Three-section type high borosilicate glass melting furnace

Abstract

The utility model discloses a three-section type high borosilicate glass melting furnace which comprises an all-electric melting section, an all-oxygen high-temperature clarification section and a platinum material channel cooling section, the all-oxygen high-temperature clarification section is located on one side of the all-electric melting section, and the platinum material channel cooling section is located on one side of the all-oxygen high-temperature clarification section; the all-electric melting section comprises an all-electric melting furnace bottom insertion electrode, an all-electric melting furnace tank bottom, an all-electric melting furnace electrode, an all-electric melting furnace tank wall and an all-electric melting furnace arch top. According to the three-section type high borosilicate glass melting furnace disclosed by the utility model, the melting part of the all-electric borosilicate glass cold top electric melting furnace is used, materials are fed from the top of the melting furnace, raw materials are heated and melted from top to bottom, and after the thickness of a raw material layer is 800-150mm, not only is high-temperature heat in the melting furnace not lost, but also volatilization of boron is effectively controlled; the volatilization amount of boron volatilized in the all-electric melting furnace is less than 1%, and the heat efficiency reaches more than 85% when an electrode is used for heating inside the glass liquid, so that the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The utility model relates to the field of glass melting, in particular to a three-stage high borosilicate glass melting furnace. Background Art

[0002] A glass melting furnace is a supporting device for glass melting operations. The glass melting process is divided into five stages:

[0003] Silicate formation, glass formation, fining, homogenization, and cooling.

[0004] 1. Formation of silicates

[0005] The batch material undergoes a series of physical and chemical changes during the heating process, and most of the gaseous products escape from the batch material and become an opaque sinter composed of silicate and silicon dioxide.

[0006] 2. Formation of glass

[0007] The sintered material is continuously heated and begins to melt. The silicate and the remaining silicon dioxide fuse together, and eventually the sintered material becomes a transparent body with no unreacted batch material particles. However, there are a large number of bubbles in the glass liquid, and the glass itself is uneven in chemical composition and properties, with many stripes.

[0008] 3. Glass clarification

[0009] As the glass melt continues to heat, its viscosity decreases and gaseous impurities are released from it, which is a process of removing visible bubbles.

[0010] 4. Homogenization of glass

[0011] When glass melt is exposed to high temperatures for a long time, its chemical composition gradually becomes more uniform. This is because diffusion reduces streaks and lumps in the glass to a certain extent, resulting in a uniform structure. The homogeneity of glass melt can be determined by measuring the consistency of density or refractive index in different areas of the glass.

[0012] 5. Cooling of glass

[0013] After clarification and homogenization, the temperature of the molten glass is lowered so that the molten glass has the viscosity necessary for forming. With the continuous development of science and technology, people have higher and higher requirements for the manufacturing process of glass melting furnaces.

[0014] Borosilicate specialty glass, also known as high borosilicate glass, is a type of borosilicate glass used in technical applications. Its basic components are SiO2, B2O3, and Na2O. The composition ranges from ω(SiO2)=70%-80%, ω(B2O3)=6%-15%, ω(Na2O)=4%-10%, ω(Al2O3)=0-5%, ω(BaO)=0-2%, and ω(CaO)=0-2%. Borosilicate specialty glass exhibits many excellent properties, including excellent thermal, chemical, mechanical, process, and optical stability. Compared to ordinary soda-lime-silica glass, borosilicate specialty glass offers low expansion, high temperature resistance, high strength, high hardness, high light transmittance, and high chemical stability. It is widely used in home appliances, fire protection, bulletproofing, solar energy, chemicals, pharmaceutical packaging, electric light sources, and decorative arts.

[0015] There are a series of difficulties in the production of borosilicate special glass:

[0016] 1. High Viscosity: Borosilicate specialty glass contains over 80% SiO2 and over 10% B2O3. The high SiO2 content and low Na2O content result in a high melting point for borosilicate glass, with the hotspot temperature reaching over 1680°C. Furthermore, because the silicon-oxygen tetrahedra in the glass structure mostly exist as large tetrahedrons, the tetrahedra are often connected by silicon-oxygen bonds. Furthermore, the 12% to 13% B2O3 content can reconnect a large portion of the network previously severed by Na2O with a B-O triangular structure. This results in a very high viscosity for high borosilicate glass, making it difficult to melt and clarify the glass.

[0017] 2. Prone to stratification and crystallization: During the melting process, borosilicate glass can also experience stratification. Because the lower layer of conventional flame-heated tank furnaces lacks a heat source, the temperature decreases as the tank depth increases. This reduces the fluidity of the lower layer, causing heavier components like Al2O3 to sink, forming a metamorphic layer high in Al2O3. When temperature and flow fluctuate, these components are easily entrained in the glass flow, resulting in defects such as streaks. Furthermore, due to the high SiO2 content, crystallization is more likely to occur in lower temperature areas, leading to the formation of stones.

[0018] 3. Boron Volatility: The volatilization of B2O3 is another characteristic of the borosilicate glass melting process. This volatilization forms a layer of silicon-rich glass on the surface of the molten glass, which not only affects the chemical composition of the glass, but also increases with increasing temperature. This is undoubtedly detrimental to the high-temperature melting required for borosilicate glass. If this silicon-rich glass is carried into the forming process under changing operating conditions, defects such as streaks and stones may form in the final product.

