UKAI THERMAL POWER PLANT

Supervisor: Dr. Mohammed Newar

Student Name: Eman Refai Abdel-Khaliq
Section: 3
Department: Mechanical Power
Table of Contents
1. Introduction:................................................................................................................................ 2
2. Cycle General Layout of Ukai thermal power planet: ................................................................ 2
3. Ukai Thermal Power Stations Components: ............................................................................... 4
4. Ukai Thermal Power Stations Specifications:............................................................................. 7
5. LOCATION & APPROACH .................................................................................................... 11
6. CLIMATIC CONDITIONS ...................................................................................................... 11
7. References:................................................................................................................................ 12
 1. Introduction:

The Ukai Thermal Power Station is located near Ukai Dam on Tapi River in Tapi District. It
is a Coal Based Power Station. There are two units of 120 MW each (Unit no. 1 & 2), two
units of 200 MW each (Unit no. 3 & 4) and one unit of 210 MW (Unit no. 5) with a total
installed capacity of 850 MW. All the above units are of BHEL make. Now general layout of
the power plant is given by below.

2. Cycle General Layout of Ukai thermal power planet:

Figure 1 Ukai Cycle Layout

The general layout of the thermal power plant consists of mainly 4 circuits as shown in Fig.1

The four main circuits are:

1. Coal and Ash circuit
2. Air and Gas circuit
3. Feed Water and Steam circuit
4. Cooling Water circuit

A thermal power station using steam as working fluid works basically on the Rankine cycle.
Steam is generated in a boiler, expanded in the prime mover and condensed in condenser and
fed into the boiler again with the help of pump. However, in practice, there are numerous
modifications and improvements in this cycle with the aim of affecting heat economy and to
increase the thermal efficiency of the plant [1].

2.1. Coal and Ash Circuit:

In this circuit, the coal from the storage is fed to the boiler through coal handling equipment
for the generation of steam. Ash produced due to combustion of coal is removed to ash storage
through an ash-handling system [1].

2.2. Air and Gas Circuit:

Air is supplied to the combustion chamber of the boiler either through forced draught or induced draught
fan or by using both. The dust from the air is removed before supplying to the combustion chamber.
The exhaust gases carrying sufficient quantity of heat and ash are passed through the air-heater where
the exhaust heat of the gases is given to the air and then it is passed through the dust collectors where
most of the dust is removed before exhausting the gases to the atmosphere [1].

2.3. Feed Water and Steam Circuit:

The steam generated in the boiler is fed to the steam prime mover to develop the power. The
steam coming out of the prime mover is condensed in the condenser and then fed to the boiler
with the help of pump. The condensate is heated in the feed-heaters using the steam tapped
from different points of the turbine. The feed heaters may be of mixed type or indirect heating
type. Some of the steam and water are lost passing through different components of the system,
therefore, feed water is supplied from external source to compensate this loss. The feed water
supplied from external source to compensate the loss. The feed water supplied from external
source is passed through the purifying plant to reduce to reduce dissolve salts to an acceptable
level. This purification is necessary to avoid the scaling of the boiler tubes [1].

2.4. Cooling Water Circuit:

The quantity of cooling water required to condense the steam is considerably high and it is
taken from a lake, river, or sea. At the Ukai thermal power plant, it is taken from an artificial
lake created near the plant. The water is pumped in by means of pumps and the hot water after
condensing the steam is cooled before sending back into the pond by means of cooling towers.
This is done when there is not adequate natural water available close to the power plant. This
is a closed system where the water goes to the pond and is re circulated back into the power
plant. Generally open systems like rivers are more economical than closed systems [1].

