Hydroelectric power-plant-and-hydro-machinery


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Hydroelectric power-plant-and-hydro-machinery

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Hydroelectric power-plant-and-hydro-machinery

  2. 2. HYDROELECTRIC POWER PLANTS      Moving water, such as a river or a waterfall, has mechanical energy. ‘Mechanical energy is the energy that is possessed by an object due to its motion or stored energy of position.’ This means that an object has mechanical energy if it’s in motion or has the potential to do work (the movement of matter from one location to another,) based on its position. The energy of motion is called kinetic energy and the stored energy of position is called potential energy. Water has both the ability and the potential to do work. Therefore, water contains mechanical energy (the ability to do work), kinetic energy (in moving water, the energy based on movement), and potential energy (the potential to do work.) The potential and kinetic/mechanical energy in water is harnessed by creating a system to efficiently process the water and create electricity from it. A hydroelectric power plant harnesses the energy found in moving or still water and converts it into electricity.
  3. 3. Hydropower to Electric Power Potential Energy Electrical Energy Electricity Kinetic Energy Mechanical Energy
  5. 5. Hydropower to Electric Power
  6. 6. How Hydropower Works    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.
  7. 7. How Hydropower Works (2)    A water turbine that cover 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.
  11. 11. Components of hydroelectric power plants 1) 2) 3) 4) 5) 6) 7) 8) 9) Catchment area Dam and Reservoir Penstock Trash rack Turbine Control gates Draft tube Forebay Surge tank
  12. 12. Understanding the components Catchment area The rain water falls on a large area called catchment area, gets collected in the form of streams and flows as runoff to plant site. DAM AND RESERVOIR The dam is usually built on a large river that has a drop in elevation, so as to use the forces of gravity to aid in the process of creating electricity. A dam is built to trap water, usually in a valley where there is an existing lake. An artificial storage reservoir is formed by constructing a dam across a river. The area behind the dam where water is stored is called the reservoir. The water there is called gravitational potential energy. The water is in a stored position above the rest of the dam facility so as to allow gravity to carry the water down to the turbines. Because this higher altitude is different than where the water would naturally be, the water is considered to be at an altered equilibrium. This results in gravitational potential energy, or, “the stored energy of position possessed by an object.” The water has the potential to do work because of the position it is in (above the turbines, in this case.)
  13. 13. PENSTOCK  It carries water from reservoir to the hydraulic turbine  The penstock is a long shaft that carries the water towards the turbines where the kinetic energy becomes mechanical energy. The force of the water is used to turn the turbines that turn the generator shaft.
  14. 14. Trash rack, Gates and anchorages    Trash rack prevent the entry of debris into the penstock. These debris would otherwise damage the gates, nozzles and turbine blades by erosion. Gates control and regulate the flow of water into the penstock. Anchorages prevent the movement of penstock due to dynamic forces at vertical and horizontal bends and on slopes.
  15. 15. Draft tube and tail race.   Draft tube is a kind of a diverging passage. Because of this shape, the water flows through this tube is decelerated and it comes out of tube with minimum kinetic energy. The exit of draft tube is submerged in tail race.
  16. 16. CONTROL GATES AND SPILLWAY   Control gates arrangement is provided with Spillways. Spillway is constructed to act as a safety valve. It discharge the overflow water to the down stream side when the reservoir is full. These are generally constructed of concrete and provided with water discharge opening, shut off by metal control gates. By changing the degree to which the gates are opened, the discharge of the head water to the tail race can be regulated inorder to maintain water level in reservoir.
  17. 17. SURGE TANK     It is a safety device. Whenever the electrical load on the generator drops down suddenly, the governor partially closes the gates which admits water flow to the turbine. Due to this sudden decrease in the rate of water flow to the turbine, there will be sudden increase of pressure in the penstock. This phenomenon results in hammering action called water hammer in the penstock. When turbine gates are suddenly opened to produce more power, there is a sudden rush of water through penstock and it might cause a vacuum in water flow system which might collapse penstock. Penstock withstands positive hammer and vacuum effects. SURGE TANK acts as a temporary reservoir. It helps in stabilizing the velocity and pressure in penstock and thereby saves penstock from getting damaged.
  18. 18. Turbine Classified
  19. 19. Impulse 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 
  20. 20. Pelton Turbine
  21. 21. Working of pelton wheel turbine
  22. 22. Reaction Turbines 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. 
  23. 23. Francis Turbine
  24. 24. Francis turbine
  25. 25. Working of Francis turbine
  26. 26. Water flow in a Francis turbine
  27. 27. Francis turbine
  28. 28. Parts of Francis turbine -Scroll casing  - Guide vane cascade  - Turbine covers  - Runner  - Shaft  - Bearing  - Shaft seal  - Regulating mechanism  - Draft tube 
  29. 29. Scroll casing  The water from the penstock is conducted through the scroll casing and distributed around the stay ring and the complete circumference of the guide vane cascade.
  30. 30. Guide vanes Guide vanes are adjustable. The vanes are shaped according to hydraulic design specifications and given a smooth surface finish. The bearings of the guide vane shafts are lubricated with oil or grease.
  31. 31. Runner It is attached to shaft which in turn is attached to generator shaft.  Due to action of water, it rotates and generates power. 
  32. 32. Kaplan Turbine
  34. 34. Francis and Kaplan turbine
  35. 35. Difference between Impulse and Reaction Turbines.  The difference between impulse and reaction turbines is impulse turbines convert the kinetic energy of a jet of water in air into movement by striking turbine buckets or blades - there is no pressure reduction as the water pressure is atmospheric on both sides of the impeller. The blades of a reaction turbine, on the other hand, are totally immersed in the flow of water, and the angular as well as linear momentum of the water is converted into shaft power - the pressure of water leaving the runner is reduced to atmospheric or lower