Melting furnace and gas burner for melting furnace

Abstract

To provide a melting furnace equipped with a gas burner which has no possibility of erosion and is easy in maintenance.SOLUTION: In one embodiment, the gas burner has a burner nozzle 40 formed of a burner cylinder and a refractory, and is used for a shaft furnace. The burner nozzle 40 has a peripheral wall part 41 defining a combustion space 44 communicating with the burner cylinder, a plug mounting part 43 penetrating the peripheral wall part 41 and communicating with the combustion space 44, a flange part 42 provided on one end side of the peripheral wall part 41, and an injection port 45 provided on the other end side of the peripheral wall part 41.SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a melting furnace, and more particularly to a melting furnace used for melting metals. [Background technology]

[0002] Melting furnaces are broadly classified into combustion furnaces, such as shaft furnaces, and electric furnaces, such as coreless furnaces. Patent Document 1 discloses a shaft furnace used to manufacture copper wire rods. The shaft furnace described in Patent Document 1 has a cylindrical furnace body and multiple gas burners arranged along the circumferential direction of the furnace body. In this shaft furnace, combustion takes place in a reducing atmosphere to produce molten metal (molten copper). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-155384 Summary of the Invention [Problem to be solved by the invention]

[0004] Each gas burner has a metal burner nozzle facing the inside of the furnace body (inside the furnace). Melted and scattered copper adheres and accumulates on the surface of the burner nozzle facing the inside of the furnace.

[0005] Copper buildup on the burner nozzle surface reduces melting efficiency. Therefore, copper buildup on the burner nozzle surface must be removed periodically or as needed. Specifically, copper buildup on the burner nozzle must be melted and removed using a propane burner.

[0006] However, when copper deposited on the surface of a metal burner nozzle is heated using a propane burner, the burner nozzle melts. The metal components that melt from the burner nozzle are mixed into the molten copper and remain in the furnace, causing a deterioration in the quality of the molten metal.

[0007] Regardless of whether copper deposits are present or not, burner nozzles must be removed from the furnace body for periodic maintenance, but metal burner nozzles often cannot be easily removed due to thermal deformation. [Means for solving the problem]

[0008] In one embodiment, the gas burner has a burner tube and a burner nozzle made of refractory material, and is used in a melting furnace for melting metal. The burner nozzle has a peripheral wall portion defining a combustion space communicating with the burner tube, a plug mounting portion penetrating the peripheral wall portion and communicating with the combustion space, a flange portion provided on one end of the peripheral wall portion, and an injection port provided on the other end of the peripheral wall portion. [Effects of the Invention]

[0009] According to the present invention, a melting furnace equipped with a gas burner that is free from the risk of melting damage and is easy to maintain can be realized. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a copper wire rod manufacturing system. [Figure 2] FIG. 1 is a front view of a shaft furnace. [Figure 3] FIG. 2 is a side view (partial cross section) of a gas burner. [Figure 4A] FIG. 2 is a front view of the burner nozzle. [Figure 4B] FIG. 2 is a cross-sectional view of a burner nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment will be described in detail below with reference to the drawings. In all drawings referred to in describing the embodiment, the same or substantially the same configurations and elements are designated by the same reference numerals. Furthermore, once a configuration or element has been described, it will not be described again.

[0012] <Manufacturing system overview> Fig. 1 is a schematic diagram of a wire rod manufacturing system 1. More specifically, the manufacturing system 1 shown in Fig. 1 is a copper wire rod manufacturing system. This manufacturing system 1 includes a melting furnace 2, a casting device 3, a rolling device 4, a winding device 5, etc.

[0013] The melting furnace 2 heats the metal or alloy that is the material for the wire rod to produce molten metal. In this embodiment, the melting furnace 2 heats copper to produce molten metal (molten copper). The melting furnace 2 is a shaft furnace equipped with multiple gas burners. Therefore, in the following description, the melting furnace 2 may be referred to as the "shaft furnace 2." In the shaft furnace 2, copper is charged and heated to a temperature above its melting point by the gas burners.

[0014] The molten metal produced in the shaft furnace 2 is supplied to the casting device 3. The casting device 3 is a belt wheel type continuous casting device. The casting device 3 cools and solidifies (coagulates) the molten metal supplied from the shaft furnace 2 to continuously produce rod-shaped (square rod-shaped) casting material C.

