Three major thermal equipment for glass production
Take float glass as an example, the three major thermal equipment for glass production include float glass melting furnace, float glass tin bath and glass annealing furnace.
In the production process of glass, the glass melting furnace is responsible for melting the batch into glass liquid and clarifying, homogenizing and cooling it to the temperature required for molding.
The tin bath is the key equipment for glass molding. The glass liquid with a temperature of 1050~1100℃ flows from the flow channel to the tin liquid surface in the tin bath. The glass liquid is flattened and polished on the surface of the tin bath, and is controlled by mechanical pulling, sidewalls and edge drawing machines to form a glass ribbon of the required width and thickness. And it leaves the tin bath when it gradually cools to 600℃ during the forward process.
The function of the annealing furnace is to eliminate the residual stress and optical inhomogeneity of float glass, and to stabilize the internal structure of the glass. The continuous glass ribbon with a temperature of about 600℃ caused by the tin bath enters the annealing furnace through the transition roller table.
Refractory materials are required in all three thermal equipments. The following 9 types of refractory products are commonly used in glass melting furnaces:
01 Silica bricks for glass melting furnaces
Silica bricks for glass melting furnaces refer to siliceous refractory products used in the high-temperature parts of glass tank furnaces (not in contact with glass liquid). Tank furnaces are complex and large masonry built with various refractory materials. Its vaults are mostly made of silica bricks, and breast walls and small furnaces were also all made of silica bricks. Some glass kilns also use silica bricks for the vaults and checker bricks of the heat storage chambers. Silica bricks do not pollute the glass liquid. The main component of silica bricks is SiO2. If there are falling blocks or surface droplets during use, it will not affect the quality of the glass liquid. The appearance of the product should be regular, and the dimensional deviation should not be greater than ±1% of the design value. The taper of the wedge brick should be accurate. Cracks with a width greater than 0.5mm and cooling cracks caused by improper cooling are not allowed. The length of cracks on the working surface and non-working surface should be limited respectively. The distortion of the brick surface is not more than 0.5% of the length of the brick
02 Clay bricks for glass kilns
Clay refractory bricks are weakly acidic refractory materials. During the high-temperature calcination process, the microstructure inside the clay brick changes, forming a dense crystal, which has high refractoriness, high strength and good corrosion resistance. . The characteristics of clay bricks are mainly reflected in their high refractoriness, good thermal stability and low thermal conductivity. This enables clay bricks to withstand long-term operation in high-temperature environments and maintain structural stability and integrity. At the same time, the low thermal conductivity of clay bricks helps to reduce heat loss inside the kiln and improve thermal efficiency.
03 High-alumina bricks for glass kilns
When used in glass kilns, high-alumina bricks are mainly used for regenerators, as well as refractory accessories for working pools, material channels and feeders, such as stirring paddles, uniform barrels, punches, etc. High-alumina bricks for glass kilns are a general term for aluminum silicate refractory materials with an Al2O3 content greater than 48%. According to the content of Al2O3, it is divided into three grades: first-grade high-alumina brick, Al2O3>75%; second-grade high-alumina brick, Al2O3 60%~75%; third-grade high-alumina brick, Al2O3 48%~60%.
Compared with clay bricks, most of the functions of high-alumina bricks used in glass kilns are better than clay bricks. The only difference is the thermal stability. According to the different Al2O3 contents, general high-alumina bricks can be divided into three brands: (LZ)-75, (LZ)-65, (LZ)-55, (LZ)-48.
Because the main component of high-alumina bricks is Al2O3, it can resist the corrosion of acidic and alkaline slags, and has a certain resistance to the corrosion of iron oxide. Therefore, it is often used to build the ceiling, bottom and lower wall of the soaking furnace. In the continuous heating furnace, the bottom, wall, burner bricks, ceiling, etc. can all be built with high-alumina bricks. High alumina bricks are also often used as checker bricks to build heat storage chambers.
