PROPERTIES OF FUELS ))) 07MET.TK ((( All About Metallurgical & Materials Engineering Download This & More Stuff @ WWW.07MET.TK
Fractional Distillation Very few of the components come out of the fractional distillation column ready for market. Many of them must be chemically processed to make other fractions. For example, only 40% of distilled crude oil is gasoline; however, gasoline is one of the major products made by oil companies. Rather than continually distilling large quantities of crude oil, oil companies chemically process some other fractions from the distillation column to make gasoline; this processing increases the yield of gasoline from each barrel of crude oil.
Fractional Distillation-refining You can change one fraction into another by one of three methods: breaking large hydrocarbons into smaller pieces (cracking) combining smaller pieces to make larger ones (unification) rearranging various pieces to make desired hydrocarbons (alteration) Gasoline, kerosene, naphtha, light oils, fuel oils, diesel & coke are the result of refining the main fractions
Fractional Distillation as their boiling points increase: * melecules become larger* the liquids flow less easily (more viscous)* the liquids burn less easily* when the liquids burn, they do so with a smokier flame (soots produces due to imcomplete combustion) C36-C60 are broken down by cracking
Fractional Distillation- fuel oils Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. The term fuel oil is also used to refer to the heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha. Distillate fuel oils are distilled from crude oil. Residual fuel oils are obtained at bottom of column. Refining of heavy fuel oils can produce lighter fuels.
Fuel oil classes Fuel oil is classified into six classes, numbered 1 through 6 boiling point, composition and purpose. The boiling point, ranging from 175 to 600 °C, and carbon chain length, 20 to 70 atoms. Viscosity, b.p & C chain length all increase with number, and the heaviest oil has to be heated to get it to flow. Price usually decreases as the fuel number increases.
Fuel oil classes No. 1 fuel oil, No. 2 fuel oil and No. 3 fuel oil are variously referred to as distillate fuel oils, diesel fuel oils, light fuel oils, gasoil or just distillate. No. 2 fuel oil, No. 2 distillate and No. 2 diesel fuel oil are almost the same thing. diesel is different in that it also has a cetane number limit which describes the ignition quality of the fuel).
Fuels Oils Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. The heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha is also fuel oil.
Fuels Oils Included are products known as No. 1, No. 2, and No. 4 fuel oils and No. 1, No. 2, and No. 4 diesel fuels. No. 1 distillate is a petroleum distillate which meets the specifications for No. 1 heating or fuel oil as defined in ASTM D 396 and/or the specifications for No. 1 diesel fuel as defined in ASTM D 975.
Light Fuel Oils Streams obtained from distillation and cracking processes . Contain a mixture of saturated, aromatic and olefinic hydrocarbons with carbon numbers predominantly in the C9 to C30 range. Composition is complex and varies with the source of the crude oil. Extremely flammable. Flash Point <620C typical boiling range from 150 to 550°C.
Heavy Fuel Oils viscous liquids with a characteristic odour. require heating for storage and combustion. used in medium to large industrial plants, marine applications and power stations in combustion equipment such as boilers, furnaces and diesel engines. typical boiling range from 350 to 650°C. They consist of aromatic, aliphatic and naphthenic hydrocarbons, typically having carbon numbers from C20 to C50,
Fuels Oils Distillate Fuel Oils: A general classification for the petroleum fractions produced in conventional distillation operations. used for space heating on and off highway diesel engine fuel (including railroad engine fuel and fuel for agricultural machinery) and electric power generation.
Aviation Gasoline Blending Components. Naphthas which will be used for blending or compounding into finished aviation gasoline. Excludes oxygenates (alcohols, ethers), butane, and pentanes plus. Oxygenates are reported as other hydrocarbons, hydrogen, and oxygenates.
Fuel properties The pour point represents the lowest temperature at which the liquid fuel will just flow under specified conditions/pour. This is useful when transportation of fuel is concerned. Pour point limits for fuel. Delivering furnace fuel oil at temperatures below its pour point will cause “gelling/waxing” Seperation of wax from fuel. Viscosity.
Fuel properties The cloud point is a measure of the paraffinicity of a fuel oil. Middle distillate fuels begin to deposit wax & appear cloudy in appearance as they are cooled toward pour point. Cloud points usually occur at 4-50 C above pour point. A high value denotes a highly paraffinic oil. A low value denotes indicates a napthenic, aromatic or a highly cracked oil.
Fuel Properties The flash point the temperature to which a fuel can be heated before a flash appears on the surface of the oil up on exposure to a flame. A knowledge of the flash point is useful to ensure safe handling, transportation & storage of the fuel. The minimum flash point of fuels should be 380C or higher for safety. The fire point is the temp at which a fuel gives off vapors at a sufficient rate to continue to burn on the application of a flame.
Fuel Properties Viscosity is a measure of the resistance of the flow of a liquid. mm2/s S.I. unit. Determination of viscosity of residual fuel oils is a little complicated. At temp close to 380C, they deposit wax. Using the kinematic system the petroleum industry uses 1000 C as temp. Rate at which oil flows in fuel system. Ease with which it will be atomized. Preheating with heavier oils.
Fuel Properties API Gravity. An arbitrary scale expressing the gravity or density of liquid petroleum products. The measuring scale is calibrated in terms of degrees API; it may be calculated in terms of the following formula: Degrees API: 141.5 – 131.5 G The higher the API gravity, the lighter the compound. Light crudes generally exceed 38 degrees API Heavy crudes are commonly labeled as all crudes with an API gravity of 22 degrees or below.
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