Chapter 8 Flashcards
The principle of a 3 element feed water control is:
A) For every Kg of steam produced a kg of water should be equally added
B) To compare the outputs of the drum level, steam flow and shrinkage
C) To compare the outputs of the fuel gas, steam flow and drum level
D) To compare the outputs of the fuel gas, steam flow and shrinkage
A
Three element feed water control incorporates:
A) Steam flow, water flow and fuel gas flow
B) Water flow, fuel gas flow and level
C) Level, fuel gas flow and water flow
D) Level, Steam flow and water flow
D
The biggest disadvantage to the direct pressure or parallel positioning combustion control system is:
A) The output of the summing relays becomes the set point for the feed water
B) The correct ratio between air and fuel may not be obtained at all loads
C) Positioning of the airflow damper and excess air can only be achieved automatically
D) No pressure to control of air damper
B
Semi metering control is used as a:
A) Measurement between of fuel and air flow
B) Measurement of calorific heating value and boiler feed water flow
C) Measurement when fuel flow is difficult or impossible to measure
D) Measurement of calorific heating value and air flow
C
The function of a multi-element combustion system is:
A) Efficiency
B) Attemperation
C) Gas recirculation
D) Swell and Shrinkage control
A
When boiler load increases, the _________________ is increased before the fuel to prevent unsafe combustion conditions in the boiler.
A) Boiler feed water flow
B) Fuel flow
C) Steam flow
D) Air flow
D
Attemperation involves:
A) Gas recirculation
B) Temperature boost through the economizer
C) Semi metering control
D) Removal of heat from the super-heaters
D
Tilting burners down at high load conditions provides an:
A) Decrease of heat absorbed to furnace walls and an increase in the super heater section
B) Increase of heat absorbed to furnace walls and a decrease in the super heater section
C) Decrease of heat absorbed to furnace walls and a decrease in the super heater section
D) Increase of heat absorbed to furnace walls and a increase in the super heater section
B
If the pilot burner fails to light during start-up, a _______________ will be energized, which cuts off the power to the ignitor, pilot and main gas valve.
A) Thermostat switch
B) Limiting switch
C) Shut down switch
D) Lock out switch
D
Gas recirculation involves taking a portion of gas from the:
A) Super-heater section and returning it back to the lower part of the furnace
B) Re-heater section and returning it back to the lower part of the furnace
C) Secondary super-heater section and returning it back to the lower part of the furnace
D) Economizer section and returning it back to the lower part of the furnace
D
