Chapter 4-7 Flashcards
- What is the main purpose of baffles in the setting of a Boiler?
A) to supply strength to the setting
B) to allow hot gases to make more than one pass through the boiler
C) to produce eddy currents
D) to cause a restriction of gas flow
E) to mix the fuel gas and the combustion air for complete combustion
B) to allow hot gases to make more than one pass through a boiler
- Which of the following are disadvantages of using baffles in a Boiler setting?
1) eddy currents can be produced
2) increased friction can result
3) coal fired boilers can result in pockets of ash accumulation
4) heat transfer is increased.
A) 1,2,3,4
B) 1,2,3
C) 2,4
D) 1,3,4
B) 1,2,3
- In order to direct the flow of combustion gas over the tubes in a watertube boiler, it is necessary to use _____.
A) baffles
B) deflectors
C) fans
D) preheaters
A) baffles
- Baffles can be placed so as to cause the gases to flow at right angles to the tube length, in which case they are called _____ baffles.
A) longitudinal
B) cross
C) back
D) straight
B) cross
- Baffles may be placed so as to cause the gases to flow parallel to the tubes, in which case they are called _____ baffles.
A) longitudinal
B) cross
C) back
D) straight
A) longitudinal
- Baffles are usually constructed of _____ material and may be made up of individual bricks or tiles.
A) steel
B) castable
C) refractory
D) insulation
C) refractory
- Curved or streamlined baffles have the _____ of having no sharp turns to cause eddy currents, increase friction, or form pockets for ash accumulation.
A) disadvantage
B) habit
C) source
D) advantage
D) advantage
- Metal fin bars are welded to adjacent tubes, forming a continuous surface and a pressure tight wall, this is referred to as a welded fin tube wall or a _____ wall.
A) solid
B) membrane
C) screen tube
D) tangent tube
B) membrane
- A wall suitable for severe service, here the tubes are side by side and touching each other, this is called a _____ wall.
A) solid
B) membrane
C) screen tube
D) tangent tube
D) tangent tube
- Flat plates or studs are welded to each side of the tubes, this is called a _____ wall.
A) flat stud tube
B) screen tube
C) tangent tube
D) membrane
A) flat stud tube
- In the watertube boiler, water cooling of the furnace is achieved by arranging tubes to form all or part of the furnace walls. Which of the following refers to this type of construction?
1) tangent tube wall
2) fin welded tubes
3) tube and brick wall
4) flat stud tube wall
A) 1,2,3,4 B) 2,3 C) 2,3,4 D) 1,2 E) 1,3
A) 1,2,3,4
- Steam produced from water in a boiler is at saturation temperature and usually contains a certain amount of moisture. The purpose of the superheater is:
1) to save on chemical make up to the boiler
2) that any moisture present in the steam will be evaporated
3) is to help protect the turbine blades from erosion
4) is to allow more work per kg of steam
A) 1,4 B) 1,2 C) 2,3 D) 2,3,4 E) 2,3
D) 2,3,4
- Which of the following are integral superheaters?
1) high pressure types
2) convection types
3) radiant types
4) high temperature types
A) 1,4 B) 1,3 C) 2,3 D) 3,4 E) 2,4
C) 2,3
- What doe a “rising steam temperature characteristic” mean?
1) at low loads, the steam temperature will be low
2) the superheated steam temperature will rise as the firing rate or boiler output increases
3) at high loads, the steam temperature will be high
4) the temperature of the boiler feedwater rises
A) 1,2,3 B) 2,3 C) 1,3 D) 4 E) 1,4
A) 1,2,3
- Which of the following has a rising steam temperature characteristic?
A) radiant superheater B) pendant superheater C) horizontal superheater D) convection superheater E) separately fired superheater
D) convection superheater
- Which of the following has a falling steam temperature characteristic?
A) radiant superheater B) pendant superheater C) horizontal superheater D) convection superheater E) separately fired superheater
A) radiant superheater
- Which of the following apply to the combination of a radiant superheater and a convection heater?
1) frequently steam generating units have a convection superheater in series with a radiant superheater
2) the steam enters the radiant superheater first and the the convection superheater
3) a fairly steady steam temperature characteristic is produced
4) superheated steam temperatures remain fairly constant at all boiler loads
A) 1,3,4 B) 1,2,3,4 C) 1,2,3 D) 2,3 E) 2,3,4
B) 1,2,3,4
- Which of the following correctly describes the manner in which pendant superheaters are suspended?
