Chapter13 - valvBlending

Petroleum Refining – Chapter 13: Product Blending

1

Chapter 13

Product Blending

Introduction The major refinery products produced by blending are:

- Gasoline

- Jet fuels

- Diesel fuel

- Furnace oils.

- Residual fuels.

- Heating oils

- Lubricating oils

More restrictions on

product specs

Refinery sources of gasoline (blending components)

- Straight-run gasoline (CDU naphtha).

- Coker gasoline

- FCC/TCC gasoline

- Hydrocracker gasoline (hydrocrackate)

- Reforming (reformate)

- Alkylation (alkylate)

- Polymerization (polymerate)

- Isomerization (isomerate)

- ARDS/isomax gasoline

- H-oil gasoline

- Thermal cracker gasoline.

- Aromatic concentrate

- C4+ Gases

- Other

These have different molecular contents and performance

qualities (RON, MON, RVP, API, BP range, etc.) as shown in

Table 13.1.

They must be blended into various grades that meet market

demands.

Copyrights © 2001 – 2014, Dr. Tareq Albahri, Chem. Eng. Dept., Kuwait University

2

TABLE 13.1: Blending Component Values for Gasoline Blending Streams.

No Component RVP (psi) MON RON °API

1. i-C4 71.0 92.0 93.0

2. n-C4 52.0 92.0 93.0

3. i-C5 19.4 90.8 93.2

4. n-C5 14.7 72.4 71.5

5. i-C6 6.4 78.4 79.2

6. LSR gasoline (C5-180°F) 11.1 61.6 66.4 78.6

7. LSR gasoline Isomerized, once-through 13.5 81.1 83.0 80.4

8. HSR gasoline 1.0 58.7 62.3 48.2

9. Lt hydrocrackate 12.9 82.4 82.8 79.0

10. Hydrocrackate, C5-C6 15.5 85.5 89.2 86.4

11. Hydrocrackate, C6-l90 °F 3.9 73.7 75.5 85.0

12. Hydrocrackate, 190-250 °F 1.7 75.6 79.0 55.5

13. Hvy hydrocrackate 1.1 67.3 67.6 49.0

14. Coker gasoline 3.6 60.2 67.2 57.2

15. Lt thermal gasoline. 9.9 73.2 80.3 74.0

16. C6+ lt thermal gasoline. 1.1 68.1 76.8 55.1

17. FCC gasoline, 200-300 °F 1.4 77.1 92.1 49.5

18. FCC C5+ gasoline 4.4 76.8 92.3 57.2

19. Hydrog lt FCC gasoline, C5+ 13.9 80.9 83.2 51.5

20. Hydrog C5-200 °F FCC gasoline 14.1 81.7 91.2 58.1

21. Hydrog 1t FCC gasoline, C6+ 5.0 74.0 86.3 49.3

22. Hydrog C5+ FCC gasoline 13.1 80.7 91.0 54.8

23. Hydrog 300-400 °F FCC gasoline 0.5 81.3 90.2 48.5

24. Reformate, 94 RON 2.8 84.4 94.0 45.8

25. Reformate, 98 RON 2.2 86.5 98.0 43.1

26. Reformate, 100 RON 3.2 88.2 100.0 41.2

27. Aromatic concentrate 1.1 94.0 107.0

28. Alkylate, C3= 5.7 87.3 90.8

29. Alkylate, C4= 4.6 95.9 97.3 70.3

30. Alkylate, C3=, C4= 5.0 93.0 94.5

31. Alkylate, C5= 1.0 88.8 89.7

32. Polymer 8.7 84.0 96.9 59.5

33. C5+ TCC gasoline 4.0 76.6 85.5

34. C6+ TCC gasoline 2.6 75.8 84.3

These values are provided for illustration and cannot be generalized.


3

Blending components must meet all desired

specifications like boiling point, specific gravity, RVP,

research octane number (RON) and motor octane number

(MON) to provide feedback control of additives and

blending streams.

Basic intermediate streams can be blended to produce a

variety of on-spec finished products.

For example, naphtha can be blended into either gasoline

or jet fuel, depending upon the product demand.

The objective of product blending is to allocate the

available blending components in such a way as to meet

product demands and specifications at the least cost and

to produce incremental products which maximize overall

profit.

For example, if a refiner sells about one billion gallons of

gasoline per year (about 65,000 BPCD), a saving of one-

hundredth (1/100) of a cent per gallon results in an

additional profit of $100,000 per year.

Blending for API gravity

API Gravities are not linear and therefore can not be

averaged.

Specific gravity can be volume Averaged.


4

Example 13.1: Blending for API

Calculate the API of a blend from

1,000 bbls oil 30 ºAPI

3,000 bbls oil 40 ºAPI

Solution:

141.5 141.5= = 0.8251 sp.gr.

API + 131.5 30 + 131.5

141.5 141.5= = 0.8762 sp.gr.

API + 131.5 40 + 131.5

Ave. sp. gr. = 0.25(0.8251) + 0.75(0.8762) = 0.8634

API = (141.5/ 0.8634)-131.5 = 32.38 √

If you average the API then the answer is

0.25 x 30 + 0.75 x 40 = 37.5 (which is wrong)

Blending for Initial & Final BP

The initial boiling point of the blend equals the lowest of

the blending stocks and the final boiling point equals the

highest.


5

Example 13.2: Blending for Boiling Point

Calculate the initial and final boiling points of the blend from

the following blending stocks,

LSR gasoline (C5 – 180 ºF)

HSR gasoline (200 – 380 ºF)

FCC gasoline (200 – 300 ºF)

Blend (C5 – 380 ºF)

Blending for Reid Vapor Pressure (RVP)

The theoretical method for blending to the desired RVP

requires the average molecular weight of each of the

streams to be known.

A more convenient way developed by Chevron Research

Company is to use ‘Vapor Pressure Blending Indices’

(VPBI) compiled as a function of the RVP of the

blending streams as shown in Table 13.2.

The RVP of the blend is closely approximated by the

sum of all the products of the volume fraction (Xv) times

the VPBI for each component.

(VPBI)blend = ∑ Xvi (VPBI)i

The desired RVP of a gasoline is obtained by blending n-

butane with (C5 – 380°F) naphtha.

