Air Preheater as name suggest is a device designed to pre heat air before entering in combustion chamber of boiler. Primary objective of Air Preheater is to increase thermal efficiency of boiler.
The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas.
There are two types of air preheaters
· tubular type (built into the boiler flue gas ducting)
· regenerative Air Preheater
These may be arranged so the gas flows horizontally or vertically across the axis of rotation.