The pressure velocity compounding is a combination of the above two types of compounding. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing. It is the most renowned example of impulse turbine. To get the maximum energy transfer, the blades must rotate at about half the velocity of the gas jet velocity. The inlet angle of the reaction stages are the same as the nozzle angles of the impulse stage 3. The steam from the boiler which is usually in high pressure expands in the nozzle and the pressure energy changed into kinetic energy. A series of velocity compounded impulse stages is called a pressure velocity compounded turbine. In the reaction turbine, the pressure change occurs in the runner itself at the same time that the force is exerted. The relative velocity of steam entering the blades 3.
The force due to change of momentum causes the rotation of the turbine shaft. Pdf numerical analysis on impulse turbine for owc wave. Impulse turbine and reaction turbine nuclear power. Steam turbines turbine steam free 30day trial scribd. Ppt turbines powerpoint presentation free to download. In a steam turbine, highpressure steam from the boiler expands in a set of stationary blades or vanes or nozzles. Various methods of loss calculation were explored in the search for a. This type of compounding is known as the pressure compounding and the nozzle and blade arrangement for a pressure compounded impulse turbine is sketched. Effect of nozzle angle and silt parameters on erosion and. 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.
Neglecting the friction effects on the blades, calculate the tangential. 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. 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. Introduction 1turgo turbine is a medium head impulse turbine 15 300 m that operates in the head range where pelton and francis turbine overlap anagnostopoulos and papantonis, 2007. To study the working of impulse and reaction steam turbine. Velocity triangles for turbine and compressor design. University of texas at arlingtonmae 3183, measurements ii. The velocity of steam entering a simple impulse turbine is, and the nozzle angle is 20o. Steam turbine and steam nozzle interview question and. University of texas at arlingtonmae 3183, measurements ii laboratory impulse turbine 111 motivation the purpose of this experiment is to revise the concepts of turbine cycle, its practical implementation, improve the general understanding of how to calculate work, power, efficiency and effectiveness for open boundary thermomechanical systems. Velocity compounded impulse turbine contd velocity compounded impulse turbine from me 430 at the city college of new york, cuny.
The nozzle angle is 20, the mean blade velocity is 400 ms, and the inlet and outlet angle of blade are equal. Steam is expanded through a stationary nozzle from the boiler or inlet pressure to. Pressurevelocity compounding curtis turbine curtis turbine pressurevelocity compounding. The impulse turbine is recently employed for the bidirectional mechanical air power into electricity power. It has the advantage of reduced blade velocities, reduced steam velocities and equal work among stages, or equal work distribution among the stages as desired by the designer.
In 1987 a 2,100 hp steam powered vessel was demonstrated using steam turbines. The mean peripheral velocity of blade is 400 ms and the blades are symmetrical. One of the most popular example of impulse turbine is pelton wheel. This is why we call this type of turbine as impulse turbines. In fact, a series of velocitycompounded impulse stages is called a pressurevelocity compounded turbine. Each set of rings of moving blades is separated by a single ring of fixed nozzles. 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. 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. Energy from water will be changed to mechanical energy. Steam turbines their construction, selection and operation pdf. For a steam turbine, steam is the driving source of the energy.
Design charts for impulse turbine wave energy extraction. In fact, a series of velocitycompounded impulse stages is called a pressurevelocity. 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. Several physical principles are employed by turbines to collect this energy. The inlet angle to the turbine is given and velocity coefficient is given. The steam turbine working principle and theory has been explained in. 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 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. Chap er 6chapter 6c p 6ha er steam tt t m m urbinebneurbineb ne steam turbine is one of the most important prime mover for generating electricity. In impulse turbines, the total head available is first converted into the kinetic energy. Simple impulse turbine that if the expansion of steam from the boiler pressure to condenser pressure takes place in. It is composed of three zones of blades, where the first and. Turbine is a prime mover to subtract energy from fluid. The decrease in the absolute velocity of the fluid across the two rotor blade rows r 1 and r 2 is due to the energy transfer. As a velocity compounded stage uses approximately the same heat drop as four impulse stages, it is used to provide a shorter and cheaper turbine, although with some sacrifice in efficiency. The moving blades are connected to turbine shaft while the fixed blades are joined to the casing. The absolute velocity is then reduced in the rotor, but the static pressure and the relative velocity remain constant. Thermal engineering ii imp qusts teii important questions. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors. Any further reduction in pressure will not produce any further increases in the velocity.
