Basics Of Hydro Power Plant
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hydro-electric power plant
It plays very important role in the development of country. It provides power at cheapest rate. About 20% of the total world power is generated using hydro power plants.
1.
Fuels.
2.
Energy storage of water.
3.
Nuclear energy.
4.
Wind energy.
5.
Tidal energy.
6.
Solar energy.
7.
Geothermal energy.
8.
Thermo electric power
Thermal Power Generation system.
Hydro electric Power Generation system.
Nuclear Power Generation system.
Diesel Power Generation system.
Non conventional energy power Generation system.
TYPES OF HYDRO ELECTRIC POWER STATION.
ADVANTAGES.
DISADVANTAGES.
PARTS OF HYDRO ELECTRIC POWER STATION.
LAW HEAD SCHEME.
SITE SILECTION OF HYDRO POWER STATION.
HIGH HEAD SCHEME.
MEDIUM HEAD SCHEME.
http://www1.eere.energy.gov/windandhydro/hydro_how.html
8
Meteorology
◦ Study of the atmosphere including weather and climate.
Surface water hydrology ◦ Flow and occurrence of water on the surface of the earth.
Hydrogeology
◦ Flow and occurrence of ground water.
Watersheds
Hydrology may be defined as the science which deals with the depletion and replenishment of water resources. It deals with surface water as well as ground water. It is also concerned with transportation of water from one place to another. MASS CURVE Mass curve is the graph of cumulative values of water quantity against time.
◦ There are many types of hydrographs. Hydrograph is defined as a graph showing discharge of flowing water with respect to time for a specified time.
Graph of stream flow vs. time Obtained by means of a continuous recorder which indicates stage vs. time (stage hydrograph) Transformed to a discharge hydrograph by application of a rating curve. Typically are complex multiple peak curves Available on the web.
storm of Duration D Precipitation
P
tl tp
peak flow
Discharge Q
baseflow new baseflow
w/o rainfall Time
If we measure the rainfall and put it on a time graph and link that to the amount of water in the river, we have some really useful information! This graph is hydrograph. It plots rainfall against discharge (that is the amount of water in the river as it passes a particular point measured in cubic metres per seconds or cumecs). Changes measured over time is river regime - eg. in winter there is more rain, less evaporation, less vegetation to absorb it.
Rate of flow at any instant during the duration period. Total volume of flow upto that instant as the area under hydrograph denotes the volume of water in that duration. The mean annual run-off. The minimum and maximum run-off for the year.
Flow duration curve is a useful form to represent the run-off data for the given time. This curve is plotted between flow available during a period versus the fraction of time.
The flow duration curve is drawn with the help of hydrograph from the available run-off data and is necessary to find out the time duration for which flows available .
The potential is about 84000 MW at 60% load factor spread across six major basins in the country. Pumped storage sites have been found recently which leads to a further addition of a maximum of 94000 MW. Annual yield is assessed to be about 420 billion units per year though with seasonal energy the value crosses600 billion mark. The possible installed capacity is around 150000 MW (Based on the report submitted by CEA to the Ministry of Power)
The proportion of hydro power increased from 35% from the first five year plan to 46% in the third five year plan but has since then decreased continuously to 25% in 2001. The theoretical potential of small hydro power is 10071 MW. Currently about 17% of the potential is being harnessed.
About 6.3% is still under construction.
NAME
STATA
CAPACITY (MW)
BHAKRA
PUNJAB
1100
NAGARJUNA
ANDHRA PRADESH
960
KOYNA
MAHARASHTRA
920
DEHAR
HIMACHAL PRADESH
990
SHARAVATHY
KARNATAKA
891
KALINADI
KARNATAKA
810
SRISAILAM
ANDHRA PRADESH
770
POWER HOUSE
RESEVOIR
PENSTOCK
DAM
TURBINE INTAKE
TRANSFORMER
GENERATOR
POWER LINE
Water from the reservoir flows due to gravity to drive the turbine. Turbine is connected to a generator. Power generated is transmitted over power lines.
