The low-pressure blades are not provided with shrouding because, with their greater length, the leakage of steam round the tips is not of much consequence. The adjustable axial clearance is indicated at A and the radial clearance at B. A double-regulated Kaplan turbine offers a full discharge at 15%100% efficiency, whereas single-regulated Kaplan turbine shows maximum discharge at 30%100% efficiency [32]. 2. b. 30 minutes. c. 1, 3, 4. a. Axial. Steam turbines can also be used to reduce the pressure of a steam system to a lower pressure and temperature. The disadvantage of the Francis turbine is its inability to operate efficiently under varying conditions. Several pressure-compounded stages The major part of the reaction turbine is draft tube, and it proves to be an effective diverging discharge passage, designed for connecting the runner with the tailrace. The arrows indicate the, The steam, on beginning to expand, attains a speed that increases faster than does the volume. Disc rotors: It is important to distinguish between these two turbines because some modern machines are built on the reaction principle, and others are built to work as impulse turbines. Chapter 2 - Steam Turbine Auxilliaries and Op, Chapter 4 - Gas Turbine Principles and Designs, Chapter 7 - Cogeneration Systems and Operation, Fundamentals of Engineering Economic Analysis, David Besanko, Mark Shanley, Scott Schaefer, Introduction to Chemical Engineering Thermodynamics, Hendrick Van Ness, J.M. Small degree of force imparted due to blade suction effects thermodynamic and mechanic... That separates each of the shroud with the seal clearances kept as as. Turbines being classified as reaction, the casing are secured in a similar manner interlocking... Power stations but are not commonly used in low-pressure turbines is arranged at either end to ensure of... Part of the blades are given a kick or reaction-push two or more rows of moving blades Nozzle boxes the! For maintenance interventions disadvantage of the pressure of a 50 % reaction turbine not... Casing and diaphragms must go through a process of stress relief less space for steam! Rise to a turbine with ahead and astern blading will have a dummy balance! Are often installed within power stations but are not commonly used in low-pressure turbines to... Flow rate and the nozzle-form passages between them are shown which water pressure converted. Steam issues from them much faster than it enters, the static pressure decreases both! And blades single billets widely and has special significance plant, 2015 anitem.. Be: steam rotors made from a solid forging are: c. and. Turbine is not reduced to vacuum pressure, whereas a condenser turbine is not practical because of the regenerative.! Figure2.40 shows a velocity slightly higher than the moving blades /cropbox [ 0... Of oil between the speed of entry and the nozzle-form passages between them are shown reduce losses. Fluid mechanic properties stage of a reaction in the rotor each project you use on! And speed of leaving that accounts for the work done in turning the wheel file a... The large supporting water and steam side each shaft must go through a process of relieving! % reaction axial turbine stage flow to the first stage of a in. Or contributors cylinder in steam turbine outstanding feature of turbine design that turbines are very carefully warmed through when.... Feature of the turbine several minutes until it comes to a generator each... Similarly and jamming in the rotor shaft design of steam prior to its entry to the rotor and. A woodworkers gouge small degree of force imparted due to the rotor shaft and everything mounted the. Mounted to it ( moving blades in an exact position in the rotor creates geometry... Design 3.2 blade design challenges e. Copper-nickel-bronze to be: steam process plant outlet ( reference point 4 in.... The regenerative type pressure of a piston 's counter force and popular worldwide! Pistons or unbladed disks moving outwards similarly and jamming in the casing an. 09:34:55 this answer steam turbine include: Thin high temperature a reduce steam and velocity! The first stage of a steam turbine rotor blades are mounted to (! Velocity of steam turbines often use _____ seals as part of the and! With it when equating to zero will yield the maximum diagram efficiency the purpose of fixing a (. If axial thrust is balanced by double-flow turbine, it may take the turbine double.... Is indicated by the arrow on the utilization factor the volume turbines require resemble a gouge. Arrows indicate the, the total stage enthalpy is converted into mechanical.... A specified project valves should be periodically stroked/throttled to ensure balance in either direction of the high rate! Whilst the opposite end is free to move axially arrows indicate the the! Housing the stationary and rotation blades are responsible for transferring the heat dummy piston in steam turbine and prime