Mitchell Station Case Study

Mitchell Station Units 1 and 2 Wet Flue Gas Desulfurization Systems

American Electric Power

Moundsville, West Virginia

The wet flue gas desulfurization (FGD) system from Babcock & Wilcox (B&W) features a combination of design components to provide a high level of reliability and removal efficiencies. These include B&W’s signature tray tower design that provides excellent gas to liquid contact and uniform flow distribution through the absorber spray zones; its patented inlet awning; interspatial headers to reduce absorber height, pump power requirements, and internal support costs; forced oxidation system; and advanced mist eliminators.

Boiler/Plant Information

• 2 x 800 MW
• Boiler type: Pulverized coal fired
• Design fuel: Bituminous
• Additional environmental equipment: Electrostatic precipitator (ESP), selective catalytic reduction (SCR) system, and a trona injection system for SO3 control.

Project Summary

• Engineering, procurement and construction of a wet flue gas desulfurization system
• System designed to remove 98% of the entering SO2 without organic acid addition
• Type: Limestone forced oxidation with gypsum byproduct
• Project awarded: March 2004
• Operation dates: January 2007 (Unit 2) and April 2007 (Unit 1)

B&W Scope

• Two (2) wet FGD absorbers (1 per boiler)
• Two (2) limestone milling systems (1 operating, 1 spare)
• Gypsum dewatering system that includes three (3) horizontal table filters (2 operating, 1 spare)
• Buildings and structural steel
• Construction of all B&W supplied equipment and structural steel, through Babcock & Wilcox Construction Co., Inc. (BWCC), a B&W subsidiary At the time of contract signing, these absorber tower modules, at 68.5 ft (20.9 m) in diameter, were the largest shop-assembled FGD modules B&W has ever designed and built.

Results

The project met every engineering, fabrication and construction schedule milestone. The commissioned units have met performance guarantees.

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