A water turbine that convert the energy of flowing or falling water into mechanical energy that drives a generator, which generates electrical power. This is a heart of hydropower power plant. A control mechanism to provide stable electrical power. It is called governor. Electrical transmission line to deliver the power to its destination.
Large plants : capacity >30 MW Small Plants : capacity b/w 100 kW to 30 MW Micro Plants : capacity up to 100 kW
Pico hydroelectric plant. ◦ Up to 10kW, remote areas, away from the grid. Micro hydroelectric plant ◦ Capacity 10kW to 300kW, usually provided power for small community or rural industry in remote areas away from the grid. Small hydroelectric plant. ◦ Capacity 300kW to 1MW Mini hydroelectric plant. ◦ Capacity above 1MW Medium hydroelectric plant. ◦ 15 - 100 MW usually feeding a grid. Large hydroelectric plant. ◦ More than 100 MW feeding into a large electricity grid.
•
CLASSIFICATION BASED ON HEAD.
A.
High head plant
B.
Medium head plant. (60m to 300 m.)
C.
Low head plant. ( > 60m.)
•
( < 300 m.)
CLASSIFICATION BASED ON WATER CONDITION.
A.
Flow of water plant.
B.
Storage of water plant.
C.
Pump storage water plant.
Many creeks and rivers are permanent, they never dry up, and these are the most suitable for micro-hydro power production. Micro hydro turbine could be a water-wheel turbine, Pelton wheel. (most common turbine). Others : Turgo, Cross-flow and various axial flow turbines.
Head ◦ Water must fall from a higher elevation to a lower one to release its stored energy. ◦ The difference between these elevations (the water levels in the forebay and the tailbay) is called head.
Dams: Are of three categories. ◦ high-head (800 or more feet) ◦ medium-head (100 to 800 feet) ◦ low-head (less than 100 feet)
Power
is
proportional
to
the
product
of
head x flow http://www.wapa.gov/crsp/info/harhydro.htm
27
Large-hydro ◦ More than 100 MW feeding into a large electricity grid.
Medium-hydro ◦ 15 - 100 MW usually feeding a grid.
Small-hydro ◦ 1 - 15 MW - usually feeding into a grid.
Mini-hydro ◦ Above 100 kW, but below 1 MW.
Micro-hydro ◦ From 5kW up to 100 kW ◦ Usually provided power for a small community or rural industry in remote areas away from the grid.
Pico-hydro ◦ From a few hundred watts up to 5kW. ◦ Remote areas away from the grid.
•
Classification based on operation.
A.
Manual plant.
B.
Automatic plant.
•
Classification based on type of load.
A.
B.
Base load plant.
Peak load plant.
1.
Reservoir.
2.
Catchments area.
3.
Dam.
(a) Earthen dam.
(b) Masonry dam.
(c) Concrete dam.
4. Spill ways.
5. Screen.
6. Fore bay or Intake.
7. Tunnel.
8. Penstock or pipe line.
9. Surge tank.
10. Draft tube.
11. Tail race.
12. Fish passes.
13. Turbine.
1.High head schemes.
2.Medium head schemes.
3.Low head schemes.
1.High head schemes. (Impulse turbine, pelton wheel)
2.Medium head schemes. (reaction turbine )
3.Low head schemes. (propeller turbine )
Used in remote locations in northern Canada
base load capacity
◦ Water flows downhill during day/peak periods
Typical efficiency of 70 – 85%Completed 1967 Capacity – 324 MW ◦ Two 162 MW units.
Purpose – energy storage
◦ Water pumped uphill at night Low usage – excess
36
There is substantial increase in peak load capacity of plant at comparatively low capital cost. There is an improvement in the load factor of plant. Load on hydro-electrical plant remains uniform.
Name
Country
Year
Max Generation
Annual Production
Three Gorges
China
2009
18,200 MW
Itaipú
Brazil/Paraguay
1983
12,600 MW
93.4 TW-hrs
Guri
Venezuela
1986
10,200 MW
46 TW-hrs
Grand Coulee
United States
1942/80
6,809 MW
22.6 TW-hrs
Sayano Shushenskaya
Russia
1983
6,400 MW
Robert-Bourassa
Canada
1981
5,616 MW
Churchill Falls
Canada
1971
5,429 MW
35 TW-hrs
Iron Gates
Romania/Serbia
1970
2,280 MW
11.3 TW-hrs
Ranked by maximum power.
