In the glass tank kiln, the refractory material is in direct contact with the molten glass, batch materials and their volatiles (mainly: alkali metal oxides, namely alkali vapor, borides, fluorides, chlorides, sulfur compounds, etc.), so they are corroded In order to reduce the number of brick joints, the glass pool kiln is mostly built with large bricks (referred to as: glass kiln large bricks), and the brick joints are also blocked with refractory mud with similar refractoriness. In addition to high enough refractoriness, softening temperature under load, and mechanical strength, refractory materials for glass tank kilns should also have strong erosion resistance (slag resistance), excellent rapid cooling and rapid heating resistance (thermal shock resistance). sex). Usually glass is alkaline, so glass kilns generally use alkaline, neutral or weakly acidic refractories with strong alkali corrosion resistance (for the production of low-alkali glass and alkali-free glass, this condition can be appropriately relaxed).
The principles of refractory materials for glass pool kilns are as follows:
①Select refractory materials reasonably according to the type of kiln and the working characteristics of each part of the kiln body.
Different types of glass kilns, different specific parts of the kiln body, and different damage mechanisms and damage degrees of refractory materials. Therefore, the refractory materials selected for the glass tank kiln should be adapted to the working characteristics of their parts, and strive to "use materials on demand", that is, use high-quality materials for key parts and general materials for secondary parts, so as to achieve "reasonable matching, and kiln age." Synchronize".
②Select the corresponding refractory material according to the glass composition
The refractory material in contact with the glass liquid will be damaged by the erosion of the glass liquid, and the damaged refractory material will contaminate the glass liquid. The particles of the refractory material in the flame space and the eroded droplets of the refractory material will also pollute the glass liquid if they fall into the glass liquid. glass liquid. Refractory materials with different compositions have different degrees of pollution to the glass liquid after being eroded, so the corresponding refractory materials should be selected according to the glass composition. For example, for ordinary soda-lime-silica glass, alkali erosion is the main cause of damage to the refractory material. Therefore, the part of the kiln that is in contact with the glass liquid phase should use alkali-resistant refractory bricks, such as fused zirconium corundum bricks. Of course, the refractory material is gradually eroded during the glass melting process, so a small amount of erosive material is allowed to dissolve evenly in the glass liquid to avoid defects such as stones, streaks and bubbles.
③Select refractory materials according to the performance of refractory materials
Although not all parts of the glass kiln must use the highest quality refractory materials, the performance of the refractory materials must be able to meet the requirements of its use. Generally speaking, the refractory materials used in glass tank kilns should have high corrosion resistance and high load softening temperature under the operating temperature and other permitted conditions. For example, magnesia brick is a typical alkali However, it is not suitable as a refractory for glass tank kilns because of its low softening temperature under load. The refractory material of the glass pool kiln should also have good thermal shock resistance to avoid cracking due to temperature fluctuations. This problem should be paid special attention to when selecting the refractory material in the regenerative chamber and the refractory material for the flame space. Regarding the high temperature volume stability of refractory materials, it is necessary to avoid reburning shrinkage refractory materials as much as possible to prevent the brick joints from being too large due to high temperature shrinkage of refractory bricks.
④Select batch-produced refractories as much as possible
Mass-produced refractory materials are of relatively balanced quality and relatively low price. In addition, when selecting refractory bricks, attention should be paid to the correct shape to minimize their processing, which is also conducive to improving the integrity of the masonry and reducing the brick joints.
⑤To avoid contact reaction between refractory materials of different materials
The contact reaction between refractory bricks of different materials will gradually damage the masonry of the glass pool kiln, so there should be no contact reaction between adjacent refractory materials, which should also be paid enough attention.
Since the fused refractory material of Al2O3-ZrO2-SiO2 system (ie fused zirconium corundum brick, referred to as: fused AZS brick, but pay attention: the brick will peel off due to crystal transformation at 1000 ~ 1200 ℃), the electric fused Melting refractories occupy an increasing proportion in glass furnaces, which makes refractories for glass furnaces develop towards the use of high-quality raw materials and high-quality craftsmanship. As a result, the performance of refractory materials for glass tank kilns has been greatly improved, thereby creating good conditions for improving the glass melting process and kiln structure and improving the quality of glass liquid.
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