A) horizontal B) inclined at an angle of 60 degrees C) vertical D) inclined at an angle of 45 degrees E) inclined at an angle of 30 degrees
C) vertical
- A convection superheater:
A) has the combustion air passing across it
B) is always located in the radiant furnace zone
C) has the hot combustion gases passing over it
D) is located after the economizer
E) is in direct contact with the flame
C) has the hot combustion gases passing over it
- A primary superheater:
A) has the hottest gases passing across it
B) is always located in the radiant furnace zone
C) is the most important superheater
D) receives the saturated steam from the steam drum
E) is always located in the convection zone
D) receives the saturated steam from the steam drum
- Superheated steam:
A) can be produced in the saturated steam drum of a watertube boiler
B) has a temperature that is higher than the saturation temperature for that pressure
C) is almost dry and contains very little moisture
D) cannot be used for sootblowers
E) may cause erosion of turbine blades
B) has a temperature that is higher than the saturation temperature for the pressure
- Which of the following are types of superheaters?
1) primary
2) secondary
3) conduction
4) radiant
5) convection
6) pendant
7) attemperator
A) 1,2,3,4 B) 1,2,4,5,6 C) 1,3,4,5,7 D) 3,4,5,6,7 E) 1,2,3,6,7
B) 1,2,4,5,6
- Steam flow from the steam drum is fed to secondary superheater first and then to primary superheater.
A) true
B) false
B) false
- Which of the following are disadvantages in separately fired superheaters?
1) provide a wider range of temperature control
2) higher initial cost
3) lower operating efficiency
4) larger space requirement
A) 1,2 B) 1,2,3 C) 2,3,4 D) 3,4 E) 1,4
C) 2,3,4
- The separately fired superheater is located in a _____ apart from the main steam generator and is independent of the steam generator operating conditions.
A) boiler
B) furnace
C) building
D) enclosure
B) furnace
- The reheater receives steam, which has already expanded through a portion of the turbine and as a result of this expansion has dropped in pressure and in _____.
A) quality
B) volume
C) temperature
D) energy
C) temperature
- In the reheater, the steam has its temperature raised to about the same temperature as was initially provided by the _____.
A) turbine
B) boiler
C) feedwater
D) superheater
D) superheater
- Reheaters are located in the furnace in areas of relatively _____ gas temperatures.
A) high
B) low
C) moderate
D) average
A) high
- The temperature control methods used for reheater temperature control are the same as those used for _____ temperature control.
A) boiler
B) fuel gas
C) superheater
D) preheater
C) superheater
- The steam flow passes through the reheater immediately after the superheater.
A) true
B) false
B) false
- The two basic types of economizers are:
A) radiant and convection B) integral and sensible C) sensible and radiant D) integral and separate E) recuperative and regenerative
D) integral and separate
- An economizers transfers sensible heat to the feedwater before the feedwater is mixed with the circulating boiler water.
A) true
B) false
A) true
- An economizers is:
1) an energy saving device
2) a Boiler feedwater preheater
3) a device that has water inside tubes and hot gases on the outside
4) a device normally located behind the air preheater
A) 1,2,3,4 B) 1,4 C) 1,3,4 D) 2,3,4 E) 1,2,3
C) 1,3,4
- Which of the following are classifications of economizers?
1) gas type
2) integral type
3) vertical type
4) separate type
A) 1,3 B) 2,4 C) 1,2 D) 3,4 E) 1,4
B) 2,4
- Which of the following types of economizers is the most commonly used?
A) horizontal type B) integral type C) vertical type D) separate type E) gas type
D) separate type
- Which of the following tube types are used on economizers?
1) extended surface tubes
2) U bend tubes
3) continuous tube
4) fin tube
A) 1,2 B) 2,3 C) 2,3,4 D) 1,2,3,4 E) 1,3
D) 1,2,3,4
- What is the main purpose of the cast iron fins on the economizers tubes?
A) added strength B) to prevent corrosion C) increase heat transfer D) none of the above E) to allow hot gases to make more than one pass through a boiler
D) none of the above
- What is the purpose of handholes on certain economizers?
1) used for extra strength
2) used for installation
3) used for repair
4) used for inspection
A) 2,3,4 B) 1,2,3 C) 2,3 D) 1,2,3,4 E) 1,3,4
A) 2,3,4
- Which of the following are advantages of an economizer?
1) not as much Boiler feedwater is required
2) there is less thermal shock to the boiler drum
3) there is not as great a pressure drop through the unit
4) there is an increase in boiler efficiency
A) 1,3 B) 2,4 C) 1,2,3 D) 2,3,4 E) 1,3,4
B) 2,4
- Which of the following are disadvantages of economizers?
1) there is more thermal shock
2) there is increased fan power
3) surfaces must be kept clean to provide increased efficiency
4) more fuel is needed if the boiler has an economizer
A) 1,2 B) 2,3 C) 3,4 D) 2,3,4 E) 1,4
B) 2,3
- Which of the following types of boilers use economizers?