“Hydroelectricity,” Wikipedia.org
38
Arch Gravity Buttress Embankment or Earth
FIRST ELEMENT :-
DAMS
Arch shape gives strength Less material (cheaper) Narrow sites Need strong abutments
Weight holds dam in place. Lots of concrete. (expensive)
Face is held up by a series of supports. Flat or curved face.
Boyle, Renewable Energy, 2nd edition, Oxford University Press, 2003
44
Head Pressure
Impulse
High
Medium
Low
Pelton Turgo Multi-jet Pelton
Crossflow Turgo Multi-jet Pelton
Crossflow
Francis Pump-as-Turbine
Propeller Kaplan
Reaction
Boyle, Renewable Energy, 2nd edition, Oxford University Press, 2003
Francis Turbine Kaplan Turbine Pelton Turbine Turgo Turbine New Designs
Specific speed; high specific speed is essential where head is low. Rotational speed; Efficiency; Part of load operation; Cavitations; Disposition of turbine shaft; Head;
Reaction Turbines ◦ ◦ ◦ ◦
Derive power from pressure drop across turbine. Totally immersed in water. Angular & linear motion converted to shaft power. Propeller, Francis, and Kaplan turbines
Impulse Turbines ◦ Convert kinetic energy of water jet hitting buckets. ◦ No pressure drop across turbines. ◦ Pelton, Turgo, and crossflow turbines
Uses the velocity of the water to move the runner and discharges to atmospheric pressure. The water stream hits each bucket on the runner. High head, low flow applications. Types : Pelton turbine, Turgo turbine
Uses the velocity of the water to move the runner and discharges to atmospheric pressure.
The water stream hits each bucket on the runner.
No suction downside, water flows out through turbine housing after hitting. High head, low flow applications. Types : Pelton wheel, Cross Flow
Combined action of pressure and moving water. Runner placed directly in the water stream flowing over the blades rather than striking each individually. Lower head and higher flows than compared with the impulse turbines.
It is run-of-river power plant. Do not worry about the turbidity of water. There is no danger of cavitations. It is simple to construct, repaired and maintenance.
The slow rotation of chain turbine leads to high speed ratios when connect to generator at 600 rpm – 1500 rpm. This chain turbine operation is very noisy. Structure of turbine is very big.
Nozzles direct forceful streams of water against a series of spoon-shaped buckets mounted around the edge of a wheel. Each bucket reverses the flow of water and this impulse spins the turbine.
Suited for high head, low flow sites. The largest units can be up to 200 MW. Can operate with heads as small as 15 meters and as high as 1,800 meters.
Kaplan Francis Pelton Turgo
2 10 50 50
< < < <
H < 40 H < 350 H < 1300 H < 250
(where H = head in meters)
Constr uction of Turbine.
Inlet Outlet Impulse turbine for High head plant.
Medium head plant
Medium head plant
Propeller turbine for low head plant.
Its function is to prevent sudden increase of pressure in the supply line or in the penstock. It is placed as near as possible to the turbine. Water hammer Due to the variation in the demand of water supply according to load, the turbine gates get closed suddenly which cause increase in pressure. This is known as water hammer.
Tailraces:-
What is the function of Spill ways?
1.
The plant is simple in construction ,robust and required low maintenance.
2.
It can be put in the service instantly.
3.
It can respond to changing loads without any difficulty.
4.
There are no stand by losses.
5.
The running charges are very small.
6.
No fuels is burnt.
7.
The plant is quite neat and clean.
8.
The water after running the turbine can be used for irrigation and other purpose.
1.
The capital cost of generators, civil engineering work etc is high.
2.
High cost of transmission lines.
3.
Long dry seasons may effect the delivery of power.
1.
sufficient quantity of water at a reasonable head should be available.
2.
The site should allow for strong foundations with minimum cost.
3.
There should be no possibility of future source of leakage of water.
4.
The selected site should be accessible easily.
