2. SHAMIM HASN { DEPT OF ACCE(1ST
BATCH)}
ENERGY
Energy causes things to happen around us. Look out the window.
During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to
light our way.
When a car driven by, it is being powered by gasoline, a type of stored energy.
The food we eat contains energy. We use that energy to work and play.
We learned the definition of energy in the introduction:
"Energy Is the Ability to Do Work."
Energy can be found in a number of different forms. It can be;
Chemical energy,
Electrical energy,
Heat (thermal energy),
Light (radiant energy),
Mechanical energy and
Nuclear energy etc.
Stored and Moving Energy
Energy makes everything happen and can be divided into two types:
Stored energy is called potential energy
Moving energy is called kinetic energy
With a pencil, try this example to know the two types of energy.
Put the pencil at the edge of the desk and push it off to the floor. The moving pencil uses kinetic energy,
Now, pick up the pencil and put it back on the desk. You used your own energy to lift and move the
pencil. Moving it higher than the floor adds energy to it. As it rests on the desk, the pencil has potential
energy. The higher it is, the further it could fall. That means the pencil has more potential energy.
ENERGYIS IMPORTANT
Energy is everywhere. Anything we eat or use has energy embodied in it. Every object we produce
required energy to make and/ or energy to transport, and the energy demands are closely linked to the
economic growth of a country
Energy is very, very important because everything that we consume, use, eat is energy or has energy
embodied in it. A piece of paper has used energy or had energy used to create it and transport it to where
it is, so although it only contains a little bit of energy, there has actually been a huge amount of energy
used to get it to where it is. And it’s the same with the chair you sit on and the shampoo you wash your
hair with. So energy is embodied in everything that we use, and in order to have economic growth, we
need to have lots of energy and preferably nice and cheap energy. So not only do we need carbon neutral
energy, we need large quantities of it.
3.
4. FUEL
A material used to produce heat or power by burning
OR
something that gives support or strength to something
Fuel is a substance which, when burnt, i.e. on coming in contact and reacting with oxygen or air, produces
heat. Thus, the substances classified as fuel must necessarily contain one or severalof the combustible
elements: carbon, hydrogen, Sulphur, etc. In the process of combustion, the chemical energy of fuel
converted into heat energy
COMBUSTION: -
A Combustion Reaction is a reaction in which oxygen reacts with another element or compound
(Generally a hydrocarbon) to produce energy in the form of heat and light.
An example might be the combustion of methane
5. Two Types ofCombustion:-
Complete Combustion:-
Clean combustion with a hydrocarbon produces carbon-dioxide and water.
Incomplete Combustion:-
Dirty combustion with a hydrocarbon produces carbon and/or carbon monoxide as well as carbon
dioxide.
CLASSIFICATIONOF FUELS:-
Fuels may broadly be classified in two ways, i.e.
According to the physical state in which they exist in nature – solid, liquid and gaseous, for
example:
PRIMAY SECONDARY
Solid Fuels Solid Fuels
Wood, Peat,Brown coal, Bituminous, tarsands,
shales
Semi-coke, coke, charcoal, Petroleum, solid
rocket fuel
Liquid Fuels Liquid Fuels
Crude oil or petroleum Gasoline, motor spirit, diesel, kerosene, coal tar
Gaseous Fuels Gaseous Fuels
Natural gas Coal gas, blast furnace gas,oil gas, LPG, water
gas
According to the mode of their procurement – natural and manufactured.
None of these classifications, however,gives an idea of the qualitative or intensive value of the fuels, i.e.
their power of developing the thermal intensity or calorimetric temperature under the normal condition of
use, i.e. combustion of fuels in mixture with atmospheric air in stoichiometric proportion.
6. Destructive Distillation of Coal
When coal is heated without air, it does not burn but produces many by-products. This process of heating
coal in the absence of air is called destructive distillation of coal.
The main by products are:
Coke (solid fuel)
coal tar
amino acid liquor
coal gas (gaseous fuel)
SOLID FUELS AND THEIR CHARACTERISTICS
Solid fuels are mainly classified into two categories, i.e. natural fuels, such as wood, coal, etc. and
manufactured fuels, such as charcoal, coke, briquettes, etc.
