Blowing pipe, gas flow passage structure, and blowing structure

Abstract

This blowing pipe is inserted into a blast furnace from the shaft or the belly of the furnace, and comprises: an annular flange that is detachably attached to an outer wall of the shaft or the belly; a gas circulation pipe that is inserted into the flange and has a blowing opening that opens into the furnace; and a horn-shaped pipe that connects the flange and the gas circulation pipe. The horn-shaped pipe has a tapered part that decreases in diameter toward the tip side along the axial direction in which the central axis of the blowing pipe extends.

Description

Inlet pipe, gas flow path structure, and inlet structure

[0001] This disclosure relates to a blowing pipe, a gas flow path structure, and a blowing structure. This application claims priority under Japanese Patent Application No. 2025-048681, 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, where they are removed from the tap as pig iron and used in the next steelmaking process.

[0003] In typical blast furnace operations, coke and pulverized coal are used, resulting in the emission of large amounts of carbon dioxide (CO2). 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.

[0004] For example, Patent Document 1 contains CO and H ２ A blast furnace is disclosed that includes a device configured to introduce a high-temperature gas containing into the blast furnace shaft, i.e., from above the tuyere level.

[0005] As an example of a non-water-cooled injection pipe, Patent Document 2 discloses a configuration in which a refractory layer is provided between the inner casing and the outer casing of the injection device (injection pipe). Patent Document 2 also illustrates that a flange is provided on the injection pipe, and it is thought that the injection pipe is fixed to the outer wall of the blast furnace shaft via this flange. Furthermore, Patent Document 3 discloses a configuration in which the nozzle of the injection device (injection pipe) is equipped with a ceramic tip insertion part that has an insulating effect.

[0006] Japanese Patent Publication No. 2023-543051, International Publication No. 2022 / 058772, Japanese Patent Publication No. 2023-542557

[0007] In the above-mentioned Patent Document 1, CO and H ２ The injection device (injection tube) that blows high-temperature gas containing [unspecified substance] into the furnace is water-cooled to suppress wear. However, in order to suppress the temperature drop of the high-temperature gas passing through the inside of the injection device, it is desirable to use a non-water-cooled injection tube.

[0008] As described in Patent Document 2 above, by providing a flange on the blowing pipe and making this flange detachable from the outer wall of the shaft, the blowing pipe can be easily replaced. For example, if the blowing opening becomes blocked, the blowing pipe can be easily replaced, and blowing can be resumed more quickly.

[0009] However, when injecting high-temperature gas into a furnace, it is necessary to consider the deformation of the flange due to heat transfer from the gas circulating inside the injection pipe.

[0010] The present disclosure aims to provide an inlet pipe, a gas flow path structure, and an inlet structure that facilitate the replacement of the inlet pipe that injects reducing gas into the furnace from the shaft or belly section, and that can suppress deformation of the flange.

[0011] 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: an annular flange detachably attached to the outer wall of the shaft or belly section; a gas flow pipe inserted into the flange and having a blown-in opening that opens into the furnace; and a trumpet-shaped pipe connecting the flange and the gas flow pipe, wherein the trumpet-shaped pipe has a tapered section that decreases in diameter towards the tip along the axial direction in which the central axis of the blown-in pipe extends. [2] The blown-in pipe according to [1], further comprising an insulating structure covering the circumferential wall of the gas flow pipe. [3] The blown-in pipe according to [2], wherein the insulating structure comprises a first insulating material disposed between the gas flow pipe and the trumpet-shaped pipe in a radial direction perpendicular to the central axis; and a second insulating material disposed on the axial tip side of the trumpet-shaped pipe. [4] The inlet pipe according to any one of [1] to [3] above, wherein the gas flow pipe does not have a refrigerant flow path in the circumferential wall of the gas flow pipe. [5] The inlet pipe according to any one of [1] to [4] above, wherein in a cross-sectional view along the central axis, the angle formed between the tapered portion and the central axis is 20 degrees or more and 50 degrees or less. [6] The inlet pipe according to any one of [1] to [5] above, wherein the tapered portion extends in a curved manner in a cross-sectional view along the central axis. [7] The inlet pipe according to any one of [1] to [6] above, wherein the axial dimension of the trumpet pipe is 100 mm or more and 500 mm or less. [8] The inlet pipe according to any one of [1] to [7] above, wherein the trumpet pipe has a tapered portion and a base end cylindrical portion connected to the axial base end of the tapered portion and joined to the flange. [9] The inlet pipe according to any one of [1] to [8] above, wherein the trumpet pipe further has a tip end cylindrical portion connected to the axial tip end of the tapered portion and joined to the gas flow pipe.

