The inlet velocity triangle the outlet velocity triangle at the inlet there is no component of absolute velocity in the direction of rotation. The nozzle angles for the first two impulse turbines are the same. Apr 25, 2016 impulse turbine works on the basic principle of impulse. The inlet angle of the reaction stages are the same as the nozzle angles of the impulse stage 3.
In velocity compounding of an impulse turbine the expansion of steam takes place in a nozzle or a set of nozzles from the boiler pressure to the condenser pressure. Draw the velocity diagram of impulse turbine and find the work done on the blade, blade efficiency derive the expression for condition for maximum efficiency of an impulse turbine. Pressurevelocity compounding curtis turbine curtis turbine pressurevelocity compounding. The fact that the pressure does not drop across the moving blades is the distinguishing feature of the impulse. This is done to reduce the rotational speed of the impulse turbine to. Velocity triangles for turbine and compressor design. The most frequently used or proposed selfrectifying air turbines are the wells turbine and the impulse turbine, both of axialflow type. Each stage consists of a nozzle and blade row where the kinetic energy of the jet is absorbed into the turbine rotor as useful work. Velocity compounded impulse turbine contd velocity compounded impulse turbine from me 430 at the city college of new york, cuny. Another impulse turbine is the pressure compound or ratteau turbine.
In the reaction turbine, first the steam flows through the guide mechanism. It follows that the magnitude of the velocity remains unchanged. Basics of impulse turbine in impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor. Hiried power plant engineering multiple choice questions.
Turbine system turbine bearing mechanical free 30day. The air that leaves the moving blades enters the next set of nozzles where the enthalpy decreases further, and the velocity is. Pressure compounding or rateau stage in a pressure. In the impulse turbine, the gases will be expanded in the nozzle and passed over to the moving blades.
The mean peripheral velocity of blade is 400 ms and the blades are symmetrical. Turbines a turbine is a rotary engine that exerts energy from a fluid flow and converts it into useful work. Velocity compounded impulse turbine contd velocity. Pressure velocity compounding curtis turbine curtis turbine pressure velocity compounding. In contrast to water turbines where the total head is extracted in a single runner see above, the steam velocities obtained from the enthalpy drop between steam. Oct 22, 2014 impulse turbine principle 11 nozzle steam chest rotor khit, guntur 12. This is also known as a rateau turbine, after its inventor.
This means the structure of anything from motorways. Steam turbine training governing system training course. The velocity compounded impulse turbine was first proposed by c. When the steam passes through the moving blades the velocity drops but the pressure remains the same.
Impulse turbines are simple devices where the steam expands in or through the nozzle, and the heat released through the pressure drop associated with the nozzle or comparable device imparts velocity to the steam. Impulse turbine efficiency calculation methods with. Steam turbines their construction, selection and operation pdf. Velocity compounding steam is expanded through a stationary nozzle from the boiler or. The fixed blade angles of the two reaction turbines equal to the given inlet angle. In curtis turbine steam leaving the nozzle is utilized in both rows of moving blades instead of single raw as in the delaval turbine. The construction work montreal city construction is the process of developing a structure or groundwork.
What is the difference between an impulse and a reaction turbine. One of the most popular example of impulse turbine is pelton wheel. A pelton turbine develops 2000 kw under a head of 100 m and with an overall efficiency of 85%. The rotor blades can be recognized by their shape, which is symmetrical and have entrance and exit angles around 20 o. In fact, a series of velocitycompounded impulse stages is called a pressurevelocity. 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. Velocity compounding curtis impulse turbine 23 pressure compounding. Velocity compounded impulse turbine will not give less speed. A turbine was investigated by various methods of calculating its efficiency. The cbt also covers steam turbines and the governing system in detail and includes woodwardtype governor operation. Impulse turbine a turbine in which fluid is deflected without a pressure drop in the blade passages. A velocity compounded impulse stage consist of a row of fixed nozzles followed by two or more rows of moving blades and fixed blades without expansion. Pressure compounding or rateau stage in a pressure compounded impulse turbine, called as rateau stage, the pressure drop is divided among different stages one single rateau stage consists of.
The velocity compounded impulse turbine was first proposed by c g curtis to solve the problem of. Impulse occurs when the direction of the fluid is changed with no pressure change. There are two basic types of turbines according to the mode of steam. Mechanical engineering gas turbines terms and definitions. The greater the task, it will take more to manufacture, so some construction could last half a month, and some could last a couple of years. A pressure compounded impulse stage is a row of fixed nozzles followed by a row of moving blades, with multiple stages for compounding.