[0019] Due to these characteristics, melting high-borosilicate glass is difficult. Therefore, to date, most domestic manufacturers are still limited to melting in small flame tank kilns and crucible furnaces, and then supplying small-scale production for manual blow molding. This consumes a lot of energy, has a low yield rate, and is labor-intensive. To meet market demand and improve my country's melting technology, the domestic glass industry has been trying to solve this problem. To melt high-quality high-borosilicate glass, an important way is to increase the temperature of the glass liquid. However, considering the tolerance of the refractory materials in the flame space, it is difficult to heat the glass liquid to above 1650°C by flame heating alone. Foreign countries have generally adopted the full oxygen combustion flame melting method with electric fluxing for melting this type of glass, but this method has high energy consumption and serious boron volatilization, which keeps the glass manufacturing cost high.

[0020] Most of the electric melting furnaces used to melt borosilicate glass in my country are cold-top electric melting furnaces, which have significant advantages over flame furnaces, such as energy saving and cost reduction. However, the glass clarification effect is poor, there are many stone-like defects, the production line yield is low, and the overall quality is inferior to foreign products.

[0021] Defects and shortcomings of existing borosilicate glass melting furnaces

[0022] 1. Foreign countries use the full oxygen electric-assisted melting tank furnace process, and the daily melting capacity can reach 50 tons / day, but the energy consumption is as high as 3000Kcal / kg glass liquid, and the boron volatilization rate reaches 15-20%, resulting in a large amount of raw material waste and environmental pollution. At the same time, due to the volatilization of boron, a silicon-rich layer is formed on the surface of the tank furnace glass, and alumina deposition and crystallization occurs in the lower layer of the tank furnace. Only about 70% of the high-quality glass liquid can be used, and the daily glass output is only about 30 tons. This is one of the reasons why the price of imported borosilicate glass reaches more than 60,000 yuan / ton.

[0023] 2. Domestic production of borosilicate flat glass uses all-electric melting furnaces, which consist of a melting pool, a flow hole and a horizontal channel. Due to problems such as the electrode layout characteristics, the maximum daily melting capacity can only be 30 tons / day, with an energy consumption of about 1000Kcal / kg of glass liquid and a boron volatilization rate of about 2-3%. Due to the high melting point and poor thermal conductivity of borosilicate glass, the high-temperature melting zone of the electrode is concentrated within 500mm around the electrode, which causes uneven melting temperature in the entire melting pool and a low-temperature melting zone in the middle of the melting pool, which cannot satisfy the requirement that all glass liquid undergoes a high-temperature clarification stage. This results in unsatisfactory melting, clarification and homogenization. At the same time, due to laminar flow and slow movement speed of the glass liquid at the bottom of the melting pool and in the horizontal channel, alumina deposition and crystallization are easily generated, which ultimately leads to product quality being inferior to imported products in terms of bubble quantity, glass tendon degree, and stone defects. The yield rate is also lower than the international level, making it difficult for the product to enter the high-end market.

[0024] In summary, the existing borosilicate glass melting furnace has the following disadvantages:

[0025] All-oxygen electric boost melting furnace: high energy consumption and serious boron volatilization.

[0026] All-electric melting furnace: There is a low-temperature zone in the middle of the glass liquid, which cannot make all the glass liquid clear at high temperature. There are many bubbles and heavy glass ribs. For this reason, we propose a three-stage high borosilicate glass melting furnace. Utility Model Content

[0027] Technical problems solved: In response to the shortcomings of the existing technology, the utility model provides a three-stage high borosilicate glass melting furnace, which uses an all-electric borosilicate glass cold-top electric melting furnace melting part. Raw materials are added from the top of the melting furnace, and the raw materials are heated and melted from top to bottom. When the thickness of the raw material layer is 800-150mm, it not only ensures that the high-temperature heat in the melting furnace is not lost, but also effectively controls the volatilization of boron, so that the volatilization amount of boron in the all-electric melting furnace is less than 1%. Electrodes are used to heat the glass liquid inside, and the thermal efficiency reaches more than 85%, achieving the purpose of energy saving and emission reduction, which can effectively solve the problems in the background technology.

[0028] Technical solution: To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a three-stage high-borosilicate glass melting furnace, including an all-electric melting section, an all-oxygen high-temperature clarification section and a platinum material channel cooling section, wherein the all-oxygen high-temperature clarification section is located on one side of the all-electric melting section, and the platinum material channel cooling section is located on one side of the all-oxygen high-temperature clarification section;

[0029] The all-electric melting section includes an all-electric melting furnace bottom plug electrode, an all-electric melting furnace pool bottom, an all-electric melting furnace electrode, an all-electric melting furnace pool wall, an all-electric melting furnace crown, an all-electric melting furnace liquid surface, an all-electric melting furnace liquid flow hole and an all-electric melting furnace discharge port;

[0030] The full-oxygen high-temperature clarification section includes a clarification section ascender, a clarification section smoke exhaust port, a clarification section full-oxygen spray gun, a clarification section crown, a clarification section liquid surface, a clarification section breast wall, a clarification section bottom plug-in electrode, a clarification section discharge port, a clarification section bridge dam, a clarification section pool wall, a clarification section top discharge port, a clarification section full-oxygen spray gun installation port, and a clarification section ear pool flat crown;

[0031] The platinum channel cooling section includes a cooling part brick channel, a first cooling part discharge port, a second cooling part discharge port, a cooling part platinum stirring mechanism, a cooling part platinum channel and a cooling part brick structure.

