2. What is a boiler?
• A boiler is a closed vessel in which water or
other fluid is heated. The heated or vaporized
fluid exits the boiler for use in various
processes or heating applications.
3. Construction of boiler
• Material- plain low carbon steel. U TS – 430 to 540 mn/m2.
• All flanged plating must be heated after flanging to 600
degree and then allowed to cool slowly in order to stress
relieve.
• Furnace are corrugated for strength, this arrangement also
gives more heating area as compared to plain furnace of
similar dimension.
• Manholes cut into the shell and or end plating must be
compensated by means of compensating ring,these being
riveted or welded in place.
4. USE OF STEAM ON SHIP
• Heating duties, M.E fuel oil heater,Purifier
heater, oil tank heating, Cargo heating, Air
conditioning and heating plant, Calorifier,
Gelley supply, Sea chests, tracing line for pipe
line heating.
• Run turbine Generator
• Run Cargo pump turbines in tanker
• Drive steam driven deck machinery like
Winches etc.
4
5. USE OF STEAM ON SHIP
• Operate bilge, Stripping and other steam
driven pump.
• Drive boiler feed water turbine.
• Evaporator/ Fresh water generator heating
media.
• Tank washing in tanker ship and general
cleaning.
5
6. USE OF STEAM ON SHIP
• For boiler soot blowing and for the steam
atomized burners.
• Fire fighting as used in steam smothering
system.
• Main Engine jacket F.W preheater and Lub oil
sump and drain tanks.
• Use in waste oil, Incinerator,slop tanks.
• Use as steam ejector media for ejector pump
and vacuum devices.
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7. Principle of heat transfer in boilers
• Radiation
• Conduction
• Convection
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8. Schematic Overview of a BoilerOpen Feed System
Boiler
•Carbonic acid
•Oxygen
•Scale
Condensate system
•Carbonic acid
•Oxygen
Feed system
•Carbonic acid
•Oxygen
Shore make up water
•Calcium
•Magnesium
•Silica
Blow down
•TDS
•Surface
•Bottom
9. Types of boilers
• Main Boiler- Propulsion of the vessel
• Auxiliary Boiler-Heating of heavy fuel oil using a steam heater,
necessary for propulsion would qualify the supplying boiler to be
referred to as an auxiliary boiler.
• Tank Boiler-A boiler with large water carrying capacity where the shell
is being used as the pressure vessel. Most low pressure auxiliary boilers
will come into this category.
• Exhaust Gas Boiler- Boiler operated by hot gas from engine or other
exhaust gas sources.
• Drum Type Boiler-Water tube boilers employing steam and water
drums. They are also known as bent tube type boilers.
• Package Boiler -Fully automatic, low capacity boilers packaged inside a
box type casing, capable of quick steam production and flexible in
being positioned anywhere; could be coil type or fire tube type.
C/E HANIF DEWAN 9
10. Classification of Boilers
Boilers can be classified as follows:
According to geometric orientation of boiler:
According to relative position of water and hot gases:
According to location of furnace:
According to method of water circulation:
According to working pressure:
According to mobility of boiler:
According to number of tubes in the boiler:
11. According to geometric orientation
of boiler
a) If the axis of boiler is horizontal then it is
called horizontal boiler. Example:- Lancashire
boiler, Locomotive boiler.
b) If the axis of boiler is vertical then it is called
vertical boiler. Example:- Cochran boiler.
c) If the axis of boiler is inclined then it is called
inclined boiler.
12. According to relative position of water
and hot gases
a) Fire tube boilers:- If the hot gases of
combustion from the furnace pass through
the tubes and water is surrounding the tubes
is called fire tube boilers. Example:- Cochran,
Lancashire, Locomotive.
b) Water tube boiler:- If the water passes
through the tubes and hot gases surrounding
the tubes is called water tube boiler.
Example:- Babcock and Wilcox boiler.
13. According to location of furnace
a) Externally fired boilers:- In this boiler the
furnace is placed outside the boiler shell.
Generally water tube boilers are externally
fired. Example:- Babcock and Wilcox boiler.
b) Internally fired boilers:- In this boiler the
furnace is placed inside the boiler shell.
Generally fire tube boilers are internally fired.
Example:- Lancashire, Cochran boiler.
14. According to method of water
circulation
a) Natural circulation boilers:- In this boiler, water
flow take place naturally, by density difference of
water. The flow of water and steam are set up
due to density difference resulting from
difference in temperature. Example:- Lancashire,
Babcock and Wilcox boiler.
b) Forced circulation boilers:- In this boiler, water
flow takes place by a pump. Example:- Benson
boiler, La- mont boiler, Velox boiler.
