refractory

As we all know, refractory performance is good or bad with the refractory aluminum content is very close, then we usually use high alumina refractories and clay refractory What is the difference, the following general knowledge to popularize refractory .
    High alumina refractories and clay refractories compared to the outstanding advantages of refractoriness and load softening temperature is high, with the increase of Al2O3 content, slag resistance significantly improved. (1) Refractoriness. High refractory aluminum refractory range, typically 1770 ~ 2000 ℃, mainly affected by the content of Al2O3, with the increase in the content of Al2O3 increased. At the same time, the refractoriness is also affected by the content and type of impurities, which is related to the structure of the product phase. (2) load softening temperature. The deformation temperature of high alumina refractories begins to soften to more than 1400 ℃, and increases with the increase of Al2O3 content. (3) thermal conductivity. High alumina refractory products than clay products with high thermal conductivity. The reason is that the glass with low thermal conductivity in high aluminum products is less, while the amount of mullite and corundum crystals with better thermal conductivity is increased, which improves the thermal conductivity of the products. (4) Thermal shock resistance. High thermal shock resistance of aluminum refractory products between the clay products and silicon products. 850 ℃ water-cooled cycle only 3 to 5 times. This is mainly due to the thermal expansion of corundum mullite than high, and no crystal transition. (5) slag resistance. High aluminum refractory products can resist acidic slag erosion, but also can resist the role of alkaline slag. However, the ability of anti-alkaline slag less than the magnesia, but better than the clay material, and with the mullite and corundum content increases.

The regenerator is a periodic heat exchanger, which belongs to the cyclical unstable temperature field. The heat transfer process is unsteady heat transfer. The working characteristics are similar to the countercurrent heat exchanger, so the regenerator is usually regarded as the counterflow heat exchanger To analyze the entire cycle of heat transfer, thus simplifying the problem.
In the process of heat transfer, the exhaust gas mainly conveys the heat to the surface of the lattice body by convection, and then transfers the heat to the lattice body through the heat conduction; while the heating air mainly convects the heat through the convection and radiation Air, because the air of O2, N2 is a symmetrical two atoms, not radiation or absorption, so the temperature is still high mainly convection heat; heating gas, the radiation can be strengthened. Commutation time has a greater impact on the heat exchange efficiency of the regenerator, the more appropriate time is analyzed as 20 ~ 25min. In addition, the density of bricks, the specific heat capacity, arrangement and gas flow channels also affect the heat exchange process is good or bad. The flow of gas in the regenerator, mainly the uniform distribution of the airflow on the cross section, is of great significance for improving the heat transfer and improving the thermal efficiency. The direction of gas flow should be consistent with the rules of gas vertical movement, that is, flue gas flows from top to bottom, air or gas flows from bottom to top. Compared with the vertical ascending path regenerator, the box regenerator improves the airflow distribution, increases the volume of the lattice, improves the thermal efficiency and reduces the heat dissipation area. The larger the cross-sectional area of ​​regenerator, the more uneven the air flow distribution, especially at the corner, so the upper part of the box regenerator should have enough height.
Its working principle is: when the kiln high temperature exhaust gas from the top down through the small mouth and air, gas channel into the regenerator, the regenerator within the lattice heating, when the lattice temperature gradually increased, a certain savings Of the heat; after the fire, the combustion air and gas from the bottom up through the bottom of the regenerator flue into the regenerator, the regenerator within the lattice body with the accumulated heat to preheat the air and gas, then the lattice Temperature gradually decreased. The working process as shown below shows the regenerative work.