[0032] Preferably, the all-electric furnace bottom plug-in electrode is positioned on the all-electric furnace pool bottom, the all-electric furnace electrode is positioned on the all-electric furnace pool wall, the all-electric furnace pool wall is positioned at the top of the all-electric furnace pool bottom, the all-electric furnace crown is positioned at the top of the all-electric furnace pool wall, and the all-electric furnace liquid flow hole is located at the outlet of the all-electric melting section.

[0033] Preferably, the smoke exhaust port of the clarification section and the all-oxygen spray gun of the clarification section are both located on the breast wall of the clarification section, the top of the clarification section is located at the top, the bridge-type retaining dam of the clarification section is located in the middle section of the bottom, the ascending way of the clarification section is located in the feeding section of the all-oxygen high-temperature clarification section, the all-oxygen spray gun of the clarification section is installed on the all-oxygen spray gun installation port of the clarification section, and the top discharge port of the clarification section is opened on the flat yoke of the clarification section ear pool.

[0034] Preferably, the first cooling section discharge port is located at the bottom of the cooling section brick channel, the cooling section platinum stirring mechanism is located inside the cooling section brick structure, and the second cooling section discharge port is located at the bottom of the cooling section platinum stirring mechanism, and the cooling section platinum channel is located in the cooling section brick structure.

[0035] Preferably, the all-electric melting furnace inside the all-electric melting section adopts a cold top vertical melting structure, and the flow hole structure inside the all-electric melting section is extended to the middle of the all-electric melting section and reaches the center line position, so that the glass liquid on the flow hole side and away from the flow hole side can enter the flow hole as evenly as possible.

[0036] Beneficial Effects: Compared with existing technologies, the present invention provides a three-stage high borosilicate glass melting furnace with the following beneficial effects: This three-stage high borosilicate glass melting furnace utilizes a fully electric borosilicate glass cold-top melting furnace. Material is fed from the top of the furnace, and the raw materials are heated and melted from top to bottom. When the raw material layer is 800-150mm thick, this ensures that the high-temperature heat in the furnace is not dissipated and effectively controls boron volatilization, reducing the boron volatilization rate in the fully electric melting furnace to less than 1%. Electrodes are used to heat the glass liquid, achieving a thermal efficiency of over 85%, achieving energy conservation and emission reduction.

[0037] Compared with the traditional all-electric melting furnace glass production line, the all-oxygen high-temperature clarification section is used. An all-oxygen high-temperature clarification section is added between the electric melting furnace and the horizontal material channel. Bottom-inserted electrodes are installed in the glass liquid in the clarification section, and multiple groups of all-oxygen burners are installed in the upper space of the glass liquid. A bridge-type dam and a bottom discharge hole are arranged on the structure to further heat the glass liquid coming from the all-electric melting furnace, reduce the viscosity, and fully eliminate the bubbles in the glass liquid to achieve the ideal clarification effect. In particular, the application of the bridge-type dam can completely reduce the temperature difference between the inside and outside of the glass liquid, so that the glass liquid can be clarified while being well homogenized in temperature and composition.

[0038] The use of a cooling section with a platinum channel ensures that the glass liquid can be cooled synchronously inside and outside during the cooling process, avoiding the temperature difference between the middle and the periphery, while also reducing the contamination of the glass liquid by refractory materials.

[0039] In the all-oxygen high-temperature clarification section, a pair of symmetrically positioned continuous discharge ports are installed at the top to discharge the silicon-rich surface glass liquid caused by boron volatilization, thereby reducing the formation of siliceous stones and carbuncle. In the all-oxygen high-temperature clarification section, a pair of symmetrical continuous flue gas exhaust ports are installed at the front end of the breast wall to discharge the exhaust gas generated by the all-oxygen combustion.

[0040] Discharge ports are set at the end of the liquid flow tunnel of the all-electric melting furnace, the front end of the bridge-type dam in the clarification section, the climbing part of the brick material channel in the cooling section, and the bottom of the platinum material channel. These ports can continuously or intermittently discharge aluminum-rich deposits produced by stratification, thereby avoiding optical deformation and quality problems of the glass plate surface caused by uneven composition.

[0041] The use of platinum stirring and platinum material channels with heating functions can effectively achieve controllable cooling, that is, to achieve uniform and homogeneous cooling inside and outside the glass liquid during the cooling process, ensuring that the glass liquid entering the tin bath for forming meets the homogenization requirements in terms of composition and temperature. The entire glass melting furnace has a simple structure and is easy to operate, and the effect of use is better than that of traditional methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The utility model is a schematic longitudinal section of a three-stage high borosilicate glass melting furnace.

