Abstract: In the past 10 years, the production level of building glass and special glass in my country has improved rapidly. It has approached the international advanced level in terms of kiln age, output and quality, while the daily glass is far from the world advanced level. The average kiln age of building materials glass has grown from 4 to 5 years in the 1990s to about 10 years now; while the kiln age of daily glass has only increased from 3 to 4 years to the current 5 to 6 years. Leakage at the bottom of the pool is often the main form of short-term leakage, because the leakage at the bottom of the pool cannot be observed in advance and cannot be repaired.
1. The main factors causing material leakage at the bottom of the pool
1.1 The bottom of the pool is getting better and better
In order to meet the requirements of energy saving, the bottom of the pool is getting better and better. Good insulation not only helps to reduce heat loss, but also improves the unit melting rate. Coupled with more and more electric boosting at the bottom of the pool, it will cause the bottom temperature of the pool to increase greatly. In this way, the flowability of the glass is enhanced and it is easy to penetrate into the mud layer under the paving tiles.
1.2 Metal in broken glass
There are more and more broken glass used in bottle glass. If the metal impurities (such as iron) in the broken glass are not completely eliminated, it will lead to the phenomenon of downward erosion. This is because the metal impurities with low melting point become molten metal and the corrosion method is very similar to that of molten glass on the refractory material. Once molten metal or glass passes through the cracks between the bricks and touches the ramming material of the lower layer of the paving brick, it will corrode upward.
Many glass factories mistakenly believe that the erosion is caused by poor quality paving tiles. This just ignores the essence of the problem: the foaming of the ramming material is the real cause of the upward drilling erosion.
It can be seen from the above analysis that the increase in temperature at the bottom of the pool is the main factor for the increase in erosion of the pool bottom. However, from this point alone, the bottom of the pool will not be seriously affected, because the erosion resistance of the bottom tiles made of
AZS material is good enough to withstand higher temperatures. The problem is that the joints between bricks and the mud layer under the paving bricks are the weak links. In view of these two weaknesses, it is necessary to choose high-quality materials to achieve the following goals: ①The joints of the tiles on the bottom of the pool are closer to prevent the penetration of glass. ② Once the glass liquid contacts the mud layer through the brick joints, the material of the mud layer can not only effectively resist the erosion of the glass, but also does not release bubbles to cause upward erosion. ③The mud layer can move smoothly without cracks, so as to prevent the molten glass from drilling down again and play the role of a protective layer.
2. European and American bottle and tank bottom mud scheme
The age of bottle-tank kilns in Europe and the United States can generally reach more than 13 years. Most of the bottom mud materials used are ERSOL series products developed by Xipu, mainly including ERSOL50/ERSOL50C and ERSOL06/ERSOL06C. They are all made of fused AZS particles through a special process.
The particle diameter of ERSOL50 is 5mm. It is mixed with water and hardened quickly. It is used for pouring the base layer of the bottom of the pool. The thickness is about 45mm. The maximum diameter of the particles of ERSOL06 is 0.6mm, and the thickness is about 5mm when spread on ERSOL50.
At high temperatures, the glass phase will precipitate, and after the temperature continues to rise, the glass phase will crystallize, and the material will become ceramic and gradually melt into one. In this way, the entire pool bottom material is combined into a closed and inseparable whole, and there is no gap for the continuous flow of glass liquid. The following is a performance comparison between ERSOL50 series (including ERSOL50 and ERSOL50C) products and other products.
2.1 Bubble precipitation tendency
Experimental conditions: 1250°C soda lime glass. ERSOL castables have a lower foaming rate than general AZS ramming materials and far lower than zircon ramming materials.
2.2 Dynamic corrosion resistance test
Experimental condition 1: 1400°C, 48h, soda lime glass, 50cm/min; Experimental condition 2: 1400°C, 4811, soda lime glass, 300cm/min The ratio is determined by measuring the corroded volume to determine the corrosion resistance. 100 is the standard value, higher than 100 means better corrosion resistance, and lower than 100 means poor corrosion resistance. It can be seen from the two experiments that the corrosion resistance of fused zirconium corundum bricks, the corrosion resistance of ERSOL castables is 1/2 of that of fused zirconium corundum bricks, general AZS ramming materials and zircon ramming materials Only about 1/4 of the fused zirconia corundum brick. When the glass liquid penetrates into the mud layer, the ERSOL castable can still effectively resist the erosion of the glass liquid, which takes much longer than the other two materials. The life of daily glass furnaces in my country is generally not very long. The use of ERSOL may help some furnaces reach the expected kiln age even after the paving bricks are undercut.
3. It is recommended to use double-layer ERS0L50 for large, efficient and high transmittance furnaces
The bottom structure of the pool using double-layer ERSOL50 (such as 2x50mm) is: the first layer of AZS paving tiles, the second layer of ERSOL06 leveling layer, the third layer of ERSOL50 castable layer 2, and the fourth layer of ERSOL50 castable layer 1 and 5. Layer sintered AZS bricks.
The fourth layer (that is, the first layer of ERSOL castable) and the fifth layer sintered AZS have different expansion coefficients, which may cause cracks during the baking process. The second layer of ERSOL castable has the same composition as JU.K, that is, the same expansion coefficient, which can effectively protect the smooth movement of the second layer of ERSOL50 castable from cracking, prevent the penetration of glass liquid, and completely protect the pool. bottom.
4 Conclusion
The main reason for the leakage of the bottom of the daily glass furnace is that the daily glass uses more recycled cullet than the building material glass, and the insufficient input of sorting facilities can not effectively remove the metal impurities in the cullet, which will easily lead to molten glass The phenomenon of leakage and downward drilling of metal substances. Once the glass liquid contacts the ramming material, it is often caused by the uneven characteristics and quality of the ramming material to cause upward drilling and corrosion, so that the paving tiles are heated up and down and quickly eroded , It also caused the bottom of the pool to leak in a short time. ERSOL series products have extremely low porosity due to their product characteristics and pouring and tapping process, which can effectively prevent the leakage of glass liquid. The double-layer process provides extra protection for the furnace with high melting rate and high transmittance.