[10] The inlet pipe according to any one of [1] to [9] above, wherein the flange has a refrigerant flow path.

[11] The inlet pipe according to any one of [1] to

[10] above, wherein when the inlet pipe is viewed in a longitudinal section along the central axis, the inlet opening is oriented diagonally downward.

[12] A gas flow path structure comprising a blowing pipe as described in any one of [1] to

[11] above, and a branch pipe connected to the blowing pipe from the axial base end side, wherein the branch pipe has an outer cylinder joined to the flange, a gas supply passage inserted inside the outer cylinder and connected to the gas flow pipe, and an insulating portion disposed between the outer cylinder and the gas supply passage, and the outer cylinder has an outer tapered portion that decreases in diameter towards the axial tip side, and the maximum diameter dimension of the outer tapered portion is greater than the maximum diameter dimension of the tapered portion.

[13] A blowing structure comprising a stave disposed on the furnace wall of the shaft portion or belly portion of a blast furnace, and a blowing pipe as described in any one of [1] to

[11] above.

[14] The blowing structure according to

[13] above, wherein the stave has a plate portion and a projection portion that protrudes from the plate portion toward the furnace core.

[15] The blowing structure according to

[14] , wherein the stave penetrates the plate portion and has an opening located below the protruding portion, and the blowing pipe is located within the opening.

[16] A blowing structure comprising a stave located on the furnace wall of the shaft portion or belly portion of a blast furnace, and a blowing pipe according to any one of [1] to

[11] , 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.

[17] The blowing structure according to

[16] , 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.

[18] The blowing structure according to

[16] or

[17] , wherein, when the blowing pipe is viewed in a longitudinal cross section along the central axis, the blowing opening is oriented diagonally downward.

[19] A blowing structure comprising a furnace wall of the shaft or belly section of a blast furnace and a blowing pipe as described in any one of [1] to

[11] above, wherein the gas flow pipe does not have a refrigerant flow path in the circumferential wall of the gas flow pipe, and the axial tip of the blowing opening is positioned in a range of 5 mm to 20 mm from the inner surface of the furnace wall toward the axial base end.

[20] A blowing structure comprising a stave disposed on the furnace wall of the shaft or belly section of a blast furnace, and a blowing pipe as described in any one of [1] to

[11] above, wherein the gas flow pipe does not have a refrigerant flow path in the circumferential wall of the gas flow pipe, and the stave has an opening that penetrates the plate section of the stave and in which the blowing pipe is disposed, and a hardened build-up disposed on the inner surface of the plate section around the opening.

[21] A blowing structure comprising an outer wall of the shaft or belly section of a blast furnace, and a blowing pipe as described in any one of [1] to

[11] above, wherein the outer wall has a steel shell and a mounting cylinder fixed to the steel shell, and the flange is supported by the mounting cylinder.

[22] A blowing structure comprising a furnace wall of the shaft or belly section of a blast furnace and a blowing pipe according to any one of [1] to

[11] above, wherein two or more blowing pipe insertion ports are formed in the furnace wall and spaced apart in the vertical direction, and two or more of the blowing pipes that communicate with a single gas supply pipe are inserted through the two or more blowing pipe insertion ports.

[23] A blowing structure comprising a stave arranged in the furnace wall of the shaft or belly section of a blast furnace and a blowing pipe according to any one of [1] to

[11] above, wherein a blowing pipe insertion port is formed in the stave through which the blowing pipe is inserted, and the blowing pipe insertion port is located on the periphery of the stave.

[24] The blowing structure according to

[23] above, wherein the blowing pipe insertion port is located at the corner of the periphery of the stave.