[0043] Figure 2 This is a schematic plan view of a three-stage high borosilicate glass melting furnace of the utility model.

[0044] Figure 3 This is a schematic plan view of the upper space of the full oxygen high-temperature clarification section of a three-stage high borosilicate glass melting furnace of the present invention.

[0045] Figure: 1. All-electric melting section; 2. All-oxygen high-temperature clarification section; 3. Platinum material channel cooling section; 4. All-electric melting furnace bottom electrode; 5. All-electric melting furnace pool bottom; 6. All-electric melting furnace electrode; 7. All-electric melting furnace pool wall; 8. All-electric melting furnace crown; 9. All-electric melting furnace liquid level; 10. All-electric melting furnace liquid flow hole; 11. Clarification section ascender; 12. Clarification section smoke exhaust port; 13. Clarification section all-oxygen lance; 14. Clarification section crown; 15. Clarification section liquid level; 16. Clarification section breast wall; 17. Brick channel of cooling section; 18. Platinum stirring mechanism of cooling section; 19. Platinum channel of cooling section; 20. Brick structure of cooling section; 21. Discharge port of second cooling section; 22. Discharge port of first cooling section; 23. Bridge dam of clarification section; 24. Discharge port of clarification section; 25. Bottom electrode of clarification section; 26. Discharge port of all-electric melting furnace; 27. Pool wall of clarification section; 28. Discharge port at top of clarification section; 29. ​​Installation port of all-oxygen lance of clarification section; 30. Flat sill of ear pool of clarification section. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0047] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0049] like Figure 1-3 As shown, a three-stage high borosilicate glass melting furnace includes an all-electric melting section 1, an all-oxygen high-temperature clarification section 2, and a platinum forehearth cooling section 3. The all-oxygen high-temperature clarification section 2 is located on one side of the all-electric melting section 1, and the platinum forehearth cooling section 3 is located on one side of the all-oxygen high-temperature clarification section 2.

[0050] The all-electric melting section 1 includes an all-electric melting furnace bottom plug electrode 4, an all-electric melting furnace pool bottom 5, an all-electric melting furnace electrode 6, an all-electric melting furnace pool wall 7, an all-electric melting furnace crown 8, an all-electric melting furnace liquid surface 9, an all-electric melting furnace liquid flow hole 10 and an all-electric melting furnace discharge port 26;

[0051] The all-oxygen high-temperature clarification section 2 includes a clarification section ascender 11, a clarification section smoke exhaust port 12, a clarification section all-oxygen spray gun 13, a clarification section crown 14, a clarification section liquid level 15, a clarification section breast wall 16, a clarification section bottom plug-in electrode 25, a clarification section discharge port 24, a clarification section bridge dam 23, a clarification section pool wall 27, a clarification section top discharge port 28, a clarification section all-oxygen spray gun installation port 29, and a clarification section ear pool flat crown 30.

[0052] The platinum channel cooling section 3 includes a cooling part brick channel 17 , a first cooling part discharge port 22 , a second cooling part discharge port 21 , a cooling part platinum stirring mechanism 18 , a cooling part platinum channel 19 and a cooling part brick structure 20 .

[0053] Furthermore, the all-electric melting furnace bottom plug-in electrode 4 is positioned on the all-electric melting furnace pool bottom 5, the all-electric melting furnace electrode 6 is positioned on the all-electric melting furnace pool wall 7, the all-electric melting furnace pool wall 7 is positioned at the top of the all-electric melting furnace pool bottom 5, the all-electric melting furnace crown 8 is positioned at the top of the all-electric melting furnace pool wall 7, and the all-electric melting furnace liquid flow hole 10 is located at the outlet of the all-electric melting section 1.

[0054] Furthermore, the smoke exhaust port 12 of the clarification section and the all-oxygen spray gun 13 of the clarification section are both located on the breast wall 16 of the clarification section, the top of the clarification section 14 is located at the top, the bridge-type retaining dam 23 of the clarification section is located in the middle section of the bottom, the ascending way 11 of the clarification section is located in the feeding section of the all-oxygen high-temperature clarification section 2, the all-oxygen spray gun 13 of the clarification section is installed on the all-oxygen spray gun installation port 29 of the clarification section, and the top discharge port 28 of the clarification section is opened on the flat yoke 30 of the clarification section ear pool.

[0055] Furthermore, the first cooling section discharge port 22 is located at the bottom of the cooling section brick channel 17, the cooling section platinum stirring mechanism 18 is located inside the cooling section brick structure 20, and the second cooling section discharge port 21 is located at the bottom of the cooling section platinum stirring mechanism 18, and the cooling section platinum channel 19 is located in the cooling section brick structure 20.

[0056] Furthermore, the all-electric melting furnace inside the all-electric melting section 1 adopts a cold top vertical melting structure, and the flow hole structure inside the all-electric melting section 1 is extended to the middle of the all-electric melting section 1 and reaches the center line position, so that the glass liquid on the flow hole side and away from the flow hole side can enter the flow hole as evenly as possible.

