Turbine, governors and heat exchanger test Flashcards
when working around steam turbines, you must be aware of steam leaks because they
are invisible
can burn you
are dangerous
all the above
All of the above
turbines are equipped with an emergency trip mechanism in the event of a/an
under speed
over speed
overlaod
shut down
Over speed
Newtons’ 3rd law states the for every action there is a/an
equal and same reaction
an equal and opposite reaction
change in volume
pressure drop when there is a speed drop
An equal and opposite reaction
impulse blades harness the steam energy by
change in pressure
change in direction
change in volume
all the above
Change in Direction
when you have no pressure drop across the impulse blading (because of their symmetrical design), there will be no need for sealing on either side of the rotating blades
true
False
True
reaction blades
are the same distance apart all the way thru the blading
create a pressure drop
cause the steam to accelerate
both the 2nd and 3rd answers are correct
Both second and third answers are correct
reaction turbines may have a velocity compounded impulse section at the inlet of the turbine to help make the turbine machine shorter and eliminate the need for sealing at the high pressure end
true
false
True
extraction turbines remove steam from the casing which is used for another plant process
true
false
True
condensing turbines use a condenser to increase the turbines efficiency by creating a high pressure back pressure at the outlet of the turbine
true
False
False
Reduces the backpressure
many large turbines have bearings with spherical seats which allows the bearing to tilt according to the sag in the turbine shaft
true
False
True
the thrust bearing is usually locate in the
steam outlet end
steam inlet end
before the inlet bearing
after the outlet bearing
Steam inlet end
carbon seals are used on small turbines and their match marks are installed facing the pressure
true
False
True
when thermal growth exceeds the capacity of the labyrinth seals you would use a
carbon seal
tilting pad seal
higher spring pressure
annulus seals
Annulus Seal
moment weight is the weight of the blade
plus the radial distance to the center of gravity of each blade
times the shaft diameter of the rotor
times the radial distance to the center of gravity of each blade
the speed of the blade as it rotates around the axis of the housing
times the radial distance to the center of gravity of each blade
coupling bolts are marked for each specific location due to
fit
balance
none of the above
both the 1st and 2nd answers are correct
Both first and third answers are correct
speed control of turbines is usually controlled by governors under varying load conditions
true
False
True
over-speed trips use centrifugal forces that overcome the spring tension and hit the over-speed trip mechanism. these trips must be manually reset
true
False
True
the main stop valve shuts off the steam to the turbine
true
False
True
the steam turbine chest has a witches hat that keeps particles from entering the turbine
true
False
True
the steam supply to smaller impulse turbines should be free of moiture and super heated
true
False
True
steam admission valves can be moved or lifted by a cam lift or bar lift that overcomes spring pressure to open
true
False
True
thrust controls for a turbines axial movement can be
balance piston
dummy piston
dual flow rotors
all the above
All of the above
a turning gear or barring gear is used on large turbines to rotate the turbine rotor(s) from 1 to 60 rpm. this slow turning allows the sag or bow in the rotor to be removed
true
False
True
jacking oil is used to lift the shaft off of the bearing surfaces until the rotor gets up to __________rpm. then the main lubrication system will take over and the jacking oil shut off.
10-20
50-60
100-200
500-600
50-60 rpm
debris buildup or deposits on turbine blades and nozzles can be removed by using
walnut shells
rice
temperture changes after shutting down the turbine
high pressure dry ice
all the above
All of the above
removal of flange nuts in most turbines is accomplished by using
hydraulic stretch of the bolt
heating the bolt internally
torque mulitipliers
all the above
All of the above
when lifting of turbine covers, it is important to install the guide pins so the cover can be lifted off level and straight up, eliminating any potential for damage
true
false
True
bearing height and position for turbines is adjusted in the pedastal by the addition or subtraction of shims under the bearing seat pads
true
Option 2
True
the typical babbitted bearing clearance is about ______ per 1” of shaft diameter
0.001”
0.003”
0.005”
0.010”
.001”
oil voscosity for bearings in a turbine is maintained by running them in oil between 0 and 120 degrees C
true
false
False
when controlling thrust in a steam turbine, you usually only need 1 location for the thrust bearing so the rotor is free to expand in either direction from it
true
False
True
for properly installed diaphragms, you would need to do which of the following
use shims
use crush pins
the halves installed with a slight protrusion
all the above
All if the above
when using lead wire to check labyrinth seals clearance, you would use a blade micrometer because it can read into the profie left when squished
true
false
True
before installing the blades on the rotor, you need to make sure to check the blades for correct location by checking the match marks or numbers
true
false
True
once the bolts are tightened on the flanges for the turbine casing, they can be checked for tightness with ultrasonic testing. (high frequency sound waves)
true
False
True
which of the following would give you a false reading on bolt stretch (bolts below the required torque)
lubrication of the threads
heating the stud
heating the flange
tightening the stud to the specified torque
Heating the flange
when doing a coupling alignment on a turbine, you will make movement between the _____ and the _______.
