Melting equipment

Abstract

The present invention relates to a melting apparatus (100) including a melting space bounded by at least a bottom wall (120) and a side wall (130), the melting space being used to melt a material within the melting space. The melting apparatus further includes at least one submerged burner (F) and at least one electric heater (E) disposed within the melting space for heating the material.

Description

[Technical Field]

[0001] The present invention relates to the field of material melting, and in particular to melting devices, such as melting furnaces or kilns, for melting materials such as glass and metals. [Background technology]

[0002] The conventional method for melting materials is to use a burner to heat and melt the materials in a melting device (e.g., a melting furnace). A burner is a device that converts oxidizers and fuels into thermal energy through a chemical reaction of combustion. Traditionally, burners employ flame radiation heating or indirect heating (where the heat of flame combustion is transferred to the heated material through a heat transfer medium), and have the characteristics of high heat radiation, low thermal efficiency, and high energy consumption.

[0003] Typically, taking glass melting as an example, glass is made from a mixture of raw materials such as silicates, basalt, limestone, soda ash, and minor amounts of other ingredients. To melt glass, these raw materials are introduced into a glass melting furnace and melted to a liquid state at temperatures between approximately 1250°C and 1500°C. The melt is then subjected to a forming process. Depending on the intended use of the melt, e.g., glass or fiber, in various applications, additional melting and fining steps are performed before the forming process. Conventional glass melting furnaces include a burner that generates a flame in the space between the surface of the glass melt and the top of the furnace, and heat is transferred to the glass melt by radiation from the upper material and the flame itself. A large amount of energy is consumed during the heat transfer process. In high-temperature manufacturing processes such as glass melting, the above-mentioned problems associated with conventional burner flame heating methods, such as high heat radiation, low thermal efficiency, and high energy consumption, become even more severe.

[0004] In recent years, CO2 emissions have become a major topic that has attracted widespread attention in the international community. Everyone is working hard to find solutions to reduce CO2 emissions, and one of the main approaches is to reduce CO2 emissions by reducing energy consumption and increasing energy efficiency.

[0005] As one solution to reducing emissions, melting or processing materials (such as glass, metal, and solid waste, hereinafter, glass will be used as an example) by electrical heating is an obvious approach. As used herein, the term "electrical heating" refers to a heating method in which electrical energy is converted into thermal energy in a heated medium, such as a glass liquid, by a device such as an electrode using electricity as an energy source. In this method, the heated medium is heated through an electrical conduction process. Electrical heating directly heats the heated medium and does not involve the combustion of fuel, resulting in high thermal efficiency, low heat loss, and low emissions. However, during the process of electrical heating using electrodes, a segregation phenomenon of ions (i.e., negative ions in the glass melt collect at the anode, while positive ions collect at the cathode) occurs in the glass melting furnace. This makes it difficult to form a desired melt flow for homogenizing the glass melt in the glass melt, ultimately resulting in failure to obtain high-quality glass products. Furthermore, the segregation of ions further exacerbates the corrosion of refractories in the glass melting furnace. In addition, the high cost of the electrical heating method is also a factor hindering its application and widespread replication.

[0006] Another solution to reducing emissions is submerged combustion, in which submerged burners are typically placed below the surface of the glass frit. Submerged burners can be mounted on the sidewalls and / or bottom of the glass melting furnace. Some submerged burners can be mounted on the top of the furnace, but their nozzles are immersed in the glass melt. With submerged burners, the flame and combustion products generated by the combustion of fuel and oxidizer pass through the glass melt and directly contact the melt, resulting in more effective heat transfer than radiative heating with a flame above the melt surface. This reduces heat transfer to the refractories in the glass melting furnace and heat loss in the flue gas. This reduces fuel consumption and, therefore, CO2 emissions. Additionally, NOx emissions are also reduced during the combustion process due to the lower temperature in the combustion chamber above the glass melt. Furthermore, the high flow rate of combustion products generated by the oxidizer and fuel enters the glass melt, and the gas generated during the submerged combustion process expands, rapidly melting the glass frits and creating significant turbulence, thus facilitating uniform mixing of the molten glass. This eliminates or reduces the need for mechanical stirrers, and heat transfer between the low-temperature melt and the high-temperature melt is more effective. Furthermore, compared with conventional burners placed above the glass melt, submerged burners are smaller in size, have higher production efficiency, and reduce the installation costs of the melting furnace. However, while submerged combustion generates significant turbulence in the glass melt, it also has a high potential for the generation of various types of bubbles (large and fine). The generation of bubbles adversely affects the quality of the final glass, often necessitating additional post-processing to obtain glass products of satisfactory quality. Of course, if the requirements for bubble content are lower (e.g., there may be more than 10 bubbles greater than 0.1 mm in diameter per 100 grams of glass), the requirements for such additional post-processing may be reduced, but only for the final product with the lower bubble content requirements. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is an object of the present invention to overcome at least one of the above-mentioned problems and / or other drawbacks in the prior art. [Means for solving the problem]