If the volume of the n-butane to be blended for a given

RVP is desired, then


6

Table 13.2: Reid Vapor Pressure Blending Index Numbers for Gasoline and Turbine Fuels.

Vapor

Pressure,

psi

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

0.00

1.00

2.37

3.94

5.65

7.47

9.39

11.4

13.4

15.6

17.8

20.0

22.3

24.7

27.1

29.5

32.0

34.5

37.1

39.7

42.3

45.0

47.6

50.4

53.1

55.9

58.7

61.5

64.4

67.3

0.05

1.12

2.52

4.11

5.83

7.66

9.58

11.6

13.7

15.8

18.0

20.3

22.6

24.9

27.3

29.8

32.2

34.8

37.3

39.9

42.6

45.2

47.9

50.6

53.4

56.2

59.0

61.8

64.7

67.6

0.13

1.25

2.67

4.28

6.01

7.85

9.78

11.8

13.9

16.0

18.2

20.5

22.8

25.2

27.6

30.0

32.5

35.0

37.6

40.2

42.8

45.5

48.2

50.9

53.7

56.5

59.3

62.1I

65.0

67.9

0.22

1.38

2.83

44.4

6.19

8.04

9.98

12.0

14.1

16.2

18.4

20.7

23.0

25.4

27.8

30.2

32.8

35.3

37.8

40.4

43.1

45.8

48.4

51.2

54.0

56.7

59.6

62.4

65.3

68.2

0.31

1.52

2.98

4.61

6.37

8.23

10.2

12.2

14.3

16.4

18.7

20.9

23.3

25.6

28.0

30.5

33.0

35.5

38.1

40.7

43.4

46.0

48.7

51.5

54.2

57.0

59.8

62.7

65.6

68.4

0.42

1.66

3.14

4.78

6.55

8.42

10.4

12.4

14.5

16.7

18.9

21.2

23.5

25.9

28.3

30.8

33.2

35.8

38.4

41.0

43.6

46.3

49.0

51.7

54.5

57.3

60.1

63.0

65.8

68.8

0.52

1.79

3.30

4.95

6.73

8.61

10.6

12.6

14.7

16.9

19.1

21.4

23.7

26.1

28.5

31.0

33.5

36.0

38.6

41.2

43.9

46.6

49.3

52.0

54.8

57.5

60.4

63.3

66.1

69.0

0.64

1.94

3.46

5.13

6.92

8.80

10.8

12.8

14.9

17.1

19.4

21.6

24.0

26.4

28.8

31.2

33.8

36.3

38.9

41.5

44.2

46.8

49.5

52.3

55.1

57.9

60.7

63.5

66.4

69.3

0.75

2.08

3.62

5.30

7.10

9.00

11.0

13.0

15.2

17.3

19.6

21.9

24.2

26.6

29.0

31.5

34.0

36.6

39.1

41.8

44.4

47.1

49.8

52.6

55.3

58.1

61.0

63.8

66.7

69.6

0.87

2.23

3.78

5.48

7.29

9.19

11.2

13.2

15.4

17.6

19.8

22.1

24.4

26.8

29.3

31.8

34.3

36.8

39.4

42.0

44.7

47.4

50.1

52.8

55.6

58.4

61.3

64.1

67.0

69.9

30

40

70.2

101

Example:

Calculate the vapor-pressure of a gasoline blend as follows

(nC4) 51.6

(iC4) 72.2

(C3) 190.0

138

210

705

Component

Volume

Fraction

Vapor

Pressure

psi

Vapor

Pressure

Blending

Index No.

Volume

Fraction

x

VPBI

Equation:

VPBI = VP1.25

n-Butane

Light Straight Run

Heavy Refined

Total

0.050

0.450

0.500

1.000

51.6

6.75

1.00

7.40

138

10.9

1.00

12.3

6.90

4.90

0.50

12.3

From the brochure, “31.O°API Iranian Heavy Crude Oil,” by arrangement with Chevron

Research Company. Copyright © 1971 by Chevron Oil Trading Company.


7

V1 (VPBI)1 + V2 (VPBI)2 + …...……+ V0 (VPBI)0

= (V1 + V2 + … + V0) (VPBI)m

where

V0 = Volume (bbl) of n-butane.

V1 = Volume (bbl) of blending stock 1.

1, 2, 3 = blending stocks 1, 2, 3, etc.

(VPBI)m = VPBI of the mixture

RVPm1.25 = [V1(RVP1)1.25 + V2(RVP2)1.25 + ….]/ total volume

Blending for Octane Number

Octane numbers are blended on a volumetric basis.

True octane numbers do not blend linearly. Therefore,

blending octane numbers are used.

Those are numbers which, when added on a volumetric

average basis, will give the true octane of the blend.

Blending octane numbers are based upon experience.

True octane is defined as the octane number obtained

using a CFR test engine.

The formula used for calculations is:


8

Vt (ON)t = ∑ Vi (ON)i

where,

Vt = Total gasoline blended (bbl).

Vi = Volume of component i (bbl).

(ON)t = Desired octane of blend.

(ON)i = Blending octane number of component i.

If n-butane alone is not sufficient to increase the Pool

octane number of the gasoline, different ways are used to

improve the octane number of the gasoline. These are:

1. Increase severity of reforming to produce a 98.8 or

100 RON (clear) reformate.

Note: This is not attractive because the aromatics

content of the gasoline would increase and the

volume would decrease.

2. Use an octane blending agent, such as MTBE or

ETBE (Table 13.3) to improve the pool octane.

Table 13.3: Blending values of octane improvers Compound Formula MW API Tb (ºF) RVP (psi) Flash

point (ºF)

RON MON

Methanol

Ethanol

TBA

MTBE

ETBE

TAME

TEL

CH4O

C2H6O

C4H10O

C5H12O

C6H14O

C6H14O

C8H20Pb

32

46.1

74.1

88.1

102.2

102.2

323.4

46.2

46.1

47.4

58.0

56.7

53.7

3.143

148.5

173

180.4

131.4

159.8

185

239

40

11

6

9

4

1.5

0

53.6

53.6

39.2

-18.4

-2.2

12.2

199.4

135

132

106

118

118

111

10,000

105

106

89

101

102

98

13,000


9

Example 13.3 for RVP and Octane Number:

From the following stocks

1,250 bbls HSR gasoline

,750 bbls LSR gasoline

,620 bbls C5+ FCC gasoline

a. Calculate the amount of n-butane required to produce a

gasoline with and RVP of 9 psi.

b. Calculate the RON and MON for the blend?

c. Calculate the posted octane number (PON) if 10 V%

MTBE is added (keeping RVP at 9 psi).

