Boiler is one kinds of device which generate steam at a definite temperature and pressure.
Purpose of boiler:
- For power generation as in case of steam engine or turbine.
- For processing as in case of industrial purpose like sizing, bleaching etc. In a textile industry or other industrial purposes.
- For heating as in case of heating installation for buildings.
Classification of boiler:
According to tube contents the boilers are classified into two types.
- Water tube boiler
- Fire tube boiler
Water tube boilers:
A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Water tube boilers are used for high-pressure boilers. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes. In smaller boilers, additional generating tubes are separate in the furnace, while larger utility boilers rely on the water-filled tubes that make up the walls of the furnace to generate steam. For example: Bab cock and Wilcox boiler, Benson boiler, La-Mont boiler etc.
Fire tube boilers:
In fire tube steam boilers, the flames and hot gases, produced by the combustion of fuel, pass through the tubes which are surrounded by water. The heat is conducted through the walls of the tubes from the hot gases to the surrounding water. For example: Simple vertical boiler, Cochran boiler, Cornish boiler, Locomotive boiler etc.