Tower type aluminum melting furnace

Abstract

To efficiently melt aluminum while suppressing the generation of nitrogen oxides without generating carbon monoxide.SOLUTION: In the tower type aluminum melting furnace 1, aluminum A charged into a tower-shaped combustion chamber 10 from an upper opening part 12 is melted by flame F of a burner 20 provided to face a hearth 11 of the combustion chamber 10, and hydrogen is used as fuel of the burner 20. A hearth 11 of the combustion chamber 10 is inclined in the direction crossing the injection direction of the flame F from the burner 20, and a molten metal chamber 30 in which the aluminum A melted in the combustion chamber 10 flows down is provided adjacent to the combustion chamber 10 and below the combustion chamber 10. The length L1 in the injecting direction of the flames F of the burner 20 is set so that the tip part of the flames F exceeds the hearth 11 when the hearth 11 of the chamber 10 is not present.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tower-type aluminum melting furnace for melting aluminum (including aluminum alloys), which is a non-ferrous metal. [Background technology]

[0002] BACKGROUND ART Conventionally, tower-type aluminum melting furnaces have been widely used as equipment for melting aluminum (aluminum alloys) for the purpose of casting die-cast products and the like (see, for example, Patent Document 1). This tower-type aluminum melting furnace burns petroleum-derived fossil fuels or natural gas in a burner, and uses the resulting heat to melt aluminum.

[0003] The tower-type aluminum melting furnace described in Patent Document 1 uses fossil fuel as fuel, and therefore generates carbon dioxide, which poses an environmental problem that must be solved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-272171 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the melting furnace described in Patent Document 1 still has problems to be solved. That is, even in this melting furnace using hydrocarbon as fuel, carbon monoxide is generated unless the hydrocarbon is completely burned in the combustion chamber of the melting furnace.

[0006] Therefore, as shown in FIG. 3, when hydrocarbons are used as fuel for burners 20 provided opposite the hearth 11 of the combustion chamber 10 in a tower-type aluminum melting furnace 1, the length L2 in the radial direction of the flame F sprayed from the burner 20 must be set so that its tip just reaches the hearth 11 of the combustion chamber 10. If the flame F is set to exceed the hearth 11, the flame F will collide with the hearth 11, making it difficult for the fuel to be completely burned in the combustion chamber 10, and as a result, the carbon monoxide mentioned above is likely to be generated.

[0007] However, in the tower-type aluminum melting furnace 1, if the tip of the flame F is set to just reach the hearth 11, problems remain in the melting efficiency. In the tower-type aluminum melting furnace 1, aluminum A is sequentially introduced into the combustion chamber 10 through the upper opening 12, and the aluminum A that reaches the part of the melting chamber 10 facing the burner 20 is melted by the flame F. Therefore, the introduced aluminum A is also present above the part of the melting chamber 10 facing the burner 20. Therefore, in order to improve melting efficiency, it is desirable to sufficiently preheat this upper aluminum A with the flame F of the burner 20. However, if the tip of the flame F is set just to reach the hearth 11, the flame F will not reach the aluminum A above it, so sufficient preheating will not be possible, and the melting efficiency will not be improved.

[0008] Conversely, if the flame F of the burner 20 is set so as not to reach the hearth 11, the flame F will not reach all of the aluminum present in the area opposite the burner 20, and therefore the aluminum will not be sufficiently melted within the specified time, making it impossible to improve melting efficiency. Therefore, in order to sufficiently melt the aluminum within the specified time, it is necessary to increase the combustion temperature of the flame F by, for example, increasing the amount of hydrocarbons to be combusted. However, it is known that increasing the amount of hydrocarbons burned in a tower-type aluminum melting furnace increases the amount of carbon monoxide and nitrogen oxides produced, which poses environmental problems.

[0009] Therefore, an object of the present invention is to provide a tower-type aluminum melting furnace and a combustion method for such a tower-type aluminum melting furnace that can efficiently melt aluminum while suppressing the generation of nitrogen oxides and without generating carbon monoxide. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a tower-type aluminum melting furnace (1) that melts aluminum (A) introduced into a tower-shaped combustion chamber (10) through an upper opening (12) with a flame (F) from a burner (20) that is provided opposite a hearth (11) of the combustion chamber (10), and The burner (20) is characterized in that the fuel is hydrogen.

