Destruction mechanism of basic refractories in flame furnace roofs

Conclusions

The main form of wear in MKhS and PShS bricks in the roof of a flame furnace is the formation of cracks at a distance of 25–50 mm from the heating surface, located in a parallel plane, and their subsequent scaling. Scaling on the boundary of the zones occurs under the action of stresses due to the temperature gradient in the thickness of the brick, and internal stresses caused by direct difference in the coefficients of thermal expansion of these zones.

The advantage of MKhS bricks is the better adaptability of the structure to stresses in the presence of fragments (elementary volumes) which have a certain capability of independent displacement under thermal loading. In connection with this, the lining of the roof of flame furnaces should be made of magnesia-spinel refractories possessing the maximum possible thermal-shock resistance with a strength that is satisfactory for the service conditions.