[0057] Aiming at the shortcomings of the two existing borosilicate glass melting furnaces, in order to improve the glass clarification effect, reduce the volatilization of boron in the glass raw materials, and meet the requirements of energy conservation and environmental protection, a three-stage high borosilicate glass melting device was invented. On the basis of energy saving, it reduces the volatilization of boron, meets the high-temperature clarification of glass liquid, reduces the bubble content of glass and improves the degree of optical deformation of glass.

[0058] The specific technical solutions are:

[0059] 1. The first stage: adopting the raw material melting technology of all-electric melting section, i.e. all-electric cold top

[0060] Currently, most cold-top electric glass melting furnaces operate entirely on electricity, with a continuous, even layer of batch material covering the entire surface of the melting pool. These fully electric melting furnaces utilize a "cold-top" vertical melting process. This layer of batch material covers the entire surface of the molten glass in the melting pool, blocking heat radiation from the melt toward the furnace roof and keeping the temperature in the upper chamber below 150°C. Simultaneously, most of the volatile components in the batch material condense in the layer and flow back into the glass. However, gases such as CO2 released during the melting process easily pass through the layer and into the upper chamber. The molten glass beneath the batch material layer slowly flows downward into the electrode area. Once fully melted in this area, the glass begins to clarify and then flows to the lower portion of the melting pool, completing the clarification and homogenization process. The molten glass enters the working chamber through the flow tunnel, riser, and feeder.

[0061] The all-electric melting furnace used in the production of borosilicate flat glass is also a cold-top electric melting furnace. Molybdenum electrodes are inserted along the sides of the pool wall and the bottom of the pool. This electrode layout causes the edge close to the pool wall to have a low temperature due to the heat dissipation of the pool wall. From the pool wall to the center, the electrode current is affected around the electrode to form the highest temperature area. However, in the middle of the electric melting furnace, due to the distance from the electrode, the temperature of the middle area is lower than that of the electrode area. Therefore, the entire electric melting furnace forms a cold core form of glass liquid melting. Under this temperature system, the entire electric melting furnace forms a liquid flow circulation in which the liquid flows upward in the electrode area and downward in the middle and along the edge of the pool wall. A direct consequence of this liquid flow circulation is that the rising flow in the electrode area will encounter the glass liquid that has not been clarified by high temperature after the upper glass raw material is melted, and will flow downward along the center of the electric melting furnace, making it difficult to clarify the bubbles in the glass liquid. This is also one of the important reasons why all-electric melting furnaces have more bubbles than all-oxygen combustion melting furnaces. In addition, since the flow hole is on one side of the electric melting furnace, relatively more molten glass enters the flow hole to form the forming flow, which also causes an imbalance in the melting rate between the side close to the flow hole and the side far away from the flow hole in the electric melting furnace, and also affects the overall melting efficiency and effect.

[0062] In order to achieve balanced liquid extraction from the all-electric melting furnace, the newly designed all-electric melting section adopts two improvement schemes. The first is to extend the flow hole structure to the middle of the all-electric melting section and reach the center line, so that the glass liquid on the side of the flow hole and away from the side of the flow hole can enter the flow hole as evenly as possible; the second is to increase the area of ​​the flow hole from the previous cross-sectional area of ​​300*400mm to 500*700mm. Increasing the cross-sectional area of ​​the flow hole reduces the flow velocity of the glass liquid in the flow hole, reduces the erosion of the glass liquid on the flow hole roof bricks, and increases the service life of the flow hole.

[0063] Selection of refractory materials for the all-electric melting section: Due to the use of a three-stage melting design, the maximum temperature of the all-electric melting section only needs to meet the melting of the raw materials, so the choice of refractory materials is relatively large. Generally, the melting section pool wall and pool bottom pavement are switched to 41 or 43 shrinkage-free electric-melted AZS bricks, and the top arch is made of high-quality silica bricks.

[0064] 2. The second section: Full oxygen high temperature clarification section Full oxygen combustion glass liquid clarification technology

[0065] The clarification of molten glass is the process of expelling microbubbles from the molten glass. The most critical factors affecting gas discharge are the temperature of the molten glass and the location of the bubbles. The design of the all-oxygen high-temperature clarifier utilizes the high-temperature flame temperature of all-oxygen combustion, while using electrodes to assist in heating the molten glass. This heats the borosilicate glass to above 1700°C, minimizing its viscosity and expelling bubbles. Depending on the melting capacity of the melting furnace, 2-6 pairs of all-oxygen spray guns can be installed. The type of spray gun with a reasonable flame coverage area is selected based on the width of the clarifier kiln pool. The exhaust gas from the flame combustion is discharged through a pair of exhaust ducts located on the breast wall at the front end of the clarifier. The cross-sectional area of ​​the exhaust duct is calculated based on the total amount of flue gas and the flue gas flow rate. Generally, the cross-sectional area of ​​the exhaust port is 0.1-0.4 square meters, and the flue gas flow rate is 5-20NM3 / min.

