Unit 7 Types of prime movers and Heat engines Flashcards
Using a compressed air starting motor is a common method of starting: Select one: a. Large stationary diesel engines b. Small two-stroke engines c. Gasoline engines d. Aircraft engines
a. Large stationary diesel engines
A steam engine piston:
Select one:
a. Moves fastest at the end of its stroke
b. Produces the most force at the end of its stroke
c. Is lubricated inside the crankcase by the splash method
d. Moves fastest from the start to the mid point of its stroke
d. Moves fastest from the start to the mid point of its stroke
When \_\_\_\_\_\_\_\_\_\_\_\_\_ leached away from cooling tower wood, it is less able to resist decay. Select one: a. sap is b. lignin is c. cellulose is d. natural extractives are
d. natural extractives are
During a single rotation of a 4-stroke cycle gasoline engine crankshaft, the engine undergoes
Select one:
a. a compression stroke, immediately followed by an exhaust stroke
b. an intake stroke, immediately followed by a power stroke
c. an intake stroke, immediately followed by an exhaust stroke
d. a power stroke, immediately followed by an exhaust stroke
d. a power stroke, immediately followed by an exhaust stroke
The slide valve of a steam engine is designed to:
Select one:
a. Drain the condensate from the cylinder during warm-up
b. Provide lubrication for the steam engine
c. Allow steam to enter and leave the cylinder
d. Prevent the engine from over-speeding
c. Allow steam to enter and leave the cylinder
An arrangement of a steam system and a gas turbine, working as a single installation, is called a Select one: a. a combined cycle plant b. a cogeneration system c. a once-through system d. a two-stage system
a. a combined cycle plant
One complete movement of the piston in one direction requires \_\_\_\_\_\_\_\_\_\_\_\_ of the engine crankshaft: Select one: a. One-half revolution b. One revolution c. Two revolutions d. Four revolutions
a. One-half revolution
An engine that has one power stroke every second rotation of the crankshaft is a: Select one: a. two-stroke diesel engine b. four-stroke natural gas engine c. two-stroke gasoline engine d. double-acting engine
b. four-stroke natural gas engine
Excessive wind velocity in a natural draft cooling tower may cause: Select one: a. Damaged louvres b. High drift losses c. Unstable sump water level d. Over-cooling of the water
b. High drift losses
A gas turbine is most efficient when:
Select one:
a. both turbine shafts run at the same speed
b. the combustion chamber is kept cool
c. the ambient air temperature is low
d. operated at the highest combustion temperature that the construction materials permit.
d. operated at the highest combustion temperature that the construction materials permit.
The injection pump of a diesel engine is driven by: Select one: a. Piston action b. The governor c. The gudgeon pin d. A camshaft
d. A camshaft
The output power of a gas turbine depends upon
Select one:
a. the mass of hot gas passing through the turbine per unit time
b. the temperature at the turbine inlet in Kelvin
c. the drive gear ratio between the turbine and compressor
d. the difference between inlet air and turbine exhaust temperature
a. the mass of hot gas passing through the turbine per unit time
Compression ignition engines:
Select one:
a. Mix oil into the fuel for lubrication
b. Will compress air only on the compression stroke
c. Will compress air only on the power stroke
d. Require a spark timing device
b. Will compress air only on the compression stroke
Cylinder scavenging:
Select one:
a. Refers to the flow of fuel air mixture into a diesel engine.
b. Refers to the removal of exhaust gases from the cylinder
c. May be aided with air injectors to rapidly fill the cylinder
d. Is performed by a special piston ring that removes excessive oil from the cylinder walls
b. Refers to the removal of exhaust gases from the cylinder
The turbine overspeed trip:
Select one:
a. Prevents the turbine from exceeding the maximum rated speed
b. Adjusts steam flow to keep the speed at set point
c. Opens the sentinel valve
d. Alerts the operator of excessive turbine RPM
a. Prevents the turbine from exceeding the maximum rated speed
Despite their size and complexity, steam plants are widely used because:
Select one:
a. they are relatively inexpensive to build
b. they do not require trained operators
c. they require little maintenance or repairs
d. they can use a wide variety of heat sources, including hydrocarbon fuels, waste heat, solar energy and nuclear energy.
d. they can use a wide variety of heat sources, including hydrocarbon fuels, waste heat, solar energy and nuclear energy.