[0008] The present invention provides a melting device including a melting space within which a material can be melted, the melting space being surrounded by at least a bottom wall and a side wall, the melting device further including at least one electric heater and at least one submerged burner disposed within the melting space for heating the material.

[0009] According to an exemplary embodiment of the present invention, the submerged burners and electric heaters may be configured so that a hot spot in the melting space is located downstream of the submerged burners in the melt flow direction, which is the direction in which the material melt flows through and is released from the melting space.

[0010] According to an exemplary embodiment of the present invention, the submerged burner may be disposed upstream of the electric heater in the melt flow direction in which the material melt flows through and is discharged from the melt space.

[0011] According to an exemplary embodiment of the present invention, the submerged burners and electric heaters may be configured so that 50% or more, preferably 70% to 80%, of the energy used to heat and melt the material is provided by the electric heaters, and less than 50%, preferably less than 20%, is provided by the submerged burners.

[0012] According to an exemplary embodiment of the present invention, the melting apparatus may further include a burner positioned above the surface of the material melt, the burner configured to provide a portion of the energy used to heat and melt the material other than the energy provided by the submerged burner and the electric heater, said portion being, for example, 10%.

[0013] According to an exemplary embodiment of the present invention, the submerged burner may be configured such that the fuel and oxidant supplied to the submerged burner are divided into a first portion that is continuously supplied and a second portion that is intermittently supplied, the flow rate of the first portion being less than the flow rate of the second portion, and preferably the flow rate ratio between the first portion and the second portion being adjustable, and / or the supply frequency and / or supply duration of the second portion being adjustable.

[0014] According to an exemplary embodiment of the present invention, the submerged burner may use hydrogen as a fuel.

[0015] According to an exemplary embodiment of the present invention, the at least one submerged burner may include a plurality of submerged burners protruding from the bottom wall into the material melt, the heights to which the plurality of submerged burners protrude from the bottom wall increasing in the melt flow direction.

[0016] According to an exemplary embodiment of the present invention, the bottom wall upstream of the electric heater may include a plurality of protrusions that protrude into the material melt, the heights of the plurality of protrusions increasing in the melt flow direction.

[0017] According to an exemplary embodiment of the present invention, a submerged burner may extend from an upper end of each said projection.

[0018] According to an exemplary embodiment of the present invention, coolant nozzles or piping for cooling the submerged burners may be housed within the protrusion.

[0019] According to an exemplary embodiment of the present invention, the at least one submerged burner may include two or more submerged burners that may share a cooling system and / or a system for supplying fuel and oxidant.

[0020] According to an exemplary embodiment of the present invention, the material melt may be molten glass, molten metal, molten resin, or solid waste in a molten state.

[0021] According to an exemplary embodiment of the present invention, the submerged burner may include a fuel passage and an oxidizer passage configured to discharge the fuel and the oxidizer, respectively, outside the submerged burner so that the fuel and the oxidizer mix outside the submerged burner.

[0022] According to an exemplary embodiment of the present invention, at least one of the fuel passage and the oxidant passage may be configured to form a swirl flow of the released fuel and / or oxidant.

[0023] The melting apparatus according to the present invention provides at least the following technical effects: by combining electrical heating and submerged combustion to melt and heat materials, unexpected results are obtained, thereby enhancing the strengths of the two heating methods while compensating for their weaknesses: first, the problem of ion group segregation in the electrical heating method is alleviated, thereby using submerged combustion to increase the homogenization level of the glass liquid; second, the problem of gas bubbles in the submerged combustion method is eliminated by electrical heating, while at the same time maintaining the inherent advantages of these two heating methods as much as possible, thereby providing a production apparatus and method for obtaining high-quality products of material melting at low cost.

