Governing of steam turbine is the procedure of controlling the flow rate of steam to a steam turbine so as to maintain the speed of the turbine fairly constant irrespective of load on the turbine. To maximize power plant efficiency, aerodynamic and steam leakage losses in the turbine steam path must be minimized in both the rotating and stationary components. Thermal engineering pdf of rk rajput for mechanical. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. In the nozzle control governing, the steam supply from the main valve is divided into two, three, or more lines. First let us understand what it means, throttle governing.
Turbine governing the steam flow through the control valve is proportional to the. Unit iii unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure ratio,supersaturated flow. The turbine blades are made up of chromiumnickel steel or 17 cr ni steel. The combined flow characteristics of given valve overlap degree were obtained for a 600 mw steam turbine. Owing to the high velocity, the residence time of steam in the steam nozzle is small, and there may not be. Types of steam turbines chemical engineering world. Nozzles are used to guide the steam to hit the moving blades and to convert the pressure energy into the kinetic energy. During such operation, bypass valves are opened and fresh steam is introduced into the later stages of the. The velocity of the steam exiting the nozzles is the major factor in the tendency to accelerate the turbine rotor. Rotor means which part rotate and stator means which part is fixed. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors.
Design parameters steam turbine mechanical engineering. Turbines with bypass governing in which steam besides being fed to the first stage is also directly led to one, two or even three. What is meant by super saturation in steam nozzles. Steam turbines have a set of rotating blades and a row of fixed half moon blades. Lprimlife for rotors with bladeattachment cracking suitable for use with all rotor designs, lprimlife developed on behalf of epri, is a software code to assess the life of steam turbine rotors with bladeattachment cracking. Occasionally the turbine is overloaded for short durations. Steam turbine governing and its mechanism ece tutorials. Steam turbine governing steam turbine governing is the procedure of controlling the flow rate of steam into a steam turbine so as to maintain its speed of rotation as constant. The typical main turbine in nuclear power plants, in which steam expands from pressures about 6 mpa to pressures about 0. Flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure. Friction exists between the steam and the sides of the nozzle.
Before reaching the turbine, the fluids pressure head is changed to velocity head by accelerating the fluid with a nozzle. Because of throttling of the steam at the inlet of the turbine there are important throttling losses. Consider steam turbine drives for rotating equipment steam turbines are well suited as prime movers for driving boiler feedwater pumps, forced or induceddraft fans, blowers, air compressors, and other rotating equipment. Governing system steam turbine pdf gas technologies energy. The steam has a very high velocity at the end of the expansion, and the enthalpy decreases as expansion takes place. Steam turbines classification, governing equations and. Nozzle governing of steam turbine animated video 24. There is no pressure change of the fluid or gas in the turbine blades the moving blades, as in the case of a steam or gas turbine, all the pressure drop takes place in the stationary blades the nozzles.
The flow of steam through nozzles may be regarded as adiabatic expansion. Nozzle is the stator part of turbine means it is fixed part. Nema standards publication sm 241991 revises and supersedes the nema standards publi cation land based steam turbine generator sets 0 to 33,000 kw, sm 241985. The magnitude of each component was determined as 1. Steam enters a group of nozzles of a steam turbine at 12 bar and 2200 c and leaves at 1. Steam turbine governing gas technologies mechanical. Steam turbine and steam nozzle interview question and answers steam turbine and steam nozzle interview, viva, oral question and answers 1.
Moving blades work due to differential pressure of steam between front and at behind of. Throttle governing is the most widely used method in steam turbine governing for smaller turbines where the steam flow is less. In the case of small impulse turbine, the nozzles are located in the lower half of the casing. Pdf study on valve management of deh for steam turbine. The parts of a steam turbine may be thought of as being in four groupings. At full load, all the nozzles will be delivering steam at full pressure and the turbine. In turbines there are basically 2 part one is called rotor and another is known as stator. Governing stage steam turbine with nozzle regulation. In comparison to a conventional turbine arrangement consisting of control valve and several turbine stages, the control by nozzle sections substitutes for the control valve and the first turbine stage. Valve positioning must be accurate for adequate control ofturbine generatorload when syncbronized and speed during runup and. Pdf power plant lecture notes chapter4 steam turbine. Owing to the high velocity, the residence time of steam in the steam nozzle. User needs have been considered throughout the development of this standard.
