Blowing pipe and blowing structure

Abstract

This blowing pipe is inserted into a blast furnace from the shaft or the belly of the furnace, and is provided with a gas circulation cylinder having a blowing opening that is at a tip section thereof and opens into the furnace. When a peripheral wall at the tip section of the gas circulation cylinder is viewed in a cross section perpendicular to a pipe axis direction of the blowing pipe, if an inner diameter dimension along a long axis direction of the peripheral wall is w(mm) and an inner diameter dimension along a short axis direction of the peripheral wall is h(mm), w / h is more than 1.0.

Description

Inlet pipe and inlet structure

[0001] This invention relates to a blowing pipe and a blowing structure. This application claims priority based on Japanese Patent Application No. 2025-048862, filed in Japan on March 24, 2025, the contents of which are incorporated herein by reference.

[0002] In typical blast furnace operation, iron-based raw materials and coke (hereinafter, iron-based raw materials and coke may be referred to as furnace interior materials) are charged into the furnace alternately and in layers from the top, while hot air is blown into the furnace from the tuyeres at the bottom along with pulverized coal. The CO gas generated by this blowing rises inside the furnace, heating and reducing the iron-based raw materials. The reduced iron-based raw materials melt and are further reduced by the coke as they drip down the furnace, and are extracted as pig iron from the taphole and used in the next steelmaking process. In typical blast furnace operation, carbon materials such as coke and pulverized coal are used, so a large amount of carbon dioxide (CO) is produced. ２ ) is generated. On the other hand, in recent years, there has been a call to prevent global warming, and CO2, one of the greenhouse gases, is being targeted. ２ A reduction in CO2 emissions is required. ２ New blast furnace operating methods are being considered to reduce emissions.

[0003] For example, Patent Document 1 discloses a method of operating a blast furnace in which modified top exhaust gas is injected into the furnace from a tuyeres or an injection port (shaft injection port) located in the middle section of the furnace. Patent Document 2 discloses CO and H ２ A blast furnace is disclosed that includes a device configured to introduce a high-temperature gas containing CO, H into the blast furnace shaft, i.e., from above the tuyere level. Patent Document 3 discloses a device that includes CO, H at the corners of staves arranged in the furnace wall. ２ and N ２ A blast furnace is disclosed that has a hole for inserting a reducing gas injection device containing a reducing gas.

[0004] Japanese Patent Publication No. 2015-129325, Japanese Patent Publication No. 2023-543051, International Publication No. 2022-058773

[0005] When reducing gas is injected into the furnace from the blast furnace shaft, there is a concern that a region with a low density of furnace contents may form near the furnace wall, hindering the stable descent (loading stability) of the furnace contents.

[0006] Therefore, the purpose of this disclosure is to provide a blowing pipe and blowing structure that can improve load lowering stability.

[0007] The gist of this disclosure is as follows: [1] A blown-in pipe inserted into a blast furnace from the shaft or belly section, comprising a gas flow tube having a blown-in opening at its tip that opens into the furnace, wherein when the peripheral wall at the tip of the gas flow tube is viewed in a cross section perpendicular to the pipe axis direction of the blown-in pipe, the inner diameter dimension of the peripheral wall along the long axis direction is w (mm) and the inner diameter dimension of the peripheral wall along the short axis direction is h (mm), and w / h is greater than 1.0. [2] The blown-in pipe according to [1] above, wherein w / h is 20.0 or less. [3] The blown-in pipe according to [1] or [2] above, wherein the cross-sectional shape of the peripheral wall is rectangular or elliptical. [4] The blown-in pipe according to any one of [1] to [3] above, wherein a refrigerant flow path is provided in the peripheral wall. [5] The blown-in pipe according to any one of [1] to [4] above, wherein an insulating material is provided on the inner surface of the peripheral wall of the gas flow tube. [6] The blowing pipe according to any one of [1] to [5] above, wherein the gas flow tube has a flow straightening member inside. [7] The blowing pipe according to any one of [1] to [6] above, wherein when the blowing pipe is viewed in a cross section along the axis of the pipe, the blowing opening is oriented diagonally downward. [8] A blowing structure comprising the blowing pipe according to any one of [1] to [7] above, and a group of staves composed of a plurality of staves arranged on the furnace wall of the shaft portion or the belly portion of the blast furnace, wherein a blowing pipe insertion port is formed in the furnace wall of the shaft portion or the belly portion through which the blowing pipe is inserted. [9] The blowing structure according to [8] above, wherein the group of staves comprises an upper group of staves and a lower group of staves arranged below it.

[10] The blowing structure according to [9] above, wherein the blowing pipe insertion port is formed by a through hole formed in the refractory material between the upper group of staves and the lower group of staves.

[11] The blowing structure according to either [9] or

[10] , wherein the blowing pipe insertion port is formed below the boundary line between adjacent staves on the left and right in the upper stave group.

[12] The blowing structure according to any one of [9] to

[11] , wherein the boundary line between adjacent staves on the left and right in the upper stave group and the boundary line between adjacent staves on the left and right in the lower stave group are located at different positions in the circumferential direction of the furnace.

[13] The blowing structure according to any one of [9] to

[12] above, wherein the blowing pipe insertion port is formed by a notch formed in at least one of the lower end of the stave of the upper stave group and the upper end of the stave of the lower stave group.

[14] The blowing structure according to [8] or [9] above, wherein the blowing pipe insertion port is formed by a through hole formed in the stave.

[15] The blowing structure according to

[14] above, wherein the stave has a plate portion and a projection portion that protrudes from the plate portion toward the core, and the blowing pipe insertion port is formed in the plate portion below the projection portion.

[16] The blowing structure according to any one of [8] to

[15] above, wherein an abrasion-resistant layer is provided at the tip portion of the gas flow tube.

[17] The blowing structure according to any one of [8] to

[16] above, wherein, when viewed in a cross section perpendicular to the core axis, the central axis of the blowing pipe, including the blowing opening, intersects with respect to the furnace radial direction.

[18] The blowing structure according to

[17] above, wherein, when viewed in the cross section, the angle of intersection of the central axis of the blowing pipe with respect to the furnace radial direction is greater than -60 degrees and less than 60 degrees.

[19] The blowing structure according to

[17] or

[18] above, wherein, when viewed in a cross section along the pipe axis direction, the blowing opening faces diagonally downward.

[20] The blowing structure according to any one of [8] to

[19] above, wherein two or more blowing pipe insertion ports are formed in the furnace wall in the shaft portion or the belly portion, spaced apart in the vertical direction, and two or more blowing pipes communicating with a single gas supply pipe are inserted through the two or more blowing pipe insertion ports.

[0008] According to this disclosure, a blowing pipe and blowing structure capable of improving load lowering stability are provided.