Solution

RVP values are obtained from Table 13.1

VPBI values are obtained from Table 13.2

COMPONENT # BPD RVP

Table 13.1

VPBI

Table 13.2

BPD x VPBI

n-butane 2 W 52 139.64 139.64W

HSR gasoline 8 1250 1.0 1.0 1250.00

LSR gasoline 6 750 11.1 20.3 15225.00

C5+ FCC gasoline 18 620 4.4 6.37 3949.40

Total for blend 2620 + W 139.64W + 20424.4

∑ (BPD) ∑ (BPD.VPBI)

At 9.0 RVP, from Table 13.2, (VPBI)m = 15.6


10

(VPBI)m x ( )BPD BPDxVPBI

15.6 (2620 + W) = 20424.4 + 139.64 W

40872 + 15.6 W = 20424.4 + 139.64W

124.04 W = 20447.6

W = 04.124

6.23454

W = 165 BPD of n-butane

b.

Component # BPD Vol.

Frac. MON

Table 13.1

RON

Table 13.1

MON x

Vol. frac.

RON x

Vol. frac.

n-butane 2 165 0.0592 92.0 93.0 4.85 5.51

HSR gasoline 8 1250 0.4488 58.7 62.3 26.34 27.96

LSR gasoline 6 750 0.2693 61.6 66.4 16.59 17.88

C5+ FCC

gasoline

18 620 0.2226 76.8 92.3 17.10 20.55

Total for blend 2785 64.9 71.9

MON of the blend = ∑MON x vol. frac. = 64.9

RON of the blend = ∑RON x vol. frac. = 71.9

10 % is equal to 0.1(2785) = 278.5

Octane number values are obtained form Table 13.3

Component BPD Vol.

Frac.

MON RON MON x Vol.

frac.

RON x

Vol. frac.

n-butane 165 0.054 92.0 93.0 4.97 5.022

HSR gasoline 1250 0.408 58.7 62.3 23.95 25.42

LSR gasoline 750 0.245 61.6 66.4 15.1 16.27

C5 FCC gasoline 620 0.202 76.8 92.3 15.51 18.64

MTBE 278.5 .091 101 118 9.19 10.74

Total 3063.5 68.72 76.1

PON of the blend = (vol. frac. x RON) (vol.frac. x MON)

2

=

76.1 68.72

2

= 72.4


11

BLENDING FOR OTHER PROPERTIES

Several methods exist for estimating the physical

properties of a blend from those of the blending stocks.

One of the most convenient methods of estimating

properties, that do not blend linearly, is to substitute for

the value of the inspection to be blended another value

which has the property of blending approximately linear.

Such values are called blending factor or index.

The Chevron Research Company has compiled factors or

index numbers for,

Viscosities, Table 13.4

Flash points, Table 13.5

Aniline points, Table 13.6

Pour point, Table 13.7

Blending for Viscosity

Viscosity blending is more complicated than the others.

It is not an additive property and it is necessary to use

special techniques to estimate the viscosity of a blend

from the viscosities of its blending stocks.

The method most commonly accepted is the use of

special charts developed by and obtainable from ASTM.

The viscosity factor of the blend can be calculated using

the equation:

(VF) blend = ∑ Xvi (VF)i


12

where,

Xvi = Volume fraction.

(VF)i = Viscosity factor for component i (Table 13.4).

(VF)blend = Viscosity factor for the blend.

Blending of kinematic viscosities (centistokes, cSt) may

be done at any temperature, but the viscosities of all

components of the blend must be at the same

temperature.

Blending of Saybolt universal viscosities also may be

done at any temperature and interchangeably with

kinematic viscosities at the same temperature.

Table 13.4 may be used to convert viscosities expressed

in centistokes (cSt) to Saybolt Universal Seconds (SUS)

and vice versa.

Viscosity factors also are given in Table 13.4 for

viscosities expressed in Saybolt Furol Seconds (SFS).

Saybolt Furol viscosities are blended only at 122°F.

If SFS viscosities are at any other temperature, they must

be converted to centistokes or SUS before blending.

Viscosity factors for SFS at 122 °F may be used

interchangeably with viscosity factors for SUS at 130 °F

and with centistokes at 130 °F.

Table 13.4 may be used also to convert viscosities in SFS

at 122 °F to either kinematic or Saybolt Universal

viscosities at 130 °F.

Other viscosity units include

- Redwood sec


13

- Redwood Admiralty Seconds

- Redwood No.1 Seconds

The viscosity of a blend can also be estimated by API

Procedure 11A4.3 in the API Technical Data Book -

Petroleum Refining.

Table 13.4 maybe digitized and the following equations

are obtained,

X1 = log (visc.1)

11 2

1 1

0.17011008+0.5237753 X

1+0.51237772 X 0.012329287 XVF

1 1 2 2

1 2

V VF V VF ...

V V ...blendVF

blend

2

blend blend

0.31495388+1.796746 (VF )log( . )

1 1.2634231 (VF ) 0.44952981 (VF )blendvisc

Example: using equations above

visc.i VFi Vi vol frac x factor

500 0.691 0.3333 0.230

300 0.669 0.3333 0.223

200 0.651 0.3334 0.217

Total 0.670

Log (viscblend) = 2.503

Visc = 318 cSt


14

Blending for Flash Point

The flash point index of a blend is given by

(FPBI) blend = ∑ Xvi (FPBI)i

where

(FPBI) blend = Aniline point blending index of the blend.

(FPBI)i = Aniline point blending index of component

i from Table 13.5.

Xvi = The volume fraction.

