(Blending Manual)ll

Form code : MDT.GG.QUA.0508 Sh. 01/Rev. 1.94 File code: Normal.dot Data file:PRG_PT_GEN_0001_R00_E_F.DOCCONFIDENTIAL document. Sole property of 6QDPSURJHWWL. Not to be shown to Third parties or used for purposes other than those for which it has been sent.

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Rev. 0 Date Nov. 1998

Sheet 2 (47)


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1.1 Scope And Application Field 6

1.2 References 6

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2.1 Characterization of Petroleum Fractions 6

2.1.1 Characterization Factor 6

2.2 Heat of Combustion Estimation 10

2.3 Flash Point Estimation 11

2.4 Viscosity Estimation 12

2.5 Aniline Point Estimation 13

2.6 Cetane Number Estimation 14

2.7 Pour Point Estimation 14

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3.1 Definitions 15

3.2 Summary 15

3.3 Details of the Method 15

3.4 Example 16

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4.1 Definitions 17

4.2 Summary 17


4.4 Example 18

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5.1 Definition 19

5.2 Summary 19


5.4 Example 20

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6.1 Definitions 21

6.2 Summary 21


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6.4 Example 21

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7.1 Definition 22

7.2 Summary 22


7.4 Lead Alkyl Equivalent 23

7.5 Example 24

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8.1 Definition 25

8.2 Summary 25


8.4 Example 26

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9.1 Definition 27

9.2 Summary 27


9.4 Example 28

9.5 Viscosity Conversion 28

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10.1 Definition 31

10.2 Summary 31


10.4 Example 32

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11.1 Definition 33

11.2 Summary 33


11.4 Example 34

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12.1 Definition 35

12.2 Summary 35


12.4 Example 36

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13.1 Definition 37

13.2 Summary 37


13.4 Example 37

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14.1 Definition 38

14.2 Summary 38


14.4 Example 39

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15.1 Definition 40

15.2 Summary 40


15.4 Example 41

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16.1 Definition 42

16.2 Summary 42


16.4 Examples 44

16.4.1 Distillates Blending 44

16.4.2 Fuel Oil Blending 44

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17.1 Definition 46

17.2 Summary 46


17.4 Example 47

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Methods are described for predicting the main properties of blended petroleum products fromthe knowledge of the properties of the blending components used.

There are methods for most of the bulk properties of gasolines, middle distillates and fuel oils.

The methods are primarily intended for use in linear programming matrices to produce refineryproduction estimates. They are all, therefore, basically linear or can be adapted, by means of ablending index, to be linear. This means that a component is assumed to blend in the same wayregardless of its proportion in the blend or of what other components are present.

In Section 2 estimation methods to calculate unknown blending’s component properties aregiven when available.

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API Technical Data Book, Petroleum Refining, 5th Edition, May 1992, 11th Revision Package

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Sheet 6 (47)


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When a property of a component of the blend is not known, we have to estimate it. There aremethods to estimate almost any property, but not all of them can provide accurate results.A selection of available estimation methods is given hereinafter.

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A petroleum fraction is formed by a huge number of individual pure compounds. It is notpractical and often not even possible to have a detailed composition of the petroleum cutexpressed in terms of pure components.

When the process engineer needs to know the value of a particular property, the onlyalternative to an analytical determination is the estimation of that property using empiricalcorrelations.Methods described in the following paragraphs are mainly from the API Technical Data Book.

There are some properties that are the key parameters to estimate other characteristics of thepetroleum fractions. They are listed herebelow in order of importance:

I. Specific Gravity 15.6°C/15.6°C

II. Mean Average Boiling Point (MeABP)

III. Molecular Weight

IV. Watson characterization factor (simply K or KUOP)

V. Two pairs viscosity / temperature points.

Provided that at least two of them are known, the process engineer can estimate, by means ofnomograph and/or equations, the other properties. The API Technical Data Book Fig. 2B6.1(which correlates: API Gravity, Mean Average Boiling Point, Molecular Weight, H/C Ratio,Aniline Point and K) is attached.

Equations to be used to calculate the properties are also included in the following pages, whenavailable.

2.1.1 Characterization Factor

The Watson characterization factor represent a satisfactory and widely used index forcorrelating the physical and thermal properties of straight-run petroleum fractions. It is anapproximate index of paraffinicity, with high values corresponding to high degrees of saturation.

It does not accurately characterize fractions containing appreciable quantity of olefinic oraromatic compounds (Catalytical Cracker Recycle Oils, Catalytical Reformer Streams, streamsfrom synthesis processes).

The characterization factor is defined and calculated according to the following equation:

K1.8 (MeABP 273.15)

SpGr

3

=⋅ +

where:

K = Watson characterization factor

SpGr = Specific Gravity 15.6°C/15.6°C.

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Sheet 7 (47)


� PRG.PT.GEN.0001


Sheet 8 (47)


MeABP = Mean Average Boiling Point in °C, defined as:

MeABPMABP CABP

=+2

where:

MABP is the Molal Average Boiling Point,

CABP is the Cubic Average Boiling Point.

In case that only the VABP (Volume Average Boiling Point) is available, the MeABP can becalculated using the following equation:

MeABP VABP exp= − − − ⋅ − + ⋅( . . ( ) . ).0 94402 0 00865 32 2 997910 6667 3VABP SL

where VABP is the Volumetric Average Boiling Point in °F, defined as:

VABPT T T T T

=+ + + +10 30 50 70 90

5

and SL is the 10-90 percent slope (ASTM D86) in °F, defined as:

SLT T

=−−

90 10

90 10

and the other terms are:

T10 = ASTM D86 temperature of the 10 vol.% distilled in °F





For pure components the MeABP is assumed equal to the Normal Boiling Point of thecomponent itself. When only 50% of the distillation curve is available the MeABP is assumedequal to the Mid Boiling Point or 50% Boiling Point of the petroleum cut.

2.1.2 Molecular Weight of Petroleum Fractions

The Molecular Weight (MW) of petroleum fractions can be estimated with the following equation(applicable in the following range of Molecular Weight: 70÷700 kg/kmol, MeABP: 90÷1050°Fand Specific Gravity: 0.63÷0.97):

( )MW T SpGr T SpGr T SpGrB B B= ⋅ ⋅ ⋅ − ⋅ + ⋅ ⋅ ⋅

⋅ ⋅− −20 486 1165 10 7 787125 11582 104 3 126007 4 98308. exp . . . . .

where:

TB = Mean Average Boiling Point of the petroleum fraction in °R


� PRG.PT.GEN.0001


Sheet 9 (47)


2.1.3 Molecular Weight of Heavy Petroleum Fractions

The Molecular Weight of heavy petroleum fractions (in the Molecular Weight range of 200 to800) can be estimated with the following equation:

MW SpGrSpGr SpGr= ⋅ ⋅ ⋅− + ⋅ − ⋅ −223 56 10012435 11228

2103 4758 3 038 0 6665. ( . . ) ( . . ) .ν ν

where:

ν100 = Kinematic Viscosity in cSt at 100°F



If the Specific Gravity is not available, the following equation could be used to estimate its value:

SpGr = ⋅ ⋅ −0 7717 1000 1157

2100 1616. . .ν ν

where:



2.1.4 Specific Gravity / Density

Specific Gravity or Density at reference conditions (usually 15.6°C) is the main property whencharacterizing a petroleum cut, and it is generally well known. If it has to be estimated, weshould know at least two of the following:

• Watson characterization factor,

• MeABP,

• Molecular Weight,

• Two pairs viscosity / temperature points.

