Prayag Khatrani: 2011

Thursday 22 December 2011

HYDRO POWER PLANT

HYDRO POWER PLANT

Worldwide, hydropower plants produce about 24 percent of the world's electricity and supply more than 1 billion people with power. The world's hydropower plants output a combined total of 675,000 megawatts, the energy equivalent of 3.6 billion barrels of oil, according to the National Renewable Energy Laboratory. There are more than 2,000 hydropower plants operating in the United States, making hydropower the country's largest renewable energy source

BLOCK DIAGRAM:

Hydroelectricity is one of the main forms of energy in use today. Its use is being promoted in many countries of the world as a renewable and non-polluting source of energy. The industrialized nations of the world have drawn flak in recent times for releasing high concentrations of green house gases into the atmosphere. The regulations of the Kyoto Protocol are making things tougher. Hence greater interest is being shown in making use of non-polluting energy sources.

EXPLANATION:

FUNCTIONING OF HYDRO POWER PLANT:

Hydroelectricity is produced in a hydroelectric power plant. In this plant, the water is released from a high location. The potential energy present in the water is converted into kinetic energy, which is then used to rotate the blades of a turbine. The turbine is hooked to the generator which produces electricity.

COMPONENTS:

RESERVOIR: The basic requirement of a hydro electric power plant is a good reservoir where large quantity of water is stored during flood season and used during dry season.

DAM: Most hydropower plants rely on a dam that holds back water, creating a large reservoir. Often, this reservoir is used as a recreational lake, such as Lake Roosevelt at the Grand Coulee Dam in Washington State.

PENSTOCK: A pipe between the surge tank and the power house is known as pen stock. A pen stock is a conductor that takes water from the reservoir to the power house. Usually steel, RCC pipes are used. Penstocks are usually equipped with head gates at the inlet which can be closed during the repair of penstocks.

INTAKE: Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads to the turbine. Water builds up pressure as it flows through this pipe.

TURBINE: The water strikes and turns the large blades of a turbine, which is attached to a generator above it by way of a shaft. The most common type of turbine for hydropower plants is the Francis Turbine, which looks like a big disc with curved blades. A turbine can weigh as much as 172 tons and turn at a rate of 90 revolutions per minute (rpm), according to the Foundation for Water & Energy Education (FWEE).

POWER HOUSE: A power house houses the turbine and the generator. The turbine rotates the turbine shaft which in turn rotates the generator shaft, which is coupled to the turbine shaft. Thus the turbine converts hydraulic energy into mechanical energy and the generator converts mechanical energy into electrical energy. The power house is usually at the foot of the dam.

GENERATORS: As the turbine blades turn, so do a series of magnets inside the generator. Giant magnets rotate past copper coils, producing alternating current (AC) by moving electrons.

TRANSFORMER: The transformer inside the powerhouse takes the AC and converts it to higher-voltage current.

POWER LINES: Out of every power plant come four wires: the three phases of power being produced simultaneously plus a neutral or ground common to all three.

OUTFLOW: Used water is carried through pipelines, called tailraces, and re-enters the river downstream.

SURGE TANK: Surge tank is a small additional storage facility near the power house. It is required when there is considerable distance between the power house and the reservoir. When the distance is more non-uniform water intake to the power house results in the bursting of penstocks. In the absence of surge tank, the excess water rushes at the lower end causing the penstock to burst. However in the presence of a surge tank and can be used whenever there is any water shortage. Thus the surge tank acts as a shock absorber or a pressure regulator tank.

TYPES OF HYDRO POWER PLANT:

1. Impoundment: An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level.

2. Diversion: A diversion, sometimes called run-of-river, facility channels a portion of a river through a canal or penstock. It may not require the use of a dam.

3. Pumped Storage: When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity.

Sizes of Hydro power Plants:

Facilities range in size from large power plants that supply many consumers with electricity to small and micro plants that individuals operate for their own energy needs or to sell power to utilities.

1. Large Hydro power plant: Although definitions vary, DOE defines large hydropower as facilities that have a capacity of more than 30 megawatts.

2. Small Hydro power plant: Although definitions vary, DOE defines small hydropower as facilities that have a capacity of 0.1 to 30 megawatts.

