The pressurevelocity compounding is a combination of the above two types of compounding. The force is depends on the time interval and velocity of jet strikes the blades. Each stage comprises its ring of nozzle and 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. In a velocity compounded impulse turbine when steam flows. The reaction principle, the impulse turbine, compounding of impulse turbine. In the case of the reaction turbine, it is not necessary to make special blade arrangements to reduce rotor speed. 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. The exit steam from one turbine is made to enter the nozzle of the succeeding turbine. In fact, a series of velocitycompounded impulse stages is called a pressurevelocity compounded turbine. This highvelocity strikes the turbines rotor and the speed of the rotor.
To improve the thermal efficiency of any power plant, generally high pressure near about 120 to 140 bar, high temperature and highvelocity steam is used. Impulse turbine and reaction turbine nuclear power. Curtis to solve the problems of a singlestage impulse turbine for use with high pressure and temperature steam. The rings of moving blades are separated by rings of fixed blades. When the steam passes through the moving blades the velocity drops but the pressure remains the same.
In an impulse turbine, the degree of reaction is zero. Compounding is done to reduce the rotational speed of the impulse turbine to practical limits. This results in lower or more acceptable steam flow speeds and a better turbine efficiency. Impulse turbine and reaction turbineprinciple, working.
Velocity compounding of the impulse turbine 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. The compounding is the way of reducing the wheel or rotor speed of the turbine to optimum value. Pressure energy of steam at turbine input gradually extracted in multiple steps. This condition will exist if the blade velocity is equal to one half of the steam velocity. Pressurevelocity compounding curtis turbine curtis turbine pressurevelocity compounding. Difference between impulse and reaction turbine with pdf. 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. There are two basic types of turbines according to the mode of steam. Velocity compounding, pressure compounding and pressure velocity. We decided to use the pressure compounding method for the impulse stages of the turbine.
Compounding of turbines compounding of 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. In this type, the total pressure drop expansion of the steam take place only in the first nozzle ring. Steam turbine working principles based on working principle the.
Impulse turbine efficiency calculation methods with organic rankine cycle johan e. There are a number of rows of moving blades attached to the rotor and an equal number of fixed blades attached to the casing. The impulse turbine changes the velocity of the water jet. This turbine is connected to a generator which generates electricity. This divides the velocity drop across the stage into several smaller drops.
Water turbines are classified into 2 typesimpulse type. This is why we call this type of turbine as impulse turbines. The turbine is located at the end of penstock from where the pressurized water strike the blades of turbine at high velocity making it to rotate. Figure show the arrangement of a velocity compound turbine.
In fact, a series of velocitycompounded impulse stages is called a pressurevelocity. Difference between the impulse and reaction turbine. Comparison between velocity compounding and pressure compounding. Velocity kinetic energy of steam is converted to useful work in more than one stage. Impulse and reaction principles, compounding, velocity diagrams for simple and multistage turbines, speed regulationsgovernors and nozzle governors. Cross compound steam turbine arrangement for marine use. Velocity compounded impulse turbine contd velocity compounded impulse turbine from me 430 at the city college of new york, cuny. Impulse turbine works on the basic principle of impulse. Thermal engineering pdf of rk rajput for mechanical. What is pressurevelocity compounding curtis turbine.
This turbine used to rotate the generator, which produces electric power. The pressure velocity compounding is a combination of the above two types of compounding. Pressure compounding or rateau stage in a pressure. Turbines a turbine is a rotary engine that exerts energy from a fluid flow and converts it into useful work. Pi inlet pressure, pe exit pressure, vi inlet velocity, veexit velocity. Each of the simple impulse turbines would then be termed a stage of the turbine. Dahlqvist approved 20121016 examiner damian vogt supervisor jens fridh commissioner contact person 1 abstract a turbine was investigated by various methods of calculating its efficiency. Our blade velocity ratios for each stage had to have the same ratio as the diameter of each stage. In a velocity compounded impulse turbine, when steam flows through the second row of moving blades, a velocity increases b velocity decreases c velocity remains constant d pressure remains constant. There is less of a drop in pressure and consequently a smaller increase in velocity. Steam turbine working principle of impulse and reaction. On this channel you can get education and knowledge for general issues and topics.