[0009] Figure 1 is a schematic longitudinal cross-sectional view showing a blast furnace using the blown-in pipe according to this embodiment. Figure 2A is a schematic transverse cross-sectional view showing the section II-II in Figure 1. Figure 2B is a transverse cross-sectional view at a position including the blown-in pipe insertion port in a modified case where the blown-in pipe insertion port is formed in the center of the stave. Figure 3 is a longitudinal cross-sectional view showing a blown-in structure including the blown-in pipe according to this embodiment, and is an enlarged view of section III in Figure 1. Figure 4 is a transverse cross-sectional view showing the blown-in pipe according to this embodiment. Figure 5 is a schematic cross-sectional view showing the section V-V in Figure 4. Figure 6A is a transverse cross-sectional view showing an example of a blown-in pipe having a flow straightening member. Figure 6B is a transverse cross-sectional view showing another example of a blown-in pipe having a flow straightening member. Figure 7 is a perspective cross-sectional view showing the positional relationship between the stave group and the blown-in pipe insertion port in the blown-in structure according to this embodiment. Figure 8A is a perspective cross-sectional view showing a first modified example of the positional relationship between the stave group and the blown-in pipe insertion port. Figure 8B is a perspective cross-sectional view showing a second modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8C is a perspective cross-sectional view showing a third modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8D is a perspective cross-sectional view showing a fourth modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8E is a perspective cross-sectional view showing a fifth modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8F is a perspective cross-sectional view showing a sixth modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8G is a perspective cross-sectional view showing a seventh modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 8H is a perspective cross-sectional view showing an eighth modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 9 is a perspective cross-sectional view showing a part of a stave with a projection. Figure 10A is a schematic cross-sectional view showing a modified example of the inlet structure according to this embodiment. Figure 10B is a cross-sectional view at a position including the inlet pipe insertion port in a modified case where the inlet pipe insertion port is formed in the center of the stave. Figure 11 is a longitudinal cross-sectional view schematically showing a modified example of an inlet structure using the inlet pipe according to this embodiment. Figure 12 is an enlarged view showing section XII of Figure 11. Figure 13 is a longitudinal cross-sectional view schematically showing a configuration in which two gas flow tubes are connected via two branch pipes.

[0010] Hereinafter, the blowing pipe 10 according to the first embodiment of the present invention will be described with reference to the drawings.

[0011] [Definition of Direction of Blast Furnace 1] In this disclosure, the direction in which the core axis A extends (vertical direction), that is, the direction along the core axis A, is called the up-down direction. Of the up-down direction, the direction from the top 1a of the blast furnace 1 toward the bottom 1b is called the down side, and the direction from the bottom 1b toward the top 1a is called the up side. The direction perpendicular to the core axis A is called the radial direction. Of the radial direction, the direction approaching the core axis A is called the inner radial direction, and the direction moving away from the core axis A is called the outer radial direction. Note that the inner radial direction may sometimes simply be called the core direction. The direction that circles around the core axis A is called the circumferential direction.

[0012] [Definition of the direction of the inlet pipe 10] In this disclosure, the direction in which the central axis O of the inlet pipe 10 extends, that is, the direction along the central axis O, is called the pipe axis direction. Of the pipe axis direction, the direction from the branch pipe 20 (described later) toward the inlet pipe 10 is called the tip side or simply the tip side in the pipe axis direction, and the direction from the inlet pipe 10 toward the branch pipe 20 is called the base end side or simply the base end side in the pipe axis direction. The direction perpendicular to the central axis O is called the pipe diameter direction. Of the pipe diameter direction, the direction approaching the central axis O is called the inside of the pipe diameter direction, and the direction moving away from the central axis O is called the outside of the pipe diameter direction. The direction that circles around the central axis O is called the pipe circumferential direction.

[0013] The blast furnace 1 to which the blowing pipe 10 according to this embodiment is applied is a facility that reduces iron ore and extracts molten pig iron. As shown in Figure 1, the core axis A, which is the central axis of the blast furnace 1, extends in the vertical direction. The blast furnace 1 has a bottomed cylindrical shape centered on the core axis A. Although not shown in Figure 1, iron-based raw materials and coke are charged into the blast furnace 1 alternately and in layers from the top 1a.

[0014] [Components of Blast Furnace 1] Blast furnace 1 comprises a shaft section 2, a belly section 3, a Bosch section 4, and a hearth section 5. The shaft section 2, belly section 3, Bosch section 4, and hearth section 5 are arranged in this order from the top 1a of the furnace to the bottom 1b of the furnace.

[0015] The shaft section 2 has a tapered cylindrical shape that widens towards the bottom. The diameter of the shaft section 2 increases towards the bottom. The belly section 3 has a cylindrical shape that extends along the core axis A. The belly section 3 has a straight body shape, and its diameter is constant at each position in the vertical direction.

[0016] The Bosch section 4 has a tapered cylindrical shape that decreases in diameter towards the bottom. The diameter of the Bosch section 4 decreases towards the bottom. The hearth section 5 is located at the lower end of the blast furnace 1. The hearth section 5 is approximately cylindrical in shape. In the illustrated example, the inner diameter of the hearth section 5 decreases in stages towards the bottom. The hearth section 5 is provided with a taphole (not shown). The pig iron produced in the blast furnace 1 is removed from the furnace through the taphole.

[0017] As shown in Figure 1, the blast furnace 1 includes a tuyere 6 provided on the furnace wall of the hearth section 5, and a blowpipe insertion port 7 located above the tuyere 6 and provided on the furnace wall of the shaft section 2. The blowpipe insertion port 7 may also be provided on the furnace wall of the belly section 3.

[0018] Multiple tuyeres 6 are provided on the furnace wall of the hearth section 5, spaced apart from each other in the circumferential direction of the furnace. The hot air and enriched oxygen gas blown into the blast furnace 1 from the tuyeres 6 react with the auxiliary reducing agent blown in from the tuyeres 6 along with the hot air, and with the coke in the furnace to generate high-temperature CO gas. Recirculating gas, natural gas, ammonia, etc., which reuse the exhaust gas from the top of the furnace, can also be blown into the furnace. Examples of auxiliary reducing agents include pulverized coal, waste plastics, heavy oil, and propane gas. Note that auxiliary reducing agents may not always be blown into the furnace.

