3.333333 0.2329261 3.333333 0.2329261

5 Catn 0 0 0.2289747 0.2289747

6 Cfd 0 0 0.2545464 0.2493431

7 Cg 3.333333 3.454E-10 3.333333 3.454E-10

8 Co 3.333333 1.036141 3.333333 1.036141

9 Ct 10. 10. 10. 10.

10 Cw 0 0 6.642232 6.642232

11 Fac 0 0 45.72643 11.55609

12 Facn 0 0 74.88792 74.88792

13 Fad 0 0 6.43472 1.107366

14 Fam 100. 12.66345 100. 12.66345

15 Fatn 0 0 12.44863 12.44863

16 Ffd 0 0 13.55599 13.55599

17 Fg 100. 1.878E-08 100. 1.878E-08

18 Fg0 100. 100. 100. 100.

59

19 Fo 100. 56.33173 100. 56.33173

20 Ft 300. 300. 543.6683 543.6683

21 Fw 0 0 361.1171 361.1171

22 k1 0.44 0.44 0.44 0.44

23 k2 0.069 0.069 0.069 0.069

24 k3 0.078 0.078 0.078 0.078

25 k4 0.098 0.098 0.098 0.098

26 r1 1.466667 1.52E-10 1.466667 1.52E-10

27 r2 0.23 2.383E-11 0.23 2.383E-11

28 r3 0 0 0.2254846 0.003931

29 r4 0 0 0.0423765 0.0004733

30 Rac 1.466667 -0.0439473 1.466667 -0.003931

31 Racn 0 0 0.2254846 0.003931

32 Rad 0.23 -0.007613 0.23 -0.0004733

33 Ram 0 -0.2678069 0 -0.0044042

34 Ratn 0 0 0.0423765 0.0004733

35 Rfd 0.23 2.383E-11 0.23 2.383E-11

36 Rg -1.696667 -1.696667 -1.758E-10 -1.758E-10

37 Ro 0 -0.1339035 0 -0.0022021

38 Rw 3.163333 0.0088085 3.163333 0.0088085

39 Sac 0 0 0.853614 0.1155607

40 Sacn 0 0 0.7488785 0.7488785

41 Sad 0 0 0.1334327 0.0110736

42 Satn 0 0 0.1244861 0.1244861

43 Sfd 0 0 0.1355598 0.1355598

44 Sw 0 0 3.611167 3.611167

45 X 0 0 1. 1.

Figure 3.2: Result of polymath

60

Figure 3.3 Molar flowrate of each components as a function of conversion of glycerol

Table 3.1 Polymath Polynomial Regression Migration Data (Flowrates)

