Test 10: Boilers Flashcards
What chapter of the NSTM will you find the chapter on boilers?
Chapter 221
To what publication should you refer to find your ships boiler full-power capacity?
Manufacturers technical manual
Boiler overload is specified in the design of the boiler. Depending on its installation, boiler overload capacity is given either as the firing rate of the…
Steaming rate
The boiler overload capacity is usually what percentage of boiler full-power capacity?
120%
What term describes the actual pressure in the stream drum at any given time?
Steam drum pressure
The constant pressure at which the boiler is being operated is known as the…
Operating pressure
Which of the following statements defines the design pressure of a boiler?
The design pressure is specified by the boiler manufacturer as a criteria for boiler design.
The amount of Btu per pound of fuel absorbed by the water and steam divided by the Btu per pound of fuel is known as…
Boiler efficiency
If you were to state the efficiency of a boiler would you use:
A: 90%
B: 90: 1
C: 90 is equal to 1
A: 90%
The times during which the boiler has fires lighted for raising steam and the time during which it is generating steam is known as what?
Steaming hours
The total heating surface equals the sum of the generating, superheater, and economizer surfaces. You measure the total heating surface of a steam-generating unit on the side that is exposed to the…
Gases of combustion
At the maximum steam drum pressure point, what boiler safety valves lifts?
The first
Minimum steam drum pressure is usually what percentage of the boiler operating pressure?
85%
Naval boilers can be classified in several way. One way is to divide them into classes auxiliary boilers and what other class?
Propulsion boilers
Boilers can be classified according to their location relative to the fire and water spaces. In this type of classification, what class of boiler pertains to all propulsion spaces?
Water tube boilers
Boilers whose tubes slope steeply from the steam drum to the water drum will have what type of circulation?
Accelerated natural circulation
What factor determines the classification of natural-circulation water-tube boilers as either a header- or drum-type boiler?
The arrangement of the steam and water spaces
Name 2 statements for the description of a header?
It is a type of collection point and type of manifold
What is the only distinction between a header and a drum?
Size
For what reason are single furnace boilers known as D-type boilers?
The tubes form a shape that looks like the letter D
Because of the shape or arrangement of its tubes, a double furnace boiler is known as what type of boiler?
M-type
On most boilers superheater tubes are protected from radiant heat by what means?
Water screen tubes, which absorb the intense heat of the furnace
To be considered a high-pressure boiler, it must be operated at what minimum pressure?
751 PSI
What is the purpose of the steam drum located at the top of the boiler?
To receive feedwater and as a place where saturated steam is accumulated
On a steam drum, tube sheets are required to be thicker than the wrapper sheet for what reason?
To ensure adequate strength after the holes for the generating tubes are drilled.
The steam drum is located on the top of the boiler. Where are the water drums and headers located?
At the bottom of the boiler.
Which of the following are types of generating and circulating tubes?
Main generating tube tanks
Water wall and water screen tubes
Downcomers
What is the function of water wall tubes?
To protect the furnace refractories
A modern boiler contains approximately what number of tubes?
Between 1,000 and 2,000 tubes
In relation to the boiler, tube rows run in what sequence?
From the front to the rear of a boiler.
Which of the following is a source of information you can use to identify boiler tubes?
Boiler tube renewal sheet
Manufacturers’s tech manual
Boiler plans
H-shaped
T-shaped
U-shaped
W-shaped
Which one is used with convection-type vertical superheaters?
U-shaped
Used with convection type horizontal syperheaters
H, T, U, or W- shaped?
W-shaped
What boiler component uses heat from combustion gases to heat the feedwater before it enters the steam drum?
Econimizer
What is the purpose of the projections on the outer tube surface of an economizer?
To extend the heat transfer area of the tube
What are some factors that affect refractory service life?
Shock and vibration
Panting
Sustained high furnace temperature
To withstand shock and vibration, all areas of refractory must be anchored or held in place by one of three methods-by anchor strips, boiler tubes, and by what other method?
Brick bolts
Which of the following problems contributes to undue panting of a boiler?
Poor air-oil intermixture
Deficiency of air
Excessive oil temperature
In D-type burners, used in superheater cavities
Grade B Firebrick
Can only be used with specific burner types
Burner tile
It’s advantage is the speed and economy of insulation because handcuffing insulation or brick bolts is eliminated.
Castable insulation
Used primarily on studded tubes in divided furnace boilers.
Plastic Chrome Ore
Used as an insulation block and the casing in some boilers.
Insulating cement
When used, castable firelay refractory should be air-cured for what minimum period of time before it is baked out?
2 days
Which of the following types of refractory mortar develop(s) its strength after drying without being heated?
Class 1 & 2
Baffle tile is made from what material?
Silicon carbide
Styrofoam expansion joints must be cut to what uniform thickness?
1/5 inch
The majority of propulsion boilers have what total number of furnaces?
Three
What steam drum fitting disperses feedwater evenly in the steam drum?
Internal feed pipe
