Flue Gas & Absorber System
Desulfurized
flue gas to
Bypass stack
Water
Mist eliminators washed
Limestone slurry with fresh water
scrubbing
absorbs SO2 to
form CaSO3 Slurry recirculated
to sprays
Flue gas from
Crushed precipitator Slurry withdrawn to
limestone remove gypsum
Gypsum solids
to Filtration
M Hydrocyclone
Air VACUUM or BELT FILTER
Water
ABSORBER
Aeration oxidizes CaSO3 to
form crystallized
CaSO 4 • 2 H2O (gypsum)
BALL MILL
Limestone is wet-ground
to produce limestone
slurry Filtrate
Thursday, April 22, 2021
Induced Draft Fans / Booster Fans
• When including AQCS equipment downstream, ID fans or Booster fans are
typically required
• Combined ID fan is an option
• Compatible with existing ID fans, if retrofit
• Typically 2X50% configuration per unit
• Design flow : 105% of BMCR condition
• Rated Head : ΔP (Duct + Absorber + Wet chimney) + SCR
• Material of Construction:
– Casing : High BHN Cast steel
– Blade : Nodular Cast Iron or High Wear Resistant Steel
Thursday, April 22, 2021
Absorber & Internals
• Spray or Spray/Tray
Tower
– Reaction tank
– Wet dry interface
– Absorber tower
– Spray levels / Tray
– Mist eliminator & wash
water piping
– Agitators
– Oxidation air spargers
Thursday, April 22, 2021
Absorber & Internals – Conceptual design
• Absorber Tower
D
D : Diameter of spray zone
V : Satd. Flue Gas Volumetric Rate (m3/hr)
v: Superficial Gas Velocity 4.2 m/s (14 fps)
Example:
15 m
Thursday, April 22, 2021
Absorber & Internals – Conceptual design
• Wet FGD Reaction Tank
- Minimum Liquid Residence Time: 4.5 min
- Uses the recycle stream
- Minimum Solids Residence Time: 16 hours
- Uses the bleed stream
: Tank Volume based on min. liquid residence time
: Volume of recycle stream (m3/hr)
: Minimum liquid residence time
: Tank Volume based on min. solid residence time
: Volume of bleed stream (m3/hr)
: Minimum solid residence time
Thursday, April 22, 2021
Absorber & Internals – Conceptual design
• Wet FGD Reaction Tank
• > Diameter based on
• < Diameter based on
• Reaction tank diameter must be equal to or
larger than the spray zone diameter
Thursday, April 22, 2021
Absorber & Internals – Conceptual design
• Absorber Module
- Spray zone area depends on
flue gas volume and the
superficial gas velocity
- Total tank volume depends on
minimum liquid or minimum
solid residence times,
whichever results in larger
reaction tank
Thursday, April 22, 2021
Absorber & Internals
• Material of Construction
– Reaction tank & Absorber tower : Carbon steel with
Flakeglass / rubber-lined, C-276 clad, SS 317LMN,
Ceramic tile lined carbon steel, Ceramic tile lined or
PP tile lined concrete, AL6XN
– Wet dry interface : C-276 (solid, wallpaper, clad)
– Spray levels : FRP with SiC coating
– Spray nozzles : SiC
– Mist eliminator : Polypropylene
– Agitators : Alloy 926
– Oxidation air spargers : C-276
Thursday, April 22, 2021
Absorber & Internals
• Material of Construction
Class Material Chloride Concentration
Stainless – 316L <1,000 ppm
Stainless Steels
4% Mo Stainless – 317LMN <8,000 ppm
Duplex Stainless – Alloy 2205 <12,000 ppm
Super Duplex Stainless – Alloy 255 <20,000 ppm
6% Mo Stainless – 6XN <30,000 ppm
Nickel Based Alloy – C-22 or C-276 <50,000 ppm
FRP >50,000 ppm
Tile Lined Concrete <70,000 ppm
Liners
Flake Glass Lined Carbon Steel <100,000 ppm
Rubber Lined Carbon Steel <100,000 ppm
Thursday, April 22, 2021
Absorber & Internals
Thursday, April 22, 2021
Chimney
• Chimney Flue
- Based on Flue Gas Volume and Velocity
- Velocity for “Dry” Operation: 20-30 m/s
- Velocity for “Wet” Operation: ≤ 17 m/s
D
D : Diameter of spray zone
V : Flue Gas Volumetric Rate (m3/hr)
v: Gas Velocity (m/s)
http://energythic.com/view.php?
node=185
Thursday, April 22, 2021
Absorber & Internals
• Material of Construction
– Wet Chimney :
• Mild steel with borosilicate
lining
• Acid resistant bricks
• C-276 clad CS
• Titanium clad CS
• FRP
– External surface of chimney
flue liner projecting over the
chimney roof : Wrapped with
2 mm thick Titanium / C-276
– Condensate collection
Thursday, April 22, 2021
Slurry Circulation Pumps
• Horizontal centrifugal type
• End suction top discharge nozzles
• Operates at ~ 18% slurry concentration
• N+1 Spray level with pump
• One dedicated pump for each spray level
• Flow is based on L/G ratio
• Material of Construction:
– Casing : Hi chrome alloy, CS or CI with rubber lined / SiC lined, CD4MCuN
– Impeller : Hi Chrome alloy with SiC coating, Cr30A
– Shaft : Duplex stainless steel
Thursday, April 22, 2021
Oxidation Air Blowers
• Sized to supply air with stoichiometric air requirements of
at least 2.0 times
• Single stage Centrifugal type
• N+1 redundancy
• Material of Construction:
- Casing : Cast iron
- Impeller : Aluminum alloy, Stainless steel
- Shaft : Forged carbon steel
Thursday, April 22, 2021
Oxidation Air Blowers
Forced oxidation air is delivered through these nozzles.