3. Ukai Thermal Power Stations Components:

The salient features of a Ukai Thermal power plant are discussed below:

3.1. Boiler:
In the boiler, the water is converted into steam with the help of heat produced by the burning
of coal. The boiler consists of a tall chimney like structure lined with tubes, which may be as
tall as 40 m. The boiler can be either fire tube or water-tube boiler. The modern big boilers are
all water tube boilers in which water flows through the tubes and the combustion gases flow
across the tubes. A modern boiler may be producing steam at the rate of 375 tonnes/hr at 14
MPa and 540°C and burning coal at the rate of 200 tonnes/hr. The temperature inside the
furnace where fuel is burnt is of the order of 1500°C. The inside of boiler also contains separate
set of tubes which constitute heat exchanges in which heat in the flue gases is exchanged with
other mediums [1]. These are:
3.1.1. Super-heater:
The super-heater is situated at the hottest part of the boiler. It is meant to raise the steam
temperature above the saturation temperature by absorbing heat from flue gases. The maximum
temperature to which steam can be heated will depend upon the metallurgy and economy in
initial cost and maintenance cost of the super-heater. The present trend is to keep the steam
temperature at 540°C. The super-heating of steam makes it possible to recover more energy
from steam which improves the cycle efficiency of the plant. It also eliminates the formation
of water vapours during conveying of steam in pipelines and during its early flow through the
turbine blades. From the super-heater, the steam is led to high-pressure turbine [1].
3.1.2. Reheater:
The function of the reheater is to raise the temperature of steam after it has expanded in the
high-pressure turbine. After being reheated, it passes through the intermediate and low-pressure
turbines. In reheater also, the temperature of steam is limited to 540°C [1].
3.1.3. Economiser:
The function of an economiser in a boiler is to absorb heat from the outgoing flue gases, to
raise the temperature of the feed water coming from the condenser, before it enters the
evaporative section of the boiler. It is usually located ahead of air heaters and following the
super-heater and reheater in the flue gas stream [1].
3.1.4. Air-Heater:
The function of the air-heater in a boiler is to raise the temperature of air with the help of
outgoing flue gases before the air is led to the furnace for the combustion of fuel. The
employment of economiser and air-heater increases the efficiency of the boiler [1].

3.2. Steam Turbine:

The function of a steam turbine is to convert the heat energy in the steam into rotational power
of the shaft on which the turbine is supported. In a modem steam power plant, the steam turbine
is usually a three-cylinder tendum compound machine consisting of one single flow high-
pressure cylinder, one single flow intermediate-pressure cylinder and one double flow low-
pressure cylinder. The rotational speed of the shaft is set by the frequency of the electricity
supply and is 3000 rev./min (50 r/p/s.) corresponding to an alternating electric supply at 50
hertz. The turbine is fitted with a precise oil operated speed governor [1].

3.3. Generator:
The generator, which is directly coupled to the turbine shaft, converts mechanical energy of
turbine shaft into electric energy. It consists of two electrical windings. One is mounted on the
turbine shaft, rotating with it, and is called the rotor. The other is arranged as a shroud around
the rotor, fixed to the floor, and is called the stator. The relative motion of rotor and stator
generates the electricity. The generator which is hydrogen cooled produces electricity at 11,000
volts [1].

3.4. Condenser:
The function of the condenser is to condense the steam which has been discharged from low-
pressure turbine. The condenser is a large vessel containing a large number of brass tubes
through which the cold water is circulated continuously for condensing the steam flowing
outside the surface of the tubes. The hot condensate-flows back to the boiler to be reconverted
into steam. The use of condenser increases the output of the plant by lowering the exhaust
pressure of steam and provides hot feed water for the boiler [1].

3.5. Cooling Towers:

The function of the cooling tower is to cool the hot cooling water coming out of the condenser,
in closed recirculation cooling water system. Here, the hot water is cooled in contact with the
atmospheric air. The air is drawn through the bottom of the cooling tower by induced draft fans
mounted at the top of the cooling tower. (The flow of air upward through the cooling tower can
also be produced either by forced draft fan or it may be natural drought). Whereas the hot
cooling water falls vertically from the top of the cooling tower. The cold cooling water gets
collected in the cooling tower basin and is pumped back through the condenser. The tower may
be made of a metal or of ferro-concrete and may be as tall as a 40-storey building. A cooling
tower may cool 18,000 tonnes of water per hour by 10°C [1].

