DTE Energy’s (NYSE: DTE) Detroit Edison unit is demolishing an old smokestack at the coal-fired Monroe power plant as it clears the way for new stacks that will support the latest flue gas desulfurization systems being built on the massive facility.
Demolition work resumed recently on one of the two original 800-foot exhaust stacks at Monroe, DTE noted in a May 30 statement. The original stacks date to the early 1970s and are being replaced by new 580-foot stacks built to support the operation of the new FGDs. The new stacks are necessary to accommodate the moisture that is added to the exhaust by the emissions reduction process.
The current schedule calls for demolition of the southern stack to be complete in October. The original northern stack will be taken out of service in 2014, when all four generating units will be operating with scrubbers. Pullman Power of Kansas City, Mo., is performing the stack demolition and has extensive experience in stack construction, maintenance and demolition.
As the stack demolition moves into the final phase, construction of the new emission control systems continues. Construction of the FGD systems for Units 1 and 2 is about 50% complete and on schedule for operation by mid-2014. In addition, construction of a selective catalytic reduction system (SCR) – which reduces NOx emissions by about 90% – is underway on the plant’s northernmost generating unit (Unit 2) and will be complete in 2014. SCRs are already in operation on the plant’s other three units.
The Monroe plant is the first coal-fired power plant in Michigan to operate with scrubbers. It’s also the first plant in Michigan that operates scrubbers in combination with SCR systems. When these systems are operating together, 75% to 90% of mercury emissions are eliminated. The operation of an FGD and an SCR at each generating unit will assure that the plant will meet new federal emissions standards that will take effect Jan. 1, 2015, DTE said.
Many power generators that add FGD to power plants pursue the option to burn higher-sulfur coal there, since that higher-sulfur coal is often cheaper than low-sulfur coal. But, Detroit Edison has indicated to regulators that it is going the opposite route, upping the station’s burn of low-sulfur Powder River Basin coal in blends with eastern bituminous coals. With the FGDs in place, the low sulfur content of the PRB coal is almost incidental, with Detroit Edison finding that its relative proximity to PRB coal supply makes this coal the cheapest to burn. Blends are needed since pure PRB coal can often cause operational issues, with Detroit Edison spending new money on equipment to ease those issues and allow a higher PRB percentage in the blends.
Monroe consists of four supercritical, pulverized coal-fired Babcock & Wilcox cell burner boilers with a total electric generating capacity of 3,280 MW. The four pulverized coal-fired boilers were placed into service between 1971 and 1974 and are referred to as Units 1-4.
“Detroit Edison has recently been permitted (PTI 93-09A) to add petroleum coke as a fuel and increase the utilization capacity of Powder River Basin (PRB) subbituminous coal in Units 1, 2, 3, and 4; modify the coal handling systems at the facility which includes the unloading, storage, and transfer to the boilers and rail and ship delivery of coal; and install petroleum coke handling systems,” noted a June 2011 air permitting document from the Michigan Department of Environmental Quality. “Also, enforceable restrictions were included for the operation of the new wet limestone forced oxidation flue gas desulfurization (wet FGD) systems on Units 1, 2, 3, and 4; diesel fuel-fired wet FGD quench pumps; and the associated limestone and gypsum material handling systems which includes ship unloading of limestone, storage and pile maintenance, and reclaim activities.”
That air permitting from last year, by the way, related to installation of on-site facilities for a two-year test period to produce refined coal, called reduced emissions fuel (REF). REF is regular coal with chemicals added, with the additives designed to reduce some plant emissions as that coal is burned.