Major and Minor Element Distribution in Fly Ash from a Coal-Fired Utility Boiler in Kentucky

Study of the combustion of a multiseam blend of southeastern Kentucky high volatile A bituminous medium sulfur coal in a 220-MW wall-fired utility boiler demonstrated that there is significant asymmetry in the distribution of major elements and oxides, including sulfur and carbon, and minor elements in the ash collection system. Partitioning of volatile elements, such as Zn and As, according to flue gas temperature is a well-known phenomenon. Hg distribution is related to both the flue gas temperature and the amount of carbon in the fly ash. In addition, many elements show a distinct lateral asymmetry within individual rows of the ash-collection system. Certain aspects of the element distribution appear to be related to the carbon distribution. Hg is an example of an element with a lateral distribution tied to carbon. Other elements, such as Mo, As, Mn, and Cr, may be incidental relationships, tied to the relative increase in glassy fly ash constituents in the absence of carbon.

Keywords:

• coal
• combustion
• fly ash
• arsenic
• mercury