The thermal insulation layer of the kiln lining is to protect the furnace shell and save energy. Materials such as lightweight insulation refractory bricks and lightweight insulating castable ，ceramic fiber boards are often used as the thermal insulation layer.
Different materials of insulating refractory bricks are used at different temperatures. Since the pores of lightweight insulating refractory bricks or castables are larger than those of heavy materials, they are prone to shrinkage and deformation when heated during use. Therefore, insulating refractory bricks or castables of different materials must be selected under different temperature conditions to maintain the stability of the insulation layer in the furnace lining. If shrinkage occurs, it is likely to cause the insulation layer in the furnace body to deform or crack, increasing heat dissipation losses.
Therefore, when choosing lightweight insulating refractory bricks or insulation materials, it mainly depends on the ability to resist shrinkage and deformation under heating. The use temperature of insulating refractory bricks generally increases with the increase in volume density. When the volume density is too high, the insulation effect is not good. When the volume density is small, the insulation effect is good, but the strength is too low and it is extremely easy to peel off.
The following are the different suitable temperatures for thermal lightweight insulating refractory bricks or castables for reference:
The service temperature of slag wool is 600℃.
The use temperature range of perlite insulation material is 50-1000℃;
The use temperature range of calcium silicate insulation board is 650-1000℃;
The use temperature of vermiculite insulation material is 1000-1150℃;
The applicable temperature of diatomaceous earth insulating refractory bricks is 1000-1200℃;
Refractory ceramic fiber 1000-1300℃;
Anorthite lightweight insulation bricks are suitable for temperatures of 1100-1300°C;
The applicable temperature of lightweight clay insulation bricks is 1000-1350℃;
The applicable temperature of lightweight high-aluminum insulation bricks is 1350-1500℃;
The applicable temperature of lightweight silica insulation bricks is 1500-1550℃;
The service temperature of polycrystalline alumina fiber is 1400-1600℃;
The use temperature of mullite lightweight insulating refractory bricks is 1350-1650℃;
The use temperature of lightweight corundum insulation bricks is 1650-1800℃;
Alumina hollow ball insulation bricks 1650-1800℃;
The applicable temperature of zirconia fiber and hollow ball insulation bricks is 1800-2000℃.
That is to say, under different temperatures, it is necessary to choose insulating bricks or castables suitable for the operating temperature, or fiber materials as the insulation layer.
