This document discusses different types of high pressure boilers used in power plants. It begins by classifying boilers based on various criteria like contents, applications, axis, fuel type, pressure, and circulation. It then describes specific high pressure boilers like La-Mont, Benson, Loeffler, Schmidt-Hartmann, supercritical, supercharged and fluidized bed combustion boilers. For each type, it provides specifications, working principles, advantages and disadvantages. The document focuses on high pressure boilers used for power generation and their technical aspects.

1. Gujarat Power Engineering &
Research Institute
1
Power Plant Engineering
Prepared By:-
1)Patel Pranav V.(131040119042)
2) Patel Jigar B. (131040119032)
Guided By:-
Dr. Vijay K. Matawala
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2. High Pressure Boilers
The steam Generating Unit
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3. Rankine Cycle
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4. Purpose of Boilers:-
• For generating power in steam engines or steam turbines.
• In textile industries for sizing and bleaching.
• For heating the buildings in cold weather and for producing
hot water for hot water supply.
• In the Process industry like sugar, Fertilizers, Paper.
• Marine applications.
• Locomotives (it is now a day obsolete).
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5. Boiler Classification
 The boilers are classified based on the various criteria :
• Based on the contents of fluid :-
- Fire tube Boilers
- Water Tube Boilers
• Based on applications:-
- Utility Boilers
- Industrial Boilers
- Marine Boilers
- Locomotive Boilers
• Based on Axis :-
- Horizontal Boilers
- Vertical Boilers
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6. Continue...
• Based on the fuel :-
- Coal - Wood
- Gas - Diesel
• Based on the Pressure:-
- High Pressure Boilers (P > 80 bar).
- Medium Pressure Boilers (30 < P < 80 bar).
- Low Pressure Boilers (P < 30 bar).
• Based on Circulation of Water:-
- Natural Circulation
- Forced Circulation
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7. Circulation in boiler:
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8. Why the High Pressure Boiler ?
• Where 30 bar pressure & steam rate of 30 tones/hour is
required the fire tube boilers are preferred due to lower cost.
• In the power plant it is necessary to produce the steam at
high pressure , high rate and high efficiency.
• For the steam of 30 bar pressure & steam rate of 30
tones/hour is required then the water tube boilers are
preferred.
• Modern high pressure boilers are generate stem at the rate of
30 to 650 tones/hour and pressure upto 225 bar and temp. of
around 5500 C.
• To reduce the drum size.
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9. Advantages of High pressure Boilers
• Due to forced circulation of water, evaporative capacity of the
boiler is increased and size of drum is reduced.
• Due to high velocity of water, chances of scale formation is
reduced.
• Due to uniform heating there is less chances of overheating.
• High Temp. and Pressure increases the plant efficiency.
• The steam can be raised quickly to meet the variable load.
• It is using modified draught system which leads to reduction
in the pollution.
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10. Different High Pressure Boilers
• La-Mont Boiler
• Benson Boiler
• Velox Boiler
• Loffler Boiler
• Schmidt-Hartmann Boiler
• Supercritical Boiler
• Supercharged Boiler
• fluidized bed combustion Boiler
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11. La-Mont Boiler
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12. Specifications
• Pressure 120 bar .
• Temperature up to 5000 C or above.
• Steam production rate : 45 to 50 tones/hour.
12
Difficulties
• The deposition of salt and sediments on the inner surfaces of
the water tubes ,which reduces the heat transfer rate.
• There also formation of bubbling at the inner surfaces of
water tubes.
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13. Benson Boiler
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14. Specifications
• It was discovered based on the argument of “If the pressure
of boiler is raised to the critical pressure of (225 bar), the
steam and water have same density .”
• So, The danger of bubble formation can be easily eliminate.
• Temperature high up to 6500 C .
• Pressure 225 bar.
• Steam production rate : 150 tones/hour.
• Once through boiler.
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15. Advantages
• It does not require drum it leads to the overall weight up to
20% and also reduction in cost also.
• At the overload it can be operated economically by changing
pressure and temperature.
• There is no problem of bubbling.
• High steam generation rate. So, used for steam power plant.
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16. Disadvantages
• Salt deposition.
