A Barrel Of Crude Oil Makes?
Crude oils are complex mixtures containing many
different hydrocarbon compounds that vary in appearance
and composition from one oil field to another.
Crude oils range in consistency from water to
tar-like solids, and in color from clear to black.
An "average" crude oil contains about
84% carbon, 14% hydrogen, 1%-3% sulfur, and less
than 1% each of nitrogen, oxygen, metals, and
salts. Crude oils are generally classified as
paraffinic, naphthenic, or aromatic, based on
the predominant proportion of similar hydrocarbon
molecules. Mixed-base crudes have varying amounts
of each type of hydrocarbon. Refinery crude base
stocks usually consist of mixtures of two or more
different crude oils.
Relatively simple crude oil assays are used to
classify crude oils as paraffinic(West Texas crude,
,Brent), naphthenic (Louisiana crude, Nigerian
Light), aromatic (Maya Crude), or mixed(Assam
crude). One assay method (United States Bureau
of Mines) is based on distillation, and another
method (UOP "K" factor) is based on
gravity and boiling points. More comprehensive
crude assays determine the value of the crude
(i.e., its yield and quality of useful products)
and processing parameters. Crude oils are usually
grouped according to yield structure.
Crude oils are also defined in terms of API (American
Petroleum Institute) gravity. The higher the API
gravity, the lighter the crude. For example, light
crude oils have high API gravities and low specific
gravities. Crude oils with low carbon, high hydrogen,
and high API gravity are usually rich in paraffin’s
and tend to yield greater proportions of gasoline
and light petroleum products; those with high
carbon, low hydrogen, and low API gravities are
usually rich in aromatics. The price of a crude
oil is usually based on its API gravity, with
high gravity oils commanding higher prices.
Crude oils that contain appreciable quantities
of hydrogen sulfide or other reactive sulfur compounds
are called "sour." Those with less sulfur
are called "sweet." Some exceptions
to this rule are West Texas crudes, which are
always considered "sour" regardless
of their H2S content, and Arabian high-sulfur
crudes, which are not considered "sour"
because their sulfur compounds are not highly
me about Hydrocarbon Groups?
The main constituents of petroleum can be grouped
into four categories:
Paraffin: A series of saturated straight chain
or branched hydrocarbons, the lowest members of
which are methane, ethane and propane.
Olefins: Double-bonded hydrocarbons that are
not normally present in crude oil but are formed
during refinery processing and vehicle combustion
of fuel. Olefins help improve the octane rating,
but their use may lead to gum formation or deposits
in engine intake systems.
Aromatic: Unsaturated cyclic hydrocarbons are
known as aromatics. Aromatics occur naturally
in crude oil and can also be produced in some
refining processes. Aromatics common in petrol
include benzene, toluene and xylene. Controlling
the level of aromatics directly limits evaporative
losses and exhaust emissions.
Naphthenes: Naphthenes are a class of compounds
that are saturated hydrocarbons typified by cyclic
hydrocarbon molecular structure. The general formula
for cyclic hydrocarbons is CnH2n.
Weathering Test is performed?
95% of LPG sample under consideration should
evaporate at a temperature of +2oc.
If the evaporation temperature exceeds +2oc then
there is a probability that heavier hydrocarbons
are present in LPG and if the evaporation temperature
is less then +2oc then there is a probability
that lighter fractions are more.
Significance: This test is intended to find out
the presence of heavier hydrocarbons in LPG, which
may not readily evaporate.
This test is done specially for LPG.
is Copper corrosion test?
test serves as measure of corrosivity of fuel
with copper, brass, or bronze parts of a fuel
The copper strip is polished smoothly and immersed
in the sample and put into a bomb. This is placed
into a water bath which is maintained at the specified
temperature for the specified time. The strip
is removed from the sample, washed with iso-octane
or normal heptane, and examined for evidence of
etching or discoloration. The colour of the strip
is compared with ASTM copper strip standards colour
Significance: Copper corrosion limits provides
assurance that difficulties will not be experienced
in deterioration of the copper and copper alloy
fittings and connections that are commonly used
in many types of utilization, storage and transportation
This test is required mainly for LPG, Naphtha,
SKO, HSD, ATF and MS.
is Flash Point?
