55 terms

Boiler Design-BLOWDOWN-PREP

STUDY
PLAY
A straight tube longitudinal drum boiler with a chain grate
stoker usually had
a) one pass
b) two passes
c) three passes
d) four passes
e) an internal furnace
C
The Haycock boiler was
a) a watertube unit
b) of multiple flue gas pass design
c) used around 1720
d) of welded construction
e) a packaged unit
C
A characteristic which made early boilers very inefficient was
a) lack of heating surface
b) an excess of flat surfaces
c) the internal furnace
d) lack of good quality fuels
e) inadequate water treatment
A
An early boiler having a longitudinal shell or drum had as its heating surface
a) only the lower part of the shell
b) the lower part of the shell and the rear plate or head
c) the total shell side and one end plate or head
d) only the one end plate
e) two passes along the shell or drum
A
Thermal flooding boilers
a) are often termed "Hot Water Boilers"
b) are low capacity units
c) are used to inject steam into geological formations
d) do not use water as the heat transfer medium
e) are used in the generation of electricity
C
The first boiler to have an internal furnace was the
a) HRT boiler
b) Scotch boiler
c) longitudinal drum firetube boiler
d) locomotive boiler
e) watertube boiler
B
A _________________ is a water-filled section which
surrounds the firebox in locomotive boilers.
a) crown sheet
b) boiler drum
c) tell tale stay
d) steam dome
e) water leg
E
The first boiler to have firetubes became known as the
a) Haycock boiler
b) Scotch boiler
c) Mushroom boiler
d) Haystack boiler
e) HRT boiler
E
The water leg was introduced with the
a) scotch boiler
b) longitudinal drum boiler
c) watertube boiler
d) locomotive boiler
e) HRT boiler
D
Safety, efficient operation, and economical fuel consumption are
a) main considerations when designing boilers
b) the main advantages of a watertube unit over a
firetube unit
c) the result of "packaged unit" construction
d) due to improved metals and alloys
e) the results of environmental protection laws
A
Before starting up any boiler it is necessary that
a) it be properly warmed up
b) it be properly purged
c) it have a valid inspection certificate
d) the water supply system be in service
e) the waterside is boiled out
C
New refractory must be thoroughly and properly cured with a light fire because
a) of its high rate of differential expansion
b) it may burn if not cured
c) it may corrode if not cured
d) it contains moisture which can cause it to fracture if not cured
e) of the length of time it takes it to heat up
D
The external inspection of a boiler
a) may include making sure the valves are in good operating condition
b) may include making sure the furnace refractory is in order
c) may include making sure the tubes are free of scale
d) must be done after the boiler has been drained e) may include making sure the exterior of the tubes are in good condition
A
A boiler inspection
a) must be done after every shut down of the boiler b) must be done when the boiler inspector requests it
c) must be done every two years
d) is done with the owner's permission only
e) must be done before the boiler is ready for start-up
B
The first duty of the operator coming on shift is to
a) check the safety valve settings 290
b) fill out the log book
c) check that water column and gage glass connections are clear
d) talk to his supervisor
e) check the chemical tank levels
C
If a new boiler is not properly boiled out, it may result in
a) tubes rupturing
b) a furnace explosion
c) nuisance shutdowns
d) an unwanted high rate of water circulation
e) a foaming condition occurring
E
Before lighting up a boiler you should:
1) purge the furnace
2) open the blow down valve
3) check the fuel supply
4) fill the boiler with water
a) 1, 2, 4
b) 2, 3, 4
c) 1, 2, 3, 4
d) 1, 3, 4
e) 2, 3
D
Boiler boiling out procedure should be done
a) at operating pressure
b) before the dry out procedure
c) at one-half the operating pressure
d) once a year
e) just before the annual inspection
C
Boiler dry-out means
a) drying out the top and bottom drum
b) igniting the dryers in the top drum
c) drying out the new refractory
d) empty the boiler out
e) drying out the entire boiler before start-up
C
When raising pressure in a firetube boiler you should:
1. raise steam slowly
2. raise steam as rapidly as possible
3. check the furnace frequently
4. check the system for leaks
a) 2, 3, 4
b) 1, 2, 3, 4
c) 1, 3, 4
d) 1, 2, 3
e) 2, 4
C
Before removing a boiler from service for maintenance purposes it is beneficial to
a) inform the Chief Inspector
b) do as little as possible with the waterside of the unit
c) use sootblowers and clean the fireside well
d) force cool the unit with post-purge air
e) drain the unit before the water cools to ambient temperature
C
On boiler cool-down the vent should be opened
a) as soon as the post-purge is completed
b) when all temperatures are at ambient value
c) any time after the NRV is closed
d) just before the unit goes into a vacuum
e) at no time
D
When cooling down a steam boiler that has been taken out of service, a vent valve on the steam drum should be opened to
a) prevent a vacuum from forming in the boiler
b) release the air from the boiler
c) purge the shell of impure gases
d) let the operator know when the pressure has reached zero
e) prevent pressure build-up in the boiler
A
A wide and rapid fluctuating water level in the boiler gage glass may be the result of
a) high TDS
b) a vapour bound boiler feed pump
c) low alkalinity
d) low pH
e) boiler firing rate being too low
A
A natural gas fired power boiler flame should be
a) very slow, long, and mostly yellow or orange
b) fairly rapid, mostly blue, and some orange
c) very rapid, short, very audible, and have no orange
d) very white and intense, requiring coloured glass for viewing
e) bright enough to require coloured glass for viewing
B
When performing a sootblowing operation it is important to maintain flame stability and
a) ensure drum water level remains constant
b) firing rate not be allowed to increase
c) stack discharge not become visible
d) dislodged soot and ash leave the boiler with the flue gases
e) the local environmental agency be notified prior to blowing
D
While blowing down a boiler which is in operation, you should
a) check the rest of the boiler room equipment
b) fill in the log book for your shift
c) concentrate only on blowing down the boiler
d) clean up the area close to the boiler
e) add more water to the boiler to replace the blow down water
C
In the event of a low water condition in a boiler the engineer in charge should
a) shut down the burner immediately
b) continue firing and restore the level
c) shut down the burner, let the unit cool, then inspect it
d) shut down the burner, let the unit cool, then restore level
e) notify the Chief Engineer before responding to the condition
C
A high water level in a boiler
a) will not be made worse by dropping boiler pressure or allowing "swell" to occur
b) should cause a high water level shutdown switch to stop the fire
c) is usually the result of a boiler feedpump malfunction
d) will necessitate an immediate shutdown, cool down, and inspection
e) is usually the result of a level control malfunction
E
When you first notice that the water level in the boiler gauge glass can no longer be seen, it is best first to
a) ensure that the boiler is not over filled
b) start the stand-by feed pump or injector
c) shut off the boiler fuel supply
d) close the main steam valve
e) ensure the glass is not leaking
A
If the safety valve on a boiler pops and the only pressure gauge indicates well below pop pressure, you would
a) notify the Boiler Inspector
b) reduce boiler pressure and get the gauge checked
c) shut down to fix the safety valve
d) increase spring pressure on safety valve
e) shut down the boiler and replace the safety valve and gauge glass
B
If the boiler safety valves open during boiler operation, you should
a) close the non-return valve on the boiler drum
b) shut the boiler down immediately
c) increase the forced draft flow to cool the boiler d) open the blowdown valves
e) reduce the fuel and air flow to the boiler
E
What causes the level in the gage glass to be higher than in the drum?
a) column drain valve leaking
b) steam valve on the gage glass closed
c) swell in boiler steam drum
d) starting up of the stand-by feedwater pump
e) guage glass steam and water valves are both open
B
What causes the level in the gauge glass to be lower than the water level in the boiler?
