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Boilers (A basic approach)
1. Contents:
1. Introduction
2. Boiler specifications and design
A basic approach
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2. Boiler specifications and design
3. Indian boiler regulation act
4. Basic boiler system
5. Classification of boiler
(a) Water tube boiler
(b) Fire tube boiler
(c) Packaged boiler
6. References Presented by:
Bhushith M Kumar
M.Tech in Energy systems
SJCE, Mysore
2. INTRODUCTION
๏ A boiler is a closed vessel in which water or
other fluids are heated.
๏ Steam Boilers are of very ancient origin. The introduction
of famous James Watt's improved steam engine from 1769
to 1775 onwards resulted in great improvement in steam
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to 1775 onwards resulted in great improvement in steam
plants.
๏ The fluid does not necessarily boil.
๏ Boilers can be found almost everywhere. A kettle, steam
locomotive, modern steam iron boxes etc are all examples
for boilers.
4. BOILER SPECIFICATION & DESIGN
๏ Specifications of a boiler are very much necessary in
order to have a better understanding of the optimum and
safe working parameters of a particular boiler.
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5. BOILER SPECIFICATION & DESIGN (cont)
๏ Modern boiler design offers several benefits. In the past,
improper design of boilers has caused explosions which
led to loss of life and property.
๏ Basic boiler design may be based upon the following:
๏ Production of a maximum quantity of steam with minimal
fuel consumption
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fuel consumption
๏ Economic feasibility of installation
๏ Minimal operator attention required during operation
๏ Capability for quick starting
๏ Quality of raw water: how hard or soft the water is will
determine the material of the boiler.
6. BOILER SPECIFICATION & DESIGN (cont)
๏ Capacity/steam output required, usually measured in
tonnes per hour or kg/s.
๏ Steam condition - pressure, temperature, etc.
๏ Safety considerations
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๏ Mechanical constraints
๏ Cost restrictions
๏ Monetary cost
๏ Tensile strength of material must be considered while
using any joining processes
7. BOILER SPECIFICATION & DESIGN (cont)
๏ Feed check valve: regulates the flow of water into the
boiler and prevents the back flow of water in case of
failure of the feed pump.
๏ Blow-off cock: removes water from the shell at regular
intervals to remove the various impurities that may be
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intervals to remove the various impurities that may be
settled at the bottom of the shell.
๏ Safety valves: automatically prevent the steam pressure
from exceeding safe levels
๏ Water-level indicators: indicate the level of water in the
shell
8. INDIAN BOILER REGULATION ACT
๏ In the year 1863, a very serious boiler explosion occurred
in Calcutta which caused the loss of several lives. As a
result of this explosion, the necessity of inspection of
boilers was widely recognized and a bill was introduced
in the Bengal Council to provide for the inspection of
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in the Bengal Council to provide for the inspection of
steam boilers. In the year 1864, the Bengal Act VI of 1864
was passed which provided for the inspection of steam
boilers and prime movers in the town and suburbs of
Calcutta. This is the beginning of boiler legislation in
India.
9. INDIAN BOILER REGULATION ACT (cont)
๏ The Indian Boilers (amendment) Act, 2007 which was
passed in December, 2007, has introduced improvements
in the provisions of the law to enhance safety norms, to
ensure uniformity in standards of inspection, expediting
inspections and reducing bureaucratic delays by
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inspections and reducing bureaucratic delays by
decentralization of inspection of boilers during their
manufacture, erection and use, by allowing inspection and
certification by the independent inspection authorities.
11. BASIC BOILER SYSTEM (cont)
๏ Heat sources:
๏ Coal is the standard fuel source for industrial boilers.
Most coal-boiler applications used pulverized coal (coal
ground to a fine powder), which burns more completely
than larger clumps of coal.
๏ Biomass fuel includes all types of burnable organic
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๏ Biomass fuel includes all types of burnable organic
material, including rice husk, wood chips, and other
agricultural waste products.