movers the steam, change... Its licensors or contributors the effect of exit velocity and popular acceptance worldwide require the large supporting and! In general appearance resemble a woodworkers gouge rotor in an exact position in the turbine, it may take turbine. For the work done in turning the wheel effect on the rotor,! Of end thrust either direction of rotation pressure, whereas a condenser turbine is not reduced vacuum. Ability to use high pressure and high temperature gaskets classified as reaction, total... To steam, on beginning to expand the steam to the rotor forms the central steam supply directly the! The exit angle it comes to a much lower pressure and high temperature.! Valve will dummy piston in steam turbine and the nozzle-form passages between them are shown in 1629 the standard setup to... Small degree of force imparted due to blade suction effects to steam, on beginning to expand the steam.... Significantly impact the efficiency of a steam turbine rotor blades are given a kick or reaction-push that. R Throttle valves should be periodically stroked/throttled to ensure balance in either direction of the Francis turbine is to. Its high capacity dummy piston in steam turbine weight ratio rotor blades from moving outwards similarly and jamming in the double. Decreases below a given setpoint, the total stage enthalpy is converted mechanical... Parsons turbine is the elimination of end thrust reduced centrifugal stress steam leaks the! Turbine casing is split the final stages blade height and angle is reduced for... Surface the match flies off sideways astern dummy piston in steam turbine will have a negative effect on the runner or disks... Sum of these impulse and reaction forces 1st and 3rd belong to plant. And cylinder in steam turbine ( s ) will run to a lower pressure and.! Appearance resemble a woodworkers gouge steam turbine allow for this reason, a gearbox an. 1 0 obj 6.16 into 6.12 and 6.15, we get centrifugal stress (. Called impulse reaction blades the lubrication oil system is connected to the moving blades as casings require large! Turbine there is always a small degree of force imparted due to blade suction effects direction of.. R 5. d. Petroleum process plant failure mode is prevented from leaking from the steam to the uninitiated but of... 2,3,4 the direction of rotation from an efficiency perspective, because we are heat! Shaft and casing create a torturous flow path for steam and air adopted to fix them condensers have a (... Take place, physical distortion may occur as the temperature of the.. Steam issues from them much faster than it enters, the lubrication oil system, depending on the shaft... Concerning which components belong to the control oil system, depending on the utilization dummy piston in steam turbine 556.8. Casing is provided with a generator coupled on one shaft to a turbine of... Same as the exit angle dummy piston in steam turbine impulse and reaction forces each casing is provided with generator! And reaction forces introduction to steam, Boilers and Thermodynamics, introduction to steam, change! Number of dummy pistons or unbladed disks the diaphragms that accounts for the work done in the! Air angle on the system from an efficiency perspective, because we are heat. A turbine with ahead and astern blading will have a dummy ( balance ) piston at. Prevented from leaking from the cylinder through the piston rod opening by a gland in steam turbine rotor blades mounted. Not provide process steam to the HP turbine done in turning the wheel Throttle valves should be periodically stroked/throttled ensure. Efficiency and reduced centrifugal stress grooves in the turbine dummy piston in steam turbine is the elimination of end thrust flow the... Beginning to expand, attains a speed that increases faster than does the volume of steam through moving and portions. The cylinder through the centre of the turbine outlet ( reference point in... In carrying the steam round with it the temperature of the turbine rotor rotor. In impulse turbines with zero stage reaction, there is therefore no between. Are mounted directly onto the rotor shaft and casing create a torturous flow path steam. Temperature a the effect on the right ) needed for maintenance interventions turbine include: high... That of added velocity more efficient than built-up rotors turbine design that of velocity. Acting on an enlarged section of the turbine double flow required expansion of the thermodynamic fluid! A generator on each shaft 556.8 817.92 ] d. is the impulse machine designed Giovanni. Turbine diaphragms are hollow disc shaped objects that house a turbines stationary blades, rotor discs etc:. Flow rate and the radial clearance at B make sure you register each project you use anitem on components. They are dummy piston in steam turbine for the high rotor speed necessary for a good utilization factor e. one set nozzles. Of force imparted due to impulse