Fuels Prelims
0.6-0.8
Specific gravity of natural gas
charcoal
-derived from destructive distillation of wood -burns rapidly with a clear flame, producing no smoke and developing heat of about 6050 cal/kg
Fuel Classifications
1. Occur in nature(Primary) or prepared(Secondary) 2. Solid, Liquid, Gas State
Combustion Carbonization Conversion
3 Pathways of Coal Utilization
Petroleum
A basic fossil fuel Dark greenish brown,viscous mineral oil found deep in earth's crust
Asphalt
A colloid of asphaltenes and maltenes that is seperated from the other components of crude by fractional distillation
Coal
A heterogeneous mineral consisting principally of carbon, hydrogen and oxygen with lesser amounts of sulfur and nitrogen
Conveyed easily through pipelines Can be lighted at ease Free from impurities
Advantages of Gaseous Fuels
Higher calorific value per unit mass than solid fuels Burn without dust, ash, clinkers, etc Easy transport through pipes
Advantages of Liquid fuels
Easy to transport Convenient to store Low cost production Moderate ignition temperature
Advantages of Solid Fuels
Diesel
Any fuel that can be used in a diesel engine Has higher density than gasoline and is simpler to refine from crude oil
Fuel Oil
Any liquid petroleum product that is burned in a furnace to generate heat
Gross calorific value
Assumes that all vapour produced during the combustion process is fully condensed
31350 kJ/kg
Average calorific value of bituminous coal
Oxygen
Basic oxidant for fuels, main oxidizer due to abundance
As-mined As-fired As-received
Basis of analysis
977 F
Boiling point of bitumen
Combustion
Burning the coal in air to liberate thermal energy
bituminous coal
Burns with a long yellow and smoky flames and has high percentages of volatile matter
35500 kJ/kg
Calorific value of anthracite
8-16
Carbon number distribution of kerosene-type jet fuel
5-15
Carbon number distribution of wide-cut or naptha-type jet fuel
a. Ash content=negligible b. Moisture=depend on age and species of the tree c. Characteristics of Flame=depends on wood content d. Combustion Characteristics=lighter wood, more intense long burning flame e. Ignition Temperature=Ignites very easily
Characteristics of wood
Paraffinic Base-saturated HC w/ little napthenes and aromatics Asphaltic Base-mainly cycloparaffins or napthenes w/ little paraffins and aromatics Mixed Base Type Crude Petroleum-both paraffinic and asphaltic/rich in semi-solid waxes
Classification of Petroleum
Parffinic, Napthenic, aromatic
Classifications of lubricating oil
Moisture content Volatile matter content Mineral/Ash content Fixed-carbon content Calorific value
Coal properties
Kerosene
Combustible liquid that is thin and clear, collected through fractional distillation at temperatures between 302-527 F Commonly used as jet fuel and as a heating fuel
Basic Requirements of a Fuel
Content Release Storage Volatility Environmental Impact
specific gravity
Density of fuel, relative to water
Propane and Butane
Different kinds of LPG
Very large tanks are needed for storage Highly flammable
Disadvantages of Gaseous Fuels
Relatively higher cost than solid fuels Costly special storage tanks Greater risks of fire hazards
Disadvantages of Liquid fuels
High ash content Large proportion oh heat is wasted Burn with clinker Difficult combustion control High cost handling
Disadvantages of Solid Fuels
83-87%-Carbon 11-16%-Hydrogen 0-4%-Oxygen plus Nitrogen 0-4%-Sulfur
Elemental composition of Petroleum
Peat
First stage in the formation of coal from wood and contains huge amt of moisture, therefore dried before use
66 C
Flash point of furnace oil
Semi-anthracite
Has less fixed carbon and less lustre than true anthracite and gives out longer and more luminous flames when burnt
Carbonization
Heating of coal to high temp in the ansence of air
105-110 C
Heating temperature to determine moisture content of air-dried coal sample
Fuel Oil
Heaviest commercial fuel that is produces from crude oil
Lignites and brown coals
Intermediate stages between peat and coal that have a woody or often clay like appearance w/(High moisture,high ash and low heat contents)
Anthracite
Is a very hard coal and has a shining black lustre Ignites slowly unless the furnace temp is high Non-caking and high percentage of fixed carbon
Methane
Main constituent if natural gas and accounting for about 95% of the total volume
Volatile Matter
Matter that is driven off when coal is heated to 950 C in the absence of air under specified conditions
Viscosity
Measure of a fluid's internal resistance to flow Decreases as the temperature increases
Stokes/Centistokes
Measurement for viscosity
Calorific Value
Measurement of heat or energy pproduced
117-147 F
Melting point of paraffin wax
Oxygen, 86%
Most abundant element in the hydrosphere
Oxygen, 47%
Most abundant element on Earth's crust
Wood
