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Air Heaters - Continued.

Classification of Air Heaters

There are two main types of air heaters: recuperative and regenerative.

Recuperative Air Heaters

In a recuperative heat air heater, heat exchangers are used to heat the combustion air. There are many types of recuperative air heaters.

Tubular air heaters

In this type of air heating system, a heat exchanger is used which consists of tube bundles. Flue gas is made to flow through the tubes, while combustion air flows around the tubes.

Plate air heaters

In this of air heating system, plate type heat exchangers are used. In plate heaters, hot flue gas flows on one side of a plate, and the combustion air flows on the other side. A bank of alternate air and flue gas compartments is provided to facilitate easy heat transfer.

Steam coil heat exchangers

In this system, combustion air is not used to heat the combustion air. Instead, banks of finned coils are used. Steam flows through the finned tubes, and the combustion air flows around the finned coils.