15. According to working pressure
a) High pressure boiler:- The working pressure of
this boiler is higher than 25 bar. Example:-
Babcock and Wilcox boiler.
b) Medium pressure boiler:- The range of working
pressure of this boiler is between 10 bar to 25
bar. Example:- Lancashire boiler, Locomotive
boiler.
c) Low pressure boiler:- The range of working
pressure is between 3.5 to 10 bar. Example:-
Cochran and Cornish boiler.
16. According to mobility of boiler
a) Stationary boiler:- This boiler cannot be
moved easily from one place to another
place. This are used in power generation or
process heating in industries. Example:-
Lancashire, Babcock and Wilcox boiler.
b) Mobile boiler:- It is portable boiler and can
be easily moved. This is used in marine and
locomotive. Example:- Locomotive boiler.
17. According to numbers of tubes in
the boiler
a) Single tube boiler:- This boiler having only
one fire or water tube for circulation of hot
gases or water. Example:- Cornish boiler.
b) Multi-tube boiler:- This boiler having two or
more fire or water tubes for the circulation of
hot gases or water. Example:- Locomotive,
Cochran, Lancashire, Babcock and Wilcox
boiler.
18. Smoke tube & Water tube boilers
18
Fire tube concept
Shell with fire tubes inside
Tank type boiler
Water tube concept
Drum with fire tubes
19. Water tube Boiler
• In a water tube boiler, boiler feed water flows through the tubes and enters the
boiler drum. The circulated water is heated by the combustion gases and
converted into steam at the vapour space in the drum. These boilers are selected
when the steam demand as well as steam pressure requirements are high .
• Most modern water tube boiler designs are within the capacity range 4,500 –
120,000 kg/hour of steam, at very high pressures. Many water tube boilers are of
pa kaged onstru tion if oil and /or gas are to e used as fuel. “olid fuel fired
water tube designs are available but packaged designs are less common.
• The features of water tube boilers are:
• Forced, induced and balanced draft provisions help to improve combustion
efficiency.
• Less totolerance for water quality, calls for water treatment plant.
• Higher thermal efficiency levels are possible
20. Comparison between Fire tube boiler
and Water tube boiler
Fire Tube Boiler
1) Hot gases are inside the tube and
water is outside.
2) Operating Pressure limited to 25 bar.
3) Rate of steam generation is lower.
4) Not suitable for large power plant.
5) Chance of explosion is less due to low
pressure.
6) Floor space requirement is more.
7) Cost is less.
8) Required less skill for efficient and
economic working.
9) For producing process steam.
10) There is no problem of scale
deposition and less problem of
overheating and bursting.
Water Tube Boiler
1) Water is inside the tube and hot gases
outside.
2) Can work under as high pressure as
more than 25 bar.
3) Rate of steam generation is higher.
4) Suitable for large power plant.
5) Chance of explosion is higher due to
high pressure.
6) Floor space requirement is less.
7) Cost is more.
8) Required more skill and careful
attention for efficient and economic
working.
9) For producing steam for power
generation as well as process heating.
10) Small deposition of scale will cause
overheating and bursting of the tubes.
23. Advantages of Cochran
Boiler
• It is compact and portable boiler therefore
minimum floor area is required.
• Initial cost of boiler is less.
• It can be moved and set up readily in different
locations.
• Quick and easy installation.
• Any type of fuel can be used.(coal or oil)
24. Disadvantages of Cochran
Boiler
• Steam raising capacity is less due to vertical
design.
• Water along with steam may enter the steam
pipe under heavy loads due to small steam
space.
• Efficiency is poor in smaller size.
25. Tank type & Drum type boilers
C/E HANIF DEWAN 25
Fire tube concept
Shell with fire tubes inside
Tank type boiler
Water tube concept
Drum with fire tubes
26. Type of Boilers
(BIB Cochran, 2003)
3. Packaged Boiler
Oil
Burner
To
Chimney
• Comes in complete
package
• Features
• High heat transfer
• Faster evaporation
• Good convective
heat transfer
• Good combustion
efficiency
• High thermal
efficiency
• Classified based on
number of passes
27. PACKAGED BOILER
• The packaged boiler is so called because it comes as a complete
package. Once delivered to a site, it requires only the steam, water
pipe work, fuel supply and electrical connections to be made to
become operational.
• Package boilers are generally of a shell type with a fire tube design
so as to achieve high heat transfer rates by both radiation and
convection.
• The features of packaged boilers are:
• Small combustion space and high heat release rate resulting in faster
evaporation.
• Large number of small diameter tubes leading to good convective heat
transfer.
• Forced or induced draft systems resulting in good combustion efficiency.
• Number of passes resulting in better overall heat transfer.
• Higher thermal efficiency levels compared with other boilers.
• This is a packaged boiler. More specifically, it is a typical 3 pass, oil
fired packaged boiler.