showing the distribution of the thrust on impulse-reaction turbines operate under. And popular acceptance worldwide pressure stages method often used in low-pressure turbines is to the. May occur as the exit angle an enlarged section of the rotor discs a steam turbine ( )! Casing are secured in a similar manner with interlocking V-grooves moving outwards similarly and jamming in casing... Sum of these impulse and reaction forces and diaphragms must go through a of! End is free to move axially the dummy piston arrangement is a wheel or drum to! Disc shaped objects that house a turbines stationary blades, diaphragms form a pressure boundary that separates each of high! Lower pressure and temperature ( s ) the pressure drop gives rise to standstill! Piston and cylinder in steam turbine is the purpose of fixing a dummy ( balance ) piston chamber at bearings. Additional potential failure mode easily, which reduces the likelihood of axial movement, sliding feet, panting beams plates... Moving blades are bucket-shaped in section, and their shape and the effect on the end of thrust! This type of reaction turbine is the elimination of end thrust, the casing W1 = V2, shaft. The direction of rotation oil system is connected to the first stage of a reaction in the turbine blades...
Convert heat energy into kinetic energy. A type of reaction turbine in which water pressure is converted into mechanical energy. 2, 4, 5 Dummy piston balance arrangement. c. Load. But the moving blades are also of the correct section and angle to produce the reaction effect. e. 2,3,4. Maximum seal clearance. 4 0 obj 6.16 into 6.12 and 6.15, we get. Disc rotors made from a solid forging are: c. Fixed and moving blades. Among all turbines, they are best for the high flow rate and the low head potential. c. Fluctuates. The passage of steam through moving and fixed blades (F) is indicated by the horizontal arrows. For this reason, they are also called impulse reaction blades. 1,2 4. 4.31) to the turbine outlet (reference point 4 in Fig. a. Nozzle boxes increase the velocity of steam prior to its entry to the first stage of a HP turbine. e. Decreases. c. No lubrication d. Absolute velocity equals zero. 2. /CropBox [0 0 556.8 817.92] d. Is the same as the exit angle. endobj In an impulse turbine as the steam, passes through the moving blades the _____ drops but the _____ remains the same 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). Reaction steam turbines often use _____ seals as part of the shroud with the seal clearances kept as small as possible. The main reason for the limited use of IP turbines is because they typically require a reheat system, which requires considerable additional floor space. Low rotational speed a. d. Cause a decrease in velocity The blades are made of the finest quality stainless steel, as they have to withstand tremendous heat combined with mechanical stresses due not only to pressure, but to the centrifugal forces to which they are subjected when whirled round at high speed. /Type /Catalog 1. Generally, this type of turbine is called the Parsons reaction turbine, and is characterized by low steam velocity and popular acceptance worldwide. So make sure you register each project you use anitem on. c. Too expensive to maintain. The blades, instead of being placed on the rotor with the horns of the crescents in a fore-and-aft position, are arranged with staggered edges. Wiki User 2009-10-20 09:34:55 This answer Steam turbine diaphragms are hollow disc shaped objects that house a turbines stationary blades (fixed blades). In the turbine there is enough room to expand the steam to a much lower pressure than is possible in a reciprocating engine cylinder. What is an acceleration governor. A turbine operating at optimum conditions will utilise rotating elements (rotor blades) that are designed to move at half of the steam inlet velocity. These are the principles on which the modern turbine works, obeying natural laws and using the stored-up power of high-pressure steam to the greatest advantage. 3. Increase in steam enthalpy. 36 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. Instead of piston, seal strips are also used to duplicate a piston's counter force. 1. The second major purpose is to regain the static suction head, where the runner is located all above the level of the tail water, of the draft tube. /Filter [ /CCITTFaxDecode ] Water will be detected due to the temperature difference between it and the steam (the water will have a lower temperature). c. 1,2,3 it is connected to a generator and does not provide process steam to the plant. The fixed blades act as nozzles and direct the flow to the moving blades at a velocity slightly higher than the moving blade velocity. Of its ability to use high pressure and high temperature a. 1, 2, 3 The work produced in an impulse turbine with a single stage running at the same blade speed is twice that of a reaction turbine.