[0024] Various features and advantages of the present invention will be described in detail below through non-limiting embodiments with reference to the drawings. Here, the drawings are merely schematic and are not necessarily drawn to scale. In addition, the drawings show only parts necessary to explain the present invention, and other parts may be omitted or mentioned only in simple terms. That is, in addition to the components or main elements shown in the drawings, the present invention may also include other components or main elements. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a cross-sectional view of a melting device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal cross-sectional view of a melting device according to an embodiment of the present invention. [Figure 3]FIG. 3 is a longitudinal cross-sectional view of a melting device according to another embodiment of the present invention. [Figure 4] FIG. 4 is a partial longitudinal cross-sectional view of a melting device according to another embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram of a submerged burner used in a melting apparatus according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram of a submerged burner assembly used in a melter according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Exemplary embodiments of the present invention are described in detail below with reference to the drawings. In the following description, numerous specific details are set forth to provide those skilled in the art with a more comprehensive understanding of the present invention. However, as will be apparent to those skilled in the art, the present invention may be practiced without some of these specific details. It should also be understood that the present invention is not limited to the specific embodiments presented. Rather, it is conceivable to practice the present invention using any combination of the features and key elements described herein, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages serve only as illustrative purposes and should not be considered key elements or definitions of the claims unless explicitly recited in the claims.

[0027] In the following description of specific embodiments, it should be understood that the orientations or positional relationships indicated by terms such as "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" are based on the orientations or positional relationships shown in the drawings, and do not represent or imply that the referenced devices or elements must have a specific orientation or be constructed or operated in a specific orientation, but are merely intended to facilitate and simplify the description of the present invention, and therefore should not be construed as limiting the present application.

[0028] Additionally, the terms "first" and "second" are used solely for descriptive purposes and should not be construed as indicating or suggesting relative importance or as implicitly specifying the quantity of the indicated technical features. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more than two, unless expressly specified otherwise.

[0029] As used herein, the term "fuel" refers to a gaseous fuel, a liquid fuel, or a solid fuel, which may be used interchangeably or in combination with one another. If the fuel is at least partially gaseous, it may be introduced directly into the burner. If the fuel is liquid or solid, it is introduced near the burner. The gaseous fuel may be natural gas (mainly methane), propane, hydrogen, syngas, biomass gas, or any other hydrocarbon and / or sulfur-containing and / or nitrogen-containing compound. The solid or liquid fuel may be any compound primarily in carbon-containing and / or hydrocarbon and / or sulfur-containing form. Those skilled in the art can determine how the gaseous, liquid, or solid fuel is introduced as needed. It is not the purpose of the present invention to impose any limitations in this regard.

[0030] As used herein, the term "nozzle" refers to a component positioned at the tip of a burner through which fuel and oxidant are injected for combustion; the nozzle may be a separate component or may be integrally formed with another component.

[0031] As used herein, the terms "melting" and "melting" include the act of heating a heated medium from a substantially solid state to a substantially liquid state.

[0032] As used herein, the term "melt" or "molten material" refers to a substance obtained by melting, which may contain inorganic components, metals, or organic components, and may be molten glass, molten metal, molten resin, molten waste, or the like.

[0033] As used herein, the terms "glass melt" and "glass liquid" refer to a composition for producing a glass product. The composition can exist in any state between a substantially solid state and a substantially liquid state, including a substantially solid state and a substantially liquid state. Such a state is between the raw materials and the molten glass (including the raw materials and the molten glass), including any degree of partial melting between the raw materials and the molten glass.

[0034] As used herein, the term "axial" refers to the direction of an axis of rotation, axis of symmetry, or approximate centerline that is substantially parallel to the direction of the central axis of the burner.

[0035] In the following description, glass frit is used as an example of the heated material, but those skilled in the art will understand that the heated material can be any other material that needs to be heated to melt, such as metal, solid waste, or other solid materials.