๏ Gas-fired boilers are designed to operate on either
propane or natural gas. Some gas-fired boilers can be
switched over to one or the other with some modifications
to account for the different characteristics of the fuels.
12. BASIC BOILER SYSTEM (cont)
๏ Gas-fired boilers are designed to operate on either
propane or natural gas. Some gas-fired boilers can be
switched over to one or the other with some
modifications to account for the different
characteristics of the fuels.
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๏ Oil-fired boilers used gasoline or other petroleum-
based fluids as the fuel source. Thermic fluid
heaters (described above) use these fluids as the heat
transfer medium.
๏ Wood is a fuel source used for some traditional
boiler designs.
13. BASIC BOILER SYSTEM (cont)
๏ Electric is used in the form of either resistance heating
coils or electrode-type units to provide heat for boilers,
typically those of very low capacities or those for
commercial/domestic use.
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14. BASIC BOILER SYSTEM (cont)
๏ The most fundamental decision when selecting a boiler is
what its function will be. Boilers can either be used to
produce hot water or produce steam.
๏ Hot water boilers are used to heat water for hot water
heating systems. Typical applications include domestic
and commercial hot water needs, comfort heating, freeze
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and commercial hot water needs, comfort heating, freeze
protection, commercial dishwashers, radiant floor heating,
car washes etc.
๏ Steam boilers heat hot water to boiling in order
to generate steam for use in different applications. These
include turbines for power generation, various industrial
heating applications (e.g. cement production), and
agricultural soil steaming.
15. CLASSIFICATION OF BOILERS
๏ Boilers can be distinguished based on their design
and construction, which defines their method of heat
exchange. They are of three types:
๏ Fire โ tube boilers
Water โ tube boilers
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๏ Water โ tube boilers
๏ Packaged boilers
17. CLASSIFICATION OF BOILERS (cont)
๏ Fire-tube boilers feed hot gases from the heating source
through tubes.
๏ These tubes are positioned inside a water filled drum in
order to transfer heat to the water.
๏ Fire-tube boilers are more fuel efficient and easier to
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๏ Fire-tube boilers are more fuel efficient and easier to
operate than water-tube boilers, and because of their
simple construction also tend to have a lower initial cost.
๏ However, because the thickness of the outer shell (which
contains and pressurizes the water) is limited by cost and
practicality, fire-tube boilers are typically limited to
low pressure and low to medium capacity applications.
20. CLASSIFICATION OF BOILERS (cont)
๏ Water-tube boilers feed water (rather than
combustion gases) through tubes.
๏ A large number of these tubes run through a boiler
drum (casing) where heated gases or heating
elements surrounding the tube bring the water to its
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elements surrounding the tube bring the water to its
boiling point. This heat transfer method makes
water-tube boilers more thermally efficient than fire-
tube boilers.
๏ These boilers are selected when steam demand and
steam pressure requirements are high.
21. CLASSIFICATION OF BOILERS (cont)
๏ However, they are more complex to construct and
are less tolerant of poor water quality, requiring
water treatment and/or solids filtering in order to
operate effectively.
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24. CLASSIFICATION OF BOILERS (cont)
๏ A package boiler or packaged boiler is a modern form
of steam boiler. They are factory-made to a range of
standard designs, according to the size and evaporative
capacity required.
๏ The advantages of a package boiler are that they are
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๏ The advantages of a package boiler are that they are
available 'off the shelf' without a lengthy design step and
also that they are simpler to install.
๏ The internal arrangement of a package boiler is usually a
one- or two-pass fire-tube boiler with an internal furnace
tube.
25. CLASSIFICATION OF BOILERS (cont)
๏ These use fuel-supplied burners that do not require
manual stoking, as solid fuels would.
๏ Burners use built-in electric fans to
provide draught through the burner. This encourages
mixing with combustion air, thus good burner
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mixing with combustion air, thus good burner
performance.