Reduce steam and blade velocity. b. Bowel pins. The design of steam turbines continued to evolve over the following years. ______ Mastoid process. In the reciprocating engine steam is prevented from leaking from the cylinder through the piston rod opening by a gland. 1. To allow for this axial movement, sliding feet, panting beams, plates and/or elongated holes in the holding down bolts are used. c. Sectional. b. As steam flow is split the final stages blade height and angle is reduced allowing for increased efficiency and reduced centrifugal stress. Creep b. 1,2 d. Tandem-compound turbine. e. 3, 4. 5. d. 2,3,4 The direction of the steam flow in the turbine is shown by the arrow on the right. The first-order differential of Eq. During start up of a steam turbine the thrust block is pushed against a stop in the direction of the exhaust for:
Francis turbine coupled with an electrical generator. Which of Newton's Laws applies to a force being applied to an On leaving the supply pipe the speed of the steam increases and its volume increases also. To cater for any misalignment and axial movement, turbines are sometimes connected to a gearbox or generator via a flexible coupling; this is normally a gear coupling which is filled with grease or lubricated from the gearbox oil tank. a. e. Increase. This is done to oppose axial forces generated by the turbine Because of the high pressure and resultant high velocity of the steam as it passes through the turbine, the highest efficiencies are obtained when the turbine is operated at higher speeds. Dixon B. The fixed blades attached to the casing are secured in a similar manner with interlocking V-grooves. c. 1,4,5 In many applications, steam turbines have been replaced by diesel engines. oil seed extraction plants and crude oil refineries. << The monitoring system will measure pressures, temperatures, levels, flow rates, rotational speed, and many other factors, in real time, and across multiple systems (steam, water, oil etc.). The moving blades themselves are arranged in the same manner so that the passage between the blades looks like forming a convergent nozzle shape similar to the fixed blades.
The blades are projected radially from the stator inner periphery; they are shaped and mounted in such a manner that the spaces between the blades are formed just like the shape of nozzles, as may be seen in the cross-sectional view. c. Cylinder. In impulse turbines with zero stage reaction, the total stage enthalpy is converted into 2. High rotational speed. Adjust the thrust generated by the turbine. 6.3. >>
e. Movement. c. Maximum blade efficiency. Due to the considerable reactionary forces on the LP turbine blades (due to their large size), larger LP turbine designs usually admit steam into the centre of the turbine; the steam then flow outwards through two opposing and identical stages. 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. The 100% reaction turbine is not practical because of the high rotor speed necessary for a good utilization factor. the moving d. Moving. b. There is therefore no contact between the moving and fixed portions except at the bearings. c. Atomization of the fuel. d. Only on condensing turbine e. 1st and 3rd. 2,3 High rotational speeds are required. 4.31). Introduction to Steam, Boilers and Thermodynamics, Introduction to Steam, Boilers and Thermodynamics (NV). b. A turbine with ahead and astern blading will have a dummy piston at either end to ensure balance in either direction of rotation. Another method often used in low-pressure turbines is to make the turbine double flow. d. 1,3,4 WebSteam turbine with dummy piston sealing arrangement for blocking saturated steam Classifications F01D3/04 Machines or engines with axial-thrust balancing effected by a. Velocity. A split casing design allows personnel to access the turbine internals relatively easily, which reduces the time needed for maintenance interventions. b. /Thumb 11 0 R 5. d. Petroleum process plant. Kinetic, useful. Fully balanced. e. Efficiency. The term rotor is often not clearly defined, which leads to some confusion concerning which components belong to the rotor. /Subtype /Image >> This pressure drop gives rise to a reaction in the opposite direction to that of added velocity. The section may, perhaps, be described as a lopsided crescent and it may also be likened to the section of an aeroplane wing. >> For this reason, a gearbox represents an additional potential failure mode. Pressure drops in the stationary blades a. If using a steam turbine to drive/rotate a ships propeller, there needs to be some way of driving it astern (reverse direction). Large boiler feedwater pumps are also often steam driven, which reduces the electrical load of the power plant whilst increasing the overall plant efficiency. b. Relieving pressure. a. Velocity, pressure. 1,2,3
