Chapter 8 Flashcards
- A single element feedwater system compensates for variations in:
A) level and pressure B) shrinkage and swell C) level only D) pressure only E) flow only
C) level only
- With on/off Boiler feedwater control, water is supplied_____ to the boiler, either by fully opening or closing a val e in the feedwater line
A) partially
B) intermittently
C) fully
D) steadily
B) intermittently
- In _____ control, a change in drum level causes a proportional change in output from the transmitter to reposition the feedwater control valve to correct the drum level set point.
A) proportional
B) reset
C) feedback
D) wate
C) feedback
- A rapid increase in boiler load causes an immediate increase in steam flow from the boiler, which creates a sudden _____ in the boiler steam drum pressure.
A) drop
B) increase
C) change
D) temperature
A) drop
- A sudden increase in load, a decrease in drum pressure, and an immediate increase in heat release, is called _____.
A) rate
B) swell
C) shrinkage
D) condensing
B) swell
- The two element feedwater control system, is similar to the single element type, only with a ____ flow transmitter added.
A) fuel
B) feedwater
C) air
D) steam
D) steam
- A two element control system. At be called a _____ system as it anticipates what will happen to the drum level with a change in load and acts accordingly to avoid large level fluctuations.
A) reverse feed
B) feed forward
C) good
D) smart
B) feed forward
- Two element system in feedwater regulation will compensate for:
A) feedwater pressure and level variations
B) shrinkage and swell
C) steam flow variations
D) level, shrinkage, and swell variations
E) level and steam flow variations
D) level, shrinkage, and swell variations
- Shrinkage may be the result of:
1) a reduction in boiler output
2) an increase in firing rate
3) a decrease in firing rate
4) an increase in steam drum pressure
A) 1,3,4 B) 1,2,3 C) 2,3,4 D) 1,2,4 E) 1,2,3,4
A) 1,3,4
- A Steam generator usually has a greater water volume in the tube section than the drum section. Consequently:
A) fuel flow control is most critical B) feedwater control is most critical C) feedwater pressure is most critical D) air flow control is most critical E) steam drum pressure is most critical
B) feedwater control is most critical
- Three element feedwater control compensates for:
1) level variation
2) steam flow variation
3) feedwater flow variation
4) shrinkage and swell
A) 2,3,4 B) 1,3,4 C) 1,2,4 D) 1,2,3,4 E) 1,2,3
D) 1,2,3,4
- The three element feedwater control system overcomes the effects of swell and shrinkage and also responds to _____ flow.
A) fuel
B) steam
C) feedwater
D) blowdown
C) feedwater
- A square root extractor is used to produce an _____ that is proportional to the steam flow.
A) output
B) input
C) setpoint
D) result
A) output
- An increase in boiler load or steam flow causes a proportional increase in the steam flow signal and an increase in output of the computing relay which becomes the set point in the controller.
A) true
B) false
A) true
- A direct pressure combustion control system may be used on boilers where the fuel flow is _____ to measure.
A) easy
B) difficult
C) necessary
D) important
B) difficult
- An oxygen analyzer can also be provided to indicate the excess oxygen in the flue gas, assisting the operator to control the excess air and increasing boiler _____.
A) load
B) firing
C) temperature
D) efficiency
D) efficiency
- Combustion regulation is a function of:
A) steam drum pressure B) fuel flow C) air flow D) fuel/air ratio E) feed water flow
A) steam drum pressure
- A pressure modulating control, or pressuretrol:
A) maintains a constant firing rate
B) will vary fuel and air supply according to steam pressure
C) cannot be adjusted
D) can vary fuel and air supply separately
E) starts and stops the burner at predetermined settings
B) will vary fuel and air supply according to steam pressure
- Direct combustion control measures and responds to:
A) air flow and steam pressure B) air flow and fuel flow C) steam pressure only D) steam pressure and fuel flow E) steam pressure and steam flow
C) steam pressure only
- On a coal fired unit using a stoker and obtaining good combustion efficiency we would probably use:
A) steam flow, air flow control B) fuel flow, air flow control C) air flow, fuel flow control D) direct control E) positioning control
A) steam flow, air flow control