A “prime mover” is
Select one:
a. the same as a “heat engine”
b. a device that uses a primary energy source to produce mechanical work
c. a device used to remove air from pumping systems
d. a device that stores mechanical energy, such as a flywheel.
b. a device that uses a primary energy source to produce mechanical work
_______________ causes the fuel to ignite in a diesel engine.
Select one:
a. A precisely timed glow plug.
b. The pressure of the injected fuel.
c. The high temperature compressed air in the engine cylinder.
d. The fuel injector nozzle.
c. The high temperature compressed air in the engine cylinder.
Clean air flows into a gas turbine regenerator from: Select one: a. the inlet air pre-filter b. the combustor c. the gasifier d. the compressor outlet
d. the compressor outlet
In theory, impulse turbines:
Select one:
a. Have a velocity drop through the nozzle
b. Have no pressure drop through the moving blades
c. Can only use only low-pressure steam
d. Develop the most torque of all turbines
b. Have no pressure drop through the moving blades
The turbine overspeed trip:
Select one:
a. Prevents the turbine from exceeding the maximum rated speed
b. Adjusts steam flow to keep the speed at set point
c. Opens the sentinel valve
d. Alerts the operator of excessive turbine RPM
a. Prevents the turbine from exceeding the maximum rated speed
A starting device for a gas turbine
Select one:
a. must be an electric motor
b. is necessary for all gas turbines
c. keeps rotating the turbine shaft until the turbine is up to full load
d. is also called “barring gear”
b. is necessary for all gas turbines
A counter-flow cooling tower \_\_\_\_\_\_\_\_\_\_\_\_\_ than a crossflow cooling tower. Select one: a. is shorter b. requires less floor space c. requires less fan power d. has a lower pressure drop
b. requires less floor space
The reciprocating motion of a steam engine is converted to rotary motion: Select one: a. At the end of the piston stroke b. By the camshaft c. At the crankshaft d. By the valve gear
c. At the crankshaft
A gas turbine compressor:
Select one:
a. must be a multi-stage compressor
b. is always an axial compressor
c. can be driven by the load turbine
d. must be intercooled
c. can be driven by the load turbine
The output power of a gas turbine depends upon
Select one:
a. the mass of hot gas passing through the turbine per unit time
b. the temperature at the turbine inlet in Kelvin
c. the drive gear ratio between the turbine and compressor
d. the difference between inlet air and turbine exhaust temperature
a. the mass of hot gas passing through the turbine per unit time
The injection pump of a diesel engine is driven by: Select one: a. Piston action b. The governor c. The gudgeon pin d. A camshaft
d. A camshaft
Which of the following is a prime mover ? Select one: a. An electric generator b. A gas turbine c. An air compressor d. A boiler
b. A gas turbine
Which of the following comes earliest in the start-up sequence of a steam turbine?
Select one:
a. Open the steam inlet valve slightly to start the turbine rolling.
b. Manually test the overspeed trip.
c. Reset the overspeed trip.
d. Close the casing drain valve and ensure the casing drain steam trap remains in service
c. Reset the overspeed trip.
Despite their size and complexity, steam plants are widely used because:
Select one:
a. they are relatively inexpensive to build
b. they do not require trained operators
c. they require little maintenance or repairs
d. they can use a wide variety of heat sources, including hydrocarbon fuels, waste heat, solar energy and nuclear energy.
d. they can use a wide variety of heat sources, including hydrocarbon fuels, waste heat, solar energy and nuclear energy.