[0036] 1 and 2 are schematic diagrams of a melting apparatus (shown here as a glass melting furnace for example) according to an embodiment of the present invention. In the glass melting furnace 100, glass frits are introduced into the furnace through a feed port (not shown), and then heated and melted to form a glass melt or glass liquid, which, after undergoing some clarification and homogenization, is finally discharged from an outlet 110 shown in FIG. 2 for subsequent process steps, such as post-processing or forming.

[0037] The glass melting furnace 100 may include a melting space surrounded by at least a bottom wall and side walls, and the glass frit is heated and melted in the melting space. In the illustrated embodiment, the melting space is, for example, a substantially rectangular parallelepiped-shaped space surrounded by a bottom wall 120 and four side walls 130. FIG. 1 is a cross-sectional view along a direction parallel to the short side walls of the rectangular parallelepiped, and FIG. 2 is a longitudinal cross-sectional view along a direction parallel to the long side walls of the rectangular parallelepiped. As shown in FIG. 2, the outlet 110 is located at the bottom of one of the short side walls of the rectangular parallelepiped, while the supply port is located near the other short side wall opposite the short side wall. Therefore, the glass frit Y just fed into the furnace gathers near the other short side wall. As the glass frits continue to melt, the glass melt forms a melt surface (liquid surface) S in the melting space, flows generally toward the outlet 110, and is finally discharged from the melting space through the outlet 110, the melt flow direction thus formed being parallel to the long side wall of the melting space and substantially from left to right in Fig. 2. Accordingly, positions or regions adjacent to the left side of Fig. 2 and away from the outlet 110 are upstream in the melt flow direction, while positions or regions adjacent to the right side and close to the outlet 110 are downstream in the melt flow direction.

[0038] To heat and melt the glass raw materials, the glass melting furnace 100 includes at least one submerged burner F and at least one electric heater E. In FIG. 1 , multiple submerged burners F are shown on the left side of the longitudinal center plane P of the glass melting furnace 100. The multiple submerged burners F may be in the general form of thermal spray lances, for example, arranged on the bottom wall 120 of the glass melting furnace 100 and extending upward from the bottom wall 120 into the glass melt. Combustion of fuel and oxidizer is generated from nozzles at the tips of the submerged burners, and the resulting flame and combustion products pass through the glass melt and directly contact the glass melt, achieving a good heating effect. One or more submerged burners F may also be provided on the side wall of the glass melting furnace 100. In FIG. 1 , multiple electric heaters E are shown on the right side of the longitudinal center plane P of the glass melting furnace 100. The multiple electric heaters E may be realized using electrodes, for example. In the illustrated embodiment, the electric heater E may include a plurality of electrode rods E1 extending from the bottom wall 120 of the glass melting furnace into the glass melt, and optionally a plurality of electrode plates E2 disposed on the side wall 130 of the glass melting furnace. When energized, the electric heater E generates heat by an electric current formed by conductive ions in the glass melt to directly heat the glass melt.

[0039] In the present invention, two heating methods, specifically, a submerged burner F and an electric heater E, are used in combination in a glass melting furnace to melt glass raw materials. Therefore, first, the submerged burner F generates numerous large and small bubbles while in operation, causing significant turbulence in the glass melt. This not only achieves the beneficial effect of clarifying and homogenizing the glass melt in the melting space (which reduces the need for mechanical stirrers, e.g., replacing bubblers or other stirring devices commonly used in glass production), but also tends to form or promote a glass melt flow in the melting space. This promoted glass melt flow is suitable for contributing to reducing the segregation of ions generated around the electric heater E. Eliminating the problem of ion segregation can enhance the glass homogenization effect in the area of ​​the electric heater E to improve the quality of the final glass product, and can also reduce the erosion of the refractories in the melting furnace, thereby extending the service life of the melting furnace. Secondly, after reaching the area of ​​electric heater E, the molten glass flowing within the melting space and containing bubbles is subjected to the high-temperature heating effect brought about by electric heater E due to the action of the submerged burner. This high-temperature heating effect causes the bubbles in the molten glass to rise to the glass surface and escape, thereby reducing the bubble content in the molten glass and helping to improve the quality of the final glass product.