Then simply utilize one of the above mentioned correlations/graphs to estimate the SpecificGravity of the petroleum cut.

2.1.5 Flowing Density

Density of a petroleum fraction at flowing conditions of temperature, when Specific Gravity isknown, can be estimated using the following equation:

( ) ( )d SpGr

SpGr MeABP T

MeABP= ⋅ −

⋅ − + ⋅ ⋅ ⋅ −−

0 99912655 0 5098 8 011 10 519 67

2

5

.. . . .

where:

d = density in kg/dm3 at flowing temperature


MeABP = Mean Average Boiling Point of the petroleum fraction in °R

T = Flowing temperature in °R

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Sheet 10 (47)


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According to API Procedure 14A1.3, the Gross Heat of Combustion of liquid fuels (i.e.: Fuel Oil,Heating Oil, etc.) can be calculated by the following equation:

( ) ( ) ( )− = + ⋅ − − ⋅ − − ⋅ −∗∆H 41105.1 154.9 A 131.5 0.735 A 131.5 0.00326 A 131.5gross2 3

where:

ASpGr

=⋅ +1179 8874

8 34516 0 0101578.

. .

If water, sulphur or inerts are present, Heat of Combustion must be corrected according to thefollowing equation:

( ) ( ) ( )− = − − ⋅ − ⋅ + + + ⋅∗ ∗∆ ∆ ∆H H H H O S Inerts Sgross gross gross e e e0 01 40 52. % % % . %

where:

%H2O = wt.% of water in the fuel

%Se = wt.% of sulphur in the fuel minus the average wt.%

%Inertse = wt.% of Inerts in the fuel minus the average wt.%

The average wt.% values as a function of the density of the oil are reported in the followingtable:

Density, kg/m3 Avg. Sulphur, wt.% Avg. Inerts, wt.% Avg. C/H Ratio

1.074 2.95 1.15 8.80

1.035 2.35 1.00 8.55

0.998 1.80 0.95 8.06

0.964 1.35 0.85 7.69

0.932 1.00 0.75 7.65

0.902 0.70 0.70 7.17

0.874 0.40 0.65 6.79

0.848 0.30 0.60 6.50

The Net Heat of Combustion can be calculated by the following equation:

( ) ( ) ( )− = + ⋅ − − ⋅ − − ⋅ −∗∆H A A Anet 39067 5 126 8 1315 0 505 1315 0 00442 13152 3

. . . . . . .

where:

Ad

=⋅ +

1179 88748 34516 0 0101578

.. .

If water, sulphur or inerts are present Heat of Combustion must be corrected according to thefollowing equation:

� PRG.PT.GEN.0001


Sheet 11 (47)


( ) ( ) ( ) ( )− = − − ⋅ − ⋅ + + + ⋅ − ⋅∗ ∗∆ ∆ ∆H H H H O S Inerts S H Onet net net e e e0 01 40 5 10 532 2. % % % . % . %

Example

Find the Gross Heating value of an oil with the following characteristics:

Density = 0.981kg/m3

S = 2.0 wt.%

H2O = 0.2 wt.%

Inerts = 0.8 wt.%

Procedure:

1. Calculate the Gross Heating value:

-∆Hgross = 411051 154 9 0 735 0 00326 42 9132 3. . . . /+ ⋅ − ⋅ − ⋅ =B B B kJ kg

where:

B =⋅ +

− =1179 88748 34516 0 981 0 0101578

1315 12 4456.

. . .. .

2. From Table 1 and by interpolation we get:

Average Sulphur = 1.575

Average Inerts = 0.900

Then calculate:

%Se = 2.0 - 1.575 = 0.425

%Inertse = 0.8 - 0.900 = -0.100

3. Calculate the Gross Heating Value Corrected

( ) ( ) ( )− = − ⋅ − ⋅ + − + ⋅∆Hgross 42913 0 01 42913 0 2 0 425 01 40 5 0 425. . . . . .

− =∆H kJ kggross 42670 /

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According to the API Procedure 2B7.1, the Flash Point (Pensky-Martens Closed Cup,ASTM D93) of petroleum fractions can be estimated using the following equation:

T

TT

FP =− + + ⋅ ⋅−

1

0 0145682 84947

1903 1010

310.

.. ln

where:

TFP = Flash Point of Petroleum Fraction in °R

T10R= ASTM 10% temperature for petroleum fractions or normal boiling point for purecomponents, in °R.

Flash Point can be predicted over the following range of Flash Points: -15÷325°F and ASTM10% or normal boiling points: 150÷1150°F.

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Sheet 12 (47)


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According to the ASTM Procedure 11A4.1, the liquid viscosity of petroleum fractions can beestimated when Specific Gravity and Watson characterization factor are known.Two equations for kinematic viscosity at 100°F and 210°F have been developed and arereported herebelow, by knowing the characterisation factor K and API gravity:

( )log . . . . .

. . . .. .

ν1002 4 2 2

2 2 2

4 3971 194733 012769 3 2629 10 118246 10

0171617 10 9943 9 50663 10 0 86021850 3642 4 78231

= − ⋅ + ⋅ + ⋅ ⋅ − ⋅ ⋅ ⋅

+⋅ + ⋅ + ⋅ ⋅ − ⋅ ⋅

+ − ⋅

− −

−

K K API K API

K API API K APIAPI K

( )log . . . .

. . .. .

ν2104 2 3

2 2

0 463634 0166532 513447 10 8 48995 10

8 03250 10 124899 01976826 786 2 6296

= − − ⋅ + ⋅ ⋅ − ⋅ ⋅ ⋅

+⋅ ⋅ + ⋅ + ⋅

+ − ⋅

− −

−

API API K API

K API APIAPI K

Similar results are quickly obtained by means of the API Technical Data BookChart 11A4.1 - “Liquid Viscosity of Petroleum Fractions at Atmospheric Pressure”. Enteringthe chart with KUOP and SpGr, the user can obtain the kinematic viscosity at 100°F and 210°F.

2.4.1 Viscosity at a different temperature

When blending viscosity all data to be blended must be referred to the same temperature.Quite often, kinematic viscosity is defined at two different temperature but may be none of thetwo is at the desired temperature. This is usually the case because the viscosity vary greatlywith temperature and viscosity figures at temperatures suitable for distillates may be unpracticalfor residual oils.

For example:

Vacuum Residue Kerosene

ν100°C = 550 cSt ν100°C = 0.76 cSt

ν50°C = 33400 cSt ν50°C = 1.20 cSt

ν20°C = 2000000 cSt ν20°C = 1.80 cSt

To estimate the viscosity when two pairs of viscosity/temperature points are known, it can bevery helpful one of the Charts “ASTM Standard Viscosity / Temperature chart” or “TemperatureVariation of Liquid Viscosity” .These chart have a scale that allows to draw the viscosity/temperature function as a straight linefor quick and easy interpolation or extrapolation.Simply put on the charts two pairs viscosity/temperature points and draw a line between them,then enter the chart with a temperature and read in correspondance of the line the viscosity atthat temperature.

