fundamentals of petroleum refining physical property...

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Fundamentals of Petroleum Refining

Physical Property Characterization data

Lecturers:

assistant teachers

Kirgina Maria Vladimirovna

Belinskaya Natalia Sergeevna

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Название темы

Fundamentals of Petroleum Refining. Physical Property Characterization data

Fractionation

Distillation of crude oils determines the yield of the products that

can be obtained from this crude oil when it is

processed in a refinery.

A light crude oil will

produce higher amounts

of gasoline

than a heavier

crude oil.

Different standard

distillation tests

can be performed

on crude oil or

petroleum fractions.

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True Boiling Point Distillation is boiling point versus volume or mass

percent distilled

is obtained through a batch

distillation test ASTM 2895

The distillation apparatus has 15-18

theoretical plates with 5:1 reflux ratio

For boiling points below 340 ºC the

distillation is performed at atmospheric

pressure

The residue is distilled under vacuum

This test allows for the collection of sample cuts at different boiling point

ranges.

These cuts can be subjected to physical and chemical measurements.

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Simulated Distillation by Gas Chromatography

The boiling point distribution of the whole crude oil can be determined

by an injection of the sample in a gas chromatograph which separates

the hydrocarbons in boiling point order

The retention time is related to the boiling point through a calibration

curve

The boiling point distribution

of light and heavy petroleum

cuts can also be done by

gas chromatography

One of the standards methods

of measurements

is ASTM D5307

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API Gravity

API gravity:

141.5131.5API

SGwhere SG is specific gravity defined as the density of the crude oil relative

to the density of water at 15.6 ºC.

The API gravity can range from 8.5 for very heavy crudes to 44 for light

crudes.

Classification of crude oil according to the gravity

Crude category Gravity

Light crudes API > 38

Medium crudes 38 < API < 29

Heavy crudes 29 > API > 8.5

Very heavy crudes API < 8.5

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Pour Point

is the lowest temperature at which the sample will flow

indicates

1) how easy or difficult it is to pump the oil, especially in cold weather

2) the aromaticity or the paraffinity of the crude oil or the fraction

A lower pour point means that the paraffin content is low

Pour points for the whole crude

and fractions boiling above 232 ºC

is determined by standard test like

ASTM D97

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Viscosity

The resistant to flow or the pumpability of the crude oil or petroleum

fraction is indicated by the viscosity

More viscous oils create a greater pressure drop

when they flow in pipes

Viscosity measurements is expressed in terms

of kinematic viscosity

Kinematic viscosity is measured

at 37.8 ºC by ASTM D445

and by ASTM D446 at 99 ºC

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Refractive Index

is the ratio of the velocity of light in a vacuum to the velocity of light in

the oil

This parameter used as a characterization parameter for petroleum

fraction composition

is measured according to ASTM D1218

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Freezing Point

heavy oils contain heavy compounds such as waxes or asphaltenes,

which tend to solidify at low temperatures, thus restricting flow

The freezing point is the temperature at which the hydrocarbon liquid

solidifies at atmospheric pressure

It is important property specification for kerosene and jet fuels due to

very low temperatures encountered at high attitudes in jet planes

One of the standard test is ASTM D4790 and ASTM D16

Solidification of diesel fuel in a

fuel-filtering device after sudden

temperature drop

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Aniline Point

is the lowest temperature at which an equal volume mixture of the

petroleum and aniline are miscible

Since aniline is an aromatic compound,

a petroleum fractions with high aromatic

content will be miscible in aniline

at ambient conditions

If oil has more paraffins, it will require

a higher temperature and thus higher

aniline point in order to miscible aniline

This property is important for

the specification of diesel fuels

Aniline point is measured by ASTM D611

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Flash Point

is the lowest temperature at which sufficient vapours are produced above the

liquid such that spontaneous ignition will occur if spark is present

Is important specification

for gasoline and

naphtha related to

safety in storage

and transport

in high-temperature

environment

Flash point indicates

the fire and explosion

potential of a fuel

A low flash point fuel is

a higher fire hazard

One of the standard test is ASTM D1711, D09 or D1695

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Octane Number

Is a measure of the knocking tendency of gasoline fuels in spark ignition engines.

The ability of fuel to resist auto-ignition during compression and prior to spark

ignition gives it a high octane number.

The octane number of a fuel is determined by measuring its knocking value

compared to the knocking of a mixture of n-heptane and isooctane.

n-heptane ON = 0

isooctane ON = 100 The motor octane number (MON)

indicates engine performance at high-way

conditions with high speed.

The research octane number (RON) is

indicative of low-speed city driving.

The posted octane number (PON) / Anti-

knock index (AKI) is the arithmetic

average of MON and RON.

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Cetane Number

measures the ability for auto ignition and is essentially the opposite of the octane

number.

is the percentage of pure cetane (n-hexadecane) in a blend of cetane and alpha

methyl naphthalene which matches the ignition quality of a diesel fuel sample.

This quality is specified for middle distillate fuels.

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Smoke Point

The smoke point is a test measures the burning qualities

of kerosene and jet fuel.

It is defined as the maximum height in mm, of a smokeless

flame of fuel.

Reid Vapour pressure

The reid vapour pressure (RVP) of a product is the vapour pressure determined

in a volume of air four times the liquid volume at 37.8 ºC.

RVP measures the vapour-lock

tendency of a motor gasoline in

which excessive vapours are produced

in the fuel line causing interruption of

the supply of liquid fuel to the engine.

RVP also indicates the explosion

and evaporation hazards of the fuel.

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Water, Salt and Sediment

Chlorides of magnesium, calcium and sodium are the most common salts.

The presents of salts causes problems in processing, such as corrosion, erosion

and plugging of equipment, and catalyst deactivation.

Sediments are solid material that are not soluble in

the hydrocarbon or water and can be comprised

of sand, drilling mud, rock or minerals coming from

erosion of metal pipes, tanks and equipment.

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Molecular Weight

Most crude oils and petroleum fractions have average molecular weights from

100 to 500.

There are several methods for measuring the molecular weight, the most suitable

method is that based on freezing point depression.

fundamentals of petroleum refining physical property...

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