The various advantages and disadvantages of solid fuels are given below :
Advantages
(a)They are easy to transport.
(b)They are convenient to store without any risk of spontaneous explosion.
(c)Their cost of production is low.
(d)They posses moderate ignition temperature.
7. Disadvantages
(a) their ash content is high.
(b)Their large proportion of heat is wasted.
(c)They burn with clinker formation.
(d)Their combustion operation cannot be controlled easily.
(e)Their cost of handling is high.
LIQUID FUELS AND THEIRCHARACTERISTICS
The liquidfuelscanbe classifiedasfollows:
(a)Natural orcrude oil,and
(b)Artificial ormanufacturedoils.
The advantagesand disadvantagesof liquidfuelscanbe summarizedasfollows:
Advantages
(a)Theyposseshighercalorificvalue perunitmassthansolidfuels.
(b)Theyburnwithoutdust,ash,clinkers,etc.
(c) Theirfiringiseasierandalsofire can be extinguishedeasilybystoppingliquidfuel supply.
(d)Theyare easytotransport throughpipes.
(e)Theycanbe storedindefinitelywithoutanyloss.
(f)Theyare cleaninuse andeconomicto handle.
(g)Lossof heatin chimneyisverylowdue togreatercleanliness.
(h)Theyrequire lessexcessairforcomplete combustion.
(i)Theyrequire lessfurnace space forcombustion.
8. Disadvantages
(a)The cost of liquid fuel is relatively much higher as compared to solid fuel.
(b)Costly special storage tanks are required for storing liquid fuels.
(c)There is a greater risk of five hazards, particularly, in case of highly inflammable and volatile liquid
fuels.
(d)They give bad odor.
(e)For efficient burning of liquid fuels, specially constructed burners and spraying apparatus are required.
GASEOUS FUELS AND THEIR CHARACTERISTICS
Gaseous fuels occur in nature, besides being manufactured from solid and liquid fuels.
1) Water gas:
A mixture of carbon monoxide and hydrogen gas is commonly known as water
gas. [CO + H2] = Water gas
it is used as a fuel.
PREPARATION:
It is prepared by passing steam over red hot coke.
C + H2O = CO + H2
2) Coal gas:
Coal gas, gaseous mixture—mainly hydrogen, methane, and carbon monoxide—formed by the
destructive distillation (i.e., heating in the absence of air) of bituminous coal and used as a fuel.
Sometimes steam is added to react with the hot coke, thus increasing the yield of gas. Coal tar and coke
are obtained as by-products.
9. 3) Natural Gas:
Natural gas is a vital component of the world's supply of energy. It is one of the cleanest, safest,and most
useful of all energy sources.
Natural gas is a combustible mixture of hydrocarbon gases. While natural gas is formed primarily of
methane, it can also include ethane, propane, butane and pentane. The composition of natural gas can vary
widely, but below is a chart outlining the typical makeup of natural gas before it is refined.
4) Bio Gas:
Biogas is produced by anaerobic digestion with anaerobic bacteria or fermentation of biodegradable
materials such as manure, sewage,municipal waste,green waste, plant material, and crops.[1]
Biogas
comprises primarily of methane (CH
4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H
2S), moisture and siloxanes.
The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen.
This energy release allows biogas to be used as a fuel. Biogas can be used as a fuel in any country for any
heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into
electricity and heat.
10. Some examples ofGaseous Fuels
NAME COMPOSITION USES
Water Gas C + H2O = CO + H2 Fuels in industries
Preparation of NH3
Natural Gas CH4 =85%
C2H6=10%
Hydrocarbons= 5%
Cooking
Fuel
Coal Gas H2 =50%
CH4=25-35%
CO=4-10%
Industrial fuel
Bio Gas Gobar Gas:
CH4=50%
CO2=35%
Organic Waste
Power generation
Vehicle fuel
The advantages and disadvantages of gaseous fuels are given below:
Advantages
Gaseousfuelsdue toerase andflexibilityof theirapplicationspossessthe followingadvantages over
solidorliquidfuels:
(a)Theycanbe conveyedeasilythroughpipelinestothe actual place of need,therebyeliminating
manual laborin transportation.
