MARINE BOILERS
The following is a SELF EXAMINER questionnaire .
If you are marine engineer at sea, find out what you are worth.
At sea you are only respected for what you are worth! A donkey on a throne is still a donkey!!
Grading:
Correct- plus two marks
Wrong - minus one marks
Did not attempt- minus two marks
Time allowed- 50 minutes
If you score less than 20% marks -- you are NOT an engineer.
QUESTIONS:
1) The flash point of a residual fuel oil should be used to determine the highest temperature to which the oil may be heated
a)for atomizing
b)for centrifuging
c)in a storage tank
d)in the recirculating line
2)Oil or scale deposits on boiler tube walls will cause
a)those tubes to overheat
b)decreased boiler steam pressure
c)increased boiler steam pressure
d)an explosion in the boiler
3)Normally a boiler water sample should be taken
a)after the boiler has been blown down
b)before the boiler has been blown down or chemicals added
c)when the boiler has been refilled with makeup
d)from the highest point in the feed system
4)A lower than normal boiler stack gas temperature usually indicates
a)dirty firesides
b)dirty watersides
c)fuel high sulphur content
d)incomplete combustion
5)Boiler screen tubes are used to protect which of the listed components from high furnace temperature?
a)Superheater
b)Refractory
c)Wall tubes
d)Steam drum
6)Modern fuel oil temperature control devices are regulated to obtain a desired viscosity rather than a specific fuel oil temperature because
a)residual fuel oils have the same viscosity characteristics regardless of they are refined
b)the temperature of the fuel oil varies with the flow rate through the heater
c)the relationship between temperature and viscosity varies with different fuels
d)viscosity regulation eliminates the need for close control of the fuel/air ratio
7)The most harmful slag forming compounds found in fuel oils are
a)iron and sulphur
b)vanadium and sodium
c)potassium and nickel
d)calcium and silica
8)Which of the following procedures decreases the total dissolved solids concentration in the water of an auxiliary boiler?
a)Hydrazine treatment of condensate
b)Frequent compounding
c)Chemical cleaning
d)Bottom blowing
9)The purpose of the programmed purge cycle on an automatically fired auxiliary boiler is to
a)cool the furnace to prevent pre-ignition
b)remove explosive vapors from the furnace
c)evaporate accumulated unburned fuel oil
d)provide sufficient air in the furnace to allow ignition of the fuel
10)Automatic combustion control systems for some auxiliary boilers are designed to cycle burners on in response to
a)low fuel pressure
b)fuel return pressure
c)low steam pressure
d)furnace air pressure
11)When it becomes necessary to replace any tubes in a water-tube auxiliary boiler to eliminate leaks at the tube seats, the replacement tubes should be
a)stress relieved to ensure expansion when rolled
b)annealed to prevent cracking when rolled
c)fitted with a welded backing ring in the seat area
d)rolled, beaded, and seal welded around the bead edge
12)Which of the following items is necessary for all waste heat boiler installation, regardless of design or manufacturer?
a)Control of evaporation
b)A separate means to prevent feedwater contamination
c)Power circulating pump
d)Superheater
13)When a waste heat boiler is installed in the exhaust of a main position diesel engine, the exhaust gas bypass would be issued
a)at high loads to prevent overheating
b)at low loads to prevent corrosion in the boiler
c)during periods of high steam demand
d)when the turbocharger is in operation
14)The flame safeguard control system of a large automatic auxiliary boiler will provide fuel shut off in the case of high
a)water
b)voltage
c)fuel pressure
d)steam pressure
15)A feed pump for an auxiliary boiler might lose suction if the
a)boiler water level is low
b)feedwater is too hot
c)boiler steam demand is low
d)feedwater is too cold
16)Generating tubes in waste heat boilers are finned to
a)reduce gas flow turbulence
b)prevent exhaust gas corrosion
c)increase the rate of combustion
d)increase the rate of heat transfer
17)Combustion control systems on automatic boilers are designed to prevent immediate burner ignition after a normal or safety shutdown in order to allow time for
a)the furnace to be purged
b)electric charge buildup in the igniter
c)the fuel pump to start
d)the drum level to equalize
18) Dissolved oxygen can be removed from the boiler water by
a)frequent surface and bottom blows
b)dumping and refilling the boiler weekly
c)passing the water through absorbent filters
d)treating the water with chemical scavengers
19)A continuous blow is used to
a)regulate the density or salinity of boiler water
b)remove scum from the surface of boiler water
c)permit air to excapewhile raising steam in a cold boiler
d)remove sludge from the bottom of the water drum
20)A photoelectric cell installed in an automatically fired auxiliary boiler burner management system
a)opens the burner circuit upon sensing a flame failure
b)detects a flame failure by monitoring radiant heat from glowing refractory
c)requires mechanical linkage to secure the burner fuel supply
d)must be bypassed at low firing rates
21)The end product of reactions occurring when boiler water is chemically treated, remain in the boiler and increase the need for
a)acid cleaning
b)makeup feed
c)boiler blowdown
d)waterside corrosion treatment
22)When the flame scanner senses flame failure during boiler operation, which of the listed events will occur FIRST?