Blending for Aniline Point

The aniline point index of a blend is given by

(APBI) blend = ∑ Xvi (APBI)i

where

(APBI) blend = Aniline point blending index of the blend.

(APBI)i = Aniline point blending index of component

i from Table 13.6.


Blending for Pour Point


15

The pour point index of a blend is given by

(PP) blend = ∑ Xvi (PPBI)i

where

(PP) blend = Pour point blending index of the blend.

(PPBI)i = Pour point blending index of component i

from Table 13.7.


Example 13.4:

Calculate the viscosity, flash point, aniline point, and pour point of the blend from the

following blending stocks.

Stock bbls ASTM 50%

temp (ºF)

Viscosity Flash

point (ºF)

Aniline

point (ºF)

Pour

point (ºF)

A

B

C

5,000

3,000

2,000

575

425

500

430 SFS at 120 ºF

82.5 SUS at 130 ºF

2.15 cSt at 130 ºF

100

90

130

70

160

40 (mixed)

10

50

65

Solution:

a. Viscosity

Stock vol. frac. of

blend

Viscosity Factor

(T13.4)

vol. frac. x

Factor

A

B

C

0.5

0.3

0.2

430 SFS at 120 ºF

82.5 SUS at 130 ºF

2.15 cSt at 130 ºF

0.700

0.500

0.300

0.350

0.150

0.060

Total 1 0.560

Table 13.4 gives the following viscosities for a blend with a factor of 0.56

39.5 cSt at 130 ºF

183 SUS at 130 ºF

25.7 SFS at 122 ºF


16

b. Flash point

Stock vol. frac. of

blend

Flash point (ºF) Blending Index

(T13.5)

vol. frac. x

index

A

B

C

0.5

0.3

0.2

100

90

130

753

1,170

224

376.5

351

44.8

Total 1 772

Table 13.5 gives a flash point for the blend of 99.5 ºF for a blending index of 772.

c. Aniline Point

Stock vol. frac. of

blend

Aniline point (ºF) Blending Index

(T13.6)

vol. frac. x

index

A

B

C

0.5

0.3

0.2

70

160

40 (mixed)

347

855

-425

173.5

256.5

-85

Total 1 345

Table 13.6 gives for a blending index of 345 an aniline point for the blend of 69.5 ºF or a

mixed aniline point of 115 ºF.

d. Pour Point

Stock vol. frac. of

blend

ASTM 50%

temp (ºF)

Pour Point

(ºF)

Blending Index

(T13.7)

vol. frac. x

index

A

B

C

0.5

0.3

0.2

575

425

500

10

50

65

8

61

98

4

18.3

19.6

Total 1 41.9

The pour point of the blend is 41.9 ºF or 42 ºF.


17

TABLE 13.4: Viscosity Blending Index Numbers Factors for Volume Blending of Viscosities at Constant Temperatures

Corresponding to values of Kinematic Viscosity, Centistokes (cSt).

