This PPT contains introduction and types of thermal power plants, WORKING PRINCIPLE, LAYOUT AND WORKING OF NUCLEAR POWER PLANT, WORKING PRINCIPLE OF COAL BASED POWER PLANT, SITE SELECTION OF THERMAL POWER PLANT,GENERAL LAYOUT AND WORKING OF COAL BASED THERMAL POWER PLANT, PRESENT STATUS OF COAL-FIRED THERMAL POWER PLANT, WASTE GENERATED IN THERMAL POWER PLANTS AND MANAGEMENT , TREATMENT AND DISPOSAL OF WASTE GENERATED IN THERMAL POWER PLANTS.

1. THERMAL POWER PLANT
ANISH KUMAR GUPTA
40420705615
Environmental Engineering
3rd Year
Industrial Waste Management

2. Introduction
 In Thermal Power Plants heat energy is converted to mechanical energy
further this mechanical energy is used to generate electricity.
 Thermal power plants is based on Rankine Cycle for electricity production.
Water is heated, turns into steam and spins a steam turbine which drives an
electrical generator. After it passes through the turbine, the steam is
condensed in a condenser and recycled to where it was heated, this is known
as a Rankine Cycle.
 Almost all coal, petroleum, nuclear, geothermal, solar thermal electric, and
waste incineration plants, as well as many natural gas power stations are
thermal.
 In India 65% of total power is generated by the Thermal Power Stations.

3. WORKING PRINCIPLE OF NUCLEAR POWER
PLANT
 A nuclear power plant is a thermal power plant.
The difference between the two is in the fuel they
use to heat the water in the boiler(steam
generator).
 Inside a nuclear power station, energy is released
by nuclear fission in the core of the reactor.
 Uranium atoms make heat by splitting uranium
atoms – the technical term is fission.
 1 kg of Uranium U235 can produce as much
energy as the burning of 4500 tonnes of high grade
variety of coal or 2000 tonnes of oil.

4. LAYOUT OF NUCLEAR POWER PLANTS

5. WORKING OF NUCLEAR POWER PLANT
 In nuclear plants nothing is burnt to create steam. Instead, they split uranium
atoms in a process called fission.
 As a result, nuclear power plants do not release carbon or pollutants like
nitrogen and sulfur oxides into the air.
 Nuclear reactors are designed to sustain an ongoing chain reaction of fission;
they are filled with a specially designed, solid uranium fuel and surrounded by
water, which facilitates the process.

6.  When the reactor starts, U235 atoms will split, releasing neutrons and heat.
Those neutrons will hit other uranium atoms causing them to split and
continue the process, generating more neutrons and more heat.
 This heat is used to create the steam that will spin a turbine, which powers a
generator to make electricity.

7. WORKING PRINCIPLE OF COAL
BASED POWER PLANT
 Firstly the water is taken into the boiler from a water source. The boiler is
heated with the help of coal.
 The increase in temperature helps in the transformation of water into
steam. The steam generated in the boiler is sent through a steam turbine.
 The turbine has blades that rotate when high velocity steam flows across
them. This rotation of turbine blades is used to generate electricity.
 A generator is connected to the steam turbine. When the turbine turns,
electricity is generated and given as output by the generator, which is
then supplied to the consumers through high-voltage power lines.

8. SITE SELECTION OF THERMAL POWER PLANT
The following list corers most of the factors that should be studied and
considered in selection of proper sites for power plant construction:
 Transportation Network: Easy and enough access to transportation network is
required in both power plant construction and operation periods.
 Gas pipe Network: Vicinity to the gas pipes reduces the required expenses.
 Transmission Network Power : To transfer the generated electricity to the
consumers, the plant network can play a roll.
 Geology and Soil Type: The power plant should be built in an area with soil
and rock layers that could stand the weight and vibrations of the power plant.

