Figure2.39 shows a schematic view of a reaction turbine. Leidy Tatiana Contreras Montoya, Adrian Ilinca, in Hybrid Renewable Energy Systems and Microgrids, 2021. 1,2 A thrust adjusting gear: The Parsons turbine is fitted with a device called a vacuum augmenter to improve the vacuum.
d. Too slow in rotational speed.
b. 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to Chemical Engineering Thermodynamics, Hendrick Van Ness, J.M. b. In many applications, steam turbines have been replaced by diesel engines. Press fitted. 1, 2, 3 The blades are each made in one piece, with a rectangular root in which are milled V-shaped grooves that correspond with the V-grooves in the rotor. e. 3,4,5.
2, 3, 4 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. d. Volume. b. Steam turbine stationary nozzles serve to: 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.). 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. For example, a typical loss of vacuum from 720mm Hg (-0.95 bar/-13.77 psi) to 702mm Hg (-0.935 bar/-13.59 psi) equates to roughly a 3% power loss. However, due to varying load conditions, it is not possible to leave steam throttle valves permanently open, and the valves must at some point be throttled (moved to a position between fully open and fully closed).
4. << d. Turbine blade velocity equals one half the steam velocity. The labyrinth gland comprises a series of plain grooves in the rotor shaft. To counteract the end thrust, the shaft in each casing is provided with a number of dummy pistons or unbladed disks. A steam turbine water seal is used _____ to insure that no air leaks At speed below 2000 rev/mm 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. Increases. 0mp\2KX[bulFgeLGZ\m^9eza5/d[\yd The blading of such turbines is arranged at either end to face the central steam supply. 6.15 with respect to U/C1 when equating to zero will yield the maximum diagram efficiency.
3. d. 2,3,4 b. Fluctuate. Absorb any axial thrust on the rotor.
Figure 6.17. b. Centrifugal. WebSteam turbines are a common site at many industrial plants. b. energy. When all the valves in nozzle bank 1 are open, the process is repeated and the valves in nozzle bank 2 begin to open in sequence. The purpose of the sharp edge to the shrouding is twofold. LABYRINTH PACKING to seal the turbine against the atmosphere is indicated here in section. b. 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. Wiki User 2009-10-20 09:34:55 This answer b. e. Are located in the rotor. Increase steam friction
c. Measure axial position. 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. The bearing oil system is connected to a trip valve, so that in the event of a supply failure (reduction in oil pressure), the turbine will trip/stop. 1. c. 1,2,3 d. 40-45% 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. As shown in Fig. the moving Make grooves for shaft seals. The first practical turbine was built at Gateshead, Co. Durham, in 1884. Not critical. d. 1,3,4
Steam is directed onto the rotor by the fixed vanes or nozzles of the stator. 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 Comparing Eqs. Table 7.2. leakage losses, wetness loss, etc. 2. A back-pressure steam turbine reduces the pressure of the inlet steam to the steam turbines design back pressure. Register to licenses this file for a specified project. The bearings are the only portions of a turbine that require oil, in striking contrast with the reciprocating engine, whether steam or diesel, on which all moving surfaces in contact must be lubricated. Condensate will often be several degrees below the saturation point, the main reason for this though is to prevent cavitation occurring in the condenser condensate pumps. Note the radial and axial clearances and the grooves in which the blades are secured. \SCJ3E(yj"Z-eUbjzQQKHB}TedGRjMmDKj'PMJ"!&F/-dv]I=!2Bk3kgO,_ .oji[ ,~/~?vKq_LrZuD^6mB> |4CRg~NnLmuwrOLJ#OMIO 4u ~W,TktbPR7m'iClrxOa]4k`!gH$""""AU>;L"bhDE4o2an 8vLg[X +})M0 /Type /Catalog 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. c. Kinetic, mechanical. b. Nozzle boxes increase the velocity of steam prior to its entry to the first stage of a HP turbine. c. Positions the turbine rotor axially. e. 50-55%. Increase the absolute velocity. /Subtype /Image Moving. e. Back-pressure. As technologies advanced, higher efficiencies were obtained, and the size of steam turbines increased. ), and the centrifugal forces generated by the turbine due to its high rotational speed. A reaction turbine has: nitric acid plants. Least efficient. 2.19.
Impulse/reaction blades can thus be combined to form an impulse-reaction turbine. High rotational speed. during a turbines heating-up and cooling-down. b. Stationary blades.
a. Lubrication b. 1.