[0019] As shown in Figure 2, the blowing pipe insertion port 7 penetrates the furnace wall of the shaft section 2. Multiple blowing pipe insertion ports 7 are provided spaced apart from each other in the circumferential direction of the furnace. In the shaft section 2 of the blast furnace 1, the furnace wall has, in order from the outermost layer toward the inside in the radial direction of the furnace, a steel shell 1c and a stave 1d, with refractory material 1e placed between them. The steel shell 1c is made of, for example, steel plate. The stave 1d is a plate-shaped water-cooled metal fitting with a refrigerant water channel provided to protect the furnace wall from heat load. The material of the stave 1d is not particularly limited, but from the viewpoint of workability, thermal conductivity, etc., it is preferably copper or a copper alloy. Multiple staves 1d are provided arranged in the vertical and circumferential directions so as to cover the furnace wall from the inside in the radial direction of the furnace. The refractory material 1e includes both press-fit material (unshaped refractory material) and stamp material (refractory material that can absorb compressive deformation). Furthermore, the fire-resistant material 1e has a portion that is provided as a joint to seal the space between staves 1d that are arranged adjacent to each other in the vertical or circumferential direction of the furnace.

[0020] Figure 2A is a cross-sectional view at a position including the blowing pipe insertion port 7 when the blowing pipe insertion port 7 is formed in the refractory material 1e (Figure 7, described later). In Figure 2A, the iron shell 1c and the refractory material 1e are present between adjacent blowing pipe insertion ports 7. Figure 2B is a cross-sectional view at a position including the blowing pipe insertion port 7 in a modified case where the blowing pipe insertion port 7 is formed in the center of the stave 1d (Figure 8G, described later). In Figure 2B, the iron shell 1c, the refractory material 1e, and the stave 1d are present between adjacent blowing pipe insertion ports 7. Figures 2A and 2B show an example in which eight blowing pipe insertion ports 7 are provided at equal pitches in the circumferential direction of the furnace. However, the number of blowing pipe insertion ports 7 is not limited to eight; it may be seven or fewer, or nine or more. Also, they do not have to be at equal pitches in the circumferential direction of the furnace. An inlet pipe 10 is inserted through the inlet pipe insertion port 7 to inject reducing gas from the shaft section 2 of the blast furnace 1 into the furnace. In other words, the blast furnace 1 is equipped with an inlet pipe 10 attached to the furnace wall of the shaft section 2. Note that in Figures 1, 2A, and 2B, the inlet pipe 10 is shown in a simplified and schematic manner.

[0021] A reducing gas is blown from the blowing pipe 10. Blowing the reducing gas promotes the reduction of iron-based raw materials, which can reduce the coke ratio (the mass of coke required for producing 1 ton of hot metal) and the auxiliary reducing agent ratio (the mass of auxiliary reducing agent required for producing 1 ton of hot metal, which becomes the pulverized coal ratio when the auxiliary reducing agent is pulverized coal), and can reduce the carbon consumption in the blast furnace 1.

[0022] Among the reducing gases, the hydrogen-based reducing gas refers to a gas that contains H in an element composition ratio of 30 mol% or more and exists as a gas under standard conditions (0°C, 1 atm). Hydrogen-based reducing gas is, for example, H ２ gas, unsaturated hydrocarbon gases (C ２ H ４ , C ２ H ２ , C ３ H ６ , etc.), saturated hydrocarbon gases (CH ４ , C ２ H ６ , etc.), NH ３ gas, coke oven gas, city gas, natural gas, etc., and mixed gases thereof. Hydrogen-based reducing gas is particularly preferably H ２ gas, unsaturated hydrocarbon gases (C ２ H ４ , C ２ H ２ , C ３ H ６ , etc.). H ２ gas does not contain carbon, and no thermal decomposition reaction occurs at the tip of the blowing pipe 10, so it is preferable from the perspective of reducing the specific carbon consumption. In addition, since H ２ gas has low viscosity and density, it is also preferable from the perspective of air permeability in the blast furnace.

[0023] Furthermore, while the hydrogen-based reducing gas may be injected into the blast furnace at room temperature, it is preferable that it be injected in a heated state for heat supply to the blast furnace 1. The heating temperature of the hydrogen-based reducing gas is, for example, 500°C or higher, 1000°C or higher, or 1200°C or higher. Unsaturated hydrocarbon gases are preferred because they contain double or triple bonds in their gas molecules, resulting in a relatively large heat of combustion per 1 mol of oxygen, and they also serve as a heat source at the end of the injection pipe 10. It is even more preferable that the elemental composition ratio of H in the hydrogen-based reducing gas is 50 mol% or higher. Furthermore, the hydrogen-based reducing gas may contain other gases (for example, N) (without impairing the effects of this embodiment). ２ A mixed gas with (or other gas) is also acceptable.

[0024] Furthermore, when reducing gas is injected into the furnace from the shaft section 2 of the blast furnace, it is preferable to set the gas flow rate of the reducing gas injected from the injection pipe 10 so that cavities (combustion spaces) called raceways are not formed near the furnace wall. Specifically, in order to suppress the formation of raceways, the gas flow rate of the reducing gas injected from the injection pipe 10 is set to, for example, 160 m / s or less so that the formation of raceways can be stably suppressed. The gas flow rate of the reducing gas injected from the injection pipe 10 into the shaft section 2 may be less than 200 m / s.

[0025] The configuration of the blowing pipe 10 will be described in detail below with reference to Figures 3 to 6B.

[0026] As shown in Figure 3, the blowing pipe 10 is cylindrical with a central axis O. In this embodiment, the central axis O of the blowing pipe 10 extends along the furnace diameter direction (see Figures 1 and 2). In this embodiment, the tip of the blowing pipe 10 (the inner end in the furnace diameter direction) protrudes by a protrusion amount P1 from the inner surface of the furnace wall of the shaft portion 2 (the plate surface of the stave 1d facing in the furnace diameter direction). The tip of the blowing pipe 10 may be positioned so as not to protrude from the inner surface of the furnace wall of the shaft portion 2. The tip of the blowing pipe 10 may be positioned so as to be flush with the inner surface of the furnace wall of the shaft portion 2 (protrusion amount P1 = 0 mm).

[0027] [Components of the inlet pipe 10] The inlet pipe 10 comprises a gas flow tube 12, an insulating material 13, and a flange 14.

[0028] The gas flow cylinder 12 is a member that allows reducing gas to flow inside, and has a cylindrical shape centered on the central axis O. The gas flow cylinder 12 extends along the central axis O in the tube axial direction.

[0029] As shown in FIG. 4, the gas flow cylinder 12 includes a distal end portion 12A, an intermediate portion 12B, and a proximal end portion 12C from the distal side toward the proximal side. The distal end portion 12A is a portion having a flat cross-section, and the proximal end portion 12C is a portion having a circular cross-section. The intermediate portion 12B is a portion whose cross-section transitions from the flat shape to the circular shape from the distal side to the proximal side.

[0030] The distal end of the distal end portion 12A of the gas flow cylinder 12 is exposed inside the furnace of the shaft portion 2. The distal end portion 12A of the gas flow cylinder 12 is provided with a blowing opening 12a for blowing reducing gas into the furnace of the shaft portion 2.

