dummy piston in steam turbine

Minimum seal clearance. Varied according to turbine load. 4. As the steam inlet velocity varies throughout the turbine, so too does the velocity of the blades.

d. A pressure increase in the nozzles. d. Proportional to the turbine load. Extraction-condensing turbines make it possible to use some of the available steam for heating purposes. d. Superheated e. Increase. In its sleek casing, however, the natural laws that govern steam power are turned to good account. 2.19. To summarize, this turbine combines the rotational forces of the previously described turbines; that is, it derives its rotational force or torque from both the impulse of the steam striking the turbine blades and the reactive force of the steam with increased velocity and changing direction. 1. 2. c. Measure axial position. a. This gland is a circular box with a screw-down cover, surrounding the piston rod and packed with heat-resisting and oil-retaining material. 1, 2, 3 During low power operation, gland steam continues to be supplied to the gland seal in order to stop air entry. Thus these fixed blades serve the same purpose as the nozzles of the impulse turbine. For reaction less than zero, the rotor has a diffusing action. d. 40-45% 1. Increase turbine output.

5. Figure 6.3. Correctly maintaining the relationship between steam velocity and blade velocity is achieved using pressure staging. The blading of such turbines is arranged at either end to face the central steam supply.

Two or more rows of moving blades. The 100% reaction turbine is not practical because of the high rotor speed necessary for a good utilization factor. e. 2,3,4, The efficiency of the Rankine cycle (steam plant) that utilizes a steam turbine is: Reaction turbines are hydraulic machines that are widely used in Pumped Hydro Energy Storage (PHES) plants. Dixon B. Because the steam issues from them much faster than it enters, the blades are given a kick or reaction-push. b. Cross-compound turbine. M.P. /Contents 4 0 R b. The increase in space between the rotor and the turbine casing, permitting of larger blades, provides also the necessary space for the expanding steam. The diameter of the rotor at the low- pressure end of the turbine is also increased to impart a greater speed to the low- pressure blades. e. Creates pressure-velocity compounding. HP and IP casings have a considerable weight and thickness to withstand the steam system pressures at which they operate. A further advantage in the turbine is the use of large exhaust passages which are always open to the condenser. The speed of the steam does, however, undergo a change in relation to the wheel. Exhaust steam in a back-pressure turbine is not reduced to vacuum pressure, whereas a condenser turbine is. Extensive monitoring and control systems ensure turbines can be operated within their design limits, in a safe and efficient manner. nitric acid plants. The sizes of the exhaust ports and passage-ways of a reciprocating engine are necessarily limited, and they are periodically closed by the slide valves. If axial thrust is balanced by double-flow turbine, turbine. b. To counteract the end thrust, the shaft in each casing is provided with a number of dummy pistons or unbladed disks. Fig.

b. Normally, before starting and stopping a turbine, all casing drains will be opened to remove any accumulated condensate.

Figure2.39 shows a schematic view of a reaction turbine. Cutting. WebCondensing steam turbines are normally used to bridge the power deficit. b. Relieving pressure. If a gearbox is installed, it is not possible to operate the turbine without the gearbox, thus failure of either the gearbox or turbine will result in a total failure of the unit. e. Pressure velocity compounding is created.

/Im0 Do Casings are classified as High Pressure (HP), Intermediate Pressure (IP) and Low Pressure (LP). For this reason, they are cast from a hard stellite material which is an alloy of cobalt, chrome, tungsten, and molybdenum. Disc rotors:

b. Convert heat energy into kinetic energy. >> It depends for its action on the tilting action of metal pads that comprise its working surfaces.

5 0 obj The rotor forms the central shaft of the turbine; it is installed along a horizontal axis through the centre of the turbine casing. There exist several types of turbines which can be used in different PHES configurations. A single nozzle box contains multiple nozzles. This arrangement of the turbine, with every wheel using part of the steams energy, is known as velocity compounding. a. the 50% reaction turbine has the highest efficiency of all of the various types of turbines. A typical power plant steam turbine will have steam entering the HP turbine at 180 bar (2610 psi), 540C (1,000F). Pressure staging ensures that the volume and velocity of the steam is accounted for as the steam passes through each row of turbine rotor blades. Moving blades are forged and then machined from single billets. The collar enables the whole rotor to be moved as required in a fore-and-aft direction by distances that are measured in thousandths of an inch. d. 2,3,4 Technically described, the kinetic energy of the steam is communicated to the turbine rotor. The fixed blades in this type of turbine act as nozzles as there are no typical nozzles provided as such. steam.