One complete movement of the piston in one direction requires \_\_\_\_\_\_\_\_\_\_\_\_ of the engine crankshaft: Select one: a. One-half revolution b. One revolution c. Two revolutions d. Four revolutions
a. One-half revolution
An essential auxiliary in a gas turbine installation is: Select one: a. an air heater b. a generator c. a water injection system d. a starting motor
d. a starting motor
A major difficulty encountered with a two-stroke cycle engine is:
Select one:
a. The lack of torque at high speed
b. The difficulty in cold weather starting
c. The high speeds compared to an equivalent four-stroke engine
d. Exhausting the spent gases from the cylinder
d. Exhausting the spent gases from the cylinder
A gas turbine:
Select one:
a. Expands hot gases through the compressor
b. Output increases when using air of maximum density
c. Operates the best when the inlet air is hot
d. Output increases when equipped with an air preheater
b. Output increases when using air of maximum density
The fuel for a diesel engine is:
Select one:
a. admitted to the cylinder during the intake stroke
b. mechanically atomized by high pressure
c. fed to the carburetor under pressure
d. mixed with air in the intake manifold
b. mechanically atomized by high pressure
The purpose of a spark plug is to: Select one: a. Ignite the fuel air mixture in a gasoline engine b. Warm the cylinder of a diesel engine c. Lower the ignition point of the fuel d. Ignite the air in the cylinder
a. Ignite the fuel air mixture in a gasoline engine
Turbine lubricating oil: Select one: a. Contaminates the exhaust steam b. Must mix well with water c. Can be used to operate the turbine governor d. Lubricates the labyrinth gland
c. Can be used to operate the turbine governor
The purpose of turbine glands is to prevent:
Select one:
a. cool and lubricate the shaft
b. Steam escaping from the turbine
c. Steam from entering the lubrication system
d. shaft movement due to axial thrust
b. Steam escaping from the turbine
Between a valve and a pushrod, there is a
Select one:
a. rocker arm
b. connecting rod
c. wrist pin
d. camshaft
a. rocker arm
A “heat engine” is an operating cycle that uses a working fluid to convert:
Select one:
a. Thermal energy to chemical energy
b. Thermal energy to potential energy
c. Mechanical energy to electrical energy
d. Thermal energy to mechanical energy
d. Thermal energy to mechanical energy
Some of the characteristics that make the gas turbine a better choice over other prime movers are:
Select one:
a. its low power-to-weight ratio
b. its high thermal efficiency
c. its ability to rapidly start and carry full load
d. its low fuel consumption
e. Increased power output at higher elevations
c. its ability to rapidly start and carry full load
Which of these is not a type of condenser used in a steam power plant?
Select one:
a. Vacuum condenser
b. Contact condenser
c. Barometric condenser
d. Surface condenser
a. Vacuum condenser
For economical operation, the steam supply to a steam engine is cut off once the piston has traveled \_\_\_\_\_\_\_ of its stroke. Select one: a. 1/4 to 1/3 b. 75% to 90% c. 1/2 to 5/8 d. 100%
a. 1/4 to 1/3
The connecting rods of a steam engine:
Select one:
a. Convert reciprocating motion to rotary motion
b. Are used to move the slide valve
c. Are only needed on vertical engines
d. Connects the inlet valve to the discharge valve
a. Convert reciprocating motion to rotary motion
Biological attack on cooling tower wood affects the
Select one:
a. chemicals that cement the cellulose fibres together.
b. natural extractives.
c. cellulose.
d. lignin.
c. cellulose.
Cylinder scavenging:
Select one:
a. Refers to the flow of fuel air mixture into a diesel engine.
b. Refers to the removal of exhaust gases from the cylinder
c. May be aided with air injectors to rapidly fill the cylinder
d. Is performed by a special piston ring that removes excessive oil from the cylinder walls
b. Refers to the removal of exhaust gases from the cylinder
Rotating blades or "\_\_\_\_\_\_\_\_" form the steam flow passages in impulse turbines. Select one: a. Buckets b. Pails c. Ports d. Diaphragms
a. Buckets
A closed cycle gas turbine: Select one: a. Does not need a combustion chamber b. Is the most common type of gas turbine c. Recycles the same working fluid d. Burns fuel with spent exhaust gas.
c. Recycles the same working fluid
In a diesel engine, an injection nozzle is used for \_\_\_\_\_\_\_\_\_\_\_ Select one: a. Lubricating the journal bearings b. Scavenging the cylinder c. Igniting the fuel. d. Atomizing the fuel.
d. Atomizing the fuel.