5.
There should be possibility of stream diversion during construction period.
6.
The reservoir to be constructed should have large catchments area, so that the water in it should never fall below the minimum level.
Environmental Benefits of Hydro power plant. • No operational greenhouse gas emissions. Non-environmental benefits – flood control, irrigation, transportation, fisheries and tourism.
The loss of land under the reservoir. Interference with the transport of sediment by the dam. Problems associated with the reservoir.
◦ Climatic and seismic effects. ◦ Impact on aquatic ecosystems, flora and fauna.
A large area is taken up in the form of a reservoir in case of large dams.
This leads to inundation of fertile alluvial rich soil in the flood plains, forests and even mineral deposits and the potential drowning of archeological sites.
Power per area ratio is evaluated to quantify this impact. Usually ratios lesser than 5 KW per hectare implies that the plant needs more land area than competing renewable resources. However this is only an empirical relation.
Capture of sediment decreases the fertility downstream as a long term effect. It also leads to deprivation of sand to beaches in coastal areas. If the water is diverted out of the basin, there might be salt water intrusion into the inland from the ocean, as the previous balance between this salt water and upstream fresh water in altered. It may lead to changes in the ecology of the estuary area and lead to decrease in agricultural productivity.
It is believed that large reservoirs induce have the potential to induce earthquakes.
In tropics, existence of man-made lakes decreases the convective activity and reduces cloud cover. In temperate regions, fog forms over the lake and along the shores when the temperature falls to zero and thus increases humidity in the nearby area.
P g Q H P 10 Q H
P = power in kilowatts (kW) g = gravitational acceleration (9.81 m/s2) = turbo-generator efficiency (0
Non –toxic dust Sulphurous anhydride Carbon monoxide Nitrogen dioxide Soot (fly ash) Hydrogen sulphide Pollution can be define as the contamination of soil, air and water with undesirable amount of material and heat.
Acid rain; the rain which contain acid as its constituents, brings all the acid down from high above the environment.
Contaminant; it is the another name of pollution. It is undesirable substances which may be physical, chemical or biological.
Pollutant; these are undesirable substances
present in the environment these can be NO2, SO2, CO2,smoke,salt, bacteria.
Greater reliability of supply to the consumers. Avoid complete shut down. The overall cost of energy per unit of an interconnected system is less. There is a more effective use of transmission line facilities. Less capital investment required. Less expenses on supervision, operation and maintenance.
Due to limited generating capacity diesel power stations is not suitable for base load plants. Nuclear power stations is not suitable for peak load plants.
Incremental rate curve shows that as output power increases, cost of plant also increases.
Flat rate tariff; by estimating load factor and diversity factor for various uses of electricity, we may merge the equitable contributation to the fixed charge of a particular class of consumers with each KWH consumption, the resultant tariff is a Flat rate tariff .
Two part tariff; total charge is split into two components i.e. a fixed charge depend upon the maximum demand and a variable charge based upon the energy consumption.
Block rate tariff; using this tariff, the fixed charge is merged into the unit charge for one or two blocks of consumption, all units in excess being charged at low unit rate. Maximum demand tariff; these tariff differ from two part tariff only in the sense that maximum demand is actually measured by a demand indicator instead of assessing it merely on the bases of ratable value. Power factor tariff; power factor tariffs are devised to make a distinction between overall charge per unit to be recovered from two types of consumers, one having a good power factor and the other having a poor power factor.
Wind power plants is least reliable, and hydro power plants are most reliable. The power output from hydro power plant depends on discharge, head and system efficiency. The power output from hydro power plant in KW is given by 0.736Qwhή/75 In hydro power plant the operating cost is low but the initial cost is high. Gross head of an hydro power station is the difference of water level between in the storage and tail race.
The flow duration curve at a given head of hydro power plant is used to determine total power available at the site. The draft tube is provided to increase the acting head on the water wheel. For low head power plants kaplan turbines are used. For high head and low discharge power plants pelton wheel turbines are used. 1.25 The specific speed (Ns) of a turbine is given by Ns=N√P/H The specific speed (Ns) of a turbine is the speed at which the turbine develops unit horse power at unit head.