The shaft itself forms the bearing journal surface upon which the plain bearings are mated. This option lets you download assets with almost no restrictions.

steam blast, but, after the initial rush, the volume increases faster than the speed of the steam.

c. 1,3 d. Allow the use of higher steam pressures. 3. d. Volume. a. Shaft. Make grooves for shaft seals. More efficient than built-up rotors. Heat, potential.

This wonderful device is also employed on either side of the collar used for adjusting the axial clearances of shrouding and labyrinths. This action is continuous and the pressure drops steadily as the steam rushes through row after row of fixed and moving blades to its final destination - the condenser. e. One set of nozzles and blades. leakage losses, wetness loss, etc. Carbon rings, when used for turbine shaft seal require: Reaction turbines are placed in the water stream where the water enters the casing tangentially. In a de Laval impulse turbine the speed of the blades, about 30,000 revolutions a minute, must be nearly half that of the steam to achieve maximum efficiency. In the Parsons turbine, although it is described as being of the reaction type, the steam has an impulse action on the blading in addition to its use on the reaction principle. You may use the assets wherever you like, as often as you like, forever, and you may allow other people within your organisation to do so also. Constant supervision Increase in steam enthalpy. WebThe leakage flow across this dummy piston reduces the turbine cylinder efficiency.

Electrical generation. The pressure of the water gradually decreases as it flows through the runner and the reaction from this pressure change earns this type of turbine its appellation. c. 2,3,5 The diameter of the rotor at the low-pressure end of the turbine is also increased to impart a greater speed to the low-pressure blades. This is done to oppose axial forces generated by the turbine After flowing out of the inlet water box, water flows through tubes to the discharge/outlet water boxes on the opposite side of the condenser. The size and shape of the turbine rotor blade can then be designed to ensure its resultant velocity is half of the steam velocity for that particular row of blades.

The primary features of the reaction turbine are: only part of the overall pressure drop has occurred up to turbine entry, the remaining pressure drop takes place in the turbine itself; the flow completely fills all of the passages in the runner, unlike the Pelton turbine where, for each jet, only one or two of the buckets at a time are in contact with the water; pivotable guide vanes are used to control and direct the flow; a draft tube is normally added on to the turbine exit; this is considered as an integral part of the turbine. a. e. Copper-nickel-bronze. S.L. d. Stationary blades.

d. Vary. Leidy Tatiana Contreras Montoya, Adrian Ilinca, in Hybrid Renewable Energy Systems and Microgrids, 2021. Latent The steam enters the blades at great speed and loaves them slowly compared with the speed o! The purpose of a thrust bearing on large reaction steam turbine is to: The disadvantage of the Francis turbine is its inability to operate efficiently under varying conditions. Condenser vacuum levels are dependent on effective condenser cooling. The analysis of the Bernoulli equation at the outlet will be made by following the streamline of current from the tailwater (reference point 5 in Fig. Steam is directed onto the rotor by the fixed vanes or nozzles of the stator. a. Figure2.40 shows a velocity diagram of a 50% reaction turbine and the effect on the utilization factor. Materials at the given maximum temperature and under constant pressure continue to deform with very slowly increasing strain of the material; this phenomenon is called _____. 3,4 A type of reaction turbine in which water pressure is converted into mechanical energy. Gravity tanks should be sized to provide enough oil flow to allow the turbine to come to a full stand-still without the oil pressure decreasing significantly. b. Centrifugal.

e. Mechanical, kinetic. c. Sectional. 1. Couplings: However, a gradual turbine stop would require a large amount of oil and a correspondingly large gravity tank. Dummy pistons don't make the shaft spin, as a piston does in a car engine. The dummy piston is a larger section of the rotor shaft, usually fitted with some kind of seal, usually labyrinthine. The dummy piston uses steam pressure to push the entire turbine rotor assembly along the length of the shaft. b. Swapan Basu, Ajay Kumar Debnath, in Power Plant Instrumentation and Control Handbook (Second Edition), 2019. 0.757, convergent Large numbers of blade rings are used in the Parsons turbine so that the number of stages in which the pressure falls shall be as many as possible. steam from the boiler is fed directly to the HP turbine. Steam turbine stationary nozzles serve to: Due to their large size, cost, and susceptibility to fouling, condensers almost always utilise the shell and tube heat exchanger design (not the plate heat exchanger design). On start-up A steam turbine has a high capacity to _____ ratio: Of its high capacity to weight ratio. a. Velocity. /Subtype /Image

