Blending gasoline

7/25/2019 Blending gasoline

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Petroleum RefiningChapter 13: Product Blending

13-1

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- C

4

+Gases

Figure 13-1: Refinery gasoline blending


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Dr. Tareq Albahri, Chemical Engineering, Kuwait University, 2016

13-2

These gasoline blending-stocks have different molecular contents and performancequalities (RON, MON, RVP, API, BP range, etc.) as shown in Table 13-1.

They must be blended into various grades that meet market demands.

Blending components must meet all desired specifications like boiling point, specificgravity, RVP, research octane number (RON) and motor octane number (MON).

The products is designated off spec if it does not meet one or more of the requiredspecifications which could make it unsalable or salable for a lower price. Exceedingone or more of the required product specifications is termed giveaway, which is alsoa loss for the refinery because you are selling higher quality product for lower price.

Basic intermediate streams are usually blended to produce a variety of on-specfinished products. For example, naphtha can be blended into either gasoline or jetfuel, depending upon the product demand.

The objective of product blending is to allocate the available blending components insuch 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 (about65,000 BPCD), a saving of one-hundredth (1/100) of a cent per gallon results in anadditional profit of $100,000 per year.

Figure 13-2: Refinery tank farm blending & shipping farcicalities

Figure 13-3: Refinery blending facilities


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13-4

Blending for API gravity

API Gravities are not linear and therefore cannot be averaged.

Specific gravity can be volume Averaged.

Example 13-1: Blending for API

Calculate the API of a blend from1,000 bbls oil 70 API2,000 bbls oil 5 API

Solution:

= 141.5

131.5=

141.570 131.5

= 0.7026

= 141.5

131.5=

141.55131.5

= 1.0374

Ave. sp. gr. = 0.3333(0.7026) + 0.6666(1.0374) = 0.9258API = (141.5/ 0.9258)-131.5 = 21.34 If you average the API then the answer is = 0.3333 x 70 + 0.6666 x 5 = 26.67 X

Blending for Initial & Final BP

The initial boiling point of the blend equals the lowest of the blending stocks and thefinal boiling point equals the highest.

Example 13-2: Blending for Boiling Point

Calculate the initial and final boiling points of the blend from the following blending stocks,

LSR gasoline (C5180 F)HSR gasoline (200380 F)FCC gasoline (200300 F)Blend (C5380 F)

Blending for Reid Vapor Pressure (RVP)

The theoretical method for blending to the desired RVP requires knowledge of theaverage molecular weight of each of the streams.

A more convenient way developed by Chevron Research Company is to use VaporPressure Blending Indices (VPBI)compiled as a function of the RVP of the blendingstreams as shown inTable 13-3.

The RVP of the blend is closely approximated by the sum of all the products of thevolume fraction (Xv) times the VPBI for each blending component i.

13-1 (VPBI)blend= Xvi(VPBI)i

RVP of a gasoline is controlled by adding n-butane to (C5380F) naphtha. If the volume of the n-butane to be blended for a given RVP is given by,

13-2 V0(VPBI)0+ V1 (VPBI)1+ ... = (V0+V1+ ) (VPBI)m

whereV0= 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

13-3 RVPm1.25 = [V0(RVP0)

1.25+ V1(RVP1)1.25+ .]0.8/ total volume


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13-5

Table 13-3: Reid Vapor Pressure Blending Index Numbers for Gasoline and Turbine Fuels.

VaporPressure,

psi 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0123456789

1011121314151617181920

212223242526272829

0.001.002.373.945.657.479.3911.413.415.617.820.022.324.727.129.532.034.537.139.742.3

45.047.650.453.155.958.761.564.467.3

0.051.122.524.115.837.669.5811.613.715.818.020.322.624.927.329.832.234.837.339.942.6

45.247.950.653.456.259.061.864.767.6

0.131.252.674.286.017.859.7811.813.916.018.220.522.825.227.630.032.535.037.640.242.8

45.548.250.953.756.559.362.1I65.067.9

0.221.382.8344.46.198.049.9812.014.116.218.420.723.025.427.830.232.835.337.840.443.1

45.848.451.254.056.759.662.465.368.2

0.311.522.984.616.378.2310.212.214.316.418.720.923.325.628.030.533.035.538.140.743.4

46.048.751.554.257.059.862.765.668.4

0.421.663.144.786.558.4210.412.414.516.718.921.223.525.928.330.833.235.838.441.043.6

46.349.051.754.557.360.163.065.868.8

0.521.793.304.956.738.6110.612.614.716.919.121.423.726.128.531.033.536.038.641.243.9

46.649.352.054.857.560.463.366.169.0

0.641.943.465.136.928.8010.812.814.917.119.421.624.026.428.831.233.836.338.941.544.2

46.849.552.355.157.960.763.566.469.3

0.752.083.625.307.109.0011.013.015.217.319.621.924.226.629.031.534.036.639.141.844.4

47.149.852.655.358.161.063.866.769.6

0.872.233.785.487.299.1911.213.215.417.619.822.124.426.829.331.834.336.839.442.044.7

47.450.152.855.658.461.364.167.069.9

3040

70.2101

Example:Calculate the vapor-pressure of a gasoline blend as follows

(nC4) 51.6(iC4) 72.2(C3) 190.0

138210705

Component VolumeFraction

VaporPressure

psi

VaporPressureBlendingIndex No.

VolumeFraction

xVPBI

Equation:

VPBI = VP1.25

n-ButaneLight Straight RunHeavy RefinedTotal

0.0500.4500.5001.000

51.66.751.007.45

13810.91.0012.3

6.904.900.5012.3

From the brochure, 31.0API Iranian Heavy Crude Oil, by arrangement with ChevronResearch Company. Copyright 1971 by Chevron Oil Trading Company.


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13-6

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 trueoctane of the blend.

Blending octane numbers are based on experience. The formula used for calculations is:

Vblend(ON)blend= Vi(BON)iwhere,

Vblend= Total volume of gasoline blended (bbl).Vi= Volume of blending component i (bbl).(ON)blend= Desired true octane of blend.(BON)i= Blending octane number of component i.

If n-butane alone is not sufficient to increase thePool octane number of the gasoline,

different ways are used to improve the octane number. These are:1.