[0015] The cast material C produced by the casting device 3 is supplied (fed) to the rolling device 4. The rolling device 4 is a roller-type continuous rolling device. The rolling device 4 hot-rolls the fed cast material C to continuously produce a bar-shaped (round bar-shaped) rolled material R. For example, the rolling device 4 continuously produces a round bar-shaped rolled material R having an outer diameter of 8.0 mm to 23.0 mm.

[0016] The rolled material R sent out from the rolling device 4 is subjected to predetermined treatments and processes. For example, the rolled material R is subjected to surface purification processes such as acid washing and reduction washing. The rolled material R that has been subjected to the predetermined treatments and processes is taken up by a winding device 5 as a copper wire rod D. The winding device 5 winds up the taken-up copper wire rod D in a spiral shape. The winding device 5 is also called a "coiler."

[0017] A preheating furnace may be provided upstream of the shaft furnace 2. A holding furnace may be provided between the shaft furnace 2 and the casting device 3.

[0018] <Casting equipment> The casting device 3 includes a tundish 11, a pouring nozzle 12, a die wheel 13, a belt 14, guide rollers 15, a tension wheel 16, and the like.

[0019] The tundish 11 stores the molten metal supplied from the shaft furnace 2. The pouring nozzle 12 is connected to the tundish 11 and discharges the molten metal stored in the tundish 11 around the die wheel 13. A flow rate control pin is provided at the tip (discharge port) of the pouring nozzle 12 to adjust the supply amount (discharge amount) of the molten metal.

[0020] The die wheel 13 has a cylindrical or disc shape. A groove is provided on the outer periphery of the die wheel 13 over the entire circumference. The belt 14 is an endless belt. The belt 14 is made of stainless steel (SUS / Steel Special Use Stainless), and rotates while contacting a portion of the outer periphery of the rotating die wheel 13.

[0021] When the belt 14 comes into contact with the outer peripheral surface of the mold wheel 13, a casting space is formed around the mold wheel 13. More specifically, the belt 14 comes into contact with part of the outer peripheral surface of the mold wheel 13 and rotates while blocking part of the circumferential direction of the groove. As a result, the belt 14 and the part of the groove blocked by the belt 14 form a casting space around the mold wheel 13. From another perspective, a mold (casting die) is formed between the mold wheel 13 and the belt 14.

[0022] The belt 14 is wound around a plurality of guide rollers 15 and a tension wheel 16. The belt 14 is given tension mainly by the tension wheel 16, and rotates while being pressed against a part of the outer circumferential surface of the die wheel 13.

[0023] The die wheel 13 and the belt 14 are cooled by cooling water or the like. Therefore, the molten metal supplied to the casting space formed by them is cooled and solidified (coagulated). As a result, a casting material C having substantially the same cross-sectional shape as the casting space is continuously produced. In this embodiment, a casting material C having a rectangular or approximately rectangular cross-section is continuously produced.

[0024] In another embodiment, an application unit is provided to apply a release agent to the surface of the die wheel 13 or the surface of the belt 14. From another perspective, in another embodiment, a release agent is applied to the inner surface of the die (casting mold). The release agent is, for example, soot-like graphite (soot) generated by incomplete combustion of acetylene gas.

[0025] <Shaft furnace> 2 is a front view of the shaft furnace 2. The shaft furnace 2 has a cylindrical furnace body 21 and a plurality of gas burners 22. More specifically, the shaft furnace 2 has seven lower-stage gas burners 22a, eight middle-stage gas burners 22b, and four upper-stage gas burners 22c.

[0026] The gas burners 22 on each stage are arranged at the same height and at predetermined intervals along the circumferential direction of the furnace body 21. From another perspective, the gas burners 22 on each stage are provided around the furnace body 21 so as to surround the furnace body 21.

[0027] Each gas burner 22 burns fuel (air mixture) and injects a flame toward the inside of the furnace body 21. In this embodiment, air mixed with liquefied natural gas (LNG) is supplied to the gas burners 22 as fuel.

[0028] A fuel supply passage 23 is provided near each stage of the gas burners 22. More specifically, a fuel supply passage 23a for supplying fuel to the lower stage gas burners 22a is provided above the lower stage gas burners 22a. The fuel supply passage 23a is formed by a metal pipe that extends in an annular shape so as to surround the furnace body 21.

[0029] Similarly, a fuel supply passage 23b for supplying fuel to the middle-stage gas burner 22b is provided above the middle-stage gas burner 22b, and a fuel supply passage 23c for supplying fuel to the upper-stage gas burner 22c is provided above the upper-stage gas burner 22c. Like the fuel supply passage 23a, the fuel supply passages 23b and 23c are formed by metal pipes extending in an annular shape so as to surround the furnace body 21.