foundation, turbine feet
sole plate, base plate
sole plate, turbine feet
base plate, foundation
Sole plate and turbine feet
piping for the turbine must
be able to handle the ssteam flow
not put strain on the casings
allow for expansion
all the above
All of the above
turbines are set on the bed of the foundation on
sole plates
grout pads
wedge blocks
all the above
All of the above
when initial parts are installed for the turbine (bottom halves of the turbine cylinders), they are installed with lubricated keyways that
lock the turbine solidly in place
allow for rotor sag
allow the turbine to expand in all temperature conditions
none of the above
Allow the turbine to expand in all temperature conditions
when installing the bearing pedestals and turbine cylinders, you need to add the tops of the cylinders and pedestals so the weight resembles the turbines whole weight and helps take the sag out of the cylinders
true
False
True
a benchmark is the baseline from where all elevations involved in the turbine installation, will be taken from
true
false
True
when installing bearings, you use a bridge gauge to check bearing wear (helps with the maintenace schedualing) or bearing clearance
true
false
True
during startup, steam is admitted to the turbine to rotate it on its own power________
after the jacking oil has lifted the rotor
after several hours and when the rotor is straight and up to the proper speed
after a few days and and the rotor is striaight and jacking oil still on
once the baring gear has it up to 50 to 60 rpm
After several hours wnd when the rotor is straight and up to proper speed
once the steam is first admitted, you should make sure the drain lines are plugged until thermal saturation is reached and that the turbine runs thru any critical speeds as fast as possible
true
False
False
Make sure drain lines are all open until just steam comes out
the gas turbine is an internal combustion engine that coverts fuel to useable power
true
False
True
the efficiency of a gas turbine depends on the temperature the air can be raised and the use of cold dense air that will create a marked increase in gas turbine output
true
False
True
regeneration is when some of the exhaust air from the gas turbine is used in the process to generate steam power
true
False
False
Exhaust gas is regenerated to assist in the heating of the gasses before the turbine
the gas turbine shaft type that has one shaft running inside the other is
single shaft
split shaft
twin spool shaft
direct coupled
Twin spool shaft
in the gas generation section, the main parts are the compressor and combustion chamber
true
False
True
the power section of a gas turbine harnesses energy from the cold gasses as efficiently as possible
true
False
False
Harnesses hot expanding gases
in the split shaft turbine design, the gas generation turbine is connected to the compressor and the power turbine is connected to the load.
true
False
True
the gas turbine cycle that uses a heat exchanger or regenerators to make it more efficient is
open cycle
semi-closed cycle
closed cycle
all the above
Semi Closed cycle
in the regeneration cycle, the turbine uses exhaust heat to assist in heating and expansion of the gases after the compressor but before the combustion chamber
true
False
True
one of the greatest advantages of the gas turbine is its power to weight ratio
true
False
True
one of the major disadvantages of the gas turbine is its low thermal efficiency
true
false
one of the major disadvantages of the gas turbine is its low thermal efficiency
true
false
in the gas turbine, the compressor increases the air pressure and air temperature until it hits the diffuser. here the air velocity is slowed down and the air pressure decreased
true
False
False
Lowers the velocity and increase the pressure
the air pressure during ignition is always higher than in the diffuser when travelling thru the turbine.