[0031] As shown in FIGS. 4 and 5, the distal end portion 12A of the gas flow cylinder 12 has a peripheral wall 121 configured by an upper wall 121a, a lower wall 121b, and a pair of side walls 121c.

[0032] In the present disclosure, in a cross-section perpendicular to the tube axial direction (FIG. 5), the direction along the major axis of the distal end portion 12A of the gas flow cylinder 12 is referred to as the major axis direction, and the direction along the minor axis of the distal end portion 12A of the gas flow cylinder 12 is referred to as the minor axis direction. As shown in FIG. 5, when w (mm) is the inner diameter dimension along the major axis direction of the peripheral wall 121 at the distal end portion 12A of the gas flow cylinder 12, and h (mm) is the inner diameter dimension along the minor axis direction of the peripheral wall 121 at the distal end portion 12A of the gas flow cylinder 12, w / h is greater than 1.0. That is, when the peripheral wall 121 at the distal end portion 12A of the gas flow cylinder 12 is viewed in a cross-section perpendicular to the tube axial direction of the blowing tube 10, w (mm) is the inner diameter dimension along the major axis direction of the peripheral wall 121, and h (mm) is the inner diameter dimension along the minor axis direction of the peripheral wall 121, w / h is greater than 1.0.

[0033] The inlet pipe 10 of this disclosure is inserted into the shaft section 2 of the blast furnace 1 with its long axis aligned with the horizontal direction. Therefore, if the w / h is greater than 1.0, the following effects can be obtained when the inlet pipe 10 is inserted into the blast furnace 1: (a) Since the injection energy is dispersed in the direction of the long axis, it is possible to suppress the formation of a region with a low density of furnace fill material near the inlet. This improves the stability of the load descent. Furthermore, when such an inlet pipe 10 is inserted into the blast furnace 1 with its long axis aligned with the horizontal direction, the following effects can be obtained: (b) The shaft section is above the molten zone inside the furnace. Therefore, fine particles of furnace fill material can easily enter the inlet of the reducing gas injection device formed in the shaft section, which can lead to blockage of the inlet. However, when the inlet pipe 10 is inserted into the blast furnace 1 with its long axis aligned with the horizontal direction, furnace fill material descending vertically is less likely to enter the horizontally extending inlet. Therefore, the effect of suppressing blockage of the inlet can be obtained. (c) Staves (stave coolers) are provided in the shaft section to protect the furnace wall, but when reducing gas is blown in from the shaft section, it is necessary to leave space between the staves or to process the staves as shown in Patent Document 3. In that case, a decrease in the cooling capacity of the staves (hereinafter referred to as stave cooling capacity) is unavoidable. Since the staves 1d can be inserted into the furnace wall without processing them or without performing any major processing, the effect of suppressing the decrease in stave cooling capacity can be obtained.

[0034] When using a blowing device with a circular opening cross-section (w / h of 1.0), it is possible to improve load-down stability by setting a slower gas flow rate for the reducing gas blown in from the blowing pipe 10. However, when the opening cross-section is circular, it becomes necessary to increase the opening diameter or the number of openings, which is undesirable from the viewpoint of suppressing blockage of the blowing port and suppressing a decrease in stave cooling capacity. On the other hand, in the blowing pipe 10 according to this embodiment, since w / h is greater than 1.0, even without setting the gas flow rate of the reducing gas excessively slow, the blowing energy is dispersed horizontally, and the formation of a region with a low density of furnace interior material near the blowing port can be suppressed. Combined with the effects of suppressing blockage of the blowing port and suppressing a decrease in stave cooling capacity mentioned above, the productivity of pig iron can be improved.

[0035] The w / h is preferably 1.2 or higher, and more preferably 1.5 or higher. The w / h may be 2.0 or higher or 3.0 or higher. There is no particular upper limit for the w / h, but if it exceeds 20.0, it becomes difficult to blow uniformly in the longitudinal direction. Also, since it affects the strength of the furnace wall, it is preferable that the w / h is 20.0 or lower. The w / h may be 15.0 or lower or 10.0 or lower.

[0036] In this embodiment, the upper wall 121a and the lower wall 121b are arranged to face each other, and the pair of side walls 121c are also arranged to face each other, so that the peripheral wall 121 has a rectangular cross-sectional shape. However, in a cross-section perpendicular to the pipe axis, when the inner diameter dimension along the long axis of the tip portion 12A of the gas flow tube 12 is w (mm) and the inner diameter dimension along the short axis of the tip portion 12A of the gas flow tube 12 is h (mm), the cross-sectional shape is not limited to a rectangle, but may be a polygon or an ellipse as long as the w / h is greater than 1.0.

[0037] The tip of the inlet pipe 10 is preferably configured to protrude from the inner surface of the furnace wall of the shaft section 2 in order to prevent fine powder and other materials from the furnace contents descending inside the furnace from entering the inlet opening (see the protrusion amount P1 in Figure 3). Furthermore, by having the tip of the inlet pipe 10 protrude from the inner surface of the furnace wall, the decrease in load-down stability due to the concentration of reducing gas near the furnace wall is suppressed, and effects such as suppression of blockage of the inlet opening and easier injection of reducing gas can be expected. In addition, by having the tip of the inlet pipe 10 protrude from the inner surface of the furnace wall, the flow of reducing gas along the furnace wall is suppressed, and while maintaining load-down stability, it is expected that reducing gas can be supplied from the middle to the periphery of the furnace, thereby improving the reduction efficiency.

[0038] A wear-resistant layer may be provided on the protruding portion. The wear-resistant layer is, for example, an alloy (Cr-Ni alloy, Fe-Cr alloy, Al-Cu alloy) or ceramic, and has a Vickers hardness of, for example, 180 HV to 800 HV. The wear-resistant layer is formed by, for example, build-up welding, casting, bonding, thermal spraying, diffusion bonding, or dipping.

[0039] Furthermore, as shown in Figure 3, when the blowing pipe 10 is viewed in a vertical cross-section (a longitudinal cross-section along the central axis O) including the blowing opening 12a, it is preferable that the blowing opening 12a is oriented diagonally downward. In the longitudinal cross-sectional view shown in Figure 3, in this embodiment, the blowing opening 12a extends toward the base end in the direction of the pipe axis as it goes downward. In this case, it becomes difficult for the furnace contents that descend inside the furnace to enter the blowing opening 12a. This helps to suppress blockage of the blowing opening.

