The cause of damage toceramic fiber insulation board of hot air furnace lining

When the hot blast stove is in operation, the ceramic fiber insulation board is subject to dramatic temperature change. The blast furnace gas is brought into the chemical attack of dust, mechanical load, and the scouring action of combustion gas. The main causes of damage to the blast furnace lining are:

(1)Thermal stress

When the hot blast stove is heated, the temperature of the combustion chamber is very high, and the temperature at the top of the furnace can reach 1500 to 1560 ° C. The temperature gradually decreases from the top of the furnace along the furnace wall and the lattice brick; when the air is supplied, the high-speed cold air blown in from the bottom of the regenerator and gradually heated up. Due to the constant heating of the hot blast stove, the hot blast furnace lining and the checker brick are often in the rapid change of temperature, so the masonry cracks and peels.

（2）Chemical erosion

The gas and combustion air contain a certain amount of alkaline oxide. The burned ash contains 20% iron oxide, 20% zinc oxide and 10% alkaline oxide. Most of these substances are discharged outside the furnace. However, a small amount of ingredients adhere to the surface of the lining. Over time, the lining of ceramic fiber insulation boards and other tissues is damaged, falling off and the strength is reduced.

(3)Mechanical load.

The hot blast stove is a tall structure with a height generally between 35 and 50 m. The maximum static load of the lower part of the regenerator compartment brick is 0.8MPa, and the static load of the lower part of the combustion chamber is also high. Under the action of mechanical load and high temperature, the shrinkage deformation and cracking of the blast furnace body affect the service life of the hot blast stove.

(4)Pressure effect.

The hot blast stove periodically performs combustion and air supply, and is in a low pressure state during the combustion period, and is in a high pressure state during the air supply period. The traditional large wall and vault structure has a large space between the vault and the furnace shell, and the filler layer of the large wall and the furnace shell leaves a certain space after natural shrinking and compaction under high temperature. Due to the existence of these spaces, the furnace body is subjected to a large outward thrust due to the pressure of the high pressure gas, which tends to cause the masonry to tilt, crack and loosen. The inclination and looseness of the masonry will naturally cause deformation and damage of the ceramic fiber insulation board, thereby completely damaging the furnace lining.