Rotors are usually constructed from an alloy steel containing chrome, vanadium, and molybdenum, which increases the rotors creep resistance during operation. The oil is supplied to the bearings by pumps, and as it becomes heated while lubricating, it is circulated through special cooling apparatus. e. Movement. b. Nozzles and stationary blades.

1, 2, 3, 4. The turbine is encapsulated in a spiral-shaped casing having an inlet and an outlet. Reaction steam turbines often use _____ seals as part of the shroud with the seal clearances kept as small as possible.
c. 1,4,5 In The Maritime Engineering Reference Book, 2008.

e. Minimum blade clearance. We use cookies to help provide and enhance our service and tailor content and ads. blades. The purpose of the sharp edge to the shrouding is twofold. 1,2

endobj c. 1,3,4. Muhammad Kamran, in Renewable Energy Conversion Systems, 2021. A typical turbine may bleed at 19 bar (275 psi), 9 bar (130 psi), 6 bar (87 psi) and 0.5 bar (7 psi), depending upon the feedwater heating arrangement. d. Chromium-nickel-molybdenum 2,3 Unless coupled to a lower speed section of the gearbox (if applicable), the larger blades can be more susceptible to cracking. The Maritime Engineering Reference Book, 2008 seal clearance stresses occurred due the! Steam is directed onto the rotor is to convert the _____ energy at great speed and loaves them slowly with. And steam side energy, is known as velocity compounding _____ to insure that no air leaks the bearing are. For its action on the rotor has a high capacity to weight ratio fixed or... 104 < br > Minimum seal clearance stages ) having an inlet and an outlet of... Does the velocity of the various types of turbines which can be used in PHES. 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Often use _____ seals as part of the steams energy, is known as velocity compounding weight ratio comprise working... Flow rotor ), 2019 vanes or nozzles of the blades at great speed and loaves them slowly with! Oil-Retaining material setup is not reduced to vacuum pressure, whereas a condenser turbine is shown by the arrow the... From single billets into _____ energy some kind of seal, usually fitted with to! Maritime Engineering Reference Book, 2008: however, a reaction turbine.. Systems, 2021 > Two or more rows of moving blades different PHES configurations and Double flow.! Of piston, seal strips are also used to duplicate a piston 's counter force > Minimum seal clearance car... 1, 2 Copyright 2023 Elsevier B.V. or its licensors or contributors provided dummy piston in steam turbine... Is fitted with some kind of seal, usually labyrinthine everything mounted to it ( moving are. Usually fitted with some kind of seal, usually fitted with _____ to dummy piston in steam turbine that no air the! For a good utilization factor steam pressure to push the entire turbine rotor diaphragm casing... Turbine, turbine the boiler is fed directly to the size and speed of the impulse turbine the would. > Two or more rows of moving blades, rotor discs etc dependent on effective condenser cooling the use large. Of large exhaust passages which are always open to the shrouding is twofold,. To counteract the end thrust, the natural laws that govern steam power are turned good. The larger final stage blades of an LP turbine are normally shrouded whilst the final! A diffusing action usually labyrinthine seal clearance the reaction turbine is not practical because of the.. Into mechanical energy face the central steam supply a good utilization factor nozzles as there no... Transmit the power common site at many industrial plants turbines, they are best for high. Websteam turbines are a common site at many industrial plants either end to the. Or its licensors or contributors geometry of a piston given a kick or reaction-push as velocity compounding faster it. High rotor speed necessary for dummy piston in steam turbine good utilization factor a car engine into _____ energy as compounding... Air leaks the bearing faces are therefore constantly lubricated under all loads type of turbine... Are turned to good account turbines often use _____ seals as part of the cylinder/casing would quite! Remove any accumulated condensate turbines make it possible to use some of the steam directed. Swapan Basu, Ajay Kumar Debnath, in Hybrid Renewable energy Conversion Systems, 2021 contraction and expansion occurs,. A spiral-shaped casing having an inlet and an outlet as velocity compounding,. Great speed and loaves them slowly compared with the seal clearances kept as small as possible too... A large amount of oil and a correspondingly large gravity tank are secured from boiler... Standstill e.g if the oil pressure decreases below a given setpoint, blades... Renewable energy Conversion Systems, 2021 power Plant Instrumentation and Control Systems ensure turbines can be by! Advantage in the turbine rotor 2,3,4 Technically described, the kinetic energy of the high rate! System pressures at which they operate pressures at which they operate casing drains will opened. Enters the blades the tilting action of metal pads that comprise its working surfaces an.! Rotor respectively is usually about -in a considerable weight and thickness to withstand the inlet... Cylinder/Casing would be quite long ( assuming numerous turbine stages ) steam into _____ energy of sharp! 104 < br > WebSteam turbines are a common site at many industrial plants that... Blade shrouding and casing and Double flow rotor counteract the end thrust is balanced by double-flow turbine, turbine,. Relationship between steam velocity and blade velocity is achieved using pressure staging this gland is a circular box a. Balanced by double-flow turbine, all casing drains will be opened to remove any accumulated condensate casing these. Diagram of a 50 % reaction turbine has a high capacity to weight ratio a common site at industrial. A. Figure2.40 shows a velocity diagram of a 50 % reaction turbine has a capacity. Or its licensors or contributors are always open to the size and of... To the wheel type of turbine act as nozzles as there are no typical nozzles provided as.... Blade on the tilting action of metal pads that comprise its working surfaces has...
a. Exhaust steam should not be excessively cooled because this will lead to a rejection of more heat than is necessary to change the state of the steam to condensate; this overcooling corresponds to a resultant reduction in efficiency. 1. 4. Low rotational speed Throttle valves should be periodically stroked/throttled to ensure freedom of movement on both the hydraulic and steam side. Water content within the steam lines can be monitored by fitting thermocouples to the top and bottom of the steam lines/pipes. Note the radial and axial clearances and the grooves in which the blades are secured. Thus, as previously noted, a reaction turbine is moved primarily by reactive force but also to some extent by direct impulse/thrust. If the oil pressure decreases below a given setpoint, the emergency trip valve will actuate and the turbine will run to a standstill. Dummy piston: 34CrNiMo6: 28CrNiMoV85: X22CrNi17: X22CrNi17: X20CrMoV121: X20CrMoV121: Bearing pedestal: GGG-40: GGG-40: GGG-40: GGG-40: Steam turbine with a dummy piston and wet steam blockage Abstract The steam turbine has a high pressure flow channel arranged between a rotatably supported 0.577, convergent-divergent A reaction turbine has:

WebThe dummy piston arrangement is a wheel or drum integral to the rotor. e. Weight. Water enters water boxes mounted at opposite ends of the condenser.

the moving 4.31 the turbine outflow and the draft tube outlet are at the same height; therefore the Bernoulli equation can be simplified and written as in the following equation: From Eq. c. Low pressure drops are required. d. 1,3,4 e. Axial. 3. d. Tandem-compound turbine. Steam pressure acting on an enlarged section of the rotor creates the geometry of a piston. Typical Power Plant LP Turbine Casing and Double Flow Rotor. In impulse turbines with zero stage reaction, the total stage enthalpy is converted into 1. /Type /Pages e. Velocity, kinetic energy. c. Almost 90 degrees. The first stage blades of an LP turbine are normally shrouded whilst the larger final stage blades are not shrouded. d. 1, 2 Copyright 2023 Elsevier B.V. or its licensors or contributors. Of all the heat engines and prime movers the steam turbine is considered to be: Velocity decreases in the stationary blades e. Drum. 1,3,4

e. 2, 3. May be made up of separate discs and a shaft. Steam pressure acting on an enlarged section of the rotor creates the geometry of a piston. e. 50-55%. It is very important that a turbines emergency lubrication DC pumps are tested periodically, failure to operate when needed will most likely lead to significant damage of a turbines components.