3.6. Circulating Water Pump:

A circulating water pump circulates cooling water in a closed system comprising of turbine
condenser and cooling tower. Usually, for one unit, two pumps are provided with an additional
circulation water pump acting as a standby for, two units. Each pump circulates more than
about 8000 tonnes of water per hour [1].

3.7. Boiler Feed Pump:

A boiler feed pump is like a heart to the steam power plant. Its aim is to supply feed water
(coming from the condenser) to the boiler at a high pressure. This is one of the most
sophisticated pumps and is the largest auxiliary of the power plant. Usually, for each unit, two
feed pumps are provided [1].

3.8. Wagon Tippler:

The coal may be transported to the plant site by rail wagons. The coal is unloaded at the plant
site mechanically by means of wagon tipplers. The loaded wagon is emptied by tippling it in
the underground coal hopper from where the coal is carried by belt conveyor to the crusher
house (in the case of pulverised fuel firing system). Usually, for each unit, two wagon tipplers
are provided out of which one serves as a standby. Each wagon tippler is capable of tippling 6
to 8 wagons of 55 tonnes each an hour [1].

3.9. Crusher House:

Coal unloaded by wagon tippler is carried to crusher house through conveyors for
crushing. Here, the coal is crushed to a size of 10 mm. The crushed coal is then supplied to
boiler raw coal bunkers. The surplus coal is carried to coal storage area by means of belt
conveyors. Crushing of coal is essential for its optimum pulverising and safe storage [1].

3.10. Coal Mill:

The function of coal mill is to pulverise the raw coal into a fine powder before it is
burnt in the boiler furnace [1].

3.11. Induced Draught (I.D. Fans):

The function of the induced draught fan is to exhaust ash laden flue gases through the interior
of the boiler and dust extracting equipment and to the chimney. The fans are axial flow type
and are driven by an electric motor. Usually, for each unit, two I.D. fans are provided.

3.12. Ash Precipitators:

To avoid air pollution the outgoing flue gases should be freed from dust particles before these
escape into the atmosphere through the chimney. This is done with the help of two precipitators:
Mechanical and electrical. In mechanical precipitators, the coarser ash particles are separated
by centrifugal action. In electrostatic precipitator, which removes finer ash particles, the flue
gas is made to pass through high voltage electric field. The ash particles get ionised and are
attracted towards the collecting electrodes. The ash so separated out of flue gases is collected
in hoppers underneath and further disposed of in ash disposal area [1].

3.13. Boiler Chimney:

The flue gases from the boiler, after removal of the fly ash in the precipitators, are let off to
atmosphere through boiler chimney. It is a tall ferro-concrete structure, lined with fire bricks
for protection of ferro-concrete against hot fuel gases. A protective coating of acid resistance
paint is applied outside on its top 10 meters. The chimney of a modern thermal power plant
maybe as tall as historic Qutab Minar [1].

3.14. Forced Draught Fans (F.D. Fans):

The aim of the forced draught fans is to draw air from the top of the boiler house and pass it
through the air-preheaters, to the hot air duct. From here, some of the air passes directly to the
fuel burners and the remaining is taken through the primary air fan to the pulverising mill,
where it is mixed with the powdered coal, blowing it along pipes to the burners of the furnace
[1].

3.15. Water Treatment Plant:

To avoid any scale formation in boiler tubes and to prevent priming or foaming problems, the
feed water to be used in boilers must be chemically treated in water treatment plant. The daily
make up water supply which may run into hundreds of tones is also produced in water treatment
plant [1].

3.16. Switch Yard:

Electricity generated a 11 kV by the turbogenerator is stepped up by unit transformers to
132/220 kV for further transmission through high tension lines and fed to the regional grid [1].