[0066] In the full-oxygen high-temperature clarification section, a bridge-type dam is set. The height of the dam accounts for 50%-70% of the depth of the glass liquid in the clarification section. The horizontal width of the upper surface of the dam is between 600-1500mm, and the distance between the upper surface of the dam and the glass liquid surface is 250-450mm. In this way, a hot spot area can be formed in the glass liquid at the dam, the depth of the glass liquid is small, and the bubbles inside the glass liquid can be fully released and emptied.

[0067] A discharge port is set in front of the bridge-type dam in the clarification section, which can continuously or intermittently discharge the aluminum-rich glass liquid accumulated in front of the dam due to stratification. The diameter of the discharge port ranges from φ15-φ30mm.

[0068] A pair of ear pools are set at the end of the clarification section to collect the silicon-rich glass liquid caused by boron volatilization. Overflow ports are set at the corners of the ear pools to discharge the silicon-rich glass liquid continuously or intermittently to ensure the quality of the glass liquid entering the cooling section. The overflow port and its size are designed based on the daily melting volume of the melting furnace and the boron content of the glass raw materials.

[0069] Multiple groups of bottom-inserted electrodes are set at the front end of the clarification section to directly heat the glass liquid temperature and improve thermal efficiency. Depending on the size of the clarification tank and the daily melting volume of the melting furnace, 2-6 groups of electrodes are set.

[0070] Selection of main refractory materials for full oxygen high temperature clarification section: The parts in contact with molten glass are preferably fused high zirconium bricks, and the crown and breast wall are selected from 33, 37, 41 or 43 shrinkage-free fused AZS bricks.

[0071] 3. The third section: Platinum forced stirring and homogenization and temperature-controlled cooling technology in the platinum channel cooling section

[0072] After high-temperature clarification, the glass liquid needs to be evenly cooled down to the temperature required for glass forming. This cooling process requires the glass liquid to be cooled from 1700℃ to 1300℃. In order to achieve the effect of forced stirring, a platinum stirring system and device are used. The glass liquid temperature at the platinum stirring position is around 1400℃. In order to meet the above requirements, a platinum channel cooling section is set. The key points are:

[0073] A brick channel is designed at the front end of the platinum channel cooling section to reduce the glass melt temperature and meet the platinum system's temperature requirements. The channel typically ranges from 3 to 6 meters in length, depending on the furnace's daily melting capacity. At its end, the glass melt temperature drops below 1500°C. The channel inlet utilizes a flow-hole design, with the top brick pressed into the glass melt to a depth of 100 to 300 mm. To facilitate connection to the platinum channel, the channel outlet features an upper closing design, reducing the cross-sectional area of ​​the entire channel by 65% ​​to 80%.

[0074] The platinum forehearth section is equipped with a platinum forced agitator and a platinum forehearth. The platinum forced agitator consists of a platinum barrel and a platinum stirrer. Molten glass enters from the top of the platinum agitator barrel and flows out from the bottom into the platinum channel. The entire platinum forehearth is electrically heated to control the cooling rate of the molten glass and the temperature difference between the inside and outside, ensuring that the molten glass entering the forming area is homogeneous in composition and temperature.

[0075] In the platinum material channel section, two discharge ports are set, one is before the brick material channel closes, and the other is below the platinum stirring. Intermittent or continuous discharge methods can be used to remove the deposited aluminum-rich sediment.

[0076] 4. The design of the three-stage high-borosilicate glass melting device is suitable for melting high-melting-point, high-volatility, and easily stratified glass. The all-electric melting section solves the high volatility of the volatile components of the raw materials and reduces the volatility of the volatile components to below 1%; the use of the all-oxygen high-temperature clarification section solves the problem of clarification of high-melting-point glass and ensures that the bubbles in the glass are fully discharged; the top discharge port and bottom discharge port set at the corresponding positions of the melting device solve the stratification problem of easily stratified glass, and timely discharge the component enrichment layer caused by volatilization and stratification, ensuring the qualified and stable composition requirements of the glass products.

[0077] The design of the three-stage high borosilicate glass melting device also has a broad spectrum and is applicable to the production of highly volatile lead glass, high melting point borosilicate zirconium yttrium lanthanum glass, high aluminum glass, borosilicate colored glass, etc.

[0078] 1. Main design parameters of a borosilicate glass melting furnace with a daily melting capacity of 50 tons / day

[0079] To produce high borosilicate flat glass, the daily melting rate is 50 tons. The boron content in the glass is about 12%, the aluminum content is 2.5%, the overall boron volatilization of the melting furnace is controlled within 3%, and the average daily discharge volume is less than 3 tons. The design is as follows:

[0080] The first all-electric melting section features a 12-sided design, a 2.2-meter-deep melting pool, a 6.4-meter-diameter melting pool, and a melting area of ​​32 square meters. The daily melting rate is 1.56 tons / square meter. The pool walls are heated using three layers of six groups of 54 electrodes, while the bottom is heated using a circle of six groups of 12 electrodes, all with a 63mm diameter molybdenum electrode. The flow channel is 700mm wide and 500mm high, extending from the center of the melting pool to the centerline. The pool walls and bottom are paved with 43-grade, shrinkage-free AZS, and the ceiling is suspended and installed using high-quality silica bricks.

