1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME
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INVESTIGATION AND ANALYSIS OF AIR POLLUTION EMITTED FROM
THERMAL POWER PLANTS: A CRITICAL REVIEW
S. Paliwala
, H.Chandrab
and A. Tripathic
a
Department Of Mechanical Engineering, Sunderdeep College of Engineering & Technology,
Ghaziabad (Research Scholar, Singhania University)
b
Department Of Mechanical Engineering , Bhilai Institute of Technology, Durg-491001 (CG) India
c
Jaypee University of Engineering and Technology, Guna- 473226 (M.P.) India
ABSTRACT
A critical review of air pollution emitted from thermal power plants has been carried out by
considering several literatures. It is concluded that the disposal of fly ash generated in thermal power
plants poses a problem, as it required a large amount of land for dumping, however if utilized
properly, this may turn into a resource material for number of sectors for Indian economy. Also it is
found that biomass fired power plant using rice husk and cotton stalk as fuel has much lower
efficiency than coal based power plant. Therefore, there is need to improvement in overall efficiency
of biomass fired thermal power plant by proper improvement in the design DF boiler, heat transfer
surfaces, fuel field systems, combustion equipment and by improving the fuel qualities, in order to
give sufficient rise in overall efficiency of plant.
1. INTRODUCTION
In India approximately 70% of power generation is obtained via thermal power plants. In
India oil/gas reserves are not much, though India has abundant coal reserves, (with high ash content)
which are expected to last nearly 200 years at the present consumption rate (1). So almost all the
thermal power plants were using lump of coal in their boilers and were disposing of coal residue as
bottom ash commonly known as furnace clinker (or cinder), coal breeze or ash, depending upon the
extent of combustion it had undergone and its granulometry. The quality of fuel used for combustion
in furnace of boiler is responsible for the energy efficiency and environmental pollution of thermal
power plant. However the coal found in different coalfields of India is characterized by low calorific
value and high ash content [31]. So, for getting a unit amount of electricity, large amount of
pollutants are generated. It is desirable to have a good quality of coal for power generation, as it
reduces the pollutants generated/unit of electricity. Out of different air pollutants, ash is mineral
matter present in the fuel. For a pulverized coal unit 60-80 % of ash leaves as fly ash with the flue
gases. Though there are several devices for collection of fly ash, the two efficient (≥ 99 % collection
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2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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efficiency) emission control devices are fabric filters and Electrostatic Precipitator (ESPs) [42].
Fabric filters have low installation cost but high maintenance cost; and large pressure drop, which
reduce the plant efficiency. The ESP is one of the most widely used devices for controlling
particulate matter especially fly ash. Although they often demand higher capital investment in
comparison with gas cleaning methods, the low operating cost and maintenance costs, the high
collection efficiency (> 99%) & the ability to face severe operating conditions make ESPs suitable in
the pollution problems characterizing many processes installations such as coal-based thermal power
plants, cement plants, iron industries and glass manufacture [39, 26, 28, 37, 6, 22,8].
In this paper a detailed literature survey is performed to get the types of pollutants emitted from
conventional as well as cogeneration power plants and methodology to reduce the harmful pollutants.
2. POLLUTIONS EMITTED FROM CONVENTIONAL POWER PLANTS
Due to abundant coal reserves in India, coal based thermal power plants exist in large
numbers and new plants are being proposed to meet future energy demands. Burning of fossil fuels,
especially coal causes considerable air pollution. Since the amounts of air pollutants emitted are
usually above the given national and international recommendations and standard, thermal power
plants should be equipped with suitable pollution control devices. Since the power demand is
growing and also power plants are shifted towards their centers of demand in urban areas, the
evaluation of environmental impact from such plants is becoming more and more important.
Environmental Impact Assessment (EIA) is the official appraisal of the likely effects of a proposed
policy, program, or project on the environment; alternatives to the proposal; and measures to be
adopted to protect the environment. The primary purpose of the EIA process is to encourage the
consideration of the environment in planning and decision making and ultimately to arrive at actions,
which are more environmentally compatible [33, 5, 34, 32, 22, 10].
Electric power plays a crucial role in the economic development of a country. So it is worth
to investigate the economics of thermal power plant. For the study of economies the estimates
relating to investment cost, energy cost or real costs per MWh capacity for the sets functioning in the
Indian thermal power stations are required. Such estimates are not available, so we have to compute
them from cost function for these sets, with cost being dependent on capacity of power plant [31, 35
and 36]. In thermal power plants the cost associated due to environment is also significant factor in
the analysis of economics, which is due to the pollution control equipments used in the thermal
power plants [29].