3. Micro Hydro power plant: A micro hydropower plant has a capacity of up to 100 kilowatts (0.1 megawatts).

ADVANTAGES:

1. Once a dam is constructed, electricity can be produced at a constant rate.
2. If electricity is not needed, the sluice gates can be shut, stopping electricity generation. The water can be saved for use another time when electricity demand is high.
3. Dams are designed to last many decades and so can contribute to the generation of electricity for many years / decades.
4. The lake that forms behind the dam can be used for water sports and leisure / pleasure activities. Often large dams become tourist attractions in their own right.
5. The lake's water can be used for irrigation purposes.
6. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity.
7. When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere.

DISADVANTAGES:

1. Dams are extremely expensive to build and must be built to a very high standard.
2. The high cost of dam construction means that they must operate for many decades to become profitable.
3. The flooding of large areas of land means that the natural environment is destroyed.
4. People living in villages and towns that are in the valley to be flooded, must move out. This means that they lose their farms and businesses. In some countries, people are forcibly removed so that hydro-power schemes can go ahead.
5. The building of large dams can cause serious geological damage. For example, the building of the Hoover Dam in the USA triggered a number of earth quakes and has depressed the earth’s surface at its location.
6. Although modern planning and design of dams is good, in the past old dams have been known to be breached (the dam gives under the weight of water in the lake). This has led to deaths and flooding.
7. Dams built blocking the progress of a river in one country usually means that the water supply from the same river in the following country is out of their control. This can lead to serious problems between neighbouring countries.

8. Building a large dam alters the natural water table level. For example, the building of the Aswan Dam in Egypt has altered the level of the water table. This is slowly leading to damage of many of its ancient monuments as salts and destructive minerals are deposited in the stone work from ‘rising damp’ caused by the changing water table level.

SITE SELECTION PARAMETERS:

1) Availability of Water

Since the primary requirement for a hydro electric power station, is the availability of huge amount of water such plants should be built at a place (e.g. River, canal) where adequate water is available at a good head.

2) Storage of Water

There are wide variations in water supply from a river or canal during the year. This makes its necessary to store water by constructing a dam in order to ensure the generation of power through out the year. The storage helps in equalizing the flow of water so that any excess quantity of water at a certain period of the year can be made available during times of very low flow in the river. This leads to the conclusion that site selected for hydro electric plant should provide adequate facilities for erecting a dam and storage of water.

3) Cost and Type of Land

The land for the construction of plant should be available at a reasonable price. Further, the bearing capacity of the soil should be adequate to withstand the installation of heavy equipment.

4) Transportation Facilities

The site selected for the hydro-electric plant should be accessible by rail and road so that necessary equipment and machinery could be easily transported.

It is clear from the above mentioned factors that ideal choice of site for such a plant is near a river in hilly areas where dam can be conveniently built and large reservoirs can be obtained.

STATUS OF HYDRO POWER PLANT:

Sr. no.	Power Plant	State	Commissioned Capacity (MW)	year of commission
1	Baira siul	Himachal Pradesh	180	1981
2	Loktak	Manipur	105	1983
3	Salal-I	Jammu & Kashmir	345	1987
4	Tanakpur	Uttarakhand	120	1992
5	Chamera-I	Himachal Pradesh	540	1994
6	Salal-II	Jammu & Kashmir	345	1996
7	Uri-I	Jammu & Kashmir	480	1997
8	Rangit	Sikkim	60	1999
9	Chamera-II	Himachal Pradesh	300	2004
10	Indira Sagar	Madhya Pradesh	1000	2005
11	Dhauliganga-I	Uttarakhand	280	2005
12	Dul Hasti	Jammu & Kashmir	390	2007
13	Omkareshwar	Madhya Pradesh	520	2007
14	Teesta-V	Sikkim	510	2008

CONCLUSION:

After studding hydro power plant we conclude that hydro power plant is easy way to produce electricity. In hydro power plant installation cost is high, but after it constructs its maintenance cost is low. It can easy to start & easy to stop. If water is available for whole year then it is very efficient power plant.

