REQUIREMENT of Air Preheater REQUIREMENT of Air Preheater | Page 2

AIR HEATER TYPES
There are two main types of air heaters are in use: the static recuperative type and
the rotary regenerative type.
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In the recuperative type, the flue gas on one side of the surface and the air on the
other side is usually transferred to the air by the heat transfer surface in the Form of tubes/
plates.
In the regenerative type, the gas flows through a tightly packed matrix or a heat
transfer element, which releases heat to the air heater elements and thus increases the
temperature of the matrix. Air will then pas through and win the heat. Either The matrix or
the hoaxes can be rotated to achieve this heat transfer as a continuous process.
Recuperative Type Air Heater
Pipe air heaters and plate heaters belong to this category. The plate heaters are
usually not used in the greater room boilers.
PLATE TIM AIR HEATER
These consist of parallel plates, which alternately provide gas air. The narrow
passes between plates make the cleaning tedious, and the exchange of plates is a big task.
As such, this type of air heater is not much use in utilities.
ADVANTAGS OF THE RECUPERATIVE AIR HEATER
The main advantage is that this type of air heater has no moving parts. Thus, the
maintenance involved less and so no additional power consumption.
Also, there is no possibility of fly ash transmitted through the heated air in these air
heaters.
DISADVANTAGES OF THE RECUPERATIVE AIR HEATER
a) since the heat transfer areas consist of tubes or plates, the air heater occupies
more area. It's also about more material costs.
b) each puncture in pipes leads to an outlet of air into flue gas flow, thereby
increasing the load on the fans.
C) deposits on the pipe surface reduce heat transfer.
d) flue gas pressure drop over the air heater is high.
e) the cross-flow heat transfer in duct air heating is less efficient.
f) is Strongly affected by cold-end corrosion.