a)The fuel oil service pump is stopped.
b)The automatic purge cycle commences.
c)The fuel oil solenoid valve is de-energized.
d)The "trial for ignition" period commences.
23)As the percentage of CO in the stack gas decreases, you can assume that
a)the fuel to air ratio is increasing
b)fuel is being burned with increasing economy
c)you are approaching secondary combustion
d)excess air is increasing
24)Which of the listed types of strainers are installed between the fuel oil heater and the burner manifold?
a)Duplex
b)Magnetic
c)Simplex
d)Self-cleaning
25)The greatest deterrent to heat transfer from the fireside to the waterside of a boiler is
a)water film
b)water eddies
c)gas film
d)gas eddies
26)High stack temperature occurring in an auxiliary boiler could be a result of
a)insufficient air for combustion
b)complete combustion in the furnace
c)secondary combustion in the uptake
d)high fuel oil temperature
27)Oxygen corrosion in auxiliary boilers is prevented by treating the boiler feed tank with either sodium
a)sulfite or hydrazine
b)sulfite or hygroscopic sulfite
c)bromide or hydrazine
d)bromide or hygroscopic sulfite
28)Radial cracks have developed in the castable refractory of the burner cones after the first firing since the installation of new furnace front refractory. This is an indication of
a)a need for plastic firebrick patchwork
b)inadequate cone angle
c)a need for castable refractory patchwork
d)relieved stresses
29)In most marine boilers, the primary reason the first few rows of generating tubes, called screen or furnace row tubes, are made larger than the rest of the generating tubes is because
a)they require more water flow since they are exposed to the greatest heat
b)they must screen the superheater from the direct radiant heat of the burners
c)they must act as downcomers to ensure proper circulation
d)their main function is to retard combustion gas flow for maximum heat transfer rates
30)Boiler efficiency and its ability to absorb heat is limited by the need to
a)maintain an excess of CO during transient firing rates
b)prevent excess air density at low load conditions
c)protect the safety valves from excessive temperature
d)maintain uptake gas temperature above the dew point
31)Panting in an oil fired marine boiler can be caused by
a)excessive combustion air supply
b)low fuel oil temperature
c)fouled burner sprayer plates
d)insufficient combustion air supply
32)The MOST common cause of heat blisters developing on boiler generating tubes is due to
a)waterside deposits
b)fireside deposits
c)low water level
d)insufficient water circulation
33)While the vessel is rolling in heavy seas, the level in the boiler gage glass remains steady, this is an indication of
a)the gage glass is functioning normally
b)there is most likely an obstruction in the lower valve
c)the steam drum is adequately baffled
d)the water level in the steam drum is too low
34)Oil deposits can be removed from the waterside of boilers by "boiling out" with a/an
a)alkaline solution
b)acid solution
c)salt solution
d)kerosine solution
35)Oxygen content of boiler feed water at 50C is –
a)same as water at 90C
b)twice more than water at 90C
c)thrice more than water at 90C
d)4 times more than water at 90C
36)In a boiler furnace, which statement is true
a)the waterwall protects the refractory
b)the refractory protects the water wall
c)where there is refractory there is no waterwall
d)none of above is true.
37)The purpose of a superheater in a boiler is
a)to get more steam as steam is in contact with water
b)to get higher pressure steam
c)to get more heat on steam at lower pressures
d)to get wet steam
38)The bottom blow to remove solid matter ( not salinity ) of boiler is done by
a)one short blow with boiler running
b)one long blow with boiler cut off
c)several short blows when boiler is cut off
d)several short blows with boiler running.