To calculate viscosity at different temperature some approximate correlations (for more rigorousmethods refer to the ASTM D341) that can be applied are the followings:

( )[ ]Y1 1 0 7= +ln ln .ν

( )[ ]Y2 2 0 7= +ln ln .ν

� PRG.PT.GEN.0001


Sheet 13 (47)


( )X Tx X= +ln 460

( )X T1 1 460= +ln

( )X T2 2 460= +ln

( ) ( ) ( )[ ]Y X X Y Y X X YX X= − ⋅ − − +1 2 1 2 1 1/

νx = exp(exp(Yx) - 0.7)

where:

ν1 = kinematic viscosity at T1, °F

ν2 = kinematic viscosity at T2, °F

νX = kinematic viscosity at the desired temperature

Somethimes, only one point of viscosity at a temperature is known, but we need viscosity at adifferent temperature to be able to estimate the related properties.

a) If the component is a straight run petroleum cut and when the crude source is known orwhen the viscosity at more than one temperature of another cut that come from the samecrude source are known, then we can use the method described below:

I. Select the cut nearest to the one of interest

II. Draw on the ASTM Viscosity chart the line between the points with known viscosities

III. Mark on the chart the point of Viscosity for the cut with only one point of viscosity

IV. Draw on the chart a line passing through that single point and parallel to the linepreviously drawn

V. Then read on the chart viscosity at the desired temperature.

b) If the component is a heavy distillate (Gas Oil or heavier), the following equation permitsa rough but quick estimation of the the viscosity at 50°C, knowing the viscosity at 38°C:

ν ν50 383 33 0 367= + ⋅. .

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Aniline Point is a property used to estimate other properties like Cetane Number and DieselIndex by means of several correlations. The Aniline Point (in °F) is defined by the followingequation:

Aniline Point = ⋅100 DIAPI

where:

DI = Diesel Index

API = API Gravity

As an alternative Aniline Point can be estimated by means of the API Technical Data Booknomograph “Watson characterization factor of Petroleum Fraction”, included in para 2.2.1.

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Sheet 14 (47)


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The Cetane Number can be estimated with the following equation developed by HoustonRefinery based on 118 tests of random streams samples:

( )CN API MeABP AnilinePo= − + ⋅ + ⋅ + ⋅59 77 111 0 076 0 2. . . . int

where:

MeABP = Mean Average Boiling Point or Mid Boiling Point, °F

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According to API Procedure 2B8.1 the Pour Point of a petroleum fraction can be estimated asfollows:

( )T SpGr MWPPSpGr SpGr= ⋅ ⋅ ⋅− ⋅ − ⋅234 85 2 970566 0 61235 0 473575

1000 310311 0 32834. . . . ( . . )ν

where:

TPP = Pour Point of Petroleum Fraction in °R

ν100 = Kinematic viscosity in cSt at 100°F

MW = Molecular Weight of the Petroleum Fraction

SpGr = Specific Gravity 15.6/15.6°C.

The Pour Point can be predicted over the following range of Pour Points: -110÷140°F,Molecular Weight: 140÷800, Kinematic Viscosity: 1÷3500 and API gravity 1÷50.

For heavy petroleum cuts, when specific Pour Point data are not available, the “viscous PourPoint”, which is defined as the temperature at which the viscosity is 1,000,000 SUS, can beused instead.

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Sheet 15 (47)


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• The 6SHFLILF�*UDYLW\ is defined as the ratio of the weight of a given volume of material at15.6°C to the weight of an equal volume of distilled water at 15.6°C (60°F).

• The 'HQVLW\ or volumic mass is the mass of a substance per unit volume.Its numerical expression varies with the units selected, most often in kg/m3 or in lb/ft3.

There are some other methods to espress the density of a fluid that could be useful in theRefinery process calculation. In particular we mention:

• � $3,� *UDYLW\� RU� $3,� 'HJUHH; widely used to classify Crude Oil, and still used in theestimation of chemical and / or physical characteristics of petroleum products.

APISpGr

= −14151315

..

API Gravity will be often addressed in the following paragraphs, in particular when we needan estimate of a property.

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a) Specific Gravity and Density blend linearly on a volume basis.

b) Volume changes on blending are small and negligible for middle distillate blends.(When mixing light hydrocarbons with heavy hydrocarbons a contraction in the final volumeshould be expected. For example when mixing naphtha with heavy distillates, a contractionin the final volume as high as 0.1 per cent can be observed but it produces only a verysmall error of the predicted figure).

c) Linear blending of the Specific Gravities or Densities on a volume basis is mathematicallyexact.

d) It is essential that the components Densities which are to be blended should have beendetermined at the same temperature.If this is not the case then the Densities have to be converted to a common temperature,usually 15.6°C (60°F).

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The blend property is found by combining the property of the individual components in theirvolume proportion in the blend using the equation:

Pr( Pr )

opx op

xBi i

i=

⋅∑∑

where:

PropB = Specific Gravity or Density of the blend

xi = Volume percent of component i

Propi = Specific Gravity or Density of component i

� PRG.PT.GEN.0001


Sheet 16 (47)


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To illustrate the method, the following example shows how to calculate the Specific Gravity of ablend, when knowing the Specific Gravity of the individual components:

0DWHULDO 6S��*U��#��&��& 4XDQWLW\��YRO�� [L�⋅�6S*UL

Naphtha 0.775 7 5.43

Kerosene 0.800 15 12.00

LGO 0.835 78 65.13

Sum = 100 82.56

Blend Specific Gravity = 0.8256

� PRG.PT.GEN.0001


Sheet 17 (47)


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4.1.1 The 6XOSKXU� FRQWHQW is defined as the content of combined and/or free Sulphur of thepetroleum products expressed in terms of elemental Sulphur.

4.1.2 The 1LWURJHQ� FRQWHQW is defined as the content of combined and/or free Nitrogen of thepetroleum products expressed in terms of elemental Nitrogen.

4.1.3 The 0HUFDSWDQV�FRQWHQW is defined as the content in mercaptans of the petroleum products.

4.1.4 The &RQUDGVRQ�&DUERQ�5HVLGXH��&&5��content is the amount of carbon deposited after oil isburned.It indicates the relative carbon-forming tendency of petroleum products.

4.1.5 The 0HWDO�FRQWHQW (i.e.: Nickel, Vanadium, Iron, others) is defined as the content in metals ofthe petroleum products.

4.1.6 The +\GURFDUERQ�7\SH�FRQWHQW is defined as the content of a defined Hydrocarbon class type(i.e.: Paraffines, Olefines, Naphthenes, Aromatics content, Benzene content, etc.) of thepetroleum products.

4.1.7 The +HDW�RI�&RPEXVWLRQ of a substance is the heat evolved when that substance is converted(combustion) to its final oxidation products by means of molecular oxygen.

The 6WDQGDUG� +HDW� RI� &RPEXVWLRQ is defined as the Enthalpy change resulting from thecombustion of a substance starting and ending from a temperature of 25°C at atmosphericpressure.

The *URVV�+HDW�RI�&RPEXVWLRQ is similar to the Standard one, except that the combustionbegins and ends at 15.6°C rather than 25°C.

