Tunnel Kiln for Ceramic and Clay Bricks

Shaanxi Ibrick tunnel kiln for ceramic and clay bricks

China Ibrick old manual brick factory modified tunnel kiln technical supporting automatic brick machine 
Ibrick provice new advanced technology auto brick project design and technical supporting Clay brick tunnel kiln 

Productive Technology
Main equipment include: box feeder, primary roller crusher, fine pulverizing grinder, double shaft mixer, reversible belt conveyor, multi-buckets excavator, mixing and extruder, double stage vacuum extruding machine, tunnel dryer, tunnel kiln.
Sintering bricks are produced by using clays as raw material and adopting two-time setting and baking processing which is a semi-stiff extruding process.
Drying in the tunnel drying chamber and baking in the clay brick tunnel kiln 

Estimated Consumption for Materials & Power
Technological Description
For this production line, raw material is clay, finished products bricks. Big quantity of raw material is required to be treated.
In raw materials warehouse, loaders will supply raw materials to box feeders. At the upper part of materials warehouse there are metallic fences, so as to prevent masses of clay and organic matter from damaging the equipment. Raw material will be sent to primary roller crusher and fine pulverizing grinder in turn. Coal powder will be added here and mixed with water.
In order to increase the warehouse capacity and improve the ageing effect, the inclined-shaft type aging warehouse is adopted. Thus the raw material is being distributed on the top by movable belt conveyor; aged raw material will be unloaded from side edge by multi bucket excavator.
The general process is semi-stiff plastic extruding process for brick molding, tunnel dryer for drying and tunnel kiln for firing.
This is advanced and practical technology, which can meet the production requirement.

Drying and Firing
Drying and firing will adopt 2 times setting & firing process. Drying chamber adopts new type tunnel dryer with inner width of 2.52 meter. Whole production line adopts 14 lines of double-rail tunnel dryers. The heating source is residual/waste heat from the tunnel kiln. The smoking air feeding temperature and air volume will be adjusted through the air-adjustment-system, so as to ensure the drying quality of green bricks. Well-dried green bricks will be unloaded from drying cart and re-stacking on the kiln cart manually.
Tunnel kiln adopt 2 sets of large section with inner width of 4.6meter, it is designed as a flat ceiling structure with refractory bricks. Considering bricks cannot have black center and patterns, the firing fuel source is major by inner-mixing-coal, outer-casting-coal as replenish, the heat should meet the firing technology requirement. This kiln is suitable for firing products with 1300-1500KJ/Kg product.
Tunnel kiln has smoke-releasing system, recycling system, waste-heat recovery system, cooling system and pressure balancing system. This kiln has following features: large section, high yield, small section temperature difference, good heat preservation effect. Meanwhile, the kiln auto-control system is equipped to ensure that the baking heat parameters are stable, so the firing quality is guaranteed.

Determination of Thermal Engineering Equipment for Drying and Firing
According to raw material and technology process, the thermal engineering equipment for drying and firing process adopts 1 group of small section tunnel dryers & 1 piece of big section tunnel kiln.
The feature of this design is low investment, flexible production, make good use of the waste heat from tunnel kiln, and make full use of the tunnel kiln advantage. At the same time, it can reduce the consumption of energy. In addition, the small tunnel dryer and kiln with high heat use efficiency, big capacity, and advanced technology, thus enabling the investor to lower their production cost, to improve the product quality and to enhance their economic efficiency.


Tunnel Kiln System and Structure

System
The tunnel kiln has complete system of smoke discharging, cooling, waste heat releasing, pressure balancing under the kiln car, running and detecting system. Baking curve inside of the kiln will be more reasonable, production system more coordination through the adjustment of those system.
At the entrance side, there is a preparatory room, and a cut-off door between the preparatory room and the kiln preheating zone. There are entrance and exit doors at both ends of the tunnel kiln. Thus it effectively avoid entering the cold air and ensure the baking system inside not be influenced by outside.

Structure
Foundation: Tunnel kiln is with strip foundation. From bottom to up by order is plain concrete, reinforced concrete girder (railway girder)/ board (under kiln wall).

Wall: Red brick is laid for the pre-heating zone and cooling zone where the temperature is below 200ºC. The rest is adopting combined wall. The fireclay bricks will be laid on the baking zone and inner wall of insulting zone. The clay insulting bricks will be used for laying the insulting area. Meanwhile, refractory fabric felt (for the relative part of temperature curve above 600ºC) or rock wool felt will be used for stuffing and red bricks will be laid on the external wall.

Kiln roof structure:
One kiln car space remained in low temperature zone on both sides, which adopt cast-in concrete top slab. For other position, from the bottom to up in order are: refractory plate brick, refractory hanger brick, cast steel hanger, steel minor beam, and H type steel major beam. Both sides firebrick walls support the main beam's weight. Refractory fibrofelt, rock wool felt, rock wool boards are put on the refractory hander plate, which compose complex insulation layer. High temperature binder is being filled up to the gap between the boards, and is being painted on the upside of the insulating layer, thus to ensure the material's insulativity and structure's durability.

Coal casting hole:
It is with function such as following, replenish heat, debugging, observation, replenish oxygen or cooling under negative pressure, releasing heat under positive pressure etc. This is widely used for tunnel kiln process with inner fuel technology, which cannot be cut down or cancelled.

Sand seal:
Sand seal slot is being put in the kiln cart skirt board, which insulate the high temperature from outside, thus to avoid cold air sucked into kiln under negative pressure which will lower the kiln temperature, and to avoid high temperature gas go to kiln cart underside under positive pressure which will destroy the kiln cart steel structure or deform the railway.

Afterheat System
Products direct heat and afterheat system are being put on top of the tunnel kiln, temperature curve in 450-200 ºC range. Extractive afterheat occupies 80% of the total required heat for drying, heat source clean and no pollution. Through heat exchanger, except whole factory workshop heating, the rest high temperature gas is being sent into drying chamber. Direct heat is being extracted quickly and effectively, this will shorten the kiln length so that to lower the kiln construction investment.



Major Technological Parameters of Tunnel Kiln 
China Ibrick tunnel kiln for ceramic and clay bricks
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