It plays very important role in the development of country. It provides power at cheapest rate. About 20% of the total world power is generated using hydro power plants.
1.
Fuels.
2.
Energy storage of water.
3.
Nuclear energy.
4.
Wind energy.
5.
Tidal energy.
6.
Solar energy.
7.
Geothermal energy.
8.
Thermo electric power
Thermal Power Generation system.
Hydro electric Power Generation system.
Nuclear Power Generation system.
Diesel Power Generation system.
Non conventional energy power Generation system.
TYPES OF HYDRO ELECTRIC POWER STATION.
ADVANTAGES.
DISADVANTAGES.
PARTS OF HYDRO ELECTRIC POWER STATION.
LAW HEAD SCHEME.
SITE SILECTION OF HYDRO POWER STATION.
HIGH HEAD SCHEME.
MEDIUM HEAD SCHEME.
http://www1.eere.energy.gov/windandhydro/hydro_how.html
8
Meteorology
◦ Study of the atmosphere including weather and climate.
Surface water hydrology ◦ Flow and occurrence of water on the surface of the earth.
Hydrogeology
◦ Flow and occurrence of ground water.
Watersheds
Hydrology may be defined as the science which deals with the depletion and replenishment of water resources. It deals with surface water as well as ground water. It is also concerned with transportation of water from one place to another. MASS CURVE Mass curve is the graph of cumulative values of water quantity against time.
◦ There are many types of hydrographs. Hydrograph is defined as a graph showing discharge of flowing water with respect to time for a specified time.
Graph of stream flow vs. time Obtained by means of a continuous recorder which indicates stage vs. time (stage hydrograph) Transformed to a discharge hydrograph by application of a rating curve. Typically are complex multiple peak curves Available on the web.
storm of Duration D Precipitation
P
tl tp
peak flow
Discharge Q
baseflow new baseflow
w/o rainfall Time
If we measure the rainfall and put it on a time graph and link that to the amount of water in the river, we have some really useful information! This graph is hydrograph. It plots rainfall against discharge (that is the amount of water in the river as it passes a particular point measured in cubic metres per seconds or cumecs). Changes measured over time is river regime - eg. in winter there is more rain, less evaporation, less vegetation to absorb it.
Rate of flow at any instant during the duration period. Total volume of flow upto that instant as the area under hydrograph denotes the volume of water in that duration. The mean annual run-off. The minimum and maximum run-off for the year.
Flow duration curve is a useful form to represent the run-off data for the given time. This curve is plotted between flow available during a period versus the fraction of time.
The flow duration curve is drawn with the help of hydrograph from the available run-off data and is necessary to find out the time duration for which flows available .
The potential is about 84000 MW at 60% load factor spread across six major basins in the country. Pumped storage sites have been found recently which leads to a further addition of a maximum of 94000 MW. Annual yield is assessed to be about 420 billion units per year though with seasonal energy the value crosses600 billion mark. The possible installed capacity is around 150000 MW (Based on the report submitted by CEA to the Ministry of Power)
The proportion of hydro power increased from 35% from the first five year plan to 46% in the third five year plan but has since then decreased continuously to 25% in 2001. The theoretical potential of small hydro power is 10071 MW. Currently about 17% of the potential is being harnessed.
About 6.3% is still under construction.
NAME
STATA
CAPACITY (MW)
BHAKRA
PUNJAB
1100
NAGARJUNA
ANDHRA PRADESH
960
KOYNA
MAHARASHTRA
920
DEHAR
HIMACHAL PRADESH
990
SHARAVATHY
KARNATAKA
891
KALINADI
KARNATAKA
810
SRISAILAM
ANDHRA PRADESH
770
POWER HOUSE
RESEVOIR
PENSTOCK
DAM
TURBINE INTAKE
TRANSFORMER
GENERATOR
POWER LINE
Water from the reservoir flows due to gravity to drive the turbine. Turbine is connected to a generator. Power generated is transmitted over power lines.
A water turbine that convert the energy of flowing or falling water into mechanical energy that drives a generator, which generates electrical power. This is a heart of hydropower power plant. A control mechanism to provide stable electrical power. It is called governor. Electrical transmission line to deliver the power to its destination.