9.  Earthquake and Geological Faults: Even weak & small earthquakes can
damage many parts of a power plant intensively. Therefore the site should be
away enough from the faults and previous earthquake areas.
 Rivers and Floodways: obviously, the power plant should have a reasonable
distance from permanent and seasonal rivers and floodways.
 Water Resources: For the construction and operating of power plant different
volumes of water are required. This could be supplied from either rivers or
underground water resources.
 Environmental Resources: Operation of a power plant has important impacts
on environment. Therefore, priority will be given to the locations that are far
enough from national parks, wildlife, protected areas, etc.
 Population Centers: For the same reasons as above, the site should have an
enough distance from population centers.

10. GENERAL LAYOUT OF THERMAL
POWER PLANT

11. F.D. Fan – Forced Draft Fan (used to force air into the boiler).
I.D. Fan - Induced Draft Fan (used to extract the air from boiler via Electrostatic Precipitator to exhaust).
P.A. Fan - Primary air fan (used to transport the pulverized coal from mills to the furnace area).

12. MAIN PARTS OF THERMAL POWER PLANT
 Coal Conveyer: With this coal is transported from to the place nearby boiler.
 Stoker: Stoker is a mechanical device for feeding coal to a furnace.
 Pulverizer: It is a device for grinding coal for combustion in a furnace in a power
plant.
 Boiler:- Pulverized coal is put in boiler furnace. It is an enclosed vessel in which water
is heated & circulated until the water is turned in to steam at the required pressure.
 Super heater: It is a component of a steam-generating unit in which steam, after it has
left the boiler drum, is heated above its saturation temperature.

13.  Condenser: Steam after rotating steam turbine comes to condenser. It converts
steam from its gaseous to its liquid state.
 Cooling Towers : The condensate formed after condensation is initially at
high temperature. This hot water is passed to cooling towers and gets cooled.
 Economizer: Function of economizer is to recover some of the heat from the
heat carried away in the flue gases up the chimney and utilize for heating the
feed water to the boiler.
 Air preheater: The remaining heat of flue gases is utilized by air preheater. It
is a device used in steam boilers to transfer heat from the flue gases to the
combustion air before the air enters the furnace.
 Electrostatic Precipitator: It is a device which removes dust or other finely
divided particles from flue gases by charging the particles then attracting them
to highly charged collector plates.

14.  Smoke Stack (Chimney): A chimney is a
system for venting hot flue gases or smoke
from a boiler, furnace or fireplace to the
outside atmosphere.
 Generator: An alternator is an
electromechanical device that converts
mechanical energy to alternating current
electrical energy.
 Transformers: It is a device which increases
or reduces the voltage. Uses for
transformers include reducing the line
voltage to operate low-voltage devices &
raising the voltage from electric generators
so that electric power can be transmitted
over long distances.

15. WORKING OF THERMAL POWER PLANT
 Working process for Thermal Power Plant is as given below:
1) Coal is conveyed with the help of Coal Conveyer from an external stack and
ground to a very fine powder by large metal spheres in the pulverized fuel mill.
2) There it is mixed with preheated air driven by the Forced draught fan.
3) The hot air-fuel mixture is forced at High pressure into the Boiler where it
rapidly ignites.
4) Water of a high purity flows vertically up the tube-lined walls of the boiler,
where it turns into steam, and is passed to the boiler drum, where steam is
separated from any remaining water.

16. 5) The steam passes through a manifold in the roof of the drum into the
pendant Super heater where its temperature and pressure increase rapidly to
around 200 bar and 570°C, sufficient to make the tube walls glow a dull red.
6) The steam is piped to the High-pressure turbine, the first of a three-stage
turbine process.
7) A Steam governor valve allows for both manual control of the turbine and
automatic set point following.
8) The steam is exhausted from the high-pressure turbine, and reduced in both
pressure and temperature, is returned to the boiler Reheater.
9) The reheated steam is then passed to the Intermediate pressure turbine, and
from there passed directly to the low pressure turbine set.