[0040] As shown in Figure 3, a refrigerant passage 122 through which a refrigerant such as water flows is provided in the peripheral wall 121 at the tip end of the gas flow tube 12. In this embodiment, the refrigerant passage 122 is provided inside the peripheral wall 121 of the gas flow tube 12. The refrigerant passage 122 extends in the circumferential direction of the pipe around the central axis O inside the peripheral wall 121. The gas flow tube 12 also has pipe connection ports 122a and 122b provided on its outer surface. The pipe connection ports 122a and 122b are in communication with the refrigerant passage 122. The arrangement of the pipe connection ports 122a and 122b is not particularly limited. One of the pipe connection ports 122a and 122b is an inlet for supplying refrigerant to the refrigerant passage 122, and the other is an outlet for discharging refrigerant from the refrigerant passage 122. Multiple inlets and outlets may be provided. The refrigerant flow path 122 may be provided as appropriate depending on the gas injection temperature and the heat resistance temperature of the gas flow tube 12. For example, it may be provided from the tip portion 12A to the intermediate portion 12B and the base portion 12C. The refrigerant flow path 122 may not be provided at all.

[0041] The gas flow tube 12 is made of, for example, a heat-resistant alloy. The heat resistance temperature of the gas flow tube 12 is set to be above the gas temperature of the reducing gas flowing inside the gas flow tube 12. The heat resistance temperature of the gas flow tube 12 is, for example, 800 to 1200°C. If a refrigerant flow path 122 is not provided, the heat resistance temperature of the gas flow tube 12 is preferably 900°C or higher, more preferably 1000°C or higher. The material of the gas flow tube 12 is, for example, heat-resistant stainless steel, Ni-based alloy, etc. If a refrigerant flow path 122 is provided, the heat resistance temperature of the gas flow tube 12 may be lower than the gas temperature of the reducing gas flowing inside, and for example, copper, copper alloy, etc. with high thermal conductivity can be used.

[0042] The insulating material 13 is provided on the inner circumferential surface of the gas flow tube 12. The gas flow tube 12 will be exposed to high temperatures, especially at its tip. For this reason, the insulating material 13 is provided inside the blowing opening 12a. More specifically, the insulating material 13 is cylindrical with a central axis O as its center and extends in the direction of the pipe axis. The insulating material 13 is positioned adjacent to the gas flow tube 12 on the inside of the peripheral wall 121 of the gas flow tube 12 in the direction of the pipe diameter. The insulating material 13 covers the inner circumferential surface of the peripheral wall 121 of the gas flow tube 12 from the inside in the direction of the pipe diameter. The insulating material 13 may be provided as appropriate depending on the gas blowing temperature and the heat resistance temperature of the gas flow tube 12, and for example, it may be provided only in the tip portion 12A. The insulating material 13 may not be provided at all. The insulating material 13 is mainly Al ２ O ３ Monomorphic refractories containing, mainly Al ２ O ３ and SiO ２ Examples include amorphous refractories containing such materials.

[0043] A flange 14 is provided on the outer circumferential surface of the base end portion 12C of the gas flow tube 12 in the direction of the pipe axis. The flange 14 is an annular plate shape centered on the central axis O. As shown in Figures 2 and 3, the flange 14 is connected to the flange 24 formed on the tip side of the branch pipe 20 by fastening with bolts and nuts (not shown) opposite to the flange 24. The base end portion 12C of the gas flow tube 12 is cylindrical in shape centered on the central axis O. The base end portion 12C extends in the direction of the pipe axis along the central axis O. The diameter of the base end portion 12C is approximately the same as the diameter of the tip of the branch pipe 20 and the diameter of the inner circumference of the flange 24.

[0044] In this embodiment, a branch pipe 20 communicating with an annular pipe 30 is connected to the base end of the blowing pipe 10. The branch pipe 20 is connected to the blowing pipe 10 from the base end in the direction of the pipe axis and supplies reducing gas to the blowing pipe 10. As shown in Figure 3, the branch pipe 20 has an outer casing 22, an insulating material 23, and a flange 24.

[0045] The outer casing 22 is cylindrical with a central axis O and extends in the direction of the pipe axis. The heat insulating material 23 is provided on the outer casing 22 and the inner circumferential surface in the direction of the pipe diameter. The flange 24 is provided on the outer circumference of the tip side of the outer casing 22 and is an annular plate shape with a central axis O.

[0046] As shown in Figure 1, the multiple branch pipes 20 branch off from the annular pipe 30 downwards and inwards in the radial direction of the furnace. The annular pipe 30 supplies reducing gas to the inlet pipe 10 through the branch pipes 20. The annular pipe 30 is an annular shape centered on the furnace core axis A and is located on the outside of the shaft section 2 in the radial direction of the furnace. In Figure 1, the annular pipe 30 is located above the inlet pipe insertion port 7, but the annular pipe 30 may also be located below the inlet pipe insertion port 7. In this case, the branch pipes 20 branch off from the annular pipe 30 upwards and inwards in the radial direction of the furnace.

[0047] [Effects of this embodiment] In the blowing pipe 10 of this embodiment described above, since the w / h is greater than 1.0, it is possible to improve load lowering stability, suppress blockage of the blowing port, and suppress the decrease in stave cooling capacity, thereby increasing the production efficiency of pig iron.

[0048] [Other Configurations Included in the Invention] The present invention is not limited to the embodiments described above, and modifications to the configuration are possible without departing from the spirit of the invention, as described below, for example. In the illustration of modified examples, the same reference numerals are used for the same components as in the embodiments described above, and the differences will be mainly described below.

[0049] As shown in Figures 6A and 6B, the gas flow tube 12 of the inlet pipe 10 may have a flow straightening member 16 inside. In the inlet pipe 10 of this embodiment, since a flat inlet opening is used, the importance of uniform injection in the longitudinal direction increases. If the gas injection is uneven in the longitudinal direction, the reaction rate with the furnace interior contents, the gas injection rate into the furnace, and the gas flow rate will be uneven, which may adversely affect the load lowering stability. In the modified example shown in Figure 6A, the upper and lower ends of the columnar flow straightening bar 16a with a rhombic cross-section are joined to the lower surface of the upper wall 121a and the upper surface of the lower wall 121b on the central axis O of the intermediate portion 12B of the gas flow tube 12. In the modified example shown in Figure 6B, the upper and lower ends of the plate-shaped flow straightening plate 16b are joined to the lower surface of the upper wall 121a and the upper surface of the lower wall 121b on the central axis O of the tip portion 12A of the gas flow tube 12.

[0050] These modifications allow for uniform gas injection in the longitudinal direction even when the injection opening has a flattened shape, thereby improving load lowering stability. Multiple or different types of flow straightening members 16 may be installed. Specifically, multiple flow straightening bars 16a and flow straightening plates 16b may be installed at different locations in the injection pipe 10, or a flow straightening plate 16b may be installed downstream of a flow straightening bar 16a. When installing multiple flow straightening bars 16a and flow straightening plates 16b, it is preferable to install them at symmetrical positions with respect to the central axis O.