Large plants : capacity >30 MW Small Plants : capacity b/w 100 kW to 30 MW Micro Plants : capacity up to 100 kW
Pico hydroelectric plant. ◦ Up to 10kW, remote areas, away from the grid. Micro hydroelectric plant ◦ Capacity 10kW to 300kW, usually provided power for small community or rural industry in remote areas away from the grid. Small hydroelectric plant. ◦ Capacity 300kW to 1MW Mini hydroelectric plant. ◦ Capacity above 1MW Medium hydroelectric plant. ◦ 15 - 100 MW usually feeding a grid. Large hydroelectric plant. ◦ More than 100 MW feeding into a large electricity grid.
•
CLASSIFICATION BASED ON HEAD.
A.
High head plant
B.
Medium head plant. (60m to 300 m.)
C.
Low head plant. ( > 60m.)
•
( < 300 m.)
CLASSIFICATION BASED ON WATER CONDITION.
A.
Flow of water plant.
B.
Storage of water plant.
C.
Pump storage water plant.
Many creeks and rivers are permanent, they never dry up, and these are the most suitable for micro-hydro power production. Micro hydro turbine could be a water-wheel turbine, Pelton wheel. (most common turbine). Others : Turgo, Cross-flow and various axial flow turbines.
Head ◦ Water must fall from a higher elevation to a lower one to release its stored energy. ◦ The difference between these elevations (the water levels in the forebay and the tailbay) is called head.
Dams: Are of three categories. ◦ high-head (800 or more feet) ◦ medium-head (100 to 800 feet) ◦ low-head (less than 100 feet)
Power
is
proportional
to
the
product
of
head x flow http://www.wapa.gov/crsp/info/harhydro.htm
27
Large-hydro ◦ More than 100 MW feeding into a large electricity grid.
Medium-hydro ◦ 15 - 100 MW usually feeding a grid.
Small-hydro ◦ 1 - 15 MW - usually feeding into a grid.
Mini-hydro ◦ Above 100 kW, but below 1 MW.
Micro-hydro ◦ From 5kW up to 100 kW ◦ Usually provided power for a small community or rural industry in remote areas away from the grid.
Pico-hydro ◦ From a few hundred watts up to 5kW. ◦ Remote areas away from the grid.
•
Classification based on operation.
A.
Manual plant.
B.
Automatic plant.
•
Classification based on type of load.
A.
B.
Base load plant.
Peak load plant.
1.
Reservoir.
2.
Catchments area.
3.
Dam.
(a) Earthen dam.
(b) Masonry dam.
(c) Concrete dam.
4. Spill ways.
5. Screen.
6. Fore bay or Intake.
7. Tunnel.
8. Penstock or pipe line.
9. Surge tank.
10. Draft tube.
11. Tail race.
12. Fish passes.
13. Turbine.
1.High head schemes.
2.Medium head schemes.
3.Low head schemes.
1.High head schemes. (Impulse turbine, pelton wheel)
2.Medium head schemes. (reaction turbine )
3.Low head schemes. (propeller turbine )
Used in remote locations in northern Canada
base load capacity
◦ Water flows downhill during day/peak periods
Typical efficiency of 70 – 85%Completed 1967 Capacity – 324 MW ◦ Two 162 MW units.
Purpose – energy storage
◦ Water pumped uphill at night Low usage – excess
36
There is substantial increase in peak load capacity of plant at comparatively low capital cost. There is an improvement in the load factor of plant. Load on hydro-electrical plant remains uniform.
Name
Country
Year
Max Generation
Annual Production
Three Gorges
China
2009
18,200 MW
Itaipú
Brazil/Paraguay
1983
12,600 MW
93.4 TW-hrs
Guri
Venezuela
1986
10,200 MW
46 TW-hrs
Grand Coulee
United States
1942/80
6,809 MW
22.6 TW-hrs
Sayano Shushenskaya
Russia
1983
6,400 MW
Robert-Bourassa
Canada
1981
5,616 MW
Churchill Falls
Canada
1971
5,429 MW
35 TW-hrs
Iron Gates
Romania/Serbia
1970
2,280 MW
11.3 TW-hrs
Ranked by maximum power.
