4670812
Descripción
Test por TRAVIS CANNING, actualizado hace más de 1 año
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Creado por TRAVIS CANNING
hace más de 8 años
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Pregunta 1
Pregunta
In a large steam turbine lubricating oil system the function of the oil is to lubricate and ___________ the bearings.
Respuesta
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keep dirt out of
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polish
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cool
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keep moisture away from
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support
Pregunta 2
Pregunta
what type of instrumentation ins installed on the discharge side of an oil lubricated bearing
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oil filter
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moisture separator
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dewpoint monitor
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flow measuring device
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thermometer
Pregunta 3
Pregunta
When a turbine is left cold and at a standstill, the weight of the rotor will tend to cause the rotor to sag slightly, this is also referred to as
Respuesta
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bowing
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hogging
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sagging
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warping
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bending
Pregunta 4
Pregunta
when a hot turbine rotor has cooled at a standstill, the lower half will cool faster than the upper half. This may cause the rotor to bend upwards which may also be referred to as:
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bowing
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hogging
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sagging
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warping
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bending
Pregunta 5
Pregunta
when a steam turbine is shut down it should be put on barring gear for a minimum of:
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3 hours
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24 hours
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72 hours
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as determined by the plant manager
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barring should never be shut off
Pregunta 6
Pregunta
Barring gear shaft rotation is typically:
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1-3 rpm
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5-10 rpm
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20-40 rpm
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60 rpm
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3600 rpm
Pregunta 7
Pregunta
while large steam turbine is on barring gear what other system should be placed in service
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lube oil coolers
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lube oil filtering
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hydrogen sealing
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stator water
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jacking oil
Pregunta 8
Pregunta
which of the following is not a type of steam turbine governing:
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Nozzle
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Throttle
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Overload
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Bypass
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Impulse
Pregunta 9
Pregunta
Nozzle governing is utilized on __________ turbines
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impulse
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reaction
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condensing
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extraction
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impulse or reaction turbines
Pregunta 10
Pregunta
Nozzle governing
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opens a nozzle from 0 % to 100 % as the load is increased on a turbine
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opens a series of nozzles in succession as the load is increased
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utilizes flyball weights to control a steam valve
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is used on the later stages of an impulse turbine to control speed
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none of the above
Pregunta 11
Pregunta
Impulse steam turbine speed can be controlled by throttling the steam supply through a control valve and:
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varying the firing rate on the boiler
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increasing the load on the generator
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increasing the superheat to the steam
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opening or closing a series of nozzles
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bypassing the low pressure turbine through extraction
Pregunta 12
Pregunta
Bypass governing allows
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an increase in load but a decreased efficiency
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an increase in load with a increase in efficiency
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a decrease in load with a decrease in efficiency
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a decrease in load with an increase in efficiency
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increase load with no change in efficiency
Pregunta 13
Pregunta
The difference between the no-load and full-load speed, expressed as a percentage of the set speed, is called the ______ of the governor. As the load increases, the speed will ________ below the set speed.
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lag
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droop
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variance
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offset
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drag
Pregunta 14
Pregunta
In a simple flyweight governor:
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speed is controlled by varying the number of weights in the governor
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speed is controlled by restricting the inward movement
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the weights move inward with an increase in speed
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increasing spring tension increases the controlled spring
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all of the above
Pregunta 15
Pregunta
When a steam turbine exceeds its speed setpoint
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boiler pressure is reduced to limit the steam speed
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the flyball weights will move outward which will in turn operate an oil relay which will close off the steam valve
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the turbine will likely catastrophically fail
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the barring gear will engage and act as a clutch to reduce the speed
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a braking system is employed until within limits
Pregunta 16
Pregunta
Turbine lubricating oil
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Is not required for small impulse turbines
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must be changed every four months
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lubricates the blades
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can be used to operate the turbine governor
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should be preheated before use
Pregunta 17
Pregunta
The turbine overspeed trip:
1. prevents the turbine from vibrating
2. prevents the turbine exceeding the maximum rated speed
3. is operated by a spring loaded pin in the rotating blades
4. will close the steam stop valve
5. should be tested before the turbine is placed in service
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2,4,5
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2,3,4,5
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1,2,4
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3,4,5
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4,5
Pregunta 18
Pregunta
The overspeed trip of a steam turbine
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operates on turbine vibrations due to high speed
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is installed on all turbines
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can be adjusted according to the load demand
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is regulated by exhaust pressure
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sheds the load in the event of high pressure
Pregunta 19
Pregunta
Turbine overspeed trip
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prevents the turbine from vibrating
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will close the steam stop valve to the turbine
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is operated by a spring loaded pin in the rotating blades
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supplies the operator with rpm indications
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reduces the turbine speed by increasing the back pressure
Pregunta 20
Pregunta
The great majority of steam turbine governing systems utilize
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hydraulic system principle
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pneumatic system principle
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mechanical centrifugal principle
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lever principle
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bimetal expansion principle
Pregunta 21
Pregunta
when starting a steam turbine it is customary practice to:
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analyze the oil for water prior to rolling
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turn on all cooling water systems first
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place the speed control system in service once the unit is rolling
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test the overspeed trip as soon as running speed is attained
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stop the auxiliary oil pump as soon as steam begins to turn the unit
Pregunta 22
Pregunta
which of the following mechanisms would not be sued on an emergency overspeed trip device?
