The function of the glass melting furnace is to form a flame space with the breast wall and the front wall. At the same time, it can also be used as a medium for the flame to radiate and transfer heat to the material and the glass liquid, that is, absorb the heat released by the combustion of the fuel, and then radiate to the liquid surface of the glass. on. According to the length of the melting part, the big chute can be divided into several sections, generally at least 3 sections or more. During masonry, a 100-120mm expansion joint is reserved between each section of the dome, and the expansion joints at the top of the dome at the front and back gables should be wider.
The masonry is generally made of high-quality silica bricks, the shape of the bricks is wedge-shaped, the transverse joints are made of staggered joints, and the mortar joints are generally 1 to 2 mm. The service life of the big chrysanthemum determines the kiln age of the entire furnace. The weak links of the big chrysalis in use are the cavities such as temperature measuring holes and pressure measuring holes, the transverse joints of the big chrysalis bricks, the chuck heads of each section and the sides of the big chuck.碹 part. When the kiln is in normal operation, the kiln is under positive pressure, and the various cavities on the top of the kiln are easily burnt due to the fire. If the side turret is not in close contact with the steel ballast, it is easy to be washed and burned by the flame. Therefore, these places should use better refractory materials. At the same time, the sealing mud for the joints of the bricks and the outer layer of the silica bricks requires good performance, with good resistance to high temperature and alkali vapor.
1.2 Experimental method
A lift-type high-temperature furnace is used to simulate the refractory structure of the dome roof, and the sealing mud is used between the large dome silica brick and the light insulation brick, and the high-temperature sintering test is carried out under the same conditions. The specific operation is as follows: put a piece of silica brick on the bottom, apply a layer of sealing material in the middle, and cover the upper part with light insulation brick. Start heating from room temperature, keep it at 1350℃ for 10 minutes, lower it and open for observation. Then continue to raise the temperature, and observe the sintering conditions of silica bricks, lightweight insulation bricks and sealing mud at 1350°C, 1400°C, 1450°C, and 1600°C respectively.
Performance characterization: MIRA3LMH type field emission scanning electron microscope (SEM) was used to observe the microstructure of the refractory material, and the ThermoNS7 energy spectrometer (EDS) was used to test the chemical composition of the refractory material.
For sample #1, after sintering at 1350℃, the sealing compound and the upper lightweight silica brick are not bonded and can be easily removed; after sintering at 1450℃, the situation does not change significantly; after sintering at 1600℃, it can be removed , The sealing material has no obvious change, but the surface of the insulation brick has more porous holes, and the color changes from yellow to white. It shows that 1# sealing compound can withstand high temperature of 1600℃ and does not react with upper and lower bricks. Insulation bricks have holes due to the high impurity content of lightweight insulation bricks (93.35% of SiO2, 2.82% of Al2O3, 2.75% of CaO and 1.09% of Fe2O3). They are generally used on the outside of glass melting furnaces and the temperature is below 1400°C. However, this experiment was directly in a high-temperature furnace. After a high temperature of 1600℃, iron oxide, calcium oxide and silicon oxide formed a eutectic and diffused along the pores. The insulation brick itself had higher pores, so the pores increased.
It can be seen from Figure 2 that the 2# sealing material is sintered into a block after being subjected to a high temperature of 1600℃, but it is easy to fall off from the silica brick and the thermal insulation brick, and does not react with the two, indicating that the 2# sealing material can also withstand the high temperature of 1600℃. And it will not affect the large siliceous bricks and the upper insulation bricks.
For the 3# sample, after sintering at 1350℃, the sealing material and the upper layer of lightweight silica brick are bonded and cannot be uncovered. When the temperature is 1400℃, the sealing mud will appear molten glass on the side of the silica brick, and it will be bonded with the upper and lower silica bricks and cannot be uncovered. At 1450℃, it is obvious that the molten glass body at the edge disappears, and the molten glass body of the sealing mud penetrates into the inside of the silica brick and bonds with the silica brick, showing a eutectic phenomenon. At 1600°C, the sealing mud material completely melts and penetrates into the silica bricks (mostly into the light silica bricks, a small part into the large-sized silica bricks), melts and reacts with the silica bricks, and corrodes the silica bricks.
3# After sintering at a high temperature of 1600℃, some anorthites (area marked 1 and 2) are formed, which are associated with residual quartz (area 3); the EDS analysis results are shown in Figure 5 and Table 2, and 3# is obviously infiltrated into the silica brick. Sealing material composition. This is because the melting temperature of 3# sealing compound is relatively low. The phase diagram shows that eutectic is formed at 1300℃, so the test shows that it will bond with the upper and lower refractory materials after sintering at 1350℃. Therefore, the 3# sealing compound cannot be used for glass melting furnace bulges, otherwise it may cause corrosion to the silica bricks, reduce the life of the bulges, and at the same time form stones and furuncles in the glass, which will affect the quality of the glass.
3 conclusion
Through the high temperature sintering test, it is concluded that the silicon and aluminum silicon sealing compound can withstand the high temperature of 1600 ℃, and does not react with the large silica bricks and insulation bricks, while the aluminum silicon sealing compound introduced with calcium oxide is at 1350 ℃ The phenomenon of sintering and melting into a glass body occurs. After a high temperature of 1600°C, all of it penetrates into the contacted refractory material, which will further corrode the brick body and form defects in the glass, so it cannot be used for sealing of the large stone.