In the impulse reaction turbine the fixed and moving blades are of similar form consisting of converging passages to give a pressure drop in each case. Impulse stages may be either pressurecompounded, velocitycompounded, or pressurevelocity compounded. Turgo turbine, a modified form of the pelton wheel. The pressurevelocity compounding is a combination of the above two types of compounding. By definition, the impulse turbine has a degree of reaction equal to zero. 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. The fluid energy which is reduced on passing through. Its modern manifestation was invented by charles parsons in 1884 the steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results. Other impulse turbines are known as curtis, zoelly and. Velocity diagram of pressure compounded reaction turbine blade configuration the moving blades of a reaction turbine are easily distinguishable from those of an impulse turbine in that they are not symmetrical and, because they act partly as nozzles, have a shape similar to that of the fixed blades, although curved in the opposite direction. In fact, a series of velocity compounded impulse stages is called a pressure velocity compounded turbine.
Before describing compounding, understanding of the steam turbine is necessary. By 1905, when steam turbines were coming into use on fast. It was discovered in 188 0 by an american engineer lestera. Compounding of steam turbine is used to reduce the rotor speed. The theory is given for a singlestage impulse turbine and velocity compounded impulse turbine. Francis turbine, a type of widely used water turbine. A series of velocitycompounded impulse stages is called a pressurevelocity compounded turbine. Impulse turbines change the direction of flow of a high velocity fluid or gas jet. The nozzle angles for the first two impulse turbines are the same.
As a velocitycompounded stage uses approximately the same heat drop as four impulse stages, it is used to provide a shorter and cheaper turbine, although with some sacrifice in efficiency. A gas turbine uses the hot gases of combustion directly to produce the mechanical power. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. Consists of two stage of nozzles followed by two rows of moving blades. It provides a very detailed learning using graphics and animation in explaining a turbine classification of the different impulse and impulse reaction types.
Pelton turbine among different types of impulse turbines, pelton wheel is the only turbine beingused at present. The cost of turbine is less because less number of stages. Fig5subik kumarschematic diagram of pressurevelocity compounded impulse turbine. Velocity compounded impulse turbine contd velocity compounded. Turbine casing is very simple and need not be very.
Velocity compounding curtis impulse turbine 23 pressure compounding. There are two classical types of turbine stage designs. In the impulsereaction turbine the fixed and moving blades are of similar form consisting of converging passages to give a pressure drop in each case. As the outlet pressure decreases, the velocity increases. A working fluid contains potential energy pressure head and kinetic energy velocity head. A pelton turbine develops 2000 kw under a head of 100 m and with an overall efficiency of 85%. 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. What is the velocity and pressure compounding in a turbine. The impulse generated in this procedure is used to provide the momentum to the blades. Pressure compounding or rateau stage in a pressure compounded. Steam turbine types the cbt also covers steam turbine governing system in detail and includes woodward type governor operation governor working. The various turbine types have been explained in detail.
In the case of 50% reaction parsons turbine the enthalpy drop is the same for both fixed and. Velocity compounding, pressure compounding and pressure velocity compounding. The method in which energy from steam is extracted in more than single stage is called compounding. In the turbine, the energy level of the working fluid goes on decreasing along the flow stream. Eventually, a point is reached called the critical pressure ratio, where the velocity is equal to the velocity of sound in steam. There is less of a drop in pressure and consequently a smaller increase in velocity. Note that the velocity diagram of the turbine differs from that of the compressor, in that the change in tangential. Impulse turbine efficiency calculation methods with organic. Presentation about steam turbines including how is it work, parts, operations and controlling with examples of the turbine exists in our plant eppc. What are the advantages and disadvantages of velocity compounded impulse turbine.
The impulse wheel carries two or three rows of moving blades. Fundamentals of fluid mechanics chapter 12 pumps and turbines. As only a portion of the velocity available is developed in each set of nozzles, the blade velocity is kept down to a reasonable amount. A method for selecting impulse turbine wave energy to operate at a specified wave site power has been described. In steam turbine compounding there are three major forms. It has the advantage of reduced blade velocities, reduced steam velocities and equal. 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. Nozzle angle, erosive wear, efficiency loss, turgo turbine, jet velocity. Steam turbine and steam nozzle interview question and answers. Fig4subik kumarvelocity diagram of pressure compounded impulse turbine. Steam issues from the nozzles of a delaval turbine with a velocity of 1200 ms. If high velocity of steam is allowed to flow through one row of moving blades, it produces a rotor speed of. By 1905, when steam turbines were coming into use on fast ships such as hms dreadnought 1906 and in landbased power applications, it had been determined that it was desirable to use one or more curtis wheels at the beginning of a multistage. Compounding of steam turbines is the strategy in which energy from the steam is extracted in a.