[0040] As can be seen, the heating method that combines a submerged burner with an electric heater suppresses the major drawbacks inherent in these two heating methods, while at the same time maintaining the advantages of submerged combustion and electric heating (high heating efficiency, low heat loss, low heat radiation, high glass homogenization, etc.) and achieving a good balance in terms of cost.

[0041] In an embodiment, the submerged burners F and electric heaters E can be configured so that the high-temperature point in the melting space is located downstream of the submerged burners F in the melt flow direction. That is, the number of submerged burners F and electric heaters E, their output, and the arrangement of the submerged burners F and electric heaters E are controlled so that the peak temperature in the glass melting furnace occurs in the downstream region. Therefore, the bubble-containing molten glass flowing downstream from the region where the submerged burners F are installed toward the melting furnace outlet reaches a temperature peak in the downstream region, thereby enhancing or optimizing the bubble removal effect of the high temperature on the molten glass. An exemplary temperature curve C is shown above the glass surface S in FIG. 2 . As can be seen, the temperature in the glass melting furnace / melting space gradually increases from the upstream region toward the downstream direction to a peak value point (high-temperature point) K, and then gradually decreases toward the downstream direction. The region below point K may correspond to a location where multiple electric heaters E (electrodes) are concentrated. Before reaching point K, as the temperature gradually increases, gas bubbles in the glass melt continuously rise to the glass surface and become bubbles M, and the strongest bubble removal effect is achieved at point K, where the temperature is highest, after which the number of bubbles M and the gas bubbles can be significantly reduced. Of course, those skilled in the art will understand that if the requirements for the gas bubble content in the produced glass product are low (e.g., the number of gas bubbles with a diameter of more than 10 per 100 grams of glass may be more than 10), the hot spot in the melting space may also be located upstream of the submerged burner F in the melt flow direction. In this case, the bubble removal effect of the hot spot on the glass melt flowing generally downstream toward the melting furnace outlet is generally inferior to the bubble removal effect in a system in which the hot spot is located downstream of the submerged burner. However, this bubble removal effect may still be useful for removing gas bubbles from the glass melt that locally flows backward, and this bubble removal effect is sufficient for use in scenarios where the requirements for the gas bubble content are not high.

[0042] In an embodiment, as shown in FIGS. 2 and 3 , the submerged burners F may be disposed upstream of the electric heater E in the melt flow direction. Therefore, the submerged burners F disposed in the upstream region tend to promote the glass melt flow, which originally flowed generally downstream toward the melting furnace outlet, due to turbulence and the resulting bubbles. After reaching the downstream region, this promoted glass melt flow can more effectively reduce the segregation of ions generated around the electric heater E in the downstream region. Furthermore, disposing the electric heater E downstream of the submerged burners F helps create a condition in the melting space in which the temperature gradually increases downstream until a hot spot is reached. Therefore, when the glass melt containing bubbles flows generally downstream from the upstream region where the submerged burners F are located, the temperature increase and hot spot provided by the heater can more effectively remove the bubbles. Naturally, the present invention is not limited to a configuration in which the submerged burners are disposed upstream of the electric heater. The submerged burners may also be arranged downstream of the electric heater, but in this case the effectiveness in terms of eliminating ion segregation and removing bubbles is inferior to that of the arrangement in which the submerged burners are arranged upstream of the electric heater, but this effectiveness is suitable for scenarios in which the requirements regarding the quality of the glass product are not very high. Alternatively, in situations in which multiple submerged burners F and / or electric heaters E are provided, the submerged burners and electric heaters may also be arranged alternately with each other in the melt flow direction.