3.17. Control Room:

The control room is the operational nerve centre of a thermal power station. The performance
of all the plant equipment is constantly monitored here with the help of sophisticated
instrumentation and controllers. Any adverse deviation in the parameters of the various systems
is immediately indicated by visual and audio warning and suitable corrective action is taken,
accordingly. The control room is air-conditioned to maintain the desired temperature for proper
functioning of the instruments [1].

4. Ukai Thermal Power Stations Specifications:

 4.1. Installed Capacity:
Stage I:
Unit 1: 120 MW
Unit 2: 120 MW

Unit 3:
Fuel: Coal - bituminous
Capacity: 200 MW
Technology: Subcritical
Start year: 1979.

Unit 4:
Fuel: Coal - bituminous
Capacity: 200 MW
Technology: Subcritical
Start year: 1979.

Unit 5:
Fuel: Coal - bituminous
Capacity: 210 MW
Technology: Subcritical
Start year: 1985.
Stage II:

Unit 6:
Fuel: Coal - bituminous
Capacity: 500 MW
Technology: Subcritical
Start year: 2013 [2].

4.2. Fuel or heat source:

The primary heat source for the Ukai Thermal Power Station in Gujarat, India is coal
specifically bituminous coal. This power station is a coal-fired thermal power plant, which
means that it uses coal as the fuel to generate heat. Coal is burned in the power plant's boilers,
producing high-pressure steam. This steam is then used to drive turbines, which in turn
generate electrical energy.
The choice of coal as the primary fuel source for the Ukai Thermal Power Station is based on
the availability of coal in the region and its relatively low cost. However, it is important to
note that coal-fired power plants can have significant environmental impacts due to their
emissions of greenhouse gases and air pollutants. Efforts are being made to reduce these
impacts through the use of cleaner coal technologies and the development of alternative
energy sources [3].
In addition to coal, thermal power stations can also utilize other heat sources depending on
availability and specific requirements. These may include fossil fuels such as oil and natural
gas, nuclear power, geothermal energy, solar energy, biofuels, and waste incineration.
However, it is not specified whether the Ukai Thermal Power Station utilizes any other heat
sources in addition to coal.
In case of a shortage of coal, the plant can also run on Light Diesel Oil (LDO) and Heavy
Furnace Oil (HFO) [2].

4.3. Working cycle:

Ukai Thermal Power Station in Gujarat, India utilizes the Rankine cycle. The Rankine cycle
is a thermodynamic cycle that is commonly used in thermal power stations to convert heat
energy into mechanical work and then into electrical energy.
Steam is generated in the boiler of the thermal power plant using heat of the fuel burnt in the
combustion chamber. The steam generated is passed through steam turbine where part of its
thermal energy is converted into mechanical energy which is further used for generating
electric power. The steam coming out of the steam turbine is condensed in the condenser and
the condensate is supplied back to the boiler with the help of the feed pump and the cycle is
repeated. The function of the Boiler is to generate steam. The function of the condenser is to
condense the steam coming out of the low-pressure turbine. The function of the steam turbine
is to convert heat energy into mechanical energy. The function of the condenser is to increase
the pressure of the condensate from the condenser pressure to the boiler pressure. The other
components like economizer, super heater, air heater and feed water heaters are used in the
primary circuit to increase the overall efficiency of the plant[1].
The cycle consists of four phases:

Heat Addition: In this phase, heat is added to the system by burning coal in the power plant's
boilers. This heat is used to convert water into high-pressure steam.

Isentropic Expansion: The high-pressure steam passes through a turbine, where it expands
and loses pressure, thereby producing mechanical work. This work is used to drive the
turbine and generate electricity.
Heat Rejection: After passing through the turbine, the steam is condensed in a condenser,
releasing heat energy. This heat is then rejected to the environment, typically through the use
of cooling towers or a nearby body of water.

