1, tunnel kiln. So its name is incredible, and its kiln body is like a tunnel. In fact, tunnel kiln in a broad sense, including roller kiln, trolley tunnel kiln, push plate kiln and turntable kiln, all belong to the scope of tunnel kiln. Tunnel kiln in narrow sense. It only refers to trolley tunnel kiln, and tidal tunnel kiln is called push plate kiln. The pusher kiln is a fire-resistant plate directly installed on the high-temperature guide rail. (For example, the guide rail of Wang Gang brick or corundum ball can roll in situ. Due to the load-bearing thrust of fire-resistant board, it is generally not long, 20 meters long or a few meters short, and the daily output is not large. Because the propeller directly pushes the fire-resistant plate forward, it is called the push plate kiln. The pusher kiln in Chaozhou is a trolley tunnel kiln. Due to the continuous production of tunnel kiln, the heat in the preheating zone is basically supplied by the waste heat brought by the flue gas in the firing zone. Because the kiln wall is not like shuttle kiln, there is no circulating heat loss of heating and cooling, and most of the waste heat with high temperature flue gas can be used, so the energy saving effect is better than that of gap kiln. However, because the trolley still needs to be heated and then cooled, some heat is wasted, and its energy-saving effect and temperature difference are not as good as those of roller kiln.
2. Shuttle kiln. Intermittent production kiln is suitable for small batch and multi-variety production. Because of the flexibility of production, many small and medium-sized ceramic factories still use this kind of kiln. However, due to the gap type, the kiln wall and trolley absorb heat and consume energy, which is relatively high in general. However, through the kiln design and the efforts of manufacturers, such as using high-speed burners for rapid firing and using light refractory insulation materials to reduce the heat storage of the kiln, some fast-burning shuttle kilns have achieved the energy-saving effect equivalent to that of the old tunnel kilns.
3. Roller kiln. The refractory plate is directly driven by high-temperature resistant ceramic rods, and the refractory plate loaded with products is directly loaded on the rods, also known as roller kiln. The earliest imported bricks were fired on the wall without pallets, and the floor tiles were directly placed on sticks. Because the temperature difference during preheating, firing and cooling is very small, the firing time is shortened from more than ten hours in the past shuttle kiln and tunnel kiln, so it is extended to art ceramics and daily-use ceramics. With the improvement of bar quality, it gradually changes from low temperature type to medium and high temperature type. Because the roller kiln is directly supported by the fire-resistant plate on the stick rolling in place, it does not need to absorb a large part of heat with a trolley like the tunnel kiln, and its air tightness is much better than that of the tunnel kiln. Therefore, its energy-saving effect is better than that of tunnel kiln. One of its biggest defects is that the products that need high temperature reduction are of higher quality. The sintering of high temperature ceramic products within 1350℃ can be well solved by using silicon carbide rods. However, the problems of kiln glaze change and crystalline glaze firing have never been solved, because it is faster.
The general structure, advantages and disadvantages of shuttle kiln, tunnel kiln and roller kiln are analyzed above. Enterprises can choose their own kilns according to their product structure, output and economic capacity:
1. Because the daily output is less than 20m3, and there are many kinds of products and different firing temperatures, it is recommended to use the fast-burning shuttle kiln, which is difficult to meet the output of tunnel kiln.
2. If the daily output is more than 20m3, but the glaze color is complex, such as crystalline glaze kiln needs a certain constant temperature and cooling time, traditional shuttle kiln or electric shuttle kiln can be used from the perspective of kiln construction economy; If the kiln becomes glazed or crystalline glaze is only local, you can choose a fast kiln, which is not only fast but also slow. Slow, the temperature difference can be controlled very small. But the slow energy saving effect is poor.
3. At the temperature of 1300℃, it is suggested to use roller kiln or large-scale fast shuttle kiln for high-yield art ceramics, daily-use ceramics and bathroom ceramics.
4. With large output, high height, heavy weight, high temperature and single glaze color, the trolley tunnel kiln can be selected. Such as high-temperature daily-use ceramics and bathroom ceramics.
Advantages and disadvantages of electric kiln and gas kiln: Because the heating element of electric kiln does not produce smoke, only the volatiles of the blank itself are discharged during the firing process. For shuttle kiln, the kiln can be very sealed, only a few exhaust holes are needed, and no smoke brings out heat. Sintering at 1200℃ and low temperature oxidation sintering, and now the production cost is lower than that of gas kiln. According to the calculation, the electricity price is 0.8 yuan/kWh and the price of liquefied gas is 6.2 yuan/kg, which is a balance point. The continuous electrothermal roller kiln is used to burn oxidation products below 1220℃, and now the production cost is lower than that of gas roller kiln by more than 15%. But it needs a transformer of more than 200kva, and the investment is not small. Ceramic factories with excess transformer capacity can install electric heating wires near preheating zone or firing zone to preheat and heat up. Gas is still used in high temperature area, but electric kiln can't burn and reduce. Silicon-molybdenum rod is applied to heating elements above 1280℃. Silicon-molybdenum rod is easy to age and its service life will not be too long. The choice of electric heating kiln depends on the electricity price. Electric heating kiln can be selected in areas with low average electricity price. In the case of high electricity price and high liquefied gas price, it is economical to transform electric heating on the original kiln, but the original gas function should be retained.