X Fg Fac Fad Fatn Ffd Facn Fam Fo Fw

0 100 0 0 0 0 0 100 100 0

0.0270

04

97.299

64

2.3051

53

0.3603

3

0.0057

31

0.3660

61

0.0291

49

99.965

12

99.982

56

5.1044

24

0.0350

04

96.499

64

2.9769

95

0.4649

09 0.0096

0.4745

09

0.0488

59

99.941

54

99.970

77

6.6431

34

0.0430

04

95.699

64

3.6438

4

0.5685

12

0.0144

45

0.5829

57

0.0735

66

99.911

99

99.955

99

8.1937

9

0.0510

04

94.899

64

4.3057

25

0.6711

47

0.0202

58

0.6914

05

0.1032

32

99.876

51

99.938

25

9.7563

01

0.0670

04

93.299

64

5.6147

54

0.8735

5

0.0347

51

0.9083

01

0.1773

08

99.787

94

99.893

97

12.916

54

61

0.0750

04

92.499

64

6.2619

66

0.9733

35

0.0434

14

1.0167

49

0.2216

49

99.734

94

99.867

47

14.514

1

0.0830

04

91.699

64

6.9043

53

1.0721

86

0.0530

11

1.1251

96

0.2708

13

99.676

18

99.838

09

16.123

18

0.0910

04

90.899

64

7.5419

49

1.1701

11

0.0635

33

1.2336

44

0.3247

69

99.611

7

99.805

85

17.743

69

0.1070

04

89.299

64

8.8028

92

1.3632

17

0.0873

23

1.4505

4

0.4469

31

99.465

75

99.732

87

21.018

69

0.1150

04

88.499

64 9.4263

1.4584

12

0.1005

76

1.5589

88

0.5150

75

99.384

35

99.692

17

22.673

04

0.1230

04

87.699

64

10.045

04

1.5527

13

0.1147

23

1.6674

36

0.5878

89

99.297

39

99.648

69

24.338

51

0.1310

04

86.899

64

10.659

14

1.6461

25

0.1297

59

1.7758

84

0.6653

43

99.204

9

99.602

45

26.015

05

0.1470

04

85.299

64

11.873

52

1.8303

14

0.1624

66

1.9927

8

0.8340

66

99.003

47

99.501

73

29.401

01

0.1550

04

84.499

64

12.473

85

1.9211

04

0.1801

24

2.1012

28

0.9252

81

98.894

59

99.447

3

31.110

31

0.1630

04

83.699

64

13.069

65

2.0110

32

0.1986

43

2.2096

76

1.0210

32

98.780

32

99.390

16

32.830

4

0.1710

04

82.899

64

13.660

94

2.1001

06

0.2180

18

2.3181

24

1.1212

94

98.660

69

99.330

34

34.561

22

0.1870

04

81.299

64

14.830

08

2.2757

13

0.2593

07

2.5350

2

1.3352

59

98.405

43

99.202

72

38.054

84

0.1950

04

80.499

64

15.407

98

2.3622

57

0.2812

1

2.6434

68

1.4489

19

98.269

87

99.134

94

39.817

52

0.2030

04

79.699

64

15.981

44

2.4479

69

0.3039

46

2.7519

16

1.5670

04

98.129

05

99.064

53

41.590

71

0.2110

04

78.899

64

16.550

51

2.5328

55

0.3275

09

2.8603

63

1.6894

92 97.983

98.991

5

43.374

36

0.2270

04

77.299

64

17.675

49

2.7001

65

0.3770

94

3.0772

59

1.9476

12

97.675

29

98.837

65

46.972

88

0.2350 76.499 18.231 2.7825 0.4031 3.1857 2.0832 97.513 98.756 48.787

62

04 64 45 99 08 07 1 68 84 65

0.2430

04

75.699

64

18.783

06

2.8642

25

0.4299

31

3.2941

55

2.2231

46

97.346

92

98.673

46

50.612

72

0.2510

04

74.899

64

19.330

35

2.9450

46

0.4575

57

3.4026

03

2.3674

06

97.175

04

98.587

52

52.448

05

0.2670

04

73.299

64

20.412

01

3.1042

92

0.5152

07

3.6194

99

2.6688

5

96.815

94

98.407

97

56.149

34

0.2750

04

72.499

64

20.946

4

3.1827

24

0.5452

24

3.7279

47

2.8260

12

96.628

76

98.314

38

58.015

25

0.2830

04

71.699

64

21.476

51

3.2603

65

0.5760

3

3.8363

95

2.9874

55

96.436

52

98.218

26

59.891

3

0.2910

04

70.899

64

22.002

35

3.3372

19

0.6076

24

3.9448

43

3.1531

7

96.239

21

98.119

6

61.777

47

0.3070

04

69.299

64

23.041

23

3.4885

75

0.6731

63

4.1617

39

3.4973

97

95.829

44

97.914

72

65.580

11

0.3150

04

68.499

64

23.554

28

3.5630

83

0.7071

04

4.2701

87

3.6758

98 95.617

97.808

5

67.496

54

0.3230

04

67.699

64

24.063

07

3.6368

11

0.7418

23

4.3786

35

3.8586

56

95.399

52

97.699

76

69.423

05

0.3310

04

66.899

64

24.567

61

3.7097

64

0.7773

19

4.4870

83

4.0456

68

95.177

01

97.588

51

71.359

62

0.3470

04

65.299

64

25.563

92

3.8533

42

0.8506

36

4.7039

78

4.4324

61

94.716

9

97.358

45