Increase severity of reforming to produce a 98.8 or 100 RONC reformate.(This is not attractive because the aromatics content of the gasoline would

increase and the volume would decrease).

2. Use octane improvers, such as MTBE or ETBE (Table 13-2)to improve thepool octane.

Example 13-3: Blending 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 an 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).

SolutionRVP values are obtained from Table 13.1VPBI values are obtained from Table 13.2

COMPONENT # (BPDi) (RVPi)

Table 13-1

(VPBIi)

Table 13-3

(BPDi)(VPBIi)

n-butane 2 W 52 139.64 139.64WHSR gasoline 8 1250 1.0 1.0 1250.00LSR gasoline 6 750 11.1 20.3 15225.00C5+FCC gasoline 18 620 4.4 6.37 3949.40

Total for blend 2620 + W 139.64W + 20424.4(BPDi) (BPDi)(VPBIi)

At 9.0 RVP, fromTable 13-3,(VPBI)m= 15.6

Into Equation13-1

(VPBI)m(BPDi) = (BPDi)(VPBIi)15.6 (2620 + W) = 20424.4 + 139.64 W

W = 165 BPD of n-butane


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13-7

b.Component # BPD Vol.

Frac.BMON

Table 13-1BRON

Table 13-1MON x

Vol. frac.RON x

Vol. frac.

n-butane 2 165 0.0592 92.0 93.0 4.85 5.51HSR 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 17.88C5+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. = 64.9RON of the blend = RON x vol. frac. = 71.9

10 % MTBE is equal to 0.1(2785 BPD) = 278.5 BPDMTBE octane number is fromTable 13-2.

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 5.022HSR gasoline 1250 0.408 58.7 62.3 23.95 25.42LSR gasoline 750 0.245 61.6 66.4 15.1 16.27C5FCC gasoline 620 0.202 76.8 92.3 15.51 18.64MTBE 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

BLENDING FOR OTHER PROPERTIES

Several methods exist for estimating the physical properties of a blend from those ofthe blending stocks.

One of the most convenient methods of estimating properties, that do not blendlinearly, is to substitute for the true value of the inspection to be blended anothervalue (called blending factor or index) which has the property of blendingapproximately linear.

The Chevron Research Company has compiled factors or index numbers for,Viscosities,Table 13-6Flash points,Table 13-7Aniline points, Error! Reference source not found.

Pour point, Error! Reference source not found.

Blending for Viscosity

Viscosity blending is more complicated than blending for the other properties.

It is not an additive property and it is necessary to use special techniques to estimatethe viscosity of a blend from the viscosities of its blending stocks.

The method most commonly accepted is the use of special charts developed by andobtainable from ASTM.

The viscosity factor of the blend can be calculated using the equation:(VF)blend= Xvi(VF)i

where, Xvi = Volume fraction.

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


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13-8

Blending of kinematic viscosities (centistokes, cSt = mm2/s) may be done at anytemperature, but the viscosities of all components of the blend must be at the sametemperature.

Blending of viscosities in Saybolt universal seconds also may be done at anytemperature and interchangeably with kinematic viscosities at the same temperature.

Table 13-6 may be used to convert viscosities expressed in centistokes (cSt) toSaybolt Universal Seconds (SUS) and vice versa.

Viscosity factors also are given inTable 13-6 for viscosities expressed in SayboltFurol Seconds(SFS).

Saybolt Furol viscosities are blended only at 122F. If SFS viscosities are at any othertemperature, they must be converted to centistokes or SUS before blending.

Viscosity factors for SFS at 122 F may be used interchangeably with viscosityfactors for SUS at 130 F and with centistokes at 130 F.

Table 13-6 may be used also to convert viscosities in SFS at 122 F to eitherkinematic or Saybolt Universal viscosities at 130 F.

Other viscosity units include- Redwood sec- Redwood Admiralty Seconds- Redwood No.1 Seconds

The viscosity of a blend can also be estimated by API Procedure 11A4.3 in the APITechnical Data Book - Petroleum Refining.

Blending for Flash Point

The flash point index of a blend is given by

(FPBI)blend= Xvi(FPBI)i

where

Xvi= Volume fraction.(FPBI)blend= Flash point blending index of the blend.(FPBI)i = Flash point blending index of component ifrom Table 13-5

Blending for Aniline Point

The aniline point index of a blend is given by

(APBI)blend= Xvi(APBI)iwhere

Xvi= Volume fraction.(APBI)blend= Aniline point blending index of the blend.(APBI)i = Aniline point blending index of component ifrom Table 13-6.

Blending for Pour Point

The pour point index of a blend is given by

(PP)blend= Xvi(PPBI)i

where Xvi= Volume fraction.(PP)blend= Pour point blending index of the blend.(PPBI)i = Pour point blending index of component i, from Table 13-7.


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13-9

Example 13-4Calculate the viscosity, flash point, aniline point, and pour point of the blend from the followingblending stocks.

Stock bbls ASTM 50%temp (F)

Viscosity Flash point(F)

Anilinepoint (F)

Pour point(F)

ABC

5,0003,0002,000

575425500

430 SFS at 120 F82.5 SUS at 130 F2.15 cSt at 130 F

10090130

70160

40 (mixed)

105065

Blend 10,000 ? ? ? ?

Solution:

a. Viscosity

Stock vol. frac.of blend

Viscosity Factor(Table 13-6)

vol. frac. xFactor

A

BC

0.5

0.30.2

430 SFS at 120 F

82.5 SUS at 130 F2.15 cSt at 130 F

0.700

0.5000.300

0.350

0.1500.060

Total 1 0.560

Table 13-6 gives the following viscosities for a blend with a factor of 0.5639.5 cSt at 130 F183 SUS at 130 F25.7 SFS at 122 F

b. Flash point

Stock vol. frac. of blend Flash point (F) Blending Index (

Table 13-7)vol. frac. x index

ABC

0.50.30.2

10090130

7531,170224

376.535144.8

Total 1 772

Table 13-7 gives a flash point for the blend of 99.5 F for a blending index of 772.

c. Aniline Point


Aniline point (F) Blending Index (Table13-6)

vol. frac. x index

A

BC

0.5

0.30.2

70

16040 (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 F or a mixedaniline point of 115 F.

d. Pour Point


ASTM 50%temp (F)

Pour Point (F) Blending Index(Table 13-7)

vol. frac. xindex

AB

C

0.50.3

0.2

575425

500

1050

65

861

98

418.3

19.6Total 1 41.9

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


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13-10

Notice that for the Octane number and the pour point the property (not the index) is

calculated, therefore, there is no need to go back to the Table to get the desired property.