17. 10) The exiting steam, now a little above its boiling point, is brought into
thermal contact with cold water (pumped in, from the cooling tower) in the
Condenser, where it condenses rapidly back into water, creating near vacuum-
like conditions inside the condenser chest.
11) The condensed water is then passed by a feed pump through a Deaerator, &
prewarmed, first in a feed heater powered by steam drawn from the high
pressure set, & then in the Economizer, before being returned to the boiler drum.
12) The cooling water from the condenser is sprayed inside a Cooling tower,
creating a highly visible plume of water vapor, before being pumped back to the
Condenser in cooling water cycle.

18.  13) The 3 turbine sets are coupled on the same shaft as the 3-phase
electrical generator which generates an intermediate level voltage
(typically 20-25 kV).
 14) This is stepped up by the unit Transformer to a voltage more suitable
for transmission (typically250-500 kV) and is sent out onto the 3-phase
Transmission System.
 15) Exhaust gas from the boiler is drawn by the Induced draft fan through
an Electrostatic Precipitator & is then vented through the Chimney stack.

19. PRESENT STATUS OF COAL-FIRED THERMAL
POWER PLANT
Source: IEA 2008
*other includes solar, wind, combustible renewables, geothermal & waste.

20. WASTE GENERATED IN THERMAL
POWER PLANTS

21.  Coal-based thermal power plants are one of largest emitters of elemental mercury.
 Indian coal-based power plants release around 63 tonnes of mercury every year.
 Main emissions from coal fired and lignite based thermal power plants are CO2,
NOx, SOx, and air-borne inorganic particles such as fly ash, carbonaceous
material (soot), suspended particulate matter (SPM), and other trace gas species.
 A typical 500 MW thermal power plant using coal emits around 105 tonne per day
(tpd) of SO2, 24 tpd of NO2 and 2.5 tpd of particulate matter and ash around
3,000-3,500 tpd. Moreover, disposing one tonne of fly ash requires around 1 sq. m
of land.
 It is also the largest emitter of carbon dioxide, a greenhouse gas.
source: Down To Earth
Magazine.

22.  Wastes generated in nuclear power plant contains 95% of the radioactive
material.
 Wastes generated in nuclear power plants are:
i) Low-level waste: It has a radioactive content. It comprises paper, rags,
tools, clothing, filters, etc., which contain small amounts of mostly short-
lived radioactivity.
ii) Intermediate-level waste: Intermediate-level waste (ILW) is more
radioactive than LLW, but the heat it generates is not sufficient for the
storage and disposal facilities. Due to its higher levels of radioactivity,
ILW requires some shielding.

23. • ILW typically comprises chemical sludges, and metal fuel cladding, as well
as contaminated materials from reactor decommissioning. It makes up some
7% of the volume and has 4% of the radioactivity of all radioactive waste.
iii) High-level waste: HLW arises after the fission of uranium fuel in a
. nuclear reactor.
High-level waste (HLW) is sufficiently radioactive.
HLW accounts for just 3% of the volume, but 95%
. of wastes are radioactive.
iv) Very low-level waste: very low-level waste (VLLW) contains
radioactive materials at a level which is not considered harmful to people or the
surrounding environment.
It consists mainly of demolished material (such as concrete, plaster, bricks,
metal, valves, piping, etc.) produced during dismantling operations on nuclear
industrial sites.

24.  Wastes from the petroleum based thermal power plants, waste incineration
plants, and many natural gas power stations includes, CO2, NOX, SOx, etc.
 Open-loop systems of geothermal power plants do not contain the water and
steam as well. As a result, carbon dioxide, methane, boron, hydrogen sulfide,
ammonia, and other gases are emitted into the atmosphere
 Water from geothermal reservoirs contains some chemicals that are toxic to
human health like arsenic, mercury and selenium. The waste products
produced by the geothermal power plants is known as brine.
 This is the water that has been pulled up and contains some harmful metals and
minerals. These includes corrosive salts, silica, gold, silver, platinum and
hydrogen sulfide.

