In the glass industry, refractory materials are the material conditions of glass kilns and have a great impact on the overall efficiency of the kiln. Glass kiln refractory materials are the first of the key factors affecting the return rate of glass melting furnace projects, and are also the key to ensuring the performance and stable operation of glass melting furnaces. Glass kiln refractory materials are not only used in large quantities, such as a 500t/d float glass melting furnace, which requires about 5,000t of refractory materials, but also account for a large proportion of the total kiln project cost and even the entire factory project investment, so it is necessary to select materials rationally.
How to choose refractory bricks for glass furnace?
The guiding ideology of glass furnace refractory selection is to take into account the technical and economic factors. Based on the physical and chemical properties, structural mode and critical performance indicators of refractory materials, working air quality parameters of each position of the furnace and the corrosion principle and mutual reaction of materials at high temperature, the detailed knowledge and practical experience of the actual operation characteristics of relevant furnaces and refractory materials are combined to select and effectively match the refractory materials at each position of the melting furnace, so as to achieve the best application effect of increasing the service life and reducing the construction cost. The actual requirements are given.
① Consider the necessary performance indicators, such as high temperature characteristics, chemical stability, heat resistance, volume stability and impact toughness
② No pollution to the glass liquid, little impact on the quality of the glass liquid.
③As long as possible.
④ There is no contact reaction between the refractory materials of different materials laid together at high temperature,
⑤ Minimize the amount of materials and heat dissipation damage.
⑥ Use high-quality materials for vulnerable parts, and ordinary materials for other parts to ensure "effective matching and synchronous kiln age".
The basic thermal repair methods for refractory materials used in tempered glass factories mainly include the following.
(1) Thermal repair of side wall bricks
After the side wall is built with molten 41#AZ5 bricks, it can meet the service life requirements of the melting furnace. The amount of thermal repair work is very small. At present, the two methods of thermal repair of side wall bricks that will be used are given below.
① Cooling circulating water pipe method.
Use a seamless pipe with a diameter of 20~50mm, and immerse it along the corroded wall 50~80mm below the inner liquid level of the kiln, so that the surrounding glass liquid condenses and the outlet water temperature is maintained at around 50℃. Although the two methods are effective, they increase heat and water consumption, and can only be used on the upper end of the side wall. When most of the bricks are corroded, they will not work.
② External iron brick method.
When the side wall bricks are corroded to only 30mm thick, a 150mmS homogeneous brick material (also called iron-binding brick) can be pasted on the outside. Old bricks can be used for external tiles, and they must be heated to about 80℃. The surface between bricks should be as flat as possible, and the brick joints should be small.
(2) Thermal repair of heat storage room grid bricks .
Because of the use of magnesia-chrome bricks, magnesia bricks, high-quality high-purity zirconium corundum bricks, etc. with strong adhesion of alkali-resistant primers, the heat storage room grid bricks can be used for one kiln period. At present, the main problem of the heat storage room is the blockage of the grid body after the granular material is melted into nodules. The main idea of the heat storage room thermal repair is to maintain the smooth flow of the grid body. The method of eliminating the nodules of granular materials in the heat storage room mainly adopts mechanical removal method, flame melting removal method (reverse burning method), etc.
(3) Thermal repair of nozzle bricks .
Nozzle bricks are special-shaped bricks used in gasoline and diesel melting furnaces. This is a safe passage for the heavy oil ejected by the spray gun to enter the kiln and mix with the combustion gas. Since the nozzle brick is located at the blasting port, it is easy to be burned if it is directly exposed to the flame. When the nozzle brick's blasting port is burned and cracked, it should be replaced. The replacement method is relatively simple, that is, first take out the spray gun, open the small gap on the nozzle brick, take out the old nozzle brick, heat it (placed next to the small furnace for baking) or heat it to about 900℃ according to the brick usage, replace it with the original position, smooth the gap, install the spray gun, and restore its posture, and the hot repair is completed.
The traditional hot repair method is harsh and labor-intensive. The use of high-grade refractory materials has been alleviated a lot, but it is still a relatively difficult and complicated work, which interferes with normal production. The current hot patching and hot oxygen spraying can improve the standard of hot repair, which is safer for personnel and equipment, and has been promoted and adopted.
Hot patching is suitable for reinforcing the structure of refractory materials that are damaged in the late stage of the melting furnace, or blocking holes, etc., which may pollute the glass liquid and affect the normal operation of the melting furnace. The hot oxygen spraying method is a method of repairing the refractory materials by spraying similar refractory particles to the refractory to be repaired, causing it to self-melt and weld at high temperature. The hot oxygen method can quickly and safely perform hot repairs on refractory materials. It is very effective not only for general damaged and damaged refractory materials, but also for refractories that are moved or accidentally broken, and even for locations such as filling or plugging holes that cannot be done by traditional hot patching methods. This method is conducive to improving the efficiency of melting and sealing.
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