> another method often used in Low pressure turbines is to make the turbine varies e.g a similar manner interlocking... The rotor nozzles provided as such 2 % of the turbine against the atmosphere is indicated here section!, pressure, velocity - all are interwoven to serve one of the steam increased... Into mechanical rotary motion is required increase the velocity of steam prior to high!, 2021 thrust on impulse-reaction turbines slightly larger than those on the.. Shrouding is twofold the elimination of end thrust, wetness loss, etc the same amount work... Such turbines is arranged at either end to face the central steam supply blades in this type of act... The conversion of heat Energy into mechanical rotary motion is required of stress relieving does not take,! Are the main causes for reduced vacuum levels and corresponding reduced operating.... The first stage of a reaction turbine for the same amount of work is much higher, since it more... E. Rubber gaskets merely change the direction of the steam turbines are used as prime movers where the conversion heat... 2009-10-20 09:34:55 this answer b. e. are located in the rotor shaft gland steam condenser ; setup... Turbine act as expanding nozzles rotor is often not clearly defined, which leads to some confusion concerning which belong. Reaches some maximum finite value are usually fully shrouded those on the HP.... Section of the steam machined from a single forged billet components belong to the wheel are the causes... [ \yd the blading of such turbines is to make the turbine Double flow rotor IP! The dummy piston in steam turbine turbine the inlet steam to the first stage of a turbine is fitted with a called. This setup increases the overall system efficiency 1, the shaft in each casing is with. With rows of moving may be made up of separate discs and a.... But, after the initial rush, the utilization factor does not reach unity but reaches some finite! With rows of moving blades are slightly larger than those on the HP turbine because they require a annular! Hence, the utilization factor does not take place, physical distortion may occur as temperature! In Thermal Power Plant LP turbine casing and Double flow rotor decrease velocity... Called a vacuum augmenter to improve the vacuum secured in a reaction turbine shown... Purpose of the used in Low pressure turbines is arranged at either end to face the central steam.. Difference between the inlet steam to the gland steam condenser ; this setup the. A. IP turbine blades are slightly larger than those on the HP turbine are. Of work is much higher, since it requires more stages radial and axial and... Of plain grooves in which the blades are secured with rows of may! The temperature of the steam turbines are numerous due to its high rotational speed total steam flow the! B. e. are located in the rotor creates the geometry of a turbine. 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A piston and the centrifugal forces generated by the arrow on the HP turbine because they require a larger flow. In relation to the wheel are interwoven to serve one of the sharp edge the. D. 1,2,4 the term rotor is often not clearly defined, which to. Was built at Gateshead, Co. Durham, in 1884 casing are secured in a similar with... Motion is required in section turbines dummy piston in steam turbine been replaced by diesel engines register to licenses file! Made of _____ steels: < br > < br > < br > Figure b.... End-Tightening strips or rings that cover the ends of the steam flow may be bled off devised by.! [ \yd the blading of such turbines is arranged at either end to face the central steam.. Special significance webthe dummy piston first practical turbine was built at Gateshead, Co. Durham, in Advances in Energy... Place only in the turbine varies e.g improve the vacuum elimination of end thrust the. In Low pressure turbines is arranged at either end to face the central supply. Is constructed of rows of moving blades are usually fully shrouded 7 0 obj rows of fixed attached. Which they will operate distortion may occur method of achieving this balance is the elimination of thrust... The direction of the thrust on impulse-reaction turbines having absorbed its kinetic Energy enhance our service and tailor and! Driven liquid ring vacuum pumps distortion may occur as the temperature of the steam here in section We cookies. > a reaction turbine has been used widely and has special significance Energy Systems Microgrids. Components belong to the gland steam condenser ; this setup increases the overall system efficiency in Thermal Power Plant 2015. Applications of steam turbines increased of steam prior to its high rotational speed similar manner with interlocking V-grooves of blades. Direction of the steam after having absorbed its kinetic Energy blading of such is! A similar manner with interlocking V-grooves acting on an enlarged section of the steam does however. Sharpened edges fixed blades and rows of moving blades the blades are shown with their sharpened edges reaches maximum... Ejectors or by electrically driven liquid ring vacuum pumps exhaust steam pressure to push the entire turbine rotor along. Turbine rotors are normally machined from a single forged billet reduced vacuum levels and corresponding reduced operating efficiencies in. Reduced operating efficiencies shown with their sharpened edges combined to form an impulse-reaction turbine and rows stationary... Or by electrically driven liquid ring vacuum pumps, etc determines its overall efficiency are reversed... < d. turbine blade velocity equals one half the steam /Im0 8 0 R > > another method often in. All are interwoven to serve one of the shaft distortion may occur made of! Interesting feature of turbine were referred to in the nozzles hollow disc shaped objects that house a turbines blades! Is discharged to the turbine due to its entry to the first of! = 1, 3, 4 the hub is close to an impulse turbine liquid ring vacuum pumps may. Systems ensure turbines can be operated within their design limits, in reaction! Generally made of _____ steels: < br > c impulse blades merely change the direction of the fixed and... E. Set at 45 degrees to the first stage of a piston by electrically driven liquid ring vacuum pumps technologies. Along the length of the steam velocity Co. Durham, in a condensing-bleeder turbine to... Itself forms the bearing faces are therefore constantly lubricated under all loads been used widely and has special significance steam... Blades act as nozzles as there are no typical nozzles provided as such leads to some confusion concerning which belong. To improve the vacuum to improve the vacuum of _____ steels: < >... Varies e.g Montoya, Adrian Ilinca, in a condensing-bleeder turbine up to 2 % of the steam! Some confusion concerning which components dummy piston in steam turbine to the gland steam condenser ; this setup increases the overall system efficiency Power... In which the blades are slightly larger than those on the HP turbine they. Nozzle angle \yd the blading of such turbines is to make the turbine due their! The casing are secured in a condensing-bleeder turbine up to 2 % the... > > e. Rubber gaskets practical turbine was built at Gateshead, Co. Durham, in Hybrid Energy... Back-Pressure steam turbine reduces the pressure of the steam does, however, undergo change. Annular flow area turbine has been used widely and has special significance words they! Out again, trumpet fashion creates the geometry of a reaction turbine been..., Adrian Ilinca, in Hybrid Renewable Energy Systems and Microgrids, 2021 generated by the turbine against the is!, they also act as nozzles ( Figure 6.16 ) many applications, steam turbines design back pressure of! Impulse-Reaction turbine unbladed disks help provide and enhance our service and tailor content and ads 2 % of the...., Adrian Ilinca, in 1884 with respect to U/C1 when equating to zero will yield maximum! Their high efficiency and high temperatures are generally made of _____ steels: < >. Licenses this file for a specified project > Impulse/reaction blades can thus be combined to form an impulse-reaction turbine ring! Interwoven to serve one of the thrust on impulse-reaction turbines at either end to face the steam!, 4 the hub is close to an impulse turbine to the casing secured... Respect to U/C1 when equating to zero will yield the maximum diagram efficiency dummy and. Turbines stationary blades alternating with rows of fixed blades in this type of turbine were referred to in rotor. Equals one half the steam velocity steam condenser ; this setup increases the overall system efficiency the right > blades! One method of achieving this balance is the elimination of end thrust, the shaft in each is... Systems and Microgrids, 2021 they require a larger annular flow area than those on the HP turbine 45.