[0081] The second section of the full-oxygen high-temperature clarification section has a glass liquid pool with a depth of 972mm, a length of 9018mm, and a width of 2540mm. The top surface of the bridge-type retaining dam is 1219mm wide and 686mm high. The clarification section is provided with 3 rows and 9 groups of 18 molybdenum electrodes with an electrode diameter of 51mm. A discharge port with a diameter of 25mm is provided in front of the bridge-type retaining dam. A pair of ear pools are provided at the end of the clarification section with an inner size of 889*1092mm. A top discharge port is provided above the ear pool. A total of 8 full-oxygen spray guns are provided on both sides of the breast wall of the clarification section, with a staggered layout, and the spray guns are installed at a 30-degree angle to the inside of the clarification section (see Figure 3 Clarification section oxygen spray gun layout diagram), spray gun selection The 52G600 pure oxygen burner uses natural gas as fuel and oxygen as the combustion aid. A pair of exhaust ports, each with a cross-sectional area of ​​0.24 square meters, are located on the breast wall of the clarifier, near the melting section. The entire clarifier tank, where it comes in contact with the molten glass, is constructed entirely of fused high-zirconium bricks. The breast wall and crown are constructed of 43-grade, shrinkage-free fused AZS.

[0082] The third section of the platinum channel, with a 3048mm long brick channel at the front end of the cooling section, is constructed entirely of fused high-zirconium bricks. The channel's inlet cross-section measures 762*1168mm, narrowing to 381*406mm at the outlet, where it connects to the platinum channel. The platinum mixing drum has a diameter of 508mm and a depth of 889mm. The distance between the mixing blades and the inner wall of the drum is no more than 25.4mm. The channel, exiting the drum, is 2540mm long and has a cross-section of 0.093 square meters.

[0083] 2. Production Example 1: Production of borosilicate 3.3 glass

[0084] Borosilicate 3.3 glass has a boron content of approximately 13.9%, a melting point of 1316°C, and a clarification temperature of 1650°C. Production data recorded on four different dates are as follows:

[0085]

[0086] Production Example 2: Production of borosilicate 2.6 glass

[0087] Borosilicate 2.6 glass has a boron content of approximately 10.8%, a melting point of 1458°C, and a clearing temperature of 1715°C. The production data recorded on three different dates are as follows:

[0088]

[0089] Working principle: The utility model includes an all-electric melting section 1, an all-oxygen high-temperature clarification section 2, a platinum material channel cooling section 3, an all-electric melting furnace bottom plug electrode 4, an all-electric melting furnace pool bottom 5, an all-electric melting furnace electrode 6, an all-electric melting furnace pool wall 7, an all-electric melting furnace crown 8, an all-electric melting furnace liquid level 9, an all-electric melting furnace flow hole 10, a clarification section riser 11, a clarification section smoke exhaust port 12, a clarification section all-oxygen spray gun 13, a clarification section crown 14, a clarification section liquid level 15, a clarification section breast wall 16, a cooling section brick material channel 17, a cooling section platinum stirring mechanism 18, a cooling section platinum material channel 19, a cooling section Brick structure 20, second cooling section discharge port 21, first cooling section discharge port 22, clarification section bridge dam 23, clarification section discharge port 24, clarification section bottom plug electrode 25, all-electric melting furnace discharge port 26, clarification section pool wall 27, clarification section top discharge port 28, clarification section full oxygen spray gun installation port 29 and clarification section ear pool flat 30. The melting production of high borosilicate glass has the characteristics of high melting point, large boron volatility, high viscosity, and easy stratification. The production is very difficult. In order to solve these difficulties in the production of high borosilicate glass, a new production line has been developed and designed. The main technical points are:

[0090] 1. Breaking the traditional design concept of electric melting furnace, an all-oxygen high-temperature clarification section is added between the electric melting furnace and the horizontal material channel, so that the entire melting furnace is divided into three parts: the all-electric melting section, the all-oxygen high-temperature clarification section, and the platinum material channel cooling section.

[0091] 2. The melting section of the all-electric cold-top electric melting furnace is loaded from the top of the furnace, and the raw materials are heated and melted from top to bottom. When the raw material layer thickness reaches 800-150mm, it not only ensures that the high-temperature heat in the melting furnace is not lost, but also effectively controls the volatilization of boron, keeping the volatilization rate of boron in the all-electric melting furnace to less than 1%. The use of side-inserted electrodes and bottom-inserted electrodes to coordinate the heating of the glass liquid achieves a thermal efficiency of over 85%, achieving the goal of energy conservation and emission reduction.

[0092] 3. The all-oxygen high-temperature clarification section, compared with the traditional all-electric melting furnace glass production line, adds an all-oxygen high-temperature clarification section between the electric melting furnace and the horizontal material channel. Bottom-inserted electrodes are installed in the glass liquid in the clarification section, and multiple groups of all-oxygen burners are installed in the upper space of the glass liquid. The structure is equipped with a bridge-type dam and a bottom discharge hole to further heat the glass liquid coming from the all-electric melting furnace, reduce the viscosity, and fully eliminate the bubbles in the glass liquid to achieve the ideal clarification effect. In particular, the application of the bridge-type dam can completely reduce the temperature difference between the inside and outside of the glass liquid, so that the glass liquid can be clarified while being well homogenized in temperature and composition.

