1 Introductionto Fuel

fuel & energy CH-310

Introduction to fuels

• Classification• Fundamental properties• Comparison of fuel types


Fuel

• Combustible matter used to maintain fire, as coal, wood, oil, or gas, in order to create heat or power.

• Something that gives nourishment; (food).• An energy source for engines, power plants, or

reactors. (Kerosene is used as jet engine fuel).




General Classification of Fuels• Fossil fuels:

Those which have been derived from fossil remains of plants and animal life and are found in crust of earth. For example coal, petroleum and natural gas etc.

• By-product fuels:Those which are co-product of regular manufacturing process and of secondary in nature. For example coke oven gas from manufacturing of coke and blast furnace gas from making of iron.

• Chemical fuels:Those which are of an toxic in nature and normally not used in conventional processes. For examples hydrazine, ammonium nitrate etc.

• Nuclear fuels:Those which release heat by fission (uranium, plutonium etc.) or by fusion (deuterium, tritium etc.)


Classification based on Occurrence

• Solid Fuels:Wood, charcoal, coal, coke etc.

• Liquid Fuels:petroleum and its products (gasoline, kerosene, diesel, furnace oil, lubricating oil etc), Liquid fuel from coal liquefaction etc.

• Gaseous Fuels:Natural gas, refinery gas, gas from coal gasification, wood gas, bio gas etc.


Classification based on Nature of Fuel

• Primary Fuels:Those which occurred in nature i.e. wood, coal, natural gas and petroleum.

• Secondary Fuels:Those which are derived from primary fuels e.g. fuel oil and kerosene derived from petroleum, coke oven gas derived from coal etc. Secondary fuels are further classified into:– Manufactured:

Those which are manufactured for some specific purpose e.g. coke made for iron making, gasoline made for internal combustion engine, producer gas made for industrial heating etc.

– By-Product:Those which are co-product of regular manufacturing process e.g. tar, refinery gas etc.


• FOSSIL FUEL:Are combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.• NON-FOSSIL FUEL:are alternative sources of energy that do not rely on burning up limited supplies of coal, oil, or natural gas. Examples of these fuels include: , wind or water generated energy, and solar power.


Properties of fuelCalorific value of fuel• The calorific value of a fuel is defined as the amount

of heat obtained by the complete combustion of a unit mass of the fuel.– Gross calorific value: Where the heat obtained from

condensation of water vapours in the flue gases is also include.

– Net calorific value: Where the heat obtained from condensation of water vapours in the flue gases is not include.

• GCV > NCV by an amount equal to latent heat of condensation.



Measurements of calorific value

• Bomb calorimeter(solid and non volatile liquid fuels

• Junkers gas calorimeter (gaseous fuel )

Theoretical calculations of CV discuss later


• Density• Specific gravity • 0API or API gravity is an empirical correlation which is actually a representation of specific gravity of petroleum crude or cuts (fractions)

• Baume gravity(Be’)

A higher API gravity indicates a lighter crude or oil productlow API gravity implies a heavy crude or product.Hydrometer is used for determinaton of S.G upto 0.001For higher values Specific gravity or relative density bottle is used


• ViscosityViscosity depends on the temperature and decreases as the temperature increases.Viscosity is the most important characteristic in the storage and use of fuel oil. It influences the degree of pre- heating required for handling.Viscometer is used for measurement of oil viscosity


• Viscosity indexViscosity index (VI) is an arbitrary measure for the change of viscosity with variations in temperature. The lower the VI, the greater the change of viscosity of the oil with temperature and vice versa. It is used to characterize viscosity changes with relation to temperature in lubricating oil.U =viscosity of oil sample at 100FL=viscosity of a standard oil of VI=0,at 210FH=viscosity of a standard oil of VI=100 at 210 F

• Reid Vapor PressureThe Reid Vapor Pressure (RVP) is a measure of the vapor pressure exerted by oil or by light products at 100F.It’s a measure how quickly fuel evaporate.


• Flash pointThe flash point of a fuel is the lowest temperature at which the fuel can be heated so that the vapour gives off flashes momentarily when an open flame is passed over it.

•Cleveland Open Cup Flash Point Tester•Pensky-Martens Closed Cup Flash Point Tester

• Fire pointis the minimum temperature at which the fuel vapour in admixture with air will produce a continuous fire when a fire source is brought in contact with the vapour

• Auto ignition temperaturethe lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition,Never operate a system above a fluid auto ignition temperture


• Cloud pointCloud point is the temperature at which oil becomes cloudy, when it is cooled at a specified condition.

• Pour pointPour point is the maximum temperature, at which oil ceases to flow when it is cooled at specified condition.Below pour point oil cannot be used as lubricant.High paraffin content higher pour point of crude oil.


• Smoke point The temperature at which it begins to release clouds of smoke. At that point, the oil is breaking down and has a very narrow window of time left until it burns and should be tossed out.This is an important test for evaluation of illuminating oils (kerosines) for the ability to burn without producing smoke and the assessment of burning quality of fuels.

• Char valueThe amount and nature of the deposits (char) produced on a wick during combustion depend upon the hydrocarbon composition of the fuel and also the design of the appliances in which it is used

• Soot Soot is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons


• Carbon residueCarbon residue indicates the tendency of oil to deposit a carbonaceous solid residue on a hot surface such as burner, when its vaporizable constituents evaporate

• Salt contentSalt content is typically expressed as pounds of salt (sodium chloride,NaCl) per 1000 barrels of oil (PTB).

• Sulfur contentThis is the percentage by weight (or ppm) of total sulfur content determined experimentally in a sample of oil or its product

• Volatile matterVolatile matter is any substance that has a tendency to vaporize given the right conditions.

• Water content• Ash contentThis is an indication of the contents of metal and salts present in a sample.The ash is usually in the form of metal oxides, stable salts, and siliconoxides.


• Octane number octane number of a gasoline is a measure of knocking tendencyModel fuel is 2,2,4 trimethyl pentane (100) and nheptane,is (zero)

RON(research octane number),highway conditions 900rpm MON(motor octane number),low speed city driving 600rpm PON(pump/posted octane number),average of RON & MON

• Cetane numberMeasure of the ignition quality of diesel fuel; higher this number, the easier it is to start a standard (direct-injection) diesel engine.model fuel is prepared by mixing n-hexadecane or cetane (100) and ∞-methyl naphthalene (zero)


• Aniline pointthe temperature at which the oil under test is completely miscible with equal volume of aniline, when tested in a standard apparatus.Low aniline point more aromaticsHigh aniline point more paraffins

• Diesel indexindicates quality of diesel


SOLID FUEL


LIQUID FUEL


GASEOUS FUEL

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1 Introductionto Fuel

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