Contents:1. Introduction2. Boiler specifications and design

A basic approach

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2. Boiler specifications and design3. Indian boiler regulation act4. Basic boiler system5. Classification of boiler

(a) Water tube boiler(b) Fire tube boiler(c) Packaged boiler

6. References Presented by:Bhushith M KumarM.Tech in Energy systemsSJCE, Mysore

INTRODUCTION

A boiler is a closed vessel in which water orother fluids are heated.

Steam Boilers are of very ancient origin. The introductionof famous James Watt's improved steam engine from 1769to 1775 onwards resulted in great improvement in steam

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to 1775 onwards resulted in great improvement in steamplants.

The fluid does not necessarily boil.

Boilers can be found almost everywhere. A kettle, steamlocomotive, modern steam iron boxes etc are all examplesfor boilers.

INTRODUCTION (contd.)

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BOILER SPECIFICATION & DESIGN

Specifications of a boiler are very much necessary inorder to have a better understanding of the optimum andsafe working parameters of a particular boiler.

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BOILER SPECIFICATION & DESIGN (cont)

Modern boiler design offers several benefits. In the past,improper design of boilers has caused explosions whichled 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.

BOILER SPECIFICATION & DESIGN (cont)

Capacity/steam output required, usually measured intonnes 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 whileusing any joining processes

BOILER SPECIFICATION & DESIGN (cont)

Feed check valve: regulates the flow of water into theboiler and prevents the back flow of water in case offailure of the feed pump.

Blow-off cock: removes water from the shell at regularintervals to remove the various impurities that may be

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intervals to remove the various impurities that may besettled at the bottom of the shell.

Safety valves: automatically prevent the steam pressurefrom exceeding safe levels

Water-level indicators: indicate the level of water in theshell

INDIAN BOILER REGULATION ACT

In the year 1863, a very serious boiler explosion occurredin Calcutta which caused the loss of several lives. As aresult of this explosion, the necessity of inspection ofboilers was widely recognized and a bill was introducedin the Bengal Council to provide for the inspection of

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in the Bengal Council to provide for the inspection ofsteam boilers. In the year 1864, the Bengal Act VI of 1864was passed which provided for the inspection of steamboilers and prime movers in the town and suburbs ofCalcutta. This is the beginning of boiler legislation inIndia.

INDIAN BOILER REGULATION ACT (cont)

The Indian Boilers (amendment) Act, 2007 which waspassed in December, 2007, has introduced improvementsin the provisions of the law to enhance safety norms, toensure uniformity in standards of inspection, expeditinginspections and reducing bureaucratic delays by

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inspections and reducing bureaucratic delays bydecentralization of inspection of boilers during theirmanufacture, erection and use, by allowing inspection andcertification by the independent inspection authorities.

BASIC BOILER SYSTEM

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BASIC BOILER SYSTEM (cont)

Heat sources: Coal is the standard fuel source for industrial boilers.

Most coal-boiler applications used pulverized coal (coalground to a fine powder), which burns more completelythan larger clumps of coal.

Biomass fuel includes all types of burnable organic

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Biomass fuel includes all types of burnable organicmaterial, including rice husk, wood chips, and otheragricultural waste products.

Gas-fired boilers are designed to operate on eitherpropane or natural gas. Some gas-fired boilers can beswitched over to one or the other with some modificationsto account for the different characteristics of the fuels.

BASIC BOILER SYSTEM (cont)

Gas-fired boilers are designed to operate on eitherpropane or natural gas. Some gas-fired boilers can beswitched over to one or the other with somemodifications to account for the differentcharacteristics of the fuels.

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Oil-fired boilers used gasoline or other petroleum-based fluids as the fuel source. Thermic fluidheaters (described above) use these fluids as the heattransfer medium.

Wood is a fuel source used for some traditionalboiler designs.

BASIC BOILER SYSTEM (cont)

Electric is used in the form of either resistance heatingcoils or electrode-type units to provide heat for boilers,typically those of very low capacities or those forcommercial/domestic use.

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BASIC BOILER SYSTEM (cont)

The most fundamental decision when selecting a boiler iswhat its function will be. Boilers can either be used toproduce hot water or produce steam.

Hot water boilers are used to heat water for hot waterheating systems. Typical applications include domesticand commercial hot water needs, comfort heating, freeze

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and commercial hot water needs, comfort heating, freezeprotection, commercial dishwashers, radiant floor heating,car washes etc.

Steam boilers heat hot water to boiling in orderto generate steam for use in different applications. Theseinclude turbines for power generation, various industrialheating applications (e.g. cement production), andagricultural soil steaming.

CLASSIFICATION OF BOILERS

Boilers can be distinguished based on their designand construction, which defines their method of heatexchange. They are of three types:

Fire – tube boilers

Water – tube boilers

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Water – tube boilers

Packaged boilers

CLASSIFICATION OF BOILERS (cont)

(a) Fire tube boiler:

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CLASSIFICATION OF BOILERS (cont)

Fire-tube boilers feed hot gases from the heating sourcethrough tubes.

These tubes are positioned inside a water filled drum inorder 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 tooperate than water-tube boilers, and because of theirsimple construction also tend to have a lower initial cost.

However, because the thickness of the outer shell (whichcontains and pressurizes the water) is limited by cost andpracticality, fire-tube boilers are typically limited tolow pressure and low to medium capacity applications.

CLASSIFICATION OF BOILERS (cont)

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Fire – tube boiler

CLASSIFICATION OF BOILERS (cont)

(b) Water – tube boiler:

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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.

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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CLASSIFICATION OF BOILERS (cont)

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CLASSIFICATION OF BOILERS (cont)

(c) Packaged boilers:

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CLASSIFICATION OF BOILERS (cont)

A package boiler or packaged boiler is a modern formof steam boiler. They are factory-made to a range ofstandard designs, according to the size and evaporativecapacity required.

The advantages of a package boiler are that they are

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The advantages of a package boiler are that they areavailable 'off the shelf' without a lengthy design step andalso that they are simpler to install.

The internal arrangement of a package boiler is usually aone- or two-pass fire-tube boiler with an internal furnacetube.

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.

CLASSIFICATION OF BOILERS (cont)

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References

Dipp.nic.in

www.diydata.com/planning/central-heating/boiler.php

www.globalspec.com

Bureau of energy efficiency (BEE)

A text book on HEAT TRANSFER by S. P. Sukhatme

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A text book on HEAT TRANSFER by S. P. Sukhatme