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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
AIR PREHEATER
• Air Pre-heater is an auxiliary equipment for
steam boilers. It is a heat exchanger that
absorbs heat from exit flue gas in boilers
and transfers the heat to the cold air. In
utility and process boilers it is used to heat
the air required for combustion
and to dry and transport coal. purpose
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
TYPES OF AIR PRE HEATERS
RECUPERATIVE
-Tubular Heater
-Plate Type Heater
-Steam Coiled Heater
REGENERATIVE
-Ljungstrom Air Pre Heater
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
RECUPERATIVE AIR PREHEATER-
In Recuperative type Air Preheater two fluids flow at
different temperatures in a space separated by a solid
partition.
ConductionHeat is the
through transferred
separatingbywall.
Convection &
Tubular Air Preheater, Plate Type Air Preheater &
Steam Coil Air Preheater (SCAPH).
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TUBULAR –APH
Advantages:
Nothaving any moving parts.
Small Nominal leakages of air to gas.
No auxiliary power consumption.
Problems
Large for thermal duty.
Difficult to clean.
Do not allow replacement of damaged heating surface.
The ductings for cold and hot air require additional
space and structural supports compared with the
Ljungstrom design
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
Ljungstrom Air Pre Heater
In Regenerative type Air Preheater, one heating surface
is exposed
fluid at certain
and then to a intervals
cold one.ofThe
timesurface
first toofa hot
the
Regenerative Air Preheater first removes heat from the
hot fluid and is itself heated in the process, then the
surface gives up this heat to the cold fluid
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
Application - Air Pre Heater
To heat fresh air using
heat of flue gas for :
Primary Air :
To remove moisture
pulverized coal from
Secondary Air :
To assist combustion in
boiler
Air Pre Heater,
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Vertical Inverted, Trisector 7/15
5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
Rotor
COMPONENTS OF RAPH
Rotor Post
Modules
Heating elements
Bearings
Housing
Connecting Plates
Sealing Arrangements
Drive units
Cleaning devices
Safety Devices
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
HEATING ELEMENTS
End Height Of
Heating Material Description of
Elements
Elements
Hot 300mm Carbon Steel Double
Corrugated
Inter-1 800mm Carbon Steel Double
Corrugated
Inter-2 800mm Carbon Steel Double
Corrugated
Cold 300mm Corrosion resistance steel Notched Plate
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
THRUST BEARING-
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AIR PRE HEATER
SEALING ARRANGEMENT
Radial Seals
Axial Seals
Bypass Seals
Rotor Post Seals
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Sealing system
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
Ljungstrom Regenerative Air Preheater (RAPH)
Advantages:
Significant reduction in overall size and weight.
Easy and economic replacement of heating surface
with separate cold end and hot end packs.
Problems
High Air leakages resulting high fan power.
Dust carry over to furnace is high causing ash erosion
of boiler tubes in burner panels
Baskets are subjected to abrasive wear , hence
frequent replacement of the baskets are required.
Prone to air heater fire , the problem is aggravated
during oil firing
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5/21/2018 Air Pre He a te r In the r ma l powe r pla nt - slide pdf.c om
THANKS
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