An arrangement of a steam system and a gas turbine, working as a single installation, is called a Select one: a. a combined cycle plant b. a cogeneration system c. a once-through system d. a two-stage system
a. a combined cycle plant
On steam turbines, carbon glands are: Select one: a. Lubricated by the main oil pump b. Lubricated by the seal oil pump c. Lubricated by governor oil d. Self-lubricating
d. Self-lubricating
Large internal combustion engines are cooled with:
Select one:
a. Water jackets
b. Large fans
c. Air cooling fins on the cylinder jackets
d. Condensers
a. Water jackets
Most modern gas turbines use a ______________ shaft design.
Select one:
a. two
b. locked
c. single
d. three
c. single
The hand wheel used to adjust the turbine speed on the governor is known as the: Select one: a. Driver b. Setter c. Throttle d. Speeder
d. Speeder
Diesel engine governing is accomplished by:
Select one:
a. varying the load on the engine
b. varying the amount of air-fuel mixture drawn into the engine when the load changes
c. varying the amount of fuel injected on each power stroke
d. modulating the pressure of the atomizing air.
c. varying the amount of fuel injected on each power stroke
Turbines often have segmental carbon ring sealing glands that are held in place by: Select one: a. Set screws b. Woodruff keys c. Oil pressure d. Garter springs
d. Garter springs
Smaller spark ignition engine use \_\_\_\_\_\_\_\_\_\_\_\_ to vapourize gasoline: Select one: a. Vapourizers b. Atomization c. Electric heaters d. Carburetion
d. Carburetion
The shrouding on the blades of a steam turbine serves to: Select one: a. Cool the blade tips b. Expand the steam like a nozzle c. Change the steam direction d. Confine the steam to the blades
d. Confine the steam to the blades
The part of a camshaft that converts rotary motion to reciprocating motion is called
Select one:
a. the lifter
b. the lobe
c. the journal
d. the pushrod
b. the lobe
The rotating passages of a reaction turbine are mounted on the: Select one: a. Rotor b. Shroud ring c. Casing d. Diaphragm
a. Rotor
The low installation cost of a gas turbine is:
Select one:
a. due to less costly construction materials
b. because the cooling tower can be much smaller
c. still higher than a steam plant installation
d. because less auxiliary equipment is needed
d. because less auxiliary equipment is needed
A turbine overspeed trip:
Select one:
a. Trips the turbine if it is overloaded
b. Is installed on all turbines
c. Can be adjusted according to the load demand
d. Disconnects the turbine load if the turbine overspeeds
b. Is installed on all turbines
Excessive wind velocity in a natural draft cooling tower may cause: Select one: a. Damaged louvres b. High drift losses c. Unstable sump water level d. Over-cooling of the water
b. High drift losses
A gas turbine is most efficient when:
Select one:
a. both turbine shafts run at the same speed
b. the combustion chamber is kept cool
c. the ambient air temperature is low
d. operated at the highest combustion temperature that the construction materials permit.
d. operated at the highest combustion temperature that the construction materials permit.
A steam engine’s crosshead:
Select one:
a. Imparts angular motion to the piston rod
b. Converts linear motion of the piston rod into angular motion
c. Does not require any lubrication
d. Is often called the “gudgeon”.
b. Converts linear motion of the piston rod into angular motion
A steam engine piston:
Select one:
a. Moves fastest at the end of its stroke
b. Produces the most force at the end of its stroke
c. Is lubricated inside the crankcase by the splash method
d. Moves fastest from the start to the mid point of its stroke
d. Moves fastest from the start to the mid point of its stroke
The rate of heat transfer in any cooling tower system depends on the:
Select one:
a. The difference between the inlet air relative humidity and the inlet air absolute humidity.