[0030] <Gas burner> Fig. 3 is a side view of the gas burner 22. However, Fig. 3 shows a cross section of a portion (burner nozzle 40) of the gas burner 22. The 19 gas burners 22 of the shaft furnace 2 have the same or substantially the same structure. Specifically, the gas burner 22 has a coaxial burner cylinder 30, a burner nozzle 40, and an observation window 50.

[0031] The burner tube 30 is cylindrical. The burner nozzle 40 is provided at one axial end of the burner tube 30, and the sight glass 50 is provided at the other axial end of the burner tube 30. Here, the one axial end of the burner tube 30 where the burner nozzle 40 is provided is defined as the "tip end," and the other axial end of the burner tube 30 where the sight glass 50 is provided is defined as the "rear end" or "base end."

[0032] The above definition applies not only to the burner tube 30 but also to the gas burner 22 including the burner tube 30. However, the above definition is merely provided for the convenience of explanation.

[0033] The burner tube 30 is provided with a connecting pipe 31 that extends in a direction intersecting the axial direction of the burner tube 30. The connecting pipe 31 is connected to a joint 24 (FIG. 2) that protrudes from the fuel supply passage 23. As a result, the burner tube 30 is connected to the fuel supply passage 23 via the joint 24 and the connecting pipe 31. In other words, the gas burner 22 is connected to the fuel supply passage 23, and fuel can be supplied to the gas burner 22.

[0034] The sight glass 50 is composed of a lens barrel 51 that protrudes from the rear end face of the burner tube 30 and heat-resistant glass (not shown) that is fitted into the lens barrel 51. The inside of the burner tube 30 and the inside of the burner nozzle 40 can be seen through the sight glass 50. From another perspective, the combustion state of the gas burner 22 can be confirmed through the sight glass 50, and the state of copper adhesion to the burner nozzle 40 can also be confirmed.

[0035] <Burner nozzle> Fig. 4A is a front view of burner nozzle 40, and Fig. 4B is a cross-sectional view of burner nozzle 40. More specifically, the cross-section shown in Fig. 4B is taken along line AA in Fig. 4A. Burner nozzle 40 is made of refractory material and has a peripheral wall portion 41, a flange portion 42, and a plug mounting portion 43.

[0036] Although the manufacturing method of the burner nozzle 40 is not particularly limited, the burner nozzle 40 of this embodiment is a molded product manufactured using a mold. More specifically, the burner nozzle 40 of this embodiment is a molded product obtained by pouring a castable refractory material into a mold and forming it into a predetermined shape.

[0037] Pressure molding or compression molding is another example of a method for manufacturing the burner nozzle 40. For example, the burner nozzle 40 may be manufactured by pressing a powdered castable refractory material filled in a mold.

[0038] Examples of refractories used as materials for the burner nozzle 40 include silicon carbide, silicon oxide, and silicon nitride.

[0039] The peripheral wall portion 41 is the main portion of the burner nozzle 40 and defines a combustion space 44 that communicates with the burner tube 30. The combustion space 44 is a generally tapered space. In other words, the combustion space 44 is a generally conical space.

[0040] More specifically, the combustion space 44 is composed of a large-diameter region 44a, an intermediate region 44b, and a small-diameter region 44c. The large-diameter region 44a, the intermediate region 44b, and the small-diameter region 44c are aligned in this order from the rear end to the tip end of the burner nozzle 40.

[0041] The large diameter region 44a and the small diameter region 44c are each a cylindrical space having a constant inner diameter, while the intermediate region 44b is a tapered (conical) space whose inner diameter gradually decreases.

[0042] The flange portion 42 has an annular shape and protrudes radially outward from the rear end of the peripheral wall portion 41. The plug mounting portion 43 is a through-hole that obliquely penetrates the peripheral wall portion 41 and communicates with the inside and outside of the combustion space 44. More specifically, one end of the plug mounting portion 43 communicates with the small diameter region 44c.

[0043] The burner nozzle 40 is fixed to the tip of the burner tube 30 and is integrated with the burner tube 30. More specifically, as shown in Fig. 3, the burner nozzle 40 is fixed to the burner tube 30 by clamping a flange portion 42 provided at the rear end between clamps 32, 32.

[0044] From another perspective, the tip of the burner tube 30 is fixed to the rear end of the burner nozzle 40, which is fixed to the peripheral wall or water-cooled jacket of the furnace body 21. Then, a combustion space 44 is formed between the burner tube 30 and the furnace body 21, communicating with both of them.

