Runner with bucket: – runner of Pelton wheel consists of a circular disc on Governing mechanism: – speed of turbine runner is required to be. This speed should also conforms to the power supply frequency. So this mechanism acts as a speed governing mechanism of Pelton wheel. Presentation on:Governing of Pelton WheelTurbine pump with oil sump Relay or control valve Servomotor with spear rod and spear Deflector mechanism.
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We think you have liked this presentation. If you wish to download it, please recommend it to your friends in any social system. Share buttons are mechamism little bit lower. Published by Valerie Posy Martin Modified over 3 years ago. Availability of water Water storage Water head Distance from load centre Accessibility of site Water pollution Sedimentation Large catchment area Availability of land.
In other words it is study of hydrological cycle, in which the water rises by evaporation from sea, is carried over land, where it falls as precipitation and then rises again by evaporation or transpiration or flows back to sea. Rainfall or Precipitation is defined as the total condensation of moisture that reach the earth in any form. It is defined as that part of the precipitation which is available goverhing stream flow. It is the graphical representation between discharge and flow with time.
Hydrograph provides following information: The discharge at any time during the period under consideration.
The maximum and minimum run-off during period.
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The average run-off during the period. Total volume of discharge upto any time, given by the area under the curve upto the time. It gives relation between flows and lengths of time during which they are available. The area under flow-duration curve represents the total quantity of run-off during the period. A flow-duration curve may be used for determination of minimum and maximum condition of flow. Goferning flow duration curve can be mechajism upon by storing water on the upstream side and using it during off peak period.
It is curve which indicates the total volume of run-off in m3 upto a certain time.
Presentation on:Governing of Pelton WheelTurbine
This curve is obtained from records of average monthly flows. The slope of this curve at any point gives the rate of flow at that time. If rainfall is uniform throughout the year, the mass curve would be straight line with uniform slope.
These curves are used in determination of the capacity ;elton storage reservoir. In most of the streams the flow in excess during one period and deficient during another period for its regulation artificial storage is needed. In case power plant is away from reservoir, a small pond is required near to plant in order to meet the hourly changes in power governinh. Penstock Gurbine and Gates. It is temporary regulating reservoir. It store water when load is light and supplied same water mefhanism peak period.
It discharge the overflow water to downstream mechanisj when the reservoir is full. This sudden rise of pressure in penstock known as water hammering. It prevents debris from water. It also trapezoidal in shape with wide base. It is suitable for mountainous regions.
Excess water above the full reservoir level flows over the crest in the form of rolling sheet of water. The flow of water in side channel is either used as a cannel or it meets to river. There may be some natural depression or saddle on the periphery of the reservoir basin away from the dam.
Its lower end is turned at right angle and horizontally taken out of dam. The crest of spillway is kept at full reservoir level. If water rises above full level of reservoir water enters into spillway and discharge.
Vertical bell shaped draft tube: Based on nature of load Base load plants Peak load plants. Based on quantity of water available Run-off river plants without pondage. Run-off river plants with pondage. No surge tank required. Francis, Propeller or Kaplan turbine are employed. Surge tank is built just before the valve house so that the severity of water hammering is reduced. Peak load plants The plants used to supply the peak load of the system corresponding peoton the load curve are called peak load plants.
The plants are located that the water is taken from the river directly, and no pondage or storage is possible. Such plants are called the Run-off river plants without pondage. No control on flow of water.
Capital cost required is low. Storage and pondage is available. Useful on parts of load curve. Can be used as base or peak load plants. It constructed if rainfall occurs only for few months in a year and the remainder periods are dry.
These type petlon plants are suitable as peak load plants at locations where there is a storage of water since these plants are designed such that it pumps back portion of its water supply petlon tail race to head race during non- peak periods. The water turbines are simple in construction, highly governign in operation, easily controllable and pick up the load in a short time. Tangential or peripheral turbines: 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. Pelton wheel, Cross Flow e. Runner placed directly in the water stream flowing over the blades rather than striking each individually. Each bucket reverses the flow govefning water and this impulse spins the turbine.
The largest units can be up to MW. Can operate with heads as small as 15 meters and as high as 1, meters.
Guide vanes direct the water tangentially to the runner. This radial flow acts on the runner vanes, causing the runner to spin. The guide vanes or wicket gate may be adjustable to allow efficient turbine operation for a range of water flow conditions.
Water is directed tangentially, through the gate, and spirals on to a propeller shaped runner, causing it turbjne spin. The outlet is a specially shaped draft tube that helps decelerate the water and recover kinetic energy. For this system requires a oil sump to store oil and mechznism pump to regulate the supply. Tjrbine of oil pump is to pressurize the oil. It is also called as control valve or distributor.
It receives the pressurized oil from pump which is diverted towards the ports connected to pipe Pelon or pipe B. Through these pipes the oil is transferred to corresponding sides of double acting servomotor cylinder. Simultaneously, the oil will be returned from the servomotor from the opposite pipe to the sump.
It is double acting cylinder which acts as hydraulic actuator. It receives turgine from relay valve say through pipe A. The piston of the turbins will be displaced towards left, thus forcing the oil through the pipe B into the relay valve and finally to oil sump.
It will Simultaneously more the spear valve to the left and increase the area of flow through the nozzle. Spear valve controls the flow area of the nozzle. It is directly connected to the piston of tirbine cylinder Governor and linkages: A centrifugal governor is used as the measuring element of turine closed loop control system.
It is driven by the turbine shaft through bevel gears. The sleeve of the governor is connected through linkages to relay valve. The movement of sleeve is transferred through the lever to more the piston rod of relay valve. It is a circular ring having guide vanes pivoted at a point through the levers and links.
Therefore when the regulator ring is rotated about its axis, all the guide vane would turn about their pivots. Due to turning of guide vanes the space between two consecutive guide vanes would change. Space between guide vanes will increase in one direction of rotation of regulating ring and space will decrease in its opposite direction of rotation.
It connects the regulating ring to relay cylinder through the various linkages as shown in fig. It can be seen by this mechanism, the linear motion of servomotor piston is converted into rotary motion mechanis regulating ring. An alternate arrangement providing the rotary motion to regulating ring by using two servomotors. This mechanism gives better performance since the force required for operation of Francis turbine guide vanes is much more compared to Pelton turbine. The governing achieved by changing the guide vane angles.
Therefore, a separate servomotor is provided to operate the runner blades which are few in number. Due to control of both guide and moving vanes, the Kaplan turbine gives better efficiency over wide range of load as compared to Francis turbine. governijg
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