[21] Performed analysis for effects of thermal power plants on atmospheric electrical
parameters and Observations of the surface atmospheric electric field, point discharge current and
wind in the vicinity of a thermal power plant were made during three field observational
programmes. Results of these observations are presented and they are used for determining the
minimum distance from the source point for expecting normal fair weather surface atmospheric
electric field. Measurements of surface atmospheric electric field may be considered as one of the
aids for the detection of pollution caused by industrial processes. SO2 is a major constituent in air
pollution and affects the environment by no. of ways like acid rain, corrosions and severe damage to
the health. SO2 causes a wide variety of health and environmental impacts because of the way it
reacts with other substances in the air. Particularly sensitive groups include people with asthma who
are active outdoors and children, the elderly, and people with heart or lung disease. Intensity of SO2
emission can be observed by following example. A typical 6 MW power generation unit using
furnace oil containing 2 % Sulphur will emit 388 tons of SO2 per year, based upon 320 working days
or A 22.5 MW power generation unit will emit 1690 tons of SO2 per year by using Pet Coke [4, 15].
[41] Presents a technique to study air pollution by combining high spatial resolution data
obtained by a mobile platform and those measured by conventional stationary stations. Conventional
stations provide time-series point data but cannot yield information that is distant from the sites. This

3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME
34
can be complemented or supplemented by mobile measurements in the vicinity of the conventional
sites. Together, the combined dataset yields a clearer and more precise picture of the dispersion and
the transformation of pollutants in the atmosphere in a fixed time frame. Several experiments were
conducted in the years 2002-2003 to track the impact of power plant plumes on ground receptors in
the immediate vicinity (within a radius of 30 km) of the plants, using a combined mobile and
stationary dataset.
[12], studied the evolution of aerosol emissions from coal-fired power plants due to
coagulation, condensation, and gravitational settling and health impact and found that the scavenging
efficiencies of aerosol emissions from coal-fired power plants under different removal mechanisms
(coagulation, heterogeneous nucleation and gravitational settling) as a function of time. It also
analyses the 'health impact' of the aerosol before and after the above dynamic mechanisms by
comparing the respirable dust fractions. [1] Concluded in their research that solid waste (flyash) [11]
has attained an apparent scenario for scientific & strategic concern in India due to large-scale
dependence on coal-based thermal power plants. Waste utilization as the best option of pollution-
prevention and disaster risk strategy has been worked out during previous decades to open doors for
flyash utilization on various sectors of developmental and manufacturing sectors. [38] explored the
environmental challenges faced by Indian thermal power industries and found that top management
commitment and support; training and awareness of internal people, unacquainted society, and poor
legislation are the few important challenges for effective implementation of environmental
management practices in Indian power industries.
3. POLLUTIONS EMITTED FROM COGENERATION POWER PLANTS
[27] Performed thermodynamic and economic analysis of 1.4 MWe Rice Husk fired
cogeneration in Thailand and found that the rice husk-match cogeneration is more economically
feasible than the thermal-match cogeneration. The capacity of back pressure steam-fired boiler is 18
tons/hour of steam at 25 bar (absolute) and 400oC. The rice husk-match cogeneration can generate
power of 1,432 kW while the thermal-match cogeneration can produce power only 923 kW. The
economic analyses in terms of the net present value (NPV), simple pay-back period (PBP), and
internal rate of return (IRR) are also evaluated. Results show that the rice husk-match cogeneration
has NPV of 0.30 million US$/year, PBP of 3.7 years and IRR of 27%, while the thermal-match
cogeneration has NPV of 0.18 million US$/year, PBP of 5.5 years and IRR of 17%.
Rice husk is one of the most widely available agricultural wastes in many rice producing
countries around the world. Globally, approximately 600 million tons of rice paddy is produced each
year. On average 20% of the rice paddy is husk, giving an annual total production of 120 million
tones. In majority of rice producing countries much of the husk produced from processing of rice is
either burnt or dumped as waste. Burning of RH in ambient atmosphere leaves a residue, called rice
husk ash. For every 1000 kgs of paddy milled , about 220 kgs ( 22 % ) of husk is produced, and
when this husk is burnt in the boilers , about 55 kgs ( 25 % ) of RHA is generated [14, 18, 30, 2, 24,
3].