The velocity of steam entering a simple impulse turbine is, and the nozzle angle is 20o. The force still comes from rate of change of momentum, but not as obviously as in the impulse turbine. A 1 and 2 only b 1 and 3 only c 2 and 3 only d 1, 2 and 3 key. A method for selecting impulse turbine wave energy to operate at a specified wave site power has been described. The project was based on an existing impulse turbine, a onestage turbine set in an organic rankine cycle with the working fluid being r245fa. Turbine 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. Design charts for impulse turbine wave energy extraction. Fundamentals of fluid mechanics chapter 12 pumps and turbines. The following section consists of steam nozzles and turbines questions on physics. Pdf power plant lecture notes chapter4 steam turbine. Pressure compounding, velocity compounding, pressurevelocity.
Steam turbine a steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. This divides the velocity drop across the stage into several smaller drops. Boyce, in combined cycle systems for nearzero emission power generation, 2012. Three main types of compounded impulse turbines are. What is velocity and pressure compounding in impulse turbine. Chaplin encyclopedia of life support systems eolss blades some potential energy is converted into kinetic energy but not as much as in the impulse turbine. Pressure compounded impulse turbine this involves splitting up of the whole pressure drop from the steam chest pressure to the condenser pressure into a series of smaller pressure drops across several stages of impulse turbine. Reaction occurs when the water is accelerated or decelerated over the vanes. Steam velocity at nozzle exit 600 ms nozzle angle 16 o mean blade velocity 120 ms exit angles. Low efficiency because blade speed ratio is less than the optimum value. The impulse turbine is the simplest type of turbine. The pressurevelocity compounding is a combination of the above two types of compounding. In the impulse turbine pressure drops and the velocity increases as the steam.
If the steam is to enter the blades without a shock, what will be the blade angles. Prefaceprefacepreface there have been significant developments and advances in the field of power plant engineering, computer applications on energy audit and management, environmental audit and management, human. When the jet of water strikes at the turbine blade with full of its speed, it generates a large force which used to rotate the turbine. May 26, 2019 difference between impulse and reaction turbine impulse turbine reaction turbine 1.
The steam turbine training and governing system training course covers the various turbine types and provides detailed classifications. In this turbine, the work is broken down into various stages. Thermal engineering ii imp qusts teii important questions. Impulse turbine impulse steam turbine stage consists as usual from stator which known as the nozzle and rotor or moving blades impulse turbine are characterized by the that most or all enthalpy and hence pressure drop occurs in the nozzle. Turbine casing is very simple and need not be very strong. A reaction stage is a row of fixed nozzles followed by a row of moving nozzles. The following particulars refer to a tworow velocity compounded impulse wheel. In fact, a series of velocity compounded impulse stages is called a pressure velocity compounded turbine. Impulse turbine and reaction turbineprinciple, working. Steam is a vapour used as a working substance in the operation of steam turbine. The charts developed here are of form suitable for sizing an impulse turbine to match a specified wave power for a desired air axial velocity and rotational speed. What are the advantages and disadvantages of velocity compounded impulse turbine.
The force is depends on the time interval and velocity of jet strikes the blades. Multiple choice questions on steam nozzles and turbines. The pressure velocity compounding is a combination of the above two types of compounding. Thermalengineeringbyrkrajput chapter19 steam turbine slideshare. Velocity compounded impulse turbine when the velocity energy produced by one set of fixed nozzles is unable to be efficiently converted into rotational motion by one set of moving blades then it is common to install a series of blades as shown in figure. The velocity compounded impulse turbine was first proposed by c g curtis to solve the problem of single stage impulse turbine for use of high pressure and temperature steam. Various methods of loss calculation were explored in the search for a method sufficiently accurate to. This turbine is a velocity compounded curtis stage having a pressure ratio of 221 and a design mach number from the nozzles of 2.