The difference between 6WDQGDUG and *URVV is only due to sensible heat of reactants andproducts between the two temperatures and it can be neglected in most cases.

The 1HW�+HDW�RI�&RPEXVWLRQ is the heat involved in a combustion beginning and ending at15.6°C with production of gaseous water and carbon dioxide

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a) The above mentioned properties blend linearly on a weight basis.

b) The method is theoretically justified, provided that the same test method to determine theproperty is used.


The blend property is found by combining the property of the individual components inproportion to the weight of each component present in the blend using the equation:

Pr( Pr )

opx op

xBi i

i

=⋅∑

∑

� PRG.PT.GEN.0001


Sheet 18 (47)


where:

PropB = Property of the blendxi = wt.% of component iPropi = Property of component i

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To illustrate the method, the following example shows how to calculate the Sulphur of a blend,knowing the Sulphur of the individual components:

0DWHULDO 6XOSKXU��ZW�� 4XDQWLW\��ZW�� [L�⋅�6L

Naphtha 0.01 6.6 0.066

Kerosene 0.26 14.5 3.770

LGO 1.40 78.9 110.460

Sum = 100.0 114.296

Blend Sulphur, wt% = 1.143

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Sheet 19 (47)


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The )ODVK�3RLQW is the lowest temperature at which a petroleum product vaporizes enough toform above its surface an air-vapour mixture which gives a flash or slight explosion whenignited by a small flame.The flash point of an oil is an indication of the risk of fire or explosion associated with itsusage, storage or handling.

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a) Flash Point does not blend linearly but a satisfactory index has been devised by Wickeyand Chittenden (Petroleum Refinery, Vol. 42, No. 6, June ‘63, pp. 157-158).

b) The index blends linearly on a volume basis. Wickey and Chittenden reported that theabsolute deviation of experimental and calculated values for 162 blends was 6°F.They noted that 71% of the deviations were within the reproducibility of the flash test ateach temperature level.

c) The blending index number may be used to blend flash temperatures determined in anyapparatus but, preferably, not to blend closed cup with open cup determinations.


a) Blending Index The Flash Point Blending Index is given by the relationship:

BIiFPi= +

−

10

4345 2

3836 1188

..

where:

FPi = Flash Point of the componenti, °F

b) Calculations The Flash Point of the blend is found by combining the Flash Point Blending Index of thecomponents in proportion to the volume of each component present in the blend usingthe equation:

FP

Logx BI

x

Bi i

i

=⋅

+

−∑

∑

4345 2

61188

383

10

.

(( )

) .

where:

FPB = Flash Point of the blend, °Fxi = volume percent of component iBIi = Flash Point Blending Index of component i

� PRG.PT.GEN.0001


Sheet 20 (47)


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To illustrate the method, the following example shows how to calculate the Flash Point of ablend, knowing the Flash Point of the individual components:

0DWHULDO )ODVK�3RLQW��& 4XDQWLW\�YRO�� &RPS��%�,� [L�⋅�)3L

Naphtha 35 7 936.6 6556.5

Kerosene 65 15 111.9 1678.7

LGO 100 78 15.3 1191.7

Sum = 100 9426.8

Blend Flash Point, °C = 67.7

� PRG.PT.GEN.0001


Sheet 21 (47)


�� 021��02725�0(7+2'�2&7$1(�180%(5

�� 'HILQLWLRQV

The 0RWRU�2FWDQH�1XPEHU of automotive gasolines is determined� by a test method whichindicates the knock characteristics under mild conditions, i.e. high temperature, high speedand/or high load. It is also known as the F-2 procedure.

�� 6XPPDU\

The above mentioned property blends linearly on a volume basis.


The blend property is found by combining the property of the individual components in theirvolume proportion in the blend using the equation:

M O Nx M O N

xBi i

i=

⋅∑∑

( )

where:

MONB = MON of the blend


MONi = MON of component i

�� ([DPSOH

To illustrate the method, the following example shows how to calculate the MON of a blend,when the Specific Gravity of the individual components is known.

0DWHULDO 021 4XDQWLW\��YRO�� [L�⋅�021L

S.R. Naphtha 60 15 900

Reformate 88 75 6600

HC Naphtha 62 10 620

Sum = 100 8120

Blend MON = 81.2

� PRG.PT.GEN.0001


Sheet 22 (47)


�� 521��5(6($5&+�0(7+2'�2&7$1(�180%(5��$670�'��

�� 'HILQLWLRQ

The 5HVHDUFK�0HWKRG�2FWDQH�1XPEHU��521� of automotive gasolines is determined by atest method which indicates the knock characteristics under mild conditions, i.e. temperatureand speed approximating ordinary driving conditions (also known as the F-1 procedure).Octane Number is usually expressed as “RON Clear” (without lead addition). When lead isadded to the stream, the Octane Number becomes higher and it is called “RON Leaded”.Lead is added to the gasoline as TML(Tetra-Methyl, Lead) or as TEL(Tetra-Ethyl, Lead).

�� 6XPPDU\

a) The RON does not blend linearly, but a satisfactory blending index system has beendevised.

b) The index blends linearly on a volume basis.

c) The method is not suitable for blends with alkylate or polymer, and there will be someloss in accuracy with blends with isomerates at intermediate lead levels.

d) The method is suitable for blends with TEL, TML and mixture of the two.

e) The only component data required are Clear Research ON's and the Sulphur contents ofany olefinic components if present.


a) Component GroupsThe components are divided into three groups, described as follows:

1. Olefinic components, i.e. Catalytically Cracked Gasolines, Steam Cracked Gasolinesand Thermal Reformates (Polymer may be included in this group but result shouldbe viewed with caution).

2. Aromatic Components, i.e. Reformates, Aromatic Concentrates, Aromatic Discardsand Motor Benzoles.

3. Straight Run Components, i.e. Straight Run Gasoline and Benzine, Isopentane andButane (Isomerates may be included in this group).

b) Blending IndicesThe blending indices for the various groups are given by the following equations:

• GROUP 1

BI R L L R L L S12 395 42743 0 83725 4189 0 6042 011308 2 301= + ⋅ + ⋅ − ⋅ − ⋅ ⋅ − ⋅ ⋅. . . . . .

where:

R = (RON - 95)

L = Weight of active lead added to blend (g/UKgal)

S = Wt.% of Sulphur in the component

� PRG.PT.GEN.0001


Sheet 23 (47)


• GROUP 2

BI R R R L

L R L R L L F R L F

R L F L F L F

22 3

2 2

2 2 2 2

95 42743 0 90183 0 002358 0 0003989 3 3614

0 54695 0 22196 0 03228 14679 0 30521

0 06744 2 3729 0 389

= + ⋅ − ⋅ − ⋅ + ⋅ −

⋅ − ⋅ ⋅ + ⋅ ⋅ + ⋅ ⋅ + ⋅ ⋅ ⋅ −

⋅ ⋅ ⋅ − ⋅ ⋅ + ⋅ ⋅

. . . . .

. . . . .

