Major Components of Boilers
A boiler, also referred to as a steam generator, is a major component in the plant cycle. It is a closed vessel that efficiently uses heat produced from the combustion of fuel to convert water to steam. Efficiency is the most important characteristic of a boiler since it has a direct bearing on electricity production. Boilers are classified as either drum-type or once-through. Major components of boilers include an economizer, superheaters, reheaters, and spray attemperators.
Economizer.
The economizer is the section of the boiler tubes where feedwater is first introduced into the boiler and where flue gas is used to raise the temperature of the water.
Steam Drum (Drum Units Only).
The steam drum separates steam from the steam/water mixture and keeps the separated steam dry.
Superheaters.
Superheaters are bundles of boiler tubing located in the blow path of the hot gases that are created by the combustion of fuel in the boiler furnace. Heat is transferred from the combustion gases to the steam in the superheater tubes. Superheaters are classified as primary and secondary. Steam passes first through the primary superheater (located in a relatively cool section of the boiler) after leaving the steam drum. There the steam receives a fraction of its final superheat and then passes through the secondary superheater for the remainder.
Reheaters.
Reheaters are bundles of boiler tubes that are exposed to the combustion gases in the same manner as superheaters.
Spray Attemperators.
Attemperators, also known as desuperheaters, are spray nozzles in the boiler tubes between the two superheaters. These spray nozzles supply a fine mist of pure water into the blow path of the steam to prevent tube damage from overheating. Attemperators are provided for both the superheater and reheater.