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pneumatic
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electrical
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hydraulic
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mechanical
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any of the above may be used
Pregunta 23
Pregunta
when starting up a cold steam turbine, what position should the main steam valve intitially be opened to?
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10 % or less
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25 %
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50 %
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75 %
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100 %
Pregunta 24
Pregunta
when is the barring gear engaged on a large turbine during a shutdown
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when the main steam stop valve is closed
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at 50 % operating speed
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when the turbine is rotating at 3rpm or less
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upon opening the generator breaker
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when the turbine has come to a complete stop
Pregunta 25
Pregunta
On shutting down a large steam turbine what is one of the first steps that an operator should do once the main steam valve is closed?
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shut off the boiler feed pump
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drain the boiler
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open the turbine drains
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put your feet up and have an extended coffee break
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hang the boiler lock-out tags
Pregunta 26
Pregunta
During the operation of a large steam turbine:
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the main auxiliary oil pump supplies oil to the journal bearings
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the main auxiliary oil pump is driven by the turbine shaft
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if the main oil pump fails the jacking oil pump may take over
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the emergency overspeed trip receives the same oil pressure as the journal bearings
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only answers A) and B) from above
Pregunta 27
Pregunta
When a turbine hydraulic overspeed trip is activated
1. a spring closes the main steam valve
2. oil pressure quickly closes the main steam valve
3. the oil pilot drain closes
4. oil pressure to the valve is shut off
5. the stop valve oil cylinder drain is opened
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1,2,3,4,5
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1,4,5
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2,4
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1,3,5
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none of the above
Pregunta 28
Pregunta
Which of the following parameters are monitored and recorded during the operation on a steam turbine.
1. main steam pressure
2. main steam temperature
3. oil pressure and temperature
4. condenser vacuum
5. hotwell pressure and temperature
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1,2,3,4
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2,3,4,5
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1,3,4,5
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1,2,4,5
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all of the above
Pregunta 29
Pregunta
The internal spring loaded tripping bold has a center of gravity:
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at midpoint
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towards the head end of the bold
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towards the nut end of the bolt
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concentric
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perpendicular with the shaft
Pregunta 30
Pregunta
The overspeed trip on a steam turbine is typically set to operate at ______________ % overspeed
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5%
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10%
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20%
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25%
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50%
Pregunta 31
Pregunta
The purpose of a condenser is to:
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extract heat from the condensate to be returned back to the cooling pond
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subcool the condensate below the saturation temperature
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convert the steam to water after the steam has expanded through the turbine
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remove the non-condensables from the steam
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improve the boiler overall efficiency
Pregunta 32
Pregunta
The addition of a condenser to a steam turbine vs a turbine exhausting to atmosphere may increase the overall efficiency of the turbine by:
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10%
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25%
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50%
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75%
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100%
Pregunta 33
Pregunta
A surface condenser: (pick the incorrect answer)
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acts as a dearator
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converts steam to condensate
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helps maintain vacuum at the turbine exhaust
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cools the condensate below the saturation temperature
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may be cylindrical, oval or rectangular in shape
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