In the operation of coke oven, it is a common problem that the silicon brick is broken due to temperature change, especially in the parts with large temperature fluctuation. The following are some measures to prevent the silicon brick from cracking:

I. Reasonable design of expansion joints

When building coke ovens, expansion joints should be reserved reasonably according to the thermal expansion rate of silicon bricks. Expansion joint can effectively absorb the volume expansion of silicon brick when the temperature changes, and avoid the brick body from cracking due to expansion stress. For example, the setting of expansion joint is particularly important in high temperature areas such as combustion chamber and carbonization chamber of coke oven.

II. Control the heating rate of the oven

During the baking process, the maximum expansion of silicon brick occurs between 100℃ and 300℃, and the expansion before 300℃ is about 70%~75% of the total expansion. Therefore, the heating rate should be strictly controlled when baking, especially in the stage before 600℃, so as to avoid cracks caused by the rapid expansion of bricks due to rapid heating.

III. Choosing the Right Type of Silicon Brick

Different types of silicon bricks have different thermal shock resistance. For example, the thermal shock resistance of dense silicon brick is better than that of ordinary silicon brick. Materials with better thermal shock resistance, such as high alumina bricks or andalusite bricks, should be selected in parts with severe temperature changes, such as furnace heads.

IV. Optimize the operation process

Reduce temperature fluctuation: In the daily operation of coke oven, drastic temperature fluctuation should be reduced as much as possible. For example, when charging coal and discharging coke, the temperature of the wall of the carbonization chamber will drop sharply, and measures should be taken to reduce the temperature change.

Avoid low-temperature operation: when the working temperature is lower than 600~700℃, the silicon brick has poor resistance to rapid cooling and rapid heating and is easy to crack. Therefore, long-term operation of coke oven at low temperature should be avoided as far as possible.

V. Improving the thermal shock resistance of silicon bricks

Adding thermal shock resistant materials: Adding materials such as andalusite and sillimanite to the silica brick can improve its thermal shock resistance.

Controlling the particle gradation of raw materials: reasonably controlling the particle gradation of raw materials and selecting raw materials with low expansion and high thermal conductivity are helpful to improve the thermal shock resistance of silicon bricks.

VI. Regular inspection and maintenance

In the process of coke oven operation, the use of silicon bricks should be checked regularly, and problems such as cracks and peeling should be found and dealt with in time. For the cracked brick body, it should be repaired or replaced in time to prevent the crack from expanding further.

Through the above measures, the risk of cracking of silicon brick due to temperature change can be effectively reduced, the service life of coke oven can be prolonged and the production efficiency can be improved.