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
- By measuring and comparing the steam and the _____, it is possible to obtain efficient combustion in a boiler by maintaining a proper steam to air flow ratio.
A) feedwater
B) fuel
C) air flow
D) drum level
C) air flow
- In coal fed to furnaces, the air flow is measured and maintained in a predetermined ratio with the steam flow.
A) true
B) false
A) true
- The furnace pressure controller will adjust the boiler _____ dampers to keep the pressures constant at all boiler loads.
A) outlet
B) inlet
C) air
D) burner
A) outlet
- In a fuel flow, air flow combustion control system, the fuel and air flows are measured directly and are converted to _____ signals by means of square root extractors.
A) digital
B) parallel
C) proportional
D) output
C) proportional
- In a fuel flow airflow combustion system, the fuel flow signal makes the final adjustment to the _____.
A) feedwater
B) fuel
C) airflow
D) drum level
C) airflow
- 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
- 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
- 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
- In a air flow combustion control, air flow signal becomes the set point of the _____ controller.
A) feedwater
B) fuel
C) airflow
D) drum level
B) fuel
- 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
- 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
- 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 control C) fuel flow, air flow control D) air flow, fuel flow control E) steam flow, air flow control
A) multi element control
- The attemperator is used to control the temperature of feedwater from the economizer.
A) true
B) false
B) false
- 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
- There are two types of attemperators used:
A) surface type B) spray type C) direct contact type D) crossflow type E) a,d F) a,c
F) a,c
- 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
- 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
- The gas recirculation method is used to maintain the desired steam temperature at _____ loads.
A) high
B) partial
C) over
D) no
B) partial
- 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
- 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
- At low loads when steam temperature drops, the tilting burners are tilted _____.
A) downwards
B) upwards
C) tangents
D) sideways
B) upwards
- Programming controls:
A) function during operation B) function during startup and shutdown C) function during startup D) function during shutdown E) function during emergency situation
B) function during startup and shutdown
- 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
- 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
- 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
- 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 handheld 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
- 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
- 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
- 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
- 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
- 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 deenergized
D) the timer causes the fuel valve to close
E) the flame scanner becomes deenergized
C) the coil of the burner valve is deenergized