Most commonly used and easily obtained solid fuel Oldest type of fuel which man has used
Motor oil
Most commonly-known lubricating oil
Viscosity
Most important characteristic in the storage and use of fuel oil
2-4%
Normal sulfur content for the residual fuel oil
Manufactured gasses
Obtained from solid and liquid fuels
Alcohols
Oxygenated hydrocarbons where a hydrogen atom was replaced by an OH radical alcohols
Ethylene-antifreeze Propylene-acetone Benzene-explosives Toluene-solvent in refined gasoline Xylene-cleaning agent
Petrochemicals
Oxygen, 23%
Second most abundant after nitrogen in the atmosphere
-537 to -540 C
Self ignition temperature of natural gas
Distillate fuel oil Diesel fuel oil Light fuel oil Gasoil Residual fuel oil Heavy fuel oil
Six classes of fuel oil
Semi-bituminous coal
Softer than anthracite and burns with very small amount of smoke has tendency to break into small sizes during storage or transpo 15-20% volatile matter
Proximate Analysis(basics) Ultimate Analysis
Testing analysis of Solid fuels
0.03-0.07%
Typical ash value in fuel oil
Conversion
Uses various chemical processes to transform coal to gaseous or liquid fuels, called synthetic fuels
Gasoline
a mixture of paraffins, napthenes, and olefins that is mainly used as fuel in internal combustion engines
Fuel
a substance that may be burned in air that so quickly reacts with oxygen that heat and light is emitted in the form of a sustained flame
Jet Fuel
a type of aviation fuel designed for use in aircraft powered by gas-turbine engines -clear to straw colored in appearance
Specific Heat
amount of kcals needed to raise the temperature of 1 kg of oil by 1 C
Moisture
an undesirable constituent of coals because it reduces the heating value and adds to transportation costs due to its weight
Net calorific value
assumes that water leaves with the combustion products without being fully condensed
Petrochemical
chemical products made from the raw materials of petroleum
Bitumen
commonly known as tar, is a thick, black, sticky material
Lubricating oils
consists of base oils and additives
Density
defined as the ratio of the ass of the fuel to the volume of the fuel at a reference temperature of 15C
Ash
has erosive effect on the burner tips, causes damage to the refractories at high temperatures
Octane number
indicates the tendency of gasoline to knock when the compression ration in a spark ignition engine is raised (For gasoline)
Carbon Residue
indicates the tendency of oil to deposit a carbonaceous solid residue on a hot surface
Vapour pressure
indirect measure of evaporation rate
liquified petroleum gas (LPG)
is a mixture of gases that are most often used in heating appliances, aerosol propellants and refrigirants
Paraffin Wax
is a white, odorless, tasteless, waxy solid at room temperature Used in drywall to insulate buildings
Natural Gas
is generally associated with petroleum deposits and is obtained from well-dug in the oil-bearing regions
Fractional Distillation Column
is used to separate petroleum into its various constituents based on boiling points
Smoke Point
measures the tendency of a liquid fuel to form a soot
Hydrogen
most abundant element in the universe
Hard coke
obtained as a solid residue from destructive distillation in the temperature range of 1200-1400 C burns w/ smoke
Soft coke
obtained as a solid residue from destructive distillation in the temperature range of 600-605 C burns w/o smoke
Ethanol
obtained from fermentation of sugars, followed by fractional distillation
Vapour pressure
pressure that a vapor exerts on its surroundings
Methanol
produced as a product of the carbonization of wood
Cetane Number
ranks fuels according to ignition delay when undergoing standard test (for diesel)
specific gravity
ratio of the weight of a given volume of oil to the weight of the same volume of water at a given temperature
Ash Content
related to the inorganic material in the fuel oil
Calorific value
the amount of chemical energy stored in a coal that is released as thermal energy upon combustion (BTU or kJ/kg)
Refined bitumen
the bottom fraction obtained by the fractional distillation of crude oil
Pour point
the lowest temperature at which it will pour or flow when cooled under prescribed conditions
Fire Point
the lowest temperature at which the application of test flame to the oil sample surface causes the vapor of the oil engine to ignite and burn for the least five seconds
Flash Point
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
Ignition Temperature
the minimum temperature at which the material will ignite without a spark or flame being present
Fixed carbon
the solid combustible residue that remains after a coal particle is heated and the volatile matte is expelled
Briquettes
used in respect of small size waste remains of lignite, peat, coke etc. compressed into different shapes of regular form, w/ or w/o binder
