Tunnel roasting kiln can be divided into straight tunnel kiln (with kiln car) and mobile rotary tunnel kiln (without kiln car). Straight tunnel kilns can be further divided into masonry tunnel kilns and prefabricated tunnel kilns in terms of construction methods. The mobile rotary tunnel kiln belongs to the assembled tunnel kiln.

Straight Tunnel Kiln:

(1)   Main products: sintered bricks, common bricks, porous bricks, hollow bricks/blocks, roof tiles, hollow wall panels.

(2)   According to the different output, the inner width of the tunnel kiln is divided into the following types:

① the inner width is 3.6 and 3.7 meters, suitable for daily output of 150,000-200,000 blocks, and annual output of 50-66 million (common bricks)

② the inner width is 4.6 and 4.8 meters, suitable for daily output of 210,000-250,000 blocks, and annual output of 69-82 million (common bricks)

③ the inner width is 5.4 and 5.6 meters, suitable for daily production of 260,000-300,000 pieces, and annual output of 85-100 million (common bricks)

④ the inner width is 6.9 and 7.2 meters, suitable for daily output of 310,000-400,000 blocks, and annual output of 102-132 million (common bricks)

⑤ the inner width is 9.2 and 9.4 meters, suitable for daily output of 600,000-620,000 pieces, and annual output of 165-200 million (common bricks)

(3)   Kiln Body Structure

Masonry Tunnel Kiln:

The kiln wall is a composite wall, and the innermost layer is the working layer in contact with the high temperature. It is usually built with refractory materials (common bricks can be sintered below 600°C). The materials, grades and specifications of the refractory materials used are determined according to the firing temperature of the kiln. The middle layer is the thermal insulation layer, which is composed of various lightweight thermal insulation materials. The selected lightweight thermal insulation materials should not only provide thermal insulation, but also maintain long-term safe use without damage. The outermost layer is a load-bearing protective layer, which is multi-purpose sintering. This layer is mostly built with sintered common bricks and porous bricks to protect the lightweight thermal insulation material from damage and to bear the load of the kiln roof and the transverse thrust of the vault.

The roof of the kiln is a composite kiln item, which is hoisted on site. Commonly used kiln roof structures are refractory fiber module + refractory fiber blanket + sealed castable + steel beam; clay refractory slab + high alumina hanger + refractory fiber blanket + sealed castable + steel beam; light mullite Brick + high-aluminum hanging column + refractory fiber blanket + sealing castable + steel beam.

      (4) Firing temperature: 950-1050℃

      (5) Firing cycle: 26-40h

      (6) Length of tunnel kiln: 110-170m

      (7) Length and size of kiln car: It is determined according to the size of the billet stack and the internal and external combustion method. The length and size of the commonly used kiln car are: 3600mm, 3900mm, 4100mm, 4200mm, 4350mm, 4800mm, etc.

      (8) Firing method: all internal combustion roasting; all external combustion roasting; combined internal and external combustion roasting.

     (9) The roasting kiln is often equipped with a smoke exhaust system, a combustion system, a waste heat system, a backburning system, a cooling system, and a bottom pressure balance system. Each system consists of fans, pipes and regulating valves. The kiln has a large section, high output, small temperature difference between sections, and good thermal insulation performance. Computer automatic monitoring and control system to ensure the stability of thermal parameters and roasting quality