[0051] Hereinafter, the blowing structure 50 according to the second embodiment of the present invention will be described with reference to the drawings.

[0052] [Injection Structure 50] The injection structure 50 according to this embodiment is an injection structure that injects reducing gas into the furnace from the shaft portion 2 of the blast furnace, and comprises the injection pipe 10 described above and a plurality of staves 1d arranged on the furnace wall of the shaft portion 2.

[0053] As shown in Figure 7, a plurality of staves 1d are arranged in the vertical and circumferential directions to cover the furnace wall of the blast furnace 1 from the inside in the radial direction, thereby constituting a stave group 1dG. The stave group 1dG has an upper stave group 1dGU, which is composed of a plurality of staves 1d arranged in the circumferential direction at a specific height position, and a lower stave group 1dGL, which is located below the upper stave group 1dGU and is composed of a plurality of staves 1d arranged in the circumferential direction. An inlet pipe insertion port 7 is formed in the furnace wall of the shaft section 2. In the inlet structure 50 according to this embodiment, an inlet pipe insertion port 7 is formed between the upper stave group 1dGU and the lower stave group 1dGL, which are composed of a plurality of staves 1d, and penetrates the furnace wall of the shaft section 2.

[0054] The inlet pipe insertion port 7 is preferably sized to conform to the shape of the tip portion 12A of the gas flow tube 12 of the inlet pipe 10. That is, when the first dimension along the horizontal direction is w' (mm) and the second dimension along the vertical direction is h' (mm), it is preferable that w' / h' is greater than 1.0 and 20.0 or less. It is more preferable that w' / h' is greater than 1.2, and even more preferable that it is greater than 1.5.

[0055] As shown in Figure 7, in the blowing structure 50 according to this embodiment, the blowing pipe insertion port 7 is a through-hole formed in the refractory material 1e (amorphous refractory material or stamped material) between the upper stave group 1dGU and the lower stave group 1dGL. With this configuration, the blowing pipe insertion port 7 can be provided in the furnace wall by effectively utilizing the refractory material 1e, which contributes less to the cooling effect compared to the staves 1d, without processing the staves 1d. Therefore, a decrease in the stave cooling capacity can be suppressed.

[0056] The following describes a preferred configuration for the air inlet based on Figures 8A to 8F.

[0057] As shown in the modified example in Figure 8A, the blowing pipe insertion port 7 may be formed below the boundary line between adjacent staves 1d on the left and right in the upper stave group 1dGU. Of the refractory material 1e extending in the circumferential direction of the furnace, the portion below the boundary line between adjacent staves 1d on the left and right has the smallest cooling effect from the staves. Therefore, forming the blowing pipe insertion port 7 in this portion can further suppress the decrease in stave cooling capacity.

[0058] Furthermore, as shown in the modified example in Figure 8B, if the positions of the boundary lines between adjacent staves 1d in the upper stave group 1dGU and the boundary lines between adjacent staves 1d in the lower stave group 1dGL are different in the circumferential direction of the furnace, an inlet pipe insertion port 7 may be formed in the refractory material 1e. In this case, the cooling effect by the staves 1d in the vicinity of the refractory material 1e extending in the circumferential direction of the furnace can be made uniform.

[0059] Furthermore, as shown in the modified examples in Figures 8C, 8D, 8E, and 8F, the blown-in pipe insertion port 7 may be formed by a notch 1d1 formed in at least one of the lower end of the stave 1d of the upper stave group 1dGU and the upper end of the stave 1d of the lower stave group 1dGL.

[0060] In the modified example shown in Figure 8C, the inlet pipe insertion port 7 is formed by two notches 1d1 formed at the lower end of the center of the furnace circumferential direction of the stave 1d of the upper stave group 1dGU and at the upper end of the center of the furnace circumferential direction of the stave 1d of the lower stave group 1dGL.

[0061] In the modified example shown in Figure 8D, the inlet pipe insertion port 7 is formed by a single notch 1d1 formed at the lower end of the center of the stave 1d in the furnace circumferential direction of the upper stave group 1dGU. Although not shown in the figure, the inlet pipe insertion port 7 may also be formed by a single notch 1d1 formed at the upper end of the center of the stave 1d in the furnace circumferential direction of the lower stave group 1dGL.

[0062] In the modified example shown in Figure 8E, the inlet pipe insertion port 7 is formed by four notches 1d1 formed at the lower ends of the furnace circumferential ends of the staves 1d adjacent to the upper stave group 1dGU in the furnace circumferential direction, and at the upper ends of the furnace circumferential ends of the staves 1d adjacent to the lower stave group 1dGL in the furnace circumferential direction.

[0063] In the modified example shown in Figure 8F, the inlet pipe insertion port 7 is formed by three notches 1d1 formed at the lower ends of the furnace circumferential ends of adjacent staves 1d in the upper stave group 1dGU and at the upper end of the furnace circumferential center of the staves 1d in the lower stave group 1dGL.

[0064] According to the modifications shown in Figures 8C, 8D, 8E, and 8F, the blown-in pipe insertion port 7 is formed by a notch 1d1 formed in at least one of the lower end of the stave 1d of the upper stave group 1dGU and the upper end of the stave 1d of the lower stave group 1dGL. This makes it possible to provide the blown-in pipe insertion port 7 in the furnace wall without performing significant processing on the stave 1d and while suppressing the vertical width of the refractory material 1e between the upper stave group 1dGU and the lower stave group 1dGL. As a result, a decrease in the stave cooling capacity can be suppressed.

[0065] In the modified example shown in Figure 8G, the inlet pipe insertion port 7 is formed by a through hole 1d2 formed in the stave 1d. The through hole 1d2 penetrates the stave 1d in the direction of its plate thickness (i.e., the furnace radial direction). According to this embodiment, the staves 1d arranged vertically can be placed close together, thereby improving cooling performance. As shown in the modified example shown in Figure 8H, the inlet pipe insertion port 7 may be formed by a notch 1d1 formed at the furnace circumferential ends of a pair of staves 1d adjacent to each other in the furnace circumferential direction. Note that in Figure 8H, the inlet pipe insertion port 7 is located between adjacent staves 1d in the furnace circumferential direction of the upper stave group 1dGU, but the configuration is not limited to this. The inlet pipe insertion port 7 may also be located between adjacent staves 1d in the furnace circumferential direction of the lower stave group 1dGL.

[0066] Furthermore, as shown in the modified example in Figure 9, the stave 1d may have a plate portion 1d3 and a projection 1d4 that protrudes inward (towards the core) in the radial direction of the furnace from the plate portion 1d3.