(b)Theycanbe lightedatease.
(c)Theyhave highheatcontentsandhence helpusinhavinghighertemperatures.
(d)Theycanbe pre-heatedbythe heatof hot waste gases,therebyaffectingeconomyinheat.
(e)Theircombustioncanreadilybycontrolledforchange indemandlike oxidizingorreducing
atmosphere,lengthflame,temperature,etc.
(f) theyare cleanin use.
(g)Theydonotrequire anyspecial burner.
(h)Theyburnwithoutanyshoot,orsmoke andashes.
(i)Theyare free fromimpuritiesfoundinsolidandliquidfuels.
Disadvantages
(a) Very large storage tanks are needed.
(b)They are highly inflammable, so chances of fire hazards in their use are high.
13. Fractional Distillation
The various components of crude oil have different sizes, weights and boiling temperatures; so, the first
step is to separate these components. Because they have different boiling temperatures,they can be
separated easily by a process called fractional distillation. The steps of fractional distillation are as
follows:
1. You heat the mixture of two or more substances (liquids) with different boiling points to a high
temperature. Heating is usually done with high pressure steam to temperatures of about 1112
degrees Fahrenheit / 600 degrees Celsius.
2. The mixture boils,forming vapor (gases); most substances go into the vapor phase.
3. The vapor enters the bottom of a long column (fractional distillation column) that is filled with
trays or plates. The trays have many holes or bubble caps (like a loosened cap on a soda bottle) in
them to allow the vapor to pass through. They increase the contact time between the vapor and
the liquids in the column and help to collect liquids that form at various heights in the
column. There is a temperature difference across the column (hot at the bottom, cool at the top).
4. The vapor rises in the column.
5. As the vapor rises through the trays in the column, it cools.
6. When a substance in the vapor reaches a height where the temperature of the column is equal to
that substance's boiling point, it will condense to form a liquid. (The substance with the lowest
boiling point will condense at the highest point in the column; substances with higher boiling
points will condense lower in the column.).
7. The trays collect the various liquid fractions.
8. The collected liquid fractions may pass to condensers, which cool them further, and then go to
storage tanks, or they may go to other areas for further chemical processing
Fractional distillation is useful for separating a mixture of substances with narrow differences in boiling
points, and is the most important step in the refining process.
14. The oil refining process starts with a fractional distillation column. On the right, you can see several
chemical processors that are described in the next section.
Veryfewof the componentscome outof the fractional distillationcolumnreadyformarket.Manyof
themmustbe chemicallyprocessedtomake otherfractions.Forexample,only40% of distilledcrude oil
isgasoline;however,gasoline isone of the majorproductsmade byoil companies.Ratherthan
continuallydistillinglarge quantitiesof crude oil,oil companieschemicallyprocesssome otherfractions
fromthe distillationcolumntomake gasoline;thisprocessingincreasesthe yieldof gasolinefromeach
barrel of crude oil.
15. USES OF OIL
Uses of by
product
Sources of
power
As a motor
fuel
As a lubricant
for machines
paraffin
wax
plastic
synthetic rubber
detergents
pharmacuetical
product
chemicalproduct
bitumenfor road
surfaces
thermal
electricity
heating
As a motor fuel
petrol
jet oil
jet petrol 1
jet petrol 4
air craft
cars
diesel
truck
16. Coal
Coal is a fossil fuel mined from ancient deposits.
It is a black mineral of plant origin which is chemically, a complex mixture of elemental carbon,
compounds of carbon containing hydrogen, oxygen, nitrogen and sulphur.
Formation ofcoal:
Coal is believed to have been formed about 300 million years ago under the Earth by a process called
carbonization.
Carbonization is the process of slow conversion of vegetable matter to coal under the Earth due to the
action of high pressure,high temperature, anaerobic bacteria and absence of oxygen.
