UNIT-I
HYDROELECTRIC & THERMAL POWER STATIONS
1 (a) What are the functions of surge tank in hydro plants?
Surge tank is a small storage tank or reservoir required in the hydro power plants for regulating the
water flow during load reduction and sudden increase in the load on the hydro generator and thus
reducing the pressure on the penstock. When the load on the generator is reduced suddenly (load
throw-off), governor closes the turbine gates and thus create an increase in pressure on the penstock.
This may result in water " hammering effect" and may require pipe of extra ordinary strength for
this pressure, otherwise the penstock may burst. To avoid this positive water hammering pressure
some means are provided to take the rejected flow of water.
1 (b) What is meant by the phenomenon “water hammer”?
In a hydroelectric power plant, water hammer refers to the sudden pressure surge that occurs in
penstocks (large pipes carrying water to the turbines) when there is an abrupt change in water flow.
This typically happens due to the rapid closure or opening of turbine gates or valves, or sudden load
rejection by the generator.
Causes of Water Hammer in Hydroelectric Power Plants
1. Sudden Closure of Turbine Gates
2. Load Rejection by Generator
3. Rapid Opening of Valves
1 (c) What is the Thermal Efficiency of Steam Power Plant?
The thermal efficiency of a steam power plant is a measure of how effectively the plant converts the
energy in fuel (such as coal, natural gas, or oil) into useful work (electricity). It is defined as the
ratio of net work output (electricity generated) to heat energy input (fuel energy supplied).
1 (d) What is the Pulverization and write its advantages in thermal power station.
Pulverization in a thermal power station refers to the process of crushing and grinding coal into a
fine powder before it is burned in the boiler. This is done using mills to ensure better combustion
efficiency and higher energy output. The pulverized coal is then mixed with air and blown into the
, boiler for combustion.
Advantages of Pulverization in Thermal Power Stations:
1. Improved Combustion Efficiency
2. Faster and Stable Ignition
3. Higher Thermal Efficiency
4. Reduced Fuel Consumption
1 (e) What are different Types Steam Boilers used In Thermal Power Plants?
Steam boilers in thermal power plants generate steam by heating water using fuels such as coal.
Steam boilers are classified based on various parameters like water circulation, pressure, and design.
Based on Water Flow Configuration:
(a) Fire-Tube Boiler
• Hot gases pass through tubes surrounded by water. This type of boilers are suitable for small
power plants with low pressure and steam demand.
(b) Water-Tube Boiler (Common in Power Plants)
Water flows inside tubes, and hot gases surround them. This type of boilers handles high pressure
and temperature, making it ideal for large power plants.
2 (a) What is a steam power station? Discuss its advantages and disadvantages.
A steam power station, also known as a thermal power station, is a facility that converts heat energy
into electrical energy using steam. In steam power plant, where water is heated in a boiler to
produce steam. This high-pressure steam is then directed onto the blades of a steam turbine, causing
it to spin. The turbine is connected to a generator, which produces electricity.
2 (b) What are the factors considered, while selecting the site for a thermal power station?
Selection of the site for a thermal power station:
,3 Draw and explain the general layout of hydroelectric power plant?
The schematic arrangement of a hydroelectric power plant is shown in figure.
Following are the essential components of the hydro-power plant:
1. Catchment area
2. Reservoir
3. Dam
4. Spillways
5. Penstock
6. Surge tank
7. Prime mover
, 8. Draft tubes
9. Powerhouse and equipment.
Catchment Area
The whole area behind the dam draining into a stream or river across which the dam has been built
at a suitable place is called the catchment area.
Reservoir:
It is the area where the water is stored and utilized for power generation. A reservoir may be natural
or artificial. A natural reservoir is a lake in high mountains. An artificial tank is built by erecting a
dam across the river.
Dam
A dam is a barrier built across the river to store the water for power generation. Dams are built of
concrete or stone masonry, earth, or rockfill. The dam stores the water on one side and on the other
side, it is having a powerhouse to generate the power.
Spill Ways
It is a safety valve for a dam. It is provided to discharge the excess water from the dam to safeguard
the dam against floods.
Penstock
It is a pipe connected between the surge tank and prime mover, usually, these are of steel-reinforced
concrete pipes.
Surge Tank
There is a sudden increase in pressure in the penstock due to the sudden decrease in the rate of water
flow to the turbine when the gates admitting water to the turbines are suddenly closed owing to the
action of the governor. This happens when the load on the generator decreases. This sudden rise of
pressure in the penstock above normal due to reduced load on the generator is known as the “water
hammer”. A surge tank is a small reservoir employed between the dam and the powerhouse nearer
to the powerhouse to reduce the pressure swings in the penstock by allowing the excess water to
enter into the surge tank during low load periods and the stored water can be supplied to the
penstock during high load periods.
Prime Mover
These are the turbines used to convert the kinetic energy of the water into mechanical energy to
produce electric energy.
