Various Components Of Thermal Power Plant - Basics
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Various Components Of Thermal Power Plant - Basics as PDF for free.
More details
- Words: 1,802
- Pages: 17
UNIVERSITY OF PETROLEUM & ENERGY STUDIES
VARIOUS COMPONENTS OF POWER PLANT
| Mohammed Kabiruddin
Various Components of Power Plant
Contents Boiler Turbine Deaerator Heat Exchangers Super Heater Economizers Condenser Feed water heater Electrical generator Bibliography
Page 2
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Thermal Power Station
1.
Boiler
A boiler is an enclosed vessel that provides a means for combustion heat to be transferred into water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. Water is a useful and cheap medium for transferring heat to a process. When water is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be extremely dangerous equipment that must be treated with utmost care. The process of heating a liquid until it reaches its gaseous state is called evaporation. Heat is transferred from one body to another by means of
Page 3
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
(1) Radiation, which is the transfer of heat from a hot body to a cold body without a conveying medium, (2) Convection, the transfer of heat by a conveying medium, such as air or water and (3) Conduction, transfer of heat by actual physical contact, molecule to molecule. A. Boiler Systems
The boiler system comprises of: feed water system, steam system and fuel system. The feed water system provides water to the boiler and regulates it automatically to meet the steam demand. Various valves provide access for maintenance and repair. The steam system collects and controls the steam produced in the boiler. Steam is directed through a piping system to the point of use.
Page 4
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment required in the fuel system depends on the type of fuel used in the system. A typical boiler room schematic is shown in Figure. The water supplied to the boiler that is converted into steam is called feed water. The two sources of feed water are: (1) Condensate or condensed steam returned from the processes and (2) Makeup water (treated raw water) which must come from outside the boiler room and plant processes. For higher boiler efficiencies, the feed water is preheated by economizer, using the waste heat in the flue gas. There are virtually infinite numbers of boiler designs but generally they fit into one of two categories:
1. Fire tube or "fire in tube" boilers; contain long steel tubes through which the hot gasses from a furnace pass and around which the water to be converted to steam circulates. Fire tube boilers, typically have a lower initial cost, are more fuel efficient and easier to operate, but they are limited generally to capacities of 25 tons/hr and pressures of 17.5 2
kg/cm .
Page 5
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
2. Water tube or "water in tube" boilers in which the conditions are reversed with the water passing through the tubes and the hot gasses passing outside the tubes. These boilers can be of single- or multipledrum type. These boilers can be built to any steam capacities and pressures, and have higher efficiencies than fire tube boilers.
Page 6
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
2.
Turbine
Turbine, rotary engine that converts the energy of a moving stream of water, steam, or gas into mechanical energy. The basic element in a turbine is a wheel or rotor with paddles, propellers, blades, or buckets arranged on its circumference in such a fashion that the moving fluid exerts a tangential force that turns the wheel and imparts energy to it. This mechanical energy is then transferred through a drive shaft to operate a machine, compressor, electric generator, or propeller. Turbines are classified as hydraulic, or water, turbines, steam turbines, or gas turbines. Today turbine-powered generators produce most of the world's electrical energy. Windmills that generate electricity are known as wind turbines.
Page 7
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
3.
Deaerator
A deaerator is a device that is widely used for the removal of air and other dissolved gases from the feed water to steam generating boilers. In particular, dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). It also combines with any dissolved carbon dioxide to form carbonic acid that causes further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.0005 cm³/L) or less.
Page 8
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
4.
Heat Exchangers
Heat exchangers are equipment that transfers heat from one medium to another. The proper design, operation and maintenance of heat exchangers will make the process energy efficient and minimize energy losses. Heat exchanger performance can deteriorate with time, off design operations and other interferences such as fouling, scaling etc. It is necessary to assess periodically the heat exchanger performance in order to maintain them at a high efficiency level.
Heat exchangers may be classified according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counterflow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is most efficient, in that it can transfer the most heat. See countercurrent exchange. In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger.
Page 9
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
For efficiency, heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchanger's performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence. The driving temperature across the heat transfer surface varies with position, but an appropriate mean temperature can be defined. In most simple systems this is the log mean temperature difference (LMTD). Sometimes direct knowledge of the LMTD is not available and the NTU method is used.
Page 10
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
5.
Super Heater
A super heater is a device in a steam engine that heats the steam generated by the boiler again, increasing its thermal energy and decreasing the likelihood that it will condense inside the engine. Super heaters increase the efficiency of the steam engine, and were widely adopted. Steam which has been superheated is logically known as superheated steam; non-superheated steam is called saturated steam or wet steam.
Super heaters were applied to steam locomotives in quantity from the early 20th century, to most steam vehicles, and to stationary steam engines including power stations.
Page 11
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
6.
Condenser
The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausters for continuous removal of air and gases from the steam side to maintain vacuum. For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 oC where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum.