[0011] The present invention is also characterized in that the hearth (11) of the combustion chamber (10) is inclined in a direction intersecting the spray direction of the flame (F) from the burner (20), and a molten metal chamber (30) is provided adjacent to and below the combustion chamber (10), through which the molten aluminum (A) in the combustion chamber (10) flows down.

[0012] Furthermore, the present invention provides a combustion method for a tower-type aluminum melting furnace (1), which comprises: melting aluminum (A) introduced into a tower-shaped combustion chamber (10) from an upper opening (12) with a flame (F) from a burner (20) disposed opposite a hearth (11) of the combustion chamber (10), using hydrogen as fuel for the burner (20); tilting the hearth (11) of the combustion chamber (10) in a direction intersecting the injection direction of the flame (F) from the burner (20); and providing a molten metal chamber (30) adjacent to the combustion chamber (10) and positioned lower than the combustion chamber (10), through which the molten aluminum (A) flows down. The length (L1) of the flame (F) of the burner (20) in the injection direction is set to such an extent that the tip of the flame (F) would extend beyond the hearth (11) of the combustion chamber (10) if there were no hearth (11).

[0013] The present invention is also characterized in that the length (L1) of the flame (F) of the burner (20) in the injection direction is set to 1.5 to 4 times the distance from the burner (20) to the hearth (11) of the combustion chamber (10).

[0014] Here, the symbols in parentheses indicate corresponding elements or items shown in the drawings and in the detailed description to be described later. [Effects of the Invention]

[0015] According to the tower-type aluminum melting furnace of the present invention, aluminum is fed into a tower-shaped combustion chamber from an upper opening, and is melted by the flame of a burner located opposite the hearth of the combustion chamber.Since hydrogen is used as fuel for the burner, this characteristic makes it possible to melt aluminum without generating carbon compounds such as carbon monoxide and carbon dioxide.

[0016] Furthermore, according to the present invention, the hearth of the combustion chamber is inclined in a direction intersecting the direction of flame injection from the burner, and a molten metal chamber into which molten aluminum in the combustion chamber flows is provided adjacent to and below the combustion chamber. This allows the molten aluminum to smoothly flow down from the inclined hearth into the molten metal chamber under its own weight without generating carbon compounds. As a result, the dissolution efficiency can be improved.

[0017] Furthermore, according to the combustion method for a tower-type aluminum melting furnace of the present invention, in the tower-type aluminum melting furnace having the above-described configuration, the length of the burner flame in the injection direction is set to such an extent that the tip of the flame would extend beyond the hearth if there were no hearth in the combustion chamber. This allows the aluminum to be surrounded by the flame and melted efficiently without generating carbon compounds.

[0018] In other words, because hydrogen is used as the burner fuel, its properties prevent the generation of carbon compounds. Also, by setting the length of the burner flame in the direction of injection so that the tip of the flame would extend beyond the hearth of the combustion chamber if there were no hearth, sufficient heat can be provided to all of the aluminum present in the hearth facing the burner, allowing for efficient melting.

[0019] Furthermore, with the above-described configuration, the flame ejected from the burner hits the hearth and disperses, reaching the aluminum present above the point on the hearth facing the burner, thereby enabling the aluminum present there to be sufficiently preheated. This reduces the time required to melt aluminum and increases the melting efficiency. Furthermore, since aluminum is present in the combustion area of ​​the burner, the temperature of the combustion area can be lowered, which in turn can reduce the generation of nitrogen oxides.

[0020] Furthermore, in the present invention, the length of the burner flame in the injection direction is set to 1.5 to 4 times the distance from the burner to the hearth of the combustion chamber, which is defined as 1. Therefore, sufficient heat can be provided to all of the aluminum present in the area of ​​the hearth facing the burner, making it possible to melt it efficiently. At the same time, the flame reflected and dispersed by the hearth can sufficiently preheat the aluminum present above the area of ​​the hearth facing the burner, thereby shortening the melting time and improving melting efficiency.

