For a large float line, the glass furnace is usually composed of an L-shaped hanging wall (usually using silica bricks), a melting part (the area in direct contact with the glass liquid should use electric fused bricks, and the top part should use silica bricks or electric furnaces). Fused bricks), neck (usually using silica bricks), cooling part including ear pool (corundum materials are usually used in places that are in direct contact with molten glass, and silica bricks or corundum are used in places that are not in direct contact with molten glass), annealing kiln, Regenerator (composed of high alumina bricks, clay bricks, direct bonded magnesia chrome bricks) and other parts.1. Hanging top
The roof of the melting part and cooling part of the glass melting furnace (including the arch angle), these parts are at a working temperature of 1600 ° C, the refractory materials used in these parts must not only be able to withstand high temperature and load, but also withstand alkali steam and batch materials Therefore, the refractory material used as the top must have extremely high refractoriness, high load softening temperature and good creep resistance, and the thermal conductivity is small, and the refractory material at high temperature cannot contaminate the glass liquid. The bulk density should also be small, and the high temperature strength is good.
The high-performance high-quality high-purity silica bricks just have the above characteristics:
a. The high load temperature is close to its refractoriness;
b. Good stability at high temperature and high compressive strength;
c. Since the main component is SiO2, the content is > 96%, which is the same as the main element composition of glass, so the erosive substances under high temperature conditions will basically not pollute the molten glass;
d. The price is cheap.
Therefore, high-purity and high-quality silica bricks have become the first choice in the production process of various glass bridges.
The chemical erosion caused by the high-temperature chemical reaction between waste materials and alkali vapor and refractory materials, as well as the crystal transformation and structural compactness changes due to phase migration and temperature are the main reasons for the damage of crown bricks.
The research results show that the alteration process of the high-quality glass kiln silica bricks used for the top of the kiln is basically caused by the migration of impurities and phase transformation of impurities, and the chemical erosion and melting effects can basically be ignored. The function of phase change and self-purification makes the kiln operation belt gradually change its performance, and its high temperature performance is improved.
2, Pond Wall
1) Parts in contact with glass liquid
The part of the melting part and the cooling part that is in direct contact with the molten glass is subject to high temperature, chemical erosion caused by the molten glass and mechanical and physical erosion caused by the flow. The most important condition for this part of the refractory material is to have good corrosion resistance to the molten glass. At the same time, the glass liquid cannot be polluted.
Fused zirconia corundum bricks, α-β corundum bricks, and β corundum bricks are commonly used outside domestic glass furnaces. Fused zirconia corundum bricks have excellent performance in high temperature and resistance to glass liquid, which is the very good erosion resistance of sintered refractory materials. The eutectic of badley zircon and α-Al2O3, so it is used as a glass kiln Furnace melting section pool wall tiles are very suitable.
The main crystal phase of α-β corundum bricks and β corundum bricks is corundum, and the glass phase content is only 1%-2%, which has good corrosion resistance. Compared with the performance of fused zirconia corundum bricks, since they do not contain ZrO2 crystals , the viscosity of the reaction layer is small, and it is not stable at high temperature, so the diffusion speed between the surface of the brick and the glass liquid is relatively large, and the kiln lining is damaged quickly. However, when the operating temperature of the kiln is lower than 1350 ° C, the corrosion resistance of a-β corundum bricks and β corundum bricks is better than that of fused zirconia corundum bricks. Therefore, a-β corundum bricks and β corundum bricks are ideal refractory materials for cooling parts and other parts when the temperature is lower than 1350 °C.
2) Parts not in direct contact with glass liquid
The part of the pool wall of the melting part and the cooling part that is not in direct contact with the molten glass (also called the breast wall) is mainly subjected to the erosion of alkali vapor and batch materials. According to different designs, some are made of corundum, and some are made of silicon. Brick, both materials can meet the requirements. Therefore, hook bricks and straight bricks are often used in this part.
3. Regenerator
1) Regenerator wall and side walls
The inner surface of the regenerator and the side wall are eroded by high temperature, dust and alkali vapor. From top to bottom, the degree of erosion gradually weakens. It is determined by the temperature and the degree of erosion. Silica bricks are generally used for the top and side walls, and low-porosity clay bricks and high-alumina bricks are generally recommended for the middle side walls; general clay bricks and low-porosity clay bricks are generally used for the lower part of the kiln. Depending on the design, in recent years, the upper part of the side wall generally adopts ordinary magnesia-chrome bricks and directly combined magnesia-chrome bricks, and alkaline bricks such as magnesia-aluminum bricks have also achieved good results.
2) Lattice
Because all the bricks of the lattice body are under the action of high temperature load, dust and alkali vapor, the degree of erosion will be more severe than that of the side wall, so the service conditions are more severe. The blockage and collapse of the lattice body is often one of the important reasons for the shutdown and cold repair of the glass kiln. Therefore, the lattice refractory material is required to have high physical strength, low creep rate, strong defense ability against alkali erosion due to changes in kiln temperature and atmosphere, no dust adhesion, and slow damage speed.
On the top of the lattice body: the temperature is the highest, which can reach 1400-1540 ° C, and it is also most severely eroded by alkali steam and dust. Generally, fused and rebonded magnesia bricks are used. Since the silicate in the fused rebonded magnesia bricks is relatively small, the periclase crystals have grown up, and a direct bond has been formed between the periclase crystals, which delays and stops the gradual increase of the periclase crystals under the action of alkali steam. Speed, not easy to crack and pulverize bricks.
The upper part of the lattice body: the temperature here can reach 1100-1430 ℃, and it is generally enough to use 95# combined with magnesia bricks.
The middle part of the lattice body: the temperature is 800-1100°C, and the alkali metal sulfate condenses in the range of 800-1100°C. The magnesium and calcium lattices are severely eroded by SO3 and Na2O and undergo chemical reactions, which will lead to larger bricks. The body expands and is seriously damaged, so this part is not suitable for using magnesia bricks, but magnesia-aluminum spinel bricks or directly combined with magnesia-chrome bricks or magnesia-zirconia bricks and magnesia olivine bricks.
The lower part of the lattice body: this section has low operating temperature, heavy load, and little erosion by alkali, but it is relatively close to the flue and directly affected by cold air. The required materials should be able to withstand rapid cooling and rapid heating, and the price should be low. Therefore, low-porosity clay bricks with relatively low prices are generally used.