[0012] According to this disclosure, an inlet pipe, a gas flow path structure, and an inlet structure are provided that facilitate the replacement of the inlet pipe for injecting reducing gas into the furnace from the shaft or belly section, and suppress deformation of the flange.

[0013] Figure 1 is a schematic longitudinal cross-sectional view of a blast furnace according to this embodiment. Figure 2A is a schematic transverse cross-sectional view of the section II-II in Figure 1. Figure 2B is a transverse cross-sectional view at a position including the inlet pipe insertion port in a modified case in which the inlet pipe insertion port is formed in the center of the stave. Figure 3 is a longitudinal cross-sectional view showing the inlet pipe and gas flow path structure according to this embodiment, and is an enlarged view of section III in Figure 1. Figure 4 is a perspective cross-sectional view showing the positional relationship between the stave group and the inlet pipe insertion port in the inlet structure according to this embodiment. Figure 5A is a perspective cross-sectional view showing a first modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 5B 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 5C 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 5D 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 5E 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 5F 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 5G 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 5H 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 5I is a perspective cross-sectional view showing a ninth modified example of the positional relationship between the stave group and the inlet pipe insertion port. Figure 6 is a perspective cross-sectional view showing a part of a stave with a projection. Figure 7 is a schematic cross-sectional view showing a modified example of the blast furnace according to this embodiment. Figure 8 is a schematic longitudinal cross-sectional view showing a modified example of the blast furnace according to this embodiment. Figure 9 is a longitudinal cross-sectional view showing a modified example of the inlet pipe and gas flow path structure according to this embodiment, and is an enlarged view of part IX in Figure 8. Figure 10 is a longitudinal cross-sectional view showing a part of the first modified example of the inlet pipe according to this embodiment. Figure 11 is a longitudinal cross-sectional view showing a part of a second modified example of the blowing pipe according to this embodiment. Figure 12 is a longitudinal cross-sectional view showing a first modified example of the blowing structure according to this embodiment. Figure 13 is a front view of a stave used in the second modified example of the blowing structure according to this embodiment, viewed from the inside in the radial direction of the furnace. Figure 14 is a longitudinal cross-sectional view schematically showing a configuration in which two gas flow pipes are connected via two branch pipes.

[0014] A blast furnace 1 according to one embodiment of the present invention, as well as the blowing pipe 10, gas flow path structure 30, and blowing structure 50 provided in the blast furnace 1, will be described with reference to the drawings. The blast furnace 1 of this embodiment is equipment for reducing iron ore and extracting 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 specifically shown, iron-based raw materials and coke are charged into the blast furnace 1 alternately and in layers from the top 1a.

[0015] [Definition of Blast Furnace Direction] In this embodiment, 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 directions, 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.

[0016] Furthermore, the direction perpendicular to the core axis A is called the radial direction. Within 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 is sometimes simply called the core direction. Also, the direction that circles around the core axis A is called the circumferential direction.

[0017] [Components of the blast furnace] The 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Figure 2A is a cross-sectional view at a location including the blowing pipe insertion port 7 when the blowing pipe insertion port 7 is formed in the refractory material 1e (Figure 4, described later). In Figure 2A, the steel 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 location 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 5G, described later). In Figure 2B, the steel shell 1c, the refractory material 1e, and the stave 1d are present between adjacent blowing pipe insertion ports 7. As shown in Figures 2A and 2B, multiple blowing pipe insertion ports 7 are provided on the furnace wall of the shaft portion 2 of the blast furnace 1 at intervals from each other in the circumferential direction of the furnace. Note that 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 inlet pipe insertion ports 7 is not limited to eight; it may be seven or fewer, or nine or more. Also, they do not need to be spaced at equal intervals around the furnace.

