Some Words on Drying and Preheating of Furnaces

Drying and preheating of furnaces are very important operations. If the furnace is lined with bricks, it is recommended to make the preheating after at least 24 h, so that the lining mortar and the plastic masses will become dry and become more or less rigid. In order to diminish the tensions, it is recommended to do a 24-h exposure at 800 °C after that, the heating rate is determined by the thermal shock resistance of the refractory. 

If the width of the holding furnace is 6 m, and the bottom is made from an LCC with thermal expansion 6 x 10 K the flat roof is made from MCC blocks with the same thermal expansion coefficient. If the temperature in the bottom and on the roof is 800 C, the expansion of the bottom and the roof will be 

3 Refractories and Heat Insulation Materials for the Cast House 

The calculation is made without accounting for the expansion of concrete blocks upon preheating. Only thermal expansion at increasing temperature of the fired material is calculated. 

Sometimes the gaps for the compensation of the thermal expansion are made near the walls under the side lining, and the gaps are filled with ceramic fiber materials, taking into account 50 % shrinkage of this fiber material. 

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