A boiler is a device that generates steam by heating water with a fuel source in a furnace. There are two main types of boilers: fire-tube boilers, which have tubes that pass hot gases from the furnace around which water circulates; and water-tube boilers, where water circulates through tubes surrounded by hot gases. Water-tube boilers produce more and hotter steam and are commonly used in power plants, factories, and other industrial applications. A boiler works by using a furnace to heat water and create steam, which can then power machines like steam engines.
2. WHAT IS A BOILER? device for generating steam. It consists of two principal parts: The furnace: which provides heat, usually by burning a fuel, and the boiler proper, a device in which the heat changes water into steam. A steam engine is driven by steam generated under pressure in a boiler. The amount of steam that can be generated per hour depends upon the rate of combustion of the fuel in the furnace and upon the efficiency of heat transfer to the boiler proper. Since the rate of combustion of the fuel in a furnace is largely dependent upon the quantity of air available, i.e., upon the draft, a sufficient supply of air is an important consideration in boiler construction. In some large installations the incoming air is preheated by the waste heat of the flue gases, and in order to increase the speed of combustion a forced draft (air at higher than atmospheric pressure) is often used..
5. TWO MOST COMMON TYPES OF BOILERS fire-tube boilers, containing long steel tubes through which the hot gases from the furnace pass and around which the water to be changed to steam circulates, and water-tube boilers, in which the conditions are reversed. Water is changed to steam in these continuous circuits and also is super-heated in transit. This additional heating of the steam increases the efficiency of the power-generating cycle. The
6. water-tube boilers, which produce more and hotter steam, are used in ships and factories. The largest are found in the central-station power plants of public utilities; other large units are used in steel mills, paper mills, oil refineries, and chemical plants.
8. XThe safety valve safety valve, device attached to a boiler or other vessel for automatically relieving the pressure of steam before it becomes great enough to cause bursting. It is used to prevent explosions by releasing steam if the pressure becomes too great.