. . .

where:

F = Weight fraction of active lead as TML


R = (RON - 95)

• GROUP 3

BI R R L L R L33 2 278 6858 072079 0 00010314 6 925 10027 0 011183= + ⋅ − ⋅ + ⋅ − ⋅ − ⋅ ⋅. . . . . .

where:


R = (RON - 75)

c) CalculationsThe Research Octane No. of the blend is found by combining the RON Blending Index ofthe components in proportion to the volume of each component present in the blendusing the equation:

RON(x BI )

xBi i

i=

⋅∑∑

where:

RONB = Research Octane number of the blend


BIi = RON Blending Index of component i

�� /HDG�$ON\O�(TXLYDOHQW

1 ml of TEL = 1.057 grams Pb

1 ml of TML = 1.546 grams Pb

0.40 grams Pb/l = 1.817 g/UK gal

0.15 grams Pb/l = 0.681 g/UK gal

� PRG.PT.GEN.0001


Sheet 24 (47)


�� ([DPSOH

To illustrate the method, the following example shows how to calculate the RON of a blend,when the RON of the individual components is known.

0DWHULDO *URXS 521 4XDQWLW\�YRO�� &RPS��%�,� [L�⋅�%,L

S.R. Naphtha 3 67.0 15 72.972 1095

Reformate 2 101.0 75 100.67 7550

HC Naphtha 3 69.0 10 74.383 744

Sum = 100 9389

Blend RON = 93.9

� PRG.PT.GEN.0001


Sheet 25 (47)


�� 5(,'�9$3285�35(6685(�$670�'��

�� 'HILQLWLRQ

The Reid Vapour Pressure (RVP) is defined as the vapour pressure of volatile material undercontrolled conditions (100°F).

�� 6XPPDU\

Reid Vapour Pressure (RVP) should theoretically be blended on a molal basis. However it isvery difficult to estimate molecular weights of blend components accurately. In addition apurely molal blending method is inconvenient for use in linear programming.A convenient method has been developed on a simple volumetric basis.


a) Blending IndexThe RVP Blending Index is given by the following equation:

( )BI RVPi = 125.

where:

RVP = Reid Vapour Pressure, psia

b) CalculationsThe RVP of the blend is found by combining the RVP Blending Index of the components inproportion to the volume of each component present in the blend using the equation:

RVPBI

Bi

=⋅

∑∑(x )

x

i

i

0 8.

where:

RVPB = RVP of the blend, psia


Bii = RVP Blending Index of component i

� PRG.PT.GEN.0001


Sheet 26 (47)


�� ([DPSOH

0DWHULDO 593SVLD

4XDQWLW\YRO��

593%OHQGLQJ�,QGH[

[L�⋅�%,L

Stab. Light Naphtha 10 20 17.78 355.6

HC Naphtha 8 10 13.45 134.5

Reformate 3 70 3.95 276.5

Sum = 100 766.6

Blend RVP 5.1

� PRG.PT.GEN.0001


Sheet 27 (47)


�� 9,6&26,7<��$//�0(7+2'6�

�� 'HILQLWLRQ

The 9LVFRVLW\�is the measure of the internal friction or resistance to flow of a fluid.Viscosity is usually defined as '\QDPLF or .LQHPDWLF.The relation between Dynamic and Kinematic Viscosity is the following:

νµρ

=

In SI units kinematic viscosity is expressed in mm/s2 (same as centiStokes - cSt), whilstabsolute viscosity in mPa⋅s (same as centiPoise - cP).Viscosity, unlike other product properties is measured at various temperatures, 100°F, 122°F,140°F, and 210°F being particularly common.If viscosity data are known at two different temperatures, the viscosity can be found at anyother temperature by interpolation or extrapolation. The methods is described at paragraph2.4.1.It is most important that component viscosities are all brought back to the same temperaturebefore an attempt is made to calculate the blend viscosity.

�� 6XPPDU\

a) Kinematic viscosity measured in the usual units does not blend linearly but a satisfactoryblending index, known as the Refutas function, has been devised.

b) The index should be blended on a weight basis.

c) Care should be taken to ensure that all component viscosities are available at the sametemperature.


a) Blending IndexThe blending index or Refutas function is given by the relationship:

BI = + ⋅ ⋅ ⋅ +23 097 33 468 0 8. . log log ( . )ν

where:υ = Viscosity in centistokes

b) CalculationsThe Viscosity of the blend is found by combining the Viscosity Blending Index of thecomponents in proportion to the weight of each component present in the blend usingthe equation:

ν = −

⋅∑

∑−

10 0 810

23 097

33 468

xi Bi

xi.

..

where:ViscB = Viscosity of the blend, cSt

� PRG.PT.GEN.0001


Sheet 28 (47)


xi = Wt.% of component iBIi = Viscosity Blending Index of component i

c) Visbreaker Tar Blending IndexWhen blending Visbreaker Tar with any diluents, practice showed that the abovecorrelations were not applicable. The following equation, obtained from plant data,should be applied:

[ ]BI BI W WTF F F T T= + ⋅ ⋅ + ⋅ + ⋅ ⋅ + ⋅4 3055 0 0124 0 0087576 23 097 33 468 0 8. . . . . log log( . )υ

where:

BITF = Blending Index of the mix VB-Tar/Diluent at 50 or 100°C

BIF = Blending Index of the Diluent at 50 or 100°C

WF = Weight % of Diluent in the Mix

υT = Viscosity of VB-Tar in cSt at 50 or 100°C

WT = Weight % of VB-Tar in the Mix

Then calculate the Viscosity of the mix using the following:

νTF

BI

= −

−

10 0 810

23 097

33 468

.

..

where:νTF = Viscosity of the mix VB-Tar/Diluent in cSt at 50 or 100°C

�� ([DPSOH

0DWHULDO 9LVFRVLW\#��&

4XDQWLW\�YRO��

9LVFRVLW\%�,�

[L�⋅�%,L

Atm. Residue 380 60 36.877 2212.6

Vac. Residue 52000 25 45.640 1141.0

HAGO 4.6 15 18.570 278.6

Sum = 100 3632.2

Blend Viscosity 304

�� 9LVFRVLW\�&RQYHUVLRQ

9.5.1 Viscosity data available in different units

The more used are:

• Engler degrees, °E

• Saybolt Universal Seconds, SUS

• Saybolt Furol Seconds, SFS

• Redwood No.1 (Standard), RW1

� PRG.PT.GEN.0001


Sheet 29 (47)


• Redwood No.2 (Admiralty), RW2

Some methods useful for a quick but approximate conversion are reported hereinafter.

9.5.2 Conversion of Kinematic Viscosity to SUS

The Saybolt Universal viscosities at 100°F may be calculated by equation

( )( )[ ]SUSeq = +

+

+ ⋅ + ⋅ + ⋅ ⋅ −4 6324

10 0 03264

3930 2 2627 23 97 1646 101

1

1 12

13 5

.. .

. . . .υ

υ

υ υ υ

and those at a temperature W by equation

( )[ ]SUS t SUSt eq= + ⋅ − ⋅1 0 000061 100.

Alternatively, the conversion from Saybolt Universal Seconds can be made using the followingequation:

For SUS ≤ 49.01

ν = − + ⋅ +9 383303 0 32787820 941

. ..

SUSSUS

For 49.01 < SUS ≤ 70.00

ν = ⋅ −0 22180

. SUSSUS

For SUS > 70.00

ν = SUS4 635.