75.262

94

0.3550

04

64.499

64

26.055

69

3.9239

71

0.8884

56

4.8124

26

4.6322

49

94.479

3

97.239

65

77.229

71

0.3630

04

63.699

64

26.543

18

3.9938

26

0.9270

48

4.9208

74

4.8363

03

94.236

65

97.118

32

79.206

55

0.3710

04

62.899

64

27.026

41

4.0629

08

0.9664

15

5.0293

22

5.0446

33

93.988

95

96.994

48

81.193

5

0.3870

04

61.299

64

27.979

99

4.1987

5

1.0474

68

5.2462

18

5.4741

53

93.478

38

96.739

19

85.197

75

0.3950

04

60.499

64

28.450

33

4.2655

09

1.0891

57

5.3546

66

5.6953

67

93.215

48

96.607

74

87.215

11

63

0.4030

04

59.699

64

28.916

34

4.3314

91

1.1316

23

5.4631

14

5.9209

04

92.947

47

96.473

74

89.242

66

0.4110

04

58.899

64

29.378

02

4.3966

95

1.1748

67

5.5715

62

6.1507

79

92.674

35

96.337

18

91.280

45

0.4270

04

57.299

64

30.288

28

4.5247

61

1.2636

97

5.7884

58

6.6236

23

92.112

68

96.056

34

95.386

91

0.4350

04

56.499

64

30.736

82

4.5876

18

1.3092

88

5.8969

06

6.8666

36

91.824

08

95.912

04

97.455

67

0.4430

04

55.699

64

31.180

93

4.6496

85

1.3556

68

6.0053

54

7.1140

77

91.530

25

95.765

13

99.534

86

0.4510

04

54.899

64

31.620

59

4.7109

6

1.4028

41

6.1138

02

7.3659

74

91.231

19

95.615

59

101.62

46

0.4670

04

53.299

64

32.486

4

4.8311

17

1.4995

81

6.3306

97

7.8832

6

90.617

16

95.308

58

105.83

57

0.4750

04

52.499

64

32.912

5

4.8899

88

1.5491

57

6.4391

45

8.1487

2

90.302

12

95.151

06

107.95

73

0.4830

04

51.699

64

33.333

99

4.9480

48

1.5995

46

6.5475

93

8.4187

76

89.981

68

94.990

84

110.08

98

0.4910

04

50.899

64

33.750

85

5.0052

89

1.6507

52

6.6560

41

8.6934

7

89.655

78

94.827

89

112.23

31

0.5070

04

49.299

64

34.570

47

5.1172

9

1.7556

47

6.8729

37

9.2569

57

88.987

4

94.493

7

116.55

3

0.5150

04

48.499

64

34.973

12

5.1720

35

1.8093

51

6.9813

85

9.5458

53

88.644

8

94.322

4

118.72

97

0.5230

04

47.699

64

35.370

94

5.2259

3

1.8639

03

7.0898

33

9.8395

91

88.296

51

94.148

25

120.91

79

0.5310

04

46.899

64

35.763

85

5.2789

68

1.9193

13

7.1982

81

10.138

23

87.942

46

93.971

23

123.11

75

0.5470

04

45.299

64

36.534

7

5.3824

28

2.0327

48

7.4151

77

10.750

48

87.216

77

93.608

38

127.55

2

0.5550

04

44.499

64

36.912

5

5.4328

29

2.0907

96

7.5236

25

11.064

24

86.844

97

93.422

48

129.78

72

0.5630 43.699 37.285 5.4823 2.1497 7.6320 11.383 86.467 93.233 132.03

64

04 64 11 27 46 73 18 07 54 45

0.5710

04

42.899

64

37.652

45

5.5309

08

2.2096

13

7.7405

21

11.707

4

86.082

99

93.041

5

134.29

42

0.5870

04

41.299

64

38.370

93

5.6252

64

2.3321

52

7.9574

17

12.372

02

85.295

83

92.647

92

138.85

16

0.5950

04

40.499

64

38.721

88

5.6710

08

2.3948

57

8.0658

64

12.712

62

84.892

52

92.446

26

141.14

98

0.6030

04

39.699

64

39.067

16

5.7157

71

2.4585

41

8.1743

12

13.058

89

84.482

57

92.241

28

143.46

13

0.6110

04

38.899

64

39.406

65

5.7595

36

2.5232

25

8.2827

6

13.410

96

84.065

82

92.032

91

145.78

63

0.6270

04

37.299

64

40.067

75

5.8439

88

2.6556

68

8.4996

56

14.132

95

83.211

38

91.605

69

150.47

83

0.6350

04

36.499

64

40.389

1

5.8846

3

2.7234

74

8.6081

04

14.503

16

82.773

36

91.386

68

152.84

59

0.6430

04

35.699

64

40.704

1

5.9241

85

2.7923

67

8.7165

52

14.879

71

82.327

92

91.163

96

155.22

83

0.6510

04

34.899

64

41.012

59

5.9626

24

2.8623

76 8.825

15.262

77

81.874

85

90.937

43

157.62

6

0.6670

04

33.299

64

41.609

36

6.0360

44

3.0058

51

9.0418

96

16.049

1

80.945

04

90.472

52

162.46

87

0.6750

04

32.499

64

41.897

25

6.0709

61

3.0793

83

9.1503

44

16.452

77

80.467

85

90.233

92

164.91

47

0.6830

04

31.699

64

42.177

