Main Propulsion Boilers And Fittings Flashcards
What are the two main components of an oil burner?
The atomizer assembly and the air register assembly
What is the purpose of the atomizer?
Divides the fuel oil into fine particles for combustion
What is the purpose of the air register?
The air register admits combustion air to the furnace and helps mix the air and fuel oil spray
What function does the safety shutoff device serve?
Prevents oil spillage when an atomizer assembly is removed from a burner while the burner root valve is open
What are the two types of atomizer used with main propulsion boilers?
Mechanical and steam atomizers
What are the five advantages of steam atomization?
High turndown ratio Cleaner burning of residual fuel Less fireside deposits Better combustion in a cold furnace Wilder range at lower pressures
How must atomizer sprayer plates be stored?
In their storage tray with a light coat of lubricating oil applied to prevent corrosion
How long must the atomizer barrel be cooled after removal from the burner assembly before disassembly?
15 minutes
How are atomizer sprayer plate orifices checked for proper size?
With a GO/NO-GO gage
What is used to clean atomizer sprayer plates?
Wood cleaning sticks
Who shall make frequent inspections to ensure that sprayer plates and nozzles are in good condition?
Engineering officer
What is the normal dismantling period to rebuild a safety shutout device?
Every 1800 hours
What are the two principal parts of an air register?
The diffuser and the air foils
What is the purpose of the diffuser?
The diffuser provides primary mixing of the fuel droplets with air and prevents blowing the flame away from the atomizer
What are the two types of safety valves used?
Huddling chamber
Nozzle reaction
What causes the initial lifting of a safety valve?
Static pressure
On a nozzle reactions safety valve the guide ring has what function?
To control blowdown
What is the function of the nozzle ring on a nozzle reaction safety valve?
To control the sharpness of the valve opening and closing
Safety valves installed on 1200 psig boilers have a lifting pressure tolerance of what?
Tolerance plus or minus 10 psig
All safety valves installed onboard have a blowdown range of what?
Between 3 and 6 percent
When shall safety valve gages be placed on the boiler prior to setting safeties?
When the steam drum pressure is 100 to 200 psi below the lowest safety valve setting, or 75 percent of working pressure, whichever is higher
What is the lifting tolerance for safety valves installed on 600 psig boilers?
Plus or minus 5 psig
If the safety valves of any boiler cannot be adjusted to lift within the prescribed range, what action must be taken?
The boiler shall not be used for steaming until the fault has been corrected
All safety valves of each boiler shall be tested annually in accordance with what guidelines?
Those guidelines as established by the planned maintenance system
what must be done when safety valves are accidentally lifted by water during boiler hydrostatic testing?
they shall be tested to ensure proper operation
soot blowers now in service may be classified into what general types?
rotary and stationary
the accumulation of heavy fireside deposits can be significantly reduced by what?
frequent use of soot blowers
what are the three reasons that soot must be removed from a boiler?
to prevent fires
to mainrain excellent heat transfer rates
to prevent the formation of sulfuric acid which occurs when soot and moisture combine
what is the reason for operating the soot blowers in a proper sequence?
to sweep soot toward the uptakes
what is the only authority that can approve the blanking of soot blowers?
NAVSEA
what is the purpose of the scavenging air system receive its air source?
the boiler air casing
what is the purpose of the bilge drain valve in the soot blowing piping system?
to maintain continuous drainage of the system
what is the purpose of the scavenging air connection located on the soot blower head
supplies air to the soot blower element to prevent the combustion gases from backing up into the soot blower head or the steam piping
how is continuous drainage of the soot blower piping system accomplished?
by means of internal hole drilled in the body or seat of the bilge drain valve
what is the size of the internal drain hole on the soot blower drain valve on 1200 psig systems?
1/16 inch
what is the bilge drain hole size on soot blower systems that operate at 600 psig or below?
1/8 inch
soot blower piping systems must be warmed up sufficiently to prevent what?
piping failure
what is the purpose of the nozzles on the soot blower element?
to direct the jets of steam so that they sweep around the tubes, thus preventing direct impingement
what is the purpose of the cams on the soot blower head?
to control the blowing arc of the soot blower element
a broken mica on the gage glass must be replaced at first opportunity to prevent what?
rapid fogging of the glass
gage glass in stowage shall be kept out of contact with what?
iron or steel to prevent the scratching of the finely polished glass
why must a predetermined tightening sequence be used when tightening the gage glass studs?
to provide a uniform compression on the sealing surfaces to prevent leakage
why is a ball check valve installed in the bottom cutout valve of the gage glass?
prevents the escape of hot water in case the gage glass breaks
over tightening of the gage glass studs can have what detrimental effect?
cracking of the cone washers
what is installed on the boiler to allow the operators to observe the water level from their watch stations?
remote water level indicators
the majority of ships have two remote water level indicators that are designed in what manner?
primary and secondary
the primary water level indicator activates the high and low water alarms and generates an electrical signal that is proportional to what?
water level
smoke periscopes are fitted on naval boilers for what reason?
to observe the quality of the combustion gases passing through the uptakes
if mercury filled thermometers are being used in the fire room, what action must be taken?
they must be removed and replaced when possible
where can specific information be found concerning pressure ages and thermometers?
NSTM Chap 504
what is the purpose of the boiler internal feed water pipe?
to distribute feed water evenly throughout the steam drum
the first stage in the separation of steam and water in a CE boiler is accomplished by what?
primary separators
what component separates the steam and water mixture by a series of a corrugated plates that create rapid changes in direction?
seconddary separators
where is the desuperheater normally located?
either the steam drum or water drum
what is the purpose of the desuperheater?
to reduce the temperature of a portion of the superheated steam to be used in auxiliary steam systems
what is the function of the dry pipe in the steam drum?
this is where the final separation of steam and moisture occurs, which is accomplished by one quick rapid change in direction
what purpose does the vortex eliminator serve in the steam drum?
reduces the swirling motion of the water as it enters the down comers
what is the purpose of the boiler air cock valves?
the air cock allows air to escape when the boiler is being filled and when steam is first forming; it also allows air to enter the steam drum when the boiler is being emptied
what is meant by the term stop check valve
the valve has two functions a feed stop valve or as check valve, depending on the position of the valve stem
what is the frequency of blowing tubes on a steaming boiler?
at least every 168 steaming hours
prior to entering port
after leaving port
as soon as possible after a heavy black smoke condition
the surface blow pipe in the steam drum has what function?
when the surface blow valve is open, this pipe carries off scum and foam fro the surface of the water in the drum
