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71 Cards in this Set
- Front
- Back
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Turbine nozzles convert heat energy into
a) potential energy b) enthalpy c) eddy-currents d) kinetic energy e) pressure |
d) kinetic energy |
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Labyrinth seals are: 1) made of cast iron 2) a positive leak-proof seal arrangement 3) design to have large clearances between the shaft and casing 4) made of brass or stainless steel 5) used on larger diameter turbines shafts |
4, 5 |
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Flange warming on a steam turbine decreases a) creep b) start up time c) movement d) radiation losses |
b) start up time |
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In pressure compounded steam turbines 1. the expansion of steam from boiler pressure to exhaust pressure is carried out in a # of steps 2. each stage has a set of nozzles and row of blades 3. all velocity available is developed in 1 set of nozzles 4. rows of moving blades are separated by partitions or diaphragms with nozzles |
2, 4 |
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In a/an _____ turbine there is a difference in pressure across the _____ blades. Therefore the steam will tend to _____ around the periphery of the blades instead of passing through them. 1. impulse 2. moving 3. reaction 4. drip 5. stationary 6. leak |
3, 2, 6 |
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The pressure at the outlet from the moving blades is the same as the pressure at the inlet to the moving blades in a turbine a) topping b) reaction c) back pressure d) impulse e) extraction |
d) impulse |
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When disc rotors are assembled, the discs are heated until they are easily slid along the shaft and then located in the correct position on the shaft and shaft key. A small clearance prevents a) noise b) slippage c) thermal stress in the shaft d) acceleration |
c) thermal stress in the shaft |
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In an impulse steam turbine nozzle the following events take place 1. steam pressure decreases 2. enthalpy of the steam decreases 3. velocity of the steam increases 4. volume of the steam increases |
1, 2, 3, 4 |
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In a/an _____ turbine there is a difference in pressure across the _____ blades. Therefore the steam will tend to _____ around the periphery of the blades instead of passing through them. a) extraction b) velocity compounded c) pressure compounded d) pressure velocity compounded e) mixed pressure |
d) pressure velocity compounded |
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In a back pressure turbine the process steam pressure is a) kept constant and generator output depends on the demand for steam b) varied and the generator output remains constant c) kept constant and generator output remains constant d) not important |
a) kept constant and generator output depends on the demand for steam |
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Extraction turbines are turbines where steam is extracted at one or more points at constant a) flow b) pressure c) load d) temperature |
b) pressure |
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____turbines are large turbines with parallel shafts with a generator on each shaft a) condensing b) tandem-compounding c) extraction bleeder d) condensing bleeder e) cross compound |
e) cross compound |
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Steam turbine stationary nozzles create a 1) decrease in steam pressure 2) increase in steam enthalpy 3) increase in steam coefficient of friction 4. increase in steam velocity |
1, 4 |
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Steam turbine casing joints are made steam tight by matching ___exactly a) thin high temperature gaskets b) bowel pins c) alignment notches d) flange faces |
d) flange faces |
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The purpose of the bucket or moving blade on the rotor is to convert the _____energy of the steam into ____ energy. a) heat, potential b) kinetic, useful c) kinetic, mechanical d) heat, kinetic |
c) kinetic, mechanical |
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Reaction steam turbines often use____ seals as part of the shroud with the seal clearances kept as small as possiblie a) radial b) water c) radial and axial d) carbon |
c) radial and axial |
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Reaction turbine blades (moving) 1. convert the kinetic energy of the steam into mechanical energy 2. convert heat energy into kinetic energy 3. are nozzle shaped 4. increase the absolute velocity |
1, 2, 3 |
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During start up of a steam turbine the thrust block is pushed against a stop in the direction of the exhaust for a) maximum seal clearance b) minimum seal clearance c) maximum blade efficiency d) maximum blade clearance |
d) maximum blade clearance |
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It is general practice to let the thickness of the walls and flanges _____ from inlet to exhaust end of a steam turbine casing a) decrease b) fluctuate c) be the same d) vary |
a) decrease |
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A condensing turbine water seal is used ____ to insure that no air leaks in along the shaft a) on start-up b) at speed below 2000 rev/min c) on shut-down d) only on condensing turbine e) at speeds above 2000 rev/min |
e) at speeds above 2000 rev/min |
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A steam turbine assembled casing is machined off inside in a boring mill to 1. make grooves for shaft seals 2. make grooves for diaphragms 3. machine surfaces for bearings 4. machine flange surfaces flat |
1, 2, 3 |
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In a steam turbine using velocity compounding the velocity is absorbed in a) two or more rows of moving blades b) one set of nozzles c) two or more rows of stationary blades d) two sets of nozzles |
a) two or more rows of moving blades |
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a) 1% b) 15% c) 20 % d) 10% |
c) 20% |