Blending for Freezing point

The freezing point index of a blend is given by

(FPBI)blend= Xvi(FPBI)iwhere

Xvi= Volume fraction.(FPBI)blend= Freezing point blending index of the blend.(FPBI)i = Freezing point blending index of component ifrom Table.

Table 13-4. Freezing point blending index in Fahrenheit

Freeze Point (F) Index Freeze Point (F) Index Freeze Point (F) Freeze Point (F)

-250 0.0064 -105 1.2286 40 235.03

-245 0.0077 -100 1.4727 45 281.71

-240 0.0092 -95 1.7651 50 337.66

-235 0.0111 -90 2.1157 55 404.72

-230 0.0133 -85 2.5359 60 485.11

-225 0.0159 -80 3.0396 65 581.46

-220 0.0190 -75 3.6433 70 696.94

-215 0.0228 -70 4.3669 75 835.37

-210 0.0274 -65 5.2343 80 1001.3

-205 0.0328 -60 6.2739 85 1200.2

-200 0.0393 -55 7.5199 90 1438.5

-195 0.0471 -50 9.0135 95 1724.2

-190 0.0565 -45 10.804 100 2066.7

-185 0.0677 -40 12.949 105 2477.2

-180 0.0811 -35 15.521 110 2969.2

-175 0.0973 -30 18.604 115 3558.9

-170 0.1166 -25 22.299 120 4265.7

-165 0.1397 -20 26.728 125 5112.9-160 0.1675 -15 32.037 130 6128.4

-155 0.2007 -10 38.400 135 7345.6

-150 0.2406 -5 46.026 140 8804.6

-145 0.2884 0 55.168 145 10553.3

-140 0.3457 5 66.125 150 12649.3

-135 0.4143 10 79.258 155 15161.6

-130 0.4966 15 95.000 160 18173.0

-125 0.5953 20 113.87 165 21782.4

-120 0.7135 25 136.48 170 26108.7

-115 0.8552 30 163.59 175 31294.2

-110 1.0250 35 196.08

Courtesy Albahri 2015


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13-11

Table 13-5 Freezing point blending index in Kelvin

Freeze Point (K) Index Freeze Point (K) Index Freeze Point (K) Index

116 0.0061 196 1.139 276 210.1

118 0.0070 198 1.297 278 238.8

120 0.0080 200 1.473 280 272.4122 0.0091 202 1.683 282 310.8

124 0.0104 204 1.919 284 353.8

126 0.0119 206 2.183 286 402.0

128 0.0135 208 2.486 288 459.4

130 0.0154 210 2.838 290 523.6

132 0.0175 212 3.233 292 595.3

134 0.0200 214 3.672 294 678.5

136 0.0227 216 4.193 296 774.5

138 0.0259 218 4.783 298 881.8

140 0.0295 220 5.442 300 1001.3142 0.0336 222 6.191 302 1144.5

144 0.0383 224 7.071 304 1305.0

146 0.0437 226 8.058 306 1484.2

148 0.0497 228 9.157 308 1689.9

150 0.0565 230 10.45 310 1929.7

152 0.0646 232 11.92 312 2198.0

154 0.0736 234 13.57 314 2496.8

156 0.0837 236 15.42 316 2851.1

158 0.0953 238 17.62 318 3252.2

160 0.1088 240 20.08 320 3700.2

162 0.1240 242 22.83 322 4209.2

164 0.1408 244 26.02 324 4807.9

166 0.1608 246 29.70 326 5478.5

168 0.1834 248 33.82 328 6225.8

170 0.2087 250 38.40 330 7102.2

172 0.2374 252 43.89 332 8104.3

174 0.2712 254 50.05 334 9224.3

176 0.3090 256 56.92 336 10483

178 0.3512 258 64.81 338 11979

180 0.4006 260 74.01 340 13654

182 0.4571 262 84.30 342 15523

184 0.5203 264 95.75 344 17691

186 0.5913 266 109.3 346 20194

188 0.6756 268 124.7 348 22994

190 0.7702 270 141.9 350 26109

192 0.8756 272 161.4 352 29842

194 0.9979 274 184.4 354 33576

Blending for Smoke point

The smoke point of a blend is given by


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13-12

(SP)blend= Xvi(SP)iwhere

Xvi= Volume fraction.(SP)blend= Smoke point blending index of the blend.

(SP)i = Smoke point blending index of component i

Example 13-5

Calculate the freezing point and smoke point of the blend from the following kerosene blendingstocks.

Stock bbls Freezing point (F) Smoke Point (mm)

ABC

5,0003,0002,000

-55-50-51

252221

Blend 10,000 ? ?

Solution:

Freezing Point (F) using table


Freezing point (F) Freezing Pointblending index

vol. frac. x index

ABC

0.50.30.2

-55-50-51

7.51999.01358.6928

3.76002.70411.7386

Total 1 8.2027

Table gives a freezing point of -52.7 F for a blend with a factor of 8.2027

In terms of equations

British units

FPBIFi= 55.16793 (1.0368976)FPFiFPBIm= Xvi(FPBI)iFPFm= -111.1628+27.68212 ln (FPBIm)

FPFi= freezing point of component i in F

FPFm= freezing point of the blend in FFPBIi = freezing point blending index for component iFPBIm= freezing point blending index for the blendXvi= volume fraction of component i

Freezing Point (F) using equations


Freezing point (F) Freezing Pointblending index

vol. frac. x index

ABC

0.50.30.2

-55-50-51

7.51999.01358.6928

3.76002.70401.7386

Total 1 8.2026

Equation gives a freezing point of -52.9 F for a blend with a factor of 8.2026


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13-13

In SI units

FPBIFi= 55.16793 (1.0368976)FPFi

FPBIm= Xvi(FPBI)iFPFm= -111.1628+27.68212 ln (FPBIm)

FPFi= freezing point of component i in FFPFm= freezing point of the blend in FFPBIi = freezing point blending index for component iFPBIm= freezing point blending index for the blendXvi= volume fraction of component i

Freezing Point (K) using table

Stock vol. frac.

of blend

Freezing point (K) Freezing Point

blending index

vol. frac. x index

ABC

0.50.30.2

225227.8227.2

7.51999.02788.7028

3.76002.70831.7406

Total 1 8.2089

Table gives a freezing point of 226.3 K (-52.7 F) for a blend with a factor of 8.2026

Freezing Point (K) using equation


Freezing point (K) Freezing Pointblending index

vol. frac. x index

ABC

0.50.30.2

-225227.8227.2

7.55809.07128.7233

3.77902.72141.7447

Total 1 8.2450

Equation gives a freezing point of 226.2 K (-52.8 F) for a blend with a factor of 8.2026

Smoke pointStock vol. frac.

of blendSmoke Point

(mm)Smoke Point x

vol. frac.

