The use of insulation bricks in the thermal equipment can greatly reduce the heat loss and the weight of furnaces and improve the thermal efficiency and labor productivity.
For most thermal equipment, in order to save energy and improve the working conditions, insulation is necessary. However, for some equipment, insulation is not necessary, given the pros and cons of insulation. Therefore, the actual conditions and the properties of insulation bricks should be taken into consideration when selecting the right insulation bricks.
The insulation bricks can be divided into the following types:
1) Fire clay insulation brick GB/T 3994-2005
2) High alumina insulation brick
3) Mulite insulation brick
The principles for selecting insulation bricks include:
1) It should not affect the service life of the entire refractory masonry;
2) For continuously working high temperature furnaces, generally large area insulation is reasonable and can reduce the heat loss. However, for some special areas such as the open hearth roof, insulation may reduce the service life. For periodically working furnaces, regenerative heat loss is the main factor of heat loss. Insulation may increase the temperature of masonry and increase regenerative heat loss. So, whether periodically working furnaces should be insulated is determined after calculating the heat storage and heat loss.
3) Since the insulation bricks have high porosity, they cannot withstand too much load and should not directly contact the molten metals, molten slags and high-temperature dust.
4) Insulation bricks have low strength. The brick joints and expansion joints should be properly disposed avoid the damage caused by volume expansion. Insulating firebrick should not be subjected to intense mechanical vibration, shock and friction;
5) Since insulation bricks have big reheating linear shrinkage, the maximum working temperature should be 100℃ less than the firing temperature.