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Introduction to tunnel kiln
Tunnel kilns are key thermal equipment for ceramics, refractory materials, electric porcelain and other enterprises, and they are also energy-consuming equipment. A tunnel kiln is generally a long linear passage with fixed kiln walls and a kiln roof. A track is laid at the bottom to run the kiln car. The kiln car is loaded with fired products. The car enters the kiln head and exits the kiln end.
Features of tunnel kiln
- Continuous production, short cycle, large output
- High heat utilization rate and fuel saving.
- Save labor.
- The kiln body and kiln furniture have long service life
Working principle of tunnel kiln
The working principle of the tunnel kiln is to complete the firing process through three zones: preheating zone, firing zone and cooling zone.
The tunnel kiln is a long and straight tunnel with fixed walls and arches on both sides and the top, and the kiln car runs on the track laid at the bottom. The high-temperature flue gas produced by combustion flows along the tunnel to the tunnel kiln or the induced draft fan, acting on the kiln head under the front chimney, gradually preheating the products entering the kiln. This section constitutes the preheating zone of the tunnel kiln. The cold air of the tunnel kiln blows into the tail of the kiln to cool the rear products. The cold air blown out is heated by the products and then extracted and sent to the drying. As the heat source for drying the biscuits, this section constitutes the cooling zone of the tunnel kiln. A sagger filled with ceramic products is placed on the trolley, which is pushed in slowly and continuously from the entrance of the preheating zone (usually mechanically), and the trolley carrying the fired products is gradually pushed out from the exit of the cooling zone (one car is pushed out after about one hour). Tunnel kilns can be used for continuous heating of steel billets or continuous sintering of ceramics.

Classification of tunnel kilns
Classification by whether the kiln body is movable
- Fixed tunnel kiln: The kiln body is constructed on a fixed foundation, the entire kiln is fixed, and the kiln car pushes the finished bricks out of the kiln during the forward movement
- Mobile tunnel kiln: The kiln body is moving, the bricks are stacked on a fixed foundation, and the kiln body moves forward while driving the fire forward
Classification by kiln roof structure
- Arch tunnel kiln: The kiln roof is built in a semicircular arch with reference to the model of the wheel kiln
- Micro-arch tunnel kiln: The distance from the arch line to the highest point is less than half of the kiln body width
- Suspended flat-top tunnel kiln: The ceiling panels are hung on the kiln piece by piece through steel hooks or refractory bricks On the steel beam at the top, an insulation layer is laid on the hanging board
Classification by stacking method
- Single stacking tunnel kiln: only stacking once from drying to roasting
- Double stacking tunnel kiln: bricks are stacked after drying or semi-drying, increasing the stacking height
Classification by the position relationship between drying kiln and roasting kiln
- Direct drying tunnel kiln: drying kiln and roasting kiln are arranged in a straight line
- Parallel tunnel kiln: drying kiln and roasting kiln are arranged separately and in parallel
Classification by kiln section width
- Small section tunnel kiln: less than 4.6 meters
- Middle section tunnel kiln: 4.6-6.9 meters
- Large section tunnel kiln: more than 6.9 meters
Tunnel kiln uses
- Metallurgy: large-scale smelting of copper, iron and other metals; manufacturing important raw materials for refractory materials such as smelting furnaces
- Construction: manufacturing bricks and tiles for building houses, city walls, tunnels and tunnels
- Irrigation: making sintered bricks and tiles for building water diversion channels
- Other fields:
Manufacturing industrial materials such as glass and ceramics
Applied to continuous heating of steel or continuous sintering of ceramics
Large-scale production of sanitary ware products and larger parts