17. Classification ofcoal:
Depending upon the extent of carbonization, coal can be classified into four types as follows:
Type ofCoal Carbon content Commonly known as
Peat (first stage) 11% -
Lignite 38% Soft coal / brown coal
Bituminous 65% Household coal
Anthracite(last stage) 96% Hard coal
Lignite coal
Used almost exclusively for electric power generation lignite is a young type of coal. Lignite is brownish
black, has a high moisture content (up to 45 %),and a high sulphur content. Lignite is more like soil than
a rock and tends to disintegrate when exposed to the weather. Lignite is also called brown coal.
Lignite has a calorific value of less than 5 kw/kg approximately.
Subbituminous coal
Subbituminous coal is also called black lignite. Subbituminous coal black and contains 20-30 % moisture.
Subbituminous coal is used for generating electricity and space heating.
Subbituminous coal has calorific values ranging from 5 - 6.8 kW/kG approximately.
Bituminous coal
Bituminous coal is a soft, dense, black coal. Bituminous coal often has bands of bright and dull material
in it. Bituminous coal is the most common coal and has a moisture content less than 20 %. Bituminous
coal is used for generating electricity, making coke, and space heating.
Bituminous coal has calorific values ranging from 6.8 - 9 kW/kG approximately.
Anthracite coal
Often referred to as hard coal, anthracite is hard, black and lustrous. Anthracite is low in sulphur and high
in carbon. It is the highest rank of coal. Moisture content generally is less than 15 %.
Anthracite has calorific values of around 9 kW/kG or above.
18. Destructive distillation ofcoal:
Laboratory method ofdestructive distillation ofcoal:
Materials required:
Two hard glass test tubes marked A and B, delivery tubes, clamp stand, burner, rubber stoppers, pieces of
coal and water.
Principle
The volatile matter present in coal escapes on heating coal to a high temperature in the absence of
oxygen.
Procedure:
Small pieces of coal are taken in test tube A.
Test tube A is fitted with a rubber stopper carrying a delivery tube and is clamped to the clamp
stand.
Test tube B containing water is clamped vertically to the clamp stand.
The apparatus is assembled as shown in the figure.
The burner is lighted and the test tube A is heated first gently and then intensely.
19. Products formed and their uses:
Product Formed/collected in Uses
Coal Tar (complex
mixture of carbon
compounds)
Bottom of the test tube B.
Liquid residue insoluble in
water
Can be distilled to obtain: Benzene —
solvent Toluene — manufacture of explosive
TNT Naphthalene — insect repellent
Coal gas (CH4+CO+H2)
Combustible gas insoluble in
water. Escapes through the side
tube
Industrial fuel
Liquor ammonia
(NH4OH)
Soluble in water present in test
tube
Manufacture of nitrogenous fertilizers
Coke (98%C)
Solid residue left behind in test
tube A
i) Reducing agent in metallurgy
ii) Manufacture of water gas and producer
gas — Industrial fuel
20. Coal analysis
The main purpose of coal sample analysis is to determine;
The rank of the coal along with its characteristics
Its proportions;
Physical parameters like;
Moisture
Volatile content
Carbon content etc.
Moisture
First of all coals are mined out wet, after that moisture is removed that is known as inherent moisture.
Inherent moisture can further be elaborated as;
Moisture Characteristic
Surface moisture Present on the surface of coal.
Hygroscopic Moisture inside the coal’s micro-fractures due to
capillary action.
Decomposition Moisture released when coal is decomposed.
Mineral moisture The moisture held with the mineral crystal that is
associated with coal.
Volatile matter
It is the pat liberated at increasing the temperature in the absence of air. This is usually a mixture of short
and long chain hydrocarbons, aromatic hydrocarbons and some amount of sulphur.
Ash content
It the noncombustible residue left after coal is burnt. It is the bulk mineral matter, after Carbon, Oxygen,
Sulphur and water is removed during combustion.
21. Fixed Carbon
It is the carbon found in the material which is left after volatile material are driven out. Fixed carbon is
used as an estimation of the amount of coke that will be yielded from the sample of coal, i.e. it is
determined by removing the mass of volatile content
Proximate Analysis
Proximate analysis indicates the percentage by weight of the Fixed Carbon, Volatiles, Ash, and Moisture
Content in coal. The amounts of fixed carbon and volatile combustible matter directly contribute to the
heating value of coal. Fixed carbon acts as a main heat generator during burning. High volatile matter
content indicates easy ignition of fuel. The ash content is important in the design of the furnace grate,
combustion volume, pollution control equipment and ash handling systems of a furnace.