9.5.3 Conversion of kinematic viscosity to Saybolt Furol Seconds

For computer use, the conversion of kinematic viscosity to Saybolt Furol viscosity may be madeusing the following equations, which are valid above 1300 cSt as well as below 1300 cSt

SFS FF F

F1221222

122

0 471713 924

72 59 6816122°° °

= +− +°

..

.υ υ

SFS FF

F2102102

0 47925610

2130210°°

= ++°

. υ υ

Alternatively the conversion from SFS can be made using the following equation

For SFS ≤ 188.8

ν = − + ⋅ −0 15436 21238016147 689

. ..

SFSSFS

For SFS > 188.8

� PRG.PT.GEN.0001


Sheet 30 (47)


ν = SFS0 4717.

9.5.4 Conversion of Kinematic Viscosity to RW1, RW2 and °E

The conversion of kinematic viscosity to Redwood No. 1 viscosity at 140 F to Redwood No. 2viscosity, and to Engler viscosity can be made using the equation:

T AB C D E

= ⋅ −+ ⋅ + ⋅ + ⋅

νν ν ν

12 2

Alternatively, the conversion of Redwood No. 1 viscosity at 140°F, Redwood No. 2 viscosity,and Engler viscosity to kinematic viscosity can be made using the equation:

ν = −+

FTGT

T H3

where:

T = Flow time, in seconds or Engler degrees

υ = kinematic viscosity, in cSt

A÷H = constants given in the following Table:

&RQVWDQW)URP�F6W

WR�5:��DW��)

)URP�F67

WR�5:�

)URP�F6W

WR��(

A 4.0984 0.40984 0.13158

B 0.038014 0.38014 1.1326

C 0.001919 0.01919 0.01040

D 0.0000278 0.000278 0.00656

E 0.00000521 0.0000521 0.0

Range of υ >4.0 >73 >1.0

&RQVWDQW)URP�5:��DW��)

WR�F6W

)URP�5:�

WR�F67

)URP��(

WR�F6W

F 0.244 2.44 7.60

G 8000 3410 18

H 12500 9550 1.7273

Range of T >35 >31 >1.000

This procedure, however, is not recommended in as much as the conversion of empiricalviscosities to kinematic may be subject to large errors. The accuracy of the Redwood and theEngler instruments does not usually justify such a procedure.

� PRG.PT.GEN.0001


Sheet 31 (47)


�� &2/285�$670�'��

�� 'HILQLWLRQ

&RORXU� is measured for undyed commercial petroleum products, Colour ranging fromcolourless to opaque.It is determined by matching the transmitted light from an oil sample with specified standards.

�� 6XPPDU\

a) Colour does not blend linearly but a satisfactory index system has been devised.



a) Blending IndexThe blending index is tabulated and shown in the following table at 0.1 intervals of thecolour scale.

�� 0.00 0.13 0.26 0.39 0.52 0.65 0.75 0.84 0.94 1.04�� 1.13 1.25 1.37 1.49 1.61 1.74 1.91 2.08 2.25 2.42�� 2.59 2.78 2.98 3.17 3.37 3.56 3.86 4.17 4.47 4.78�� 5.08 5.38 5.68 5.97 6.27 6.57 6.89 7.21 7.53 7.85�� 8.17 8.46 8.75 9.04 9.33 9.62 9.88 10.13 10.39 10.65�� 10.91 11.20 11.49 11.78 12.07 12.36 12.70 13.04 13.39 13.73�� 14.07 14.43 14.78 15.13 15.49 15.84 16.26 16.69 17.11 17.53�� 17.95 18.54 19.13 19.72 20.31 20.90 21.93 22.95 23.97 24.99�� 26.02 27.04 28.06 29.08 30.11 31.13 32.15 33.17 34.20 35.22

b) CalculationsThe ASTM Colour index of the blend is found by combining the Colour Blending Index ofthe components in proportion to the volume of each component present in the blend usingthe equation:

BIBI

Blend =⋅∑

∑(x )

x

i i

i

where:

BIBlend= Blend Colour Blending Index


BIi = Colour Blending Index of component i

c) ASTM Colour of the BlendThe estimated ASTM Colour of the blend is then obtained by entering the table inverselywith the calculated Blend Colour Blending Index.

� PRG.PT.GEN.0001


Sheet 32 (47)


�� ([DPSOH

0DWHULDO &RORXU 4XDQWLW\�YRO��

&RORXU��%�,� [L�⋅�%,L

S.R. LAGO 3.5 70 6.57 459.9

S.R. Kerosene 1.0 15 1.13 17.0

S.R. LVGO 7.0 15 17.95 269.2

Sum = 100 746.1

Blend Colour 3.8

� PRG.PT.GEN.0001


Sheet 33 (47)


�� 602.(�32,17��$670�'��$1'�/80,120(7(5�180%(5

�� 'HILQLWLRQ

The 6PRNH�3RLQW is defined as the highest smoke-free flame which can be obtained with akerosene under specified conditions in a standard lamp.It is, therefore, a performance test which gives an indication of the maximum light emission ormaximum heat generation that can be obtained from a kerosene, when burnt without smokingin appliances.The /XPLQRPHWHU�1XPEHU is a measure of flame temperature at a fixed flame radiation andit is related to the characteristics of Jet fuels used in aviation turbine engines.

�� 6XPPDU\

a) When blending components with different Smoke Points, the Smoke Point of the blendcannot be predicted by linear calculation.

b) A method is being proposed to calculate the Smoke Point of a blend from the volumeconcentrations and Smoke Points of the components.

c) The two properties are strictly related and, based on empirical observations, arelationship between the two values was developed.The equation is the following:

LN SP= ⋅ −172 105(log . )


a) Blending IndexThe Smoke Point Blending Index is given by the following equation:

BISPi

i

= 100

where:SPi is the Smoke Point of component i.

b) CalculationsThe Smoke Point of the blend is found by combining the Smoke Point Blending Index ofthe components in proportion to the volume of each component present in the blendusing the equation:

SPBI

Bi

= ⋅⋅∑

∑100

(x )

x

i

i

where:SPB = Smoke Point of the blendxi = Volume percent of component iBIi = Smoke Point Blending Index of component i

� PRG.PT.GEN.0001


Sheet 34 (47)


�� ([DPSOH

0DWHULDO 6PRNH3RLQW

4XDQWLW\YRO��

6PRNH�3RLQW%OHQGLQJ�,QGH[

[L�⋅�%,L

SR Kerosene 24.0 55 4.167 229.18

HC Kerosene 26.0 30 3.846 115.38

HDS Kerosene 25.0 15 4.000 60.00

Sum = 100 404.60

Blend Smoke Point 24.70

� PRG.PT.GEN.0001


Sheet 35 (47)


�� $1,/,1(�32,17�$670�'��

�� 'HILQLWLRQ

The $QLOLQH�3RLQW is the minimum temperature at which equal volumes of dry, freshly distilledAniline and the petroleum products are completely miscible.The Aniline Point is a measure of the degree of molecular condensation of the oil.It is a simple and precise test and a good indicator of the hydrocarbon type of the oil.It is also useful to estimate the Cetane Number and Diesel index.