85

6.1046

37

3.1541

55

9.2587

92

16.863

72

79.982

13

89.991

06

167.37

77

0.6910

04

30.899

64

42.450

94

6.1370

33

3.2302

07

9.3672

4

17.282

18

79.487

61

89.743

81

169.85

83

0.7070

04

29.299

64

42.973

56

6.1978

2

3.3863

16

9.5841

36

18.142

66

78.471

02

89.235

51

174.87

45

0.7150

04

28.499

64

43.222

54

6.2261

19

3.4664

64

9.6925

84

18.585

24

77.948

3

88.974

15

177.41

16

0.7230

04

27.699

64

43.462

88

6.2529

56

3.5480

76

9.8010

31

19.036

46

77.415

47

88.707

73

179.96

88

65

0.7310

04

26.899

64

43.694

24

6.2782

73

3.6312

06

9.9094

79

19.496

65

76.872

15

88.436

07

182.54

7

0.7470

04

25.299

64

44.128

53

6.3241

04

3.8022

71

10.126

38

20.445

46

75.752

27

87.876

13

187.76

98

0.7550

04

24.499

64

44.330

61

6.3444

8

3.8903

43

10.234

82

20.934

92

75.174

73

87.587

37

190.41

64

0.7630

04

23.699

64

44.522

04

6.3630

61

3.9802

1

10.343

27

21.435

05

74.584

74

87.292

37

193.08

8

0.7710

04

22.899

64

44.702

29

6.3797

61

4.0719

58

10.451

72

21.946

35

73.981

69

86.990

84

195.78

56

0.7870

04

21.299

64

45.026

88

6.4071

34

4.2614

81

10.668

61

23.004

87

72.733

65

86.366

83

201.26

48

0.7950

04

20.499

64

45.169

89

6.4175

89

4.3594

74

10.777

06

23.553

41

72.087

12

86.043

56

204.04

94

0.8030

04

19.699

64

45.299

05

6.4257

24

4.4597

87

10.885

51

24.115

81

71.424

41

85.712

2

206.86

64

0.8110

04

18.899

64

45.413

47

6.4313

99

4.5625

6

10.993

96

24.692

93

70.744

51

85.372

25

209.71

77

0.8270

04

17.299

64

45.594

19

6.4347

2

4.7761

35

11.210

85

25.895

32

69.328

54

84.664

27

215.53

28

0.8350

04

16.499

64

45.658

17

6.4319

9

4.8873

12

11.319

3

26.522

89

68.589

79

84.294

9

218.50

18

0.8430

04

15.699

64

45.702

77

6.4260

42

5.0017

09

11.427

75

27.169

84

67.828

45

83.914

23

221.51

61

0.8510

04

14.899

64

45.726

43

6.4166

17

5.1195

82

11.536

2

27.837

74

67.042

68

83.521

34

224.57

92

0.8670

04

13.299

64

45.703

32

6.3861

12

5.3669

82

11.753

09

29.243

95

65.389

07

82.694

54

230.86

95

0.8750

04

12.499

64

45.652

01

6.3642

93

5.4972

49

11.861

54

29.986

81

64.515

94

82.257

97

234.10

73

0.8830

04

11.699

64

45.570

48

6.3374

96

5.6324

94

11.969

99

30.759

9

63.607

61

81.803

8

237.41

55

0.8910 10.899 45.455 6.3051 5.7732 12.078 31.566 62.660 81.330 240.80

66

04 64 29 65 73 44 64 09 05 21

0.9070

04

9.2996

37

45.106

45

6.2210

75

6.0742

59

12.295

33

33.298

58

60.627

16

80.313

58

247.85

11

0.9150

04

8.4996

37

44.861

43

6.1674

9

6.2362

92

12.403

78

34.235

15

59.528

56

79.764

28

251.53

98

0.9230

04

7.6996

37

44.559

3

6.1045

97

6.4076

33

12.512

23

35.228

84

58.363

53

79.181

77

255.36

14

0.9310

04

6.8996

37

44.189

73

6.0307

46

6.5899

32

12.620

68

36.289

95

57.120

12

78.560

06

259.33

98

0.9470

04

5.2996

37

43.188

23

5.8405

95

6.9969

79

12.837

57

38.674

56

54.328

47

77.164

23

267.90

62

0.9550

04

4.4996

37

42.510

17

5.7169

7

7.2290

51

12.946

02

40.044

17

52.726

78

76.363

39

272.60

12

0.9630

04

3.6996

37

41.663

27

5.5663

15

7.4881

54

13.054

47

41.582

62

50.929

22

75.464

61

277.68

78

0.9710

04

2.8996

37

40.578

78

5.3778

25

7.7850

92

13.162

92

43.358

66

48.856

25

74.428

12

283.32

53

0.9831

27

1.6872

74

38.155

2

4.9690

26

8.3582

4

13.327

27

46.830

27

44.811

49

72.405

75

293.67

52

0.9904

31

0.9568

72

35.726

13

4.5715

58

8.8547

21

13.426

28

49.890

72

41.254

56

70.627

28

302.15

09

1

1.88E-

08

11.556

09

1.1073

66

12.448

63

13.555

99

74.887

92

12.663

45

56.331

73

361.11

71

Table 3.2 Polymath polynomial regression mitigation data (Selectivity)