39)On a chemical tanker discharging palm oils in Baltic in winter, some palm oil traces are found in the hotwell. This will cause –
a)foaming in the boiler
b)fluctuating water level in drum
c)wet steam on deck
d)all of above
40)Excellent combustion in a boiler furnace is indicated by , the % of gases in funnel stack as follows
a)CO/ Zero %
b)CO2/ 14%
c)oxygen/ 5%
d)all of above
41)A boiler safety valve which has popped several times in succession—
a)will have same popping pressure
b)popping pressure will become progressively higher
c)popping pressure will become progressively lower
d)lower first and then higher
42)What when present in boiler feed water causes scaling
a)sodium carbonate
b)sodium suphate
c)calcium sulphate
d)hydrazine
43)Impurities in boiler feed water causes-
a)scale formation
b)corrosion
c)water carry over
d)all of above
44)Water carry over in boiler steam can be caused by
a)high concentration of dissolved solids
b)high alkalinity of feed water
c)high concentration of suspended solids
d)all of above
45)If oil enters the boiler, it will coat the
a)top tubes
b)bottom tubes
c)both top and bottom
d)middle tubes
46)The boiler superheater safety valve is set at
a)higher pressure than the drum safety valve
b)lower pressure than the drum safety valve
c)same pressure
d)can be higher or lower
47)the purpose of a water wall in a boiler is to—
a)it increases the boiler capacity
b)it reduces maintenance to the refractory
c)it increases heating surface
d)all of above
48)What are the causes of refractory failure in a boiler
a)warming up of boiler too quickly
b)leaving air register open when the flame is cut out
c)failure to repair cracks when inspecting furnace
d)all of above
49)Carbon on the atomizer tip of a boiler is not indicated by -
a)low fuel oil temperature
b)low fuel oil pressure
c)cold air
d)diffuser plate out of place
50)Adding Hydrazine hydrate N2H2 to boiler water
a)removes oxygen
b)makes iron oxide sludge non adherent
c)increases alkalinity
d)all of above
51.After closing the drain during the blowing procedure for a glass water gauge, the water cock is opened and the water flows to the top of the glass. Then the steam cock is opened and the water flows down and out of the glass; Which of the following statements are correct?
The water level is between the water cock connection of the boiler, and the bottom of the gauge glass. It is safe to put feed water into the boiler.
The water level in the boiler is below the water cock connection of the boiler. It is unsafe to put feed water into the boiler.
The water level is above the steam cock connection of the boiler. There is a danger of priming the boiler if any additional feed is put into it.
The water level is normal, but it requires time for the gauge glass to stabilise. It is safe to put feed water into the boiler.
52.Feed check valves for main and auxilliary purposes are normally of the double shut off type, as shown in the diagram. What is the main function of the non-return valve?
To prevent the steam and water in the boiler from discharging out by the feed line, if a feed line fracture or a joint in the line blows.
To allow overhaul of the screw down valve when the non-return valve is shut and the boiler is steaming.
To increase the workload for staff when overhauling the boiler.
To allow fine tuning of feed water flow to the boiler.
53.If inspection or repair of the boiler is due, the plant has to be shut down, and the boiler emptied for water. If time is available, which of the following procedures are correct?
The boiler be blown down to sea immediately after shut down.
The boiler be allowed to cool down by its own after shut down. Then pump the water out.
The feed water regulator to be bypassed and the boiler topped up with cold feed water immediately after shut down.
The safety valve easing gear be operated and all the pressure released immediately after shut down.
54.Classification societies require that when initially fitted to a boiler, safety valves must be subjected to a test of accumulation of pressure. Is this to:
See how high the boiler pressure will go before the safety valve operates.
See at what pressure the safety valve will reset.
Ensure the valves are of the correct discharge capacity for the boiler.
Ensure the maximum firing rate can keep the pressure above normal working pressure
55.The principal objects for boiler feed water treatment should be:
Prevention of corrosion in the boiler and feed water system by maintaining the boiler water in an alkaline condition and free from dissolved gases.
Control of the sludge formation and prevention of carry over with the steam.
Prevention of scale formation in the boiler and feed water system by (a) using distilled water or (b) precipitating all scale forming salts into a non-adherent sludge.
All of the mentioned reasons.
56.The boiler have been shut down completely for inspection and repair. You have finished work and are going to start firing the boiler. What is the correct procedure for heating a boiler from cold?
Start the firing on maximum rate and raise the pressure in as short a period as possible, to save energy.
Start the firing on minimum rate and alternate with maximum rate continuously firing until the boiler is up to pressure.
Start the firing on minimum rate and continuously fire until boiler is up to pressure.
Start with intermittent firing, using small firing periods and long intervals gradually building up to longer firing periods and shorter intervals.
57.After obtaining permission from the duty Deck Officer, under what conditions would the process of soot blowing the boiler tubes be most beneficial?
When the boiler is firing on high rate.