“Hydroelectricity,” Wikipedia.org
38
Arch Gravity Buttress Embankment or Earth
FIRST ELEMENT :-
DAMS
Arch shape gives strength Less material (cheaper) Narrow sites Need strong abutments
Weight holds dam in place. Lots of concrete. (expensive)
Face is held up by a series of supports. Flat or curved face.
Boyle, Renewable Energy, 2nd edition, Oxford University Press, 2003
44
Head Pressure
Impulse
High
Medium
Low
Pelton Turgo Multi-jet Pelton
Crossflow Turgo Multi-jet Pelton
Crossflow
Francis Pump-as-Turbine
Propeller Kaplan
Reaction
Boyle, Renewable Energy, 2nd edition, Oxford University Press, 2003
Francis Turbine Kaplan Turbine Pelton Turbine Turgo Turbine New Designs
Specific speed; high specific speed is essential where head is low. Rotational speed; Efficiency; Part of load operation; Cavitations; Disposition of turbine shaft; Head;
Reaction Turbines ◦ ◦ ◦ ◦
Derive power from pressure drop across turbine. Totally immersed in water. Angular & linear motion converted to shaft power. Propeller, Francis, and Kaplan turbines
Impulse Turbines ◦ Convert kinetic energy of water jet hitting buckets. ◦ No pressure drop across turbines. ◦ Pelton, Turgo, and crossflow turbines
Uses the velocity of the water to move the runner and discharges to atmospheric pressure. The water stream hits each bucket on the runner. High head, low flow applications. Types : Pelton turbine, Turgo turbine
Uses the velocity of the water to move the runner and discharges to atmospheric pressure.
The water stream hits each bucket on the runner.
No suction downside, water flows out through turbine housing after hitting. High head, low flow applications. Types : Pelton wheel, Cross Flow
Combined action of pressure and moving water. Runner placed directly in the water stream flowing over the blades rather than striking each individually. Lower head and higher flows than compared with the impulse turbines.
It is run-of-river power plant. Do not worry about the turbidity of water. There is no danger of cavitations. It is simple to construct, repaired and maintenance.
The slow rotation of chain turbine leads to high speed ratios when connect to generator at 600 rpm – 1500 rpm. This chain turbine operation is very noisy. Structure of turbine is very big.
Nozzles direct forceful streams of water against a series of spoon-shaped buckets mounted around the edge of a wheel. Each bucket reverses the flow of water and this impulse spins the turbine.
Suited for high head, low flow sites. The largest units can be up to 200 MW. Can operate with heads as small as 15 meters and as high as 1,800 meters.
Kaplan Francis Pelton Turgo
2 10 50 50
< < < <
H < 40 H < 350 H < 1300 H < 250
(where H = head in meters)
Constr uction of Turbine.
Inlet Outlet Impulse turbine for High head plant.
Medium head plant
Medium head plant
Propeller turbine for low head plant.
Its function is to prevent sudden increase of pressure in the supply line or in the penstock. It is placed as near as possible to the turbine. Water hammer Due to the variation in the demand of water supply according to load, the turbine gates get closed suddenly which cause increase in pressure. This is known as water hammer.
Tailraces:-
What is the function of Spill ways?
1.
The plant is simple in construction ,robust and required low maintenance.
2.
It can be put in the service instantly.
3.
It can respond to changing loads without any difficulty.
4.
There are no stand by losses.
5.
The running charges are very small.
6.
No fuels is burnt.
7.
The plant is quite neat and clean.
8.
The water after running the turbine can be used for irrigation and other purpose.
1.
The capital cost of generators, civil engineering work etc is high.
2.
High cost of transmission lines.
3.
Long dry seasons may effect the delivery of power.
1.
sufficient quantity of water at a reasonable head should be available.
2.
The site should allow for strong foundations with minimum cost.
3.
There should be no possibility of future source of leakage of water.
4.
The selected site should be accessible easily.
5.