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A back pressure turbine with exhaust steam going to an old boiler header that is supplying steam to an old lower pressure turbine is called a) condensing bleeder turbine b) cross compounding turbine c) condensing turbine d) topping turbine |
d) topping turbine |
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On an extraction turbine the extraction pressure is a) not critical b) varied according to turbine load c) maintained constant regardless of turbine load d) proportional to the turbine load e) reduced if load increases |
c) maintained constant regardless of turbine load |
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Proper expansion of steam through a turbine nozzle depends on what? 1. operation at the design pressure 2. operation at the design rotational speed 3. operation at the design temperature 4. selection of the proper nozzle material |
1, 3 |
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_____turbines are large turbines consisting of two or more turbines in series coupled together as one shaft and applied to one generator a) topping b) tandem-compounding c) condensor bleeder d) cross compound |
b) tandem-compounding |
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Carbon rings, when used for turbine shaft seal require a) lubrication b) constant supervision c) no lubrication d) monthly replacement |
c) no lubrication |
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Typical applications for turbines could be 1. feedwater pumps 2. blowers 3. chemical feed pumps 4. electrical generation |
1, 2, 4 |
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A hollow drum rotor, for good balance, is machined both outside and inside thus the drum must be open at one end. How is the drum end cover with shaft installed in the rotor? a) press fitted b) welded on c) bolted d) press fitted and welded e) shrink fitted and welded |
e) shrink fitted and welded |
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The purpose of a thrust bearing on a large reaction steam turbine is to 1. give confidence to the operator 2. keep the rotor in an exact position in the casing 3. prevent any steam from escaping 4. absorb any axial thrust on the rotor 5. support the dummy piston |
2, 4 |
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In a reaction turbine 1. velocity increases in the moving blades 2. velocity decreases in the stationary blades 3. pressure drops in the moving blades 4. pressure drops in the stationary blades |
3, 4 |
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Reaction turbine has a) rows of stationary nozzles and moving blades b) rows of stationary blades alternating with rows of moving blades c) a force on the blades produced according to Newton's 2nd law of motion d) a pressure increases in the nozzles e) velocity drop in the stationary blades |
b) rows of stationary blades with alternating rows of moving blades |
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Disc rotors 1. may be made from a solid forging 2. may be made up of separate discs and a shaft 3. have discs that are shrunk onto the shaft 4. Have discs whose bore is 0.1% smaller than the shaft |
1, 2 |
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In an impulse turbine the enthalpy of the steam as it passes through the stationary nozzles a) stays the same b) increases c) fluctuates d) dissapears e) decreases |
e) decreaeses |
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When the exit pressure of a steam turbine nozzle is less than____times the inlet pressure then a _____nozzle will be used a) 0.757, convergent b) 0.577, convergent-divergent c) 0.757, convergent-divergent d) 0.757, convergent |
b) 0.577, convergent-divergent |
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A reaction turbine results in a long machine due to a larger number of alternate rows of a) nozzles and moving blades b) nozzles and stationary blades c) fixed and moving blades d) stationary blades |
c) fixed and moving blades |
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In a steam turbine using velocity compounding____expand the steam from initial to exhaust pressure a) two sets of nozzles and moving blades b) stationary blades c) stationary and moving blades d) moving blades e) one set of nozzles |
e) one set of nozzles |
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The distinguishing feature of a reaection turbine is the fact that the pressure drop across the _____blades a) cutting b) moving c) sectional d) stationary e) angular |
b) moving |
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Which of newton's laws applies to a force being applied to an impulse turbine blade? a) 1st b) 2nd c) 3rd d) 4th |
b) 2nd |
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In a reaction turbine the steam pressure drops across both the fixed and moving blades while the steam's _____rises in the fixed blades and drops in the moving blades. a) pressure b) temperature c) flow d) level e) velocity |
e) velocity |
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Disc rotors made from a solid forging are 1. more efficient than built-up rotors 2. fully balanced 3. expensive 4. strong |
2, 3, 4 |
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In an impulse turbine as the steam, passes through the moving blades the ____drops but the ____remains the same a) velocity, pressure b) enthalpy, velocity c) pressure, velocity d) volume, velocity |
a) velocity, pressure |
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The entrance angle of a reaction blade is a) parallel to the rotational direction b) low as to reduce frictional losses c) almost 90 degrees d) is the same as the exit angle |
c) almost 90 degrees |
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A topping turbine is a special application of a ______turbine a) condensing b) extraction c) condensing-bleeder d) tandem compound e) back pressure |
e) back pressure |
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The purpose of compounding in a steam turbine is to a) create pressure b) reduce steam and blade velocity c) create higher rotational speeds d) allow use of higher steam pressures |
b) reduce steam and blade velocity |