When the boiler is firing on low rate.
When the boiler is firing on medium rate.
When the boiler is standing idle.
58.Which of the following is not a principle of heat transfer utilised in a boiler?
Convection.
Conduction.
Ionisation.
Radiation.
59.Low temperature corrosion can occur in both oil fired and exhaust/waste heat recovery boilers. Considering a fuel with same sulphur content, the air/fuel number,lamda, in a combustion process also indicates a relation to what temperature sulphuric acid condensates. What is the correct relation between air/fuel ratio and low temperature corrosion?
High air/fuel ratio rises the condensation temperature, and thereby reducing the safe limits between normal operation and condensation temperature.
High air/fuel ratio rises the air speed and thereby lowers the pressure and temperature so sulphur acid condensates.
High air/fuel ratio does not contribute significant to change of condensation temperature.
High air/fuel ratio lowers the boiler temperature causing the sulphur acid to condensate.
60.An expansion process along a turbine venturi is ofthen recognized as if no heat transfer out of the system is occuring What is the correct term for this?
.
Isochorie.
Adiabatic.
Isobar.
Endothermic
61.Most boiler design incorporate external "downcomers". For what purpose are those "downcomers" primarely incorporated?
To increase heating surface area.
Ensure adequate circulation in all conditions of steaming.
Provide extra support for furnace tubes.
None of above
62.For what purpose is a "de-aerator" in a boiler feed water system used?
Removal of excess nitrogen in the feed water.
Removal of excess sulphur in the feed water.
Removal of excess hydrogen in the feed water
Removal of excess oxygen in the feed water.
63.Waste heat recovery is important to save energy. By using the hot exhaust gases from main and auxiliary engines, the energy is transferred to the steam system by the waste heat boiler. Low output from engines, and low funnel temperatures can make area finned surfaces. What kind of acid would be present?
Sulphuric acid.
Hydrochloric acid.
Nitric acid.
Ascorpic acid.
64.Fluctuation of high temperatures under flame impingement, makes the surface of the firebrick breaking away in layers. What is the correct engineer term for this?
Spewing.
Slopping.
Slagging.
Shrinking.
65.Which of the below statements characterizes the most significant differences between a water-tube boiler and a fire-tube boiler during operation?
The watertube boiler can tolerate a short period of time without any water, when the oilburner is still in action.
Water-tube boilers are more efficient and contains less water. They suffer from major damages when run dry during operation.
The firetube boiler does not need any non-return valves in the feedwater line circuit.
The firetube boiler has a much better capability to work at higher steam pressure.
66.Quality of the feed water in a steam plant changes during operation. Caused by this, the water is regularly tested. Which of the below statements describes the chemical mechanisms normally occuring?
Generation of carbonic acid causes the water quality to drift towards sour and lower the pH - number.
Generation of sulphur acid causes the water quality to drift towards sweet and rise the pH - number.
All of the mentioned alternatives.
Water is becoming sligthly less conductive and does not transfer heat.
67.You are going to start firing a boiler. Which of the below mentioned alternatives do you consider as most important?
Opening the main steam pressure outlet valve.
Activating the main safety valves.
Bottom-blowing the boiler to be absolutely convinced that water is present in the boiler.
None of the above
68.Which feedwater condition would you prefer?
pH value 7.5
Rich on H2 C5 OH
Rich on oxygen.
Slightly salt.
69.What is the main purpose of bottom-blowing a boiler?
To control that water is present in the water chamber, when the boiler is in active operation.
To adjust steam pressure when the burner capacity is excessive.
To check that we do not have any leak of smoke and gases in the combustion camber.
To get rid of sludge in the water chamber
70.What is an effective means of measuring total dissolved solids in boiler water?
Conductivity test.
Alkalinity test.
Chloride test.
Not possible to test solids in boiler water.
71.What initial simple recommendation can we give to reduce oxygen in the boiler water?
Lower the feed water temperature.
Increase the boiler pressure.
Increase the "Blow down".
Raise the feed water temperature.
72.What is the correct PH-value for the Boiler Water?
8,3 - 9.
4,5 - 6.
Below 4,5
9 - 11.
73.What will you do if the PH-value in the boiler water is over 11?
Increase the dosage of chemicals.
Decrease the dosage of chemicals.
Blow the boiler and renew water until the PH-value is normal again
Nothing.
74.Which of the below listed effects can be caused by the presence of Calcium in the boiler water?
Loss of alkalinity, corrosion of boiler metal surfaces, and loss of phosphate reserve in the boiler.