[0023] A blowing pipe 10 for blowing reducing gas into the blast furnace 1 from the shaft portion 2 of the blast furnace 1 is inserted through the blowing pipe insertion opening 7. That is, the blast furnace 1 includes the blowing pipe 10, and the blowing pipe 10 is attached to the furnace wall of the shaft portion 2. The furnace wall includes a steel shell 1c, a refractory material 1e, and a stave 1d in this order from the outermost layer toward the inside in the furnace radial direction. The steel shell 1c is made of, for example, a steel plate. The stave 1d is a plate-shaped water-cooled metal member provided with a refrigerant channel for protecting the furnace wall from thermal load. The material of the stave 1d is not particularly limited, but is preferably copper or a copper alloy from the viewpoints of workability, thermal conductivity, cost, and the like, for example. A plurality of staves 1d are provided side by side in the vertical direction and the furnace circumferential direction so as to cover the furnace wall from the inside in the furnace radial direction. The refractory material 1e includes both a press-fitted material (monolithic refractory) and a stamped material (refractory capable of absorbing compressive deformation). Further, the refractory material 1e may have a portion provided as a joint closing the gap between staves 1d arranged adjacent to each other in the vertical direction or the furnace circumferential direction.

[0024] Reducing gas is blown from the blowing pipe 10. Blowing the reducing gas promotes the reduction of iron-based raw materials, and can reduce the coke ratio (the mass of coke required to produce 1 ton of hot metal) and the auxiliary reducing agent ratio (the mass of auxiliary reducing agent required to produce 1 ton of hot metal; when the auxiliary reducing agent is pulverized coal, this value is the pulverized coal ratio), thereby reducing carbon consumption in the blast furnace 1.

[0025] Among reducing gases, a hydrogen-based reducing gas refers to a gas that contains H in an elemental composition ratio of 30 mol% or more, and exists as a gas under standard conditions (0°C, 1 atmosphere). 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 H２ Gas, unsaturated hydrocarbon gas (C ２ H ４ , C ２ H ２ , C ３ H ６ (etc.) H ２ The gas does not contain carbon, and no thermal decomposition reaction occurs at the end of the inlet pipe 10, making it preferable from the viewpoint of reducing carbon consumption per unit. ２ Because the gas has low viscosity and density, it is also preferable from the viewpoint of permeability within the blast furnace 1.

[0026] Furthermore, while the hydrogen-based reducing gas may be injected into the blast furnace 1 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.

[0027] The temperature of the hydrogen-based reducing gas used in the blast furnace 1 according to this embodiment is not particularly limited. Preferably, the temperature of the hydrogen-based reducing gas is in the temperature range of room temperature to 1400°C. For example, the temperature of the hydrogen-based reducing gas may be in the temperature range of 800°C to 1200°C, or it may be in a high temperature range such as 1200°C to 1400°C.

[0028] Further, in the case where reducing gas is blown into the blast furnace from the shaft portion of the blast furnace 1, if a cavity called a raceway is formed in the vicinity of the furnace wall, there is a risk that the stability of descending burden in the furnace may be impaired. For this reason, it is preferable that the gas flow velocity of the reducing gas blown from the blowing pipe 10 is set to be slower than the flow velocity of gas such as hot air blown from the tuyere 6. Specifically, the gas flow velocity of the reducing gas blown from the blowing pipe 10 is, for example, 160 m / s or less so as to stably suppress the formation of the raceway. The gas flow velocity of the reducing gas blown from the blowing pipe 10 into the shaft portion 2 may be less than 200 m / s.

[0029] As shown in Fig. 3, the blowing pipe 10 has a multi-layer cylindrical shape centered on the central axis O. In the present embodiment, the central axis O of the blowing pipe 10 extends along the furnace radial direction (see Fig. 1, Fig. 2A and Fig. 2B). The blowing pipe 10 is inserted into a blowing pipe insertion opening 7 that penetrates the furnace wall of the shaft portion 2. That is, the blowing pipe 10 is inserted into the furnace from the shaft portion 2. In the present embodiment, the tip end of the blowing pipe 10 (the end on the inner side in the furnace radial 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 inward in the furnace radial direction).

[0030] As shown in Fig. 1, the blowing pipe 10 is connected to the annular pipe 8 via a branch pipe 20 arranged on the outer side of the blowing pipe 10 in the furnace radial direction. The annular pipe 8 supplies reducing gas to the blowing pipe 10 through the branch pipe 20. The annular pipe 8 has an annular shape centered on the furnace core axis A, and is arranged on the outer side of the shaft portion 2 in the furnace radial direction. In addition, the annular pipe 8 only needs to be arranged above the blowing pipe 10 (the blowing pipe insertion opening 7).