The part of the clarification that is in contact with the glass is in the same environment as the glass in the melting part, except that this part is usually operated at a much lower temperature. The upper structure of these parts of the maximum temperature is generally about 1399 ~ 1454 ℃, while the maximum temperature of most glass may reach 1399 ℃. There is often greater flexibility in choosing refractory materials for these locations because erosion rates are much lower here. However, the more the liquid glass flows toward the forming end of the furnace, the more the quality of the glass is affected by defects in the refractory material. The main reason for this is that the glass in these areas has a high viscosity and at this lower temperature it is difficult for glass to assimilate solid or gas defects originating from the refractory. In addition, the glass does not have much time to ask to complete the process of assimilation of the above defects. ② fluid hole. ③ bridge walls and side walls. ④ feed through the entrance. ⑤ bottom of the pool. 4 Clarification Department of the upper structure ① Overview. Similarly, this part of the temperature is much lower than the melting part. Clarification of the Ministry of the superstructure environment largely depends on the structure of the lattice wall, that is, the end wall and the melting part of the way separated. When using an open cell wall structure, steam condensation may occur due to the conditions in the melting section. The superstructure refractory material reacts on the surface of its refractory material due to its relatively cool area. In general, erosion is caused mainly by alkali vapor. After completely isolating the atmosphere of the fusing part and the fining part, only a very small amount of vapor escaped from the surface of the glass liquid to erode the refractory material in this area. Borosilicate glass furnace does not comply with this law, where the surface of the glass continuously release volatile sodium borate, even in the material so. In general, the best practice for borosilicate glass furnaces is the use of zirconium-based refractory materials or the use of silica-based refractory materials.

Refractory clay is a monolithic refractory material used to prepare a slurry of powdered refractory materials and binders. It is mainly used for masonry brick masonry joints and as a coating material. As a puzzle material or paint use, require the same material and refractory bricks.

Refractory soil, also known as clay refractory soil, a set of furnace with a soil, is a weak acid refractory material, and its good thermal stability, suitable for masonry stove, a variety of boiler lining, and flue, smoke chamber Wait.

Refractory cement is a material used in the manufacture of refractory castables, with a refractory resistance of not less than 1580 ° C. According to the composition of different can be divided into aluminate cement, calcium aluminate, calcium magnesium aluminate and dolomite. When using purely fire-resistant cement, then a lot of cracks will occur after high temperature, it is necessary to pay attention.

Refractory cement and refractory refractory are a kind of fire-resistant cement refractory at 1300 degrees, he has a high strength after condensation, the label can reach 625, mainly mixed with the bauxite aggregate equipment used in refractory high Refractory concrete, fire-resistant refractory soil at 1000 degrees, there is no strength after the coagulation, only play a certain bonding effect, refractory soil is generally used for brick masonry or paste wall furnace.

If the fire-resistant cement and refractory soil are used in combination, then the value of refractory cement will be greatly discounted, equivalent to the fire-resistant cement and loess mixed together as one reuse, refractory cement coagulation strength and labeling will be much lower.

Refractory selection principles Refractory selection before you need to first understand the following factors: ① the life of the pool furnace; ② glass quality requirements; ③ production capacity, that is, the melting rate and melting temperature selection; ④ insulation, in order to save fuel in the Which parts to take insulation; ⑤ economy, that is, how much investment. In the selection of refractory materials to hijack the use of requirements to ensure the economy of the pool furnace, easy to manufacture. (1) Ensure that all kinds of refractory materials used for building glass pool furnaces should meet the following basic requirements: ①High softening and melting temperature, generally not less than 1580 ℃. ② sufficient mechanical strength, can resist the impact, friction, high temperature high-speed flame, dust erosion and other mechanical effects. ③ high temperature structural strength, operating temperature can withstand long-term mechanical load. ④ melting compound ingredients, molten glass and gaseous substances erosion resistance strong. ⑤ the pollution of the glass should be small. ⑥ hot and cold-resistant thermal performance (thermal shock) is good. ⑦ high temperature volume stability, residual contraction or expansion of small. ⑧ heat capacity, thermal expansion, thermal conductivity and other thermal properties to meet the requirements. ⑨ shape regular, accurate size. ⑩ other requirements according to the conditions of use (such as the electrical properties of the electrode brick to meet the requirements). (2) to ensure the economy of the pool furnace Refractories should be taken from the actual departure, the full study of the entire furnace furnace refractory life balance of various parts, with less investment to achieve greater economic results. Fully guarantee the economy of the glass pool furnace and the balance of the life of the pool furnace. (3) easy to manufacture and choose Refractory, should be taken into account the use and manufacture of both. Refractory brick, the standardization of the size is conducive to the development of refractories production, easy to achieve the finalization of the glass pool furnace is conducive to construction and maintenance. S & P brick usually cost 30% to 50% less than shaped brick. Indigenous glass furnace should be given priority to the use of standardized refractory brick. 5.3 Furnace operation and maintenance Reasonable furnace operation system is to extend the useful life of the furnace and access to quality products, an important guarantee that the operation of the furnace must be strictly in accordance with the provisions of process documents