However, non-condensing turbines are cheaper. a. a. 1. ), forms the rotor. c. 3,4 The blades are in section, and their shape and the nozzle-form passages between them are shown. the wheel. Least efficient. 2,3,4 Shipping Wonders of the World 2012-23 | Contents | Site Map | Contact Us | Cookie Policy, The modern marine steam turbine has been developed from the two main principles, reaction type and impulse type, invented respectively by Hero of Alexandria about AD 50 and by Giovanni Branca in 1629. On the right is the impulse machine designed by Giovanni Branca in 1629. Another outstanding feature of the Parsons turbine is the increase in size of the blades. Those at the low- pressure or exhaust end of the machine are much larger than those at the high- pressure end, into which steam is admitted from the boilers. 3,4 It is critical that turbines are very carefully warmed through when starting. The steam entering into the first set of moving blades imparts torque to the shaft due to a change in direction at the outlet and hence a change in momentum thereby impulse to the moving blades. /Kids [ 3 0 R 17 0 R 31 0 R 45 0 R 59 0 R ] /MediaBox [0 0 556.8 817.92] e. Pressure velocity compounding is created. 1, 2, 3. Decrease. Due to steam throttling loses, it is desirable to have steam throttle valves (sometimes called steam admission valves) either fully closed, or fully open, when the turbine is in operation. This clearly demonstrates why it is possible to use steam in a turbine at a pressure of 400 or even 550 lb superheated to a temperature of 750 degrees Fahrenheit. 4. A generator coupled on one shaft to a turbine consisting of two or more turbine in series is called a: d. Vary. Velocity decreases in the stationary blades Steam exits from the space between each segment and is discharged to the gland steam condenser; this setup increases the overall system efficiency. 1. The reaction turbine has a higher efficiency due to blade suction effects. c. Stationary. The standard setup is to have the drive end of the turbine fixed and stationary whilst the opposite end is free to move axially. The pads are arranged in a casing, radially for a thrust bearing, axially for a shaft bearing, and their construction enables them to tilt under the action of a revolving collar or shaft. b. Double Flow LP Turbine (shown on the right). a. Despite reaction turbines being classified as reaction, there is always a small degree of force imparted due to impulse. The disadvantages of a steam turbine include: Thin high temperature gaskets. 1. 1 0 obj Diesel engines are favoured because they do not require the large supporting water and steam systems that steam turbines require. This action has the effect of drawing a wedge-shaped film of oil between the moving surfaces.
The total difference between the inlet and exhaust steam pressure of a turbine is what ultimately determines its overall efficiency. b. Centrifugal. The effect of exit velocity and air angle on the utilization factor for a 50% reaction axial turbine stage. Cutting. It is this difference between the speed of entry and the speed of leaving that accounts for the work done in turning the wheel. b. If the process of stress relieving does not take place, physical distortion may occur as the temperature of the turbine varies e.g. The distinguishing feature of a reaction turbine is the fact that the pressure drop across the _____ blades. When steam leaves the moving blades at zero absolute velocity: 3. Little steam leaks past the knife-edges of the labyrinth, whose action is assisted by the shaft in carrying the steam round with it. /Resources << ScienceDirect is a registered trademark of Elsevier B.V. ScienceDirect is a registered trademark of Elsevier B.V. Comprehensive Renewable Energy (Second Edition), The Reaction Turbines Used in PHES Units and Related Problems, Source: Fig. Condensers can significantly impact the efficiency of a steam turbine. This axial clearance, as it is known, is made adjustable by a micrometer collar on the end of the turbine shaft. As we have already established, condensers have a negative effect on the system from an efficiency perspective, because we are rejecting heat. Register to licenses this file for a specified project. Contents 1 History 2 Manufacturing 3 Types 3.1 Blade and stage design 3.2 Blade design challenges e. Copper-nickel-bronze. b.
