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The current trend of glass furnace refractory applications

There are three main drivers of changes and developments in refractory materials. The first is the glass manufacturer's need to improve the quality of the glass, at least for the most part. The second is the economic requirements of glass furnaces to make kilns run longer, and the third is the impact and impact of pure oxygen combustion systems. These three requirements often determine the use of improved refractory materials when repairing a kiln. These impetuses have also prompted glass manufacturers to choose improved refractory products for furnace maintenance and to adopt new technologies for extensive overhaul in their operating cycles.

Melt-cast alumina bricks have established their use in the top of the melting tank, primarily in pure oxygen fired furnaces melting high-quality glass. Before the advent of pure oxygen combustion technology, only β ˉ alumina bricks were used to melt the superstructure of the cell and alumina-free bricks without melt-casting were applied to the top of the melting cell. Today, both molten cast products of β-alumina and α-β-alumina are used in the production of some or all of the roofs of pure oxygen combustion furnaces for color television sets (screens and cones), float glass and borosilicate glass on. Melt-cast AZS bricks can typically be used at 1600 ° C or 1650 ° C (depending on the glazing), while furnace tops made of fused alumina brick can be successfully run at 1700 ° C. This creates better conditions and greater flexibility for glass manufacturers in the production of refractory glass.

For many years, melt-cast AZS furnace roofs have successfully undergone the test of cooling and reheating to enable them to use multiple operating cycles. There is now a bit of experience in successfully implementing the top cooling and reheating of fused-alumina roofs, which represent an economically viable life when they use two or more cycles of operation. The results of the observation of the fused alumina roof in service (thermal observation and shutdown observation) show that these materials are both chemically and mechanically stable. This is the first observational study of such masonry because there was neither a reference to fused alumina at the time nor the empirical basis for its application to the roof.


Reflections on the Development of Glass Industry Refractories

In recent ten years, China's glass industry has made considerable progress with the refractory materials, embodied in the large-scale float glass furnace kiln age, from 3 to 4 years to 5 to 8 years, and all materials to achieve localization, greatly Narrow the gap with the advanced level of foreign countries for the glass industry with the future development of refractory materials, and laid a solid foundation.

     In recent years, China has built more than 30 cast refractory materials enterprises, these enterprises in recent years despite the majority of varying degrees of progress, but most of the smaller scale of production, technology is weak, backward technology and equipment, product quality is difficult to guarantee. The company must have its own controllable production scale and supporting system of fused cast refractory, basic refractory, silica brick, zirconium, zirconium corundum, sillimanite, mullite refractory and new amorphous refractory material. Can provide the entire kiln refractory quality supporting materials to meet the entire glass industry, including glass fiber industry, the needs of refractory materials.

Glass furnace design, refractory production, melting furnace operation, maintenance, use and production of refractory materials and the use of scientific research between the four closely integrated, is to extend the melting furnace kiln, as soon as possible to reach the international advanced level of the important conditions one.

To extend the melting furnace kiln age must have two conditions: First, the integration of industry and trade branch of Refractories Company, to provide the furnace required for a variety of high quality refractory supporting materials; the second is to design, production, use and research Tight combination, to play their own advantages, so that the configuration of the whole furnace refractory more reasonable, superb design, meticulous operation, maintenance and management of high-quality refractory materials and supporting the supply must be closely integrated.


Glass furnace refractory applications trends

For many years, melt-cast AZS furnace roofs have successfully undergone the test of cooling and reheating to enable them to use multiple operating cycles. There is now a bit of experience in successfully implementing the top cooling and reheating of fused-alumina roofs, which represent an economically viable life when they use two or more cycles of operation. The results of the observation of the fused alumina roof in service (thermal observation and shutdown observation) show that these materials are both chemically and mechanically stable. This is the first observational study of such masonry because there was neither a reference to fused alumina at the time nor the empirical basis for its application to the roof.

High-chromium refractory products in the past mainly used to enhance the glass furnace, and a small amount used in insulation glass pool furnace. High chrome bricks are increasingly being used in some soda lime glass furnaces. Its main use has not only been limited to all or part of the flow hole, but also to the end wall and, to a limited extent, the corner brick for the feed opening The high-chilled brick masonry cavity provides the potential for increased kiln life Because this material is at least twice as corrosive to most glasses as molten AZS bricks.

It has been several years since low-glass phase fused AZS refractories have been successfully used in molten pool superstructures on a limited basis. Pure oxygen combustion technology has led to its wider use in the superstructure of molten pools for two reasons: first, the low glass phase content leads to a low bleed out of the glass phase, which is higher than that of the traditional molten AZS brick Structure is more "dry." Second, the low glass phase content makes it more creep-resistant so that the normal operating temperature can be raised from 1600 ° C to 1650 ° C. This is more useful for the superstructure of the feed zone of a pure oxygen fired furnace where the molten AZS brick not only has the resistance to dust particles from the combustion air flow but also can withstand higher temperatures 1650 ℃. Molten pool wall tiles have recently been developed to improve the top (liquid line) anti-erosion properties of new varieties and has been in the field test. This pool wall brick utilizes a unique approach that controls the crystal structure of the liquid line section so that the brick has a much stronger erosion resistance at the liquid line than the standard fused AZS brick.

High zirconium fused wares (HZFC or fused zirconia) have been widely accepted as refractories in contact with glass for use in specific locations in certain high quality glass furnaces. The reasons for using the refractory of this kind of component vary from one glass type to another. Color TV picture tube screen glass is a serious erosion of HZFC but it is also used as a base and pool wall tile at the end of a melt pool flow hole because it significantly reduces glass defects such as knuckles, bubbles and stones . The corrosion resistance of fused zirconia refractories is not superior to that of molten AZS, but usually it suffices to maintain an entire kiln cycle. In this way, the use of HZFC in color picture tube screen glass cell furnaces can greatly improve the quality of the glass without reducing the life of the kiln.


