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