July 1, 2010

Regulations and Economics Drive Wet FGD Upgrades

By Angela Neville, JD

ELECTRIC POWER 2010
Today’s coal-fired power plants face the twin challenges of improving their wet flue gas desulfurization (FGD) systems’ emission control capabilities in order to comply with environmental regulations while at the same time cutting their operational and maintenance costs. Smart strategies for retrofitting existing FGD systems can help plant personnel meet both of these objectives.

“Boosting SO₂ removal rates and cutting other emissions, such as SO₃, is one of today’s top drivers for upgrading wet flue gas desulfurization (FGD) systems at U.S. power plants,” said Michael Mengel, lead process engineer, Marsulex Environmental Technologies (MET). Mengel was one of the members of the “FGD Retrofits, Upgrades, and O&M” session panel at ELECTRIC POWER 2010 who provided useful information about successful approaches to implementing wet FGD system upgrades in order to maintain environmental regulatory compliance. The session was co-chaired by Melanie Green, PE, senior manager, CPS Energy, and Peter Macios, global account executive, GE Water & Process Technology.

Reasons to Retrofit

FGD is a technology used for removing sulfur dioxide (SO₂) from the exhaust flue gases of coal-fired power plants. Typically, SO₂ is removed from flue gases by wet scrubbing, using a slurry of alkaline sorbent, usually limestone or lime, to scrub the gases.

In addition to the need to cut SO₂ emissions, today’s savvy power plant staffs are retrofitting their wet FGD systems for the following other reasons, Mengel explained:

• To switch fuels in order to use higher-sulfur coal that is less expensive.
• To eliminate the bypass process that is no longer allowed under new environmental regulations.
• To upgrade units because of their advanced age.
• To reduce maintenance and operation costs.
• To enable a facility’s by-products to be sold to other industries.

“Power plant personnel who want to increase the performance of their facility’s wet scrubber system should assess the need for possible improvements throughout the entire system,” Mengel said.

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