[0043] In an embodiment, the submerged burners F and the electric heaters E are configured so that 50% or more, preferably 70% to 80%, of the energy used to heat and melt the glass frit is provided by the electric heaters E, and less than 50%, preferably less than 20%, e.g., 15%, is provided by the submerged burners. That is, the electric heaters are used as the primary heat source for melting the glass, and the submerged burners function as a secondary heat source. Research has shown that if the heat share of submerged combustion is too high, numerous bubbles appear in the glass melt, and even downstream electric heating is difficult to remove these bubbles to a satisfactory level, which is detrimental to the quality of the final glass product or requires additional post-processing steps to remove the bubbles in order to obtain a glass product of the desired quality. Those skilled in the art will understand that if the bubble content requirement in the produced glass product is low (e.g., when preparing glass wool, glass fiber filaments for insulation, etc., the number of bubbles exceeding 0.1 mm in diameter may be more than 10 per 100 grams of glass, in which case the requirement for additional post-processing of the glass liquid may be reduced) or if an additional bubble post-processing step is performed downstream of the glass melting furnace, the heat proportion accounted for by submerged combustion may appropriately be slightly increased or otherwise slightly decreased. As shown in FIG. 1 , in addition to the submerged burner F and electric heater E, a conventional burner R may also be provided as an auxiliary heat source in the space between the glass liquid level S and the upper arched crown 140 of the glass melting furnace 100. The flame emitted by this burner is used to radiate heat materials near the glass liquid level S to achieve a better melting effect and control the temperature and atmosphere in the space above the glass liquid level. Accordingly, the burner R is configured to provide a portion of the energy used to heat and melt the glass other than the energy provided by the submerged burner F and the electric heater E, this portion being, for example, 10%.

[0044] In an embodiment, one or more submerged burners F may be configured such that the fuel and oxidizer supplied to the submerged burners F are divided into a first portion that is continuously supplied and a second portion that is intermittently supplied. That is, one portion of the fuel and oxidizer (the first portion) is continuously supplied to the submerged burners, while the other portion of the fuel and oxidizer (the second portion) is pulsed to the submerged burners only at first predetermined time intervals and supplied for a second predetermined duration. The function of the continuously supplied first portion of the fuel and oxidizer is to maintain the flame of the submerged burners and prevent the glass melt from flowing back into the nozzle of the submerged burners. Therefore, the flow rate (pressure) of the first portion may be less than the flow rate (pressure) of the second portion. The intermittently supplied second portion of the fuel, oxidizer, and corresponding combustion products may enhance the stirring and mixing effect on the glass melt, thereby improving the homogenization level of the glass melt. In addition, compared to continuous supply of fuel and oxidizer at high flow rates, this type of pulsed intermittent supply can avoid or reduce violent collisions and explosions between combustion gases and between generated bubbles, thereby reducing the possibility of numerous small bubbles that are difficult to remove being formed due to fragmentation in the glass melt and helping to reduce the porosity rate in the final glass product. Preferably, the flow rate ratio of the first and second portions of fuel and oxidizer supplied is adjustable, and / or the supply frequency (determined by the first predetermined duration mentioned above) and / or the supply duration (i.e., the second predetermined duration mentioned above) of the second portion of fuel and oxidizer are adjustable. Therefore, the generation of bubbles in the glass melt can be adaptively suppressed according to different scenarios and requirements.

[0045] Advantageously, the submerged burner F may use hydrogen as fuel. Hydrogen has many advantages as a clean energy source, but it has been found that when hydrogen is used as fuel, the hydrogen flame is not bright, has low radiance, and has low heat transfer efficiency during heating. Due to the characteristics of heat convection and conduction through direct contact in submerged combustion, the submerged burner can completely transfer the heat of the hydrogen flame to the heated material, thus better utilizing the thermal energy of hydrogen combustion. The use of hydrogen as fuel for the submerged burner also has the following advantages: since the only product of the oxidative combustion of hydrogen is water, the CO2 emissions generated during the combustion process can be reduced; in addition, for example, glass melts need to be clarified to remove bubbles therein. However, when hydrogen is used as fuel, the partial pressure of the gaseous water produced is different from the partial pressures of other gases present in the glass. As a result, these gas bubbles are more easily absorbed and coalesce to form larger bubbles, which are then released. Furthermore, the large number of OH molecules produced by hydrogen combustion can be reduced. - However, hydrogen can reduce the tension on the glass surface around bubbles of various sizes, and this can make it easier for the gas in the bubbles to escape from the glass. All of these advantages of hydrogen make it suitable for use as a fuel for submerged burners during material melting.