Pressure compounding, velocity compounding, pressurevelocity. In the impulse turbine, the gases will be expanded in the nozzle and passed over to the moving blades. In the reaction turbine, the rotor blades themselves are arranged to form convergent nozzles. Oscillating water column wave energy convertor is widely used in the world. Various methods of loss calculation were explored in the search for a method sufficiently accurate to. A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. It operates under v ery high heads upto 1800 m and requires comparatively lesser quantity of water. The project was based on an existing impulse turbine, a onestage turbine set in an organic rankine cycle with the working fluid being r245fa.
And as such its pressure remains constant while passing over the blades. Since the turbine is of the impulse type, the pressure of the fluid remains. In this type, the total pressure drop expansion of the steam take place only in the first nozzle ring. The steam after expanding through nozzles enters the first ring of moving blades at a. The inlet velocity triangle the outlet velocity triangle at the inlet there is no component of absolute velocity in the direction of rotation. What was the name of this famous vessel and who is credited for this invention.
Turbines are subdivided into impulse and reaction machines. This falls under the category of power producing turbomachines. Kaplan turbine, a variation of the francis turbine. Pressurevelocity compounding combined impulse turbine total pressure drop is divided into two stages the total velocity obtained in each stage is also compounded 26 gas turbines 27 no transcript 28 gas turbines.
The rings of moving blades are separated by rings of fixed blades. 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. The moving blades are keyed to turbine shaft and fixed blades are fitted to casing. That is, the blade pushes and turns the fluid in the direction of the blade motion, thereby doing work on the fluid. 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. Impulse turbine efficiency calculation methods with. Difference between impulse turbine and reaction turbine in an impulse design of steam turbine, there is an attempt to attain no expansion of steam within the moving blades.
Velocity compounding an impulse turbine that is velocity compounded has fixed and moving blades. Three main types of compounded impulse turbines are. Each stage consists of rings of fixed and moving blades. The force still comes from rate of change of momentum, but not as obviously as in the impulse turbine. The first two stages are impulse stages and the last two are reaction stages. This divides the velocity drop across the stage into several smaller drops. The blades change the direction of steam flow without changing its pressure. Astern turbines generally consist of a single wheel on which are mounted a tow stage velocity compound followed by a single stage wheel. The steam after expanding through nozzles enters the first ring of moving blades at a high velocity. Pdf power plant lecture notes chapter4 steam turbine. The mass of steam flowing through turbine per hour is 900 kg. A turbine is a device that extracts the energy from a fluid flow and converts it to useful work.
It consists of a nozzle or a set of nozzles and rows of moving blades attached to the rotor or. 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. The velocity compounded impulse turbine has moving and fixed blades. Crossflow turbine, also known as bankimichell turbine, or ossberger turbine. Impulse stages may be either pressure compounded, velocity compounded, or pressure velocity compounded. The moving blades are keyed to the turbine shaft and the fixed blades are fixed to the casing. It covers the governing system and includes working of the woodward governor type. The optimum rotational speed of the turbine was in.
The work ratio of the highesttolowest pressure stages in an ideal turbine is 3. Many turbines combine impulse and reaction, so that it is difficult to separate them conceptually. Velocity compounded impulse turbine velocity drop is arranged in many small drops through many moving rows of blades instead of a single row of moving blades. Impulse blading may have up to 20% reaction effect at mean blade height. A turbine was investigated by various methods of calculating its efficiency. The rotor of an impulse turbine is 60 cm diameter and runs at 9,600. Turbines a turbine is a rotary engine that exerts energy from a fluid flow and converts it into useful work. What is velocity and pressure compounding in impulse turbine. If the steam is to enter the blades without a shock, what will be the blade angles. The fixed blade angles of the two reaction turbines equal to the given inlet angle. The following important points may be noted for impulse turbines. 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. What are the advantages and disadvantages of velocity compounded turbines. There are two basic types of turbines according to the mode of steam.
600 300 1375 77 178 1581 368 1548 653 148 1515 1492 1139 1158 986 186 1651 510 806 1558 1208 1095 122 815 831 97 476 1238 816 1416 1013 382 1333 1647 1220 1211 263 1479 862 934 971 854 532 1034 925 58