true
false
False
Diffuser has the highest pressure
the turbine is attached to the compressor by a shaft running thru the turbine engine and about ____ of the power developed by the gas turbine is used to drive the compressor and accessories
25%
50%
75%
10%
75%
if gases back up into the compressor, it will lead to a condition of compressor surge or stall
true
false
True
air filtration for stationary gas turbines can use spiral vane seperators and V-bag filters
true
false
True
pulse type filters are used to reduce icing and hoarfrost build-up
true
false
True
to improve air flow at the intake, you would use
dense filtering
sharp bends in piping
guide vanes
none of the above
Guide Vanes
in the combustion chamber housing, the ingniter is in the
primary zone
intermediate zone
dilution zone
fuel nozzle zone
Primary Zone
primary air is used for mixing with the fuel
true
False
True
the secondary air is used to control the temperature and also help in the combustion process
true
false
false
Only control the temperature by moving air around the outside of the liner
the transition piece makes sure that all hot gases are mixed with air so there is no hot gas pockets
true
False
True
when using can type combustion chambers, every chamber will need its own igniter
true
False
True
the fuel nozzle or injector is used to spray the fuel in a fine mist or vapourize the the fuel
true
False
True
the turbine assembly harnesses the power of the hot expanding gases and has blades and nozzles made of mild steel
true
False
False
Made of high strength steel
you can increase the endurance of the nozzles, by adding new alloys such as ceramic or use air cooled nozzle vanes
true
false
True
the rotor blades on the rotor discs can have clearance when mounted, so that they can allow for thermal expansion
true
False
True
labyrinth seals are used on both compressor and turbine and can have help for sealing from sealing jets of air routed from the compressor section
true
false
True
a starting motor is an essential auxiliary component that needs to route the turbine to about _____% of its maximum speed
10
20-30
40-50
60-70
20-30%
power loss in a gas turbine can be caused by dirt deposits on the compressor blades
true
False
True
to check for interference and rubbing between air seals and blades, you would need to manually turn the engine over slowly
true
False
True
when replacing blades on a turbine with new blade, you must make sure
the blade has the same moment weight.
the blade has the same type of mount.
you use proper installation procedures set out by the manufacture.
all the above
All of the above
when doing an engine wash, you would do it only when using the starting mechanism, not while it is running
true
false
False
About once a month a cleaning solution is sprayed into compressor blades while it is running
in regards to the inlet or intake system on a gas turbine, a 1 % loss in intake pressure results to about ______ % loss in engine power
1
2.5
5
10
2.5
insulation (thermal) can be used on turbines to help with personal protection, noise reduction and operational efficiency of the turbine
true
False
True
after replacing a governor with a new one, the millwright needs to fill the governors reservoir with the correct oil and adjust the speed at start up
true
False
True
a governor will automatically control the speed of a prime mover under varying load and can also
maintain the selected speed
limit the slow and fast speed
shut down the prime mover if it over speeds
all the above
All of the above
all automatic governor control systems have 3 main components
detection, transmission, maintenance
detection, ignition, correction
detection, transmission, correction
transmission, correction, maintenace
Detection, transmission, correction
in spark ignition, the governor actuates a throttle valve in the intake passage between the carburetor and manifold. the governor operates off the engine vacuum to move the throttle valve
true
False
True
the mechanical governor can use centrifugal force to activate it
true
false
True
because of high rotational speeds in steam turbines, it is important that the speed be accurately controlled by 2 systems. operation speed control and over speed control
true
false
True
large steam turbines require intermediate devices to amplify the governors signal into a force powerful enough to operate the control valves. these devices can be
hydraulic
electronic
pneumatic
all the above
All of the above
the governor on a gas turbine is used to monitor the turbine speed and load and adjust the fuel supply accordingly
true
false
True
isocronous control of a governor will keep a constant speed without fluctuation
true
False
True
variable speed control uses centrifugal fly weights and the speed is adjusted by changing the spring pressure that opposes the fly weights
true
False
True
hunting is a problem with some governors. it is the quick action of the governor to the driver speed, causing a to fast, to slow, to fast, to slow cycle. to help alleviate this problem, you would have a governor with speed droop
true
False
True
