Ch. 8 Flashcards
1
Q
- 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
A
c. Level only
2
Q
- With On - Off boiler feed water control, water is supplied _____________ to the boiler, either by fully opening or fully closing a valve in the feedwater line.
a. partially
b. intermittently
c. fully
d. steadily
A
b. intermittently
3
Q
- 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 setpoint.
a. proportional
b. reset
c. feedback
d. water
A
c. feedback
4
Q
- 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
a. drop
5
Q
- A sudden increase in load, a decrease in drum pressure, & an immediate increase in heat release, is called__.
a. rate
b. swell
c. shrinkage
d. condensing
A
b. swell
6
Q
- 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
A
d. steam
7
Q
- A two-element control system may 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
A
b. feed-forward
8
Q
- 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
A
d. Level, shrinkage and swell variations
9
Q
- 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
a. 1, 3, 4
10
Q
- A steam generator usually has a greater water volume in the tube section than 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
A
b. Feedwater control is most critical
11
Q
- 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
A
d. 1, 2, 3, 4
12
Q
- 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
A
c. feedwater
13
Q
- 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
a. output
14
Q
- 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
a. True
15
Q
- 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
A
b. difficult
16
Q
- 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
A
d. efficiency
17
Q
- 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
a. Steam drum pressure
18
Q
- A pressure modulating control (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
A
b. Will vary fuel and air supply according to steam pressure
19
Q
- 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
A
c. Steam pressure only
20
Q
- 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
a. Steam flow-air flow control
21
Q
- By measuring and comparing the steam and the ________, it is possible to obtain efficient combustion in a boiler by maintaining a proper steam to airflow ratio.
a. feedwater
b. fuel
c. airflow
d. drum level
A
c. airflow
22
Q
- In coal fed to furnaces, the airflow is measured and maintained in a predetermined ratio with the steam flow.
a. True
b. False
A
a. True
23
Q
- The furnace pressure controller will adjust the boiler ______ dampers to keep the pressure constant at all boiler loads.
a. outlet
b. inlet
c. air
d. burner
A
a. outlet
24
Q
- In a fuel flow-airflow combustion control system, the fuel and airflows are measured directly and are converted to _________ signals by means of square root extractors.
a. digital
b. parallel
c. proportional
d. output
A
c. proportional
25
478. In a fuel flow-airflow combustion control system, the fuel flow signal makes the final adjustment to the ____.
a. feedwater
b. fuel
c. airflow
d. drum level
c. airflow
26
479. When increasing the firing rate manually it is best to:
a. Increase air flow before fuel flow
b. Increase fuel flow before air flow
c. Increase air and fuel together
d. It really doesn't matter
e. Decrease fuel flow before increasing air flow
a. Increase air flow before fuel flow
27
480. Before making adjustments or altering the fuel-air ratio of a combustion control system, we would:
a. Measure fuel flow
b. Analyze flue gas
c. Increase air flow
d. Decrease firing rate
e. Measure steam flow
b. Analyze flue gas
28
481. When master controller output goes directly to a fuel valve and a modulating relay we have:
a. Multi-element control
b. Air flow-fuel flow control
c. Fuel flow-air flow control
d. Steam flow-air flow control
e. Positioning Control
c. Fuel flow-air flow control
29
482. In a airflow-fuel flow combustion control, airflow signal becomes the set point of the ____ controller.
a. feedwater
b. fuel
c. airflow
d. drum level
b. fuel
30
483. List the main components of a multi-element combustion system:
1) Hand/automatic transfer station
2) Square root extractor
3) Digital conditioner
4) Low select signal relay
5) Signal coupler
6) High select signal relay
7) Local controller
8) Master pressure controller
a. 1, 2, 3, 4, 5
b. 4, 5, 6, 7, 8
c. 1, 2, 4, 6, 8
d. 3, 5, 7, 8
e. 2, 3, 6, 7
c. 1, 2, 4, 6, 8
31
484. An increase in boiler load will cause the airflow to increase first and the increase in gas flow will follow.
a. True
b. False
a. True
32
485. When flue gas is analyzed continuously and the result transmitted into the combustion control loop we have:
a. Multi-element control
b. Flue gas-fuel flow control
c. Fuel flow-air flow control
d. Air flow-fuel flow control
e. Steam flow - air flow control
a. Multi-element control
33
486. The attemperator is used to control the temperature of feedwater from the economizer.
a. True
b. False
b. False
34
487. To maintain turbine __________ and avoid fluctuations in the turbine metal temperatures, it is necessary to hold the superheated steam temperature and the reheated steam temperature, at a constant value.