Passifying of boiler metal surfaces.
Increase of alkalinity and PH-value.
No negative effects.
75.For a low pressure boiler, after testing the water cloride level, it is found to be 500 PPM, what action would you take?
Blow down boiler and check condenser for leakage.
Do nothing.
Decrease dosage.
Increase dosage.
76.If oil is found in the boiler water, what action would you take other than isolating the leak?
Dose with coagulent and blow down the boiler.
Blow down the boiler.
Do nothing.
Dose with coagulent.
77.At what interval should boiler water testing usually take place?
Every month
Every watch
Every day.
Every 3 months
78.In a low pressure auxiliary boiler, what would you consider to be the maximum allowable chloride level?
300 PPM.
2 PPM
3 PPM
18 PPM
79.In a low pressure auxiliary boiler, what would you consider to be the normal operating range of phenolphthalein alkalinity ?
100 - 300 PPM CaCO3.
2- 8 PPM
0.5 -2 PPM
8- 25 PPM
80 Testing feed and main boiler water condition and adjusting water treatment must be done , as per class rules —
a)every 4 hourly watch
b)once a month
c)once a week
d)every 24 hrs
81 Boiler water reading records shall be available on board ,as per class rules of –
a)chlorides/ phosphates
b)pH
c)Oxygen
d)All above
82 Common chemicals used to prevent formation of boiler tube scales are
a)calcium phosphate
b)magnesium hydroxide
c)sodium chloride
d)sodium phosphate
83 Thermal deaeriation in cascade tank/ hotwell removes dissolved oxygen up to—
a)10%
b)50%
c)95%
d)75%
84 Oxygen remaining after thermal deaeration is removed by chemical scavenging using
a)Hydrazine
b)sodium phosphate
c)sodium hydroxide
d)caustic soda
85 Sodium sulpite chemically combines with oxygen to form—
a)Nil dissolved solids
b) dissolved salts
c)nitrogen
d)none of above
86 Hydrazine causes—
a)cancer
b)tuberculosis
c)asthma
d)safe for use
87 Water / steam side of boiler is passivated at pH
a)3.5 to 5
b)10 to 11
c)13 to 14
d)7
88 Alkaline water changes from pink to colourless phenolphethelein at
a)8.3
b)12.9
c)1.8
d)2.9
89 Boiler water is tested for correct alkalinity to—
a)precipitate hardness salts to prevent scale
b)passivate with Fe3O4 film
c)maintain silica in solution to prevent scale
d)all above
90 Feed water and condensate pH value should be—
a)11 to 12.1
b)8.3 to 9
c)7 to 7.3
d)6.4 to 7.6
91 Boiler water pH should be in the range of
a)8 to 8.9
b)9.5 to 11
c)3.4 to 5.8
d)13 to 13.2
92 Cooling fresh water pH value should be-
a)8.3 to 10
b)12 to 13.1
c)5.2 to 7.1
d)7
93 Boiler feed water chloride value should be less than
a)0.249 ppm
b)3 ppm
c)15 ppm
d) 200 ppm.
94 Cooling fresh water ppm for chlorides should be max—
a)50
b)300
c)3
4)0.249
95 Hydrazine does the following—
a)scavenged dissolved oxygen
b)reduced red oxide to black oxide
c)raises the pH of condensate and feed water systems
d)all of above
96 Boiler feedwater testing is for—
a)hardness
b)oxygen
c)chlorides
d)all above
97 Factors affecting boiler water tube corrosion are
a)cavitation
b)dissolved solids gases
c)micro organisms
d)all of above
98 Condensate testing is for
a)pH
b)chlorides
c)ammonia
d)all above
99 The main purpose of boiler water treatment is to—
a)reduce hardness
b)increase pH
c)remove oxygen
d)all of above
7B
8D
9B
10C
11D
12A
13B
14D
15B
16D
17A
18D
19A
20A
21C
22C
23D
24A
25C
26C
27A
28D
29A
30D
31D
32A
33B
34A
35D
36A
37C
38C
39D
40D
41C
42C
43D
44D
45B
46B
47D
48D
49D
50D
51A
52A
53B
54C
55A
56D
57A
58C
59A
60B
61B
62D
63A
64C
65B
66A
67A
68A
69A
70A
71D
72A
73C
74A
75A
76A
77C
78A
79A
80D
81D
82D
83A
84B
85A
86B
87A
88D
89B
90B
91A
92C
93A
94D
95D
96D
97D
98D
99D
CAPT AJIT VADAKAYIL
29 YEARS IN COMMAND
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