Wet Flue Gas Desulfurization

Wheelabrator WFGD (absorber; Wet Flue gas desulfurization) SO2 removal air pollution control

benefits and Features

  • >98% removal of sulfur dioxide (SO2)
  • Integral absorber and recycle tank
  • Self-supported internal recycle headers provide optimal slurry distribution within the absorber zone
  • Open tower and Dual Flow Tray designs
  • Absorber vessels are custom designed to meet clients’ needs
  • Experience with all absorber materials (alloys, cement, rubber and glass linings)
  • Full range of reagent and by-product experience
  • Broad experience in upgrading existing WFGDs

Our wet FGD systems have been effectively controlling emissions from coal-fired boilers and industrial processes for decades. This vast experience enables our engineers to custom design new systems and evaluate, rebuild/upgrade current systems to provide solutions to the most stringent environmental regulations.

  • WFGDs provide excellent capture of SO2, acid gases, mercury, heavy metals, and PM
  • Ideal for applications with high inlet SO2 and high SO2 removal (>95%) requirements
  • Wide application to coal, oil, biomass and solid waste in power and industrial boilers
  • Forefront in ELG (Effluent Limitation Guidelines) research. Single source technology provider to meet ELG regulations
High degree of customization to meet project and customer needs


Coal or Oil fired boilers
Hazardous and municipal solid waste
Oil refineries

Cement Kilns

Eastern High Sulfur Coal

Eastern Bituminous

Illinois Basin High Sulfur Bituminous

Powder River Basin (PRB) Coal

Blended Coal and Pet Coke

High Sulfur Fuel Oil


How it Works

Wheelabrator Wet Flue Gas Desulfurization (WFGD) with SO2 removal and air pollution control

  • Absorber slurry is continuously pumped from the recycle tank to the spray headers.
  • The flue gas and absorber slurry are contacted counter-currently (Gas flows upward, absorber slurry downward).
  • Acid Gasses (SO2 / SO3 / HCl / HF / Hg 2+) are absorbed by the scrubbing liquor and fall into the recycle tank.

  • Chemical reactions take place in recycle tank to form Calcium Sulfite / Calcium Sulfate (gypsum).
  • Fresh reagent is continuously added to the recycle tank to maintain slurry alkalinity via pH control.
  • Air is added to the recycle tank to promote favorable reaction of calcium sulfite to calcium sulfate (gypsum)
  • The treated flue gas passes through multi-stage mist eliminator modules which trap entrained drops before the flue gas exits.

Special Features

WFGD/absorber dual flow tray for increased SO2 removal and acid gas removal

Dual Flow Tray (DFT)
  • DFTs dramatically improve absorber performance well beyond open tower designs
  • Lower liquid to gas ratio
  • Smaller footprint
  • Optimized flue gas distribution
  • Easier absorber maintenance
  • Lower capital cost
  • Multiple DFTs can be provided to improve performance on both new and existing WFGDs

Absorber (WFGD) recycle spray header for SO2 removal and acid gas removal

Spray Headers
  • Optimized arrangement for maximum spray coverage
  • Single absorber entry
  • Self-supporting

Absrober stebbins recycle tank for SO2 removal and acid gas removal

Absorber Recycle Tank
  • Large recycle tank reduces scale, and produces large, easily dewatered gypsum by-product
Stebbins Lined Absorber option
  • Improved corrosion resistance
  • Allows high chloride operation and reduced FGD waste stream

Design Flexibility
  • Only Supplier offering Open Tower, Dual Flow Tray (DFT), and multiple DFT’s
  • DFT offer SO2 removal > 99%, Lower L/G ratio, smaller footprint, easy maintenance
  • Experience with variety of reagents (Limestone, Lime, Sodium)
  • Broad materials experience (Alloy (317 LMN, 2205, 6 Moly, C-276 clad), Concrete Tile Lined (Stebbins), Carbon Steel with Flakeglass Lining

Continued Support
  • Start-up
  • Inspections
  • Rebuild/Upgrade
  • R&D
  • WFGD Users Group


Recent Projects

Wet FGD Miami Smelter SO2 revoval

Miami Smelter

Location: Claypool, AZ, USA
Customer Freeport-McMoRan Miami Inc.:
Design: DFT Absorber
Reagent: Sodium Hydroxide
Start-Up Year: 2017 scheduled
Gas Treated: Copper Smelter Converter Aisle and Anode Furnace
Gas Flow: 1,519,650 ACFM
(2,581,900 m3/hr)
SO2 Removal: 98%

Longview Wet FGD upgrade with increased SO2 removal

Longview Station WFGD Modifications

Location: Maidsville, WV, USA
Customer: Longview Power
Modification: Single to Double DFT Absorber
Reagent: Limestone
Plant Capacity: 750 MWe
Start-Up Year: 2015
Fuel: Eastern Bituminous Coal
Gas Flow: 2,168,118 ACFM
(3,683,656 m3/hr)
SO2 Removal: Up to 98.6%

Public Service of New Hampshire wet flue gas desulfurization (WFGD) for SO2 control and mercury control

PSNH Merrimack Station, Units 1-2

Location: Bow, NH, USA
Customer: Public Services of NH
Design: DFT Absorber
Reagent: Limestone
Plant Capacity: 457 MWe
Start-Up Year: 2012
Fuel: Bituminous Coal
Gas Flow: 1,628,000 ACFM
(2,767,600 m3/hr)
SO2 Removal: Up to 97%
HF, HCl Removal: Up to 99%
Hg Removal: Up to 86%

Dallman station WFGD updrade for increased SO2 removal

Dallman Station, Unit 33 WFGD Modifications

Location: Springfield, IL, USA
Customer: City of Springfield
Modification: Dual loop to DFT Absorber
Reagent: Limestone
Plant Capacity: 192 MWe
Start-Up Year: 2011
Fuel: Illinois Bituminous Coal
Gas Flow: 913,000 ACFM
(1,552,100 m3/hr)
SO2 Removal: Up to 98%

PSNH Merrimack Station was the First Utility Scrubber Designed for Mercury Removal in the USA

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