Numerous small drops result in a pressure compounded turbine. 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. The impulse generated in this procedure is used to provide the momentum to the blades. Curtis to solve the problems of a singlestage impulse turbine for use with high pressure and temperature steam. It is the most renowned example of impulse turbine. The impulse wheel carries two or three rows of moving blades. Steam turbine and steam nozzle interview question and answers. The velocitycompounded impulse turbine was first proposed by c. Pressure and velocity compounded impulse turbinespressure and velocity compounded impulse turbines. Us9410430b2 turbine apparatus with counterrotating blades. On this channel you can get education and knowledge for general issues and topics. Impulse stages may be either pressurecompounded, velocitycompounded, or pressurevelocity compounded.
Impulse and reaction turbine animation explain youtube. Only a small fraction of the overall pressure drop available in a turbine can be extracted in a single stage consisting of a set of stationary nozzles or vanes and moving blades or buckets. Steam turbine and steam nozzle interview question and. The moving blades are keyed to the turbine shaft and the fixed blades are fixed to the casing.
Impulse turbine works on the basic principle of impulse. Various methods of loss calculation were explored in the search for a. The cost of turbine is less because less number of stages. The steam after expanding through nozzles enters the first ring of moving blades at a high velocity. This turbine used to rotate the generator, which produces electric power.
Reaction turbine impulse turbines an impulse turbine uses the impact force of the steam jet on the blades to turn the shaft. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing work on the fluid. Oct 28, 2014 basics of impulse turbine in impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor. Pressure velocity compounded impulse turbine steam turbine in which the total pressure drop of steam is divided into stages and the velocity thus obtained in each stage is also compounded i. Note that the velocity diagram of the turbine differs from that of the compressor, in that the change in tangential. Impulse turbine and reaction turbine nuclear power. The force due to change of momentum causes the rotation of the turbine shaft. The velocity remain almost constant across the fixed blades. Simple indicates an elementary turbine without complications such as velocity compounding.
Velocity compounded impulse turbine the turbine in which the kinetic energy created by the expansion of gas in nozzles is absorbed in two or more rows of moving blades so as to reduce the speed of the turbine rotor. Compounding of steam turbines is the strategy in which energy from the steam is extracted in a. In the impulse turbine pressure drops and the velocity increases as the steam passes through the nozzles. This is why we call this type of turbine as impulse turbines. Impulse stages may be either pressure compounded, velocity compounded, or pressure velocity compounded. There are several distinctive types of axial turbine including both impulse and reaction, single and velocity compounded. It consists of only one set of nozzles at the inlet and a number of moving blades to the rotor and fixed blades to the casing at each stage. In the reaction turbine, the pressure change occurs in the runner itself at the same time that the force is exerted. Consists of two stage of nozzles followed by two rows of moving blades. The method in which energy from steam is extracted in more than single stage is called compounding.
A force is needed to do this and the reaction to this force acts on the vanes. In impulse turbine the steam flows through the nozzle and strike on the moving blades. Impulse turbine article about impulse turbine by the. Rateau steam turbine is a reaction steam turbine b velocity compounded impulse steam turbine c pressure compounded impulse steam turbine d pressure velocity compounded steam turbine ans. Multiple reaction stages divide the pressure drop between the steam inlet and exhaust. Classification pressure compounded impulse turbine velocity compounded. Hiried power plant engineering multiple choice questions and. The curtis stage turbine, as it came to be called, is composed of one stage of nozzles as the. A set of static guide vanes or nozzle vanes accelerates and adds swirl to the fluid and directs it to the next row of turbine blades mounted on a turbine rotor. Many turbines combine impulse and reaction, so that it is difficult to separate them conceptually. According to the newtons second law of motion,the direction of force in the blades, work done in the direction of motion of the blades, mathematically, axial thrust on the wheel is the velocity difference between inlet and outlet steams flow.
The rings of moving blades are separated by rings of fixed blades. The steam after expanding through nozzles enters the first ring of moving blades at a. Sep 23, 2015 on this channel you can get education and knowledge for general issues and topics. The picture shows combined velocity triangle of steam turbine. Impulse turbine and reaction turbineprinciple, working and. Ppt turbines powerpoint presentation free to download. Velocity compounded impulse turbine contd velocity compounded. Types of steam turbine a impulse turbine steam is expanded only in nozzles, and pressure at the outlet side of blades is equal to that at inlet side. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing. In this type, the total pressure drop expansion of the steam take place only in the first nozzle ring.
505 701 357 873 1216 867 303 10 1374 263 1146 700 1264 1392 107 85 1285 1149 1233 779 1009 1327 1436 437 391 1487 1356 1239 1296 272 605 452 369 1346 1439 769