X Sac Sad Satn Sfd Sacn Sw

0 0 0 0 0 0 0

0.0270

04

0.8536

14

0.1334

33

0.0021

22

0.1355

55

0.0107

94

1.8902

04

0.0350 0.8504 0.1328 0.0027 0.1355 0.0139 1.8977

67

04 58 14 43 56 58 88

0.0430

04

0.8473

14

0.1321

98

0.0033

59

0.1355

57

0.0171

06

1.9053

28

0.0510

04

0.8441

83

0.1315

86

0.0039

72

0.1355

57

0.0202

4

1.9128

27

0.0670

04

0.8379

65

0.1303

72

0.0051

86

0.1355

58

0.0264

62

1.9277

09

0.0750

04

0.8348

77

0.1297

7

0.0057

88

0.1355

58

0.0295

51

1.9350

94

0.0830

04

0.8318

03

0.1291

72

0.0063

87

0.1355

58

0.0326

26

1.9424

43

0.0910

04

0.8287

44

0.1285

77

0.0069

81

0.1355

58

0.0356

87

1.9497

56

0.1070

04

0.8226

65

0.1273

98

0.0081

61

0.1355

59

0.0417

67

1.9642

79

0.1150

04

0.8196

45

0.1268

13

0.0087

45

0.1355

59

0.0447

87

1.9714

89

0.1230

04

0.8166

39

0.1262

32

0.0093

27

0.1355

59

0.0477

94

1.9786

66

0.1310

04

0.8136

46

0.1256

54

0.0099

05

0.1355

59

0.0507

88

1.9858

11

0.1470

04

0.8076

97

0.1245

07

0.0110

52

0.1355

59

0.0567

37

2.0000

06

0.1550

04

0.8047

41

0.1239

39

0.0116

21

0.1355

59

0.0596

94

2.0070

57

0.1630

04

0.8017

97

0.1233

73

0.0121

86

0.1355

59

0.0626

38

2.0140

78

0.1710

04

0.7988

64

0.1228

1

0.0127

49

0.1355

59

0.0655

71

2.0210

7

0.1870

04

0.7930

33

0.1216

93

0.0138

66

0.1355

59

0.0714

03

2.0349

68

0.1950

04

0.7901

34

0.1211

39

0.0144

21

0.1355

59

0.0743

02

2.0418

76

68

0.2030

04

0.7872

45

0.1205

87

0.0149

72

0.1355

59

0.0771

91

2.0487

57

0.2110

04

0.7843

67

0.1200

38

0.0155

21

0.1355

59

0.0800

69

2.0556

12

0.2270

04

0.7786

4

0.1189

48

0.0166

12

0.1355

59

0.0857

96

2.0692

48

0.2350

04

0.7757

91

0.1184

06

0.0171

53

0.1355

59

0.0886

46

2.0760

3

0.2430

04

0.7729

51

0.1178

67

0.0176

92

0.1355

59

0.0914

86

2.0827

88

0.2510

04

0.7701

19

0.1173

3

0.0182

29

0.1355

59

0.0943

17

2.0895

25

0.2670

04

0.7644

82

0.1162

64

0.0192

96

0.1355

59

0.0999

55

2.1029

35

0.2750

04

0.7616

75

0.1157

34

0.0198

26

0.1355

59

0.1027

62

2.1096

1

0.2830

04

0.7588

75

0.1152

05

0.0203

54

0.1355

59

0.1055

62

2.1162

66

0.2910

04

0.7560

83

0.1146

79

0.0208

8

0.1355

6

0.1083

55

2.1229

03

0.3070

04

0.7505

17

0.1136

33

0.0219

27

0.1355

6

0.1139

2

2.1361

28

0.3150

04

0.7477

44

0.1131

12

0.0224

47

0.1355

6

0.1166

94

2.1427

16

0.3230

04

0.7449

76

0.1125

93

0.0229

66

0.1355

6

0.1194

61

2.1492

9

0.3310

04

0.7422

14

0.1120

76

0.0234

84

0.1355

6

0.1222

24

2.1558

5

0.3470

04

0.7367

03

0.1110

46

0.0245

14

0.1355

6

0.1277

35

2.1689

32

0.3550

04

0.7339

54

0.1105

33

0.0250

27

0.1355

6

0.1304

84

2.1754

56

0.3630 0.7312 0.1100 0.0255 0.1355 0.1332 2.1819

69

04 08 21 38 6 3 71

0.3710

04

0.7284

66

0.1095

11

0.0260

49

0.1355

6

0.1359

72

2.1884

77

0.3870

04

0.7229

89

0.1084

94

0.0270

66

0.1355

6

0.1414

49

2.2014

66

0.3950

04

0.7202

53

0.1079

86

0.0275

73

0.1355

6

0.1441

85

2.2079

52

0.4030

04

0.7175

19

0.1074

8

0.0280

8

0.1355

6

0.1469

19

2.2144

33

0.4110

04

0.7147

86

0.1069

74

0.0285

85

0.1355

6

0.1496