The flash point of a fuel is the temperature to
which the fuel must be heated to produce a vapour/air
mixture above the liquid fuel that is ignitable
when exposed to an open flame under specified test
conditions. Flash point is important primarily from
a fuel-handling standpoint. Too low a flash point
will cause fuel to be a fire hazard, subject to
flashing, and possible continued ignition and explosion.
In addition, a low-flash point may indicate contamination
by more volatile and explosive fuels, such as gasoline.
A very important reason to maintain the flash point
as high as possible is due to the electrostatic
hazards in pumping distillate fuels.
Flash point (BIS) requirements for some petroleum
S.K.O.- 35 C
U.L.S.H.S.D.- 35 C
H.S.D.- 35 C
F.O.- 66 C
A.T.F.- 39 C
is Fire Point?
Fire point is the lowest temperature, corrected
to one atmosphere pressure (101.3 kPa), at which
the application of a test flame to the oil sample
surface causes the vapour of the oil to ignite and
burn for at least five seconds. For ordinary commercial
lubricating oils, the fire point usually runs about
30oC above the flash point .The test is carried
out in open cup rather then in a close one. ASTM
D 92 method offers the advantage of open flash point
and fire point determination. Low fire point petroleum
products are potential fire hazards.
is Smoke point?
Smoke is an indication of clean burning quality
of kerosene. Illumination depends upon the flame
dimension although it is not related to flame height.
Many paraffins may be gifted with better flame height
but illumination may be poor. Smoke point is defined
as the maximum height of flame in millimeters at
which the given oil will burn without giving smoke.
Different flame heights are obtained due to the
presence of different components such as paraffins,
naphthenes and aromatics. Aromatic contributes smoke,
hence removal of aromatics increases the smoke point.
Naphthenes with side chain one inevitably retained
to give good illumination. In India, marketable
kerosene should possess a smoke point of 18mm.
do you do Flame Height test?
This test is prescribed by Central Excise for distinguishing
kerosene from Diesels for the purpose of charging
duties. The test is similar to that of Smoke Point
except in preconditioning the sample and wick and
also in the final reading. The flame height is read
at the end of the 15th minute after the lamp is
is the significance of Aniline Point?
Aniline point is defined as the minimum temperature
at which equal volumes of anhydrous aniline and
oil mix together. Aniline being an aromatic compound
freely mixes with aromatic so a low aniline point
indicates low diesel index (because of high percentage
Significance: High aniline point indicates that
the fuel is highly paraffinic and hence has a
high Diesel index and very good ignition quality.
In case of aromatics the aniline point is low
and the ignition quality is poor.
This test is useful for calculating Diesel Index.
tell me about Diesel index?
Diesel index is a measure of ignition quality of
fuel. Diesel engine works on the principle of compression
ignition. During compression adiabatically the air
temperature reaches around 600 c, when the fuel
is finely atomised form is fed in, it instantaneously
explodes. Self ignition temperature is low for paraffins
while it is high for aromatics. Thus a fuel rich
in aromatics burns later causing ignition delay
and it gives rise to what is known as diesel knock.
For this reason all diesel fuels are processed to
have a diesel index in the range of 45 to 55.
Diesel Index = (Aniline Point in oF X oAPI)/
Significance: High aniline point indicates that
the fuel is highly paraffinic and hence a high
Diesel Index and a very good ignition quality.
In case of aromatics the aniline point is low
and the ignition quality is poor.
is Cetane Number ?
This is a measure of the tendency of diesel fuels
to knock in a diesel engine. This is determined
by CFR (Cooperative Fuels Research) engine having
a single cylinder. The sample fuel is compared with
that reference blend of known Cetane Number. The
reference fuels used are Normal Cetane (100 cetane
number) and Hepta Methyl Nonane (15 cetane number).
Cetane number is a whole number which is indicative
of the ignition quality of fuel. High Cetane Number
fuels give good ignition and reduced roughness.
The Cetane Number can also be calculated by the
Cetane Number =0.72* Diesel Index +10
Significance: Cetane number is the index of ignition
quality of a fuel. High cetane number fuel will
enhance easy starting of compression ignition
engines and lessen engine roughness.
