A static air preheater A rotary air preheater
An air preheater is a heat exchanger that extracts heat from flue gas and emits it to combustion air. The intention is to increase the efficiency of a boiler or burner. An increase in return is estimated at 20% for 2% more investment.
In addition to static air heater, power plants often use a rotary air preheater as a recuperative heat exchanger due to its robust construction.
In small applications, a regular steam / air heat exchanger is sometimes used to preheat air.
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