Refractory materials are the main building blocks of glass melting furnaces and have a decisive influence on the quality of glass, energy consumption and even the cost of the product. The development of glass melting technology depends largely on the progress of refractories manufacturing technology and quality improvement. Glass Furnace Furnace Structure For large float lines, the glass kiln is usually constructed of L-shaped hanging wall (usually using silica bricks), melting section (fused glass in direct contact with glass, upper used (Usually using silica bricks), the cooling section including the ototoxic tank (where the corundum material is used in direct contact with the liquid glass, and silica brick or corundum is used where it is not in contact with the liquid glass), annealing Kiln, regenerator (made of clay, high aluminum, direct combination of magnesia-chrome brick) and other parts. Glass furnace main parts of the conditions of use and refractory choice
Glass melting furnace and cooling Department of the top (including the arch angle), the site is often at 1600 ℃ operating temperature, the use of refractory material in this area is subject to high temperature, load but also by the alkali steam and compound Therefore, the material used for the top must have high refractoriness, high load softening temperature and good creep resistance, and the thermal conductivity is small, the erosion of high temperature does not pollute the glass liquid, the bulk density is small, High temperature strength and other characteristics. The high-quality high-purity silica brick with just the above characteristics: 1, the load temperature close to the refractory; 2, high temperature stability, high strength; 3, due to the main component of SiO2, content> 96%, the same as the main components of glass , So erosion under high temperature basically does not pollute the glass liquid; 4, the price is cheap. Therefore, at present, in the top of large-scale glass, pure high-quality high-purity silica bricks become the glass of choice for manufacturers. The chemical attack caused by high temperature chemical reaction between fly ash, alkali vapor and refractory materials, as well as the change of the crystal form and the change of the structure due to temperature and phase migration are the main reasons for the damage of the top tile. The results show that the high-quality glass kiln silica brick is used in the top of 碹 roof, and the alteration process at high temperature is basically phase transformation and impurity migration. The chemical attack and melting effect are extremely slight. As a result of phase change and self-purification, the working belt gradually changes its performance and its high temperature performance is improved.

Refractory raw materials processing is to enter the factory of various shapes and sizes of refractory raw materials (including raw ore and clinker) into the required size, and remove impurities mixed with refractory raw materials for the preparation of brick use. Refractory raw material processing include: selection of refractory raw materials, crushing, grinding, fine grinding and screening.
The selection of raw materials into the plant
The selection of refractory raw materials into the plant there are two main purposes: (1) selected mixed in the raw materials in the debris, under burning material, not burning fuel and tumor blocks, etc .; (2) According to the appearance of refractory raw materials Features are stacked for ease of management and use.
Broken smashing purposes
The mechanical method (or other methods) exerting external force on the large refractory raw materials so as to fragment them into small pieces or fine powders is called raw material crushing and pulverizing.
Usually two or three broken crushed. That broken – broken pieces of material from 250-300mm broken 40-50mm;
Crush – Material block size from 40-50mm crushed to 4-5mm;
Fine grinding – finely ground material size from 4-5mm to less than 0.088mm.
The purpose of crushing is to prepare massive refractory raw materials into pellets and fine powders with a certain granular composition so that powders of different compositions are prepared and mixed uniformly; the specific surface area of ​​the raw materials is increased and the physicochemical reaction speed is increased.
Impact broken broken factors