52

2.2209

11

0.4270

04

0.7093

2

0.1059

65

0.0295

94

0.1355

6

0.1551

18

2.2338

61

0.4350

04

0.7065

86

0.1054

61

0.0300

98

0.1355

6

0.1578

52

2.2403

36

0.4430

04

0.7038

51

0.1049

58

0.0306

02

0.1355

6

0.1605

87

2.2468

13

0.4510

04

0.7011

15

0.1044

55

0.0311

05

0.1355

6

0.1633

24

2.2532

93

0.4670

04

0.6956

34

0.1034

49

0.0321

11

0.1355

6

0.1688

05

2.2662

67

0.4750

04

0.6928

88

0.1029

46

0.0326

14

0.1355

6

0.1715

5

2.2727

64

0.4830

04

0.6901

38

0.1024

43

0.0331

17

0.1355

6 0.1743

2.2792

7

0.4910

04

0.6873

84

0.1019

4

0.0336

2

0.1355

6

0.1770

55

2.2857

86

0.5070

04

0.6818

57

0.1009

32

0.0346

28

0.1355

6

0.1825

81

2.2988

55

0.5150

04

0.6790

84

0.1004

27

0.0351

33

0.1355

6

0.1853

55

2.3054

11

0.5230

04

0.6763

03

0.0999

21

0.0356

38

0.1355

6

0.1881

36

2.3119

85

70

0.5310

04

0.6735

13

0.0994

15

0.0361

45

0.1355

6

0.1909

26

2.3185

77

0.5470

04

0.6679

05

0.0983

98

0.0371

61

0.1355

6

0.1965

34

2.3318

27

0.5550

04

0.6650

85

0.0978

88

0.0376

72

0.1355

6

0.1993

54

2.3384

88

0.5630

04

0.6622

52

0.0973

76

0.0381

84

0.1355

6

0.2021

86

2.3451

76

0.5710

04

0.6594

07

0.0968

63

0.0386

97

0.1355

6

0.2050

32

2.3518

94

0.5870

04

0.6536

73

0.0958

3

0.0397

3

0.1355

6

0.2107

65

2.3654

27

0.5950

04

0.6507

83

0.0953

1

0.0402

49

0.1355

6

0.2136

56

2.3722

47

0.6030

04

0.6478

75

0.0947

88

0.0407

72

0.1355

6

0.2165

64

2.3791

07

0.6110

04

0.6449

48

0.0942

63

0.0412

96

0.1355

6

0.2194

9

2.3860

1

0.6270

04

0.6390

34

0.0932

05

0.0423

55

0.1355

6

0.2254

04

2.3999

55

0.6350

04

0.6360

44

0.0926

71

0.0428

89

0.1355

6

0.2283

95

2.4070

04

0.6430

04

0.6330

3

0.0921

33

0.0434

27

0.1355

6

0.2314

09

2.4141

09

0.6510

04

0.6299

89

0.0915

91

0.0439

69

0.1355

6

0.2344

5

2.4212

73

0.6670

04

0.6238

24

0.0904

95

0.0450

65

0.1355

6

0.2406

15

2.4357

96

0.6750

04

0.6206

96

0.0899

4

0.0456

2

0.1355

6

0.2437

43

2.4431

64

0.6830

04

0.6175

34

0.0893

79

0.0461

81

0.1355

6

0.2469

05

2.4506

08

0.6910 0.6143 0.0888 0.0467 0.1355 0.2501 2.4581

71

04 37 13 47 6 02 35

0.7070

04

0.6078

26

0.0876

63

0.0478

97

0.1355

6

0.2566

13

2.4734

57

0.7150

04

0.6045

07

0.0870

78

0.0484

82

0.1355

6

0.2599

32

2.4812

64

0.7230

04

0.6011

42

0.0864

86

0.0490

74

0.1355

6

0.2632

97

2.4891

78

0.7310

04

0.5977

29

0.0858

86

0.0496

74

0.1355

6

0.2667

1

2.4972

06

0.7470

04

0.5907

4

0.0846

6 0.0509

0.1355

6

0.2736

99

2.5136

37

0.7550

04

0.5871

57

0.0840

32

0.0515

27

0.1355

6

0.2772

82

2.5220

57

0.7630

04

0.5835

1

0.0833

95

0.0521

65

0.1355

6

0.2809

3

2.5306

26

0.7710

04

0.5797

93

0.0827

46

0.0528

14

0.1355

6

0.2846

46

2.5393

57

0.7870

04

0.5721

3

0.0814

12

0.0541

48

0.1355

6

0.2923

09

2.5573

52

0.7950

04

0.5681

72

0.0807

24

0.0548

36

0.1355

6

0.2962

68

2.5666

44

0.8030

04

0.5641

19

0.0800

21

0.0555

39

0.1355

6

0.3003

2

2.5761

55

0.8110

04

0.5599

66

0.0793

02

0.0562

58

0.1355

6

0.3044

73

2.5859

01

0.8270

04

0.5513

17

0.0778

08

0.0577