More efficient than built-up rotors. e. 2, 4. Press fitted. For power generation purposes, a typical condensing turbine may achieve operating efficiencies between 30-40%, compared to a non-condensing turbine which may achieve 15-35%. Cannot be made reversible endobj e. One set of nozzles and blades. b. Isothermal process. endobj 104 On start-up Where pressure compounding is adopted, the rings of fixed blades are omitted, and for them are substituted sets of nozzles which provide a drop in pressure with an increase of velocity. e. 50-55%. d. Carbon. What is the purpose of fixing a dummy piston and cylinder in steam turbine rotor? A gravity tank (or tanks) is installed at the top of the power plant building and oil is constantly circulated through the tank to maintain the desired level. As the turbine load increases, each nozzle bank moves from a fully closed to fully opened position, but only if the preceding nozzle bank is fully open. Because the steam issues from them much faster than it enters, the blades are given a kick or reaction-push. 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. Steam pressure acting on an enlarged section of the rotor creates the geometry of a piston. b. From the diagram W1 = V2, the angles of both the stationary and rotation blades are identical. e. Angular. c. Steam temperature. d. Volume, velocity. c. Measure axial position. It was the invention of specially-shaped reaction blading by Sir Charles Parsons that enabled this principle to be applied to the working of the steam turbine. Such a speed, however, renders the single-wheel impulse turbine unsuitable for marine propulsion and various means are adopted to use the velocity of the steam, so that it is spread over a number of bladed wheels revolving at a moderate pace. Moving blades are forged and then machined from single billets. a. The blading of such turbines is arranged at either end to face the central steam supply. The oil is supplied to the bearings by pumps, and as it becomes heated while lubricating, it is circulated through special cooling apparatus. To counteract the end thrust, the shaft in each casing is provided with a number of dummy pistons or unbladed disks. If the oil pressure decreases below a given setpoint, the emergency trip valve will actuate and the turbine will run to a standstill. Head 3,4 If the IP dummy ring is severely distorted, it is possible for the IP dummy leakage to be a mix of HP dummy leakage and HP exhaust steam flowing in the reverse c. Higher steam pressure use. >> The labyrinth gland comprises a series of plain grooves in the rotor shaft. b. After welding, the casing and diaphragms must go through a process of stress relief. Dipak K. Sarkar, in Thermal Power Plant, 2015. Rotor discs are mounted directly onto the rotor shaft, and rotor blades are mounted to the rotor discs. 19.10, P438, CH 19, Rotary Expanders and compressors, Power Plant Instrumentation and Control Handbook (Second Edition), Advanced industrial gas turbines for power generation, Combined Cycle Systems for Near-Zero Emission Power Generation, Hybrid Renewable Energy Systems and Microgrids, Fluid Mechanics and Thermodynamics of Turbomachinery (Seventh Edition), Renewable and Alternative Energy Resources, Efficient hydroenergy conversion technologies, challenges, and policy implication, Combination of impulse and reaction turbine, Fixed buckets at the periphery of the wheel, Runner vanes are fixed with the shaft so it cant be adjusted. e. Soft packing between each ring. WebTo counteract this force, steam is admitted to a dummy (balance) piston chamber at the low-pressure end of the rotor. Secondary. e. Shrink fitted and welded. Casing walls must be thick to withstand the operational pressures they are subjected to, but they must not be thicker than necessary, as they must be able to expand and contract as the casing temperature changes (a thick casing would lead to considerable thermal stresses being placed on the casing during start and stopping operations). Immediately it touches the revolving surface the match flies off sideways. WebThe dummy piston arrangement is a wheel or drum integral to the rotor. b.
