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CRUDE CLASSIFICATION
&
PRODUCT SPECIFICATIONS
CRUDE CLASSIFICATION & PRODUCT SPECS
OVERVIEW OF PRESENTATION
CRUDE OIL
CLASSIFCATION OF CRUDE
SIGNIFICANCE OF ‘TESTS’
PRODUCT SPECIFICATION
CRUDE OIL
Petroleum : Petra – Rock, Oleum – Oil. Black Gold Crude oil is a substance, generally
liquid, occurring naturally in the earth and composed mainly of mixtures of chemical compounds of Carbon and Hydrogen with or without other nonmetallic elements such as Sulfur, Oxygen, and Nitrogen
Crude OilComplex mixture of thousands of chemical compounds that are mostly composed of Carbon and Hydrogen (called Hydrocarbons) ranging from one to 90 carbon atoms
Contains small amount of Sulphur (upto 5 %)Oxygen (upto 5 %)Nitrogen (upto 1 %)Metals (upto 0.1 %)
Most of the above are chemically combined with carbon and hydrogen and treated as impurities and contaminant
CRUDE OIL
COMPOSITION :-
Parafinic NapthenicAromatic
AVERAGE OF CRUDE OIL COMPOSITION :-
Carbon : 84%Hydrogen : 14%Sulfur : 1 - 3%Remaining : 1%(Nitrogen, Oxygen& Metal salts)
Source: BP Stats 2006
CLASSIFCATION OF CRUDE OILS
Sulfur• Sweet : S < 0.5%•Intermediate : 0.5% < S < 1.0%•Sour : 1.0% < S < 2.0%•Highly Sour : S >2.0% ACIDITY
Low Acidicty : TAN < 0.5High Acidity : TAN > 1.0
CRUDE OIL CHARACTERISTICS
Crude density is commonly measured by API gravityAPI gravity provides a relative measure of crude oil density …
the higher the API number, the lighter the crude.
Classified as light, medium or heavy Light crude are easier to process Heavy crude are more difficult to process
Sulfur content measures if a crude is sweet ( low sulfur) or sour ( higher sulfur)
Less than 0.5% sulfur content = sweet
Greater than 1.0% sulfur content = sour
High sulfur crude require additional processing to meet regulatory specs.
Acid content measured by Total Acid Number (TAN)
Acidic crude highly corrosive to refinery equipment.
High acid crude are those with TAN > 0.7
BENCH MARK CRUDES
• BRENT : North Sea
• West Texas Intermediate : North America
• Dubai : Middle East flowing to Asia Pacific region
• Tapis : Malaysian - Lt. Far East Oils
•Minas : Indonesian – Hy. Far East oils
• OPEC Reference Basket : A weighted average of oil blends of various OPEC countries.
API GRAVITY
Definition:- It is a measure of the weight of hydrocarbons according to a scale established by the American Petroleum Institute.
141.5API gravity = ---------------------------- - 131.5
Specific gravity at 600F
Significance :- This is used widely to classify the type of crude.
The Total Acid Number is the amount of Potassium Hydroxide in milligrams that is needed to neutralize the acids in one gram of oil. It is an important quality measurement of Crude oil.
Significance :
The TAN value indicates to the crude oil refinery the potential of corrosion problems.
TOTAL ACID NUMBER
Factors affecting crude selectionChoice of crude oil for a refinery depends
on many factors: Product mix Product quality Refinery configuration Product treatment facilities Refinery design spec- Metallurgy, desalter etc Environment stipulation for pollution control
For inland refinery, even pipeline design plays a role
PRODUCT SPECIFICATIONS
WHAT IS PRODUCT SPECIFICATION?THE REQUIREMENT THAT THE PRODUCT HAS TO MEET
MAY BE TECHNICAL (FUNCTIONAL / HANDLING
REQUIREMENT) OR ECOLOGICAL.
THE REQUIREMENT IS SPECIFIED AS A ‘STANDARD’ SET OF
QUALITY PARAMETERS WITH SPECIFIC QUANTITATIVE
VALUE.