This test is required mainly for HSD.
do you measure Reid Vapour Pressure?
Vapour pressure is an important physical property
of volatile liquids. It is the pressure that a vapour
exerts on its surroundings. Its units are kilopascals,
corrected to one atmosphere (101.3 kPa). For volatile
petroleum products, vapour pressure is used as an
indirect measure of evaporation rate. High vapor
pressures and a low distillation temperature for
10% evaporated both help cold starting. Under hot-operating
conditions, high vapor pressure also contributes
to vapor lock and increases vapor formation in fuel
In cold weather, a gasoline that is not volatile
enough may cause hard starting and poor warm-up.
In the winter months, for example, your vehicle's
engine is extremely cold before startup, and the
gasoline must have a high enough volatility to
be able to vaporize easily in a cold engine.Vapour
pressure can be measured by a variety of methods
including Reid, dynamic, static, vapour pressure
balance, and gas saturation.
The most commonly used method for crude oils
has been the Reid vapour pressure , as determined
by ASTM D323 (American Society for Testing of
Materials) method (Reid Method). This test method
determines vapour pressure at 37.8 'C (100 'F)
of petroleum products and crude oils with initial
boiling point above 0 'C (32 'F). It is measured
by saturating a known volume of oil in an air
chamber of known volume and measuring the equilibrium
pressure, which is then corrected to one atmosphere
is Octane Number?
Octane number is defined as percentage volume of
Iso-octane (2,2,4-trimethyl pentane) in a mixture
of Iso-octane and n-heptane that gives the same
knocking charactristic as the fuel under consideration.
Knocking in due to untimely burning of fuel in a
spark ignition engine, which results in loss of
power and sometimes it is powerful enough to cause
damage to engine parts. With the advent of petrol
engines of high compression ratios the tendency
of knocking has also increased. Being a blend, gasoline
responds in different ways, even in the same engine,
depending on the components present. Iso-paraffins
and aromatics have high octane number while n-paraffin’s
have very low value, unsaturates do have high octane
values but not preferred due to gum contribution.
Octane number is influenced by different factors
like speed of engine, ambient weather conditions,
altitude, combustion chamber deposits and coolant
temperature. Knocking rating is tested by CFR
engine for different purposes. Motor method gives
the octane rating of high way driving (high speed),
while research method gives for city driving (low
speed) conditions and aviation method is for aviation
gasoline.The rating can be done by either Research
Method or Motor Method. If the fuel meets the
minimum requirements in respect of Octane number
it ensures trouble free operation. Apart from
being a nuisance, the knocking in an engine may
result in loss of energy and at times may cause
severe damage to the engine.
is Antiknocking index?
The AKI of a motor fuel is the average of the Research
Octane Number (RON) and Motor Octane Number (MON)
or (R+M)/2 and it remains the most important quality
criteria for motorists. Thc Research Octane Number
(RON) simulates fuel performance under low severity
engine operation. The Motor Octane Number (MON)
simulates more severe operation that might be incurred
at high speed or high load. In practice the octane
of a gasoline is reported as the average of RON
and MON or R+M/2.
Significance: Today it is accepted that no one octane
rating covers all use. The combination of vehicle
and engine can result in specific requirements for
octane that depend on the fuel. If the octane is
distributed differently throughout the boiling range
of a fuel, then engines can knock on one brand of
87 i.e (RON+MON)/2, but not on another brand. This
"octane distribution" is especially important
when sudden changes in load occur, such as high
load, full throttle, and acceleration. Optimum performance
and fuel economy is achieved when the AKI is adequate
for the engine in which it is combusted. There is
no advantage in using gasoline with a higher AKI
than the engine requires to operate knock-free.
In India Current BIS specification of AKI is 84
(unleaded regular) and 88 (unleaded premium).
determines my car's octane requirements?