Insulation brick seven major features: Insulation, insulation: effectively reduce energy consumption. Fire: A national standard or not. Clean, environmentally friendly: will not cause secondary air pollution. Light weight: only about 1.4 kg

1. Porosity The apparent porosity reflects the density of the refractory material, ie the percentage of apparent pore volume in the brick to the total volume of the brick.
Bulk density is the mass of the total volume of refractory unit volume, including pores.
3. True density Refractory unit volume does not include the stomatal volume of the quality.
Thermal properties

In the glass industry, the quality of refractory materials is of great significance for improving the quality of glass products, saving fuel, prolonging the life of melting furnace and reducing the production cost of glass. Refractory materials are the material basis of glass furnaces and have a great impact on the overall kiln efficiency. They must be properly selected. Different parts of the pool kiln performance requirements of different refractory materials are also different. The basic requirements for refractories for glass melting furnaces are generally as follows. Sufficient performance is required.  such as high temperature performance, chemical stability, hot and cold emergency stability, volume stability and mechanical strength. Pollution or minimal pollution Maximize service life No contact between refractory materials of different materials built up at high temperatures Reactivity and size Exactly as small as possible Heat and radiation losses  Vulnerable parts made of high quality materials  Other parts used General materials. Achieve “a reasonable package  kiln age synchronization
Melting Department in contact with the glass of the site
Most glass-contact refractory materials are damaged by liquid-phase erosion dominated by diffusion. Soda lime glass has a liquid temperature of up to about 1500 ° C. The glass temperature of other glasses than soda lime glass may be higher or lower depending on the required viscosity characteristics of the glass and the composition of the glass. The most important property of refractory material for all glass-contacting parts is resistance to corrosion. The two properties of refractory interface stability and the tendency to produce stones are almost equally important. Interfacial stability means that the refractory material is partially eroded  However, the surface of the refractory material is still intact and will not fall off and the glass will be defective.

Alumina content of more than 48% of a neutral refractory. By the bauxite or other high alumina content of the material by molding and calcined. High thermal stability, refractoriness above 1770 ℃. Better slag resistance. For masonry EAF, glass furnace, cement rotary kiln and other fabrics.
High load soft, low creep high alumina brick is a high-grade refractory made of premium alumina, fused corundum, fused mullite as the main material. The product has a high temperature creep small, strong corrosion resistance, thermal shock resistance and good long-term, suitable for large and medium-sized stove, it is China’s new hot-blast stove required high-quality, high-grade imported refractory domestic pioneers Next The road to success, has been included in the national “Spark Program” project.
a, refractoriness
High alumina brick refractory than clay brick and half-brick refractory high, reaching 1750 ~ 1790 ℃, attributed to high-grade refractory materials.
b, load softening temperature
Because the high alumina content of Al2O3, less impurities, the formation of friable vitreous less, so the load softening temperature higher than the clay brick, but because of the formation of mullite mesh structure, so the load softening temperature is still no high silica brick.
c, slag resistance
Alumina Al2O3 brick more, close to the neutral refractory material, can resist the corrosion of acid and alkaline slag, because of the SiO2, so the ability to resist alkaline residue than acid residue ability weaker.
The use of high alumina bricks
Mainly used for masonry blast furnace, hot stove, electric stove roof, blast furnace, reflector furnace, rotary kiln lining. In addition, high alumina bricks are also widely used as hearth heat regenerative lattice bricks, plugs used in casting systems, nozzle bricks and so on. However, the price of high-alumina brick clay brick is high, so the clay brick to meet the requirements of the local do not have to use high-alumina brick.