[0045] Although not shown, an ignition plug (spark plug) is inserted into the plug mounting portion 43. When the ignition plug generates a spark, combustion of fuel begins in the combustion space 44. Furthermore, the flame generated by the combustion of the fuel is injected into the furnace from the tip (injection port 45) of the burner nozzle 40. As a result, copper is heated and melted in the furnace. The molten copper (molten metal) is taken out from the bottom of the furnace body 21 shown in FIG. 2 and supplied to the tundish 11 shown in FIG. 1.

[0046] 4B, the overall length L of burner nozzle 40 is 148 mm, the outer diameter D1 of peripheral wall portion 41 is 103 mm, and the outer diameter D2 of flange portion 42 is 144 mm. Furthermore, the inner diameter d1 of small diameter region 44c (injection port 45) of burner nozzle 40 is 48 mm, and the inner diameter d2 of large diameter region 44a is 90 mm.

[0047] Furthermore, the inner diameter d3 of the plug mounting portion 43 is 15 mm, and the inclination angle θ is 35°. However, the above dimensions are all examples, and the dimensions of each portion of the burner nozzle 40 can be changed as appropriate.

[0048] <Copper removal> When the shaft furnace 2 is operated, copper that melts and scatters adheres to and accumulates on the burner nozzle 40. The copper that has accumulated on the burner nozzle 40 is melted and removed. As described above, the burner nozzle 40 of this embodiment is made of a refractory material. Therefore, even if the copper that has accumulated on the burner nozzle 40 is heated using a propane burner, no melting damage occurs to the burner nozzle 40. As a result, the contamination of the molten metal with metal materials is prevented, and the quality of the molten metal is improved and stabilized.

[0049] In addition, the burner nozzle 40, which is made of a refractory material, is unlikely to be deformed by heat. Furthermore, the burner nozzle 40, which is made of a refractory material, can be easily broken and removed. Therefore, the time required for replacement and maintenance of the burner nozzle 40 and the gas burner 22 including the burner nozzle 40 is significantly reduced.

[0050] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the number and arrangement of the gas burners 22 provided in the shaft furnace 2 can be changed as appropriate. The shaft furnace 2 can also be used to melt metals other than copper. [Explanation of symbols]

[0051] 1. Manufacturing system 2...Melting furnace (shaft furnace) 3...Casting equipment 4...Rolling equipment 5... Winding device 11...Tundish 12...Pouring nozzle 13...Mold wheel 14...Belt 15...Guide roller 16...Tension wheel 21... Furnace body 22...Gas burner 22a...Lower gas burner 22b...Middle gas burner 22c...Upper gas burner 23,23a,23b,23c…Fuel supply path 24...Joint 30...Burner tube 31...Connecting pipe 32...Flange 40...Burner nozzle 41...Peripheral wall part 42...Flange 43...Plug mounting part 44...Combustion space 44a...Large diameter area 44b…middle area 44c…Small diameter area 45...Injection port 50...Sightseeing window 51...Telescope tube

Claims

1. A gas burner used in a melting furnace for melting metal, a burner cylinder and a burner nozzle formed of a refractory material, The burner nozzle is a peripheral wall portion defining a combustion space communicating with the burner cylinder; a plug mounting portion that penetrates the peripheral wall portion and communicates with the combustion space; a flange portion provided on one end side of the peripheral wall portion; a gas burner having an injection port provided on the other end side of the peripheral wall portion.

2. the combustion space includes a large diameter region, a small diameter region, and an intermediate region located between the large diameter region and the small diameter region, the larger diameter region and the smaller diameter region each have a constant inner diameter; 2. The gas burner according to claim 1, wherein the inner diameter of said intermediate region gradually decreases from the side of said large diameter region toward the side of said small diameter region.

3. 3. The gas burner according to claim 2, wherein the plug mounting portion communicates with the small diameter region of the combustion space.

4. 4. The gas burner according to claim 3, wherein the plug mounting portion obliquely penetrates the peripheral wall portion and communicates with the small diameter region.

5. A melting furnace for melting metal, A cylindrical furnace body; a plurality of gas burners provided around the furnace body; Each of the gas burners has a burner cylinder and a burner nozzle made of refractory material, The burner nozzle of a melting furnace has a peripheral wall portion that defines a combustion space that communicates with the burner cylinder, a plug mounting portion that penetrates the peripheral wall portion and communicates with the combustion space, a flange portion provided on one end side of the peripheral wall portion, and an injection port provided on the other end side of the peripheral wall portion.

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