Petrography and Chemistry of High-Carbon Fly Ash from the Shawnee Power Station, Kentucky

The Shawnee power station in western Kentucky consists of ten 150-MW units, eight of which bum low-sulfur (<1 wt %) eastern Kentucky and central West Virginia coal. The other units bum medium- and high-sulfur (> 1 wt %) coal in an atmospheric fluidized-bed combustion unit and in a research unit. The eight low-sulfur coal units were sampled in a 1992 survey of Kentucky utilities. Little between-unit variation is seen in the ash-basis major oxide and minor element chemistry. The carbon content of the fly ashes varies from 5 to 25 wt %. Similarly, the isotropic and anisotropic coke in the fly ash varies from 6% to 42% (volume basis). Much of the anisotropic coke is a thin-walled macroporous variety, but there is a portion that is a thick-walled variety similar to a petroleum coke.