Your car's octane requirements are mainly determined
by its basic design. In addition, variations in
engines due to manufacturing tolerances can cause
cars of the same model to require a different octane
of several numbers. Also, as a new car is driven,
its octane requirement can increase because of the
buildup of combustion chamber deposits. This continues
until a stable level is reached, typically after
about 15,000 miles. The stabilized octane requirement
may be 3-6 numbers higher than when the car was
Other factors also influence your car's knocking
Temperature: Generally, the hotter the ambient
air and engine coolant, the greater the octane
Altitude: The higher the altitude above sea level,
the lower the octane requirement. Modern computer-controlled
engines adjust spark timing and air-fuel ratio
to compensate for changes in barometric pressure,
and thus the effect of altitude on octane requirement
is smaller in these vehicles.
Humidity: The drier the air, the greater the octane
requirement. The recommendations that vehicle
manufacturers give are for normal- to low-humidity
spark timing: The octane requirement increases
as the spark timing is advanced. Both the basic
setting of the spark timing and the operation
of the automatic spark advance mechanisms are
important in controlling knock
Method of driving: Rapid acceleration and heavy
loading, such as pulling a trailer or climbing
a hill, may result in a greater octane requirement.
Stop-and-go driving and excessive idling can increase
octane requirements by causing the buildup of
combustion chamber deposits.
MTBE, or Methyl Tertiary Butyl Ether, is an ether
compound in the same boiling range as gasoline.
Ethers have an oxygen atom in each molecule and
a characteristic smell. MTBE is made by combining
isobutylene (from various refining and chemical
processes) and methanol (usually made from natural
gas). MTBE has been used as a gasoline-blending
component since 1979. Originally, it was used to
help raise the octane of gasoline. Now, it is also
used to raise the oxygen content of gasoline. The
oxygen atom in MTBE helps provide extra oxygen for
complete combustion. Ideally, an oxygenate reduces
the amount of unburned hydrocarbons and carbon monoxide
in the exhaust. Chemical formula for MTBE is CH3OC
me about Oxygenates?
Finished motor gasoline, having oxygen content of
2.7 percent or higher by weight is known as Oxygenated
Gasoline. “Oxygenated gasoline" is a
mixture of conventional gasoline and one or more
combustible liquids which contain oxygen ("oxygenates").
At present, the most common oxygenates are ethanol
and MTBE (Methyl Tertiary Butyl Ether). Oxygenated
gasoline reduces fuel economy an average of 2%-3%
because oxygenates contain less energy than non-oxygenated
gasoline. Oxygenated gasoline helps engines run
leaner, which helps engines, particularly older
engines, produce less carbon monoxide.
Fuel Ethanol: Blends of up to 10 percent by volume
MTBE (Methyl Tertiary Butyl Ether): Blends of up
to 15.0 percent by volume MTBE which must meet the
ASTM D4814 specifications.
Other Oxygenates: Ethyl tertiary butyl ether (ETBE),
tertiary amyl methyl ether (TAME), Methanol.and
other oxygenates improve gasoline octane ratings
and reduce carbon monoxide emissions.
Viscosity is a measure of a fluid's resistance to
flow; the lower the viscosity of a fluid, the more
easily it flows. Like density, viscosity is affected
by temperature. As temperature decreases, viscosity
increases. The SI unit of dynamic viscosity is the
millipascal-second (mPa.s). “Thin” liquids,
like water or gasoline, have low viscosities; “thick”
liquids, like Lubricating oils have higher viscosities.
Viscosity is an important characteristic of diesel.
Fuels outside the required range may cause power
loss or improper atomization of the fuel in a
diesel engine. Lubrications assist in removing
the frictional forces between two moving bodies.
Absolute viscosity divided by fluid density equals
kinematic viscosity. Absolute viscosity and kinematic
viscosity are expressed in fundamental units.
Commercial viscosity such as Saybolt viscosity
is expressed in arbitrary units of time, usually
Atmospheric Crude Oil Distillation?
The refining process of separating crude oil components
at atmospheric pressure by heating to temperatures
of about 600 oF to 750 oF (depending on the nature
of the crude oil and desired products) and subsequent
condensing of the fractions by cooling.
is vacuum distillation?
A secondary refining process in which straight-run
residue is distilled in a vacuum in order to separate
more light hydrocarbons than through atmospheric
distillation. The output of the process is vacuum
gas oil, which can be used as feedstock for cracking
units, and vacuum bottoms or residue, which are
usually used as boiler fuel.
is Catalytic Cracking?