cSt

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.5

0.6

0.7

0.8

0.9

0.000

0.056

0.097

0.128

0.154

0.006

0.061

0.100

0.131

0.156

0.013

0.065

0.104

0.134

0.159

0.019

0.069

0.107

0.137

0.161

0.025

0.074

0.110

0.139

0.163

0.030

0.078

0.114

0.142

0.165

0.036

0.082

0.117

0.144

0.167

0.041

0.086

0.120

0.147

0.169

0.046

0.089

0.123

0.149

0.172

0.051

0.093

0.126

0.152

0.174

cSt

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

2

3

4

5

6

7

8

9

0.176

0.290

0.342

0.375

0.398

0.416

0.431

0.443

0.453

0.194

0.297

0.346

0.378

0.400

0.418

0.432

0.444

0.454

0.210

0.303

0.350

0.380

0.402

0.419

0.433

0.445

0.455

0.224

0.309

0.353

0.383

0.404

0.421

0.434

0.446

0.456

0.236

0.314

0.357

0.385

0.406

0.422

0.436

0.447

0.456

0.247

0.320

0.360

0.387

0.408

0.423

0.437

0.448

0.457

0.257

0.325

0.363

0.390

0.410

0.425

0.438

0.449

0.458

0.266

0.329

0.366

0.392

0.411

0.426

0.439

0.450

0.459

0.275

0.334

0.369

0.394

0.413

0.428

0.440

0.451

0.460

0.283

0.338

0.372

0.396

0.414

0.429

0.442

0.452

0.461

cSt

0

1

2

3

4

5

6

7

8

9

10

20

30

40

50

60

70

80

90

0.462

0.515

0.543

0.561

0.575

0.585

0.594

0.601

0.608

0.470

0.519

0.545

0.563

0.576

0.586

0.595

0.602

0.608

0.477

0.522

0.547

0.564

0.577

0.587

0.596

0.603

0.609

0.483

0.525

0.549

0.566

0.578

0.588

0.596

0.603

0.610

0.489

0.528

0.551

0.567

0.579

0.589

0.597

0.604

0.610

0.494

0.531

0.553

0.568

0.580

0.590

0.598

0.605

0.611

0.499

0.533

0.555

0.570

0.581

0.591

0.599

0.605

0.611

0.503

0.536

0.557

0.571

0.582

0.592

0.599

0.606

0.612

0.508

0.538

0.558

0.572

0.583

0.592

0.600

0.607

0.612

0.511

0.541

0.559

0.573

0.584

0.593

0.601

0.607

0.613


18

cSt

0

10

20

30

40

50

60

70

80

90

100

200

300

400

500

600

700

800

900

0.613

0.648

0.667

0.680

0.689

0.697

0.703

0.708

0.713

0.618

0.651

0.669

0.681

0.690

0.698

0.704

0.709

0.714

0.623

0.653

0.670

0.682

0.691

0.698

0.704

0.709

0.714

0.627

0.655

0.671

0.683

0.692

0.699

0.705

0.710

0.715

0.631

0.657

0.673

0.684

0.692

0.700

0.705

0.710

0.715

0.634

0.659

0.674

0.685

0.693

0.700

0.706

0.711

0.715

0.637

0.661

0.675

0.686

0.694

0.701

0.706

0.711

0.716

0.640

0.662

0.676

0.687

0.695

0.701

0.707

0.712

0.716

0.643

0.664

0.678

0.688

0.696

0.702

0.707

0.712

0.716

0.646

0.666

0.679

0.688

0.696

0.702

0.708

0.713

0.717

cSt

0

100

200

300

400

500

600

700

800

900

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0.717

0.743

0.757

0.767

0.775

0.780

0.785

0.790

0.793

0.721

0.745

0.758

0.768

0.775

0.781

0.786

0.790

0.794

0.724

0.747

0.759

0.769

0.776

0.781

0.786

0.790

0.794

0.727

0.748

0.761

0.770

0.777

0.782

0.787

0.791

0.794

0.730

0.750

0.762

0.770

0.778

0.782

0.787

0.791

0.795

0.733

0.751

0.763

0.771

0.778

0.783

0.787

0.791

0.795

0.735

0.752

0.764

0.772

0.778

0.783

0.788

0.792

0.795

0.737

0.754

0.765

0.772

0.779

0.784

0.788

0.792

0.796

0.739

0.755

0.765

0.773

0.779

0.784

0.789

0.792

0.796

0.741

0.756

0.766

0.774

0.780

0.785

0.790

0.793

0.796

cSt

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

0.796

0.817

0.828

0.836

0.842

0.847

0.851

0.854

0.858

0.799

0.818

0.829

0.837

0.843

0.848

0.802

0.820

0.830

0.838

0.843

0.848

0.804

0.821

0.831

0.838

0.844

0.848

0.806

0.822

0.832

0.839

0.844

0.849

0.808

0.823

0.833

0.839

0.845

0.849

0.810

0.824

0.833

0.840

0.845

0.850

0.812

0.825

0.834

0.841

0.846

0.850

0.814

0.826

0.835

0.841

0.846

0.850

0.815

0.827

0.836

0.842

0.847

0.851


19

cSt

cSt cSt

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

0.860

0.877

0.887

0.894

0.899

0.903

0.906

0.909

0.912

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

0.914

0.928

0.937

0.942

0.947

0.950

0.953

0.956

0.958

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

80,000,000

90,000,000

0.960

0.973

0.980

0.985

0.989

0.992

0.995

0.997

0.999

Factors for Volume Blending of Viscosities at Constant Temperatures

Corresponding to values of Saybolt Universal Seconds (SUS).

SUS

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

32

33

34

35

36

37

38

39

0.275

0.296

0.314

0.328

0.342

0.353

0.363

0.373

0.278

0.298

0.315

0.330

0.343

0.354

0.364

0.373

0.280

0.300

0.317

0.331

0.344

0.355

0.365

0.374

0.282

0.302

0.318

0.333

0.345

0.356

0.366

0.375

0.284

0.303

0.320

0.334

0.346

0.357

0.367

0.376

0.286

0.305

0.321

0.335

0.347

0.358

0.368

0.377

0.288

0.307

0.323

0.337

0.349

0.359

0.369

0.378

0.290

0.309

0.324

0.338

0.350

0.360

0.370

0.378

0.292

0.310

0.326

0.339

0.351

0.362

0.371

0.379

0.294

0.312

0.327

0.340

0.352

0.363

0.372

0.380

SUS

0

1

2

3

4

5

6

7

8

9

40

50

60

70

80

90

0.381

0.435

0.464

0.483

0.497

0.508

0.388

0.439

0.466

0.485

0.498

0.509

0.395

0.442

0.469

0.486

0.499

0.510

0.402

0.445

0.471

0.488

0.501

0.511

0.408

0.449

0.473

0.489

0.502

0.512

0.413

0.451

0.475

0.491

0.503

0.513

0.418

0.454

0.476

0.492

0.504

0.513

0.423

0.457

0.478

0.493

0.505

0.514

0.428

0.459

0.480

0.495

0.506

0.515

0.431

0.462

0.482

0.496

0.507

0.516


20

SUS

0

10

20

30

40

50

60

70

80

90

100

200

300

400

500

600

700

800

900

0.517

0.565

0.589

0.605

0.617

0.627

0.635

0.641

0.647

0.524

0.568

0.591

0.607

0.618

0.628

0.635

0.642

0.647

0.531

0.571

0.593

0.608

0.619

0.628

0.636

0.642

0.648

0.537

0.574

0.595

0.609

0.620

0.629

0.637

0.643

0.648

0.542

0.576

0.596

0.611

0.621

0.630

0.637

0.643

0.649

0.547

0.579

0.598

0.612

0.622

0.631

0.638

0.644

0.649

0.551

0.581

0.600

0.613

0.623

0.632

0.639

0.645

0.650

0.555

0.583

0.601

0.614

0.624

0.632

0.639

0.645

0.650

0.559

0.585

0.603

0.615

0.625

0.633

0.640

0.646

0.651

0.562

0.587

0.604

0.616

0.626

0.634

0.640

0.646

0.651

SUS

0

100

200

300

400

500

600

700

800

900

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0.652

0.683

0.700

0.711

0.720

0.727

0.733

0.738

0.742

0.656

0.685

0.701

0.712

0.721

0.728

0.733

0.738

0.742

0.660

0.687

0.703

0.713

0.722

0.728

0.734

0.739

0.743

0.664

0.689

0.704

0.714

0.722

0.729

0.734

0.739

0.743

0.667

0.691

0.705

0.715

0.723

0.729

0.735

0.740

0.744

0.670

0.692

0.706

0.716

0.724

0.730

0.735

0.740

0.744

0.673

0.694

0.707

0.717

0.725

0.731

0.736

0.740

0.744

0.676

0.696

0.708

0.718

0.725

0.731

0.736

0.741

0.745

0.678

0.697

0.709

0.719

0.726

0.732

0.737

0.741

0.745

0.681

0.699

0.710

0.719

0.726

0.732

0.737

0.742

0.745

SUS

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10,000

20,000

30,000

40,000

50,000

60,000

0.746

0.770

0.783

0.792

0.799

0.804

0.749

0.771

0.784

0.793

0.799

0.805

0.752

0.773

0.785

0.793

0.800

0.805

0.755

0.774

0.786

0.794

0.800

0.806

0.758

0.776

0.787

0.795

0.801

0.806

0.760

0.777

0.788

0.795

0.802

0.807

0.762

0.778

0.789

0.796

0.802

0.807

0.764

0.779

0.790

0.797

0.803

0.807

0.766

0.781

0.790

0.797

0.803

0.808

0.768

0.782

0.791

0.798

0.804

0.808


21

SUS

SUS

SUS

SUS

70,000

80,000

90,000

0.809

0.813

0.816

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

0.819

0.838

0.849

0.856

0.862

0.867

0.870

0.874

0.877

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

0.879

0.895

0.904

0.911

0.915

0.919

0.923

0.925

0.928

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

80,000,000

90,000,000

0.930

0.944

0.952

0.957

0.961

0.965

0.968

0.970

0.972

Factors for Volume Blending of Viscosities at 130 °F Corresponding to values

of Saybolt Furol Seconds (SFS) at 122 °F.