04 Mullite Bricks
The main component of mullite bricks is Al2O3, with a content of about 75%. Because it is mainly mullite crystals, it is called mullite bricks. Density 2.7-3 2g/cm3, open porosity 1%-12%, maximum use temperature 1500~1700℃. Sintered mullite is mainly used to build heat storage chamber walls.
Electrofused mullite is mainly used to build pool walls, observation holes, wall buttresses, etc.
05 Electrofused Zirconia Corundum Bricks
Electrofused Zirconia Corundum Bricks are also called white iron bricks. Generally, electrofused Zirconia Corundum Bricks are divided into three grades according to the zirconium content: 33%, 36%, and 41%. The zirconium corundum bricks used in the glass industry contain 50%~70% Al2O3 and 20%~40% ZrO2. The density is 3.4~4.0g/cm3, the apparent porosity is 1%~10%, and the maximum operating temperature is about 1700℃. The fused zirconium corundum bricks with a zirconium content of 33% and 36% are used to build the walls of kiln pools, breast walls of flame spaces, small furnace vents, small furnace flat arches, small furnace stacks, tongue arches, etc. The fused zirconium corundum bricks with a zirconium content of 41% are used to build the corners of the pool walls, flow holes, and other places where the refractory materials are most severely eroded by the glass liquid. This material is the most widely used fused cast refractory material in the glass industry.
06 Fused alumina bricks
It mainly refers to fused α, β corundum, and fused β corundum refractory bricks, which are mainly composed of 92%~94% Al2O3 corundum crystal phase, with a density of 2.9~3.05g/cm3, an apparent porosity of 1%~10%, and a maximum operating temperature of about 1700℃.
Fused alumina has excellent resistance to glass permeation and almost no pollution to the glass liquid. It is widely used in the working pool wall, pool bottom, flow channel, working pool wall, pool bottom of the material channel, and other parts of the glass melting furnace that are in contact with the glass liquid and require no refractory contamination.
07 Quartz bricks
The main component of quartz bricks is SiO2, which contains up to 99% or more, with a density of 1.9~2g/cm3, a refractoriness of 1650℃, a working temperature of about 1600℃, and acid erosion resistance. It is used to build the pool wall of acidic boron glass, flame space thermocouple hole bricks, etc.
08 Alkaline refractory materials
Alkaline refractory materials mainly refer to magnesia bricks, alumina-magnesia bricks, magnesia-chrome bricks, and forsterite bricks. Its performance is to resist the erosion of alkaline materials, and its refractoriness is 1900-2000℃. It is widely used in the upper wall of the regenerator of the glass melting furnace, the regenerator arch, the grid body, and some structures of the small furnace.
09 Insulation bricks for glass furnaces
The heat dissipation area of the glass melting furnace is large and the thermal efficiency is low. In order to save energy and reduce consumption, a large amount of insulation materials are needed for comprehensive insulation. In particular, the pool wall, pool bottom, arch, and wall in the regenerator, melting part, working part, etc. must be insulated to reduce heat dissipation. The porosity of the insulation brick is large, the weight is very light, and the density does not exceed 1.3g/cm3. Since the heat transfer performance of air is very poor, the insulation brick with a large porosity has an insulating effect. Its thermal conductivity is 2 to 3 times lower than that of general refractory materials, so the greater the porosity, the better the insulation effect. There are many different types of insulation bricks, including clay insulation bricks, silica insulation bricks, high-alumina insulation bricks, etc.
10 Insulation board for glass kiln
Glass kiln is a key thermal equipment for energy consumption in the glass industry. The use of Helu ceramic fiberboard as the backing insulation board for glass kiln is conducive to maintaining the sealing and insulation effect of the kiln. Use various durable refractory materials, such as capacitor refractory materials, or zirconium, chromium, corundum, spinel and alkaline refractory materials, high-density, high-strength refractory materials, backing insulation ceramic fiberboard, etc. and give reasonable matching, so that the overall service life of the kiln will increase synchronously. The quality of the furnace materials is crucial to the kiln output, glass quality, fuel consumption and furnace age. The use of refractory materials should also be expanded. From a long-term point of view, it is worth spending more on refractory materials.
Wechat Us 