There should be possibility of stream diversion during construction period.
6.
The reservoir to be constructed should have large catchments area, so that the water in it should never fall below the minimum level.
Environmental Benefits of Hydro power plant. • No operational greenhouse gas emissions. Non-environmental benefits – flood control, irrigation, transportation, fisheries and tourism.
The loss of land under the reservoir. Interference with the transport of sediment by the dam. Problems associated with the reservoir.
◦ Climatic and seismic effects. ◦ Impact on aquatic ecosystems, flora and fauna.
A large area is taken up in the form of a reservoir in case of large dams.
This leads to inundation of fertile alluvial rich soil in the flood plains, forests and even mineral deposits and the potential drowning of archeological sites.
Power per area ratio is evaluated to quantify this impact. Usually ratios lesser than 5 KW per hectare implies that the plant needs more land area than competing renewable resources. However this is only an empirical relation.
Capture of sediment decreases the fertility downstream as a long term effect. It also leads to deprivation of sand to beaches in coastal areas. If the water is diverted out of the basin, there might be salt water intrusion into the inland from the ocean, as the previous balance between this salt water and upstream fresh water in altered. It may lead to changes in the ecology of the estuary area and lead to decrease in agricultural productivity.
It is believed that large reservoirs induce have the potential to induce earthquakes.
In tropics, existence of man-made lakes decreases the convective activity and reduces cloud cover. In temperate regions, fog forms over the lake and along the shores when the temperature falls to zero and thus increases humidity in the nearby area.
P g Q H P 10 Q H
P = power in kilowatts (kW) g = gravitational acceleration (9.81 m/s2) = turbo-generator efficiency (0
Non –toxic dust Sulphurous anhydride Carbon monoxide Nitrogen dioxide Soot (fly ash) Hydrogen sulphide Pollution can be define as the contamination of soil, air and water with undesirable amount of material and heat.
Acid rain; the rain which contain acid as its constituents, brings all the acid down from high above the environment.
Contaminant; it is the another name of pollution. It is undesirable substances which may be physical, chemical or biological.
Pollutant; these are undesirable substances
present in the environment these can be NO2, SO2, CO2,smoke,salt, bacteria.
Greater reliability of supply to the consumers. Avoid complete shut down. The overall cost of energy per unit of an interconnected system is less. There is a more effective use of transmission line facilities. Less capital investment required. Less expenses on supervision, operation and maintenance.
Due to limited generating capacity diesel power stations is not suitable for base load plants. Nuclear power stations is not suitable for peak load plants.
Incremental rate curve shows that as output power increases, cost of plant also increases.
Flat rate tariff; by estimating load factor and diversity factor for various uses of electricity, we may merge the equitable contributation to the fixed charge of a particular class of consumers with each KWH consumption, the resultant tariff is a Flat rate tariff .
Two part tariff; total charge is split into two components i.e. a fixed charge depend upon the maximum demand and a variable charge based upon the energy consumption.
Block rate tariff; using this tariff, the fixed charge is merged into the unit charge for one or two blocks of consumption, all units in excess being charged at low unit rate. Maximum demand tariff; these tariff differ from two part tariff only in the sense that maximum demand is actually measured by a demand indicator instead of assessing it merely on the bases of ratable value. Power factor tariff; power factor tariffs are devised to make a distinction between overall charge per unit to be recovered from two types of consumers, one having a good power factor and the other having a poor power factor.
Wind power plants is least reliable, and hydro power plants are most reliable. The power output from hydro power plant depends on discharge, head and system efficiency. The power output from hydro power plant in KW is given by 0.736Qwhή/75 In hydro power plant the operating cost is low but the initial cost is high. Gross head of an hydro power station is the difference of water level between in the storage and tail race.
The flow duration curve at a given head of hydro power plant is used to determine total power available at the site. The draft tube is provided to increase the acting head on the water wheel. For low head power plants kaplan turbines are used. For high head and low discharge power plants pelton wheel turbines are used. 1.25 The specific speed (Ns) of a turbine is given by Ns=N√P/H The specific speed (Ns) of a turbine is the speed at which the turbine develops unit horse power at unit head.
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