The adhesion of refractories materials

Thermal kilns and equipment require many specific shapes of refractory brick masonry. This requires a material that has some adhesion at both ambient and elevated temperatures. Usually we use refractory mud to achieve our goals. Silica, clay, high aluminum, magnesium refractory mud, at room temperature, through the intermolecular force, to achieve the bonding between refractory products. During high temperature use, ceramic bonding is generally achieved due to the sintering effect. In order to achieve ceramic bonding at lower temperatures, it is often necessary to add some sintering promoter in the slurry to sinter it in advance.

Recently, more and more composite adhesives are used. These include dextrin, silica sol, water glass, brine, refractory cement, leeches, resins, etc. at ambient room temperature, as well as chemical or other forms of bonding at moderate or elevated temperatures , To improve the strength of the material. In addition to most of the above-mentioned refractory materials have this feature, there are phosphoric acid, a variety of phosphate, polyphosphate, metaphosphate, sulfate, all kinds of ultrafine powder

In addition, organic binders are also one of the most popular refractory binders currently available and include tar, resins, modified bitumens, and the like. These binders have good bond strength at room temperature and form a carbon bond network after high temperature.

Because of its complementarity to various properties, organic binders are rapidly expanding and deepening their research because of their carbon residue is conducive to the high temperature performance of refractory materials.


What requirements should refractories meet?

Refractory materials used in a variety of high temperature equipment, which is subject to physical and chemical erosion and mechanical damage under high temperature conditions, the performance of refractory materials should meet the following requirements:

1, high refractoriness Modern metallurgy furnace and other industrial furnace heating temperature are generally between 1000 ~ 1800 ℃. Refractory materials should have a low melting temperature at high temperatures.

2, high temperature structural strength should be large. Refractory should not only have a higher melting temperature, but also should have under the load of the furnace masonry or other mechanical vibration, without softening deformation and collapse.

3, thermal stability is better. Metallurgical furnaces and other industrial kilns in the operation process due to sudden changes in temperature refractory parts of the uneven temperature, there will be stress inside the masonry and fission and spalling of the material. Therefore, refractory materials should have the ability to resist such damage.

4, strong slag resistance. Refractory materials in the use of the process, often by high temperature slag, metal and furnace dust chemical attack. Therefore, refractory materials must have the ability to resist erosion.

5, high temperature and volume stability. Refractory materials in the long-term high temperature use, the brick body will produce the volume contraction or expansion, resulting in the refractory brick damage. Therefore, refractory materials are required to be stable in volume at high temperature.

6, structured dimensions, tolerances should be small. Although the refractory brick masonry brick filled with refractory mud, but the density and intensity are worse than the refractory material in the drying process and easy to fall off, so the brick is the weak link masonry, easy to leak and erosion Therefore, the smaller the seam size, the smaller the better. Only the accurate dimensions can meet this requirement. Therefore, the refractory material can not have the defects of big distortion, lack of edge, notch, cave and crack, etc. Claim.


Focus on the refractory industry and optimize the structure

Since 2000, China's refractory industry has entered the fastest-growing stage and is now the world's largest producer and exporter of refractory materials. European Refractories Manufacturers Association survey of the global refractory production in 2011 showed that the global refractory output in 2011 was 42,750,000 tons, of which, China's refractory output was 29,500,000 tons, accounting for 69% of the global output.

With the relative trend of the company's shares Pu-resistant shares, Beijing Lill major innovation ability and technology and equipment levels have improved significantly, China's refractory industry in the international market, the advantages and status of refractory material has also been greatly improved. At present, the varieties and aggregates of refractory products in our country not only meet the needs of domestic high-temperature industrial production and development, but also increase their export volume year by year. The market covers more than 150 countries and regions in Asia, Europe and the Americas, and the export volume has been ranking the world for many years the first.

At present, China's refractory products industry will focus on the development of product structure optimization, focus on extending the industrial chain and enhance the overall competitiveness of industries; vigorously develop the deep processing of products, improve product added value and technical content, improve product quality; focus on the development of a safe, Environmental protection, energy saving, noise reduction, leakage prevention and other functions of new building materials and products to meet the needs of green building development.

Refractory products industry will speed up the development of inorganic non-metallic materials to support the development of strategic industries, promote joint reorganization, optimize the industrial layout, strengthen energy consumption, strict environmental management, development of high-end products, encourage technological innovation, eliminate backward production capacity and strengthen safety Production and other eight tasks, to refractory products listed companies and listed companies has brought new opportunities.


Refractory production process introduction, glass technology

According to the degree of compactness and shape of different products, there are sintering, casting and melt casting method.

Sintering method is to pre-burn the department of raw materials into clinker, crushing and screening, and then press a certain ratio and raw materials mixed by forming, drying and firing.

Casting method is the raw materials through mixing ingredients and fine grinding and other processes, melting at high temperatures, direct casting, cooling and crystallization, annealing products.

Their compact body, high mechanical strength, high temperature structural strength, slag resistance is good, the scope of use continues to expand. Melt blowing method is to melt the ingredients, the high pressure air or superheated steam injection, so that the dispersion into fibers or hollow ball method.

Products are mainly used as light refractory, heat insulation materials, but also made of powder or granular amorphous refractories, temporary use of tar, asphalt, cement, phosphate, sulfate or chloride binder bonding, without Forming and sintering directly.