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power prep Steam turbine Auxiliaries and Operation quiz

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power engineering 3b2 Quiz on power prep Steam turbine Auxiliaries and Operation quiz, created by TRAVIS CANNING on 27/02/2016.
TRAVIS CANNING
Quiz by TRAVIS CANNING, updated more than 1 year ago
TRAVIS CANNING
Created by TRAVIS CANNING over 8 years ago
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Resource summary

Question 1

Question
In a large steam turbine lubricating oil system the function of the oil is to lubricate and ___________ the bearings.
Answer
  • keep dirt out of
  • polish
  • cool
  • keep moisture away from
  • support

Question 2

Question
what type of instrumentation ins installed on the discharge side of an oil lubricated bearing
Answer
  • oil filter
  • moisture separator
  • dewpoint monitor
  • flow measuring device
  • thermometer

Question 3

Question
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
Answer
  • bowing
  • hogging
  • sagging
  • warping
  • bending

Question 4

Question
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:
Answer
  • bowing
  • hogging
  • sagging
  • warping
  • bending

Question 5

Question
when a steam turbine is shut down it should be put on barring gear for a minimum of:
Answer
  • 3 hours
  • 24 hours
  • 72 hours
  • as determined by the plant manager
  • barring should never be shut off

Question 6

Question
Barring gear shaft rotation is typically:
Answer
  • 1-3 rpm
  • 5-10 rpm
  • 20-40 rpm
  • 60 rpm
  • 3600 rpm

Question 7

Question
while large steam turbine is on barring gear what other system should be placed in service
Answer
  • lube oil coolers
  • lube oil filtering
  • hydrogen sealing
  • stator water
  • jacking oil

Question 8

Question
which of the following is not a type of steam turbine governing:
Answer
  • Nozzle
  • Throttle
  • Overload
  • Bypass
  • Impulse

Question 9

Question
Nozzle governing is utilized on __________ turbines
Answer
  • impulse
  • reaction
  • condensing
  • extraction
  • impulse or reaction turbines

Question 10

Question
Nozzle governing
Answer
  • opens a nozzle from 0 % to 100 % as the load is increased on a turbine
  • opens a series of nozzles in succession as the load is increased
  • utilizes flyball weights to control a steam valve
  • is used on the later stages of an impulse turbine to control speed
  • none of the above

Question 11

Question
Impulse steam turbine speed can be controlled by throttling the steam supply through a control valve and:
Answer
  • varying the firing rate on the boiler
  • increasing the load on the generator
  • increasing the superheat to the steam
  • opening or closing a series of nozzles
  • bypassing the low pressure turbine through extraction

Question 12

Question
Bypass governing allows
Answer
  • an increase in load but a decreased efficiency
  • an increase in load with a increase in efficiency
  • a decrease in load with a decrease in efficiency
  • a decrease in load with an increase in efficiency
  • increase load with no change in efficiency

Question 13

Question
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.
Answer
  • lag
  • droop
  • variance
  • offset
  • drag

Question 14

Question
In a simple flyweight governor:
Answer
  • speed is controlled by varying the number of weights in the governor
  • speed is controlled by restricting the inward movement
  • the weights move inward with an increase in speed
  • increasing spring tension increases the controlled spring
  • all of the above

Question 15

Question
When a steam turbine exceeds its speed setpoint
Answer
  • boiler pressure is reduced to limit the steam speed
  • the flyball weights will move outward which will in turn operate an oil relay which will close off the steam valve
  • the turbine will likely catastrophically fail
  • the barring gear will engage and act as a clutch to reduce the speed
  • a braking system is employed until within limits

Question 16

Question
Turbine lubricating oil
Answer
  • Is not required for small impulse turbines
  • must be changed every four months
  • lubricates the blades
  • can be used to operate the turbine governor
  • should be preheated before use

Question 17

Question
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
Answer
  • 2,4,5
  • 2,3,4,5
  • 1,2,4
  • 3,4,5
  • 4,5