They are located just above access hole for agitators.
Thursday, April 22, 2021
Flue Gas Duct
• Designed for maximum positive and negative pressure :
-150 / +660 mmwc
• Velocity : Less than 15 m/s
• Duct shall be sloped; Drains connected to absorber
• Material of Construction:
- Inlet duct: Carbon steel
- Outlet duct : Carbon steel with rubber lining
Thursday, April 22, 2021
Vacuum Belt Filters
Cake wash
Slurry feed
Product
discharge
https://www.youtube.com/watch?v=6voXE1HxYsY
Thursday, April 22, 2021
Vacuum Belt Filters
• 2X100% configuration
• Variable speed drive
• Components
– Belt filter
– Vacuum pump
– Air water separator
– Cloth washing tank & pumps
– Cake washing tank & pumps
• Inlet concentration : 45% to 50%
• Outlet concentration : 90%
Thursday, April 22, 2021
Vacuum Belt Filters
• Vacuum applied : 0.3 to 0.8 bar
• Belt speed : 0.5 to 10 m/min
• Material of construction :
– Frame : CS with corrosion resistant painting
– Filter cloth : Polyester / Polypropylene
– Belt : Soft rubber
– Wetted steel parts: CS with plastic lining
– Discharge chute : CS with plastic or PP lining
– Vacuum receiver tank : CSRL
Thursday, April 22, 2021
Vacuum Belt Filters
https://www.youtube.com/watch?v=IxP5EXRct80
Thursday, April 22, 2021
THANK YOU
Thursday, April 22, 2021
Ducts, Damper & Seal air fans
Thursday, April 22, 2021
Damper & Seal air fans
• Types
– Guillotine : Booster fan inlet / outlet
– Multi-louver : Bypass duct / Booster fan inlet
• Booster fan inlet & outlet dampers : Motor operated
• Bypass duct dampers : Pneumatic operated
• 99.95% leak tightness without seal air fans
• 100% leak tightness with seal air fans
• Duct shall be sloped; drains connected to absorber
• Material of Construction (for wet FGD retrofit):
- Booster fan inlet, outlet, bypass : Carbon steel
- Absorber outlet : By vendor (C276)
Thursday, April 22, 2021
Reagent Handling and Preparation
Desulfurized
flue gas to
Bypass stack
Water
Mist eliminators washed
Limestone slurry with fresh water
scrubbing
absorbs SO 2 to
form CaSO3 Slurry recirculated
to sprays
Flue gas from
Crushed precipitator Slurry withdrawn to
limestone remove gypsum
Gypsum solids
to Filtration
M Hydrocyclone
Air VACUUM or BELT FILTER
Water
ABSORBER
Aeration oxidizes CaSO3 to
form crystallized
CaSO 4 • 2 H2O (gypsum)
BALL MILL
Limestone is wet-ground
to produce limestone
slurry Filtrate
Thursday, April 22, 2021
Wet Ball Mill
• Conventional ball mill slacker
• Rotating cylinder
• Steel balls create the grinding action
• Ball mills grind the grit
https://www.youtube.com/watch?v=tL21JCLG9s8
Thursday, April 22, 2021
Wet Ball Mill
• 2X100% configuration
• Main drive connected to peripheral gear
• Auxiliary drive for inching of mills during start-
up / maintenance
• Sound level < 90 dB A
• Material of construction:
– Mill body & wet parts: CSRL
– Balls : Forged carbon steel
Thursday, April 22, 2021
Reagent Handling and Preparation
Desulfurized
flue gas to
Bypass stack
Water
Mist eliminators washed
Limestone slurry with fresh water
scrubbing
absorbs SO 2 to
form CaSO3 Slurry recirculated
to sprays
Flue gas from
Crushed precipitator Slurry withdrawn to
limestone remove gypsum
Gypsum solids
to Filtration
M Hydrocyclone
Air VACUUM or BELT FILTER
Water
ABSORBER
Aeration oxidizes CaSO3 to
form crystallized
CaSO 4 • 2 H2O (gypsum)
BALL MILL
Limestone is wet-ground
to produce limestone
slurry Filtrate
Thursday, April 22, 2021
Classifiers / Hydrocyclones
https://www.youtube.com/watch?v=hirwNVDlevg&feature=youtu.be
Thursday, April 22, 2021
Classifiers / Hydrocyclones
Thursday, April 22, 2021
Classifiers / Hydrocyclones
• Static equipment, works based on medium
density difference
• 2X100% configuration
• Material of construction : Body & wet parts:
CSRL
Gypsum Gypsum
Wet Ball mill dewatering dewatering
Description
Classifier Primary Secondary
Hydrocyclone Hydrocyclone
Feed slurry 50% 15% 5%
Underflow 60% 50% 15%
Overflow 30% 1% 2%
Thursday, April 22, 2021
Gypsum Dewatering System
Desulfurized
flue gas to
Bypass stack
Water
Mist eliminators washed
Limestone slurry with fresh water
scrubbing
absorbs SO 2 to
form CaSO3 Slurry recirculated
to sprays
Flue gas from
Crushed precipitator Slurry withdrawn to
limestone remove gypsum
Gypsum solids
to Filtration
M Hydrocyclone
Air VACUUM or BELT FILTER
Water
ABSORBER
Aeration oxidizes CaSO3 to
form crystallized
CaSO 4 • 2 H2O (gypsum)
BALL MILL
Limestone is wet-ground
to produce limestone
slurry Filtrate
Thursday, April 22, 2021