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When turbine blade velocity is equal to one half the steam velocity, then exiting steam a) frictional losses are maximized b) allows a smaller turbine to be used c) permits higher steam pressure use d) absolute velocity equals zero |
b) allows a smaller turbine to be used |
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When steam leaves the moving blades at zero absolute velocity a) fricitonal losses are maximized b) a smaller turbine to be used c) higher steam pressure use d) turbine blade velocity equals one half the steam velocity |
d) turbine blade velocity equals one half the steam velocity |
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On larger turbines the ____ is split in a horizontal direction a) shaft b) governor c) cylinder d) rotor e) drum |
c) cylinder |
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Convergent-divergent nozzles are used when a) high rotational speeds are required b) low rotational speeds are required c) low pressure drops are required d) high preessure drops are required |
d) high pressure drops are required |
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In an impulse turbine, the nozzles a) are formed by airfoil shaped blades b) are found in the first stage c) are mounted in diaphragms d) cause a decrease in velocity e) are located in the rotor |
c) are mounted in diaphragms |
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A thrust adjusting gear a) is found on impulse turbines b) adjust the thrust generated by the turbine c) positions the turbine rotor axially d) compensates for steam pressure variations |
c) positions the turbine rotor axially |
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In a condensing - bleeder turbine up to 2% of the total steam flow may be bled off. What is the bleed-steam used for? a) building heating b) relieving pressure c) atomization of the fuel d) to be reheated in the boiler e) feed-water heating |
e) feed-water heating |
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A generator coupled to one shaft to a turbine consisting of two or more turbine in series is called a a) condensing bleeder b) cross compound turbine c) mixed pressure d) tandem compound turbine |
d) tandem compound turbine |
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A dummy piston on a steam turbine is used to a) counter vibration and ensure a smooth running unit b) increase turbine output c) measure axial positions d) counter end thrust |
d) counter end thrust |
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In a steam turbine having pressure drop acrtoss the moving blades, an unbalanced ____ thrust will be developed upon the rotor a) axial b) centrifugal c) radial d) impulse |
a) axial |
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A steam turbine has a high capacity to _____ratio a) velocity b) rotational speed c) steam temperature d) volume e) weight |
e) weight |
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A pressure-velocity compounded turbine may have 1. 2 velocity compounded stages 2. 1 velocity compounded stages 3. sevaral pressure compounded stages 4. pressure and velocity compounded stages |
1, 2, 3, 4` |
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Couplings 1. transmit power from one shaft to another 2. depend on the shear force of the bolts to transmit the power 3. compensate for axial expansion and contraction of the rotor 4. are an integral part of the shaft on larger turbines |
1, 2, 3, 4 |
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Advantages of a steam turbine include 1. high rotational speed 2. low rub speed 3. high efficiency 4. low size to output capacity 5. can be reversible |
1, 3, 4 |
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A steam turbine balance piston is fitted with _____to ensure a tight seal a) carbon ring seals b) blade seals c) water seals d) diaphragms e) labyrinth seals |
e) labyrinth seals |
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Where would you expect to find a turbine that can be reversed a) pulp mill b) gas plant c) amusement park d) petroleum process plant e) ships |
e) ships |
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In a reaction turbine the steam pressure drops across both the fixed and moving blades while the steam's ____ velocity rises in the fixed blades and drops in the moving blades a) secondary b) primary c) stationary d) moving e) absolute |
e) absolute |
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Of all the heat engines and prime movers the steam turbine is considered to be a) nearest to the ideal b) least efficient c) too expensive to maintain d) too slow in rotational speed |
a) nearest the ideal |
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The steam turbine is an ideal prime mover because 1. of its ability to use high pressure and high temperature steam 2. it is quiet in operation 3. of its high capacity to weight ratio 4. of its high efficiency 5. it is reversible |
1, 3, 4 |
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Rotors for high ouputs and high temperatures are generally made of ____ steels a) chromium b) chromium nickel c) nickel molybdenum d) chromium nickel molybdenum |
d) chromium nickel molybdenum |
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The disadvantages of a steam turbine include 1. cannot be made reversible 2. efficiency is poor 3. no internal lubrication 4. low rotational speed 5. high capacity to weight |
1, 2, 4 |
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Steam turbine stationary nozzles serve to 1. decrease steam pressure 2. increase steam enthalpy 3. increase steam friction 4. increase steam velocity |
1, 4 |
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Materials at the given maximum temperature and under constant pressure continue to deform with very slowly increasing strain of the material, this is called a) creep b) elongation c) deformation d) jerking |
a) creep |
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Throttling of steam through a valve is an a) isobaric proccess b) isothermal process c) polytropic process d) isenthalpic process |
d) isenthalpic process |
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With a condensing turbine the ______heat in the exhaust steam is transferred to the cooling water a) residual b) latent c) leftover d) superheated |
b) latent |