SFS

at

122

°F

0

1

2

3

4

5

6

7

8

9

20

30

40

50

60

70

80

90

0.570

0.588

0.601

0.611

0.619

0.626

0.632

0.572

0.590

0.602

0.612

0.620

0.627

0.633

0.574

0.591

0.604

0.613

0.621

0.627

0.633

0.576

0.593

0.605

0.614

0.622

0.628

0.634

0.578

0.594

0.606

0.615

0.622

0.629

0.634

0.558

0.580

0.595

0.607

0.616

0.623

0.629

0.635

0.561

0.582

0.597

0.608

0.616

0.624

0.630

0.635

0.563

0.584

0.598

0.609

0.617

0.624

0.630

0.636

0.566

0.585

0.599

0.610

0.618

0.625

0.631

0.636

0.568

0.587

0.600

0.610

0.619

0.626

0.632

0.637


22

SFS

at

122

°F

0

10

20

30

40

50

60

70

80

90

100

200

300

400

500

600

700

800

900

0.637

0.669

0.686

0.697

0.706

0.713

0.719

0.724

0.728

0.642

0.671

0.687

0.698

0.707

0.713

0.719

0.724

0.728

0.646

0.673

0.688

0.699

0.707

0.714

0.720

0.724

0.729

0.649

0.675

0.689

0.700

0.708

0.715

0.720

0.725

0.729

0.653

0.676

0.691

0.701

0.709

0.715

0.721

0.725

0.729

0.656

0.678

0.692

0.702

0.710

0.716

0.721

0.726

0.730

0.659

0.680

0.693

0.703

0.710

0.716

0.722

0.726

0.730

0.661

0.681

0.694

0.703

0.711

0.717

0.722

0.727

0.730

0.664

0.683

0.695

0.704

0.712

0.718

0.723

0.727

0.731

0.666

0.684

0.696

0.705

0.712

0.718

0.723

0.727

0.731

SFS

at

122

°F

0

100

200

300

400

500

600

700

800

900

1000

2000

3000

0.732

0.755

0.769

0.735

0.757

0.770

0.738

0.759

0.771

0.741

0.760

0.772

0.743

0.761

0.773

0.746

0.763

0.773

0.748

0.764

0.775

0.750

0.764

0.775

0.752

0.766

0.776

0.754

0.767

0.777

4000

5000

6000

7000

8000

9000

0.778

0.784

0.790

0.795

0.798

0.802

Notes:

Values from this table are for 130 ºF, although the Saybolt Furol

seconds are at 122 ºF. This table alone must not be used for any

other temperatures. Values from this table may be used

interchangeably with values for kinematic and Saybolt Universal

viscosities if the latter are for 130 ºF.

For SFS at 210 ºF, assume SUS – 10 x SFS and use the Saybolt

Universal table.


23

Table 13.5: Flash Point Blending Index Numbers. Flash

Point,

°F

0

1

2

3

4

5

6

7

8

9

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

168,000

86,600

46,000

25,200

14,200

8,240

4,890

2,970

1,840

1,170

753

495

331

224

154

108

76.3

54.7

39.7

29.1

21.6

16.1

12.2

9.31

7.16

5.56

4.35

3.43

2.72

2.17

157,000

81,200

43,300

23,800

13,500

7,810

4,650

2,830

1,760

1,120

722

475

318

216

149

104

73.8

52.9

38.4

28.2

20.9

15.7

11.9

9.07

6.98

5.42

4.24

3.35

2.66

2.12

147,000

76,100

40,700

22,400

12,700

7,410

4,420

2,700

1,680

1,070

692

456

305

305

144

101

71.4

51.3

37.3

27.4

20.3

15.2

11.6

8.83

6.80

5.29

4.14

3.27

2.60

2.08

137,000

71,400

38,300

21,200

12,000

7,030

4,200

2,570

1,600

1,020

662

438

294

200

138

97.1

69.0

49.6

36.1

26.6

19.7

14.8

11.2

8.60

6.63

5.16

4.04

3.19

2.54

2.03

128,000

67,000

36,100

20,000

11,400

6,670

4,000

2,450

1,530

978

635

420

283

193

134

93.8

66.7

48.0

35.0

25.8

19.2

14.4

10.9

8.37

6.47

5.03

3.95

3.12

2.48

1.99

120,000

62,900

34,000

18,900

10,800

6,330

3,800

2,330

1,460

935

609

404

272

186

129

90.6

64.5

46.5

33.9

25.0

18.6

14.0

10.6

8.16

6.30

4.91

3.86

3.05

2.43

1.95

112,000

59,000

32,000

17,800

10,200

6,010

3,620

2,230

1,400

896

584

388

261

179

124

87.5

62.4

45.1

32.9

24.3

18.1

13.6

10.4

7.95

6.15

4.79

3.76

2.98

2.37

1.90

105,000

55,400

30,100

16,800

9,680

5,700

3,441

2,120

1,340

857

560

372

252

172

120

84.6

60.4

43.6

31.9

23.6

17.6

13.3

10.1

7.74

5.99

4.68

3.68

2.91

2.32

1.86

98,600

52,100

28,400

15,900

9,170

5,420

3,280

2,020

1,280

821

537

358

242

166

116

81.7

58.4

42.3

30.9

22.9

17.1

12.9

9.82

7.55

5.84

4.56

3.59

2.85

2.27

1.82

92,400

49,000

26,800

15,000

8,690

5,150

3,120

1,930

1,220

786

515

344

233

160

112

79.0

56.5

40.9

30.0

22.2

16.6

12.5

9.56

7.85

5.70

4.45

3.51

2.78

2.22

1.79

Flash

Point,

°F

0

10

20

30

40

50

60

70

80

90

300

400

500

1.75

0.269

0.063

1.41

0.229

0.056

1.15

0.196

0.049

0.943

0.168

0.044

0.777

0.145

0.039

0.643

0.125

0.035

0.535

0.108

0.031

0.448

0.094

0.028

0.376

0.082

0.025

0.317

0.072

0.022

May be used to blend flash temperature, determined in any apparatus but, preferably, not to

blend closed cup with open cup determinations.