The force due to change of momentum causes the rotation of the turbine shaft. How to solve numericals on impulse turbine part 1 duration. Pdf steam turbine find, read and cite all the research you need on researchgate. Pdf power plant lecture notes chapter4 steam turbine. Pressure compounding of an impulse turbine is the use of a number of stages of nozzle and blade to reduce progressively the steam pressure. In order for the steam to give up all its kinetic energy to the moving blades in an impulse turbine, it should leave the blades at zero absolute velocity. Construction of velocity compounding turbine with diagram. Three methods of compounding in steam turbines blogger. In order to reduce the rotor speed up to about 400 msec, compounding of steam turbine is necessary.
The above figure shows the velocity and pressure curve while working fluid passing through the blades of velocity compounded turbine. 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. Cross compound steam turbine arrangement compounding is the splitting up, into two or more stages, of the steam pressure or velocity change through a turbine. Impulse stages may be either pressurecompounded, velocity compounded, or pressure velocity compounded. The steam from the boiler passes through the first nozzle ring where its pressure drops and velocity increases. In fact, a series of velocity compounded impulse stages is called a pressure velocity compounded turbine. Unit iii unit iii steam nozzles and turbines flow of steam through nozzles, shapes of nozzles, effect of friction, critical pressure ratio,supersaturated flow. Compounding free download as powerpoint presentation. The blades change the direction of steam flow without changing its pressure. The methods of reducing rotor speeds, namely, pressure compounding, velocity compounding, and pressurevelocity compounding have all applied to impulse turbines. Steam expands from boiler pressure to the condenser in one stage. Here the kinetic energy velocity is extracted from working in multiple stages. Velocity compounded impulse turbine contd velocity. Therefore, the turbine rotor will run at a high speed about 30,000 rpm which is not useful for practical purpose.
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. 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. The impulse generated in this procedure is used to provide the momentum to the blades. One of the most popular example of impulse turbine is pelton wheel. 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. So, steams pressure drop and it will increase its velocity. Water exiting turbine will have significant velocity want to recover velocity head before exiting downstream to minimize losses draft tube slows water gradually draft tubes for nepalese francis turbine draft tube installation.
Compounding is the splitting up, into two or more stages, of the steam pressure or velocity change through a turbine. Impulsereaction turbine this utilizes the principle of impulse and reaction. What are the types of compounding in steam turbines. Impulse turbine efficiency calculation methods with. 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 method in which energy from steam is extracted in more than single stage is called compounding. Pressurevelocity compounded impulse turbine this is a combination of pressurevelocity compounding. Pressure velocity compounding curtis turbine curtis turbine pressure velocity compounding. The fact that the pressure does not drop across the moving blades is the distinguishing feature of the impulse. Compounding is achieved by using more than one set of nozzles, blades, rotors, in a series, keyed to a common shaft. Therefore, for good efficiency the blade velocity should be about one.
The nozzle angles for the first two impulse turbines are the. At the bottom of every article the pdf link is attached make sure if you want you can easily download. The degree of reaction of a turbine stage stator nozzles plus rotor blades is the fraction of the fluid static enthalpy drop which occurs in the rotor see section 2. In the impulse turbine pressure drops and the velocity increases as the steam passes through the nozzles. Impulse stages may be either pressurecompounded, velocitycompounded, or pressurevelocity compounded. Difference between the impulse and reaction turbine today we discuss about the main difference between the impulse and reaction turbine, how differentiate both type of turbine according to steam flow, pressure computing, according to size and efficiency. The jet impinges on the turbine curved blade which changes the direction of the flow. What is velocity and pressure compounding in impulse turbine. In a reaction turbine compounding can be achieved only by pressure compounding. It is the most renowned example of impulse turbine. The velocitycompounded impulse turbine was first proposed by c.
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