ABC

0.50.30.2

252221

12.56.64.2

Blend 1 23.3

The smoke point of the blend is 23.3 mm


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13-14

Numerical Method for blending viscosity

Table 13-6 maybe digitized and the following equations are obtained,

For blend no. 1

X1= log10(visc.1) (1)

for viscosity in centistokesuse the following Rational function

= 0.17 0.5238

1 0.5124 0.01233

(2)

or

= (X1+ 0.3103)/10

= 0.291694 .

= 1.05593 (3)

for the viscosity in SUS use one of the following two equations

= 0.6068 0.047970.80755

(4)

or

= 97993438 103852082 1 118310078 3052999

(3)

or

VF1= 0.5909 (X1-1.4414)0.25372

for viscosity in SFSuse

VF1= 0.5008X10.345 (5)

For blend no. 2, use the above equations 1 through 4. For example, Equations 1 and 2 wouldbecome,

X2= log10(visc.2)

= 0.17 0.5238

1 0.5124 0.01233

The viscosity factor for the blend


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13-15

1 1 2 2

1 2

V VF V VF ...

V V ...blend

VF

(6)

To calculate the viscosity of the blend in cSt

log. = 0.3148 1.796

1 1.26376 0.4498

(7)

To calculate the viscosity of the blend in SUS use either of the following equations

log. =5.2602 34.83 .

3.7246 .

(8)

log(visc.blend) = 21.0553 -19.6471 exp[-0.446654(VFblend)3.9315] (9)

log. = 1.4123 33.4177 .

3.7246 .

(10)

To calculate the viscosity of the blend in SFS

Log(visc.blend) = 13.07836 -12.6188 exp [-0.7749(VFblend)3.9578] (11)

Example 13-6:Blending for viscosity using above (Albahri Viscosity Blending equations)

visc.i VFi Vi vol frac x factor

500 0.691 0.3333 0.230300 0.669 0.3333 0.223200 0.651 0.3334 0.217

Total 0.670

Log (viscblend) = 2.503 Visc = 318 cSt

Using tabular method



vol. frac. xFactor

ABC

0.33330.33330.3334

500 cSt at 130 F300 cSt at 130 F200 cSt at 130 F

0.6890.6630.648

0.2300.2210.216

Total 1 0.667

Table 13-6 gives 300 cSt at 130 F for a blend with a factor of 0.667


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13-16

Example 13-7:Blending for viscosity using above (Albahri Viscosity Blending equations)

visc.i VFi Vi vol frac x factor

500 0.691 0.3333 0.230

300 0.669 0.3333 0.223200 0.651 0.3334 0.217

Total 0.670

Log (viscblend) = 2.503 Visc = 318 cSt

Using tabular method



vol. frac. xFactor

AB

C

0.33330.3333

0.3334

500 cSt at 130 F300 cSt at 130 F

200 cSt at 130 F

0.6890.663

0.648

0.2300.221

0.216Total 1 0.667

Table 13-6 gives 300 cSt at 130 F for a blend with a factor of 0.667

Example 13-8: Convert the viscosity of an oil sample having 100 cSt to SUS and SFS

Solution: From theTable 13-6 the viscosity factor for 100 cSt is 0.613. This factorcorresponds to 460 SUS and 62 SFS at 122 F.

Numerical Method

From equation (3) get the viscosity factor

X1 = log (vcSt) = log (100) = 2

= (X1+ 0.3103)/10 = 0.23103

= 0.291694 .= 0.3709

= 1.05593 = 0.61319

Then use equation (9) to get the viscosity in SUS

log(visc.blend) = 21.0553 -19.6471 exp[-0.446654(VFblend)3.9315] (9)

log(visc.blend) = 21.0553 -19.6471 exp[-0.446654(0.61319)3.9315] = 2.65visc = 446.8 SUS

Use equation (11) to get the viscosity in SFS

log(visc.blend) = 13.07836 -12.6188 exp [-0.7749(VFblend)3.9578] (11)

log(visc.blend) = 13.07836 -12.6188 exp [-0.7749(0.61319)3.9578] = 1.79477

visc= 62.34 SFS


17/32


13-17

An alternate numerical method for calculating the pour point of distillate blending stocks.

The pour point blending index is given by the following equations instead of Table

In kelvin

PPBI(K)i=255.565 + 4.9021110-6exp [-0.016418 (PPK) - 0.0522346 (TbK)+ 1.575110-4(PPK)(TbK)] (PPK)1.67057(TbK)2.37162

PPBI(K)i = pour point blending index for component iin KelvinPPK= pour point in kelvinTbK= ASTM distillation curve 50% temperature in kelvin (average boiling point)

In Fahrenheit

PPBIFi= 0.1786 + 0.425117 exp [0.0147 (PPF+70) - 0.00887 (TbF) + 4.92510-5 (PPF+70)(TbF)](PPF+70)0.1894(TbF)0.5855

PPBIFi= pour point blending index for component iin FPPFis pour point in FTbF= ASTM distillation curve 50% temperature in F (average boiling point)

The procedure is to calculate the PPBI for each component using the equation then add to obtain thepour point of the blend

PP = XviPPBIKi

Example 13-9

Applied to the previous example to calculate the pour point, the above equations will yield,

d. Pour Point (F eqn)

Stockvol. frac. Pour Point

(F)ASTM 50% temp

(F)Blending Index (Table

13-7)vol. frac. x

indexof blend

A 0.5 10 575 7.8 3.92

B 0.3 50 425 60.6 18.17

C 0.2 65 500 98.3 19.66

Total 1 41.8

d. Pour Point (K eqn)

Stock

vol.frac.