Page 12
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Thus leaks of non-condensable air into the closed loop must be prevented. Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning. The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once-through water from a river, lake or ocean.
Page 13
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
7.
Economizers
Economizers, or in British English economisers, are mechanical devices intended to reduce energy consumption, or to perform another useful function like preheating a fluid. The term economizer is used for other purposes as well. In simple terms, an economizer is a heat exchanger.
Page 14
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
8.
Feed water heater
In the case of a conventional steam-electric power plant utilizing a drum boiler, the surface condenser removes the latent heat of vaporization from the steam as it changes states from vapour to liquid. The heat content (btu) in the steam is referred to as Enthalpy. The condensate pump then pumps the condensate water through a feed water heater. The feed water heating equipment then raises the temperature of the water by utilizing extraction steam from various stages of the turbine. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle.
Page 15
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
9.
Electrical generator:-
In electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction. The reverse conversion of electrical energy into mechanical energy is done by a motor, and motors and generators have many similarities. A generator forces electric charges to move through an external electrical circuit, but it does not create electricity or charge, which is already present in the wire of its windings. It is somewhat analogous to a water pump, which creates a flow of water but does not create the water inside. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, the sun or solar energy, compressed air or any other source of mechanical energy.
Page 16
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
10. Bibliography 1. http://en.wikipedia.org/wiki/Thermal_power_station 2. http://en.wikipedia.org/wiki/Deaerator 3. http://en.wikipedia.org/wiki/Economiser 4. http://en.wikipedia.org/wiki/Regenerative_heat_exchanger 5. http://www.tva.gov/power/coalart.htm 6. http://images.google.co.in/images?um=1&hl=en&q=feed+water+heater &start=18&sa=N&ndsp=18
Page 17
Mohammed Kabiruddin, MS-ES, UPES
VARIOUS COMPONENTS OF POWER PLANT
| Mohammed Kabiruddin
Various Components of Power Plant
Contents Boiler Turbine Deaerator Heat Exchangers Super Heater Economizers Condenser Feed water heater Electrical generator Bibliography
Page 2
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Thermal Power Station
1.
Boiler
A boiler is an enclosed vessel that provides a means for combustion heat to be transferred into water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. Water is a useful and cheap medium for transferring heat to a process. When water is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be extremely dangerous equipment that must be treated with utmost care. The process of heating a liquid until it reaches its gaseous state is called evaporation. Heat is transferred from one body to another by means of
Page 3
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
(1) Radiation, which is the transfer of heat from a hot body to a cold body without a conveying medium, (2) Convection, the transfer of heat by a conveying medium, such as air or water and (3) Conduction, transfer of heat by actual physical contact, molecule to molecule. A. Boiler Systems
The boiler system comprises of: feed water system, steam system and fuel system. The feed water system provides water to the boiler and regulates it automatically to meet the steam demand. Various valves provide access for maintenance and repair. The steam system collects and controls the steam produced in the boiler. Steam is directed through a piping system to the point of use.
Page 4
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipment required in the fuel system depends on the type of fuel used in the system. A typical boiler room schematic is shown in Figure. The water supplied to the boiler that is converted into steam is called feed water. The two sources of feed water are: (1) Condensate or condensed steam returned from the processes and (2) Makeup water (treated raw water) which must come from outside the boiler room and plant processes. For higher boiler efficiencies, the feed water is preheated by economizer, using the waste heat in the flue gas. There are virtually infinite numbers of boiler designs but generally they fit into one of two categories:
1. Fire tube or "fire in tube" boilers; contain long steel tubes through which the hot gasses from a furnace pass and around which the water to be converted to steam circulates. Fire tube boilers, typically have a lower initial cost, are more fuel efficient and easier to operate, but they are limited generally to capacities of 25 tons/hr and pressures of 17.5 2
kg/cm .
Page 5
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
2. Water tube or "water in tube" boilers in which the conditions are reversed with the water passing through the tubes and the hot gasses passing outside the tubes. These boilers can be of single- or multipledrum type. These boilers can be built to any steam capacities and pressures, and have higher efficiencies than fire tube boilers.
Page 6
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
2.
Turbine
Turbine, rotary engine that converts the energy of a moving stream of water, steam, or gas into mechanical energy. The basic element in a turbine is a wheel or rotor with paddles, propellers, blades, or buckets arranged on its circumference in such a fashion that the moving fluid exerts a tangential force that turns the wheel and imparts energy to it. This mechanical energy is then transferred through a drive shaft to operate a machine, compressor, electric generator, or propeller. Turbines are classified as hydraulic, or water, turbines, steam turbines, or gas turbines. Today turbine-powered generators produce most of the world's electrical energy. Windmills that generate electricity are known as wind turbines.
Page 7
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
3.