THE SET OF QUANTIFIABLE QUALITY PARAMETERS IS
TERMED AS ‘SPECIFICATION’
PRODUCT IS SUBJECTED TO ‘TESTS’ TO CHECK ITS
COMPLIANCE TO THE QUALITY SPECS
EXAMPLES OF QUALITY PARAMETERS ARE DENSITY,
SMOKE POINT, OCTANE NUMBER, CETANE NUMBER
WHY SPECIFICATIONS?EACH QUALITY PARAMETER IN A SPECIFICATION HAS A SIGNIFICANCE
IT EITHER IMPROVES PERFORMANCE (OF ENGINE AS IN OCTANE & CETANE NUMBER) OR ENHANCES SAFETY (AS IN FLASH POINT), HANDLYING (AS IN POUR POINT) OR REDUCES POLLUTION (AS IN SULPHUR CONTENT, BENZENE CONTENT)
SPECIFICATION BECOMES MORE STRINGENT WITH ADVANCEMENT OF TIME, TECHNOLOGY & CUSTOMER / SOCIAL DEMANDS.
STANDARD QUALITY CONTROL PARAMETERS
FOLLOWING ARE SOME PROMINENT QUALITY CONTROL PARAMETERS:
DENSITY DISTILLATION RANGE FLASH POINT FIRE POINT OCTANE NUMBER CETANE NUMBER DIESEL INDEX SULFUR CONTENT SMOKE POINT POUR POINT
PRODUCT BLENDING IS CONTROLED TO ENSURE COMPLIANCE TO PRODUCT SPECIFICATION.
FLASH POINT
Definition :- The flash point of a fuel is the lowest temperature at which the application of a flame causes the vapour above the sample to ignite.
Significance
It is important primarily from a fuel-handling standpoint. Too low a flash point will cause fuel to be a fire hazard. A low-flash point may indicate contamination by more volatile and explosive fuels / fractions. Flash point (BIS) requirements for some petroleum products are:
S.K.O - 350 C U.L.S.H.S.D. - 350 CH.S.D - 350 CF.O. - 660C A.T.F - 380 C
FIRE POINT
Definition :- Fire point is the lowest temperature, corrected to one atmosphere pressure at which the application of a test flame to the oil sample surface causes the vapour of the oil to ignite and burn for 5 secs. Significance :-
Low fire point petroleum products are potential fire hazards.
SMOKE POINT
Definition :- It is defined as the maximum height of flame in millimeters at which the given oil will burn without giving smoke in a standard lamp under specified conditions. Significance :- Smoke point is an indication of clean burning quality of kerosene.
In India, marketable kerosene should possess a smoke point of 18mm.
ANILINE POINT
Definition :- Aniline point is the lowest temperature at which oil is completely miscible with an equal volume of Aniline. 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.
DIESEL INDEX
Definition :- Diesel index is a measure of ignition quality of fuel. Diesel Index = (Aniline Point in oF X oAPI) -----------------------------
100Significance :- High Diesel index indicates better ignition quality. Used as a guide in the absence of an engine for testing Cetane No.
CETANE NUMBER
Definition :-
This is a measure of the tendency of diesel fuels to knock in a diesel engine.
It is determined in a single cylinder CFR engine by comparing the ignition delay characteristics of the fuel with that of the reference blends of known Cetane no.
Reference fuels : Normal Cetane – 100 Heptamethyle nonane 15
Significance :- It 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.
OCTANE NUMBER
Definition :-
It is defined as percentage volume of Iso-octane in a mixture of Iso-octane and n-heptane that gives the same knocking characteristic as the fuel under consideration.
Reference fuel : iso –Octane – 100 n-Heptane - 0
Significance :- High Octane number reduces knocking in a petrol engine and improves engine life.
OXYGENATES IN GASOLINE
Definition :-
Motor gasoline, having oxygen content of 2.7 percent or higher by weight is known as Oxygenated Gasoline. Significance :- Oxygenated gasoline helps engines run leaner, which helps engines, particularly older engines, produce less carbon monoxide. Common oxygenates are MTBE (Methyl Tertiary Butyl Ether) & Ethanol.