[9] performed a case study and found that Rice husk is a potential source of energy for an
agricultural country like Thailand with high rice production. Rice mills can use the rice husk
generated by them as a fuel to produce energy. However, the environmental profile of the energy
production must be assessed to ensure reduced environmental damage. This study has been carried
out at the Roi Et Green Project which is a pilot project of capacity 9.8 MW using rice husk as the
feedstock. The power plant uses 290 tons of rice husk and 1,400 tons of water in one day, and has a
power requirement of 1 MW. Net power output is 8.8 MW, which will be sold to Electricity
Generation Authority of Thailand (EGAT) for 21 years under the small power producer (SPP)
scheme. The raw materials consumed and environmental emissions of energy production from rice
husk are determined. The study shows that the emissions of SO2 and NOX are lesser in case of coal

4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME
35
and oil-fired power generation, but higher than for natural gas. The emission of CO2 from
combustion of rice husk are considered zero since they do not contribute to global warming.
[25] checked the feasibility of feasibility of installing rice husk power plant in Chhattisgarh to
meet sustainable energy demands and found that, the use of rice husk for electricity generation in
efficient manner in Chhattisgarh is likely to transform this agricultural by product or waste into a
valuable fuel for industries and thus might help in boosting the farm economy and rural development
of this newly developed state. In fact a systematic approach to this material can give birth to a new
industrial sector of rice husk power production in India.
Coal is used widely as a thermal energy source in thermal power plant for production of
electricity but available coal in India is of poor quality, with very high ash content and low calorific
value. Utilization of huge amount of coal in thermal power plant has created several adverse effects
on environment leading to global climate change and fly ash management problem. Coal based
thermal power plants all over the world is cited to be one of the major sources of pollution affecting
the general aesthetics of environment in terms of land use, health hazards and air, soil and water in
particular and thus leads to environmental dangers. So, the disposable management of fly ash from
thermal power plant is necessary to protect our environment. It is advisable to explore all possible
application for fly ash utilization. Several efforts are needed to utilize fly ash for making bricks, in
manufacture of cement, ceramics etc. Various governmental and nongovernment bodies working in
the field of utilization of fly ash for construction of road/road embankment. The utilization of fly ash
gives good result in almost every aspects including good strength, economically feasible and
environmental friendly [17, 16, 11, 19, 20].
[13] and [23] found in their research that measurements of CO2 (direct GHG) and CO, SO2, NO
(indirect GHGs) were conducted on-line at some of the coal-based thermal power plant in India. The
objective of the study having three major objectives: to quantify the measured emissions in terms of
emission coefficient per kg of coal and per kWh of electricity, to calculate the total possible emission
from Indian thermal power plant, and subsequently to compare them with some previous studies.
Instrument IMR 2800A Flue Gas Analyzer was used on-line to measure the emission rates of CO2,
CO, SO2, and NO at 08 numbers of generating units of different ratings. Certain quality assurance
(QA) and quality control (QC) techniques were also adopted to gather the data so as to avoid any
ambiguity in subsequent data interpretation. For the betterment of data interpretation, the requisite
statistical parameters (standard deviation and arithmetic mean) for the measured emissions have been
also calculated.
4. CONCLUSIONS
1. The disposal of fly ash generated in thermal power plants poses a problem, as it required a large
amount of land for dumping, however if utilized properly, this may turn into a resource material
for number of sectors for Indian economy.
2. To meet the better emission standards the size of ESPs should be increased which is costly affair.
A cheaper option is to adapt micro processor controller charging system which will enhance the
migration velocity and hence met the emission standards. The cost of such device will be much
cheaper as compared to increase the size of ESP.
3. Proper action should be taken for improvement in clear power generation technology, for this
purpose there should look on renewable energy source. In power generation biomass is one of
best renewable energy source.
4. Biomass fired power plant using rice husk and cotton stalk as fuel has been also considered, these
plants are having much lower efficiency than coal based power plant. Therefore, there is need to
improvement in overall efficiency of biomass fired thermal power plant by proper improvement
in the design DF boiler, heat transfer surfaces, fuel field systems, combustion equipment and by
improving the fuel qualities, in order to give sufficient rise in overall efficiency of plant.

5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 4, July - August (2013) © IAEME
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