25. MANAGEMENT , TREATMENT AND
DISPOSAL OF WASTE GENERATED IN
THERMAL POWER PLANTS

26. Particulate Control
 It is controlled by the use Electrostatic
Precipitators or Fabric Filters. Electrostatic
Precipitators have 99.9% efficiency for the
removal of particulate matter.
 An electrostatic precipitator is an device that
removes dust particles from a flowing gas
using the force of an induced electrostatic
attraction (i.e., like charges repel; unlike
charges attract).
 ESPs are highly efficient filtration devices
that allow the flow of gases through the
device, and can easily remove fine particulate
matter such as dust and smoke from the air
stream.

27. SOx CONTROL
 A variety of SO2 removal technologies are available. These include wet FGD,
dry FGD utilizing a Spray Dryer Absorber (SDA), Circulating Dry Scrubber
(CDS), and Dry Sorbent Injection (DSI).
 Limestone is commonly used as the reagent for wet FGD. For most high sulfur
applications, a limestone wet FGD has an overall lower cost than other
processes for SO2 removal.
 Wet FGDs have been successfully used for a complete range of coal types
including anthracite, bituminous, sub-bituminous, lignite and brown coals.
 Wet FGD is also installed on systems that use heavy oil and Orimulsion for
fuel. Conventional wet FGD systems utilize a wet limestone process with in
situ forced oxidation to remove SO2 and produce a gypsum byproduct. The
overall reaction is:
CaCO3 + SO2 + 1/2 O2 + 2H2O →CaSO4 • 2H2O + CO2

28.  The SO2 removal process begins as hot flue gas enters the absorber tower
where it is cooled and saturated by the slurry.
 The flue gas then flows upward through the absorber spray zone, where slurry
is sprayed countercurrent to the flue gas flow, completing the SO2 removal
process.
 Typically, the SO2 removal process includes an in situ forced oxidation system
which converts calcium sulfite (CaSO3 • ½H2O) formed by the SO2 removal
process to calcium sulfate (CaSO4 • 2H2O) or gypsum.

29. NOx CONTROL
 The final step is to use post-combustion NOx
control such as selective non-catalytic
reduction (SNCR) or selective catalytic
reduction (SCR) systems if the targeted NOx
removal cannot be achieved.
 NOx is reduced to nitrogen (N2) and water
(H2O) through a series of reactions with a
chemical reagent injected into the flue gas.
 The catalyst is consists of Platinum and
Palladium.

30.  Ash produced is stored on a large are far away from the human population.
The barren land are used for its storage.
 Ash are also used to make bricks which are used in the construction of
Flyovers. For example, ash produced by NTPC Badarpur plant (coal based
thermal power plant) is used the in the construction of Badarpur Flyovers.
 After the use of U235 in nuclear plants, these are disposed off into the deep
sea, in a box of Lead. Because lead blocks act as shield for the radioactive
material.
 Nuclear waste cannot be REUSE, REDUCE or RECYCLE.
MANAGEMENT OF ASH AND DISPOSAL
NUCLEAR WASTE

31. Mercury Control
 Powdered activated carbon (PAC) injected into the flue gas is the most
established technology for mercury control, and can provide up to approximately
95% mercury capture for coals.
 By adsorbing onto the surface of the PAC, the elemental, oxidized mercury and
particulate mercury are removed in particulate control devices (ESP or fabric
filter).
 Fly ash is made of mainly silica (48.27%), and aluminum oxide (30.89%), it can be
converted into zeolites. Zeolites are stable and porous mineral solids that have
qualities that make them exceptional as well as incredibly useful.
 Zeolite minerals form naturally, but can also be made artificially from fly ash.
They have very high stability at high temperature and high pressures, they don’t
burn, don’t dissolve in water or organic solvents, and don’t oxidize in the air.

32. THANK YOU!