Significance ofVarious Parameters in Proximate Analysis
Fixed carbon:
Fixed carbon is the solid fuel left in the furnace after volatile matter is distilled off. It consists
mostly of carbon but also contains some hydrogen, oxygen, sulphur and nitrogen not driven off
with the gases. Fixed carbon gives a rough estimate of heating value of coal
Volatile Matter:
Volatile matters are the methane, hydrocarbons, hydrogen and carbon monoxide, and
incombustible gases like carbon dioxide and nitrogen found in coal. Thus the volatile matter is an
index of the gaseous fuels present.
Volatile Matter
1. Proportionately increases flame length, and helps in easier ignition of coal.
2. Sets minimum limit on the furnace height and volume.
3. Influences secondary air requirement and distribution aspects.
4. Influences secondary oil support
22. Ash Content:
Ash is an impurity that will not burn.
Ash
1. Reduces handling and burning capacity.
2. Increases handling costs.
3. Affects combustion efficiency and boiler efficiency
4. Causes clinkering and slagging.
Moisture Content:
Moisture in coal must be transported, handled and stored. Since it replaces combustible matter, it
decreases the heat content per kg of coal.
Moisture
1. Increases heat loss, due to evaporation and superheating of vapour
2. Helps, to a limit, in binding fines.
3. Aids radiation heat transfer
Sulphur Content:
Sulphur
1. Affects clinkering and slagging tendencies
2. Corrodes chimney and other equipment such as air heaters and economizers
3. Limits exit flue gas temperature.
PROXIMATE ANALYSIS UNIT AS
RECEIVED
AIR DRIED DRYBASIS DRYASH
FREE
MOISTURE WT% 3.3 2.7 - -
ASH WT% 22.1 22.2 22.8 -
VOLATILE MATTER WT% 27.3 27.5 28.3 36.6
FIXED CARBON WT% 47.3 47.6 48.9 63.4
GROSS CALORIFIC VALUE WT% 24.73 24.88 25.5 33.13
Formulae
% moisture content of coal= loss in wt / initial wt taken of coal x 100
% volatile matter = loss in wt due to volatile matter / initial wt taken of coal x 100
23. % ash= wt of residue / initial wt taken of coal x 100
Ultimate Analysis:
The ultimate analysis indicates the various elemental chemical constituents such as Carbon, Hydrogen,
Oxygen, Sulphur, etc. It is useful in determining the quantity of air required for combustion and the
volume and composition of the combustion gases. It is done through Laser Induced Break down
Spectroscopy (LIBS)
ULTIMATE ANALYSIS UNIT AS
RECEIVED
AIR DRIED DRYBASIS DRYASH
FREE
C WT% 61.1 61.5 63.2 81
H WT% 3.0 3.02 3.10 4.0
N WT% 1.35 1.36 1.40 1.8
TOTAL S WT% 0.4 0.39 0.39 -
O WT% 8.8 8.8 9.1 -
24. CALORIFOC VALUE:
Calorific value refers to the energy contained in fuel or food, determined by measuring the heat produced
by the complete combustion of a specified quantity of it. This is usually expressed in kilo calories per
kilogram. Other names for calorific values are:
Heat of combustion,
Heating value.
CALORIE
The energystoredinfoodismeasuredintermsof calories.
Technically,1calorie isthe amountof energyrequiredtoraise the temperature of 1gram of water1
degree centigrade.
25. HIGHER CALORIFIC VALUE
Higher calorific value of a fuel portion is defined as the amount of heat evolved when a unit weight (or
volume in the case of gaseous fuels) of the fuel is completely burnt and the products of combustion
cooled to the normal conditions (with water vapor condensed as a result). The heat contained in the water
vapor must be recovered in the condensation process. Corresponding names for higher calorific value
(HCV),are:
Gross Calorific Value (GCV),
Higher Heating Value (HHV).