24

Table 13.6: Aniline Point Blending Index Numbers. Aniline Point, °F 0 -1 -2 -3 -4 -5 -6 -7 -8 -9

-10

0

20.0

49.1

17.4

46.0

14.9

42.8

12.6

39.8

10.3

36.8

8.10

33.8

6.06

30.9

4.17

28.1

2.46

25.3

1.00

22.6

Aniline Point, °F 0 1 2 3 4 5 6 7 8 9

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

49.1

83.2

121

162

205

250

298

347

398

451

505

560

617

674

733

794

855

917

980

1,044

1,110

1,176

1,242

1,310

1,379

52.4

86.8

125

166

209

255

303

352

403

456

510

566

622

680

739

800

861

923

986

1,050

1,116

1,182

1,249

1,317

1,386

55.6

90.5

129

170

214

260

308

357

408

461

516

571

628

686

745

806

867

930

993

1,057

1,122

1,189

1,256

1,324

1,392

58.9

94.2

133

174

218

264

312

362

414

467

521

577

634

692

751

812

873

936

999

1,064

1,129

1,196

1,262

1,331

1,400

62.3

97.9

137

179

223

269

317

367

419

472

527

582

640

698

757

818

880

942

1,006

1,070

1,136

1,202

1,269

1,337

1,406

65.7

102

141

183

227

274

322

372

424

477

532

588

645

704

763

824

886

948

1,012

1,077

1,142

1,209

1,276

1,344

1,413

69.1

105

145

187

232

279

327

377

429

483

538

594

651

710

769

830

892

955

1,019

1,083

1,149

1,216

1,283

1,351

1,420

72.6

109

149

192

237

283

332

382

435

488

543

599

657

716

775

836

898

961

1,025

1,090

1,156

1,222

1,290

1,358

1,427

76.1

113

153

196

241

288

337

388

440

494

549

605

663

722

781

842

904

967

1,031

1,096

1,162

1,229

1,330

1,365

1,434

79.6

117

157

200

246

293

342

393

445

491

554

611

669

727

788

849

911

974

1,038

1,103

1,169

1,236

1,337

1,372

1,441

Mixed Aniline

Point, °F

0

1

2

3

4

5

6

7

8

9

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

-736

-668

-593

-511

-425

-334

-239

-140

-38.3

66.8

175

285

399

514

632

-730

-660

-584

-503

-416

-324

-229

-130

-27.9

77.4

186

297

410

526

644

-723

-653

-577

-494

-407

-315

-219

-120

-17.5

88.1

197

308

422

538

656

-716

-646

-569

-486

-398

-306

-210

-110

-7.06

98.8

208

319

433

550

668

-709

-639

-561

-477

-389

-296

-200

-100

3.39

110

219

330

445

561

680

-703

-631

-552

-468

-380

-287

-190

-89.6

13.9

120

230

342

456

573

692

-696

-623

-544

-460

-371

-277

-180

-79.4

24.4

131

241

353

468

585

704

-689

-616

-536

-451

-361

-267

-170

-69.2

35.0

142

252

364

479

597

716

-682

-608

-528

-442

-352

-258

-160

-58.9

45.5

153

263

376

491

609

728

-675

-600

-519

-433

-343

-248

-150

-48.6

56.1

164

274

387

503

620

741


25

Table 13.7: Pour Point Blending Indices for Distillate Stocks AST

M

50%

Temp

300

350

375

400

425

450

475

500

525

550

575

600

625

650

675

700

Pour

Point

70

65

60

55

50

45

40

35

30

25

20

15

10

5

0

-5

-10

-15

-20

-25

-30

-35

-40

-45

-50

-55

-60

-65

-70

133

114

99

88

72

60

52

44

37

32

27

23

20

17

14

12

10

8.8

7.5

6.4

5.5

4.6

4.0

3.3

2.8

2.5

2.1

1.8

1.5

131

111

94

79

68

56

48

41

34

29

24

20

17

15

12

10

8.8

7.4

6.3

5.3

4.5

3.7

3.2

2.7

2.3

1.9

1.6

1.4

1.1

129

109

92

77

66

54

46

39

32

27

23

19

16

14

11

9.5

8.0

6.8

5.7

4.7

4.0

3.3

2.8

2.4

2.0

1.7

1.4

1.2

0.99

128

107

90

75

63

52

44

37

31

26

21

18

15

13

10

8.7

7.3

6.1

5.1

4.2

3.6

2.9

2.5

2.1

1.7

1.4

1.2

1.0

0.84

127

105

87

73

61

50

42

35

29

24

20

17

14

12

9.6

8.0

6.6

5.5

4.6

3.7

3.2

2.6

2.2

1.8

1.5

1.2

1.0

0.85

0.71

125

103

85

71

59

48

40

33

27

23

19

16

13

11

8.7

7.2

5.9

4.9

4.1

3.3

2.8

2.3

1.9

1.5

1.3

1.1

0.87

0.72

0.60

123

101

82

68

56

46

38

32

26

21

17

14

12

9.7

7.9

6.5

5.3

4.4

3.6

2.9

2.4

2.0

1.6

1.3

1.1

0.90

0.74

0.60

0.50

120

98

80

66

54

44

36

30

24

20

16

13

11

8.8

7.1

5.8

4.7

3.9

3.2

2.5

2.1

1.7

1.4

1.1

0.93

0.77

0.62

0.50

0.42

118

96

77

63

52

42

34

28

23

18

15

12

9.8

7.9

6.3

5.1

4.1

3.4

2.8

2.2

1.8

1.4

1.2

0.98

0.78

0.65

0.52

0.41

0.36

115

94

74

61

49

40

32

26

21

17

14

11

8.8

7.1

5.6

4.5

3.6

3.0

2.4

1.9

1.5

1.2

1.0

0.82

0.66

0.55

0.43

0.34

0.30

113

91

72

58

47

38

30

24

19

15

12

10

8.0

6.3

5.0

3.9

3.2

2.6

2.1

1.7

1.3

1.0

0.86

0.68

0.56

0.46

0.36

0.28

0.25

110

88

69

56

44

35

28

23

18

14

11

9.0

7.1

5.6

4.4

3.4

2.8

2.2

1.8

1.4

1.1

0.90

0.73

0.58

0.47

0.37

0.30

0.23

0.20

108

85

67

53

42

33

26

21

16

13

10

8.1

6.3

5.0

3.8

3.0

2.5

1.9

1.5

1.2

0.96

0.75

0.62

0.48

0.38

0.30

0.24

0.18

0.15

105

82

64

50

39

31

24

19

15

12

9.1

7.2