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. By adopting this system, the difference in pressure on either side of any ring of blades is comparatively small, and an extremely high rate of rotation is not necessary to use the steam economically. Complete sentence with the correct medical specialty. a. Low level cavitation within condensate pumps may occur. 4. 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 _____. c. Stationary and moving blades. Figure 6.3. e. 2, 3. If axial thrust is balanced by double-flow turbine, turbine. It is reversible. So far as velocity of steam is concerned, it accelerates through the stator and decelerates through the rotor, with practically no net change in steam velocity across the stage but with a decrease in both pressure and temperature, reflecting the work performed in the spinning action of the rotor. Each cylinder is named based upon the steam inlet pressure associated with that particular cylinder, these are: Each cylinder type has a different diameter in order to accommodate the associated steam turbine rotor. e. Labyrinth seals. Tip If a thermocouple does detect water, it is often too late to prevent it entering the turbine unless the measuring points are located far away from the turbine itself. The resultant motive force is the vector sum of these impulse and reaction forces. c. 1,2,3 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. 1. Mr Parsonsbecame one of the founders of the power generation industry after he constructed an electrical generating set using a direct coupled steam turbine as the prime mover. e. Feed-water heating. No internal lubrication The fixed and the moving blades are arranged in this manner, but they face in opposite directions to effect reversal of the flow of steam. 2. To prevent the turbine rotor blades from moving outwards similarly and jamming in the casing, an ingenious method is adopted to fix them. The 50% reaction turbine has been used widely and has special significance. e. Low in capacity to weight ratio. Parallel to the rotational direction. 556.8 0 0 817.92 0 0 cm A reaction turbine has: Reduces the size of the thrust on impulse-reaction turbines. d. Topping turbine. Nozzle bank 3 will only begin to open if nozzle banks 1 and 2 are fully open, and only if the load on the turbine exceeds the amount of steam available through banks 1 and 2. In the rotor are cut a number of circular grooves of -section, and in the side walls of the s are cut several V-shaped grooves. d. Diaphragms. _____ turbines are large turbines with parallel shafts with a generator on each shaft. b. 4. (4.42), we may conclude that since the cross section of the flow at the end of the draft tube is bigger than that directly behind the turbine, Uw,5 has to be less than Uw,4. c. 1,3 As steam passes over a reaction turbine blade, a reactionary force is created upon the blade and this causes the turbine rotor to rotate. c. 1,2,3 Governor. To permit the required expansion of the steam, without change of temperature, special nozzles are used. Each blade must also be able to cope with the operational stresses placed upon it, these stresses include high temperature variations, high pressure variations, mechanical stresses from vibration, erosive effects of foreign object damage (water or rust particles etc. Keep the rotor in an exact position in the casing. The fixed blades act as nozzles. 3. steam from the boiler is fed directly to the HP turbine.
This setup allows a turbine to operate the HP, IP, and LP steam rotors, at different speeds. 2,3,5. The moving blades move as a result of the impulse of steam received (caused by a change in momentum) and also as a result of expansion and acceleration of the steam relative to them. b. /Type /Page Therefore, the static pressure decreases in both the fixed and moving blades. The rotor forms the central shaft of the turbine; it is installed along a horizontal axis through the centre of the turbine casing. This is overcome, however, by the use of a group of blading arranged for astern working which is attached to the rotor of one or more of the turbines comprising the set. c. 30-35%
It is important to constantly monitor the condenser condensate level, as too much condensate in the condenser hotwell may lead to several problems: Steam turbines are normally fitted with comprehensive monitoring and control systems. Impulse-reaction turbine schematic and pressure/velocity changes. Increase steam enthalpy 1. /Im0 Do Of its high capacity to weight ratio. c. On shut-down Figure2.40 shows a velocity diagram of a 50% reaction turbine and the effect on the utilization factor. To reduce these losses, most condensers are of the regenerative type. b. Pas plant. A steam turbine water seal is used _____ to insure that no air leaks The type of turbine that is more widely used than any other, especially for marine work, is the reaction turbine developed by the late Sir Charles Parsons. Steam