What is steam turbine description and characteristics. This governing is made by getting down the pressure of the steam. Impulse turbines, reaction turbines, the impulse principle, the reaction principle, the impulse turbine, compounding of impulse turbine. Taylor 1996 goes on to describe turbine glands, nozzles, bearings, lubrication, turbine control and gearing. Three basic types of steam turbine are used to generate power as a byproduct of process or exhaust steamml. The steam possessesa very high velocity at the end of the expansion, and the enthalpy decreases as. Steam nozzles and types nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop.
Sep 14, 2018 herewith we have shared the steam boilers, engines, nozzle, turbines mechanical mcqs pdf mechanical engineering multiple choice questions and answers pdf. Rotor means which part rotate and stator means which part is fixed. Extraction condensing steam turbine the extraction turbine. In this type of steam turbine the rotor spins due to the force, or the direct push of steam on the blades.
Pdf the present work investigates the feasibility of a methodolody for the. The steam from the first set of blades then passes to another set of nozzles and then blades and so on along the rotor shaft until it is finally exhausted. The smallest section of the nozzle is called throat. Steam turbines consist not only rotating blades called as rotor but also static blades called as stator. It converts a part of the energy of high temperature and high pressure steam into mechanical energy or shaft work. Two types of modern steam turbines and their mechanical. The flow of steam through nozzles may be takenas adiabatic expansion. Both of these steam turbine types have their own operating schemes and benefits which are described here in detail. Process of complete expansion of steam takes place in stationary nozzle and the velocity energy is. In principle, the impulse steam turbine consists of a casing containing stationary steam nozzles and a rotor with moving or rotating buckets. Working principle of steam turbine depends on the dynamic action of steam. Steam boilers, engines, nozzle, turbines mechanical mcqs pdf.
Based on operating principle the steam turbine is classified as two types. Historically, the first steam turbine of which we have proof was built by heron of alexandria around 175 bc, which consisted of a metal sphere with two nozzles at their poles and oriented in the same direction where the steam escaped. Most industrial installations are in the range 15 mw e. Supersaturated flow or meta stable flow in nozzles. Nozzle is a duct of varying crosssectional area in which the velocity increases with the corresponding drop in pressure. A more modern version of this car was produced some time in the late 18th. This type of nozzle is widely used these days in various types of steam turbines. What is a turbine a turbine is a rotary mechanical device that extracts energy from a fast moving flow of water, steam, gas, air, or other fluid and converts it into useful work. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. This is the operating principle of all steam turbines, although the arrangements may vary considerably. This divides the velocity drop across the stage into several smaller drops.
The flow of steam through nozzles may be taken as adiabatic expansion. There are two types of modern steam turbines impulse turbine in this type of turbine the steam nozzles direct superheated steam at the buckets of rotor blades, the impact of this causes the rotor to rotate. In the efficient use of energy second edition, 1982. Normally the high pressure and intermediate pressure stages of a steam turbine are of the impulse type. Oct 15, 2016 steam nozzles and types nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. In this steam turbines books section you will find handbooks training material and slides related to steam turbine auxiliaries, design and operation and maintenance. Unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure ratio,supersaturated flow. Nozzle is a duct by flowing through which the velocity of a fluid increases at the expense of pressure drop. If the steam available at the inlet has only kinetic energy, the turbine is called impulse turbine. The available energy of steam is first changed into kinetic energy, and this kinetic energy is then transformed into mechanical work. Nozzle is the stator part of turbine means it is fixed part. With an equal division of steam the two reaction effects balance and cancel one another. The narrowest section of the cd nozzle is called throat.
The main distinction is the manner in which the steam is expanded as it passes through the. With this arrangement steam enters at the centre of the shaft and flows along in opposite directions. These are manufactured for outputs from 50 kw e to 30 mw e. What are the effects of friction on the flow through a steam nozzle. Steam turbine working principle and types of steam turbine. Steam turbines were also described by the italian giovanni branca 1629 and john wilkins in england 1648. These three are called a back pressure steam turbine, an extraction steam turbine and a condensing steam turbine. Steam nozzles flow of steam through nozzles the expansion of steam through a nozzle is considered as adiabatic there is no work done during flow of steam.
The best definition for a turbine one might provide is that the conversion of steams heat to mechanical work, that is finished on a rotating output shaft. Steam then leaves the turbine and is utilized in other parts. Two general types impulse turbines relying on velocity of jet. This manual does not for designing steam turbine and the related parts. The turbine selected depends largely on the site conditions. Since then turbines based on these principles have evolved in parallel and in fact merged to some degree. The condensing type, which is typical of larger turbines, is subject to attracting force due to vacuum pressure on the exhaust side.
In this type, the total pressure drop expansion of the steam take place only in the first nozzle ring. Isentropic expansion expansion in a steam turbine steam from the boiler. Steam turbine two types of steam turbines were considered with an fem analysis, those being back pressure type and condensing type. There are two classical types of turbine stage designs. Purpose this manual can be used for preliminary selection, steam and cooling water planning for steam turbines in basic and detail engineering stages. Function of nozzle applications and types flow through. If the steam available at the inlet has kinetic energy as well pressure energy, the turbine is called reaction turbine. What are the various types of nozzles and their functions. Expansion of steam takes place partly in nozzle stator and partly in rotor. The variation of steam pressure in the nozzle depends upon the velocity, specific volume and dryness fraction of steam. Steam generator, turbine, pump, nozzle, throttling, the mathematical expression of the 1st law for a closed system, examples of closed.
Each type will suit a different configuration of plant. All steam turbines can be classified into two categories. In order to match steam production to heat demand, there are three types of steam turbine in common use for chp plants. Just as with pumps, there are two basic types of turbine. The main distinction is the manner in which the steam is expanded as it passes through the turbine. The most common types of blade fastenings in steam turbines were shown in figure 7 under columns a and b. The devices described by taqi aldin and wilkins are today known as steam jacks. The nozzle is so shaped that it will perform this conversion of energy with minimum loss.
The specific type of turbine to be used in a power plant is not selected until all operational studies and cost estimates are complete. Furthermore, socalled paretotype genetic algorithms are of particular interest. While steam expands in turbines, theoretically the entropy a remains constant b increases c decreases. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors. The velocity of steam is twice as fast as the velocity of blade. There are two general types of steam turbine designs. In noncondensing turbines or backpressure turbines, steam exhausts at a pressure greater than atmospheric. The operation of steam turbine completely depends on the dynamic action of the steam expanding in. Variable from little to massive, the turbines are created in a very big range of power capacities. This highvelocity steam produces dynamic pressure on the blades in which blades and shaft both start to rotate in the same direction.
Impulse turbine and reaction turbineprinciple, working and. Definition a steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft. Steam turbine types steam turbine types based on blade geometry and energy conversion process are. For gases, we usually call them wind turbines, gas turbines, or steam turbines, depending on the type of gas being used. Blades, fastened in this manner, have to conform in their. A velocitycompounded impulse stage consist of a row of fixed nozzles followed by two or more rows of moving blades and fixed blades without expansion. Compounding of steam turbines is the strategy in which energy from the steam is extracted in a number of stages rather than a single stage in a turbine. In 1672 an impulse steam turbine driven car was designed by ferdinand verbiest. Types of steam turbines chemical engineering world. The basic idea of an impulse turbine is that a jet of steam from a fixed nozzle pushes against the rotor blades and impels them forward. Outwardly turbines of both types appear identical and, in. Steam turbines may be classified into different categories depending on their construction, working pressures, size and many other parameters. It is very useful for all kind of gate, ssc, ese and other competitive examinations.
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