The refining process of breaking down the larger,
heavier, and more complex hydrocarbon molecules
into simpler and lighter molecules. Catalytic cracking
is accomplished by the use of a catalytic agent
and is an effective process for increasing the yield
of gasoline from crude oil. Catalytic cracking processes
fresh feeds and recycled feeds.
A refining process that uses hydrogen and catalysts
with relatively low temperatures and high pressures
for converting middle boiling or residual material
to high-octane gasoline, reformer charge stock,
jet fuel, and/or high grade fuel oil. The process
uses one or more catalysts, depending upon product
output, and can handle high sulphur feedstocks without
is Catalytic Hydrotreating ?
A refining process for treating petroleum fractions
from atmospheric or vacuum distillation units (e.g.
naphtha, middle distillates, reformer feeds, residual
fuel oil, and heavy gas oil) and other petroleum
(e.g., cat cracked naphtha, coker naphtha, gas oil,
etc.) in the presence of catalysts and substantial
quantities of hydrogen. Hydrotreating includes desulphurization,
removal of substances (e.g., nitrogen compounds)
that deactivate catalysts, conversion of olefins
to paraffins to reduce gum formation in gasoline,
and other processes to upgrade the quality of the
is Catalytic Reforming?
A refining process using controlled heat and pressure
with catalysts to rearrange certain hydrocarbon
molecules, thereby converting paraffinic and naphthenic
type hydrocarbons (e.g., low-octane gasoline boiling
range fractions) into petrochemical feedstocks and
higher octane stocks suitable for blending into
is Iso Sieve Process?
Another way of increasing octane number of gasoline
is by removing altogether low octane hydrocarbon
molecules specially straight run n-paraffin from
the product (gasoline) by physical absorption process
with the help of a specific catalyst which has the
ability to trape n-paraffin molecules.
is Delayed Coking ?
A process by which heavier crude oil fractions can
be thermally decomposed under conditions of elevated
temperatures and pressure to produce a mixture of
lighter oils and petroleum coke. The light oils
can be processed further in other refinery units
to meet product specifications. The coke can be
used either as a fuel or in other applications such
as the manufacturing of steel or aluminium.
is API gravity?
A measure of the weight of hydrocarbons according
to a scale established by the American Petroleum
Institute. Crude oils with higher values are lighter
and tend to produce larger volumes of high-value
lighter products in atmospheric distillation, which
makes them relatively more valuable. Crude oil grades
that are lower on the API scale tend conversely
to be less highly valued because they produce smaller
yields of lighter products.
API gravity = (141.5/Specific Gravity at 60F)
is Cloud Point?
Cloud point and pour point are measures of winter
temperature behavior properties of distillate fuels.
Cloud point is the temperature where paraffin first
forms in fuel.In practice, cloud point helps to
determine the temperature at which paraffin crystals
will begin to block fuel filters and lines and cause
starting and stalling problems for diesel engines.
is Pour Point ?
The pour point of an oil is the lowest temperature
at which the oil will just flow, under standard
test conditions. The failure to flow at the pour
point is usually attributed to the separation of
waxes from the oil, but can also be due to the effect
of viscosity in the case of very viscous oils. This
test is required for HSD and FO. Pour point requirement
is 6 deg C for Normal diesel and -12 deg C for winter
is Distillation standard?
The "distillation" standard is one of
several tests used to address gasoline's vaporization
characteristics. Gasoline is metered in liquid form,
through the fuel injectors (or carburetor), and
mixed with air and atomized before entering the
cylinders. Therefore, it is very important that
a fuel's tendency to evaporate is controlled to
certain standards. A fuel's ability to vaporize
or change from liquid to vapor is referred to as
In gasoline, the distillation characteristics,
along with vapor pressure, define and control
starting, warm-up, acceleration, vapor lock, crankcase
oil dilution, and, in part, fuel economy and carburetion
icing. The tendency of a fuel to vaporize is also
characterized by determining a series of temperatures
at which various percentages of the fuel have
evaporated (boiling temperatures), as described
in ASTM D86, Test Method for Distillation of Petroleum
Products. The temperatures at which 10%, 50%,
and 90% evaporation occurs are often used to characterize
the volatility of gasoline. The 10% evaporated
temperature is directly affected by the seasonal
blending of the gasoline. This temperature must
be low enough to provide easy cold starting, but
high enough to minimize the vapor lock and hot
weather driveability problems. Most cool weather
driveability problems occur from the use of summer
season gasoline in the winter months. This is
especially true in premium grades, which normally
have a high 10% evaporated temperature.