b. The difference between the temperature of the water in and the temperature of the air out.
c. The amount and temperature of the make-up water
d. The difference between the inlet water temperature and the inlet air wet bulb temperature
d. The difference between the inlet water temperature and the inlet air wet bulb temperature
The purpose of a regenerator is to:
Select one:
a. Re-circulate the exhaust gases back through the compressor
b. Improve the efficiency of the turbine
c. Increase the temperature in the combustion chamber
d. Cool the gas entering the compressor
b. Improve the efficiency of the turbine
A cold weather cooling tower bypass valve should not be fully closed until the temperature reaches: Select one: a. the compressor setpoint b. the point at which drift stops c. +5°C d. about 27°C
d. about 27°C
A two-cycle gasoline engine:
Select one:
a. produces twice the power of a four cycle
b. must have two cylinders
c. requires exhaust valves
d. is simpler than a four cycle engine in construction
d. is simpler than a four cycle engine in construction
Internal combustion engines that drive gas compression machinery, and burn natural gas, operate on the \_\_\_\_\_\_\_\_ cycle. Select one: a. rotary b. variable heat c. two or four stroke d. Brayton
. two or four stroke
The impulse turbine works on the principle that:
Select one:
a. Kinetic energy can be converted to mechanical energy
b. Steam expansion in the moving blades creates a force impulse
c. The high pressure creates unbalanced forces on the blades
d. High velocity steam exerts force upon the rotating blades due to change in momentum.
d. High velocity steam exerts force upon the rotating blades due to change in momentum.
A simple gas turbine is one without reheaters or: Select one: a. Starting motors b. Compressors c. Combustors d. Regenerators
d. Regenerators
The combustion chamber of a gas turbine:
Select one:
a. increases the density of the compressed air.
b. must be water cooled to protect against high temperature.
c. is where fuel is added to air, and burned.
d. preheats the combustion air before it is compressed.
c. is where fuel is added to air, and burned.
Diesel engines require: Select one: a. A carburetor b. A magneto c. A fuel injector d. An ignition coil
c. A fuel injector
A two shaft gas turbine: Select one: a. has the load turbine downstream from the compressor turbine b. is always an open cycle c. uses two shafts, geared together d. is always regenerative
a. has the load turbine downstream from the compressor turbine
Four-stroke cycle engine valves are:
Select one:
a. Operated by camshafts
b. Operated by pressure differential
c. Often called “reed” or “channel” valves
d. Open whenever the piston travels upward
a. Operated by camshafts
When starting a steam turbine it is customary practice to:
Select one:
a. first, rotate the shaft by hand to see if it turns freely.
b. check the lube oil and start the lube oil cooler before starting the turbine.
c. close the turbine casing drains and steam trap bypasses until the turbine is fully warmed.
d. overspeed the turbine to test the operation of the overspeed trip, before continuing with the turbine warm-up.