PourPoint(F)

ASTM 50%temp (F)

PourPoint(F)

ASTM 50%temp (K)

Blending Index(Table 13-7)

vol. frac.x index

ofblend

(F) (K)

A 0.5 10 575 261.1 575.0 259.90 129.95

B 0.3 50 425 283.3 491.7 289.16 86.75C 0.2 65 500 291.7 533.3 310.27 62.05

Total 1 278.8


18/32


13-18

41.8

An alternate method for calculating the flash point of blending stocks.

The flash point blending index is given by the following equations instead of the Table

In British units: (FPBI)i= (0.3792866 + 2.085510-3FPFi)-12.4108

In SI Units: (FPBI)i= (-0.5800437+ 3.753910-3FPKi)-12.4108

FPFi = Flash point of component i in FFPKi = Flash point of component i in KelvinXvi= volume fraction of component i(FPBI)m= Flash point index for the blend

(FPBI)m= Xvi(FPBI)i

The flash point is then calculated for the blend using the following equations

In British units: FPFm= [327.0522-27.1872 ln(FPBIm)]/[1+ 0.071016 ln(FPBIm)-2.766222-5ln(FPBIm)2]

In SI units: FPKm= [437.250592356+ 4.0809276 ln(FPBIm)]/[1+ 0.0733857193 ln(FPBIm)+1.40131821823232-4ln(FPBIm)2]

FPF = flash point of the blend in degrees FFPK = flash point of the blend in K

Example 13-10

Applied to the previous example to calculate the flash point, the above equations will yield,

b. Flash point (F)

Stock vol. frac. of blend Flash point (F) Blending Index (Table 13-5) vol. frac. x index

A 0.5 100 730.7 365.3

B 0.3 90 1143.9 343.2

C 0.2 130 208.2 41.6

Total 1 750.2

from eqn Flash = 100.1 F

Flash point (K)

Stockvol. frac. of

blend

Flash point

(K)

Blending Index

(Table 13-5)vol. frac. x index

A 0.5 311.1 730.7 365.3

B 0.3 305.6 1144.0 343.2

C 0.2 327.8 208.2 41.6

Total 1 750.2

from eqn Flash = 311.2 K or 100.1 F


19/32


13-19

An alternate numerical method for calculating the aniline point of distillate blending stocks.

The aniline point blending index is given by the following equations instead of the Table

In British units:

APBIi= 49.11 (1 + 0.05 APFi)1.3004

In SI Units:

APBIi= 4852.435 + 14.7655APKi+

(more accurate)

APBIi= 1437.69 + 1618.79 COS (0.007435 APKi+ 1.7832)

where

APFi = Aniline point of component i in FAPKi = Aniline point of component i in KelvinXvi= volume fraction of component iAPBIm= Aniline point index for the blend

APBIm= XviAPBIi

The aniline point is then calculated for the blend using the following equations

In British units:

APFm=(+. APBI.)

.+APBI. 32

In SI units:

APKm=(+ APBI

.)

(+APBI.)

(more accurate)

APKm= 2427.82 2182.923 exp ( 0.0002259 (APBIm)0.7898)

APF = Aniline point of the blend in FAPK = Aniline point of the blend in K

An alternate numerical method for calculating the mixed aniline point of distillate blendingstocks.

The mixed aniline point blending index is given by the following equations instead of theTable

In British units:

MAPBIi=1090 + 2221 cos (0.005425 MAPFi+ 3.7453) (more accurate)


20/32


13-20

MAPBIi=.+.

(.+.)

In SI Units use one for the following equations:

MAPBIi= - 10323.5 + 29.064 MAPKi+

(more accurate)

MAPBIi=.+.

(.+.)

1000

MAPBIi= 1090.1 + 2221.5 cos (0.009764 MAPKi+1.2502)

where

MAPFi= Mixed aniline point of component i in FMAPKi= Mixed aniline point of component i in KelvinXvi= volume fraction of component iMAPBIm= Mixed aniline point index for the blend

MAPBIm= XviMAPBIi

The mixed aniline point for the blend is calculated using the following equations

In British units:

MAPFm=.+.

(+.. )

In SI units:

MAPKm=

.+. n+.n+ (more

accurate)

MAPKm=

(...)

MAPKm= .+. +[+.+.+ ]

MAPKm=(+ MAPBI+

.)

(+MAPBI+.)

(least accurate)


21/32


13-21

Example 13-11

Applied to the previous example to calculate the aniline point, the above equations will yield,

Aniline point (F)

Stock vol. frac. of blend Aniline point (F) Blending Index (Eq.) vol. frac. x indexA 0.5 70 347.2 173.6

B 0.3 160 855.2 256.6

C 0.2 40 (mixed) -424.1 -84.8

Total 1 345.4

from eqn. aniline point = 69.6 F from eqn. mixed aniline point = 115.2 F

Aniline point (K)

Stock vol. frac. of blend Aniline point (K)

Blending Index

(Eq.) vol. frac. x index

A 0.5 294.4 346.2 173.1

B 0.3 344.4 855.3 256.6

C 0.2 277.8 -242.0 -84.8

Total 1 344.9

from eqn. aniline point = 294.2 K or 69.5 F from eqn. mixed aniline point = 319.6 K or 115.3 F

Real blending industrial example

Example 13-12:Calculate the amount of each blending stock that would produce a 300,000 bbls gasoline

product with the flowing specifications, API = 70 min, ON = 95 min, RVP = 9 maxAvailable blends are as follows

Component bbls API ON RVP SG RVPI = RVP1.25

Tank 1 Reformate 500,000 70 94 10 0.7022 17.7828Tank 2 Isomerate 400,000 69 92 9 0.7057 15.5885Tank 3 Alkylate 600,000 72 96 8 0.6953 13.4543

Desired Blend 300,000 70 95 9 0.7022 15.5885

Solution:

LetN1 = bbls of Tank 1 reformateN2 = bbls of Tank 2 isomerateN3 = bbls of Tank 3 alkylate

