Reasonable matching of refractory materials in glass wool melting furnaces is the key to achieving high efficiency. Of course, the selection of refractory materials requires comprehensive consideration of factors such as kiln age, investment, current status of refractory materials, and production cycles to ensure the most effective and economical melting operation.
The design principle of the furnace refractory materials is: within a kiln period, strive to make the erosion of the refractory materials in all parts of the furnace basically synchronized.
The analysis of refractory material configuration in each part is as follows 4.
(1) Melting part pool wall
Since the melting temperature is low, generally below 1400°C, and the viscosity of the glass liquid is large and the reaction diffusivity is small, the erosion of the pool wall is small. Generally, 33# oxidation method fused zirconium corundum bricks can be used. For cross-flame melting furnaces, in order to achieve a longer kiln life, the melting section wall needs to use chromium-zirconium corundum bricks with a chromium content of 30%. No matter what kind of refractory material is used, there is no insulation near the liquid level line of the pool wall, and air blowing is used for cooling to extend the service life of the pool wall.
(2) Molten breast wall
The breast wall of the melting part is in the flame space of the furnace. Due to the action of high-temperature hot air flow, a large amount of alkali and boron volatiles adhere to the surface and gaps of the breast wall bricks, causing chemical reactions with the breast wall bricks to cause erosion. Therefore, breast wall tiles generally choose neutral refractory materials or alkaline refractory materials with stable high-temperature chemical properties and resistance to alkali and boron. For breast walls with a low kiln age, 33#fused zirconium corundum bricks are the best choice, but for breast walls with a long kiln age, sintered zircon bricks or chromium zirconium corundum bricks with a chromium content of 30% are better.
(3) Melting part pool bottom paving tiles
Since the heat dissipation area at the bottom of the pool in the melting part is large, in addition to strengthening the thermal insulation, the increased corrosion caused by the increase in temperature at the bottom of the pool due to thermal insulation must also be considered. Fused zirconium corundum brick paving is the first choice for the bottom of glass wool furnaces. For most glass wool furnaces, the stable performance of this material is fully matched with the life of the furnace.
When the depth of the molten glass in the furnace is less than 500mm and bubbling is used, the high temperature of the molten glass at the bottom of the tank and the strong convection of the molten glass produced by bubbling greatly intensify the mechanical erosion and erosion of the refractory materials at the bottom of the tank by the molten glass. If The traditional fused zirconium corundum brick paving layer is difficult to meet the long kiln age (more than 5 years), so it is more appropriate to choose chromium zirconium corundum bricks containing 15% chromium.
(4) Dayi of the Melting Department
For horseshoe flame glass wool melting furnaces, silica bricks are mostly used for the roof. Although alkaline bricks are suitable for alkaline glass liquid, silica bricks are cheap and have poor resistance to alkaline vapor erosion. Due to the high boron and alkali content in the glass wool, when the glass axis on the brick surface is lost, the silica bricks are easily eroded under the action of boron and alkali vapor, thus affecting the life of the furnace.
At present, the silica brick roof of the domestic horse-shoe flame glass wool melting furnace usually develops rat holes after 9 months to 1 year, which requires regular maintenance and repairs and can barely last 3 years. Repairing the roof is not only a arduous hot repair operation, but also has an impact on production. To obtain a kiln life of more than 5 years, the roof material of the glass wool furnace is not suitable for silica bricks. Instead, chromium zirconium corundum bricks containing 30% chromium or special sintered mullite bricks should be used.
(5)Liquid hole
The liquid hole is the most easily eroded part of the glass wool melting furnace and cannot be repaired in a hot state. Therefore, the service life of the refractory material in the liquid hole directly determines the life of the furnace.
At present, most glass wool melting furnaces use 41# non-shrinkage fused zirconium corundum bricks for the liquid flow holes. Since the temperature of the glass liquid in the glass wool melting furnace is relatively low, generally below 1250°C, the erosion of the refractory material in the liquid hole is mainly caused by mechanical erosion. For glass wool melting furnaces with small tonnage, 41# non-shrinkage fused zirconium corundum bricks can fully meet the requirements of the kiln age. However, for glass wool melting furnaces with large tonnage and long kiln age, the liquid cave bricks should be made with 50% chromium content. Chromium zirconium corundum bricks will be more reasonable.
(6) Checkered bricks
Glass wool contains high alkali and low boron, which corrodes magnesia bricks severely. Moreover, alkali vapor and boron vapor are easy to crystallize in the medium temperature range (810~940°C). The crystallization material has a high viscosity and adheres to the uneven surface of the lattice bricks after erosion, thus causing blockage of the lattice bricks.
At present, the checker bricks of glass wool melting furnaces generally use alkaline bricks, the upper layer is 97 magnesia bricks or 98 magnesia bricks, the middle layer is 95 magnesia bricks or 96 magnesia bricks, and the lower layer is magnesia bricks and low-pore clay bricks. The cost of the checker bricks configured in this way is low, but because alkali and boron vapor crystallize and adhere to the checker bricks, the checker bricks need to be replaced after about one and a half years of use. For checker bricks with long kiln life, cross-shaped electric flame zirconium corundum bricks are the first choice.
(7)Access
For the upper structure of the flame kiln passage, 33# fused cast azs bricks or sintered zircon bricks are generally used. For the upper structure of the electric furnace passage, sintered mullite bricks can be used.
The path in contact with the glass liquid can be made of 33# fused zirconium corundum bricks or chromium zirconium corundum bricks containing 30% chromium.
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