LOWER CALORIFIC VALUE
Lower calorific value of a fuel portion is defined as the amount of heat evolved when a unit weight (or
volume in the case of gaseous fuels) of the fuel is completely burnt and water vapor leaves with the
combustion products without being condensed. There are other names for lower calorific value (LCV),
which are:
Net Calorific Value (NCV),
Lower Heating Value (LHV).
Units
The SI unit of calorific value is Cal/k.
It may be expressed with the quantities:
energy/mole of fuel (kCal/mol)
energy/mass of fuel (Cal/gm)
energy/volume of fuel (BTU/lb)
26. CONVERSIONS
Otherheatingvalue unitconversions
Kcal/kg= MJ/kg * 238.846
Btu/lb= MJ/kg * 429.923
Btu/lb= kcals * 1.8
The heat of combustionforfuelsisexpressedasthe HCV,LCV, or GCV.
THEROTICALDETERMINATION
GROSS CALORIFIC VALUE
The gross calorific value of a substance is the number of heat units that are liberated when a unit weight
of that substance is burned in oxygen, and the residual materials are oxygen, carbon dioxide, sulphur
dioxide, nitrogen, water,and ash. The energy content of biological materials has been expressed
traditionally in calories (c) or kilocalories (C) per gram dry weight. Sometimes results are expressed more
significantly in terms of ash-free dry weight, i.e. in terms of organic constituents only. Contemporary
studies of ecological energetic express results in terms of the SI energy unit, the joule (4,182 J = 1
calorie).
DULONG’S FORMULA
The first formula for the calculation of theoretical heating values from the composition of a fuel as
determined from an ultimate analysis is due to Dulong, and this formula, slightly modified, is the
most commonly used to-day. Other formulae have been proposed, some of which are more accurate
for certain specific classes of fuel, but all have their basis in Dulong’s formula, the accepted modified
form of which is:
GCV = 1/100 [8080C + 34500(H2 + O2/8) +2240 S] Kcal/Kg
EXPERIMENTAL DETERMINATION
The higher heating value is experimentally determined in a bomb calorimeter. The combustion of a
stoichiometric mixture of fuel and oxidizer (e.g.,two moles of hydrogen and one mole of oxygen) in a
steel container at 25° is initiated by an ignition device and the reactions allowed completing. When
hydrogen and oxygen react during combustion, water vapor is produced. The vessel and its contents are
then cooled to the original 25°C and the higher heating value is determined as the heat released between
identical initial and final temperatures.
When the lower heating value (LHV) is determined, cooling is stopped at 150°C and the reaction heat is
only partially recovered. The limit of 150°C is an arbitrary choice.
28. Exercises of analysis and calorific value
1.Calculate the gross and net calorific value of a coal which analyses: C 74%, H 6%, N 1%,
O 9%, S 0.8%, moisture 2.2% and ash 8%.
2.The ultimate analysis of a coal(moist basis in %):C 69.8 , H 4.6 , N 1.4, O 8.5, S 2.5, H2O
4.5 and ash 8.7. The gross calorific value, moist basis, is 29920 KJ/Kg. Calculate, by means of the
Dulong formula, the gross calorific value, moist basis, of the coal.
3. The proximate analysis of coal is: Moisture 2.4%, Volatile Matter 29.4%, Fixed Carbon 58%,
Ash 9.7% and Sulphur 0.5%. Its gross calorific value is 7650 Kcal/Kg. Calculate proximate
Analysis and calorific value on
a) Moisture free basis
b) Dry ash free basis
4. A producer gas analyses 50% N2, 25% CO, 18% H2, 6% CO2and 1% O2. Calculate net calorific power
(Kcal/m3
).
5.The ultimate analysis of bituminous coal (dry basis %) is : C 77, H 5.8, N 1.7, O 4.8, S 2.5and
Ash 9. The moisture content is 5 %. The gross calorific power is 7650 Kcal/Kg on dry basis.
Calculate
a) Gross calorific value, moist basis
b) Net calorific value, dry basis
c) Net calorific value, moist basis
d) Gross calorific value, dry basis using Dulong formula.
6. Compare the gross and net calorific value on moist and dry basis of
(a) bituminous coal and
(b) Anthracite coal. The compositions are
29. Kerosene Oil:
Kerosene oil is obtained between 180-250o
C during fractional distillation of crude petroleum.
