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