The 50% evaporated temperature must be low enough
to provide good warm-up and cool weather driveability
without being so low as to contribute to hot driveability
and vapor locking problems. This portion of the
gasoline greatly affects fuel economy on short
The 90% and end-point evaporation temperatures
must be low enough to minimize crankcase and combustion
chamber deposits, as well as spark plug fouling
and the dilution of engine oil. If the end-point
temperature exceeds the ASTM maximum requirement,
it is usually because of the presence of a distillate
fuel. This contamination can be directly attributable
to the delivery of diesel prior to the delivery
of the gasoline. This problem is avoided if care
is taken in handling the product.
is Cold filter plugging (C.F.P.P.)?
The highest temperature at which the fuel, when
cooled under the test conditions, either will not
flow through the filter or requires more than 60
sec. for 10ml to pass through. For Diesel fuel in
India specification is +6 Deg C in winter and +18
Deg C in summer.
is Fluid catalytic cracking?
FCC uses a catalyst in the form of a very fine powder
which flows like a liquid when agitated by steam,
air or vapour. Feedstock entering the process immediately
meets a stream of very hot catalyst and vaporises.
The resulting vapours keep the catalyst fluidised
as it passes into the reactor, where the cracking
takes place and where it is fluidised by the hydrocarbon
vapour. The catalyst next passes to a steam stripping
section where most of the volatile hydrocarbons
are removed. It then passes to a regenerator vessel
where it is fluidised by a mixture of air and the
products of combustion which are produced as the
coke on the catalyst is burnt off. The catalyst
then flows back to the reactor. The catalyst thus
undergoes a continuous circulation between the reactor,
stripper and regenerator sections.
The catalyst is usually a mixture of aluminium
oxide and silica. Most recently, the introduction
of synthetic zeolite catalysts has allowed much
shorter reaction times and improved yields and
octane numbers of the cracked gasolines.
Isomerisation refers to chemical rearrangement of
straight-chain hydrocarbons (paraffins), so that
they contain branches attached to the main chain
(isoparaffins). This is done for two reasons:
they create extra isobutane feed for alkylationthey
improve the octane of straight run pentanes and
hexanes and hence make them into better petrol
Isomerisation is achieved by mixing normal butane
with a little hydrogen and chloride and allowed
to react in the presence of a catalyst to form
isobutane, plus a small amount of normal butane
and some lighter gases. Products are separated
in a fractionator. The lighter gases are used
as refinery fuel and the butane recycled as feed.
Pentanes and hexanes are the lighter components
of petrol. Isomerisation can be used to improve
petrol quality by converting these hydrocarbons
to higher octane isomers. The process is the same
as for butane isomerisation.
Visbreaking, a mild form of thermal cracking, significantly
lowers the viscosity of heavy crude-oil residue
without affecting the boiling point range. Residual
from the atmospheric distillation tower is heated
(800°-950° F) at atmospheric pressure and
mildly cracked in a heater. It is then quenched
with cool gas oil to control overcracking, and flashed
in a distillation tower. Visbreaking is used to
reduce the pour point of waxy residues and reduce
the viscosity of residues used for blending with
lighter fuel oils. Middle distillates may also be
produced, depending on product demand. The thermally
cracked residue tar, which accumulates in the bottom
of the fractionation tower, is vacuum flashed in
a stripper and the distillate recycled.
is Hydrofinishing Process?
A catalytic treating process carried out in the
presence of hydrogen to improve the properties of
low viscosity-index naphthenic and medium viscosity-index
naphthenic oils. It is also applied to paraffin
waxes and microcrystalline waxes for the removal
of undesirable components. This process consumes
hydrogen and is used in lieu of acid treating.