When kerosene is used in domestic appliances, it is always vaporized before combustion.
By using a fair excess of air it burns with a smokeless blue flame.
USES
Illuminant
Jet engine fuel
Tractor fuel (TVO)
Additives
Gasoline or Petrol:
Gasoline is the most widely used liquid fuel.
Production ofgasoline is achieved by distillation ofcrude oil. The desirable liquid is
separated from the crude oil in refineries.It contains some undesirable unsaturated straight
chain hydrocarbons and sulphur compounds. It has boiling range of40-120o
C.
Liquid gasoline itselfis not actually burned, but its fumes ignite, causing the remaining
liquid to evaporate and then burn. Gasoline is extremely volatile and easily combusts,
making any leakage potentially extremely dangerous.
Classification ofPetroleum:
Paraffinic Base Type Crude Petroleum :
This type ofpetroleum is mainly composed ofthe saturated hydrocarbons from CH4 to C35H72
and a little ofthe napthenes and aromatics. The hydrocarbons from C18H38 to C35H72 are
sometimes called Waxes.
Asphalitc Base Type Crude Petroleum :
It contains mainly cycloparaffins or napthenes with smaller amount ofparffins and aromatic
hydrocarbons.
Mixed Base Type Crude Petroleum :
It contains both paraffinic and asphaltic hydrocarbons and are generally rich in semi-solid
waxes.
30. Properties ofliquid fuels:
Density
• Ratio ofthe fuel’s mass to its volume at 15 o
C,
• kg/m3
• Useful for determining fuel quantity and quality
Viscosity
• Measure offuel’s internal resistance to flow
• Mostimportant characteristic for storage and use
• Decreases as temperature increases
Flash point
• Lowesttemperature at which a fuel can be heated so that the vapour gives off
flashes when an open flame is passesover it
• Flash point of furnace oil: 66o
C
Pour point
• Lowest temperature at which fuel will flow
• Indication of temperature at which fuel can be pumped
Calorific value
• Heat or energy produced
• Gross calorific value (GCV): vapour is fully condensed
• Net calorific value (NCV): water is not fully condensed
Specific gravity
• Ratio ofweight of oil volume to weight ofsame water volume at a given
temperature
• Specific gravity of water is 1
• Hydrometer used to measure
Sulphur content
• Depends on source ofcrude oil and less on the refining process
• Furnace oil: 2-4 % sulphur
• Sulphuric acid causes corrosion
Ash content
• Inorganic material in fuel
• Typically 0.03 - 0.07%
• Corrosion ofburner tips and damage to materials /equipments at high
temperatures
Carbon residue
• Tendency ofoil to deposit a carbonaceous solid residue on a hot surface
• Residual oil: >1% carbon residue
Water content
• Normally low in furnace oil supplied (<1% at refinery)
• Free or emulsified form
• Can damage furnace surface and impact flame
Classification ofgaseous fuel:
31. Producer Gas
Producer gas is a mixture of combustible (Hydrogen, Methane and Carbon Monoxide) and non-
combustible (Nitrogen, Carbon dioxide) gases. The heating value of producer gas varies from 4.5 to 6
MJ/m3
depending upon its constituents. Similar to syngas, producer gas is also produced by gasification
32. of carbonaceous material such as coal or biomass. When atmospheric air is used as gasification agent, the
producer gas consist mostly of carbon monoxide, hydrogen ,nitrogen, carbon dioxide and methane.
What is CalorificValue ?
Calorificvalue (CV) isameasure of heatingpowerand isdependentuponthe compositionof the gas.
The CV referstothe amountof energyreleasedwhenaknownvolume of gasiscompletelycombusted
underspecifiedconditions.
Calorificvalue:
Calorificvalue of fuel isthe total quantityof heatliberatedby completecombustionof aunitmass (or
volume) of the fuel.
It can be expressedforsolidfuelsintermsof :
Cal/g(CGS unit)
Kcal/Kg(MKS)
J/Kg(SI)
B.Th.U/lb (BritishThermal Unit)
