A recent trend in the use of refractory materials for tube wall protection in waste-to-energy
boilers has included a combination of castable silicon carbide cement and refractory tiles. The
system is installed by first dry-setting the silicon carbide refractory tiles, then casting a selfflowing
silicon carbide cement behind the tiles. This system provides a double layer of refractory
protection, as well as increased heat flow through the refractory that leads to lower temperatures
in the upper boiler sections and less slagging on the refractory in the hot zones.
These installations are widely used in Europe and are now gaining experience in the United
States. Design considerations included heat transfer calculations, thermal expansion
considerations and tile attachment and fit schemes. Results to date have been very favorable in
terms of refractory life and boiler performance.