Air Heaters - Continued.

Regenerative Air Heaters

In this type of air heaters, heat is transferred from the flue gas to the combustion air in an indirect manner. In essence, in this system, a heat transfer metallic body is alternately heated and cooled.

The heat transfer body is heated by the flue gas and then cooled by the combustion air. In this process, the combustion air picks up heat from the hot heat transfer body.

In thermal power plants, tightly packed bundles of corrugated steel plates serve as the heat transfer medium. In such units, the steel plates or the surface elements, rotate through air and gas streams. This allows the flue gas to heat the rotating element, followed by cooling of the same by the combustion air. The net result is transfer of heat energy from hot flue gas to the combustion air.