Tunnel kiln is a modern continuous firing thermal equipment, widely used in the production of ceramic products baking, in the abrasive and other metallurgical industries. Among them, the latest type of tunnel kiln designed by the Russian Leningrad place, more advanced.
Tunnel kilns began in 1765, when only ceramic glazes could be fired, and by 1810, there were ones that could be used to fire bricks or pottery, and from 1906 onwards, they were used to fire porcelain tiles. The first famous tunnel kiln, the Fauquieren type, was gradually improved in many ways after 1910.
The tunnel kiln is generally a long, rectilinear tunnel with fixed walls and vaults on the sides and top, and kiln cars running on tracks laid at the bottom. Combustion equipment located in the middle of the tunnel kiln on both sides, constituting a fixed high-temperature zone - firing zone, combustion of high-temperature flue gas produced in the tunnel kiln front chimney or induced draft fan under the action of the tunnel kiln along the tunnel to the head of the kiln direction of the flow, and at the same time gradually preheat into the kiln of the products, this section constitutes the tunnel kiln pre-tropical band. In the end of the tunnel kiln into the cold air, cooling tunnel kiln products in the latter part of the drum into the cold air flow through the products and be heated, and then pumped into the dryer as a heat source for drying billet, this section constitutes the cooling zone of the tunnel kiln.
Place the sagger loaded with ceramic products on the trolley, continuously from the entrance of the pre-tropical slowly pushed into (commonly used mechanical push), while the cart containing the burnt product is gradually pushed out by the exit of the cooling belt (about 1 hour, push out a car).
Applied to continuous heating of steel billets, or continuous sintering of ceramics.
Tunnel kilns have a range of advantages over the old intermittent inverted flame kilns.
Tunnel kiln began in 1765, when only ceramic glaze can be fired, to 1810, there can be used to fire brick or pottery, from 1906 onwards, only used to fire porcelain tires. The first famous tunnel kiln, the Fauquieren type, was gradually improved in many ways after 1910.
The tunnel kiln is generally a long rectilinear tunnel with fixed walls and vaults on the sides and top, and kiln cars running on tracks laid at the bottom. Combustion equipment located in the middle of the tunnel kiln on both sides, constituting a fixed high-temperature zone - firing zone, combustion of high-temperature flue gas produced in the tunnel kiln front chimney or induced draft fan under the action of the tunnel kiln along the tunnel to the head of the kiln direction of the flow, and at the same time gradually preheat into the kiln of the products, this section constitutes the tunnel kiln pre-tropical band. In the end of the tunnel kiln into the cold air, cooling tunnel kiln products in the latter part of the drum into the cold air flow through the products and be heated, and then pumped into the dryer as a heat source for drying billet, this section constitutes the cooling zone of the tunnel kiln.
Place the sagger loaded with ceramic products on the trolley, continuously from the entrance of the pre-tropical slowly pushed into (commonly used mechanical push), while the cart containing the burnt product is gradually pushed out by the exit of the cooling belt (about 1 hour, push out a car).
Applied to continuous heating of steel billets, or continuous sintering of ceramics.
Tunnel kiln has a series of advantages compared with the old inverted flame kiln of intermittent type.
1. Continuous production, short cycle, high output and high quality.
2. The use of countercurrent principle of work, so the heat utilization rate is high, fuel economy, because the heat retention and waste heat utilization are very good, so the fuel is very save, compared with the inverted flame kiln can save fuel about 50-60%.
3.The firing time is shortened, compared with the ordinary kiln from the kiln to empty need 3-5 days, while the tunnel kiln can be completed in about 20 hours.
4.Saving labor. Not only is it easy to operate when firing, but also the operation of loading and discharging the kiln are carried out outside the kiln, which is also very convenient and improves the labor conditions of the operators and reduces the labor intensity.
5.Improve the quality. Pre-tropical band, firing belt, cooling belt temperature of the three parts, often maintain a certain range, easy to grasp the firing law, so the quality is also better, less breakage rate.
6. Kiln and kiln furniture are durable. Because the kiln is not subject to rapid cooling and heating, so the kiln has a long service life, generally 5-7 years before repair.
However, tunnel kiln construction requires more materials and equipment, so a larger investment. Because it is a continuous firing kiln, so the firing system should not be changed at will, generally only applicable to the production of large quantities and the firing system requires basically the same products, less flexible.
III. Disadvantages
1.Its tunnel kiln construction requires more materials and equipment, so a larger investment;
2.For different products must be a comprehensive change in the roasting process system; production technology requirements are stringent; kiln car easy to damage, maintenance workload and so on.
Energy-saving way
As the tunnel kiln is a continuous kiln, heat utilization is better, and most of the tunnel kiln using the combustion air taken from the natural air or in the cooling belt blowing into the cold air, so that the air becomes hot. Although the waste heat is utilized, but because the extracted hot air, mixed with a very large number of high-temperature belt combustion of exhaust gases, so leading to insufficient oxygen in the combustion air, combustion effect is poor. The hot air exchanged by using a heat exchanger is fresh hot air, which can achieve the best combustion effect. If you use a metal heat exchanger, part of the waste heat recovery can be carried out, but if the temperature of the cooling belt reaches 800 degrees or more, the metal heat exchanger is very easy to be damaged by the high temperature.
The use of ceramic heat exchanger can solve this problem, ceramic heat exchanger has the following characteristics:
1. Put the ceramic heat exchanger in the tunnel kiln cooling belt, the use of products on the waste heat to preheat the air, can preheat the fresh air to about 300-600 degrees Celsius, the hot air to the high-temperature belt burner, do combustion air, can achieve the purpose of energy saving.
2. Long service life, installed once can be used for more than 5 years.
3.The use of direct and simple, temperature balance, one-time investment is less, save energy.
Operation method
First, change the billet palletizing form, add the head in the middle and lower part, reduce the aperture, and lower the height of the kang leg. This measure is especially applicable to the case where the yarding method is not changed with the seasonal changes, and it is especially applicable to the manufacturers who still use the high kang leg in summer in winter.
Second, reduce the height of the use of the near gate, so that the bottom of the heat preservation belt cooling rate slower.
Third, extend the temperature preservation belt appropriately, and extend the distance and time of air supply.
Fourth, if the amount of cold air into the amount is too large, so that the insulation belt cooling cooling too fast, you can reduce the amount of cold air into the amount of cold air, reduce the cooling cooling rate of the insulation belt.
Fifth, a small amount of hard to add, heavy burning after the fire. Or through the eye of the fire in the first row of temperature preservation belt before the addition of ash "blocking the back wind".