Objective function N1 + N2 + N3 = 300,000

Constraints:

N1 500,000N2 400,000N3 600,000


22/32


23/32


13-23

Table 13-6: Viscosity Blending Index Numbers

Factors for Volume Blending of Viscosities at Constant Temperatures Corresponding tovalues 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

0.50.60.70.80.9

0.0000.0560.0970.1280.154

0.0060.0610.1000.1310.156

0.0130.0650.1040.1340.159

0.0190.0690.1070.1370.161

0.0250.0740.1100.1390.163

0.0300.0780.1140.1420.165

0.0360.0820.1170.1440.167

0.0410.0860.1200.1470.169

0.0460.0890.1230.1490.172

0.0510.0930.1260.1520.174

cSt0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

123456789

0.1760.2900.3420.3750.3980.4160.4310.4430.453

0.1940.297

0.3460.3780.4000.4180.4320.4440.454

0.2100.303

0.3500.3800.4020.4190.4330.4450.455

0.2240.3090.3530.3830.4040.4210.4340.4460.456

0.2360.3140.3570.3850.4060.4220.4360.4470.456

0.2470.3200.3600.3870.4080.4230.4370.4480.457

0.2570.3250.3630.3900.4100.4250.4380.4490.458

0.2660.3290.3660.3920.4110.4260.4390.4500.459

0.2750.3340.3690.3940.4130.4280.4400.4510.460

0.2830.3380.3720.3960.4140.4290.4420.4520.461

cSt0 1 2 3 4 5 6 7 8 9

1020304050607080

90

0.4620.5150.5430.5610.5750.5850.5940.601

0.608

0.4700.5190.5450.5630.5760.5860.5950.602

0.608

0.4770.5220.5470.5640.5770.5870.5960.603

0.609

0.4830.5250.5490.5660.5780.5880.5960.603

0.610

0.4890.5280.5510.5670.5790.5890.5970.604

0.610

0.4940.5310.5530.5680.5800.5900.5980.605

0.611

0.4990.5330.5550.5700.5810.5910.5990.605

0.611

0.5030.5360.5570.5710.5820.5920.5990.606

0.612

0.5080.5380.5580.5720.5830.5920.6000.607

0.612

0.5110.5410.5590.5730.5840.5930.6010.607

0.613

cSt0 10 20 30 40 50 60 70 80 90

100200300400500600

700800900

0.6130.6480.6670.6800.6890.697

0.7030.7080.713

0.6180.6510.6690.6810.6900.698

0.7040.7090.714

0.6230.6530.6700.6820.6910.698

0.7040.7090.714

0.6270.6550.6710.6830.6920.699

0.7050.7100.715

0.6310.6570.6730.6840.6920.700

0.7050.7100.715

0.6340.6590.6740.6850.6930.700

0.7060.7110.715

0.6370.6610.6750.6860.6940.701

0.7060.7110.716

0.6400.6620.6760.6870.6950.701

0.7070.7120.716

0.6430.6640.6780.6880.6960.702

0.7070.7120.716

0.6460.6660.6790.6880.6960.702

0.7080.7130.717


24/32


13-24

cSt0 100 200 300 400 500 600 700 800 900

1,0002,0003,0004,0005,0006,0007,0008,0009,000

0.7170.7430.7570.7670.7750.7800.7850.7900.793

0.7210.7450.7580.7680.7750.7810.7860.7900.794

0.7240.7470.7590.7690.7760.7810.7860.7900.794

0.7270.7480.7610.7700.7770.7820.7870.7910.794

0.7300.7500.7620.7700.7780.7820.7870.7910.795

0.7330.7510.7630.7710.7780.7830.7870.7910.795

0.7350.7520.7640.7720.7780.7830.7880.7920.795

0.7370.7540.7650.7720.7790.7840.7880.7920.796

0.7390.7550.7650.7730.7790.7840.7890.7920.796

0.7410.7560.7660.7740.7800.7850.7900.7930.796

cSt0 1000 2000 3000 4000 5000 6000 7000 8000 9000

10,00020,00030,00040,00050,00060,00070,00080,00090,000

0.7960.8170.8280.8360.8420.8470.8510.8540.858

0.7990.8180.8290.8370.8430.848

0.8020.8200.8300.8380.8430.848

0.8040.8210.8310.8380.8440.848

0.8060.8220.8320.8390.8440.849

0.8080.8230.8330.8390.8450.849

0.8100.8240.8330.8400.8450.850

0.8120.8250.8340.8410.8460.850

0.8140.8260.8350.8410.8460.850

0.8150.8270.8360.8420.8470.851

cSt cSt cSt

100,000200,000300,000400,000500,000600,000700,000800,000900,000

0.8600.8770.8870.8940.8990.9030.9060.9090.912

1,000,0002,000,0003,000,0004,000,0005,000,0006,000,0007,000,0008,000,0009,000,000

0.9140.9280.9370.9420.9470.9500.9530.9560.958

10,000,00020,000,00030,000,00040,000,00050,000,00060,000,00070,000,00080,000,00090,000,000

0.9600.9730.9800.9850.9890.9920.9950.9970.999


25/32


13-25

Factors for Volume Blending of Viscosities at Constant Temperatures Corresponding tovalues of Saybolt Universal Seconds (SUS).