Deaerator
A deaerator is a device that is widely used for the removal of air and other dissolved gases from the feed water to steam generating boilers. In particular, dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). It also combines with any dissolved carbon dioxide to form carbonic acid that causes further corrosion. Most deaerators are designed to remove oxygen down to levels of 7 ppb by weight (0.0005 cm³/L) or less.
Page 8
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
4.
Heat Exchangers
Heat exchangers are equipment that transfers heat from one medium to another. The proper design, operation and maintenance of heat exchangers will make the process energy efficient and minimize energy losses. Heat exchanger performance can deteriorate with time, off design operations and other interferences such as fouling, scaling etc. It is necessary to assess periodically the heat exchanger performance in order to maintain them at a high efficiency level.
Heat exchangers may be classified according to their flow arrangement. In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counterflow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is most efficient, in that it can transfer the most heat. See countercurrent exchange. In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger.
Page 9
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
For efficiency, heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing resistance to fluid flow through the exchanger. The exchanger's performance can also be affected by the addition of fins or corrugations in one or both directions, which increase surface area and may channel fluid flow or induce turbulence. The driving temperature across the heat transfer surface varies with position, but an appropriate mean temperature can be defined. In most simple systems this is the log mean temperature difference (LMTD). Sometimes direct knowledge of the LMTD is not available and the NTU method is used.
Page 10
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
5.
Super Heater
A super heater is a device in a steam engine that heats the steam generated by the boiler again, increasing its thermal energy and decreasing the likelihood that it will condense inside the engine. Super heaters increase the efficiency of the steam engine, and were widely adopted. Steam which has been superheated is logically known as superheated steam; non-superheated steam is called saturated steam or wet steam.
Super heaters were applied to steam locomotives in quantity from the early 20th century, to most steam vehicles, and to stationary steam engines including power stations.
Page 11
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
6.
Condenser
The surface condenser is a shell and tube heat exchanger in which cooling water is circulated through the tubes. The exhaust steam from the low pressure turbine enters the shell where it is cooled and converted to condensate (water) by flowing over the tubes as shown in the adjacent diagram. Such condensers use steam ejectors or rotary motor-driven exhausters for continuous removal of air and gases from the steam side to maintain vacuum. For best efficiency, the temperature in the condenser must be kept as low as practical in order to achieve the lowest possible pressure in the condensing steam. Since the condenser temperature can almost always be kept significantly below 100 oC where the vapor pressure of water is much less than atmospheric pressure, the condenser generally works under vacuum.
Page 12
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
Thus leaks of non-condensable air into the closed loop must be prevented. Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning. The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once-through water from a river, lake or ocean.
Page 13
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
7.
Economizers
Economizers, or in British English economisers, are mechanical devices intended to reduce energy consumption, or to perform another useful function like preheating a fluid. The term economizer is used for other purposes as well. In simple terms, an economizer is a heat exchanger.
Page 14
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
8.
Feed water heater
In the case of a conventional steam-electric power plant utilizing a drum boiler, the surface condenser removes the latent heat of vaporization from the steam as it changes states from vapour to liquid. The heat content (btu) in the steam is referred to as Enthalpy. The condensate pump then pumps the condensate water through a feed water heater. The feed water heating equipment then raises the temperature of the water by utilizing extraction steam from various stages of the turbine. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle.
Page 15
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
9.
Electrical generator:-
In electricity generation, an electrical generator is a device that converts mechanical energy to electrical energy, generally using electromagnetic induction. The reverse conversion of electrical energy into mechanical energy is done by a motor, and motors and generators have many similarities. A generator forces electric charges to move through an external electrical circuit, but it does not create electricity or charge, which is already present in the wire of its windings. It is somewhat analogous to a water pump, which creates a flow of water but does not create the water inside. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, the sun or solar energy, compressed air or any other source of mechanical energy.
Page 16
Mohammed Kabiruddin, MS-ES, UPES
Various Components of Power Plant
10. Bibliography 1. http://en.wikipedia.org/wiki/Thermal_power_station 2. http://en.wikipedia.org/wiki/Deaerator 3. http://en.wikipedia.org/wiki/Economiser 4. http://en.wikipedia.org/wiki/Regenerative_heat_exchanger 5. http://www.tva.gov/power/coalart.htm 6. http://images.google.co.in/images?um=1&hl=en&q=feed+water+heater &start=18&sa=N&ndsp=18
Page 17
Mohammed Kabiruddin, MS-ES, UPES
Related Documents
Thermal Power Plant
June 2020 22
Presentation Of Thermal Power Plant
May 2020 10
Thermal Power Plant
June 2020 15
Thermal Power Plant Auditing
June 2020 13
Nuclear Power Plant Components
May 2020 19More Documents from "Er. Amar Kumar"
Economies Related To Wind & Solar Energy
May 2020 13
Heat Exchangers
May 2020 9
Coal Liquefaction
May 2020 18
Coal Bed Methane
May 2020 13
