Boiler Operation Flashcards
the number of pounds of steam generated per hour at the pressure and temperature required for all purposes to develop contract shaft horsepower of the ship divided by the number of boilers installed is defined as
boiler full power capacity
boiler overload capacity is normally what percentage of boiler full power capacity?
120%
a pressure specified by the boiler manufacturer as a criterion for the boiler design is termed as?
design pressure
what is the minimum steam drum pressure on an operating boiler?
85% of boiler operating pressure
what type of circulation would installing the generating tubes at an increased inclination be?
accelerated natural
what type of boiler conceits of one or more water drums?
drum type
do header type boilers have a water drum?
no
the term high pressure boiler refers to a boiler operating at what pressure?
751 psi or above
what two sheets of steel make up the construction of the steam drum?
wrappers sheet and tube sheet
what purpose do the generating tubes serve?
provide the area in which most of the saturated steam is generated
what is the function of the waterfall tubes?
to protect furnace refractories, and allow a higher heat release
water screen tubes protect the superheater from what?
direct radiant heat
what is installed between the inner and outer casings of the boiler to carry the downward flow of relatively cool water and thus maintain the boiler circulation?
downcomers
what portion of the steam drum contains a manhole to the drum for cleaning, inspecting and repair?
drumhead
which tubes of high firing rates do not generate steam?
downcomers
what boiler component preheats the feed water priors to its entering the steam drum?
economizer
what function do the metal projections on the economizer tubes serve?
to extend the heat transfer surface of the tubes
what is the heating source of the economizer?
combustion gases
what is the standard size of the firebrick?
2 1/2” x 4 1/2” x9”
insulating block is capable of withstanding surface temperature of?
1500 degrees F
what joins the boiler to the smoke pipe?
uptakes
refractory expansion joints are normally what size?
1/4”
what is the preferred material for expansion joints construction?
styrofoam
a boiler punge will have how many volumetric air changes?
five
a boiler must always be purged in accordance with what?
purge table
during a furnace inspection prior to light off the boiler inspection device (bid) fogs up, what is the probable cause?
presence of fuel oil in the furnace
can raw fuel be removed from the furnace by purging the boiler?
No, the fuel must be wiped up
once a boiler purge is complete, fires must be lighted within what time frame?
5 minutes
if ignition fails to occur within 2 to 3 seconds what action must be taken?
shut the burner fuel oil manifold valve, safety shutoff device and investigate the cause.
during a heaving black smoke condition the burner flame will be what color?
dark orange
an incandescent dazzling white burner flame is an indication of what?
excessive air
fuel oil temperature at the burner front shall not exceed what temperature?
125 degrees F
what is the function of the boiler sliding feet?
to allow for expansion and contraction of the boiler during light off and cool down
the steam generators separate the steam and water mixture by what action?
centrifugal action
the majority of the steam that leaves the superheater goes where?
main engines
a short term decrease in drum water level which results from a change in firing rate or steam flow without any corresponding change in the feeding rate is termed what?
shrink
the amount of heat is applied to steam to raise its temperature above the saturation temperature, while maintaining constant pressure is defined as?
superheat
what is the basic cause of all boiler explosions?
the accumulation of unburned fuel or combustion vapors at some point in the system
Steam soot blower elements add rotated at a rate of?
10 to 15 seconds per 90 degrees rotation
The minimum steam atomization temperature at the burner front is?
370 degrees F
The desired range of steam atomization temperature is?
400 degrees F plus or minus 10 degrees F
What prevents windmilling of an idle force draft blower, while the other force draft blower is online?
Automatic shutters
The chick facing of the sliding feet is constructed of what material?
Phosphorus bronze
What term is usually attributable to deficiency of air and excessive vibration of the boiler?
Panting
Heavy and prolonged seawater contamination of the fuel oil will from what type of corrosive products on the brick work?
Slag formation
What function does nichrome wire serve in the refractory?
As an anchoring device
A boiler that provides some means of controlling the degree of super heat independently of the rate of steAm generation is said to have?
Controlled superheat
Most modern naval boilers are designed for what type of circulation?
Accelerated natural circulation
What is the function of refractory materials?
To confine the heat to the firebox and protect the casing and structural members from overheating