52

0.1355

6

0.3131

22

2.6061

86

0.8350

04

0.5468

01

0.0770

29

0.0585

3

0.1355

6

0.3176

38

2.6167

74

0.8430

04

0.5421

41

0.0762

28

0.0593

32

0.1355

6

0.3222

98

2.6276

97

0.8510

04

0.5373

23

0.0754

01

0.0601

59

0.1355

6

0.3271

16

2.6389

89

72

0.8670

04

0.5271

4

0.0736

57

0.0619

03

0.1355

6

0.3372

99

2.6628

4

0.8750

04

0.5217

34

0.0727

34

0.0628

25

0.1355

6

0.3427

05

2.6754

98

0.8830

04

0.5160

84

0.0717

72

0.0637

88

0.1355

6

0.3483

55

2.6887

23

0.8910

04

0.5101

58

0.0707

65

0.0647

95

0.1355

6

0.3542

81

2.7025

91

0.9070

04

0.4973

12

0.0685

89

0.0669

71

0.1355

6

0.3671

27

2.7326

33

0.9150

04

0.4902

86

0.0674

04

0.0681

56

0.1355

6

0.3741

53

2.7490

55

0.9230

04

0.4827

64

0.0661

38

0.0694

22

0.1355

6

0.3816

76

2.7666

32

0.9310

04

0.4746

46

0.0647

77

0.0707

83

0.1355

6

0.3897

94

2.7855

91

0.9470

04

0.4560

51

0.0616

74

0.0738

85

0.1355

6

0.4083

88

2.8289

85

0.9550

04

0.4451

31

0.0598

63

0.0756

97

0.1355

6

0.4193

09

2.8544

49

0.9630

04

0.4326

38

0.0578

02

0.0777

58

0.1355

6

0.4318

01

2.8835

56

0.9710

04

0.4179

05

0.0553

84

0.0801

76

0.1355

6

0.4465

34

2.9178

58

0.9831

27 0.3881

0.0505

43

0.0850

17

0.1355

6

0.4763

39

2.9871

5

0.9904

31

0.3607

13

0.0461

57

0.0894

03

0.1355

6

0.5037

27

3.0506

97

1

0.1155

61

0.0110

74

0.1244

86

0.1355

6

0.7488

79

3.6111

67

73

By using data from Table 3.1 and Table 3.2, the graph selectivity versus

conversion can be plotted. From Figure 3.4, it can be observed that at conversion of 0,

the selectivity of acrolein, acetaldehyde, acetonitrile, formaldehyde, acrylonitrile, and

water are 0 as well. Also, when the conversion reach 0.9, the selectivity of

acrylonitrile, acetonitrile and water is expected increase due to the formation high

yield of acrylonitrile, acetonitrile and water. Equation will be fitted for all the

selectivity as range of conversion of 0.01 to 1. Sixth order polynomial regression is

used to form the equation. It can be seen that a high conversion at 0.99 until 1 is the

best since it favours high yield of acrylonitrile.

Figure 3.4 Selectivity vs conversion of Glycerol

Selectivity of Water

S = -151.62x6 + 530.84x5 - 714x4 + 464.06x3 - 149.34x2 + 22.32x + 0.8937

Selectivity of Acrolein

S = -129.39x6 + 406.71x5 - 495.8x4 + 293.74x3 - 86.447x2 + 11.034x + 0.3815

74

Selectivity of Acrylonitrile

S = 28.64x6 - 77.832x5 + 79.859x4 - 38.097x3 + 8.346x2 - 0.3416x + 0.0159

Selectivity of Formaldehyde

S = -15.8x6 + 51.574x5 - 65.227x4 + 40.09x3 - 12.248x2 + 1.6768x + 0.0623

Selectivity of Aldehyde

S = -20.007x6 + 62.985x5 - 76.919x4 + 45.656x3 - 13.455x2 + 1.7063x + 0.06

Selectivity of Acetonitrile

S = 4.2064x6 - 11.412x5 + 11.693x4 - 5.5657x3 + 1.207x2 - 0.0294x + 0.0024

3.2.2 Raw Material and Product

The raw materials involved in the manufacture of acrylonitrile (ACN) is crude

glycerol, ammonia and oxygen while the main product is acrylonitrile and by product

will be acetonitrile and formaldehyde. Since it is two series process, acrolein and

aldehyde act as intermediate products. Sulphuric acid is used in pre-treatment of crude

glycerol and acts as absorbent in quenching tower T-101.

