How to Select Refractory Bricks for Coke Ovens

Refractory bricks that are easy to be hydrated should not be used in carbonization chambers and combustion chambers, because water is discharged in the low temperature state and there is a small amount of water in the combustion products during the coking process. 

The carbonization chamber and combustion chamber of coke ovens work periodically. At the end of the coking process, the actual temperature of the walls of carbonization chambers is 1000℃. When removing coke, the temperature decreases gradually. When cold coal is loaded, the temperature drops to 700℃. So, the carbonization chamber is built with silica bricks. 

 

Silica refractory brick has high strength at high temperature. Its softening temperature under load is close to its refractoriness. The refractoriness of common silica brick is 1620-1660℃, while that of high quality silica brick is more than 1660℃. It is not easy to deform at high temperature and has no crystalline transformation above 600℃ and small expansion coefficient. 

 

In regenerators, since there are large temperature changes in the sidewalls, high quality fireclay bricks are used. Sometimes, materials with different expansion coefficient may destroy the whole structure of the furnace, silica bricks are used in the sidewalls, protected with fire clay bricks in the outside. The checker bricks in the regenerators are non-load-bearing structures, so fireclay bricks are used. 

 

In the carbonization chamber, the burners at two ends and the door lining are subjected to sudden temperature changes when the door is open. The temperature drops from 1000℃ to 500℃, which is beyond the temperature range to maintain the volume stability of silica bricks(573℃). So, refractory materials with good thermal shock are used. In the past, fire clay bricks are used. Nowadays, high quality high alumina refractories (Al2O3<60%) with good thermal shock resistance are used, such as andalusite bricks and andalusite - alumina bricks. 

 

The working condition of the combustion chamber is similar to that of the carbonization chamber. So, in order to maintain the integrity of the furnace, silica bricks are widely used.