Published: September 18, 2007 08:22 am         

Busting fly ash buildup

Grand River Dam Authority’s coal fired plant has a problem. One that must be removed with dynamite.

Assistant General Manager of Thermal Generation, Charles Barney, told GRDA’s Board of Directors the build up of ash in the coal fired plant’s equipment is costly when the buildup requires the unit be shut down to remove the deposits. The fly ash becomes so hard, dynamite charges must to used to remove them.

Barney asked the directors to approve a chemical treatment to reduce the buildup, called fouling. Although a year’s trial with the chemical treatment will cost $2.1 million, Barney expects the improved efficiency of the unit will save GRDA $8 to $9 million in power which must be purchased when the unit goes down due to fouling.

One pound of magnesium hydroxide, at a cost of 50 cents, will treat one ton of coal.

“The technology is well established,” Barney said. “It costs our customers money if ash clog shuts the unit down and power must be purchased.”

Fuel Tech, Inc. explained their product works by injection into the deposits. The magnesium hydroxide molecule has water in the center. Under the extreme temperatures in the boiler, it explodes, turning the deposits back into powder.

Fuel Tech’s representative said the fees get cheaper once the system is all clean. He said the company has never had a case where they were not asked to continue the program after a year’s demonstration.

Unit 2 will be down for a maintenance outage in October. It will be cleaned during that outage, to begin the chemical treatment in good condition.

Fuel Tech supervises every chemical delivery and services their equipment.

The layer of ash has built up to 18 inches thick at times. “Most other coal fired plants have a worse problem,” Barney said. “We are all looking for a solution.”

There is no chemical danger to people from this process. “This is commercial grade milk of magnesia,” Barney said.

The directors approved the one year demonstration program at a cost of $2,160,000.

     

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