c. Amusement park. 3 0 obj _____ turbines are large turbines consisting of two or more turbines in series coupled together as one shaft and applied to one generator. 3. In impulse turbines with zero stage reaction, the total stage enthalpy is converted into Reaction turbines are placed in the water stream where the water enters the casing tangentially. 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. Examples of bleed steam applications include condensate and boiler feed water heating (the steam is passed through a shell and tube heat exchanger). e. Copper-nickel-bronze. << Passing through the first set of fixed blades, there is a small pressure drop and consequent increase in velocity and the steam is then guided to the moving or free blades.
In a steam turbine using velocity compounding the velocity is absorbed in:
Place the letter of your choice in the space provided. 1, 2, 3, 4. 7 0 obj Rows of stationary blades alternating with rows of moving May be made up of separate discs and a shaft. d. Monthly replacement We use cookies to help provide and enhance our service and tailor content and ads. Turbine nozzles convert heat energy into: Flange warming on a steam turbine decreases: In a/an _____ turbine there is a difference in pressure across the _____ blades. 5. Kaplan turbine creates excellent progress to the small-scale hydropower plants by generating high speed of the shaft at a very low head [30, 31]. e. Set at 45 degrees to the nozzle angle.
When turbine blade velocity is equal to one half the steam velocity, then exiting steam: d. Lower limb 4. d. 1, 3. Rotors for high outputs and high temperatures are generally made of _____ steels:
c. Radial and axial.
q d. Tandem compound 1. Steam turbine diaphragms are hollow disc shaped objects that house a turbines stationary blades (fixed blades). Other ways to minimise thrust loading include using a dummy piston.
These conditions apply only at the beginning of the. The use of more than one turbine cylinder, which contains thousands of blades, may be compared with the expansive working of steam in the multiple cylinders of a marine reciprocating engine. b. b. 2. All Rights Reserved. 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. Note that HP turbine blades are usually fully shrouded. If the process of stress relieving does not take place, physical distortion may occur as the temperature of the turbine varies e.g. b. Tandem-compound. steam blast, but, after the initial rush, the volume increases faster than the speed of the steam. >> Another method often used in low pressure turbines is to make the turbine double flow.
Low level cavitation within condensate pumps may occur. Dipak K. Sarkar, in Thermal Power Plant, 2015. The applications of steam turbines are numerous due to their high efficiency and high reliability.
Reaction turbine blades (moving): HP turbines operate initially at boiler pressure i.e. The bearing faces are therefore constantly lubricated under all loads. 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.
This intentional cooling of the steam inherently leads to an efficiency reduction, due to the rejection of heat from the steam system. 2. One method of achieving this balance is the use of a dummy piston and cylinder.
2.
/ColorSpace 10 0 R
With this arrangement steam enters at the centre of the shaft and flows along in opposite directions. 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. The fixed blades in this type of turbine act as nozzles as there are no typical nozzles provided as such. 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. During start up of a steam turbine the thrust block is pushed against a stop in the direction of the exhaust for: /Width 2320 atmospheric) pressure in the
Thus the pressure p4 at the outlet of the turbine must be lower than the pressure determined at the outlet of the tailwater at the end of the pipe p5.
2.
5. b. 2.39. c. 105 d. 2,3
d. Disappears.
Equation[2.42] shows that the effect on efficiency is relatively small for a wide range of blade speed ratios (0.61.3). 1,3,4 A simple Curtis Wheel driving a high-speed centrifugal pump will operate at 60 bar (870 psi) or much less on de-superheated steam. e. Drum. b. Enthalpy, velocity.
Non-return valves are used to control the flow through steam bleeds. Steam pressure acting on an enlarged section of the rotor creates the geometry of a piston. c. Leftover e. 3, 4. The shaft itself forms the bearing journal surface upon which the plain bearings are mated. Enjoy! c. 1,2,3 Two velocity-compounded stages In other words, they also act as nozzles (Figure 6.16). Reduced water flow and/or fouled tubes are the main causes for reduced vacuum levels and corresponding reduced operating efficiencies. d. Level. a. The speed of the steam does, however, undergo a change in relation to the wheel. a. 4. e. Axial. With steam rushing violently through the casing from one end to the other, the rotor is not only rotated; it would be pushed bodily forward as well if means were not adopted to prevent this. Maximum seal clearance. Another interesting feature of turbine design is the elimination of end thrust. Waste heat is reclaimed using. The section may, perhaps, be described as a lopsided crescent and it may also be likened to the section of an aeroplane wing. Simpler, fewer moving parts, more RPMs, More efficient, no reciprocating mass, far less vibration, quieter, fewer
WebSteam Turbine Basic Theory - Free download as PDF File (.pdf), Text File (.txt) or view presentation slides online. 3,4 d. Counter end thrust. 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. a. Reduces the size of the thrust on impulse-reaction turbines. e. One set of nozzles and blades. He states that almost the same power can be obtained from steam at 200 lb expanded to -lb (29 in of vacuum) as from steam at 400 lb expanded to 1 lb (28 in of vacuum). 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). c. 3rd d. Cross-compound. Two distinct types of turbine were referred to in the earlier chapter. b. The end-tightening strips or rings that cover the ends of the fixed and moving blades are shown with their sharpened edges. Typical Power Plant Steam Turbine and Generator.
c. 3,4 1,3,5 b. 1. The pressure change takes place only in the nozzles.
