The Tennessee Valley Authority plans to burn begin co-firing wood along with coal at its Paradise power plant in western Kentucky, said the Kentucky Department for Environmental Protection.
The DEP’s Division for Air Quality is going out on Jan. 16 for comment on a draft Title V air permit renewal for the Paradise plant. On April 30, 2012, TVA submitted the renewal application. Supplemental information was submitted on Aug. 13, 2012, in response to a notice of deficiency issued by the division. Additional information was submitted electronically on Dec. 10, 2012.
The Paradise facility consists of three cyclone-furnace coal-fired boilers, three distillate oil-fired heating boilers, eleven distillate oil-fired space heaters, three natural-draft cooling towers, and solid fuel, limestone, ash, and gypsum handling processes. The coal used to fuel the boilers is delivered by rail, truck and barge.
Currently, most of the coal is cleaned in a coal wash plant prior to delivery to the coal fired boilers, with distillate fuel oil (fuel oil) being used for the start up. The boilers also combust fuel oil under non-steady state and low load conditions to ensure flame stability. These units are also fueled using approximately 100,000 gallons of used oil and non-hazardous solvents along with various other waste materials.
“[Paradise] is currently cofiring coal fines and plans to begin cofiring wood waste in the main boilers,” said a DEP “Statement of Basis” document. “The maximum percentage of coal fines blended with other coal is about fourteen (14) percent by weight, even though a range of six (6) to eight (8) percent by weight is the expected rate. Waste products from sawmills and other wood-working facilities will be burned at a maximum of 5% of the boilers heat input (13% by weight).”
Emission units 1 and 2 are identical cyclonic steam boilers, each having a maximum capacity of 6,959 MMBtu/hr, with nameplate capacity of 704 MW. The units are equipped with overfire air to reduce NOx, and the boiler exit flue gas is routed through the selective catalytic reduction (SCR) modules for additional NOx control. The flue gas flows through venturi-type limestone slurry flue gas desulfurization (FGD) scrubbers for the removal of SO2 and other pollutants.
Emission unit 3 is a cyclonic steam boiler with a maximum capacity of 11,457 MMBtu/hr. The nameplate capacity is 1,150 MW. The unit is also equipped with staged overfire air to reduce NOx. Just like units 1 and 2, the flue gas furnace section may be directed to the SCR for NOx control. The flue gas flows through the electrostatic precipitators (ESP) for PM removal and flyash collected by the ESP is sluiced by a wet fly ash handling system to the pond for disposal. Alternatively, TVA may bypass the FGD for emission unit 3 for a limited period to address scrubber malfunction and maintenance.