Use below link for more information :

http://en.wikipedia.org/wiki/Hydroelectricity

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Basic Microcontroller Programs

1. 8 bit addition:

clr c

mov a,#10

add a,#09

end

2. 8 bit subtraction:

clr c

mov a,#10

subb a,#09

end

3. 8 bit multiplication:

clr c

mov a,#03h

mov b,#01h

mul ab

mov r1,a

mov r0,b

end

4. 8 bit division:

clr c

mov a,#03h

mov b,#04h

div ab

mov r1,a

mov r0,b

end

5. 16 bit addition:

clr c

mov a,#05h

mov r0,#06h

mov r1,#08h

mov r2,#07h

add a,r1

mov r6,a

mov a,r0

addc a,r2

mov r5,a

end

6. 16 bit subtraction:

clr c

mov a,#05h

mov r0,#06h

mov r1,#08h

mov r2,#07h

subb a,r1

mov r6,a

mov a,r0

subb a,r2

mov r5,a

end

7. 16 bit to 8 bit multiplication:

[ r0b

* a

r6r7 ]

(clr c

mov r0,#43h

mov b,#21h

mov a,#0ah

mul ab

mov r7,a

mov r6,b

mov a,#0ah

mov b,r0

mul ab

add a,r6

jnc next

inc r6

next:mov r6,a

mov r5,b

end)

8. 16 bit to 16 bit multiplication:

[ r0r1

*r2r3

r4r5r6r7 ]

clr c

mov r0,#01fh

mov r1,#02fh

mov r2,#08fh

mov r3,#09fh

mov b,r1

mov a,r3

mul ab

mov r7,a

mov r6,b

mov b,r3

mov a,r0

mul ab

add a,r6

jnc next

inc b

next:mov r6,a

mov r5,b

mov b,r1

mov a,r2

mul ab

add a,r6

jnc next1

inc r5

next1:mov r6,a

mov a,b

add a,r5

jnc next2

inc r4

next2:mov r5,a

mov b,r0

mov a,r2

mul ab

add a,r5

jnc next3

inc r4

next3:mov r5,a

mov a,r4

add a,b

mov r4,a

end

Sunday 4 September 2011

THERMAL POWER PLANT

THERMAL POWER PLANT

Thermal power plants are one of the main sources of electricity in both industrialized and developing countries. These plants have drawn flak on consumption of non-renewable sources of energy at a rapid rate and also since they release huge amounts of greenhouse gases into the atmosphere. The anti-greenhouse gas activists are calling for thermal power to be replaced by other cleaner sources of energy.

EXPLANATION:

Functioning of thermal power plant:

In a thermal power plant, one of coal, oil or natural gas is used to heat the boiler to convert the water into steam. The steam is used to turn a turbine, which is connected to a generator. 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.

Detailed process of power generation in a thermal power plant:

1) Water intake:

Firstly, water is taken into the boiler through a water source. If water is available in a plenty in the region, then the source is an open pond or river. If water is scarce, then it is recycled and the same water is used over and over again.

2) Boiler heating:

The boiler is heated with the help of oil, coal or natural gas. A furnace is used to heat the fuel and supply the heat produced to the boiler. The increase in temperature helps in the transformation of water into steam.

3) Steam Turbine:

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.

4) Generator:

A generator is connected to the steam turbine. When the turbine rotates, the generator produces electricity which is then passed on to the power distribution systems.

5) Special mountings:

There is some other equipment like the economizer and air pre-heater. An economizer uses the heat from the exhaust gases to heat the feed water. An air pre-heater heats the air sent into the combustion chamber to improve the efficiency of the combustion process.

6) Ash collection system:

There is a separate residue and ash collection system in place to collect all the waste materials from the combustion process and to prevent them from escaping into the atmosphere.

Apart from this, there are various other monitoring systems and instruments in place to keep track of the functioning of all the devices. This prevents any hazards from taking place in the plant.

WORKING CYCLE:

Coal & Ash Cycle

Steam& feed water cycle

Air & Flue gases cycle

Cooling water cycle

Electricity generation

Coal and ash cycle:

Coal arrives at storage yard and after necessary handling it passes on to the furnace through fuel feeding system. In case of pulversing system, coal is pulverised and then goes to the fuel burners. Ash resulting from combustion of coal gets collected at the ash pit and is removed to ash storage yard by ash handling equipment.