[0021] The above-mentioned patent documents do not describe at all a tower-type aluminum melting furnace in which the burner burns hydrogen as fuel, eliminating the generation of carbon compounds, as in the present invention.Furthermore, the above-mentioned patent documents do not describe at all a combustion method for a tower-type aluminum melting furnace in which the length of the burner flame in the injection direction is set so that the tip of the flame extends beyond the hearth of the combustion chamber if there were no hearth. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a side view showing a tower-type aluminum melting furnace and a combustion method using the same according to an embodiment of the present invention. [Figure 2] 1 is a side view showing a tower-type aluminum melting furnace and a combustion method using the same according to an embodiment of the present invention (showing a state in which a dispersed flame is generated). FIG. [Figure 3] FIG. 1 is a side view showing an example of the use of carbonitride in a tower-type aluminum melting furnace according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0023] Referring to FIG. 1, a tower-type aluminum melting furnace 1 according to an embodiment of the present invention will be described. The tower-type aluminum melting furnace 1 according to this embodiment melts lump (including granular) aluminum A, which is fed into a tower-shaped combustion chamber 10 from an upper opening 12, with a flame F of a burner 20 provided opposite a hearth 11 of the combustion chamber 10, and hydrogen is used as fuel for the burner 20. The aluminum A also includes aluminum alloys.

[0024] Additionally, the hearth 11 of the combustion chamber 10 is inclined in a direction intersecting the direction in which the flame F is sprayed from the burner 20. The angle of inclination of the hearth 11 is not limited, but is set to an extent that allows the aluminum A introduced from the upper opening 12 to remain on the hearth 11 and allows the molten aluminum A to smoothly flow down under its own weight. Furthermore, a molten metal chamber 30 is provided adjacent to and below the combustion chamber 10. Aluminum (molten metal) A1 melted in the hearth 11 of the combustion chamber 10 flows down under its own weight into this molten metal chamber 30, where it is maintained in a molten state. Furthermore, an open / close lid 13 is provided at the upper opening 12 of the combustion chamber 10, and by closing this open / close lid 13, it is possible to prevent the temperature of the combustion chamber 10 from dropping.

[0025] The tower-type aluminum melting furnace 1 according to the above embodiment uses hydrogen as fuel for the burner 20, and is therefore able to melt aluminum A without generating carbon compounds. Furthermore, the hearth 11 of the combustion chamber 10 is inclined, and a molten metal chamber 30 is provided through which the molten aluminum A flows under its own weight, eliminating the need for a means for transporting the molten aluminum A to the molten metal chamber 30. As a result, efficient melting can be achieved.

[0026] Next, with reference to Figure 2, a combustion method for a tower-type aluminum melting furnace according to an embodiment of the present invention will be described. The tower-type aluminum melting furnace 1 used in this combustion method includes a tower-shaped combustion chamber 10, and chunks of aluminum A fed into the upper opening 12 are melted with flames F from burners 20 disposed opposite the hearth 11 of the combustion chamber 10. The burners 20 burn hydrogen as fuel. The combustion chamber 10 includes a hearth 11 that is inclined in a direction intersecting the direction in which the flames F are ejected from the burners 20. A molten metal chamber 30, through which the molten aluminum A flows, is provided adjacent to and below the combustion chamber 10.

[0027] A feature of this combustion method is that the length L1 of the flame F of the burner 20 in the injection direction is set so that the tip of the flame F would extend beyond the hearth 11 of the combustion chamber 10 if there were no hearth 11. If the distance from the burner 20 to the hearth 11 of the combustion chamber 10 is taken as 1, the length L1 of the flame F of the burner 20 in the injection direction is preferably 1.5 to 4 times this distance.

[0028] In the combustion method for a tower-type aluminum melting furnace according to this embodiment, the burner 20 uses hydrogen as fuel, so that aluminum A can be melted without generating carbon compounds such as carbon monoxide and carbon dioxide, unlike when hydrocarbons are used.

[0029] Furthermore, the length L1 of the flame F of the burner 20 in the injection direction is set so that the tip of the flame F would extend beyond the hearth 11 of the combustion chamber 10 if there were no hearth 11, thereby improving the melting efficiency of the aluminum A.

