Power plant engineering

1. Unit 2- High Pressure
Boilers
Prepared by,
Mahesh Shahaji Pol
Lecturer, Government Polytechnic Karad

2. Contents
•Introduction
•Classification of Boilers
•High Pressure Boilers
•Fluidized Bed Combustion Boiler
•Classification & Need of FBC Boiler
•Arrangements and Control systems of FBC Boiler
•Comparison of High Pressure Boilers
•Indian Boiler Regulation Act
•Maintenance Procedure of High Pressure and FBC
Boiler

3. Learning Outcomes
The student will be able to,
• Explain with sketches the working of any type of High
Pressure Boiler.
• Compare the salient features of the any type of High
Pressure Boiler.
• Explain predictive and preventive maintenance of High
Pressure Boiler.

4. Introduction
•Definition:
According to Indian Boiler Regulation Act 2007, “Boiler is a closed
vessel in which steam is generated with capacity exceeding 25
liters, gauge pressure greater than or equal to 1kg/cm2 and water
is heated at temperature of 1000 c or above.
• Application
1. Power generating
2. Heating
3. Industrial Process

5. Classification of Boilers
• Fire tube boilers
• Water tube boilers
Relative position of
hot gases and water
• Vertical boilers
• Horizontal boilers
Geometric
orientation of boiler
• Internally fired boilers
• Externally fired boilers
Method of firing
• Low Pressure boilers
• High Pressure boilers
Pressure of steam
• Natural circulation boilers
• Forced circulation boilers
Method of
circulation of water
• Single tube boilers
• Multi tube boilers
Number of tubes in
boiler

6. High Pressure Boilers
• A boiler is called High Pressure Boilers when it operates with a
steam pressure above 80 bars. It is widely used in power generation
in thermal power plants.
• Examples: Lamont boiler, Benson boiler, Babcock and Wilcox boiler,
Velox boiler, Schmidt-Hartmann boiler.
• Features of High pressure boilers
1. Forced circulation of water
2. Large number of small diameter tubes
3. Higher steam pressure and temperature
4. Improved mode of heat transfer and heating
5. Pressurised combustion
6. Compactness and High efficiency

7. Lamont Boiler
•Water circulation maintained by
centrifugal pump.
•Generates approximately 30 to 45
tonnes of steam per hour at a
pressure of 150 bar and
temperature of 500 0 c.
•Advantages:
1. Small diameter tubes used so
high heat transfer rate is
maintained.
2. Multiple tube gives flexibility for
suitable location of heat transfer

8. Benson Boiler
• Difficulties of bubble formation is
eliminated.
•Transport is easy as no drum is
required & majority of parts carried
to site without pre assembly.
•Required small floor area.
•Superheater is integral part of
forced circulation system therefore
no special starting arrangement for
superheater is required.
•It has very little storage capacity
compared to drum type boiler.

9. Loeffler Boiler
•Difficulties of deposition
of salt and sediment is
eliminated.
•Most of the steam is
generated outside from
the feed water using part
of the superheated steam
coming out from the
boiler.
•Its generating capacity
of 94.5 tonnes/hour and
operating at 140 bar.

10. Schmidth-Hartmann
Boiler•In this boiler distilled
water is used for
generation of high
pressure steam which is
recalculated without any
wastage.
•Steam at 95-100 bar
pressure is generated in
the evaporating tube.
•It can use impure water
for generation of steam.

11. Velox Boiler
• It is compact and high combustion rates are possible as 35 to 45
million kJ per cubic meter of combustion chamber volume.
•Low excess air is required as the pressurized air is used and the
problem of draught is simplified.

12. Fluidized Bed Combustion
(FBC) Boiler
•Fluidization is method of mixing fuel and air in specific proportion for
obtaining combustion.
•Fluidized bed is the bed of solid particles behaving as a fluid.

13. Classification of Fluidized Bed
Combustion
Atmospheric fluidized Bed
Combustion (AFBC)
Bubbling
fluidized bed
combustors
Circulating
fluidized
Pressurized
fluidized Bed
Combustion (PFBC)
Classification of Fluidized Bed
Combustion

14. Need of FBC Boilers
• It can accept low calorific value fuels and relatively high moisture
fuels.
• In fluidized bed combustion, rapid mixing ensures uniformity of
temperature.
• Heat generation from municipal waste, sewage plant sludge,
biomass, agricultural waste and other high moisture for less pollution.
• To reduce boiler size.
• To reduce corrosion and erosion.

15. Arrangements of FBC
Boilers
Arrangements
of FBC
Fuel feeding
system
Air
distributor
Bed and In-
bed heat
transfer
surface
Ash
handling
system

16. Control Systems in FBC
Boilers
Control
Systems
Temperatur
e control
system
Pressure
control
system
Level
control
system
Flow
control
system

17. Advantages of FBC Boilers
• High thermal efficiency.
• Easy ash removal system, to be transferred for cement
manufacturing.
• Short commissioning and erection period.
• Safe operation and fully automated even at extreme temperature
conditions.
• Reduced coal crushing.
• Efficient operation at temperature down to 150 0 c.
• System can respond rapidly to changes in load demand.
• Operation at low temperature helps in reducing air pollution and
also reduces formation of nitrogen oxides.

18. Sr.
No.
Lamont
Boiler
Benson
Boiler
Loffler
Boiler
Schmidt-
Hartmann
Boiler
Velox
Boiler
1. Starting of
boiler is
quick.
Starting of
boiler is
slow.
Starting of
boiler is
quick.
Starting of
boiler is slow
than lamont
boiler.
Starting of
boiler is
less quick
than other.
2. Space
required is
less.
Space
required is
less.
Space
required is
more.
Space
required is
more.
Space
required is
more.
3. Internally
fired.
Internally
fired.
Internally
fired.
Externally
fired.
Internally
fired.
4. Vertical axis
boiler.
Vertical axis
boiler.
Horizontal
axis boiler.
Horizontal
axis boiler
Vertical
axis boiler.
Comparison of High Pressure
Boiler

19. Indian Boiler Regulation Act
•IBR is the law of India which was created in 15th September 1950 in
exercise of powers conferred by section 28 and 29.
•Regulation act 1920: It is an act of law. It governs the manufacture,
installation, operation and maintenance of steam boilers.
•To prevent hazard and explosions, some rules and regulations are
introduced as mandatory to follow by industrial sectors.
•In India, IBR act was established, which specified that, a Government
Inspector would be responsible and would have to certify all steam
boilers as suitable from safety point of view.
•In the IBR act, a steam boiler is defined as a vessel containing greater
than 22.5 liters of water, which is IBR boiler and IBR system.
•In this different conditions is given for repairing the boiler & boiler
component.

20. Maintenance Procedures of
High Pressure and FBC Boiler
• Check the Water Gauges
• Clean the Water Gauges
• Clean Piping and Float
Chamber
• Test the fuel Cutoff Feature
• Check Water Treatment
System
• Check Condensate Recovery
System
• Inspect for signs of Corrosion
and Leakage
• Check the Stack Temperature
Gauge
• Analyze Air to Fuel Ratio
• Clean Heat Transfer Surfaces
• Check and Maintain the
Economizer
• Update and Review Boiler Logs

21. Summary
In this content we have studied
• Classification of Boiler
• Different high pressure boilers
• Fluidized bed combustion boilers
• Classification of high pressure boilers
• Indian Boiler Regulation Act
• Maintenance procedures of high pressure and FBC
boiler.

22. Thank you.