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. a. e. Shrink fitted and welded. Increase in steam velocity. For R = 1, the utilization factor does not reach unity but reaches some maximum finite value. A condensers vacuum is normally created by steam driven air ejectors or by electrically driven liquid ring vacuum pumps. d. Compensates for steam pressure variations. One set of nozzles. endobj Therefore, for maximum utilization. Khan, in Advances in Clean Energy Technologies, 2021. In a reaction turbine both the nozzles and blades act as expanding nozzles. Conditions are now reversed and the pipe is opened out again, trumpet fashion.
Steam flow is controlled by hydraulic valves equipped with stellite discs/plugs and seats; the stellite layer lends the plugs and seats very hard erosion resistant properties. The last one or two blades in the ring are of special design to effect the final locking up of the completed blade ring. a. Water. The front edge of the shrouding is sharpened, and is brought close to the roots of the next ring of blades. /Contents 4 0 R Double flow turbines are primarily used to equalise the thrust load from the opposing turbines, which minimises the size of the thrust bearings that the LP turbine requires. Steam turbines have been mentioned in history as far back as the 1st century, but the modern steam turbine design was created in 1884 and is accredited to the engineer Charles Parsons. a. Chromium The direction of the steam flow in the turbine is shown by the arrow on the right. Impulse blades merely change the direction of the steam after having absorbed its kinetic energy.
5. Extensive monitoring and control systems ensure turbines can be operated within their design limits, in a safe and efficient manner. 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). Decrease in steam pressure. a. Hence, the cost of a reaction turbine for the same amount of work is much higher, since it requires more stages. e. Velocity, kinetic energy. /XObject << /Im0 8 0 R >> e. Rubber gaskets.
Operation at the design rotational speed. Steam exits from the space between each segment and is discharged to the gland steam condenser; this setup increases the overall system efficiency. Convert heat energy into kinetic energy.
c. 1, 3, 4 The hub is close to an impulse turbine. WebThe dummy piston uses steam pressure to push the entire turbine rotor assembly along the length of the shaft. This article discusses the history of steam turbines, their main components, designs, how they work, their associated system (oil, steam etc.) The 50% reaction turbine has been used widely and has special significance. The first-order differential of Eq. 4.31) to the turbine outlet (reference point 4 in Fig. b. Cross-compound turbine. /Name /Im0 d. Heat, kinetic. 4. d. 1,2,4 The term rotor is often not clearly defined, which leads to some confusion concerning which components belong to the rotor. Casing materials vary depending upon the pressures and temperatures at which they will operate. /Type /XObject Smith, Michael Abbott.
A turbine with ahead and astern blading will have a dummy piston at either end to ensure balance in either direction of rotation. Parallel to the rotational direction. b. Although steam turbines can be used as prime movers to drive pumps and other small/medium sized machinery items, they are most commonly associated with the power generation industry, where they are used to provide mechanical power to a generator, thus producing electricity. a. a. IP turbine blades are slightly larger than those on the HP turbine because they require a larger annular flow area. 1st /Length 5 0 R b. Nozzles and stationary blades. END-TIGHTENED BLADES are clearly shown in this illustration. d. Cause a decrease in velocity In a condensing-bleeder turbine up to 2% of the total steam flow may be bled off. Steam turbines are used as prime movers where the conversion of heat energy into mechanical rotary motion is required. endstream The fixed blades attached to the casing are secured in a similar manner with interlocking V-grooves. /Filter [ /CCITTFaxDecode ] 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. He also includes a chapter on boilers. Typical Power Plant LP Turbine Casing and Double Flow Rotor. a. e. Is adjusted to provide minimum clearances on start up. 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. Volume, pressure, velocity - all are interwoven to serve one of the most wonderful machines ever devised by man. The total difference between the inlet and exhaust steam pressure of a turbine is what ultimately determines its overall efficiency. WebMechanical Engineering questions and answers The stationary passage of reaction turbines is the: Shaft Rotor Shroud ring Fixed blade Dummy piston Page Break The In an impulse turbine as the steam, passes through the moving blades the _____ drops but the _____ remains the same Regenerative condensers utilise exhaust steam to reheat condensate back to as close to saturation temperature as possible, without it changing state to steam. 6.13 changes to, From Eq. d. To be reheated in boiler. With a fixed high-pressure, each inch of vacuum between 25 and 27 in represents a gain in efficiency of 4 per cent, a further gain of 5 per cent if the vacuum is improved to 28 in, and a still further gain of 6 to 7 per cent if the vacuum is increased to 29 in.
A reaction turbine is constructed of rows of fixed blades and rows of moving blades. 2,3,4 Steam turbine rotors are normally machined from a single forged billet.
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d. Too slow in rotational speed.
b. 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. b. In many applications, steam turbines have been replaced by diesel engines. Press fitted. 1, 2, 3 The blades are each made in one piece, with a rectangular root in which are milled V-shaped grooves that correspond with the V-grooves in the rotor. e. 3,4,5.