• Sediment on the inner surface of tube.
• Danger of over heating.
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17. Loeffler Boiler
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18. Specification
• Forced circulation.
• Pressure 100 bar.
• Steam production rate : 100 tones/hour.
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19. Working
• The steam circulating pump draws saturated steam from
evaporative drum.
• The steam passes through radiant and convective
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20. Schmidt-Hartmann Boiler
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21. Supercritical Boiler
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22. Continue...
22
• The most recent method to produce economical electric
power is by the use of supercritical boiler in the power plant.
• In the supercritical boiler working under the pressure above
critical pressure (221.2 bar), so the enthalpy of evaporation is
becomes zero. And at the temperature of 3740 C. and the
problems of bubbling is solved.
• The once through boiler is only type suited to supercritical
boiler.
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23. Advantages
• Heat transfer rates are very high.
• There is no drum, so it weight is reduced.
• There is no two phase mixture. So, there is erosion and
corrosion is minimised.
23
Disadvantages
• The high pressure and temperature restrict the use of it.
• The impurities remains in tubes after evaporation of water and
blocks the flow passages.
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24. Supercharged Boiler
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25. • When the combustion is carried out under high pressure in
the combustion chamber by supplying the compressed air
then rate of heat transfer is increased and heating surfaces
required is reduced.
• The high pressure & temperature exhaust gases from
combustion chamber are used to run the turbine. The work of
turbine is used to run compressor.
25
Continue...
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26. Advantages
• It requires the 20 to 30 % less heat transfer area.
• Rapid start is possible in this boiler.
• The part of turbine output can be used to run another
auxiliary of boiler.
Note:- it requires tight passage for high pressure gas.
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27. Fluidized bed combustion Boiler
• Fluidized bed combustion (FBC) is a combustion technology
used to burn solid fuels.
• In its most basic form, fuel particles are suspended in a hot,
bubbling fluidity bed of ash and other particulate materials
(sand, limestone etc.) through which jets of air are blown to
provide the oxygen required for combustion or gasification.
• The resultant fast and intimate mixing of gas and solids
promotes rapid heat transfer and chemical reactions within
the bed.
• FBC plants are capable of burning a variety of low-grade solid
fuels, including most types of coal and woody biomass, at high
efficiency and without the necessity for expensive fuel
preparation (e.g., pulverising).
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28. Principle of FBC
28
FLUE GASES
AIR IN
FEED WATER IN
DISTRIBUTOR PLATE
COAL +
DOLOMITE
STEAM
OUT
ASH
EVAPORATOR
TUBE
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29. Principle of FBC
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30. Advantages
• High thermal efficiency.
• Short commissioning and erection period.
• Efficient operation at temperatures down to 150° C ( i.e. well
below the ash fusion temperature).
• Reduced coal crushing etc. (pulverised coal is not a necessity
here).
• The system can respond rapidly to changes in load demand,
due to quick establishment of thermal equilibrium between
air and fuel particles in the bed.
• The operation of fluidized bed furnace at lower temperature
helps in reducing air pollution.
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31. Disadvantages
• There may be problem in distribution of coal and dolomite.
• The direct contact of flue gases and tubes may erosion.
• High pressure air is required.
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32. Types of FBC
• Atmospheric FBC
- Classical FBC
- Circulation FBC
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33. Classical FBC
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34. Advantages
• Production of NOx is temperature depended as in FBC
temperature is less than other combustion processes Hence it
results in low production of NOx.
• Lower production of SOx because SO2, SO3 etc. are captured
by limestone.
• FBC has 10 times more heat transfer then other combustion
processes because of burning particle, hence it has a high
combustion efficiency.
• FBC has a lower combustion temperature of 750 °C whereas
an ordinary boiler operates at 850 °C.
• Less area is required for FBC due to high coefficient of
convective heat transfer.
• Low air pollution. 3410/6/2016 Prepared By P.Vijaykumar Patel

35. Circulation FBC
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36. Circulation FBC
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37. Continue...
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38. Advantages
• Increase in bed residence time.
• High lateral turbulence.
• Effective burning.
• Comparative low pollution.
• Easy removal of Ash.
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