1) watertube boiler
2) firetube boiler
3) electric boiler
4) waste heat boiler
A) 1,3 B) 2,4 C) 2,3,4 D) 1,2,4 E) 3,4
D) 1,2,4
- Which of the following statements apply to air heaters?
1) this is another method of recovering heat from flue gases
2) they are often called air preheaters
3) they consist of a heat exchanger surface located in the path of the combustion gases
4) combustion efficiency is improved
A) 1,2 B) 2,3 C) 1,3,4 D) 1,2,3,4 E) 1,2,3
D) 1,2,3,4
- Which of the following are classes of air heaters?
1) pendant type
2) recuperative type
3) horizontal type
4) regenerative type
A) 1,3 B) 2,4 C) 1,2 D) 3,4 E) 2,3
B) 2,4
- Which of the following refers to recuperative air heaters?
1) they are rotary heaters
2) the heat from the flue gases passes through a plate or tube wall to the air on the other side
3) they are plate type air heaters
4) they are tubular air heaters
A) 1,2 B) 1,4 C) 2,3,4 D) 2,3 E) 1,3
C) 2,3,4
- What is meant by “counter flow” when referring to air heaters?
A) the flue gas and the air pass through alternate passages in opposite directions
B) the flue gas and air pass through alternate passages in the same direction
C) the flue gas and air pass through he same passages in the same direction
D) the flue gas flows through a bypass around the air heater
E) the flue gas and air pass through the same passages in opposite directions
A) the flue gas and the air pass through alternate passages in opposite directions
- The main purpose of the baffles in the tubular air heaters are:
A) to increase to strength of the heater
B) to help prevent corrosion in the heater
C) to act as a restriction for the air flow
D) to direct the air across the tubes in a number of passes
E) to help prevent erosion in the heater
D) to direct the air across the tubes in a number of passes
- Which of the following statements refers to regenerative air heaters?
1) they are stationary type heaters
2) they are rotary type heaters
3) leakage of gas and air is largely prevented by means of radial and circumferential seals
4) they may be arranged in either a vertical or a horizontal manner
A) 1,3,4 B) 1,4 C) 2,3,4 D) 3,4 E) 1,2,3
C) 2,3,4
- Which of the following are advantages of air heaters?
1) they have a low initial cost
2) they increase the efficiency of the boiler
3) they are easily maintained
4) there is increased combustion efficiency
A) 1,3 B) 1,2 C) 2,4 D) 3,4 E) 2,3
C) 2,4
- Which of the following could contribute to air heater corrosion?
1) if the fuel contains sulphur compounds
2) if the output of the air heater is too hot
3) if the output of the air heater approaches the dew point
4) none of the above
A) 1,3 B) 1,2 C) 2 D) 4 E) 1,4
A) 1,3
- The two basic types of preheaters are:
A) recuperative and regenerative B) recuperative and radiant C) convection and radiant D) plate and tube E) convection and regenerative
A) recuperative and regenerative
- Hot spots on tubes not caused by slag are a more serious problem. They indicate poor heat _____ through the tube walls.
A) distribution
B) transfer
C) flux
D) sensor
B) transfer
- Wet tubes on startup of the boiler are a _____ occurrence, caused by condensation on the tube walls.
A) abnormal
B) emergency
C) normal
D) flooding
C) normal
- When starting up a boiler, a steam flow is needed through the _____ tubes for cooling.
A) superheater
B) preheater
C) boiler
D) turbine
A) superheater
- There is no steam flow through the _____ tubes before the steam turbine has a steam flow through it. Be careful not to increase boiler firing too rapidly and overheat the reheat tubes, during startup.
A) superheater
B) economizer
C) reheater
D) boiler
C) reheater
- When starting the boiler, it may be necessary to keep a flow of BFW through the _____ tubes to prevent overheating and fouling.
A) superheater
B) economizer
C) reheater
D) boiler
B) economizer
- The temperatures of the flue gas leaving the preheater must be kept above the _____ to avoid condensation
A) flash point
B) melt point
C) dew point
D) ambient
C) dew point
- When the boiler is shut down, the air preheater should be inspected for signs of _____.
A) wear
B) distortion
C) overheating
D) corrosion
D) corrosion
- The water _____ of the economizer exit is always below that of the steam drum to prevent steaming in the economizer.
A) temperature
B) pressure
C) flow
D) quality
A) temperature
- The water and water/steam mixture in the steam generation tubes is at _____ temperature.
A) superheat
B) critical
C) saturation
D) normal
C) saturation
- The _____ increases the temperature of the steam from the H.P. Turbine back up to superheater temperature.