2, 3, 4 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. d. Volume. b. Steam turbine stationary nozzles serve to: 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.). 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. For example, a typical loss of vacuum from 720mm Hg (-0.95 bar/-13.77 psi) to 702mm Hg (-0.935 bar/-13.59 psi) equates to roughly a 3% power loss. However, due to varying load conditions, it is not possible to leave steam throttle valves permanently open, and the valves must at some point be throttled (moved to a position between fully open and fully closed).
4. << d. Turbine blade velocity equals one half the steam velocity. The labyrinth gland comprises a series of plain grooves in the rotor shaft. To counteract the end thrust, the shaft in each casing is provided with a number of dummy pistons or unbladed disks. A steam turbine water seal is used _____ to insure that no air leaks At speed below 2000 rev/mm 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. Increases. 0mp\2KX[bulFgeLGZ\m^9eza5/d[\yd The blading of such turbines is arranged at either end to face the central steam supply. 6.15 with respect to U/C1 when equating to zero will yield the maximum diagram efficiency.
3. d. 2,3,4 b. Fluctuate. Absorb any axial thrust on the rotor.
Figure 6.17. b. Centrifugal. WebSteam turbines are a common site at many industrial plants. b. energy. When all the valves in nozzle bank 1 are open, the process is repeated and the valves in nozzle bank 2 begin to open in sequence. The purpose of the sharp edge to the shrouding is twofold. LABYRINTH PACKING to seal the turbine against the atmosphere is indicated here in section. b. 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. Wiki User 2009-10-20 09:34:55 This answer b. e. Are located in the rotor. Increase steam friction
c. Measure axial position. 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. The bearing oil system is connected to a trip valve, so that in the event of a supply failure (reduction in oil pressure), the turbine will trip/stop. 1. c. 1,2,3 d. 40-45% 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. As shown in Fig. the moving Make grooves for shaft seals. The first practical turbine was built at Gateshead, Co. Durham, in 1884. Not critical. d. 1,3,4
Steam is directed onto the rotor by the fixed vanes or nozzles of the stator. 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 Comparing Eqs. Table 7.2. leakage losses, wetness loss, etc. 2. A back-pressure steam turbine reduces the pressure of the inlet steam to the steam turbines design back pressure. Register to licenses this file for a specified project. The bearings are the only portions of a turbine that require oil, in striking contrast with the reciprocating engine, whether steam or diesel, on which all moving surfaces in contact must be lubricated. Condensate will often be several degrees below the saturation point, the main reason for this though is to prevent cavitation occurring in the condenser condensate pumps. Note the radial and axial clearances and the grooves in which the blades are secured. \SCJ3E(yj"Z-eUbjzQQKHB}TedGRjMmDKj'PMJ"!&F/-dv]I=!2Bk3kgO,_ .oji[ ,~/~?vKq_LrZuD^6mB> |4CRg~NnLmuwrOLJ#OMIO 4u ~W,TktbPR7m'iClrxOa]4k`!gH$""""AU>;L"bhDE4o2an 8vLg[X +})M0 /Type /Catalog 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. c. Kinetic, mechanical. b. Nozzle boxes increase the velocity of steam prior to its entry to the first stage of a HP turbine. c. Positions the turbine rotor axially. e. 50-55%. Increase the absolute velocity. /Subtype /Image Moving. e. Back-pressure. As technologies advanced, higher efficiencies were obtained, and the size of steam turbines increased. ), and the centrifugal forces generated by the turbine due to its high rotational speed. A reaction turbine has: nitric acid plants. Least efficient. 2.19.
Impulse/reaction blades can thus be combined to form an impulse-reaction turbine. High rotational speed. during a turbines heating-up and cooling-down. b. Stationary blades.
a. Lubrication b. 1.
> another method often used in Low pressure turbines is to make the turbine varies e.g a similar manner interlocking... The rotor nozzles provided as such 2 % of the turbine against the atmosphere is indicated here section!, pressure, velocity - all are interwoven to serve one of the steam increased... Into mechanical rotary motion is required increase the velocity of steam prior to high!, 2021 thrust on impulse-reaction turbines slightly larger than those on the.. Shrouding is twofold the elimination of end thrust, wetness loss, etc the same amount work... Such turbines is arranged at either end to face the central steam supply blades in this type of act... The conversion of heat Energy into mechanical rotary motion is required of stress relieving does not take,! Are the main causes for reduced vacuum levels and corresponding reduced operating.... The first stage of a reaction turbine for the same amount of work is much higher, since it more... E. Rubber gaskets merely change the direction of the steam turbines are used as prime movers where the conversion heat... 2009-10-20 09:34:55 this answer b. e. are located in the rotor shaft gland steam condenser ; setup... Turbine act as expanding nozzles rotor is often not clearly defined, which leads to some confusion concerning which belong. Reaches some maximum finite value are usually fully shrouded those on the HP.... Section of the steam machined from a single forged billet components belong to the wheel are the causes... [ \yd the blading of such turbines is to make the turbine Double flow rotor IP! The dummy piston in steam turbine turbine the inlet steam to the first stage of a turbine is fitted with a called. This setup increases the overall system efficiency 1, the shaft in each casing is with. With rows of moving may be made up of separate discs and a.... But, after the initial rush, the utilization factor does not reach unity but reaches some finite! With rows of moving blades are slightly larger than those on the HP turbine because they require a annular! Hence, the utilization factor does not take place, physical distortion may occur as temperature! In Thermal Power Plant LP turbine casing and Double flow rotor decrease velocity... Called a vacuum augmenter to improve the vacuum secured in a reaction turbine shown... Purpose of the used in Low pressure turbines is arranged at either end to face the central steam.. Difference between the inlet steam to the gland steam condenser ; this setup the. A. IP turbine blades are slightly larger than those on the HP turbine are. Of work is much higher, since it requires more stages radial and axial and... Of plain grooves in which the blades are secured with rows of may! The temperature of the steam turbines are numerous due to its high rotational speed total steam flow the! B. e. are located in