[0067] The pair of plate surfaces of plate portion 1d3 face both sides (inward and outward) in the radial direction of the furnace. A refrigerant water channel (not shown) is also provided inside plate portion 1d3. Although not specifically shown, the refrigerant water channel is connected to a water inlet that supplies cooling water from the outside of shaft portion 2 in the radial direction of the furnace, and a drain outlet that discharges cooling water from the refrigerant water channel to the outside of shaft portion 2 in the radial direction of the furnace.

[0068] The protruding portion 1d4 extends in the direction of the furnace core from the plate surface of the plate portion 1d3 facing inward in the furnace radial direction and extends in the furnace circumferential direction. The protruding portion 1d4 is rib-shaped. The amount of protrusion P2 of the protruding portion 1d4 inward in the furnace radial direction from the inner surface of the plate portion 1d3 is preferably greater than or equal to the amount of protrusion P1 of the blowing pipe 10 inward in the furnace radial direction from the inner surface of the plate portion 1d3. In addition, multiple protruding portions 1d4 are provided spaced apart from each other in the vertical direction.

[0069] According to this embodiment, a self-lining effect can be obtained by having the descending furnace interior filler enter between the upper and lower protrusions 1d4.

[0070] In the modified example shown in Figure 9, the inlet pipe insertion port 7 is formed by a notch 1d1 located below the protruding portion 1d4. In the example shown in Figure 9, the notch 1d1 is located below the protruding portion 1d4 and adjacent to it, but the notch 1d1 only needs to be formed within the plate portion 1d3 above the midline between the upper and lower protruding portions 1d4. The inlet pipe insertion port 7 may also be formed by a through hole 1d2 that penetrates the stave 1d in the thickness direction of the plate.

[0071] With this configuration, the descending furnace contents interfere with the protrusion 1d4, so a region with a low density of furnace contents is formed near the opening. This helps to suppress blockage of the injection port. In other words, since the protrusion 1d4 of the stave 1d is positioned to cover the injection opening 12a of the injection pipe 10 from directly above, it becomes more difficult for furnace contents to enter the injection opening 12a. Therefore, blockage of the injection port can be suppressed more reliably.

[0072] Furthermore, in this embodiment, the amount of protrusion P2 of the projection 1d4 protruding inward in the radial direction of the furnace from the inner surface of the plate portion 1d3 is set to be greater than or equal to the amount of protrusion P1 of the blowing pipe 10 protruding inward in the radial direction of the furnace from the inner surface of the plate portion 1d3. Therefore, the above effect can be enhanced more stably.

[0073] [Effects of this embodiment] In the blowing structure 50 according to the second embodiment described above, since the blowing pipe 10 having a w / h of more than 1.0 as described in the first embodiment is inserted into the blowing pipe insertion port 7 in the stave group 1dG to perform blowing, it is possible to improve load lowering stability, suppress blockage of the blowing port, and suppress a decrease in stave cooling capacity, thereby increasing the production efficiency of pig iron.

[0074] [Other Configurations Included in the Invention] The present invention is not limited to the second embodiment described above, and the configuration can be modified, for example, as described below, without departing from the spirit of the invention. In the illustration of modified examples, the same reference numerals are used for the same components as in the second embodiment described above, and the differences will be mainly described below.

[0075] Figure 10A is a schematic cross-sectional view showing a modified example of the blast furnace 1 described in the above embodiment, specifically a cross-sectional view of the shaft portion 2. Note that in Figure 10A, the shape of the blowing pipe 10 is simplified (schematically) in its representation.

[0076] In this modified example, as shown in Figure 10A, when viewed in a cross-section perpendicular to the core axis A, the central axis O of the injection tube 10, including the injection opening 12a, intersects with the radial direction D. Specifically, the central axes O of each of the multiple injection tubes 10 extend toward one side of the circumferential direction of the furnace (in the illustrated example, a counterclockwise direction centered on the core axis A) as they move inward in the radial direction D.

[0077] In this case, as the reducing gas moves inward in the radial direction D from the injection opening 12a of the injection pipe 10, it is injected into the furnace toward one side in the circumferential direction. By injecting the reducing gas obliquely to the radial direction D, it becomes possible to distribute the reducing gas throughout the entire furnace in both the radial and circumferential directions. Furthermore, even if a raceway is unintentionally formed in the furnace from the injection opening 12a, the raceway is prevented from extending too far toward the core, thus preventing it from hindering the loading of the furnace contents. Therefore, loading stability is improved.

[0078] Furthermore, the angle α at which the central axis O of the inlet pipe 10 intersects the radial direction D of the furnace, as viewed in the cross-section shown in Figure 10A, is set to be greater than -60 degrees and less than 60 degrees. When the above-mentioned angle α is greater than -60 degrees and less than 60 degrees, the above-mentioned effects can be enhanced more stably. Also, when the above-mentioned angle α is less than or equal to -15 degrees or greater than or equal to 15 degrees, the reaction between the reducing gas and the furnace interior filler can be stably promoted, and productivity can be further increased.

[0079] Figure 10B is a cross-sectional view at a position including the inlet pipe insertion port 7, in a modified case where the inlet pipe insertion port 7 is formed in the center of the stave 1d. As shown in Figure 10B, even when the inlet pipe insertion port 7 is formed in the center of the stave 1d, the central axis O can intersect with the furnace radial direction D.

[0080] Figure 11 is a schematic longitudinal cross-sectional view showing a modified example of the blast furnace 1 described in the above-mentioned embodiment. Note that in Figure 11, the shape of the inlet pipe 10 is simplified (schematically) in its representation. Figure 12 is a longitudinal cross-sectional view showing a modified example of the inlet pipe 10 of the above-mentioned embodiment, and is an enlarged view of section XII in Figure 11.

[0081] In this modified configuration, as shown in Figures 11 and 12, when the blowing pipe 10 is viewed in a vertical cross-section (longitudinal section) including the blowing opening 12a, the blowing opening 12a is angled downwards. Specifically, the central axis O of the blowing pipe 10 extends downwards as it approaches the tip side in the axial direction of the pipe (inside the furnace radial direction D). This causes the blowing opening 12a to angle downwards. In this modified configuration as well, it is possible to prevent furnace contents from entering the blowing opening 12a. Therefore, blockage of the blowing opening can be suppressed. The modified configuration shown in Figure 10 described above and the modified configurations shown in Figures 11 and 12 may be combined as appropriate.

[0082] Furthermore, in the modified example shown in Figure 12, the injection opening 12a may be in the shape of an injection opening 12aa, indicated by the dashed line. In the vertical cross-sectional view shown in Figure 12, the injection opening 12aa (12a) extends in a direction perpendicular to the central axis O. Even with such an injection opening 12aa, because it faces diagonally downward, it is possible to prevent furnace interior material from entering the injection opening 12aa.

