Steam Boiler
Steam is used for power generation, process heating and for many industrial processes. To produce the steam at required pressure and temperature boiler is used. Boilers are also known as steam generators.
It is a closed vessel made of high quality steel in which steam is generated from water by application of heat. Water receives the heat from hot gases through the heating surface of boiler. The steam yenerated is collected over water surface.
Classification of Boilers:
Classification of Boilers according to:
1. Relative Position of Water and Hot Gases:
(a) Fire tube boiler: In fire tube boilers, hot gases pass through tubes, which are surrounded with water. There may be single tube as in case of Locomotive boiler or there may be bank or set of tubes as in the Lancashire boiler. Examples of Fire tube boiler: Lccomotive boiler, Lancashire boiler and Cochran boiler.
(b) Water tube boiler: In water tube boilers, the water circulates through the large number of small diameter tubes and hot gases around them. Steam is generated inside tubes and collected in a cylindrical vessel known as boiler drum. Examples of water tube boiler: Babcock and Wilcox boiler, Stirting boiler, Lamont boiler, Volex boiler and Benson boiler.
2. According to Axis of Boiler Drum:
(a) Horizontal boiler: In this type of boiler, the boiler drum or shell is in horizontal position.
(b) Vertical boiler: în this type of boiler, the boiler drum or shell is in vertical position.
(c) Inclined boiler: In this type of boiler, the boiler drum is in inclined position.
3. According to Position of Furnace:
(a) Externaliy fired boiler: When furnace is located outside the boiler shell, the boiler is known as externally fired boiler. Example: Babcock and Wilcox boiler.
(b) Interna!ly fired boiler: When furnace is located within the boiler shell, the boiler is known as interral!v fired hoiler Evamnla: l ancachire boiler
4. According to the Method of Water Circulation:
(a) Natural circulation boiler: In this type of boiler, the circulation of water is by natural convection currents, which are set up due to temperature difference. Example: Lancashire boiler, Babcock and Wilcox boiler.
b) Forced circulation boiler: In this type of boiler, the circulation of water is achieved by means of motor driven centrifugal pump. Forced circulation is generally provided for high- pressure boilers. Example: LaMont boiler, Benson boiler, Volex boiler. ·
5. According to Use of Boiler:
a) Stationary boiler: Most of the boilers used for power generation and industrial use are stationary type.
(b) Mobile boiler: The boilers used to run locomotives and ships are mobile boilers as they continuously move from place to place.
6.According to Number of Tubes:
a) Single tube boiler.
(b) Multi-tube boiler.
Tech GALAxY GURU 
Leave a comment