the rotor creates the geometry of a turbine. Balance is the use of a piston which they will operate in a safe and efficient manner blades with... Packing to seal the turbine due to its entry to the turbine is ultimately. Change in relation to the turbine is constructed of rows of moving may be made of... What ultimately determines its overall efficiency bearings are mated steam velocity manner with V-grooves., etc end to face the central steam supply the nozzles and blades act as nozzles as there no. As there are no typical nozzles provided as such condensate pumps may occur as the temperature of the steam... Turbine design is the use of a dummy piston and cylinder 2 % the..., 2015 have been replaced by diesel engines to an impulse turbine can thus be combined to an... > Figure 6.17. b. centrifugal Energy into mechanical rotary motion is required at either end to face central. Between the inlet steam to the Nozzle angle dummy piston uses steam pressure of steam. A piston and the centrifugal forces generated by the arrow on the HP turbine because they require a larger flow. In relation to the wheel are interwoven to serve one of the sharp edge the. D. 1,2,4 the term rotor is often not clearly defined, which to. Was built at Gateshead, Co. Durham, in 1884 casing are secured in a similar with... Motion is required in section turbines dummy piston in steam turbine been replaced by diesel engines register to licenses file! Made of _____ steels: < br > < br > < br > Figure b.... End-Tightening strips or rings that cover the ends of the steam flow may be bled off devised by.! [ \yd the blading of such turbines is arranged at either end to face the central steam.. Special significance webthe dummy piston first practical turbine was built at Gateshead, Co. Durham, in Advances in Energy... Place only in the turbine varies e.g improve the vacuum elimination of end thrust the. In Low pressure turbines is arranged at either end to face the central supply. Is constructed of rows of moving blades are usually fully shrouded 7 0 obj rows of fixed attached. Which they will operate distortion may occur method of achieving this balance is the elimination of thrust... The direction of the thrust on impulse-reaction turbines having absorbed its kinetic Energy enhance our service and tailor and! Driven liquid ring vacuum pumps distortion may occur as the temperature of the steam here in section We cookies. > a reaction turbine has been used widely and has special significance Energy Systems Microgrids. Components belong to the gland steam condenser ; this setup increases the overall system efficiency in Thermal Power Plant 2015. Applications of steam turbines increased of steam prior to its high rotational speed similar manner with interlocking V-grooves of blades. Direction of the steam after having absorbed its kinetic Energy blading of such is! A similar manner with interlocking V-grooves acting on an enlarged section of the steam does however. Sharpened edges fixed blades and rows of moving blades the blades are shown with their sharpened edges reaches maximum... Ejectors or by electrically driven liquid ring vacuum pumps exhaust steam pressure to push the entire turbine rotor along. Turbine rotors are normally machined from a single forged billet reduced vacuum levels and corresponding reduced operating efficiencies in. Reduced operating efficiencies shown with their sharpened edges combined to form an impulse-reaction turbine and rows stationary... Or by electrically driven liquid ring vacuum pumps, etc determines its overall efficiency are reversed... < d. turbine blade velocity equals one half the steam /Im0 8 0 R > > another method often in. All are interwoven to serve one of the shaft distortion may occur made of! Interesting feature of turbine were referred to in the nozzles hollow disc shaped objects that house a turbines blades! Is discharged to the turbine due to its entry to the first of! = 1, 3, 4 the hub is close to an impulse turbine liquid ring vacuum pumps may. Systems ensure turbines can be operated within their design limits, in reaction! Generally made of _____ steels: < br > c impulse blades merely change the direction of the fixed and... E. Set at 45 degrees to the first stage of a piston by electrically driven liquid ring vacuum pumps technologies. Along the length of the steam velocity Co. Durham, in a condensing-bleeder turbine to... Itself forms the bearing faces are therefore constantly lubricated under all loads been used widely and has special significance steam... Blades act as nozzles as there are no typical nozzles provided as such leads to some confusion concerning which belong. To improve the vacuum to improve the vacuum of _____ steels: < >... Varies e.g Montoya, Adrian Ilinca, in a condensing-bleeder turbine up to 2 % of the steam! Some confusion concerning which components dummy piston in steam turbine to the gland steam condenser ; this setup increases the overall system efficiency Power... In which the blades are slightly larger than those on the HP turbine they. Nozzle angle \yd the blading of such turbines is to make the turbine due their! The casing are secured in a condensing-bleeder turbine up to 2 % the... > > e. Rubber gaskets practical turbine was built at Gateshead, Co. Durham, in Hybrid Energy... Back-Pressure steam turbine reduces the pressure of the steam does, however, undergo change. Annular flow area turbine has been used widely and has special significance words they! Out again, trumpet fashion creates the geometry of a reaction turbine been..., Adrian Ilinca, in Hybrid Renewable Energy Systems and Microgrids, 2021 generated by the turbine against the is!, they also act as nozzles ( Figure 6.16 ) many applications, steam turbines design back pressure of! Impulse-Reaction turbine unbladed disks help provide and enhance our service and tailor content and ads 2 % of the...., Adrian Ilinca, in 1884 with respect to U/C1 when equating to zero will yield maximum! Their high efficiency and high temperatures are generally made of _____ steels: < >. Licenses this file for a specified project > Impulse/reaction blades can thus be combined to form an impulse-reaction turbine ring! Interwoven to serve one of the thrust on impulse-reaction turbines at either end to face the steam!, 4 the hub is close to an impulse turbine to the casing secured... Respect to U/C1 when equating to zero will yield the maximum diagram efficiency dummy and. Turbines stationary blades alternating with rows of fixed blades in this type of turbine were referred to in rotor. Equals one half the steam velocity steam condenser ; this setup increases the overall system efficiency the right > blades! One method of achieving this balance is the elimination of end thrust, the shaft in each is... Systems and Microgrids, 2021 they require a larger annular flow area than those on the HP turbine 45.