�� 6XPPDU\

a) For straight run materials Aniline Point blends linearly on a weight basis.

b) For blends of straight run and catalytically cracked materials an "Aniline blending number"should be used for the catalytically cracked materials only, if their Aniline Point is lowerthan 40°C.


a) Blending IndexCatalytically cracked materials when mixed with straight run products blend with a "higherthan determined" Aniline Point if the Aniline Point is lower than 40°C. This higher value istermed here the Aniline Blending Number.Aniline Blending Number. is calculated as follows:

ABN APIi = + ⋅211 0 4125. .

where:

API = API Gravity

b) CalculationsThe Aniline Point of the blend is found by combining the Aniline Point or Aniline BlendingNumber of the components in proportion to the weight of each component present in theblend using the equation:

APA

B =⋅∑

∑(x BN )

x

i i

i

where:

APB = Aniline Point of the blend

xi = Weight fraction of component i

ABNi = Aniline Point or Aniline Blending Number of component i

� PRG.PT.GEN.0001


Sheet 36 (47)


�� ([DPSOH

0DWHULDO $QLOLQH3RLQW

4XDQWLW\YRO��

$QLOLQH�%OHQGLQJ1XPEHU

[L�⋅�%LL

S.R. LAGO 67.8 30 67.8 20.34

S.R. HAGO 76.0 55 76.0 41.80

S.R. LVGO 71.0 15 71.0 10.65

Sum = 100 72.79

Blend Aniline Point 72.80

� PRG.PT.GEN.0001


Sheet 37 (47)


�� ',(6(/�,1'(;�,3��

�� 'HILQLWLRQ

The Diesel Index of a gas oil is a measure of its ignition quality.The Diesel Index is the product of Aniline Point in °F and the API gravity divided by 100.

DIAPI AnilinePo= ⋅ int

100

�� 6XPPDU\

a) Diesel Index blends linearly on a weight basis.

b) Diesel Index can be calculated from Specific Gravity 15.6°C/15.6°C and Aniline Point.


The Diesel Index of a blend is found by combining the Diesel Indices of the components inproportion to the weight of each component present in the blend using the equation:

DIBI

Bi

=⋅∑

∑(x )

x

i

i

where:

DIB = Diesel Index of the blend

xi = Wt.% of component i

BIi = Diesel Index of component i

�� ([DPSOH

0DWHULDO 4XDQWLW\�YRO�� 'LHVHO�,QGH[ [L�⋅�%,L

S.R. LAGO 30 58 1740

S.R. HAGO 55 49 2695

S.R. LVGO 15 45 675

Sum = 100 5110

Blend Diesel Index 51

� PRG.PT.GEN.0001


Sheet 38 (47)


�� &(7$1(�180%(5��$670�'��$1'�&(7$1(�,1'(;��$670�'��,3��

�� 'HILQLWLRQ

The &HWDQH�1XPEHU�expresses the ignition quality of a diesel fuel by the delay in combustionafter injection of the fuel and it is evaluated in a test engine (ASTM D613).Since this method requires special equipment and determination is costly and timeconsuming, some methods for prediction of Cetane have been developed.When Cetane is not evaluated but predicted according to the ASTM Method D976/IP218 it isdefined as “Cetane Index”.Cetane Index according to the ASTM is defined by the following equation:

( )[ ]CI d d MBC MBC= − ⋅ + ⋅ − ⋅ + ⋅454 74 1641416 774 74 0 554 97 8032 2. . . . . log

where:

CI = Cetane Index

MBC= Mean Average Boiling Point or Mid Boiling Point in °C

d = Density at 15°C

Alternatively the Cetane Index can be obtained by means of a chart available in the ASTMMethod itself.

�� 6XPPDU\

a) The Cetane Number does not blend linearly but a satisfactory index has been devised.



a) Blending IndexThe Cetane Number Blending Index is given by the relationship:

BI CN CNi i i= + ⋅ + ⋅5 28 0 371 0 0112 2. . .

where:

CNi = Cetane Number of component i

b) CalculationsThe Cetane Number of the blend is found by combining the Cetane Number Blending Indexof the components in proportion to the volume of each component present in the blendusing the following equations:

BIBI

Bi

=⋅∑

∑(x )

x

i

i

CN BI BIB B B= + ⋅ − ⋅4 3 107657 0 00374 2. . .

where:

BIB = volume average Blending Index of the blend

xi = volume percent of component i

CNB = Cetane Number of the blend

� PRG.PT.GEN.0001


Sheet 39 (47)


�� ([DPSOH

0DWHULDO &HWDQH1XPEHU

4XDQWLW\YRO��

&HWDQH�1XPEHU%OHQGLQJ�,QGH[

[L�⋅�%,L

HDS Light Gas Oil 51 45 53.3 24.0

HDS Heavy Gas Oil 53 30 56.4 16.9

HC Gas Oil 54 25 58.0 14.5

Sum = 100 55.4

Blend Cetane Number 52.5

� PRG.PT.GEN.0001


Sheet 40 (47)


�� )5((=,1*�32,17

�� 'HILQLWLRQ

The )UHH]LQJ�3RLQW is defined as the lowest temperature at which a fluid will freeze whenchilled without disturbance under specified conditions.

�� 6XPPDU\

a) Freezing Point does not blend linearly but a satisfactory index system has been devised.

b) The index blends linearly on a weight basis.


a) Blending IndexThe blending index is given by the relationship:

if Freezing Point ≤ 0°C:

( )BIiFRPi= ⋅ +10 0 010332 15506. .

if Freezing Point > 0°C:

( )BIiFRPi= ⋅ +10 0 016644 15554. .

where:

FRPi = Freezing point of component i, °C

b) CalculationsThe Freezing Point of a blend is found by first combining the Blending Indices of thecomponents in proportion to the weight of each component present in the blend using theequation:

BIBI

Bi

=⋅∑

∑(x )

x

i

i

where:

BIB = Freezing point of the blend, °C

Then, if FRPB ≤ 35.78:

FRPBI

BB= −log( ) .

.15506

0 010332

otherwise:

FRPBI

BB= −log( ) .

.15554

0 016644

� PRG.PT.GEN.0001


Sheet 41 (47)


�� ([DPSOH

0DWHULDO )UHH]LQJ3RLQW

4XDQWLW\ZW��

)UHH]LQJ�3RLQW%OHQGLQJ�,QGH[

[L�⋅�%,L

HDS Kerosene -51 50 10.73 5.36

HC Kerosene -55 35 9.77 3.42

SR Kerosene -45 15 12.35 1.85

Sum = 100 10.63

Blend Freezing Point -51.00

� PRG.PT.GEN.0001


Sheet 42 (47)


�� 3285�32,17�$670�'��

�� 'HILQLWLRQ

The 3RXU�3RLQW is defined as the lowest temperature at which a fluid will pour when chilledwithout disturbance under specified conditions.

�� 6XPPDU\

a) Pour Point does not blend linearly but an index system has been devised for middledistillates and fuel oils.

b) The index blends linearly on a weight basis.


Two different methods are to be used when blending atmospheric distillates and fuel oil.

a) Atmospheric DistillatesThe blending index is given by the following equation:

(log . )BI PPi i= ⋅ +0 0105 100

where:

PPi = Pour Point in °F of the component i

For hydrocracked Gas Oils add 4.2 to the index obtained from the above equation.

b) Fuel OilsDifferent blending indexes shall be used according to the kind of component.