a. life
b. integrity
c. efficiency
d. operation
c. efficiency
35
488. There are two types of attemperators used:
a. Surface type
b. Spray type
c. Direct contact type
d. Cross flow type
e. A, D
f. A, C
f. A, C
36
489. The direct contact attemperator, which is also referred to as the ______ type desuperheater, introduces feedwater into the superheated steam, through a spray nozzle.
a. shell
b. spray
c. drum
d. condenser
b. spray
37
490. The ______ ,used in the spray desuperheater, must be of the highest quality since any solids carried over will cause deposits in superheater tubes and on turbine blades.
a. steam
b. metal
c. water
d. internals
c. water
38
491. The Gas Recirculation method is used to maintain the desired steam temperature at ________ loads.
a. high
b. partial
c. over
d. no
b. partial
39
492. Gas bypass method involves the separation of the convection section of the boiler into two, or more, _________ gas passes.
a. reverse
b. crossing
c. parallel
d. counter
c. parallel
40
493. At high loads when steam temperature tends to go above the desired value, the tilting burners are tilted ___.
a. downwards
b. upwards
c. tangents
d. sideways
a. downwards
41
494. At low loads when the steam temperature drops, the tilting burners are tilted _________.
a. downwards
b. upwards
c. tangents
d. sideways
b. upwards
42
495. Programming controls:
a. Function during operation
b. Function during start up and shut down
c. Function during start up
d. Function during shut down
e. Function during emergency situations
b. Function during start up and shut down
43
496. On a semi-automatic boiler the programming controls are activated by:
a. Pressure
b. The operator
c. Temperature
d. Water level
e. Temperature and pressure
b. The operator
44
497. Purging a furnace means:
a. Ensuring the furnace is pressurized with air
b. Ensuring air is flowing through the furnace
c. Ensuring fuel is entering the furnace
d. Causing air to flow for no more than five seconds
e. Ensuring the air flow to the furnace has stopped
b. Ensuring air is flowing through the furnace
45
498. Pilot gas valve and ignition transformer should be energized:
a. Before pre purge
b. During post purge
c. After pre purge
d. On program start
e. After the pilot burner is lit
c. After pre purge
46
499. A small automatic oil-fired boiler may light:
1) From an interrupted pilot
2) Directly from the igniter
3) Without a pilot flame
4) From a hand held torch
a. 1, 2, 3
b. 1, 2, 4
c. 1, 3, 4
d. 2, 3, 4
e. 1, 2, 3, 4
a. 1, 2, 3
47
500. All programmers have:
a. Purge times for post-purging
b. Pre-purge timers
c. Lead sulphide cells
d. Flame relays
e. Mercury switch
d. Flame relays
48
501. Limit switches of a programmed circuit tend to be:
a. In parallel
b. Normally closed
c. In series
d. Activated by the programmer
e. Supervise the pilot flame
c. In series
49
502. When we manually close the start switch we:
a. Close the fan circuit
b. Energize the programmer
c. Close the timer circuit
d. Initiate the purge dampers
e. Energize the spark igniter
c. Close the timer circuit
50
503. At the end of the pre-purge the timer:
a. Opens the fuel valve
b. Opens the pilot valve
c. Goes through an ignition trial
d. Energizes the ignition transformer
e. Shuts off the igniter and the pilot
d. Energizes the ignition transformer
51
504. When steam pressure reaches cut-out value:
a. The timer stops
b. The master relay becomes energized
c. The coil of the burner valve is de-energized
d. The timer causes the fuel valve to close
e. The flame scanner becomes de-energized
c. The coil of the burner valve is de-energized