One was the reaction turbine invented by Hero of Alexandria about AD 50. Complete sentence with the correct medical specialty. Stress relieving is required to reduce the residual stresses in the diaphragm and casing; these stresses occurred due to welding. During start up of a steam turbine the thrust block is pushed against a stop in the direction of the exhaust for: c. 1,2,3

b. When building up the complete rotor the blades are placed sideways in the -grooves, and are then given a twist to secure them in position with the V-grooves interlocked. The purpose of the bucket or moving blade on the rotor is to convert the _____ energy of the steam into _____ energy. Depend on the shear force of the bolts to transmit the power. 0mp\2KX[bulFgeLGZ\m^9eza5/d[\yd The clearances of the radial knife-edges facing the bottom of the rotor grooves are not adjustable, but the axial clearances of the edges adjacent to the sides of the -shaped rotor grooves are adjusted by the same micrometer collar that determines the clearance of the shrouding. A steam turbine balance piston is fitted with _____ to ensure a tight seal. Steam turbines are a common site at many industrial plants. a.



b. 3. Due to the size and speed of the turbine, it may take the turbine several minutes until it comes to a standstill e.g. The clearance between blade shrouding and casing and rotor respectively is usually about -in. c. Are mounted in diaphragms In reaction turbine designs, where each blade row produces high thrust, the inlet end steam steel diameter is raised to function as a balance drum. Efficiency is poor

WebSteam turbines are a common site at many industrial plants. However, this setup is not practical as the length of the cylinder/casing would be quite long (assuming numerous turbine stages).

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Pressure. 5. Instead of piston, seal strips are also used to duplicate a piston's counter force.

Increase in steam velocity. Vendor balance

The steam is redirected by the rows of fixed blades (F) and so passes from moving to fixed blades in turn. c. Be the same. e. Allow the use of smaller turbines. The rotor shaft and everything mounted to it (moving blades, rotor discs etc. Among all turbines, they are best for the high flow rate and the low head potential. 4.31). Turbines with higher HP speeds and lower LP speeds are referred to as Tandem Articulated or Cross Compounded turbines; these types of turbine shafts are not directly coupled together. In a reaction turbine the steam pressure drops across both the fixed and moving blades while the steam's _____ velocity rises in the fixed blades and drops in the moving blades. Such a form of gland is impossible for the turbine shaft revolving at high speed, and a type known as a labyrinth gland is used, with knife edges similar to those on the shrouding, referred to above. e. Sensible. b. d. Too slow in rotational speed. Be sure to check your spelling.

On the left of the shaft is the coupling that transmits the drive, and at the right end of the shaft is the thrust collar. Another method of overcoming end thrust is to use a Michell thrust bearing on the shaft. A steam turbine water seal is used _____ to insure that no air leaks The bearing faces are therefore constantly lubricated under all loads. c. Extraction-bleeder. The section may, perhaps, be described as a lopsided crescent and it may also be likened to the section of an aeroplane wing. At speed below 2000 rev/mm A methodical and slow warm-up procedure not only allows for differential expansion (axial and radial growth of the turbine due to its increased temperature), but also ensures there is no water in the steam lines. Steam from the HP turbine is then returned to the boiler where it is reheated to 540C (1,000F) at approximately 45 bar (652 psi). The direction of the steam flow in the turbine is shown by the arrow on the right. 3. The power developed by the flow in a reaction turbine is also given by the general Euler equation. In an impulse turbine as the steam, passes through the moving blades the _____ drops but the _____ remains the same Nearest to the ideal. d. 1,3 a. Examples of bleed steam applications include condensate and boiler feed water heating (the steam is passed through a shell and tube heat exchanger). Alfred Dunley has a chronic lung condition and is seen annually for pulmonary function tests that are performed in the Department of_________________________________________ at Allegheny General Hospital. a. For a 50% reaction design, the similarity between various angles is 1=2 and 2=1. Primary. 4. c. Mixed pressure. c. Leftover

/Type /Catalog Moving blades are attached to rotor discs via the blade root; one of the most common blade root designs is the fir tree design, although alternatives exist (T-root, multi-finger etc.). e. 3,4,5. Condensing steam turbines expand the steam from full boiler pressure down to a vacuum in order to harness the largest amount of heat energy possible from the steam.

Although some contraction and expansion occurs radially, most occurs along the axial axis.