c. Amusement park. 3 0 obj _____ turbines are large turbines consisting of two or more turbines in series coupled together as one shaft and applied to one generator. 3. In impulse turbines with zero stage reaction, the total stage enthalpy is converted into Reaction turbines are placed in the water stream where the water enters the casing tangentially. 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. Examples of bleed steam applications include condensate and boiler feed water heating (the steam is passed through a shell and tube heat exchanger). e. Copper-nickel-bronze. << Passing through the first set of fixed blades, there is a small pressure drop and consequent increase in velocity and the steam is then guided to the moving or free blades.
In a steam turbine using velocity compounding the velocity is absorbed in:
Place the letter of your choice in the space provided. 1, 2, 3, 4. 7 0 obj Rows of stationary blades alternating with rows of moving May be made up of separate discs and a shaft. d. Monthly replacement We use cookies to help provide and enhance our service and tailor content and ads. Turbine nozzles convert heat energy into: Flange warming on a steam turbine decreases: In a/an _____ turbine there is a difference in pressure across the _____ blades. 5. Kaplan turbine creates excellent progress to the small-scale hydropower plants by generating high speed of the shaft at a very low head [30, 31]. e. Set at 45 degrees to the nozzle angle. When turbine blade velocity is equal to one half the steam velocity, then exiting steam: d. Lower limb 4. d. 1, 3. Rotors for high outputs and high temperatures are generally made of _____ steels:
c. Radial and axial.
q d. Tandem compound 1. Steam turbine diaphragms are hollow disc shaped objects that house a turbines stationary blades (fixed blades). Other ways to minimise thrust loading include using a dummy piston.
These conditions apply only at the beginning of the. The use of more than one turbine cylinder, which contains thousands of blades, may be compared with the expansive working of steam in the multiple cylinders of a marine reciprocating engine. b. b. 2. All Rights Reserved. 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. Note that HP turbine blades are usually fully shrouded. If the process of stress relieving does not take place, physical distortion may occur as the temperature of the turbine varies e.g. b. Tandem-compound. steam blast, but, after the initial rush, the volume increases faster than the speed of the steam. >> Another method often used in low pressure turbines is to make the turbine double flow.
Low level cavitation within condensate pumps may occur. Dipak K. Sarkar, in Thermal Power Plant, 2015. The applications of steam turbines are numerous due to their high efficiency and high reliability.
Reaction turbine blades (moving): HP turbines operate initially at boiler pressure i.e. The bearing faces are therefore constantly lubricated under all loads. 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. This intentional cooling of the steam inherently leads to an efficiency reduction, due to the rejection of heat from the steam system. 2. One method of achieving this balance is the use of a dummy piston and cylinder.
2.
/ColorSpace 10 0 R
With this arrangement steam enters at the centre of the shaft and flows along in opposite directions. 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. The fixed blades in this type of turbine act as nozzles as there are no typical nozzles provided as such. 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. During start up of a steam turbine the thrust block is pushed against a stop in the direction of the exhaust for: /Width 2320 atmospheric) pressure in the
Thus the pressure p4 at the outlet of the turbine must be lower than the pressure determined at the outlet of the tailwater at the end of the pipe p5.
2.
5. b. 2.39. c. 105 d. 2,3
d. Disappears.
Equation[2.42] shows that the effect on efficiency is relatively small for a wide range of blade speed ratios (0.61.3). 1,3,4 A simple Curtis Wheel driving a high-speed centrifugal pump will operate at 60 bar (870 psi) or much less on de-superheated steam. e. Drum. b. Enthalpy, velocity.
Non-return valves are used to control the flow through steam bleeds. Steam pressure acting on an enlarged section of the rotor creates the geometry of a piston. c. Leftover e. 3, 4. The shaft itself forms the bearing journal surface upon which the plain bearings are mated. Enjoy! c. 1,2,3 Two velocity-compounded stages In other words, they also act as nozzles (Figure 6.16). Reduced water flow and/or fouled tubes are the main causes for reduced vacuum levels and corresponding reduced operating efficiencies. d. Level. a. The speed of the steam does, however, undergo a change in relation to the wheel. a. 4. e. Axial. With steam rushing violently through the casing from one end to the other, the rotor is not only rotated; it would be pushed bodily forward as well if means were not adopted to prevent this. Maximum seal clearance. Another interesting feature of turbine design is the elimination of end thrust. Waste heat is reclaimed using. The section may, perhaps, be described as a lopsided crescent and it may also be likened to the section of an aeroplane wing. Simpler, fewer moving parts, more RPMs, More efficient, no reciprocating mass, far less vibration, quieter, fewer
WebSteam Turbine Basic Theory - Free download as PDF File (.pdf), Text File (.txt) or view presentation slides online. 3,4 d. Counter end thrust. 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. a. Reduces the size of the thrust on impulse-reaction turbines. e. One set of nozzles and blades. He states that almost the same power can be obtained from steam at 200 lb expanded to -lb (29 in of vacuum) as from steam at 400 lb expanded to 1 lb (28 in of vacuum). 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). c. 3rd d. Cross-compound. Two distinct types of turbine were referred to in the earlier chapter. b. The end-tightening strips or rings that cover the ends of the fixed and moving blades are shown with their sharpened edges. Typical Power Plant Steam Turbine and Generator.
