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BURNING of fossil fuels in commercial and industrial boilers and furnaces results in emissions.
Efficient Burning of
Fuels to Control
Energy Wastage and
Emission
known to cause harmful effects on human beings
and the environment.
Effects on environment and health
The effects of pollutants on the environment and
human health are listed in the table.
Pollutants
By Maznah Abdul Majid
Environmental and Energy Technology Centre
SIRIM Berhad
Carbon
monoxide
Effect on
environment
Toxic gas will make
up
the
air
composition
Introduction
Many industries are burning fossil fuels for their
process heating. Major consumers of fossil fuels
are the steel, cement, metal, petrochemical and
ceramic industries. Burning of fossil fuels in
commercial and industrial boilers and furnaces
results in emissions. The emissions are carbon
dioxide, nitrogen, oxygen, water, carbon monoxide,
nitrogen oxides, sulphur dioxide, volatile organic

Fatal to people
with heart and
lung disease

Cause
headaches and
dizziness in
healthy people
Nitrogen
oxide
Production of ozone
and acid rain
Respiratory
problem
Volatile
organic
compounds
Ozone formation
Mostly cancer
causing chemical
Particulate
matter
Corrosive and toxic
to plants and
animals
Harmful to human
compound and particulate. The later five products
of combustion which are considered pollutants are
Effect on health
Simple rule of combustion
Fuels need oxygen for burning or combustion. In
content will emit more sulphur oxides compared to
fuels with lower sulphur content. These sulphur
most cases, air is used to supply the oxygen
needed. Ideally,
combustion needs the right
oxides can also form sulphates, which contribute to
smoke formation. Ultimate analysis of fuels will
amount of oxygen to get optimum efficiency. Too
give details on the fuel composition.
much air will result in heat loss through the
chimney, too little air wastes fuel and the unburned
Excess air requirement
fuel causes pollution.
Excess air is the extra air supplied to the burner
Fuel choice
beyond the theoretical air required for complete
combustion. Excess air is supplied to the burner
The types of fuel commonly consumed by the
because a boiler firing without sufficient air supply
Malaysian industries are the fuel oil, medium fuel
oil, light fuel oil, diesel, LPG and natural gas. When
is actually operating in a potentially dangerous
condition. Therefore, excess air is supplied to the
purchasing a type of fuel, it is important to check
the composition and the calorific or heating value
burner to provide safety
requirement for combustion.
of the fuel.
The compositions and operating condition of the
combustion
process
will
determine
what
combustion products that will be emitted. The
heating value will determine the heat it liberates
during combustion. The presence of moisture in
fuel will result in a significant loss in energy due to
sensible heat and latent heat loss. The table below
illustrates the variation in heating value depending
on fuel type.
Type
Fuel
Heating
value
Solid
Coal ( depend on grade)
18-33 MJ/kg
Liquid
Gas
Wood waste 30% moisture
12MJ/kg
Dry palm shell
9.2MJ/kg
Coconut shell
20MJ/kg
Fuel oil 180cSt
41.5MJ/kg
Fuel oil
120cSt
42 MJ/kg
Fuel oil
80cSt
43 MJ/kg
Diesel
45MJ/kg
Natural gas
38MJ/kg
One has to be careful in purchasing fuel for their
combustion system. The cost is one of the deciding
factors. Other factors shall include the specification
of fuels. Heating value is important, and so is the
composition of fuel. Fuel with higher sulphur
factor
above
the