Wet FGD Performance Upgrade Case Study at B.L. England Unit 2
4-Wet FGD Materials of Construction
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Transcript of 4-Wet FGD Materials of Construction
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Wet FGD
Materials of Construction
Gregory T. Bielawski
Manager,
Environmental Aftermarket Services
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .2 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .2
Inlet fluework and
dampers Inlet wet/dry interface
Recirculation tank
Spray zone & sprayheaders
Mist eliminator and
outlet flues
Wet FGD Absorber Zones
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .3 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .3
Inlet Fluework and Dampers
Absorber inlet gas temperature (typically 300F)
is well above the acid dew point Exotic materials not required
Materials can be:
Unlined ASTM A36 carbon steel or A242 corten
steel for flue, and damper frame and blade. Damper seals can be 300 series stainless
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B&WSpray Tower
Absorber
with Tray
Inlet Zone
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .4
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .5 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .5
Inlet Wet/Dry InterfaceThis interface is exposed to both the incoming dry
hot flue gas, and the absorber slurry sprays.
Due to evaporation, concentration of chloride ions
in excess of100,000 ppm is possible beneath any
deposits in this area due to concentration cells.Material choices for this area include:
High temperature flake-filled vinyl ester or epoxy
linings, or
High chrome-nickel-molybdenum alloys (solid,
clad or wallpapered)
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .6
B&W Absorber Gas Inlet with Tray
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B&WSpray Tower
Absorber
with Tray
Recirculation
Tank
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .8 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .8
Recirculation Tank
Integral to the WFGD tower structure
Tank is exposed to the same corrosion-inducingenvironment as the spray zone
In addition to corrosion concerns, abrasive wear must
also be considered for:
The floor, from solids sweeping action due to
agitator-induced and recirculation pump suction-
induced currents
Pump suction nozzles themselves
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B&WSpray Tower
Absorber
with Tray
Spray Zone
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
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Absorber Spray ZoneMultiple levels of headers with spray nozzles are used to
provide complete cross-sectional coverage
Overlapping coverage is necessary to avoid any untreatedflue gas circumventing slurry spray contact.
Slurry spray impingement (i.e. abrasion) against the shell,
other headers/supports can occur.
Material selections for impingement areas include:
Solid stainless steel or alloy
Rubber lining
Abrasion-resistant flake-filled resin coating
Ceramic tile lining
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .10
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .11
Spray Headers & Nozzles: Full Coverage
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In a Wet FGD Absorber:A Very Heavy Rainstorm !
100 L/G (gal/1000 ft3 of flue gas) in a Wet FGD absorber
operating at a typical 12 foot per second superficial gas
velocity is equivalent to 6929 inches per hour !
Imagine the heaviest rainstorm you have experienced,
which might be 6 inches of rain per hour.
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13 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
Alloy Spray Headers
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .14 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .14
FRP Spray Headers
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Taiwan Power Unit 5 One-year Inspection
FRP Spray Headers & Tray
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Trays Stay Clean
With Forced Oxidation,
all types of FGD systemstoday operate scale-free
B&W Absorber Tray
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
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Absorber Tower
Mist Eliminators
B&W Absorber
Tower
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
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2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .18 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .18
Mist Eliminator and Outlet Hood Zones
Key concern is corrosive attack by sulfurous and sulfuric acid,
resulting from the combination of wash water with theresidual SO2 and SO3 in the clean gas.
Typically the same materials used for the absorbers
recirculation tank and spray zone are used for the misteliminator and outlet zones, even though the environmentsare vastly different.
Few problems have been reported with this in kind materialsuse approach due to the dilution effect from the highmoisture, especially with condensation at the cooler shellsurface.
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Top of Level of Mist Eliminators w/ Wash Header
2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .19
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