SUS0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

3233343536373839

0.2750.2960.3140.3280.3420.3530.3630.373

0.2780.2980.3150.3300.3430.3540.3640.373

0.2800.3000.3170.3310.3440.3550.3650.374

0.2820.3020.3180.3330.3450.3560.3660.375

0.2840.3030.3200.3340.3460.3570.3670.376

0.2860.3050.3210.3350.3470.3580.3680.377

0.2880.3070.3230.3370.3490.3590.3690.378

0.2900.3090.3240.3380.3500.3600.3700.378

0.2920.3100.3260.3390.3510.3620.3710.379

0.2940.3120.3270.3400.3520.3630.3720.380

SUS0 1 2 3 4 5 6 7 8 9

405060708090

0.3810.4350.4640.4830.4970.508

0.3880.4390.4660.4850.4980.509

0.3950.4420.4690.4860.499

0.510

0.4020.4450.4710.4880.501

0.511

0.4080.4490.4730.4890.5020.512

0.4130.4510.4750.4910.5030.513

0.4180.4540.4760.4920.5040.513

0.4230.4570.4780.4930.5050.514

0.4280.4590.4800.4950.5060.515

0.4310.4620.4820.4960.5070.516

SUS0 10 20 30 40 50 60 70 80 90

100200300400500600700800

900

0.5170.5650.5890.6050.6170.6270.6350.641

0.647

0.5240.5680.5910.6070.6180.6280.6350.642

0.647

0.5310.5710.5930.6080.6190.6280.6360.642

0.648

0.5370.5740.5950.6090.6200.6290.6370.643

0.648

0.5420.5760.5960.6110.6210.6300.6370.643

0.649

0.5470.5790.5980.6120.6220.6310.6380.644

0.649

0.5510.5810.6000.6130.6230.6320.6390.645

0.650

0.5550.5830.6010.6140.6240.6320.6390.645

0.650

0.5590.5850.6030.6150.6250.6330.6400.646

0.651

0.5620.5870.6040.6160.6260.6340.6400.646

0.651


26/32


13-26

SUS0 100 200 300 400 500 600 700 800 900

1,0002,0003,0004,0005,0006,0007,0008,0009,000

0.6520.6830.7000.7110.7200.7270.7330.7380.742

0.6560.6850.7010.7120.7210.7280.7330.7380.742

0.6600.6870.7030.7130.7220.7280.7340.7390.743

0.6640.6890.7040.7140.7220.7290.7340.739

0.743

0.6670.6910.7050.7150.7230.7290.7350.7400.744

0.6700.6920.7060.7160.7240.7300.7350.7400.744

0.6730.6940.7070.7170.7250.7310.7360.740

0.744

0.6760.6960.7080.7180.7250.7310.7360.7410.745

0.6780.6970.7090.7190.7260.7320.7370.7410.745

0.6810.6990.7100.7190.7260.7320.7370.7420.745

SUS

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

10,00020,00030,00040,00050,00060,000

0.7460.7700.7830.7920.7990.804

0.7490.7710.7840.7930.7990.805

0.7520.7730.7850.7930.8000.805

0.7550.7740.7860.7940.8000.806

0.7580.7760.7870.7950.8010.806

0.7600.7770.7880.7950.8020.807

0.7620.7780.7890.7960.8020.807

0.7640.7790.7900.7970.8030.807

0.7660.7810.7900.7970.8030.808

0.7680.7820.7910.7980.8040.808

SUS SUS SUS SUS

70,00080,00090,000

0.8090.8130.816

100,000200,000300,000400,000500,000600,000700,000800,000900,000

0.8190.8380.8490.8560.8620.8670.8700.8740.877

1,000,0002,000,0003,000,0004,000,0005,000,0006,000,0007,000,0008,000,0009,000,000

0.8790.8950.9040.9110.9150.9190.9230.9250.928

10,000,00020,000,00030,000,00040,000,00050,000,00060,000,00070,000,00080,000,00090,000,000

0.9300.9440.9520.9570.9610.9650.9680.9700.972


27/32


13-27

Factors for Volume Blending of Viscosities at 130 F corresponding to values of SayboltFurol Seconds (SFS) at 122 F.

SFS at122 F 0 1 2 3 4 5 6 7 8 9

2030405060708090

0.5700.5880.6010.6110.6190.6260.632

0.5720.5900.6020.6120.6200.6270.633

0.5740.5910.6040.6130.6210.6270.633

0.5760.5930.6050.6140.6220.6280.634

0.5780.5940.6060.6150.6220.6290.634

0.5580.5800.5950.6070.6160.6230.6290.635

0.5610.5820.5970.6080.6160.6240.6300.635

0.5630.5840.5980.6090.6170.6240.6300.636

0.5660.5850.5990.6100.6180.6250.6310.636

0.5680.5870.6000.6100.6190.6260.6320.637

SFS at122 F 0 10 20 30 40 50 60 70 80 90

100200300400500600700800900

0.6370.6690.6860.6970.7060.7130.7190.7240.728

0.6420.6710.6870.6980.7070.7130.7190.7240.728

0.6460.6730.6880.6990.7070.7140.7200.7240.729

0.6490.6750.6890.700

0.7080.7150.7200.7250.729

0.6530.6760.6910.7010.7090.7150.7210.7250.729

0.6560.6780.6920.7020.7100.7160.7210.7260.730

0.6590.6800.6930.7030.7100.7160.7220.7260.730

0.6610.6810.6940.7030.7110.7170.7220.7270.730

0.6640.6830.6950.7040.7120.7180.7230.7270.731

0.6660.6840.6960.7050.7120.7180.7230.7270.731

SFS at122 F 0 100 200 300 400 500 600 700 800 900

100020003000

0.7320.7550.769

0.7350.7570.770

0.7380.7590.771

0.7410.7600.772

0.7430.7610.773

0.7460.7630.773

0.7480.7640.775

0.7500.7640.775

0.7520.7660.776

0.7540.7670.777

400050006000700080009000

0.7780.7840.7900.7950.7980.802

Notes:Values from this table are for 130 F, although the Saybolt Furol seconds are at122 F. This table alone must not be used for any other temperatures. Valuesfrom this table may be used interchangeably with values for kinematic andSaybolt Universal viscosities if the latter are for 130 F.

For SFS at 210 F, assume SUS10 x SFS and use the Saybolt Universal table.


28/32


13-28

Table 13-7: Flash Point Blending Index Numbers.Flash Point,

F 0 1 2 3 4 5 6 7 8 9

0

10

20

3040

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

25,20014,200

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

23,80013,500

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

22,40012,700

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

21,20012,000

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

20,00011,400

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

18,90010,800

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

17,80010,200

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

16,8009,680

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

15,9009,170

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

15,0008,690

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.