I) Group 1 - DiluentsThe blending index for Kerosene, Atmospheric Gas Oil and Cracked Gas Oils iscalculated using the following equation:

(log(log ) . )BI PPi i= ⋅ +0 0021 100

where:


II) Group 2 - Atmospheric ResiduesThe blending index is:

BI PPiPP

ii= + + ⋅− + ⋅10 120 0 81157 0 034( . . ) .

where:


III) Group 3 - Vacuum Distillates When necessary to estimate a Blending Index of a Vacuum Distillate, it should be

calculated by weighted deblending the Vacuum Residue from the correspondingAtmospheric Residue.

� PRG.PT.GEN.0001


Sheet 43 (47)


IV) Group 4 - Vacuum ResiduesA rough estimate of the Blending Index for a Vacuum Residue can be calculated withthe following equation:

BI Si i= − ⋅ +278 72 0 93 0 4( . ) .

where:

Si = Sulphur wt.% of the component i

Better results can be obtained using empirical Blending Index. A selection of Indicesis reported in the following table:

&UXGH�7\SH &XW�3RLQW ,QGH[

Gach Saran 525 165Gach Saran 550 143Umm Shaif 525 155Umm Shaif 550 133Kuwait 525 130Kuwait 550 125Kirkuk 525 150Kirkuk 550 138Kirkuk 575 126Agha Jari 515 149Agha Jari 530 130Qatar 543 132Tia Juana 525 154Murban 525 184Murban 540 198Zeiten 525 227Zarzaitine 525 170Hassi Messaoud 510 158Jambur/Bai Hassan 525 133Libyan (Sarir) 500 270Libyan (Sarir) 550 240Libyan (Sarir) 590 225Nigerian (Light) 525 200Nigerian (Medium) 525 200Nigerian (Bonny) 525 200Nigerian (Light) 550 180Nigerian (Medium) 550 180Nigerian (Bonny) 550 180Zakum 525 175Zakum 550 165

� PRG.PT.GEN.0001


Sheet 44 (47)


b) CalculationsThe Pour Point Blending Index of the blend is found by combining the Pour PointBlending Index of the components in proportion to the weight of each component presentin the blend using the equation:

BIx BI

xBi i

i=

⋅∑∑( )

where:

BIB = Blending Index of the blend

xi = Weight percent of component i

BIi = Pour Point Blending Index of componenti

Then Pour Point of the blend can be calculated by substitution of the Blending index inthe equation given for the Atmospheric Residue.

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16.4.1 Distillates Blending

The following example shows how to calculate the Pour Point of a blend, when the Pour Point ofthe individual components is known.

0DWHULDO 3RXU�3RLQW��& 4XDQWLW\��ZW�� 3RXU�3RLQW�%�,� [L�⋅�%,L

LAGO -12 35 50.75 17.76

HDS Gas Oil 1 25 81.24 20.31

Atm Residue 30 40 287.1 114.8

Sum = 100 152.9

Blend Pour Point, °C = 16.4

16.4.2 Fuel Oil Blending

To illustrate the method, the following example shows how to calculate the Pour Point of ablend, when the Pour Point of the individual component is known.

For Light Atmospheric Gas Oil and HDS Gas Oil equation for group 1 will be used.For the Vacuum residue, the Blending Index value was taken from the table relevant to theVacuum Residues.The Blending Index for the Vacuum Gas Oil was calculated as follows:

Input Data:

• PPAtmRes ; Pour Point of the 350+ Sarir Atmospheric Residue = 46°C (114.8°F)

• PPVacRes ; Pour Point of the 550+ Sarir Vacuum Residue = 48°C (118.4°F)

• YVacRes ; Yield on Crude of the 550+ Sarir Vacuum Residue = 22.80 wt.%

• YVacGas Oil ; Yield on Crude of the 350-550 Sarir Vacuum Gas Oil = 27.45 wt.%

� PRG.PT.GEN.0001


Sheet 45 (47)


Step-by-step procedure:

I. Calculate the weight fractions of Vacuum Gas Oil and Vacuum Residue as follows:

XY

Y YVacGasoilVacGasoil

VacGasoil Vac sidue

=+ Re

X XVac sidue VacGasoilRe = −1

X VacGasoil =+

=27 4527 45 22 80

0 546.

. ..

XVac sidueRe . .= − =1 0 546 0 454

II. Calculate the Blending Index of Atmospheric Residue using the equation for group 2:

BIAtm sidueRe( . . . ) . . .= + + ⋅ =− + ⋅10 120 0 81 114 8 428 4157 0 034 114 8

III. Obtain the Blending Index of the 550+ Vacuum Residue from table for group 3:

BIVac sidueRe = 240

IV. Then considering the Atmospheric Residue as the blend formed by all the Vacuum Gas Oil

plus the Vacuum Residue and by Substitution in the Blending Equation (point B of thepreceeding paragraph), we obtain:

BIX BI X BI

X XAtm sVacGasoil VacGasoil Vac sidue Vac sidue

VacGasoil Vac sidueRe

Re Re

Re

=⋅ + ⋅

+

BIBI X X X BI

XVacGasoilAtm s VacGasoil Vac sidue Vac sidue Vac sidue

VacGasoil

=⋅ + − ⋅Re Re Re Re( )

BIVacGasoil = ⋅ − ⋅ =428 4 1 0 454 2400 546

5851. .

..

0DWHULDO *URXS3RXU

3RLQW��&4XDQWLW\ZW��

3RXU�3RLQW%�,� [L�⋅�%,L

Light Atmospheric Gas Oil 1 -12 35 50.75 1776

HDS Gas Oil 1 +1 25 81.24 2031

Sarir 350-550 Vacuum GasOil

3 +45 25 585.1 14627

Sarir 550+ Vacuum Residue 4 +48 15 240.0 3600

Sum = 100 22032

Blend Pour Point, °C = 31.6

� PRG.PT.GEN.0001


Sheet 46 (47)


�� &/28'�32,17�$670�'��

�� 'HILQLWLRQ

The &ORXG� 3RLQW is defined as the temperature at which paraffines, waxes or othercomponents begin to crystallize out or separate from solution when the oil-stream is chilledunder specified conditions.

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a) Cloud Point does not blend linearly but a satisfactory index system has been devised.



a) Blending IndexThe blending index is given by the following equation:

( )( )BIICP= ⋅ +

100 03366 73 3. .

where:

CP = Cloud Point in °C

b) CalculationsThe Cloud Point of the blend is found by combining the Cloud Point Blending Index of thecomponents in proportion to the volume of each component present in the blend usingthe equation:

CP

Log

B =

⋅

−

∑∑10

0 0336673 3

(x BI )

x

i i

i

..

where:

CPB = Cloud Point of the blend, °C


BIi = Cloud Point Blending Index of component i

� PRG.PT.GEN.0001


Sheet 47 (47)


�� ([DPSOH

0DWHULDO &ORXG3RLQW

4XDQWLW\�YRO��

&RPS��%�,� [L�⋅�%,L

HAGO 8.0 60 545.2 37210.0

LVGO 10.0 25 636.6 15920.0

HC Gas Oil -20.0 15 62.2 930.0

Sum = 100 54060.0

Blend Cloud Point 7.9

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