CLOUD POINT
Definition :- Cloud point is the temperature at which a cloud or haze of wax crystals appears at the bottom of the test jar when the oil is cooled under the prescribed conditions.
Significance :- It indicates the temperature above which oil can be safely handled without any fear of congealing or filter clogging.
POUR POINT
Definition :- Pour point is the lowest temperature in multiples of 3 Deg. C at which the oil will just flow when cooled under prescribed conditions. Significance :- It indicates the pumpability of the fuel and it indicates the waxy nature of the fuel.
Unit Value
Total volatile sulfur ppmwt 200 max.
Evaporation temperature for 95 vol%
°C 2 max.
Vapor pressure @ 40 °C kPa 1050 max.
Mercaptan sulfur ppmwt 50-150
Hydrogen sulfide ppmwt Nil
Free water ppmwt Nil
LPG
Unit Value
Paraffins vol% 65 min.
Aromatics vol% 10 max.
Olefins vol% 1 max.
Density kg/m³ Free
IBP °C 34 min.
FBP °C 160 max.
Sulfur wt% 0.15 max.
RVP @ 38 °C psi 10 max.
NAPHTHA
EURO III EURO IV
Premium Regular Premium Regular
Unit Value Value Value Value
RON unleaded - 95 min. 91 min. 95 min. 91 min.
MON unleaded - 85 min. 81 min. 85 min. 81 min.
Density kg/m³ 720-775 720-775 720-775 720-775
Evaporation at 70 °C
vol% 10-45 10-45 10-45 10-45
Motor Spirit
EURO III EURO IV
Premium Domestic Premium Domestic
Evaporation at 100 °C
vol% 40-70 40-70 40-70 40-70
Evaporation at 150 °C
vol% 75 min. 75 min. 75 min. 75 min.
Final Boiling Point
°C 210 max. 210 max. 210 max. 210 max.
Sulfur wt% 0.015 max.
0.015 max.
0.005 max.
0.005 max.
Motor Spirit
EURO III EURO IV
Premium Domestic Premium Domestic
RVP @ 38°C kPa 60 max. 60 max. 60 max. 60 max.
Benzene vol% 1 max. 1 max. 1 max. 1 max.
Aromatics vol% 42 max. 42 max. 35 max. 35 max.
Oxygen content
wt% 2.7 max. 2.7 max. 2.7 max. 2.7 max.
Oxidation stability
mints 360 min. 360 min. 360 min. 360 min.
Olefin content vol% 18 max. 21 max. 18 max. 21 max.
Motor Spirit
Unit Value
Density @ 15 °C kg/m³ 775-840
Smoke point mm 19 min.
Freezing point °C - 47 max.
Color Saybolt - +10 min.
Distillation, 10 vol% °C 205 max.
Distillation, FBP °C 300 max.
Copper Strip Corrosion, 3 hrs @ 50 °C - Not worse than No.1
JET FUEL
Unit Value
Sulfur wt% 0.25 max.
Flash point °C 38 min.
Viscosity @ -20 °C mm2/s 8.0 max
Naphthalene content vol% 3.0 max.
Silver Strip Corrosion, 16 hrs @ 45 °C - 0 max.
Thermal stability (JFTOT) mm Hg 25 max.
Water Separation Index Modified (WSIM)
- 70 min.
JET FUEL
EURO III EURO IV
Unit Value Value
Density @ 15 °C kg/m³ 820-845 820-845
Cetane Index min. 46 48
Cetane Number (Note 1) min. 51 51
CFPP, Winter / Summer °C, max. 6 / 18 6 / 18
Water content vol%max
0.02 0.02
Distillation, 85 vol% °C max 350 350
DIESEL
Distillation, 95 vol% °C 360 max. 360 max.
Viscosity @ 40 °C cSt 2 – 4.5 2 – 4.5
Sulfur ppm max.