A) superheater
B) economizer
C) furnace
D) reheater
D) reheater
- The popping pressure of a safety valve must be:
A) lower on the economizer than the main steam drum
B) higher on the main steam drum than the air preheater
C) lower on the main steam drum than the superheater
D) higher on the main steam drum than on the superheater
E) the same on the main steam drum as on the superheater
D) higher on the main steam drum than on the superheater
- Safety valves should be opened manually to:
A) release internal pressure B) remove sludge C) lower boiler water level D) test the operation of the valve E) test the lower water fuel cutoff
D) test the operation of the valve
- Safety valves:
1) prevent loss of production in a plant
2) prevent bursting of the boiler drum
3) release steam to the atmosphere
4) are not required on boilers
A) 1,2,3,4 B) 1,2 C) 2,3 D) 3,4 E) 1,3
C) 2,3
- To increase the popping pressure of a safety valve:
A) the adjusting spring is spewed upward B) the adjusting screw is moved upward C) the adjusting ring is screwed downward D) the adjusting screw is moved downward E) the spring is replaced
D) the adjusting screw is moved downward
- To increase the blowdown of a safety valve:
1) increase the spring tension
2) increase the port openings
3) screw the adjusting spring upwards
4) decrease the port opening
A) 1,2 B) 2,3 C) 2,4 D) 1,3 E) 3,4
E) 3,4
- The purpose of the lip or feather on a safety valve seat:
1) increases the force of steam acting on the seat
2) allows the valve to pop open
3) allows simpler construction of the valve
4) makes no difference in operation
A) 1,2,3,4 B) 1,2 C) 2,3 D) 3,4 E) 1,2,3
B) 1,2
- Safety valves:
1) shall be attached as close as possible to the boiler drum
2) shall be attached in an upright position with the spindle vertical
3) shall have a discharge line attached
4) shall have no valve placed between the boiler and the safety valve
A) 1,2,3,4 B) 1,2,3 C) 1,2,4 D) 2,3,4 E) 1,3,4
C) 1,2,4
- A safety valve:
1) which discharges shall be located or piped clear of platforms or running boards
2) must have a gravity drain installed in the discharge line where condensate may collect
3) shall have an open gravity drain in the valve casing below the seat
4) has no discharge pipes in some cases
A) 1,2,3,4 B) 1,2,3 C) 2,3,4 D) 1,3,4 E) 1,2,4
A) 1,2,3,4
- Every boiler must be fitted with at least one pressure gauge:
A) to indicate the steam flow from the boiler
B) to indicate that it is on or offline
C) to indicate the pressure in the boiler
D) to indicate the pressure in the steam header
E) to indicate the water level in the boiler
C) to indicate the pressure in the boiler
- A water gauge glass:
1) indicates how much steam is in the boiler
2) may be connected directly to the boiler
3) must have a water column connected to the boiler first
4) indicates how much water is in the boiler
A) 1,2,4 B) 2,3,4 C) 1,2 D) 2,4 E) 1,3,4
D) 2,4
- During the operation of a boiler, it is extremely important to maintain the correct water level:
1) to prevent the gas burner from fluctuating
2) to prevent water carry over
3) to prevent hot spots
4) to protect the alternator
A) 1,2,3,4 B) 1,2 C) 1,4 D) 2,3 E) 1,2,3
D) 2,3
- The water column:
1) acts as a reservoir
2) dampens the agitation
3) tends to trap any sludge or sediment
4) provides a place for the installation of alarm floats
A) 1,2,3,4 B) 1,2,3 C) 2,3,4 D) 1,3,4 E) 1,2,4
A) 1,2,3,4
- Water gauge glasses have:
1) quick closing type valves in the steam and waterside
2) valves with convenient handles, that could be remotely operated if needed
3) drain valves, which are slow opening
4) no drain valves
A) 1,2,3,4 B) 1,2,3 C) 1,2,4 D) 2,3,4 E) 1,3,4
B) 1,2,3
- Flat glass gauges;
1) are used for pressures above 2750 kPa
2) are used on water tube boilers only because they are cooler
3) consist of two glass plates, which are bolted to a steel forged housing
4) are lined with him sheets of mica
A) 1,2,3,4 B) 1,2,3 C) 1,3,4 D) 2,3,4 E) 1,2,4
C) 1,3,4
- When repairing a gauge glass:
1) the boiler gauge glass should not be under pressure
2) the steam and water connections should be closed and the drain valve should be open
3) the operator should wear a face shield before pressuring up the glass
4) the steam and water connection should be blown out before installing the new glass
A) 1,2,3,4 B) 1,2,3 C) 2,3,4 D) 1,3,4 E) 1,2,4
A) 1,2,3,4
- Low water fuel cutoffs:
A) cannot be automatically reset B) do not act as an interlock device C) may have a float or electrode chamber D) cannot be adversely effected by heat E) not required on automatically fired steam boilers
C) may have a float or electrode chamber