Draft Tube
It is a diverging discharge passage connected to the tailrace. It supports the runner in utilizing the
HYDROELECTRIC & THERMAL POWER STATIONS
1 (a) What are the functions of surge tank in hydro plants?
Surge tank is a small storage tank or reservoir required in the hydro power plants for regulating the
water flow during load reduction and sudden increase in the load on the hydro generator and thus
reducing the pressure on the penstock. When the load on the generator is reduced suddenly (load
throw-off), governor closes the turbine gates and thus create an increase in pressure on the penstock.
This may result in water " hammering effect" and may require pipe of extra ordinary strength for
this pressure, otherwise the penstock may burst. To avoid this positive water hammering pressure
some means are provided to take the rejected flow of water.
1 (b) What is meant by the phenomenon “water hammer”?
In a hydroelectric power plant, water hammer refers to the sudden pressure surge that occurs in
penstocks (large pipes carrying water to the turbines) when there is an abrupt change in water flow.
This typically happens due to the rapid closure or opening of turbine gates or valves, or sudden load
rejection by the generator.
Causes of Water Hammer in Hydroelectric Power Plants
1. Sudden Closure of Turbine Gates
2. Load Rejection by Generator
3. Rapid Opening of Valves
1 (c) What is the Thermal Efficiency of Steam Power Plant?
The thermal efficiency of a steam power plant is a measure of how effectively the plant converts the
energy in fuel (such as coal, natural gas, or oil) into useful work (electricity). It is defined as the
ratio of net work output (electricity generated) to heat energy input (fuel energy supplied).
1 (d) What is the Pulverization and write its advantages in thermal power station.
Pulverization in a thermal power station refers to the process of crushing and grinding coal into a
fine powder before it is burned in the boiler. This is done using mills to ensure better combustion
efficiency and higher energy output. The pulverized coal is then mixed with air and blown into the
, boiler for combustion.
Advantages of Pulverization in Thermal Power Stations:
1. Improved Combustion Efficiency
2. Faster and Stable Ignition
3. Higher Thermal Efficiency
4. Reduced Fuel Consumption
1 (e) What are different Types Steam Boilers used In Thermal Power Plants?
Steam boilers in thermal power plants generate steam by heating water using fuels such as coal.
Steam boilers are classified based on various parameters like water circulation, pressure, and design.
Based on Water Flow Configuration:
(a) Fire-Tube Boiler
• Hot gases pass through tubes surrounded by water. This type of boilers are suitable for small
power plants with low pressure and steam demand.
(b) Water-Tube Boiler (Common in Power Plants)
Water flows inside tubes, and hot gases surround them. This type of boilers handles high pressure
and temperature, making it ideal for large power plants.
2 (a) What is a steam power station? Discuss its advantages and disadvantages.
A steam power station, also known as a thermal power station, is a facility that converts heat energy
into electrical energy using steam. In steam power plant, where water is heated in a boiler to
produce steam. This high-pressure steam is then directed onto the blades of a steam turbine, causing
it to spin. The turbine is connected to a generator, which produces electricity.
2 (b) What are the factors considered, while selecting the site for a thermal power station?
Selection of the site for a thermal power station:
,3 Draw and explain the general layout of hydroelectric power plant?
The schematic arrangement of a hydroelectric power plant is shown in figure.
Following are the essential components of the hydro-power plant:
1. Catchment area
2. Reservoir
3. Dam
4. Spillways
5. Penstock
6. Surge tank
7. Prime mover
, 8. Draft tubes
9. Powerhouse and equipment.
Catchment Area
The whole area behind the dam draining into a stream or river across which the dam has been built
at a suitable place is called the catchment area.
Reservoir:
It is the area where the water is stored and utilized for power generation. A reservoir may be natural
or artificial. A natural reservoir is a lake in high mountains. An artificial tank is built by erecting a
dam across the river.
Dam
A dam is a barrier built across the river to store the water for power generation. Dams are built of
concrete or stone masonry, earth, or rockfill. The dam stores the water on one side and on the other
side, it is having a powerhouse to generate the power.
Spill Ways
It is a safety valve for a dam. It is provided to discharge the excess water from the dam to safeguard
the dam against floods.
Penstock
It is a pipe connected between the surge tank and prime mover, usually, these are of steel-reinforced
concrete pipes.
Surge Tank
There is a sudden increase in pressure in the penstock due to the sudden decrease in the rate of water
flow to the turbine when the gates admitting water to the turbines are suddenly closed owing to the
action of the governor. This happens when the load on the generator decreases. This sudden rise of
pressure in the penstock above normal due to reduced load on the generator is known as the “water
hammer”. A surge tank is a small reservoir employed between the dam and the powerhouse nearer
to the powerhouse to reduce the pressure swings in the penstock by allowing the excess water to
enter into the surge tank during low load periods and the stored water can be supplied to the
penstock during high load periods.
Prime Mover
These are the turbines used to convert the kinetic energy of the water into mechanical energy to
produce electric energy.
Draft Tube
It is a diverging discharge passage connected to the tailrace. It supports the runner in utilizing the