Air and gas cycle:

Air is taken in from atmosphere through forced draught or induced draught fans and passes to the furnace through air preheater, where it has been heated of the flue gases which pass to chimney via preheater. The hot gases of combustion first flow through boiler tubes, and superheater tubes in furnace then through economiser and then finally through air preheater and then discharges through chimey to the atmosphere.

Feed water and steam cycle:

The condensate leaving the condensor is first heated in a closed water heaters, the bleeded steam from the turbine is used to heat the feed water in the heaters.

In boiler drum and tubes, water circulates due to natural circulation. Wet steam from drum further is heated up in superheater.Steam then expands in turbine and produces power. From there it is exhausted in to condensor. The condensate is collected in hot well. Then it goes to feed water heaters, economiser and to the boiler. Make up water is added in the condensor after purification.

Cooling water cycle:

The condensor requires cooling water to condense the exhaust steam. The water is cooled in cooling tower or in cooling ponds and resued again and again. Some make up cooling water is added in the circuit.

ADVANTAGES:

1. They can be located very conviniently near the load centres.

2. Does not require shielding like required in nuclear power plants.

3.Unlike nuclear power plants whose power production method is difficult, for thermal power plants it is easy if compared.

4. Transmission costs are reduced as they can be set up near the industry.
5. The portion of steam generated can be used as process steam in differentindustries.
6. Steam engines and turbines can work under 25% of overload capacity.
7. Able to respond changing loads without difficulty.

DISADVANTAGES:

1. Large amounts of water are required.
2. Great difficulties experienced in coal handling and disposal of ash.
3. Takes long time to be erected and put into action.
4. Maintenance and operating costs are high.
5. With increase in pressure and temperature, the cost of plant increases.
6. Troubles from smoke and heat from the plant.

SITE SELECTION PARAMETERS:

1) Availability of water

Thermal power plant uses water as working fluid which is repeatedly evaporated and condensed. There is always some water loss and make up water is always required. Water is used in large volumes in a steam power plant for following purposes.

· In boiler to raise the steam

· For cooling purposes such as in condensers

· As a carrying medium such as in disposal of ash

· For drinking purpose.

Thus for a 250MW power station, cooling water required may be 62X106 litres per hour and make up water required may be something 1 million litre per hour. So while selecting a site for the thermal power plant, water is the most important factor.

2) Land:

Considerable area is required for a power station. For a 2000MW plant, the land requirement may be of order of 250 to 300 acres.The cost of land should be reasonable. Staff colony, coal storage, ash disposal requires appropriate amount of land. If the site is far away from a big city then entirely new facilities such as marketing, dairies, etc will have to be provided for the staff.
The distribution of land can be
Building=10%
Coal storage= 33%
Cooling towers= 27%
Switch yard=7%
Other areas= 23%
Hence land is also an important factor for site selection of thermal power station.

3) Availability of raw material:

Modern steam power stations using coal and oil as fuel require large quantity of it per annum. A plant consumes a large quantity of coal so it should be located as near as possible to the coal fields to save the transportation charges. Besides transportation charges a plant located away from the coal fields may face some problems like, there may be failure of transportation system, strike at the mines, etc.

STATUS OF THERMAL POWER PLANT:

for status of international status use below link :
http://en.wikipedia.org/wiki/List_of_coal_power_stations
FOR INDIA:

STATE NAME OF POWER STATION CAPACITY (MW)

1. ANDHRA PRADESH Kothagndam 240

2 ASSAM Gauhati 40

3 BIHAR Barauni 150

Bokaro 225

Patratu 400

4 DELHI Rajghat 200

Indraprashstha 350

Badarpur 300

5 GUJARAT Dhuvaran 530

Ukai 240

6 HARAYANA Faridabad 200

Panipat 220

7 MADHYA PRADESH Kobra 420

Satpura 300

8 MAHARASHRTRA Nagpur (koradi) 480

Nashik 280

Paras 90

9 ORISSA Talcher 254

10 TAMILNADU Neyvelli 600

Eunose 450

11 UTTARPRADESH Harduaganj 540

Obra 550

12 WEST BENGAL Samtaldih 480

Chandrapur 420

CONCLUSION:

After studying thermal power plant we conclude that thermal power plant is easy way to produce electricity. Row material of the Thermal power plant is COAL & it is easily available. But Thermal power plant is more dangerous for environment.

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