[0083] Furthermore, in the embodiments and modifications described above, the tip of the injection pipe 10 was described as protruding from the inner surface of the furnace wall of the shaft portion 2 toward the furnace core, but the invention is not limited to this. That is, the tip of the injection pipe 10 does not have to protrude from the inner surface of the furnace wall of the shaft portion 2. In this case, for example, as shown by the dashed line in Figure 12, the injection opening 12ab (12a) may be flush with the inner surface of the furnace wall of the shaft portion 2 (the amount of protrusion from the inner surface of the furnace wall is 0 mm).

[0084] Furthermore, in the above-described embodiment, as shown in Figure 1, an example was given in which one inlet pipe 10 is connected from the annular pipe 30 via one branch pipe 20 at the same position in the circumferential direction of the furnace, but the configuration is not limited to this. As shown in Figure 13, two inlet pipe insertion openings 7 spaced apart in the vertical direction are formed in the furnace wall of the shaft section 2, and two inlet pipes 10 that communicate with a single gas supply pipe (annular pipe 30 in the example shown in Figure 13) via branch pipes 20 may be inserted into the two inlet pipe insertion openings 7. The "two inlet pipe insertion openings spaced apart in the vertical direction" may be provided at the same position in the circumferential or radial direction, or they may be provided at different positions in the circumferential or radial direction. Furthermore, in the above-described embodiment and the above-described modification, an example was given in which the inlet pipe 10 is provided in the furnace wall of the shaft section 2, but the inlet pipe 10 may also be provided in the furnace wall of the belly section 3. It is preferable that the inlet pipe 10 is provided in the lower part of the shaft section 2 or in the upper part of the belly section 3. The blowing pipe 10 may be provided on the lower part of the shaft 2, facing diagonally downwards, such that the blowing opening 12a of the blowing pipe 10 extends toward the belly part 3.

[0085] In the shaft section 2 or the belly section 3, the iron-based raw materials and coke that constitute the furnace interior are stacked alternately in layers. Depending on the particle size and condition of the furnace interior, the airflow resistance during gas injection may fluctuate alternately, causing variations in the amount of gas injected and potentially affecting the stability of the load descent. With this configuration, the amount of gas injected from the annular pipe 30 increases as the injection pipe insertion port 7, which has low airflow resistance, is increased. Therefore, a stable amount of gas can be ensured in accordance with the descent of the furnace interior.

[0086] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims.

[0087] According to this disclosure, a blowing pipe and blowing structure capable of improving load lowering stability are provided.

[0088] 1...Blast furnace 1d...Stave 1dG...Stave group 1dGU...Upper stave group 1dGL...Lower stave group 1d1...Notch 1d2...Through hole 1d3...Plate part 1d4...Protruding part 2...Shaft part 3...Berry part 7...Injection pipe insertion port 10...Injection pipe 12...Gas flow tube 12a...Injection opening 12A...Tip part 12B...Middle part 12C...Base part 121...Circumferential wall 122...Refrigerant flow path 13...Insulation material 16...Flow straightening member 50...Injection structure A...Core axis D...Radial direction O...Central axis α...Intersection angle θ...Angle

Claims

1. A blown-in pipe inserted into a blast furnace from the shaft or belly section, comprising a gas flow tube having a blown-in opening at its tip that opens into the furnace, wherein when the peripheral wall at the tip of the gas flow tube is viewed in a cross section perpendicular to the pipe axis direction of the blown-in pipe, the inner diameter dimension of the peripheral wall along the long axis direction is w (mm), and the inner diameter dimension of the peripheral wall along the short axis direction is h (mm), and w / h is greater than 1.

0.

2. The blowing pipe according to claim 1, wherein the w / h is 20.0 or less.

3. The blowpipe according to claim 1, wherein the cross-sectional shape of the peripheral wall is rectangular or elliptical.

4. The blowing pipe according to claim 1, wherein a refrigerant flow path is provided in the peripheral wall.

5. The blowing pipe according to claim 1, wherein an insulating material is provided on the inner surface of the peripheral wall of the gas flow pipe.

6. The inlet pipe according to claim 1, wherein the gas flow pipe has a flow straightening member inside.

7. The blowing pipe according to claim 1, wherein, when the blowing pipe is viewed in a cross-section along the axis of the pipe, the blowing opening is oriented diagonally downward.

8. A blowing structure comprising: a blowing pipe according to any one of claims 1 to 7; and a group of staves composed of a plurality of staves arranged on the furnace wall of the shaft portion or the belly portion of a blast furnace, wherein a blowing pipe insertion port is formed in the furnace wall of the shaft portion or the belly portion through which the blowing pipe is inserted.

9. The blowing structure according to claim 8, wherein the stave group comprises an upper stave group and a lower stave group positioned below it.

10. The blowing pipe insertion port is formed by a through hole formed in the fire-resistant material between the upper stave group and the lower stave group, the blowing structure according to claim 9.

11. The blowing pipe insertion port is formed below the boundary line between the left and right adjacent staves in the upper stave group, according to claim 9.

12. The blowing structure according to claim 9, wherein the boundary lines between adjacent staves on the left and right in the upper stave group and the boundary lines between adjacent staves on the left and right in the lower stave group are located at different positions in the circumferential direction of the furnace.

13. The blowing pipe insertion port is formed by a notch formed in at least one of the lower end of the stave of the upper stave group and the upper end of the stave of the lower stave group, according to claim 9.

14. The blowing structure according to claim 8, wherein the blowing pipe insertion port is formed by a through hole formed in the stave.

15. The blowing structure according to claim 14, wherein the stave has a plate portion and a projection portion that protrudes from the plate portion toward the core, and the blowing pipe insertion port is formed in the plate portion below the projection portion.

16. The blowing structure according to claim 8, wherein an abrasion-resistant layer is provided at the tip portion of the gas flow tube.

17. The injection structure according to claim 8, wherein, when viewed in a cross-section perpendicular to the core axis, the central axis of the injection tube, including the injection opening, intersects with respect to the radial direction of the furnace.

18. The blowing structure according to claim 17, wherein, when viewed in the cross-section, the angle of intersection of the central axis of the blowing pipe with respect to the radial direction of the furnace is greater than -60 degrees and less than 60 degrees.

19. The blowing structure according to claim 17, wherein when the blowing pipe is viewed in a cross-section along the axial direction of the pipe, the blowing opening is oriented diagonally downward.

20. The blowing structure according to claim 8, wherein two or more blowing pipe insertion openings are formed in the furnace wall of the shaft portion or the belly portion, and two or more blowing pipes communicating with a single gas supply pipe are inserted through the two or more blowing pipe insertion openings.

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