Reasonable matching of refractory materials in glass wool furnace is the key to high efficiency. Of course, the selection of refractory materials needs to comprehensively consider factors such as kiln age, investment, refractory material status, and production cycle to make the operation of the furnace the most effective and economical.
The design principle of the refractory material of the melting furnace is: within a kiln period, strive to make the erosion of the refractory materials of all parts of the furnace basically synchronized. This is the most economical and reasonable.
The configuration analysis of refractory materials in each part is as follows:
(1) Pool wall of melting part
Because the melting temperature is low, generally below 1400 ℃, and the viscosity of the molten glass is large, the reaction diffusion rate is small, so the erosion of the pool wall is small. Generally, 33# oxidation method fused zirconia corundum bricks can be used. For the horizontal flame furnace, in order to achieve a longer kiln life, the wall of the melting part needs to use chromium AZS bricks with a chromium content of 30%. No matter what kind of refractory material is used, no insulation is done near the liquid level line of the pool wall, and air cooling is used to extend the service life of the pool wall.
(2) Breast wall of melting part
The breast wall of the melting part is located in the flame space of the furnace. Due to the high temperature and hot air flow, a large amount of alkali and boron volatiles adhere to the surface and gaps of the breast wall tiles, and chemically react with the breast wall tiles to cause corrosion. Therefore, breast wall bricks generally choose neutral or alkaline refractory materials with stable high temperature chemical properties and resistance to alkali and boron. For the breast wall of low kiln age, 33# fused AZS brick is the best choice, but for the breast wall of long kiln age, sintered zircon brick or chromium AZS brick with 30% chromium content is better.
(3) Paving tiles at the bottom of the melting pool
Due to the large heat dissipation area at the bottom of the melting part, in addition to strengthening the heat preservation, it is also necessary to consider the increased erosion caused by the increase of the bottom temperature caused by the heat preservation. Fused AZS brick pavement is the first choice for the bottom of glass wool furnaces. For most glass wool furnaces, the stability of this material matches the life of the furnace.
When the molten glass depth of the melting furnace is less than 500mm and bubbling is used, the high temperature of the molten glass at the bottom of the pool and the strong convection of the molten glass produced by the bubbling greatly aggravate the mechanical erosion and erosion of the molten glass on the refractory materials at the bottom of the pool. The use of traditional fused zirconia corundum brick paving layer is difficult to meet the long kiln age (over 5 years), so it is more suitable to choose chromium AZS brick with 15% chromium.
(4) The melting part
For the horseshoe flame glass wool furnace, most of the ceiling is made of silica brick. Although alkaline bricks are suitable for alkaline glass solution, silica bricks are cheap and have poor corrosion resistance to alkaline vapor. Due to the high content of boron and alkali in the glass wool components, when the glass glaze on the surface of the brick is lost, under the action of boron and alkali vapor, the silicon brick is easily eroded, thereby affecting the life of the furnace.
At present, the silicon brick roof of the domestic horseshoe flame glass wool furnace generally produces rat holes after 9 months to 1 year, which requires frequent maintenance and repair, which can barely last for 3 years. Repairing the dome roof is not only a heavy hot repair work, but also has an impact on production. To obtain a kiln age of more than 5 years, the roof material of the glass wool furnace is not suitable for silica bricks. Instead, chromium AZS bricks containing 30% chromium or special sintered mullite bricks should be used.
(5) Liquid hole
Liuyedong is the most eroded part of the glass wool melting furnace and cannot be repaired in a hot state. Therefore, the service life of the refractory material of the flowdong directly determines the life of the furnace.
At present, most of the flow holes of glass wool furnaces use 41# non-shrinkage fused zirconia corundum bricks. Because the temperature of the molten glass in the glass wool furnace is relatively low, generally below 1250°C, the erosion of the refractory materials in the liquid cave is mainly mechanical erosion. For small-tonnage glass wool kilns, 41# non-shrinkage fused AZS bricks can fully meet the requirements of the kiln age, but for large-tonnage and long kiln-year glass wool kilns, the flow hole bricks use 50% chromium. The chromium AZS brick will be more reasonable.
(6) Checker brick
The composition of glass wool contains high alkali and low boron, which can erode the magnesia bricks severely. In addition, alkali vapor and boron vapor are easy to crystallize in the middle temperature region (810~940℃), and the crystallized product has a high viscosity and adheres to the uneven surface of the checker brick after corrosion, which causes the checker brick to block.
At present, the checker bricks of glass wool furnace generally use alkaline bricks, the upper layer is 97 magnesia brick or 98 magnesia brick, the middle layer is 95 magnesia brick or 96 magnesia brick, the lower layer is magnesia chrome brick and low-porosity clay brick. The cost of the checker bricks configured in this way is relatively low, but the checker bricks need to be replaced after using for about one and a half years because the alkali and boron vapor crystallize and adhere to the checker bricks. For checker bricks with long kiln age, cross-shaped fused zirconia corundum bricks are the first choice.
(7) Access
For the upper structure of the flame kiln passage, 33# fused 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 passage in contact with the molten glass can be 33# fused zirconia corundum brick or chromium AZS brick with 30% chromium.
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