[0093] 4. The platinum channel cooling section ensures that the glass liquid can be cooled synchronously inside and outside during the cooling process, avoiding the temperature difference between the middle and the periphery, and also reducing the contamination of the refractory material to the glass liquid.

[0094] 5. In the full-oxygen high-temperature clarification section, a pair of continuous discharge ports are symmetrically set at the top to discharge the silicon-rich glass liquid on the surface caused by boron volatilization, thereby reducing the formation of siliceous stones and carbuncle; in the full-oxygen high-temperature clarification section, a pair of continuous flue gas exhaust ports are symmetrically set at the front end of the breast wall to discharge the exhaust generated by full-oxygen combustion.

[0095] 6. Discharge ports are set at the end of the liquid flow tunnel of the all-electric melting furnace, the front end of the bridge-type dam of the clarifier, the climbing part of the brick channel of the cooling section, and the bottom of the platinum channel. These ports can continuously or intermittently discharge the aluminum-rich deposits produced by stratification, thereby avoiding optical deformation and quality problems of the glass plate caused by uneven composition.

[0096] 7. The use of platinum stirring and platinum material channel with heating function can effectively achieve controllable cooling, that is, to achieve uniform and homogeneous cooling inside and outside the glass liquid during the cooling process, ensuring that the glass liquid entering the tin bath for forming meets the homogenization requirements in terms of composition and temperature.

[0097] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements shall fall within the scope of the present invention as claimed.

Claims

1. A three-stage borosilicate glass melting furnace, comprising an all-electric melting section (1), an all-oxygen high-temperature clarification section (2) and a platinum material channel cooling section (3), characterized in that: The full oxygen high temperature clarification section (2) is located on one side of the full electric melting section (1), and the platinum channel cooling section (3) is located on one side of the full oxygen high temperature clarification section (2); The all-electric melting section (1) comprises an all-electric melting furnace bottom plug electrode (4), an all-electric melting furnace pool bottom (5), an all-electric melting furnace electrode (6), an all-electric melting furnace pool wall (7), an all-electric melting furnace crown (8), an all-electric melting furnace liquid surface (9), an all-electric melting furnace liquid flow hole (10) and an all-electric melting furnace discharge port (26); The full-oxygen high-temperature clarification section (2) comprises a clarification section ascending path (11), a clarification section smoke exhaust port (12), a clarification section full-oxygen spray gun (13), a clarification section crown (14), a clarification section liquid surface (15), a clarification section breast wall (16), a clarification section bottom plug-in electrode (25), a clarification section discharge port (24), a clarification section bridge dam (23), a clarification section pool wall (27), a clarification section top discharge port (28), a clarification section full-oxygen spray gun installation port (29) and a clarification section ear pool flat crown (30); The platinum channel cooling section (3) comprises a cooling part brick channel (17), a first cooling part discharge port (22), a second cooling part discharge port (21), a cooling part platinum stirring mechanism (18), a cooling part platinum channel (19) and a cooling part brick structure (20).

2. A three-stage high borosilicate glass melting furnace according to claim 1, characterized in that: The all-electric furnace bottom plug electrode (4) is positioned on the all-electric furnace pool bottom (5), the all-electric furnace electrode (6) is positioned on the all-electric furnace pool wall (7), the all-electric furnace pool wall (7) is positioned on the top of the all-electric furnace pool bottom (5), the all-electric furnace crown (8) is positioned on the top of the all-electric furnace pool wall (7), and the all-electric furnace liquid flow hole (10) is located at the outlet of the all-electric melting section (1).

3. The three-stage high borosilicate glass melting furnace according to claim 1, characterized in that: The smoke exhaust port (12) of the clarification section and the all-oxygen spray gun (13) of the clarification section are both located on the breast wall (16) of the clarification section, the top of the clarification section (14) is located at the top, the bridge-type retaining dam (23) of the clarification section is located in the middle section of the bottom, the ascending path (11) of the clarification section is located in the feeding section of the all-oxygen high-temperature clarification section (2), the all-oxygen spray gun (13) of the clarification section is installed on the all-oxygen spray gun installation port (29) of the clarification section, and the top discharge port (28) of the clarification section is opened on the flat purlin (30) of the clarification section.

4. The three-stage high borosilicate glass melting furnace according to claim 1, characterized in that: The first cooling section discharge port (22) is located at the bottom of the cooling section brick channel (17), the cooling section platinum stirring mechanism (18) is located inside the cooling section brick structure (20), and the second cooling section discharge port (21) is located at the bottom of the cooling section platinum stirring mechanism (18), and the cooling section platinum channel (19) is located in the cooling section brick structure (20).

5. The three-stage high borosilicate glass melting furnace according to claim 1, characterized in that: The all-electric melting furnace inside the all-electric melting section (1) adopts a cold top vertical melting structure, and the flow hole structure inside the all-electric melting section (1) is extended to the middle of the all-electric melting section (1) and reaches the center line position, so that the glass liquid on the side of the flow hole and away from the side of the flow hole can enter the flow hole as evenly as possible.

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