b. check the lube oil and start the lube oil cooler before starting the turbine
A gas turbine must be rotated at \_\_\_\_\_\_\_ speed before ignition begins. Select one: a. 10% of its maximum b. 120% of its maximum c. 20% to 30% of its maximum d. full
c. 20% to 30% of its maximum
During a single rotation of a 4-stroke cycle gasoline engine crankshaft, the engine undergoes
Select one:
a. an intake stroke, immediately followed by an exhaust stroke
b. a compression stroke, immediately followed by an exhaust stroke
c. an intake stroke, immediately followed by a power stroke
d. a power stroke, immediately followed by an exhaust stroke
d. a power stroke, immediately followed by an exhaust stroke
A reduction in sealing between the piston rings and the cylinder wall may be the result of: Select one: a. Low cooling water temperature b. High oil viscosity c. High coolant temperature d. High carbon residue in the oil
c. High coolant temperature
In a reaction turbine the steam \_\_\_\_\_\_\_\_\_\_\_\_ when passing through moving blades. Select one: a. Pressure increases b. Pressure decreases c. Velocity remains constant d. Velocity decreases
b. Pressure decreases
Natural draft cooling towers operate most effectively in large open spaces and: Select one: a. Where wind is relatively constant b. Where relative humidity is high c. Where a large body of water is nearby d. With large refrigeration systems
a. Where wind is relatively constant
Large four-cycle engines are usually lubricated with Select one: a. oil, fed under pressure by a pump b. oil rings c. oil pre-mixed with fuel d. splash lubrication
a. oil, fed under pressure by a pump
Gas turbines are ideal where: Select one: a. noise is undesirable b. water is scarce c. thermal pollution is of major concern d. waste heat can be discharged into the atmosphere
b. water is scarce
When the steam pressure drop occurs only in the stationary steam passages, the turbine is known as: Select one: a. An impulse turbine b. A reaction turbine c. A Parsons turbine d. A single stage turbine
a. An impulse turbine
Water is removed from the air stream leaving a cooling tower, using Select one: a. fill or packing b. desiccant c. cyclone separators d. drift eliminators
d. drift eliminators
One of the ways to detect a fault in a reciprocating steam engine is by:
Select one:
a. monitoring changes in its sound
b. adding oil to the lubricators
c. examining how much oil leaves with the exhaust steam
d. seeing if it runs properly in reverse as well as in forward.
a. monitoring changes in its sound
Clean air flows into a gas turbine regenerator from: Select one: a. the inlet air pre-filter b. the combustor c. the gasifier d. the compressor outlet
d. the compressor outlet
A routine inspection of an operating steam engine should start with:
Select one:
a. making sure the lubricators are feeding properly.
b. blowing off the steam chest drains.
c. checking the boiler pressure.
d. checking the load on the engine.
a. making sure the lubricators are feeding properly.
When using injected compressed air to start a diesel engine, the air pressure is approximately: Select one: a. 520 kPa b. 255 kPa c. 3030 kPa d. 2100 kPa
d. 2100 kPa
Steam turbine governors:
Select one:
a. prevent the turbine from over speeding
b. regulate the speed of the turbine automatically
c. Should be checked annually by the boiler inspector
d. Are not required on reaction turbines
b. regulate the speed of the turbine automatically
Shaft sealing of small steam turbines is done with: Select one: a. rope packing and lantern rings b. Carbon rings c. Labyrinth glands d. Mechanical seals
b. Carbon rings
Natural draft cooling towers are divided into:
Select one:
a. Dry and wet types
b. Updraft and down-draft types
c. Atmospheric towers and chimney towers
d. Wood fill and plastic fill types
c. Atmospheric towers and chimney towers
An advantage of gas turbines over other types of prime movers, is that gas turbines:
Select one:
a. have high thermal efficiencies
b. need very little lubrication
c. require little to no cooling water
d. are reversible
c. require little to no cooling water
An engine that has one power stroke every second rotation of the crankshaft is a: Select one: a. two-stroke diesel engine b. four-stroke natural gas engine c. two-stroke gasoline engine d. double-acting engine
b. four-stroke natural gas engine
The shafts of high output, high temperature steam turbines are usually sealed using: Select one: a. Garter springs b. Carbon rings c. Packing rings d. Labyrinth glands
d. Labyrinth glands
In impulse turbine theory, the:
Select one:
a. Steam flow is reduced through the nozzles
b. Steam pressure is reduced in the nozzles
c. Steam pressure decreases across the rotating blades
d. Steam velocity increases through the rotating blades
b. Steam pressure is reduced in the nozzles
As the temperature of the air drawn into a gas turbine compressor increases, the ____________________ of the gas turbine _________________.
Select one:
a. RPM, decreases
b. RPM, increases
c. output power, decreases
d. output power, increases
c. output power, decreases
To prevent cooling tower basin water from freezing during cold weather, many units:
Select one:
a. have automatic ethylene glycol antifreeze injection systems.
b. have thermostatically controlled electric basin heaters.
c. have automatic gas-fired sump heaters .
d. use salt brine instead of water.
b. have thermostatically controlled electric basin heaters.
