THE CHARACTER OF ASH DEPOSITS AND THE THERMAL PERFORMANCE OF FURNACES

The character of fireside ash deposits depend on the processes by whic h deposits are formed and subsequent reactions within the deposit and with furnace gases. The properties influencing furnace heat transfer, absorptivity for radiative transfer and thermal conductivity for condu ctive transfer are shown from many measurements to depend on this char acter. Illustrative trends in these properties as deposits mature and grow are presented together with their effect on furnace exit temperat ure and efficiency. The reflective character of initial deposits from particular coals is then considered with predictions and measurements of the spectral character of such deposits, during the first three hou rs of growth, using on-line FTIR spectroscopy.