LESSON 9 | FUEL CHEMISTRY Flashcards
any combustible substance that contains carbon as a main
constituent, which on proper burning gives a large amount of
useful heat for domestic and industrial purposes
FUEL
During the complete combustion of fuels, carbon is
converted to
hydrogen is converted to
CO2
H2O
the process of oxidation that provides heat energy
Combustion
Every combustion is an oxidation but every oxidation is not combustion.
Combustion
The fuel should be easily available.
TRUE
It should be dry and should have less moisture content. Dry
fuel increases its calorific value.
TRUE
It should be cheap, easily transportable and has high calorific
value.
TRUE
It must have moderate ignition temperature and should
leave less ash after combustion.
TRUE
The combustion speed of a good fuel should be moderate.
TRUE
It should not burn spontaneously to avoid fire hazards.
TRUE
Its handling should be easy and should not give poisonous
gases after combustion.
TRUE
The combustion of a good fuel should not be explosive.
TRUE
Classification of Fuels
occurrence (and preparation)
physical state
found in nature
natural or primary fuels
used either without processing or after being processed to a certain
extent, which does not alter the chemical composition of the fuel
natural or primary fuels
also known as fossil fuels such as wood, peat, lignite, coal, petroleum,
natural gas, etc.
natural or primary fuels
derived from the primary fuels by further processing such as charcoal, coke, kerosene,
producer gas, water gas, etc.
artificial or secondary fuels
The second classification is based on the
physical state.
Type of Fuels
■ 1. Solid fuels
■ 2. Liquid fuels
■ 3. Gaseous fuels
The Philippines had a significant growth in power generation
at 10% from 82,413,213 MW in 2015 to 90,797,891 MW in
2016.
TRUE
The main solid fuels are wood, peat, lignite, coal and charcoal.
Solid Fuels
a fossil fuel which occurs in layers in the earth’s crust
COAL
It is formed by the partial decay of plant and animal materials
accumulated millions of years ago and further altered by action of
heat and pressure.
COAL
Conversion of wood into coal
Wood ⟶Peat ⟶ Lignite ⟶Bituminous Coal ⟶ Anthracite
a brown-fibrous jelly like mas
Peat
soft, brown colored, lowest rank type of coal
LIGNITE
a class of highest rank coa
Anthracite
pitch black to dark grey
Bituminous coal
are the important commercial and domestic
fuels used these days.
Liquid Fuels
Most of these fuels are obtained from the naturally
occurring petroleum or crude oil.
Liquid Fuels
is a dark greenish brown,
viscous oil found deep in the earth crust.
Petroleum or crude oil
is a source of many liquid fuels that are in current use.
Petroleum or crude oil
Approximate composition of crude petroleum
C = 80-85% H = 10-14%
S = 0.1-3.5% N = 0.1-0.5%
obtained from the mine contains a lot of soluble and
insoluble impurities which must be removed
Petroleum or crude oil
Before it is being done by simple
fractional distillation, further treatment is needed by refining.
Purification
a process by which petroleum is made free of impurities
Refining
Stages in the refining of petroleum
■ 1) removal of solid impurities
■ 2) removal of water
■ 3) removal of harmful impurities
■ 4) fractional distillation
decomposition of larger hydrocarbon molecules to smaller
molecules
CRACKING
obtained from the wells dug in the earth during mining
of petroleum
Natural gas
mainly composed of methane and small quantities of
ethane along with other hydrocarbons
Natural gas
lower hydrocarbons are present
Dry gas or lean gas
hydrocarbons having higher molecules are present
Rich or wet gas
calorific value of natural gas
varies from 8000-14000
kcal/m3
.
obtained from natural gas or as a byproduct in refineries
during cracking of heavy petroleum products
LPG (Liquefied Petroleum Gas)
MAIN COMPONENTS OF LPG
n-butane
■ isobutane
■ butylene
■ propane (traces of propene and ethane
contains mainly methane, CH4.
Natural gas
When natural gas is compressed at high pressure
(1000 atm) or cooled to -160oC, it is converted to
CNG (Compressed Natural Gas)
Natural gas being lead or sulfur free, its use
substantially reduces harmful engine emissions.
CNG
defined as the exothermic chemical reaction, which
is accompanied by heat and light
Combustion
the union of an element or a compound with
oxygen
COMBUSTION
the amount of heat required to increase the temperature of 1
gram of water one degree centigrade
calorie
the unit of heat in metric system, and is defined as the quantity
of heat required to raise the temperature of one kilogram of
water one degree centigrade
■ kilocalorie
the unit of heat in English system
■ British thermal unit (B.T.U.)
defined as “the quantity of heat required to increase the temperature of one
pound of water through of one degree of Fahrenheit
■ British thermal unit (B.T.U.)
1 B.T.U. = 252 cal = 0.252 kcal
the quantity of heat required to raise the temperature of one pound of water
one degree centigrade
Centigrade heat unit (C.H.U.)
1 kcal = 3.968 B.T.U. = 2.2 C.H.U.
