Fundamentals of Petroleum Refining
Physical Property Characterization data
Lecturers:
assistant teachers
Kirgina Maria Vladimirovna
Belinskaya Natalia Sergeevna
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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
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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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Fundamentals of Petroleum Refining. Physical Property Characterization data
True Boiling Point Distillation
 is boiling point versus volume or mass
percent distilled
 is obtained through a batch
distillation test ASTM 2895
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
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
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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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Fundamentals of Petroleum Refining. Physical Property Characterization data
API Gravity
 API gravity:
API
141.5
131.5
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SG
where 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
Light crudes
Gravity
API > 38
Medium crudes
38 < API < 29
Heavy crudes
29 > API > 8.5
Very heavy crudes
API < 8.5
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Fundamentals of Petroleum Refining. Physical Property Characterization data
Pour Point
 is the lowest temperature at which the sample will flow
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
Viscosity
 The resistant to flow or the pumpability of the crude oil or petroleum
fraction is indicated by the viscosity
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
Refractive Index
 is the ratio of the velocity of light in a vacuum to the velocity of light in
the oil
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 This parameter used as a characterization parameter for petroleum
fraction composition
 is measured according to ASTM D1218
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Fundamentals of Petroleum Refining. Physical Property Characterization data
Freezing Point
 heavy oils contain heavy compounds such as waxes or asphaltenes,
which tend to solidify at low temperatures, thus restricting flow
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
Aniline Point
 is the lowest temperature at which an equal volume mixture of the
petroleum and aniline are miscible
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
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
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
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
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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) / Antiknock index (AKI) is the arithmetic
average of MON and RON.
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Fundamentals of Petroleum Refining. Physical Property Characterization data
Cetane Number
 measures the ability for auto ignition and is essentially the opposite of the octane
number.
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
Smoke Point
 The smoke point is a test measures the burning qualities
of kerosene and jet fuel.
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 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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Fundamentals of Petroleum Refining. Physical Property Characterization data
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
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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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Fundamentals of Petroleum Refining. Physical Property Characterization data
Molecular Weight
 Most crude oils and petroleum fractions have average molecular weights from
100 to 500.
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 There are several methods for measuring the molecular weight, the most suitable
method is that based on freezing point depression.
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