Throttle regulation this governing is made by getting down the pressure of the steam, this is made. So the use of nozzle governing is limited to small turbines. Since no regulation to the pressure is applied, the advantage of this method lies in the exploitation of full boiler pressure and temperature. The actuator ofalarge turbine steam valve must generate large forces that are required10 overcome forces exerted by the steamflow and friction in the valve stem seal. A ge gas turbine is a fully integrated design consisting of stationary and rotating mechanical, fluid, thermal, and electrical systems. Steam turbine basic parts mechanical engineering site. In actual turbine, nozzle governing is applied only to the first stage whereas the subsequent stages remain unaffected. This service generally calls for a backpressure noncondensing steam turbine. Unit 4 flow through nozzles velocity and heat drop, mass discharge through a nozzle, critical pressure ratio and its significance, effect of friction, nozzle efficiency, supersaturated flow, design pressure ratio. The influence of overlap degree research on nozzle governing.
What is steam turbine description and characteristics. In this article we discussed about the classification of steam turbine according to their usages and operation condition. With a poor governing system, these smaller, less abrupt, load changes can still result in. The control value position will be adjusted to allow the required steam for turbine operation. The main use of steam nozzle in steam turbines is to produce a jet of steam. Consider steam turbine drives for rotating equipment. Figure 2 shows the mechanism of nozzle governing applied to steam turbines. Top 40 steam nozzle mechanical technical interview questions and answers for fresher experienced. Governing system steam turbine pdf free download as pdf file. Based on the model, steam particle flows in the governing stage cascade of a supercritical steam turbine are systematically investigated and the influence of oblique stator on the aerodynamic. The turbine s performance, as well as the performance of each component within the turbine. An electronic governing system can provide instantaneous data on the turbine s performance and speed while requiring minimal power and eliminating cumbersome mechanical attachments. The variation in load during the operation of a steam turbine can have a significant impact on its performance.
Steam turbine governing is the procedure of controlling the flow rate of steam to a steam turbine. The steam turbine develops 220 kw with a specific steam consumption of. Although throttling is an isenthalpic process, the enthalpy drop available for work in the turbine is reduced, because this causes an increase in vapor quality of outlet steam. In reaction turbine, there is no nozzle to convert steam energy to mechanical energy. In nozzle governing the flow rate of steam is regulated by opening. Steam consumption of steam turbine is depending to required output power and efficiency of the turbine. In nozzle governing the flow rate of steam is regulated by opening and shutting of sets of nozzles rather than regulating its pressure.
Steam turbine and steam nozzle interview question and. Turbines with throttle governing in which fresh steam esters through one or more simultaneously operated throttle valves. Uncategories thermal engineering pdf of rk rajput for mechanical engineering students. What is the difference between throttle governing and. Anuniverse 22 nozzle governing of steam turbine youtube. Efficiency will depend on turbine size or rotor diameter, blade. Understanding and preventing steam turbine overspeeds by william e. The best definition for a turbine one might provide is that the conversion of steam s heat to mechanical work, that is finished on a rotating output shaft. Throttle governing of steam turbine pdf jewellery trendz. Variable from little to massive, the turbines are created in a very big range of power capacities. The nozzle section control is modeled by a throttled and an unthrottled mass flow, each led through the steam turbine. In this case of governing mechanism, the mass flow rate is controlled by throttling the steam by means of control value. Mechanical engineering channel anuniverse 22 has started to stand on the shoulders of engineering giants and now, it is a place to hang out to learn the basics of mechanical engineering.
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