[0046] In an embodiment, as shown in FIG. 3 , multiple submerged burners F projecting into the glass melt may be provided on the bottom wall 120 of the glass melting furnace 100, including multiple (three in the figure, for example) submerged burners F1, F2, and F3. The submerged burners F1, F2, and F3 project from the bottom wall, and the heights of the submerged burners F1, F2, and F3 increase in order in the melt flow direction (i.e., substantially from left to right in FIG. 3 ). This layout of multiple submerged burners helps to form a melt flow in the glass melt that gradually rises in the melt flow direction. This flow direction of the glass melt increases the flow path of the glass melt in the melting space, thereby helping to extend the duration of clarification and homogenization of the glass melt. Furthermore, the flow of the glass melt containing gas bubbles that gradually rises toward the glass melt surface S also significantly contributes to the escape of gas bubbles from the glass melt surface S. Those skilled in the art will understand that by appropriately setting the projection height and spacing of the submerged burners and their power ratios to each other, it is also possible to create a glass melt flow along other suitable paths within the melting space as needed.

[0047] As an alternative or additional solution to the above-described layout for arranging submerged burners F1, F2, and F3, multiple protrusions C1, C2, and C3 (shown as three in the figure as an example) protruding into the glass melt may also be provided on the bottom wall 120 in the upstream region of the glass melting furnace 100, as shown in Fig. 4, with the heights of the multiple protrusions increasing in order in the melt flow direction. Similarly, such a configuration can generate a melt flow that gradually rises in the melt flow direction and achieve the same effect as the above-described layout for arranging submerged burners shown in Fig. 4. In such a configuration, corresponding submerged burners (not shown) may protrude from the upper ends of the protrusions C1, C2, and C3, and corresponding cooling medium nozzles or piping L may be provided within the protrusions to cool the corresponding submerged burners.

[0048] Here, specific configurations of submerged burners F that can be used in a glass melting furnace 100 according to the present invention will be described. Parts (a) and (b) of FIG. 5 show a top view and a longitudinal cross-sectional view, respectively, of two exemplary submerged burners F. Each of these submerged burners includes a fuel passage 10 connected to a fuel supply source and an oxidizer passage 20 connected to an oxidizer supply source. The fuel passage 10 and the oxidizer passage 20 can be configured to discharge the fuel and the oxidizer, respectively, outside the submerged burner F, where they mix. For example, in the illustrated embodiment, the fuel passage 10 and the oxidizer passage 20 can extend parallel to the axis of the burner to a nozzle at the tip of the submerged burner. That is, the fuel and the oxidizer do not need to be premixed before being ejected from the nozzle. Because the submerged burners extend into the glass melt, the high temperature in the melt can quickly ignite the fuel and the oxidizer, which are mixed only when they are outside the nozzle. Furthermore, when hydrogen is used as fuel, the reaction time between the combustion of hydrogen and an oxidizer (e.g., oxygen) is very short, which also contributes to rapid combustion. Naturally, at least one of the fuel passage 10 and the oxidizer passage 20 may also be configured to cause the discharged fuel and / or oxidizer to form a swirling flow, thereby improving mixing of the fuel and / or oxidizer. For example, spiral grooves may be provided on the inner walls of the fuel passage 10 and / or the oxidizer passage 20, so that the discharged fuel and / or oxidizer form a swirling flow accordingly. The submerged burner F shown in part (b) of Figure 5 differs from the submerged burner F shown in part (a) in that a cooling jacket 30, which allows a cooling medium to circulate, is further provided around the outer periphery of the submerged burner in part (b) for the purpose of cooling the submerged burner.

[0049] Advantageously, two or more submerged burners F may be provided. When a given amount of heat needs to be provided, the greater the number of submerged burners, the lower the power output of each burner. Lower power output from each burner can result in shorter flames and more complete heat transfer to the glass liquid. Also, lower-powered submerged burners can generate fewer and smaller bubbles in the glass melt. In embodiments, two or more of the submerged burners F described above may share a cooling system and / or a system for supplying fuel and oxidizer, thereby forming a burner assembly. As shown in FIG. 6 , a burner assembly formed by, for example, three submerged burners may be connected to a common fuel pipe 210 and a common oxidizer pipe 220 to receive the supplied fuel and oxidizer, and to a common cooling medium inlet pipe 230 and a common cooling medium outlet pipe 240 to utilize the same cooling system for cooling.

[0050] Those skilled in the art will understand that the above-described embodiments are all illustrative and that those skilled in the art may make improvements to the embodiments, and that the various main elements described in the embodiments may be freely combined as long as they are not inconsistent in terms of structure or principle.