5.6

4.4

3.4

2.7

2.2

1.7

1.3

1.0

0.80

0.62

0.51

0.38

0.31

0.24

0.19

0.14

0.11

103

79

62

48

37

29

22

18

14

11

8.3

6.4

5.0

3.8

3.0

2.4

1.9

1.4

1.1

0.90

0.67

0.51

0.41

0.31

0.25

0.19

0.14

0.10

0.08

100

76

60

46

35

27

21

16

13

10

7.5

5.8

4.5

3.5

2.7

2.1

1.6

1.2

0.94

0.72

0.56

0.43

0.33

0.25

0.20

0.15

0.10

0.07

0.05

From Gary & Handwerk

Online Blending

Because of limited storage space, many refineries today

(MAB refinery) use computer-controlled in-line blending

for blending gasoline and other products.


26

Inventories of blending stocks, together with cost and

physical property data are maintained in the computer.

When a certain volume of a given quality product is

specified, the computer uses linear programming models

to optimize the blending operations (select the optimum

volume of blending components) to produce the required

product at the lowest cost.

To ensure that the blended streams meet the desired

specifications, stream analyzers, such as boiling point,

specific gravity, RVP, and research and motor octane are

installed to provide feedback control of blending streams

and additives (if necessary).

Blending components to meet all critical specifications

most economically is a trial-and-error procedure which is

easily handled by a computer.

The large number of variables leads to a number of

equivalent solutions that give the approximate equivalent

total overall cost or profit.

Optimization programs (like PIMS for example) permit

the computer to provide the optimum blend to minimize

cost and maximize profit.

Both linear and nonlinear programming techniques are

used.

Nonlinear programming is preferred if sufficient data are

available to define the equations because components

blend non-linearly and values are functions of the

quantities of the components and their properties (specs).


27

Problems

1. Using values from Table 12.1, calculate the number of barrels of n-butane that have to

be added to a mixture of 1250 barrels of HSR gasoline, 750 barrels of LSR gasoline, and 620 barrels of C5 FCC gasoline to produce a 9 psi Reid vapor pressure. What are the research and motor octane numbers of the blend?

2. For the blend of components in problem 1, what would be the posted octane number of

the 9.0 psi RVP gasoline if 10 vol% MTBE was added to the gasoline mixture?

3. Calculate the amount of n-butane needed to produce a 12.5 psi RVP for a mixture of

2730 barrels of LSR gasoline, 2490 barrels of 94 RON reformate, 6100 barrels of heavy

hydrocrackate, and 3600 barrels of C5 + FCC gasoline. How much ETBE must be added

to produce a 90 RON product? Calculate the RVP of the final blend.

4. What is the flash point of a mixture of 2500 barrels of oil with a flashpoint of 120°F,

3750 barrels with a flashpoint of 35°F, and 5000 barrels with a 150°F flashpoint? 5. Calculate the pour point of the following mixture:

Component

Barrels ASTM

50%

temp., °F

Pour point,

°F

A 5,200 575 10 B 3,000 425 50 C 6,500 500 65 D 3,250 550 45

6. What is the viscosity of a blend of 2000 barrels of oil with a viscosity of 75.5 cSt at 130°F,

3000 barrels with 225 cSt at 130°F, and 5000 barrels with 6500 cSt at 130°F?

7. Calculate the octane numbers of the final blend and amount of n-butane needed for

producing a 9.5 psi RVP gasoline from 5100 BPSD of LSR gasoline, 3000 BPSD light

hydrocrackate, 4250 BPSD alkylate, 10,280 BPSD heavy hydrocrackate, 14,500 BPSD

FCC C5+ gasoline, 14,200 BPSD of 96 RON reformate, and 2500 BPSD of polymer

gasoline.

8. Recommend the best method for increasing the clear posted octane number of the pool

gasoline in problem 7 by 3 numbers. Estimate the cost involved. Assume any necessary

processing units are available and have the necessary capacity.

9. Calculate the number of barrels of n-butane that have to be added to a mixture of 1000

barrels of light thermal gasoline, 1000 barrels of polymer gasoline, and 1000 barrels of

C4= alkylate to produce a gasoline product having 10 psi Reid vapor pressure.

10. What is the posted octane number and Reid vapor pressure of the gasoline product of

problem 3?

11. Calculate the clear octane numbers (RON and MON) and the amount of butane needed

for a 12.0 psi RVP gasoline produced from the following:

BPSD

LSR naphtha 4,200 Light hydrocrackate 1,800 C5+ alkylate 4,500


28

Heavy hydrocrackate 9,150 Reformate (94 RON) 11,500 C5+ FCC gasoline 15,600

12. Recommend the best method (lowest capital cost) for increasing the posted octane

number of the pool gasoline in problem 11 by 5.5 octane numbers. Estimate the size of

the unit and its 1994 construction cost.

HW solve problems 3, 5, 6, 10

Chapter13 - valvBlending

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