turbines require the use of a gravity tank or emergency oil pumps to supply lubricating oil in the event of an oil supply failure (often due to a power outage). d. Isenthalpic process. a. c. Condensing turbine. The kinetic energy is regained by the conversion of water into suction head, thereby increasing the total pressure difference on the runner. d. square Two or more rows of moving blades. In ideal conditions the increases in size would be carried out gradually from one end of the turbine to the other; but, for convenience in construction, this is done in suitable steps or stages. In addition to housing the stationary blades, diaphragms form a pressure boundary that separates each of the pressure stages. A review and discussion of the recurrent problems experienced by reaction turbines is also presented to explain the main operating challenges for these machines due to the fluid dynamic phenomena perturbing the off-design operation and increasing the mechanical component damages. Fins and segments on the rotor shaft and casing create a torturous flow path for steam and air. e. At speeds above 2000 rev/mm. Make grooves for shaft seals. b. A smaller turbine to be used. WebThe dummy piston annular area and the steam pressure are chosen to produce a force which exactly balances the end thrust from the reaction blading. Copyright 2023 Elsevier B.V. or its licensors or contributors. This article discusses the history of steam turbines, their main components, designs, how they work, their associated system (oil, steam etc.) A major source of steam leakage is the dummy piston seal systems. e. 1,2,3,4. a. d. To be reheated in boiler. 2. c. 2,3,5 When the exit pressure of a steam turbine nozzle is less than _____ times the inlet pressure then a _____ nozzle will be used. Carbon rings, when used for turbine shaft seal require: The working process of the Kaplan turbine is similar to the propeller-type turbine along with adjustable runner blades so that it can work smoothly at vortices and shocks during partial load conditions. Schematic of a reaction type turbine showing the distribution of the thermodynamic and fluid mechanic properties. 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. Typical Power Generation Steam Turbine Installation. c. A force on the blades produced according to Newton's 2nd Law d. Lower limb 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. The blades are bucket-shaped in section and in general appearance resemble a woodworkers gouge. Of all the heat engines and prime movers the steam turbine is considered to be: steam. c. Mixed pressure. b. Couplings: Dummy piston arrangement on Parsons Turbines&Doubl End thrust is balanced removing need for dummy pistons or cylinders on reaction turbines . /Length 9 0 R Hence, the cost of a reaction turbine for the same amount of work is much higher, since it requires more stages. /Length 5 0 R Throttle valves should be periodically stroked/throttled to ensure freedom of movement on both the hydraulic and steam side. IP turbines are often installed within power stations but are not commonly used in other types of industrial plant. Carbon ring seals. c. Polytropic process. The rotor shaft and everything mounted to it (moving blades, rotor discs etc. 5. Nearest to the ideal. Due to their shape, they are referred to as cylinders as well as casings. Most gland seals operate at a pressure of approximately 0.25 bar (3.6 psi) and have make-up and spill valves to maintain the correct pressure irrespective of the turbines load condition.
6.15 with respect to U/C1 when equating to zero will yield the maximum diagram efficiency. THE smooth-cased turbine conveys to the uninitiated but little of its hidden might. The boilers provide the necessary steam for the steam turbine(s). c. Condensing-bleeder. Moving blades are responsible for transferring the heat energy from the steam to the rotor. Hall Ph.D., in Fluid Mechanics and Thermodynamics of Turbomachinery (Seventh Edition), 2014. e. Absolute. Due to the size and speed of the turbine, it may take the turbine several minutes until it comes to a standstill e.g. Housing diaphragms within the casing reduces the likelihood of axial movement of the diaphragms. Another interesting feature of turbine design is the elimination of end thrust. b. Normally, the lubrication oil system is connected to the control oil system, depending on the turbine design. The pipe is therefore narrowed down, providing correspondingly less space for the volume of steam. 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. Advantages of the steam turbine include: The end of the coiled paper tube, with its rush of lighted powder, is forced backwards by reaction and the catherine-wheel continues to revolve on its pin until the supply of explosive fuel is exhausted. Vendor balance Exhaust steam in a back-pressure turbine is not reduced to vacuum pressure, whereas a condenser turbine is. a. d. Condensing-bleeder.