Isentropic Compression: The condensed water is then pumped back to the boiler, where it is
heated again to form high-pressure steam, and the cycle repeats [1].

4.4. Efficiency:
As recently reported, the Ukai Thermal Power Station, located in Gujarat, India, had an overall
efficiency of around 33-35% [3].

4.5. Environmental Impact:

The Ukai Thermal Power Station in Gujarat, India, has several environmental impacts due to
its operation as a coal-fired power plant. Coal-based thermal power plants are known to have
significant environmental consequences, including air pollution and greenhouse gas emissions
[4].
Air pollution is a major concern associated with thermal power plants. These power plants emit
various air pollutants, including particulate matter, sulphur dioxide (SO2), nitrogen oxides
(NOx), and carbon dioxide (CO2). These pollutants can have adverse effects on human health
and contribute to the formation of smog and acid rain [3].
Additionally, coal-fired power plants release large amounts of mercury, a toxic heavy metal,
into the environment. This can have detrimental effects on aquatic ecosystems and pose a risk
to human health through the consumption of contaminated fish [3].
Furthermore, thermal power plants require a significant amount of water for cooling purposes.
The withdrawal and discharge of water from rivers, lakes, and reservoirs can impact aquatic
ecosystems by altering water temperatures and reducing water availability for other uses.

Efforts are being made to mitigate the environmental impacts of thermal power plants,
including the Ukai Thermal Power Station. The use of advanced pollution control technologies,
such as electrostatic precipitators and flue gas desulfurization systems, can help reduce
emissions of particulate matter and sulphur dioxide. Additionally, the installation of cooling
towers can minimize the thermal impact on aquatic ecosystems [3].

In recent years, there has been a push towards cleaner and more sustainable sources of energy,
such as renewable energy and energy efficiency measures. These alternatives can help reduce
the reliance on coal-fired power plants and their associated environmental impacts [4].

4.6. Technology:
The power plant operates using subcritical steam turbine technology.
Unit 7, which is currently in the planning stage, will be a supercritical unit[4].

4.7. Unit Status:

Unit 1 and Unit 2 have been retired from service.
Units 3, 4, 5, and 6 are currently operating.
Unit 7 is in the planning stage and has not been commissioned yet [4].

5. LOCATION & APPROACH

1) Existing Project: Total Five units of 120,200 & 210 MW
2) Project: Thermal Power Station Unit#6 (500 MW), Ukai
3) Project location: UKAI, DIST: TAPI, GUJARAT STATE Nearest Railway Station:
SONGARH on the broad gauge, connected from Surat junction on Howrah line. Power
Station is having broad gauge private railway siding served through Rly. Station at distance
of about 10 Kms. ROAD: The site is also connected by roads from SURAT-DHULIA through
highway SH-6 at a distance of 10 Kms from Songarh [4].

6. CLIMATIC CONDITIONS
Maximum temperature: 45℃ Celsius

Minimum temperature: 5℃

Max daily average temp: 35℃

Max yearly average temp: 30℃

Maximum Humidity: 85%
Minimum Relative Humidity: 15%

Average Annual rainfall: 1500𝑚𝑚 (During June -Sep)[3].

7. References:
1. (N.d.). (rep.). REPORT ON INDUSTRIAL VISIT (1st ed., Vol. 1, pp. 3–8).

2. Wikimedia Foundation. (2023, February 28). Ukai Thermal Power Station.

Wikipedia. https://en.wikipedia.org/wiki/Ukai_Thermal_Power_Station

3. Kgi-Admin. (2023, July 30). Power plant profile: Ukai replacement thermal

power station, India. Power Technology. https://www.power-

technology.com/marketdata/power-plant-profile-ukai-replacement-thermal-

power-station-india/

4. Global Energy Monitor. (2023, October 12). Ukai Thermal Power Station.

https://www.gem.wiki/Ukai_Thermal_Power_Station