350 50
Flash point °C min. 35 35
Polycyclic Aromatic Hydrocarbons (PAH)
wt% max. 11 11
Lubricity @ 60 °C microns max.
460 460
Copper Strip Corrosion, 3 hrs @ 50 °C
- No. 1 No. 1
DIESEL
Regular Fuel Oil
Plant Fuel Oil
Unit Value Value
Density @ 15 °C kg/m³ free free
Flash point °C min.
66 66
Pour point (Note 1) °Cmax.
27 -
Kinematic Viscosity @ 50 °C cStmax.
180 8,500-50,000
Sulfur wt%max.
4.0 1.8
FUEL OIL
CRUDE OIL CLASSIFICATION
Definition :-
Based on the predominant proportion of similar Hydrocarbon molecules, crude oils are classified based on API gravity / density and sulfur content. Crude oils are also classified based on quality of Hydrocarbon Sulfur and other reactive Sulfur components.
Crude oil with less Sulfur is called “SWEET”
Crude oil with more Sulfur is called “SOUR”
India - Oil & Gas Resources
Crude Oil Reserves: 786 mtoe/5.9 bln bbl (end 2005)Production: 36.2 mln ton/816 tbpd (2005)
Natural GasReserves: 1101 bcm (end 2005)Production: 30.4 bcm (2005)
Source: BP Stats 2006
WHAT IS A PETROLEUM PRODUCT ?
A PRODUCT IS SOMETHING THAT SATISFIES A NEED & CONSEQUENTLY HAS ECONOMIC VALUE
PETROLEUM PRODUCT IS AN ENGINEERED MATERIAL THAT MEETS THE REQUIREMENT
A PETROLEUM PRODUCT EX. GASOLINE, DIESEL, LPG IS A HOMOGENEOUS MIXTURE OF PETROLEUM FRACTIONS THAT IS BLENDED IN A CONTROLLED MANNER TO MEET THE REQUIREMENT
HISTORY OF REFINING
Year
Process name
Purpose
By-products, etc.
1862 Atmospheric distillation Produce kerosene Naphtha, tar, etc.
1870 Vacuum distillation Lubricants (original) Cracking feedstocks (1930's)
Asphalt, residual coker feedstocks
1913 Thermal cracking Increase gasoline Residual, bunker fuel
1916 Sweetening reduce sulfur & odor Sulfur
1930 Thermal reforming Improve octane number Residual
1932 Hydrogenation Remove sulfur Sulfur
1932 Coking Produce gasoline basestocks Coke
1933 Solvent extraction Improve lubricant viscosity index
Aromatics
1935 Solvent dewaxing Improve pour point Waxes
1935 Cat. Polymerization Improve gasoline yield & octane number
Petrochemical feedstocks
1937 Catalytic cracking Higher octane gasoline Petrochemical feedstocks
1939 Visbreaking reduce viscosity Increased distillate,tar
HISTORY OF REFINING
Year
Process name
Purpose
By-products, etc.
1940 Alkylation Increase gasoline octane & yield
High-octane aviation gasoline
1940 Isomerization Produce alkylation feedstock Naphtha
1942 Fluid catalytic cracking Increase gasoline yield & octane
Petrochemical feedstocks
1950 Deasphalting Increase cracking feedstock Asphalt
1952 Catalytic reforming Convert low-quality naphtha Aromatics
1954 Hydrodesulfurization Remove sulfur Sulfur
1956 Inhibitor sweetening Remove mercaptan Disulfides
1957 Catalytic isomerisation Convert to molecules with high octane number
Alkylation feedstocks
1960 Hydrocracking Improve quality and reduce sulfur
Alkylation feedstocks
1974 Catalytic dewaxing Improve pour point Wax
1975 Residual hydrocracking Increase gasoline yield from residual
Heavy residuals
TYPICAL APPROXIMATE CHARACTERISTICS AND PROPERTIES AND GASOLINE POTENTIAL OF VARIOUS CRUDES
(Representative average numbers)
Crude source
Paraffins (% vol)
Aromatics (% vol)
Naphthenes (% vol)
Sulfur (% wt)
API gravity
(approx.)