Table 3.3 Physical properties of glycerol

Characteristics Properties

Physical state and appearance

Molecular weight

Liquid

92.05 g/mol

Boiling point

Melting point

Flash point

290 oC

20 oC

193 oC

Density

Viscosity

Critical point

1.26 g/cm3

1.412 Pa.s (25oC)

577 oC @ 7500 kPa

Specific gravity 0.806

75

Vapor pressure 0.025 mm Hg @ 5oC

Vapor density 3.17 (H2O =1)

Solubility Soluble in water

Source: Science Lab 2014

Table 3.4 Physical properties of ammonia


Physical state and appearance Gas, Colorless

Taste Alkaline

Molecular weight 17 g/mol

Boiling point -33.4 oC @ 1atm

Melting point -77.7 oC


Vapor pressure 114.4 @ 21oC

Gas density 0.045 lb/ft3 @ 21oC

Autoignition temperature 651oC



Table 3.5 Physical properties of oxygen


Physical state and appearance Gas, Colorless

Taste Odorless

Molecular weight 32 g/mol

Boiling point -183 oC @ 1atm



Gas density 0.083 lb/ft3 @ 21oC



76

Table 3.6 Physical properties of acrolein


Physical state and appearance Liquid

Odor Pungent, Burnt sweet

Molecular weight 56.06 g/mol

Boiling point 52.5 oC

Melting point -88 oC

Critical temperature 254oC

Specific gravity 0.8389 @ (Water = 1)

Vapor density 1.94 @ (Air = 1)



Table 3.7 Physical properties of acetaldehyde


Physical state and appearance Liquid, colorless

Odor Strong Pungent, fruity


Boiling point 21 oC


Critical temperature 188 oC





Table 3.8 Physical properties of formaldehyde


Physical state and appearance Liquid, clear colorless

Odor Strong Pungent, Suffocating

77


Boiling point 98 oC


Critical temperature 240oC





Table 3.9 Physical properties of acrylonitrile (ACN)


Physical state and appearance

Molecular weight

Liquid

53.06 g/mol

Boiling point

Melting point

Flash point

77.3oC (171.1oF)

-82oC (-115.6oF)

-4.4 oC

Density

Viscosity

Critical temperature

0.7951 g/cm3

0.34 cP (25oC)

262.78oC (505oF)


Vapor pressure 11.1 kPa @ 20oC

Vapor density 1.8 (Air=1)

Solubility - Soluble in diethyl ether, acetone, organic

substances, isopropyl alcohol and benzene

- Very slightly soluble in water


Table 3.10 Physical properties of acetonitrile


Physical state and appearance Liquid, colorless

Odor Strong Aromatic, Ether-like

78


Boiling point 81.6 oC




Solubility Soluble in water, methanol


Table 3.11 Physical properties of suphuric acid


Physical state and

appearanceThick oily liquid

Odor Odourless but choking odour when hot


Boiling point 270 oC


Solubility Miscible in water


3.2.3 Design Constraint

Design constraints of a process should be identified first to ensure that the designed

plant is safe to operate, the environment is protected and also sustainability criteria is

considered. Production of acrylonitrile in the plant is by using crude glycerol as raw

material but the crude glycerol which contains high composition of various impurities

creates an urge to undergo a pre-treatment process and being purified until reach

approximately 94% before proceeding to the reaction stream.

Besides, production of acrylonitrile is a two-step reaction where the first

reaction produces acrolein as an intermediate. The first reaction is carried out in vapor

phase condition, at temperature 300oC at 1.6 bar pressure and WO3/TiO2 as reaction

catalyst inside the reactor. WO3/TiO2 stands for Tungsten (VI) oxide/Titanium dioxide

79

is chosen as a suitable catalyst for this reaction because it has large surface area,

capable to increase the separation efficiencies of electron and hole pairs, high energy

storage capability, extended lifetime and consequently improves the interfacial

transfer yield. . The lifetime of this catalyst is about 2-3 years and can be regenerated.

(Izadifard, M. et al. 2014).

For the second reaction, ammoxidation of acrolein is occurred to produce

acrylonitrile. This reaction is carried out in extremely high temperature about 350 oC at

2.2 bar pressure and in a vapor phase condition with an aid of antimony ferum oxide

(SbFeO) as reaction catalyst. SbFeO catalyst exhibits respectable yield of acrylonitrile

in the ammoxidation of acrolein. It has quite high selectivity towards the desired

product and also decreases the formation of side products such as acetonitrile. The

lifetime of this catalyst is around 1-2 years (Holderich,W. F. & Pfennig, A. 2013).

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