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Boilers (A basic approach)

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This presentation may come in handy if one is interested to know about boiler and its basic aspects.

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Boilers (A basic approach)

  1. 1. Contents: 1. Introduction 2. Boiler specifications and design A basic approach 4/5/2015 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. 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 4/5/2015 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.
  3. 3. INTRODUCTION (contd.) 4/5/2015
  4. 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. 4/5/2015
  5. 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 4/5/2015 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. 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 4/5/2015  Mechanical constraints  Cost restrictions  Monetary cost  Tensile strength of material must be considered while using any joining processes
  7. 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 4/5/2015 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. 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 4/5/2015 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. 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 4/5/2015 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.
  10. 10. BASIC BOILER SYSTEM 4/5/2015
  11. 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 4/5/2015  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. 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. 4/5/2015  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. 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. 4/5/2015
  14. 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 4/5/2015 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. 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 – tube boilers Water – tube boilers 4/5/2015  Water – tube boilers  Packaged boilers
  16. 16. CLASSIFICATION OF BOILERS (cont)  (a) Fire tube boiler: 4/5/2015
  17. 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 4/5/2015  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.
  18. 18. CLASSIFICATION OF BOILERS (cont) 4/5/2015 Fire – tube boiler
  19. 19. CLASSIFICATION OF BOILERS (cont)  (b) Water – tube boiler: 4/5/2015
  20. 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 4/5/2015 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. 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. 4/5/2015
  22. 22. CLASSIFICATION OF BOILERS (cont) 4/5/2015
  23. 23. CLASSIFICATION OF BOILERS (cont)  (c) Packaged boilers: 4/5/2015
  24. 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 4/5/2015  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. 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 4/5/2015 mixing with combustion air, thus good burner performance.
  26. 26. CLASSIFICATION OF BOILERS (cont) 4/5/2015
  27. 27. 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 4/5/2015  A text book on HEAT TRANSFER by S. P. Sukhatme

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