Napht. yield (% vol)
Octane no
(typical)
Nigerian -Light
37 9 54 0.2 36 28 60
Saudi -Light
63 19 18 2 34 22 40
Saudi -Heavy
60 15 25 2.1 28 23 35
Venezuela -Heavy
35 12 53 2.3 30 2 60
Venezuela -Light
52 14 34 1.5 24 18 50
USA -Midcont. Sweet
- - - 0.4 40 - -
USA -W. Texas Sour
46 22 32 1.9 32 33 55
North Sea -Brent
50 16 34 0.4 37 31 50
TYPICAL ALKENES.
Simplest Alkene (C2H4):
Typical Alkenes with the same chemical formula (C4H8) but different molecular structures:
ETHYLENE (C2H4) 1-BUTENE (C4H8) ISOBUTENE (C4H8)
TYPICAL APPROXIMATE CHARACTERISTICS AND PROPERTIES AND GASOLINE POTENTIAL OF VARIOUS CRUDES
(Representative average numbers)
Crude source
Paraffins (% vol)
Aromatics (% vol)
Naphthenes (% vol)
Sulfur (% wt)
API gravity
(approx.)
Napht. yield
(% vol)
Octane no
(typical)
Nigerian Light 37 9 54 0.2 36 28 60
Saudi Light 63 19 18 2 34 22 40
Saudi Heavy 60 15 25 2.1 28 23 35
Venezuela Heavy 35 12 53 2.3 30 2 60
Venezuela Light 52 14 34 1.5 24 18 50
USA Midcont. Sweet
- - - 0.4 40 - -
USA-W. Texas Sour
46 22 32 1.9 32 33 55
North Sea Brent 50 16 34 0.4 37 31 50
CRUDE INPUT CONSISTS OF
INDIGENOUS CRUDE ASSAM & NORTH /SOUTH GUJRAT ARE MAIN
ONSHORE CRUDES. BOMBAY HIGH, RAVVA, PANNA MUKTA ARE MAIN
OFF-SHORE CRUDE. SUPPLY IS LOWER THAN REQUIREMENT CHEAPER COMPARED TO IMPORTED CRUDE DUE
TO DUTY/TAX AND FREIGHT ADVANTAGE .
IMPORTED CRUDE HIGH SULPHUR LOW SULPHUR
TYPICAL AROMATICS. Example of simple aromatic compound: Examples of simple double-ring aromatic
compound:
BENZENE (C6H6) NAPTHALENE (C10H8)
SOURCING OF CRUDE OIL
• INDIGENOUS CRUDE• MAINLY BASED ON GOVT.,
ALLOCATION
• IMPORTED CRUDE• TERM CONTRACT
• TERM TENDER
• SPOT TENDER
CRUDE OILGRADATION OF CRUDE OIL
BASED ON PRODUCTION CAPABILITY OF PARTICULAR PRODUCT
BITUMENIOUS (BASRA, KUWAIT, AM) NON-BITUMENIOUS HIGH SULFUR (INDIAN,
MALAYSIAN, OMAN) LUBE (AM, BASRA,MURBAN) NON LUBE (KUWAIT,MASILA) ATF NON-ATF
Key features with indigenous crude
LPG, Naphtha will be on spec
SKO ex-Assam crude would need de-aromatisation / hydro treatment for improvement of smoke point
Diesel ex-Assam crude requires hydrotreating or addition of cetane improver.
Mostly non-ATF (excepting Gujarat crudes)
Non-Bituminous, therefore all residue converted to LSHS
CRUDE OIL
GRADATION OF CRUDE OIL BASED ON SULFUR CONTENT
LOW SULFUR ,Sulfur , <0.5 %wt ( INDIAN, MALAYSIAN, WAF) HIGH SULFUR , Sulfur , >0.5 %wt (LATIN AMERICAN, PG)
BASED ON API GRAVITY LIGHER, API>30( INDIAN, MALAYSIAN, WAF) HEAVIER API<30 (LATIN AMERICAN, PG)
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