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ECONOMIZER
• Purpose: Preheat the boiler feed water and recover some of the heat from the flue gases.
• Location: Rear gas pass below the rear horizontal SH.
• Staggered arrangement.
• Continuous finned tube.
ECONOMIZER
• Tube size:
OD 44.5 mm X 4.5 mm (thick).
Material – SA 210 Gr A1.
• Probable failure causes.
WJF
Erosion
DRUM• FUNCTION:To separate steam and water from the mixture
generated from water walls.Reduce the dissolved solid contents into acceptable
limits.• Size:ID – 1676 mm; Thickness – 133 mmLength – 15700 mm; hemisphere – 940 mmMaterial SA 299
DRUM
• Steam drum internals:
Feed pipe.
Separating chamber.
Turbo separators.
Screen dryers
Chemical dosing.
Blow down.
Welded Wall Construction• Water cooled furnace.
Combustion and heat transfer takes place.
Construction:
Furnace walls Membrane type.
Radiant roof is of pegfin welded construction.
Rear pass roof, and rear, front and side steam cooled wall are of fin welded construction.
WATER WALL
• Bottom construction:
Depends on fuel and ash condition.
Mostly open hopper type, often referred as dry bottom. Leakage of air between furnace and hopper is prevented by either a water impounded or a mechanical seal expansion joints.
WATER WALL• Corner/tangential fired.• Tube Dia -63.5 mm Thickness – 5.2 mm
Material – SA 210 Gr A1.• Probable failure causes.
Blistering
Erosion
Corrosion
AWF/WJF.
SUPERHEATERS
• Composed of four basic stages:Pendant section, Platen section, Rear
horizontal section, and the steam cooled wall and roof sections.
Location:Platen Section is located just above the
furnace in front of the furnace arch. Heat absorbs mainly by radiation.
SUPERHEATERS
• Pendant section is located behind the screen tubes. Predominant mode of HT is convection.
• LTSH is located in the rear vertical gas pass above economizer. This is the primary SH of the convective, counter flow type.
• SCW sections form the side, front and rear walls and roof of the vertical gas flow path.
REHEATER
• Reheater is composed of two sections namely front pendant and rear pendant vertical spaced section.
• Location:Rear pendant is located above the furnace arch
between water cooled screen and rear water wall hangers.
Front pendant is located between water wall hangers and platen section.