a) steam valve on the gauge glass closed
b) shrinkage in the boiler steam drum
c) drain valve on the gauge glass leaking
d) top try cock open
e) the steam pressure is excessively high
C
A firetube boiler furnace explosion
a) can be the result of too much scale on boiler tubes
b) is more disastrous than a pressure or waterside explosion
c) may be the result of oil in the water causing a foaming condition
d) may result from a flame scanner not working properly
e) could be caused by poor water circulation
D
A boiler pressure or waterside explosion
a) could be the result of water in the fuel oil
b) could be the result of inadequate ignition
c) may be caused by a low water condition
d) could result from improper sootblowing procedures
e) could be the result of broken refractory
C
A reason for many boiler accidents may be due to
a) inadequate training of operating personnel
b) log books being kept up to date and adequate
c) the regular testing and checking of control devices
d) not asking the insurance companies to inspect boilers more often
e) safety valves being oversized
A
The best method of ensuring adequate attention is being given to the boiler and its controlling and safety devices is to
a) schedule regular testing and checking procedures
b) maintain a log book showing testing results and by whom they were done
c) request staff to perform checks weekly
d) have faith in the personnel
e) always maintain good oral communication lines about tests and checks
B
Most furnace explosions occur
a) during the lighting up of a boiler burner
b) during the shutting down of a burner
c) during the purge period of lighting a boiler furnace
d) during the period of increasing the load
e) when steam pressure is excessive
A
The purging process for a furnace should be done
a) before each burner is lit
b) with the fuel valve closed
c) with the fuel valve in the open position
d) before the second burner is lit
e) with the pilot light on
B
Poor combustion due to the insufficient amount of __________ may cause a furnace explosion.
a) gas
b) fuel
c) heat
d) air
e) hydrocarbons
C
Failure to __________ the furnace thoroughly before light-up can cause a furnace explosion.
a) heat
b) drain
c) prime
d) cool
e) purge
E
Attempting to light a burner _______________________ may cause a furnace explosion.
a) from hot refractory
b) without preheating the fuel
c) without first cooling the fuel
d) without a pilot light
e) by pre-purging the furnace
A
Pressure explosions occur when a pressure part of the boiler such as the shell, furnace, or firetube bursts due to too high a steam pressure or a structural weakening of the metal. This weakening may be caused by:
1. corrosion
2. thermal stress
3. overheating
4. scale and sludge build-up
5. insufficient combustion air
a) 1, 3, 4, 5
b) 2, 3, 4, 5
c) 1, 2, 3, 4
d) 1, 2, 4, 5
e) 1, 2, 3, 5
C
Corrosion products in feedwater can cause
a) slag deposits in superheaters
b) decreased steam pressure
c) increased steam pressure
d) increase in boiler efficiency
e) tube failure
E
Cyclone separators are used to
a) separate water droplets from the steam
b) accelerate the steam leaving the boiler
c) heat the steam coming out of the drum
d) separate impurities from the water
e) separate water from the steam drum
A
A drum internal which acts to reduce thermal shock and turbulence is the
a) cyclone separator
b) drip-collector baffle
c) corrugated plate drier
d) internal feed pipe
e) chevron drier
D
Some smaller boilers have a pipe and baffle device in the steam drum which acts as
a) a separator
b) a chemical injection device
c) a scrubber
d) a drip collector baffle
e) an internal feed pipe
E
Chemicals are injected into the boiler to
a) prevent corrosion
b) keep sludge dispersed
c) prevent sludge
d) prevent scale
e) all the above
E
The chemical injection line is located
a) near the normal water level
b) close to the CBD line
c) in the steam space
d) near the internal feed pipe
e) close to the riser tubes
D
A "rule of thumb" rate of continuous blowdown is approximately
a) 10% of steaming rate
b) 5% of steaming rate
c) 15% of steaming rate
d) 1% of steaming rate
e) 3% of steaming rate
D
New refractory must be thoroughly and properly cured with a light fire because
a) of its high rate of differential expansion
b) it may burn if not cured
c) it may corrode if not cured
d) it contains moisture which can cause it to fracture if not cured
e) of the length of time it takes it to heat up
D
One cause of flame failure in oil or gas fired boilers is
a) excessive fuel temperature
b) fuel pressure being too high
c) the fuel being too volatile
d) water in the fuel
e) the hydrogen content is too low
D
If the main burner fails, this could cause
a) the steam atomizing pressure to increase
b) admission of unburned fuel to the furnace which may explode
c) the boiler efficiency to increase
d) the fuel valve to stay open
e) the pilot light to go out
B
Failure to __________ the furnace thoroughly before light-up can cause a furnace explosion.
a) heat
b) drain
c) prime
d) cool
e) purge
E
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