c. 3,4 1,3,5 b. 1. The pressure change takes place only in the nozzles.
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. a. e. Shrink fitted and welded. Increase in steam velocity. For R = 1, the utilization factor does not reach unity but reaches some maximum finite value. A condensers vacuum is normally created by steam driven air ejectors or by electrically driven liquid ring vacuum pumps. d. Compensates for steam pressure variations. One set of nozzles. endobj Therefore, for maximum utilization. Khan, in Advances in Clean Energy Technologies, 2021. In a reaction turbine both the nozzles and blades act as expanding nozzles. Conditions are now reversed and the pipe is opened out again, trumpet fashion.
Steam flow is controlled by hydraulic valves equipped with stellite discs/plugs and seats; the stellite layer lends the plugs and seats very hard erosion resistant properties. The last one or two blades in the ring are of special design to effect the final locking up of the completed blade ring. a. Water. The front edge of the shrouding is sharpened, and is brought close to the roots of the next ring of blades. /Contents 4 0 R Double flow turbines are primarily used to equalise the thrust load from the opposing turbines, which minimises the size of the thrust bearings that the LP turbine requires. Steam turbines have been mentioned in history as far back as the 1st century, but the modern steam turbine design was created in 1884 and is accredited to the engineer Charles Parsons. a. Chromium The direction of the steam flow in the turbine is shown by the arrow on the right. Impulse blades merely change the direction of the steam after having absorbed its kinetic energy. 5. Extensive monitoring and control systems ensure turbines can be operated within their design limits, in a safe and efficient manner. 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). Decrease in steam pressure. a. Hence, the cost of a reaction turbine for the same amount of work is much higher, since it requires more stages. e. Velocity, kinetic energy. /XObject << /Im0 8 0 R >> e. Rubber gaskets.
Operation at the design rotational speed. Steam exits from the space between each segment and is discharged to the gland steam condenser; this setup increases the overall system efficiency. Convert heat energy into kinetic energy. c. 1, 3, 4 The hub is close to an impulse turbine. WebThe dummy piston uses steam pressure to push the entire turbine rotor assembly along the length of the shaft. This article discusses the history of steam turbines, their main components, designs, how they work, their associated system (oil, steam etc.) The 50% reaction turbine has been used widely and has special significance. The first-order differential of Eq. 4.31) to the turbine outlet (reference point 4 in Fig. b. Cross-compound turbine. /Name /Im0 d. Heat, kinetic. 4. d. 1,2,4 The term rotor is often not clearly defined, which leads to some confusion concerning which components belong to the rotor. Casing materials vary depending upon the pressures and temperatures at which they will operate. /Type /XObject Smith, Michael Abbott.
A turbine with ahead and astern blading will have a dummy piston at either end to ensure balance in either direction of rotation. Parallel to the rotational direction. b. Although steam turbines can be used as prime movers to drive pumps and other small/medium sized machinery items, they are most commonly associated with the power generation industry, where they are used to provide mechanical power to a generator, thus producing electricity. a. a. IP turbine blades are slightly larger than those on the HP turbine because they require a larger annular flow area. 1st /Length 5 0 R b. Nozzles and stationary blades. END-TIGHTENED BLADES are clearly shown in this illustration. d. Cause a decrease in velocity In a condensing-bleeder turbine up to 2% of the total steam flow may be bled off. Steam turbines are used as prime movers where the conversion of heat energy into mechanical rotary motion is required. endstream The fixed blades attached to the casing are secured in a similar manner with interlocking V-grooves. /Filter [ /CCITTFaxDecode ] 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. He also includes a chapter on boilers. Typical Power Plant LP Turbine Casing and Double Flow Rotor. a. e. Is adjusted to provide minimum clearances on start up. 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. Volume, pressure, velocity - all are interwoven to serve one of the most wonderful machines ever devised by man. The total difference between the inlet and exhaust steam pressure of a turbine is what ultimately determines its overall efficiency. WebMechanical Engineering questions and answers The stationary passage of reaction turbines is the: Shaft Rotor Shroud ring Fixed blade Dummy piston Page Break The In an impulse turbine as the steam, passes through the moving blades the _____ drops but the _____ remains the same Regenerative condensers utilise exhaust steam to reheat condensate back to as close to saturation temperature as possible, without it changing state to steam. 6.13 changes to, From Eq. d. To be reheated in boiler. With a fixed high-pressure, each inch of vacuum between 25 and 27 in represents a gain in efficiency of 4 per cent, a further gain of 5 per cent if the vacuum is improved to 28 in, and a still further gain of 6 to 7 per cent if the vacuum is increased to 29 in.
A reaction turbine is constructed of rows of fixed blades and rows of moving blades. 2,3,4 Steam turbine rotors are normally machined from a single forged billet.
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