[0051] After the detailed description of the preferred embodiments of the present invention, those skilled in the art will clearly understand that various changes and modifications can be made without departing from the scope and spirit of the appended claims, and that the present invention is not limited to the embodiments described herein as examples.

Claims

1. A melting device (100) comprising a melting space in which a material can be melted, the melting space being surrounded by at least a bottom wall (120) and a side wall (130), the melting device further comprising at least one electric heater (E) and at least one submerged burner (F) disposed within the melting space for heating the material; the submerged burner (F) is disposed upstream of the electric heater (E) in a direction in which the material melt flows through the melting space and is discharged from the melting space; The melting apparatus (100) is characterized in that the at least one submerged burner (F) includes a plurality of submerged burners (F1, F2, F3) protruding from the bottom wall (120) into the material melt, and the heights to which the plurality of submerged burners protrude from the bottom wall (120) increase in order in the melt flow direction.

2. 2. The melting device (100) according to claim 1, wherein the submerged burner (F) and the electric heater (E) are configured so that a high temperature point (K) in the melting space is located downstream of the submerged burner (F) in the melt flow direction, and the melt flow direction is a direction in which the material melt flows within the melting space and is released from the melting space.

3. 2. The melting device (100) of claim 1, wherein the submerged burners (F) and the electric heaters (E) are configured such that 50% or more of the energy used to heat and melt the material is provided by the electric heaters and less than 50% is provided by the submerged burners.

4. The melting device (100) according to claim 3, characterized in that the submerged burner (F) and the electric heater (E) are configured so that 70% to 80% of the energy used to heat and melt the material is provided by the electric heater.

5. The submerged burner (F) and the electric heater (E) are configured so that less than 20% of the energy used to heat and melt the material is provided by the submerged burner. The melting device (100) according to claim 3, characterized in that

6. The melting apparatus (100) according to claim 3, further comprising a burner (R) arranged above the surface (S) of the material melt, the burner being configured to supply a portion of the energy used to heat and melt the material other than the energy supplied by the submerged burner (F) and the electric heater (E).

7. 7. The melting device (100) of claim 6, wherein the burner (R) is configured to provide 10% of the energy used to heat and melt the material.

8. 2. The melting apparatus (100) according to claim 1, wherein the submerged burner (F) is configured such that the fuel and oxidizer supplied to the submerged burner (F) are divided into a first portion that is continuously supplied and a second portion that is intermittently supplied, the flow rate of the first portion being less than the flow rate of the second portion, the flow rate ratio between the first portion and the second portion being adjustable, and / or the supply frequency and / or supply duration of the second portion being adjustable.

9. 2. The melting device (100) according to claim 1, characterized in that the submerged burner (F) uses hydrogen as fuel.

10. 2. The melting device (100) according to claim 1, wherein the bottom wall (120) includes, on the upstream side (E) of the electric heater (E), a plurality of protrusions (C1, C2, C3) protruding into the material melt, the heights of the plurality of protrusions increasing in the melt flow direction.

11. 11. The melting device (100) of claim 10, wherein the submerged burners (F) extend from the upper ends of each of the projections.

12. 12. The melting device (100) according to claim 11, characterized in that cooling medium nozzles or pipes (L) for cooling the submerged burners (F) are housed in the protrusions (C1, C2, C3).

13. 2. The melting device (100) according to claim 1, characterized in that the at least one submerged burner (F) comprises two or more submerged burners sharing a cooling system and / or a system for supplying fuel and oxidant.

14. The melting apparatus (100) of claim 1, wherein the melted material is molten glass, molten metal, molten resin, or solid waste in a molten state.

15. 2. The melting apparatus (100) according to claim 1, characterized in that the submerged burner (F) includes a fuel passage (10) and an oxidizer passage (20) configured to discharge the fuel and the oxidizer, respectively, outside the submerged burner (F) so that the fuel and the oxidizer are mixed outside the submerged burner (F).

16. 16. The melting device (100) of claim 15, wherein at least one of the fuel passage (10) and the oxidizer passage (20) is configured to form a swirling flow of the discharged fuel and / or oxidizer.

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