Question 18

Question
The overspeed trip of a steam turbine
Answer
  • operates on turbine vibrations due to high speed
  • is installed on all turbines
  • can be adjusted according to the load demand
  • is regulated by exhaust pressure
  • sheds the load in the event of high pressure

Question 19

Question
Turbine overspeed trip
Answer
  • prevents the turbine from vibrating
  • will close the steam stop valve to the turbine
  • is operated by a spring loaded pin in the rotating blades
  • supplies the operator with rpm indications
  • reduces the turbine speed by increasing the back pressure

Question 20

Question
The great majority of steam turbine governing systems utilize
Answer
  • hydraulic system principle
  • pneumatic system principle
  • mechanical centrifugal principle
  • lever principle
  • bimetal expansion principle

Question 21

Question
when starting a steam turbine it is customary practice to:
Answer
  • analyze the oil for water prior to rolling
  • turn on all cooling water systems first
  • place the speed control system in service once the unit is rolling
  • test the overspeed trip as soon as running speed is attained
  • stop the auxiliary oil pump as soon as steam begins to turn the unit

Question 22

Question
which of the following mechanisms would not be sued on an emergency overspeed trip device?
Answer
  • pneumatic
  • electrical
  • hydraulic
  • mechanical
  • any of the above may be used

Question 23

Question
when starting up a cold steam turbine, what position should the main steam valve intitially be opened to?
Answer
  • 10 % or less
  • 25 %
  • 50 %
  • 75 %
  • 100 %

Question 24

Question
when is the barring gear engaged on a large turbine during a shutdown
Answer
  • when the main steam stop valve is closed
  • at 50 % operating speed
  • when the turbine is rotating at 3rpm or less
  • upon opening the generator breaker
  • when the turbine has come to a complete stop

Question 25

Question
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?
Answer
  • shut off the boiler feed pump
  • drain the boiler
  • open the turbine drains
  • put your feet up and have an extended coffee break
  • hang the boiler lock-out tags

Question 26

Question
During the operation of a large steam turbine:
Answer
  • the main auxiliary oil pump supplies oil to the journal bearings
  • the main auxiliary oil pump is driven by the turbine shaft
  • if the main oil pump fails the jacking oil pump may take over
  • the emergency overspeed trip receives the same oil pressure as the journal bearings
  • only answers A) and B) from above

Question 27

Question
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
Answer
  • 1,2,3,4,5
  • 1,4,5
  • 2,4
  • 1,3,5
  • none of the above

Question 28

Question
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
Answer
  • 1,2,3,4
  • 2,3,4,5
  • 1,3,4,5
  • 1,2,4,5
  • all of the above

Question 29

Question
The internal spring loaded tripping bold has a center of gravity:
Answer
  • at midpoint
  • towards the head end of the bold
  • towards the nut end of the bolt
  • concentric
  • perpendicular with the shaft

Question 30

Question
The overspeed trip on a steam turbine is typically set to operate at ______________ % overspeed
Answer
  • 5%
  • 10%
  • 20%
  • 25%
  • 50%

Question 31

Question
The purpose of a condenser is to:
Answer
  • extract heat from the condensate to be returned back to the cooling pond
  • subcool the condensate below the saturation temperature
  • convert the steam to water after the steam has expanded through the turbine
  • remove the non-condensables from the steam
  • improve the boiler overall efficiency

Question 32

Question
The addition of a condenser to a steam turbine vs a turbine exhausting to atmosphere may increase the overall efficiency of the turbine by:
Answer
  • 10%
  • 25%
  • 50%
  • 75%
  • 100%

Question 33

Question
A surface condenser: (pick the incorrect answer)
Answer
  • acts as a dearator
  • converts steam to condensate
  • helps maintain vacuum at the turbine exhaust
  • cools the condensate below the saturation temperature
  • may be cylindrical, oval or rectangular in shape
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