Refractory Application In The Ceramic Tunnel Kiln

Tunnel kiln is widely used in ceramic industry due to its high production capacity, low energy consumption and easy mechanization and automation. 

Ceramic tunnel kiln is similar to the lime calcining kiln for producing refractory bricks. The kiln includes 4 parts: kiln body, combustion equipment, ventilation equipment and transportation equipment. The kiln body is composed of kiln walls and the crown. 

 

Along the direction of the kiln, the ceramic tunnel kiln can be divided into 3 zones: preheating zone, firing zone and cooling zone. The division is mostly based on the set of combustion chambers, sometimes the masonry or temperature. 

 

The crown of the tunnel kiln is constructed with refractory bricks or prefabricated blocks cast with refractory materials. Several kiln cars are set on the bottom and move along the fixed rail. Blanks on the kiln cars are pushed into the kiln from the kiln head and out of the kiln at the kiln end after preheating, firing and cooling. 

 

The requirements of kiln walls for refractory materials are as following:

1)The kiln walls should withstand high temperature;

2)The kiln walls should have good strength to withstand the weight of the crown;

3)The kiln walls should have good insulation to reduce heat loss. 

 

The selection of refractory materials for the inner wall is up to the firing temperature. 

1)Fireclay bricks below 1300℃;

2)High alumina bricks between 1300℃ and 1400℃;

3)Silica bricks between 1400℃ and 1500℃;

4)Magnesia alumina bricks between 1500℃ and 1600℃;

5)Corundum bricks below 1800℃. 

 

To reduce heat loss, lightweight insulation materials such as light weight fireclay brick, light weight silica brick and diatomite Insulation Brick are built between the inner wall and outer wall. The type and thickness of the refractory materials used in each zone is up to its temperature.