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Table 0-1: Aniline Point Blending Index Numbers.Aniline Point,

F0 -1 -2 -3 -4 -5 -6 -7 -8 -9

-100

20.049.1

17.446.0

14.942.8

12.639.8

10.336.8

8.1033.8

6.0630.9

4.1728.1

2.4625.3

1.0022.6

Aniline Point,F

0 1 2 3 4 5 6 7 8 9

0102030405060708090

100110120130140150160170180

190200210220230240

49.183.2121162205250298347398451505560617674733794855917980

1,0441,1101,1761,2421,3101,379

52.486.8125166209255303352403456510566622680739800861923986

1,0501,1161,1821,2491,3171,386

55.690.5129170214260308357408461516571628686745806867930993

1,0571,1221,1891,2561,3241,392

58.994.2133174218264312362414467521577634692751812873936999

1,0641,1291,1961,2621,3311,400

62.397.9137179223269317367419472527582640698757818880942

1,006

1,0701,1361,2021,2691,3371,406

65.7102141183227274322372424477532588645704763824886948

1,012

1,0771,1421,2091,2761,3441,413

69.1105145187232279327377429483538594651710769830892955

1,019

1,0831,1491,2161,2831,3511,420

72.6109149192237283332382435488543599657716775836898961

1,025

1,0901,1561,2221,2901,3581,427

76.1113153196241288337388440494549605663722781842904967

1,031

1,0961,1621,2291,2971,3651,434

79.6117157200246293342393445491554611669727788849911974

1,038

1,1031,1691,2361,3031,3721,441

Mixed AnilinePoint, F 0 1 2 3 4 5 6 7 8 9

010

2030405060708090

100110120

130140

-736-668

-593-511-425-334-239-140-38.366.8175285399

514632

-730-660

-584-503-416-324-229-130-27.977.4186297410

526644

-723-653

-577-494-407-315-219-120-17.588.1197308422

538656

-716-646

-569-486-398-306-210-110-7.0698.8208319433

550668

-709-639

-561-477-389-296-200-1003.39110219330445

561680

-703-631

-552-468-380-287-190-89.613.9120230342456

573692

-696-623

-544-460-371-277-180-79.424.4131241353468

585704

-689-616

-536-451-361-267-170-69.235.0142252364479

597716

-682-608

-528-442-352-258-160-58.945.5153263376491

609728

-675-600

-519-433-343-248-150-48.656.1164274387503

620741


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Table 0-2: Pour Point Blending Indices for Distillate StocksASTM 50% Temp

300 350 375 400 425 450 475 500 525 550 575 600 625 650 675 700

PourPoint

7065605550454035302520151050

-5-10-15-20-25-30-35-40-45-50-55-60-65-70

13311499887260524437322723201714

12108.87.56.45.54.64.03.32.82.52.11.81.5

13111194796856484134292420171512

108.87.46.35.34.53.73.22.72.31.91.61.41.1

12910992776654463932272319161411

9.58.06.85.74.74.03.32.82.42.01.71.41.20.99

12810790756352443731262118151310

8.77.36.15.14.23.62.92.52.11.71.41.21.00.84

1271058773615042352924201714129.6

8.06.65.54.63.73.22.62.21.81.51.21.00.850.71

1251038571594840332723191613118.7

7.25.94.94.13.32.82.31.91.51.31.10.870.720.60

12310182685646383226211714129.77.9

6.55.34.43.62.92.42.01.61.31.10.900.740.600.50

1209880665444363024201613118.87.1

5.84.73.93.22.52.11.71.41.10.930.770.620.500.42

11896776352423428231815129.87.96.3

5.14.13.42.82.21.81.41.20.980.780.650.520.410.36

11594746149403226211714118.87.15.6

4.53.63.02.41.91.51.21.00.820.660.550.430.340.30

11391725847383024191512108.06.35.0

3.93.22.62.11.71.31.00.860.680.560.460.360.280.25

110886956443528231814119.07.15.64.4

3.42.82.21.81.41.10.900.730.580.470.370.300.230.20

108856753423326211613108.16.35.03.8

3.02.51.91.51.20.960.750.620.480.380.300.240.180.15

1058264503931241915129.17.25.64.43.4

2.72.21.71.31.00.800.620.510.380.310.240.190.140.11

1037962483729221814118.36.45.03.83.0

2.41.91.41.10.900.670.510.410.310.250.190.140.100.08

1007660463527211613107.55.84.53.52.7

2.11.61.20.940.720.560.430.330.250.200.150.100.070.05

From Gary & Handwerk

Online Blending

Because of limited storage space, many refineries today (MAB refinery) have theability to use computer-controlled in-line product blending.

Inventories of blending stocks, together with cost and physical property data aremaintained in the computer.

When a certain volume of a given quality product is specified, the computer useslinear programming models to optimize the blending operations (select the optimumvolume 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 areinstalled 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 (iterative) procedure which is easily handled by a computer.

The large number of variables leads to a number of equivalent solutions that give theapproximate equivalent total overall cost or profit.

Optimization programs (like PIMS for example) permit the computer to provide theoptimum blend to minimize cost and maximize profit.

Both linear and nonlinear programming techniques are used.


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Nonlinear programming is preferred if sufficient data are available to define theequations because components blend non-linearly and values are functions of thequantities of the components and their properties (specs).

Figure 13-4: Refinery online blending facilities

Figure 13-5: Schematic representation of the online blending system for diesel product

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 C5FCC 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 of2730 barrels of LSR gasoline, 2490 barrels of 94 RON reformate, 6100 barrels of heavyhydrocrackate, 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 flashpointof 120F,3750 barrels with a flashpointof 35F, and 5000 barrels with a 150F flashpoint?

5.

Calculate the pour point of the following mixture:


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Compone

Barrel

ASTM50%

Pourpoint,

A 5,200 57

10

B 3 000 42

50C 6 500 50

65

D 3,250 55 45

6. What is the viscosity of a blend of 2000 barrels of oil with a viscosity of 75.5 cSt at 130F,3000 barrels with 225 cSt at 130F, and 5000 barrels with 6500 cSt at 130F?

7. Calculate the octane numbers of the final blend and amount of n-butane needed forproducing 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 ofC4= 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 ofproblem 3?

11. Calculate the clear octane numbers (RON and MON) and the amount of butane needed fora 12.0 psi RVP gasoline produced from the following:

Belding component BPSD

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

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

12. Recommend the best method (lowest capital cost) for increasing the posted octane numberof the pool gasoline in problem 11 by 5.5 octane numbers. Estimate the size of the unitand its 1994 construction cost.

HW solve problems 3, 5, 6, 10

Blending gasoline

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