[0030] That is, with this setting, the flame F that hits the hearth 11 is reflected by the hearth 11 and dispersed in all directions (the flame F1 dispersed in all directions is referred to here as the "dispersed flame F1"). Of these, the dispersed flame F1 that reaches above the hearth 11 impinges on the aluminum A present above the portion of the hearth 11 facing the burner 20, and heats (preheats) the aluminum A.

[0031] The preheated aluminum A is directly hit by the flame F of the burner 20 below it, and as the melted aluminum A flows down into the molten metal chamber 30, it slides down the inclined hearth 11 to the location opposite the burner 20. The aluminum A that has moved to this location is directly hit by the flame F of the burner 20 and melts, but because it has been sufficiently preheated by the dispersed flame F1 prior to this, it melts in a short time and flows down into the molten metal chamber 30. This increases the melting efficiency.

[0032] Furthermore, since aluminum A is present in the combustion region of burner 20, the temperature of the combustion region can be lowered, and therefore the generation of nitrogen oxides can be suppressed.

[0033] The length L1 of the flame F of the burner 20 in the injection direction is preferably 1.5 to 4 times the distance from the burner 20 to the hearth 11 of the combustion chamber 10, where L1 is the distance from the burner 20 to the hearth 11 of the combustion chamber 10. If the length L1 is less than 1.5 times, the flame F reflected by the hearth 11 will not be sufficiently dispersed in all directions, and a large dispersed flame F1 will not be formed, making it difficult to sufficiently preheat the aluminum A. Furthermore, since less aluminum A is enveloped in the flame, the melting efficiency will not be improved.

[0034] Furthermore, if the length L1 of the flame F in the injection direction exceeds 4 times, the aluminum A present in the area facing the burner 20 will be heated and melted not by the outer flame of the flame F but by the inner flame, which has a lower temperature, so the flame temperature will drop too much and melting efficiency will not be achieved. Therefore, it is preferable to set the length L1 of the flame F in the injection direction in the range of 1.5 to 4 times. These were estimated by the present inventors from experimental results.

[0035] The length L1 of the flame F in the injection direction can also be determined by the capacity of the burner 20. In this case, the distance between the burner 20 and the hearth 11 can be determined first, and then a burner 20 with a capacity corresponding to that can be selected. Conversely, the burner 20 can be selected first, and the distance between the burner 20 and the hearth 11 can be set according to the capacity. This also applies when multiple burners 20 are provided. [Explanation of symbols]

[0036] 1. Tower-type aluminum melting furnace 10 Combustion chamber 11 hearth 12 Upper opening 13 Opening and closing lid 20 Burner 30 Melt Chamber A. Aluminum (lump) A1 Molten aluminum (molten metal) F flame F1 dispersed flame L1 Length in the injection direction (present invention) L2 Length in the injection direction (conventional technology)

Claims

1. A tower-type non-ferrous metal melting furnace in which aluminum is fed into a tower-shaped combustion chamber from an upper opening and melted by flames from burners provided opposite the hearth of the combustion chamber, A tower-type aluminum melting furnace characterized in that the burner uses hydrogen as fuel.

2. 2. The tower-type aluminum melting furnace according to claim 1, wherein the hearth of the combustion chamber is inclined in a direction intersecting the direction of flame injection from the burner, and a molten metal chamber, into which molten aluminum flows, is provided adjacent to and below the combustion chamber.

3. A combustion method for a tower-type aluminum melting furnace, in which aluminum is introduced into a tower-shaped combustion chamber from an upper opening and melted by flames from burners provided opposite the hearth of the combustion chamber, the burners are fueled with hydrogen, the hearth of the combustion chamber is inclined in a direction intersecting the direction of flame injection from the burners, and a molten aluminum chamber is provided adjacent to and below the combustion chamber, through which molten aluminum flows down, A combustion method for a tower-type aluminum melting furnace, characterized in that the length of the burner's flame in the injection direction is set so that the tip of the flame would extend beyond the hearth of the combustion chamber if there were no hearth.

4. The combustion method for a tower-type aluminum melting furnace according to claim 3, characterized in that the length of the burner's flame injection direction is set to 1.5 to 4 times the distance from the burner to the hearth of the combustion chamber, where 1 is the distance from the burner to the hearth of the combustion chamber.

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