[0031] The gas flow path structure 30 according to the present embodiment includes a blowing pipe 10 and a branch pipe 20. As shown in FIGS. 1, 2A, and 2B, a plurality of gas flow path structures 30 are provided on the furnace wall of the shaft portion 2 spaced apart from each other in the furnace circumferential direction. Each of the plurality of gas flow path structures 30 preferably branches from the annular pipe 8 downward and toward the inside in the furnace radial direction. Note that in FIGS. 1, 2A, and 2B, the blowing pipe 10 and the branch pipe 20 are shown in a simplified (schematic) manner. Further, in FIG. 1, although the annular pipe 8 is arranged above the blowing pipe 10, it may be arranged below. In this case, the branch pipe 20 branches from the annular pipe 8 upward and toward the inside in the furnace radial direction.

[0032] [Definition of direction of blowing pipe] In FIG. 3, in the present embodiment, the direction in which the central axis O of the blowing pipe 10 extends, that is, the direction along the central axis O, is referred to as the axial direction. Of the axial directions, the direction from the branch pipe 20 toward the blowing pipe 10 is referred to as the axial distal end side or simply the distal end side, and the direction from the blowing pipe 10 toward the branch pipe 20 is referred to as the axial proximal end side or simply the proximal end side.

[0033] Further, the direction orthogonal to the central axis O is referred to as the radial direction. Of the radial directions, the direction approaching the central axis O is referred to as the radially inner side, and the direction away from the central axis O is referred to as the radially outer side. Further, the direction circling around the central axis O is referred to as the circumferential direction.

[0034] Note that, in order to more clearly distinguish from the above-mentioned furnace radial direction, the radial direction described above may be rephrased as the pipe radial direction. Further, in order to more clearly distinguish from the above-mentioned furnace circumferential direction, the circumferential direction described above may be rephrased as the pipe circumferential direction.

[0035] [Components of blowing pipe] As shown in FIG. 3, the blowing pipe 10 includes an annular flange 11 detachably attached to an outer wall of the shaft portion 2, a gas flow pipe 12 inserted through the flange 11, through which reducing gas flows, and having a blowing opening 12a opening into the furnace, a heat insulation structure 13 covering a peripheral wall of the gas flow pipe 12, and a flared pipe 14 connecting the flange 11 and the gas flow pipe 12.

[0036] In this embodiment, the iron shell 1c that constitutes the outer wall of the shaft portion 2 is fitted with a mounting cylinder 1f that protrudes outward in the radial direction from the outer circumferential surface of the iron shell 1c, and a mounting flange 1g that is connected to the outer end of the mounting cylinder 1f in the radial direction of the furnace. The mounting cylinder 1f and the mounting flange 1g are positioned to overlap with the blowing pipe insertion opening 7 of the furnace wall of the shaft portion 2 when viewed from the radial direction of the furnace.

[0037] The flange 11 of the blowing pipe 10 is sandwiched axially between the mounting flange 1g provided on the outer wall of the shaft portion 2 and the outer flange 21a of the branch pipe 20 (described later), and is detachably joined to each flange 1g and 21a by fastening members such as bolts and nuts (not shown). Furthermore, sealing members are provided between the mounting flange 1g and the flange 11, and between the flange 11 and the outer flange 21a. The sealing members are, for example, hydrogen (H) contained in the reducing gas. ２ These include spiral-shaped gaskets suitable for sealing applications such as those mentioned above.

[0038] The flange 11 is an annular plate shape centered on the central axis O. The pair of plate surfaces of the flange 11 face both sides in the axial direction (tip side and base side). The flange 11 contacts the mounting flange 1g from the axial base side (from the outside in the furnace radial direction).

[0039] The flange 11 has a refrigerant passage 11a through which a refrigerant, such as water, flows. In this embodiment, the refrigerant passage 11a is located inside the flange 11. The refrigerant passage 11a extends circumferentially around the central axis O inside the flange 11.

[0040] The flange 11 also has a plurality of pipe connection ports 11b, 11c provided on its outer circumferential surface. Each of the pipe connection ports 11b, 11c communicates with the refrigerant flow path 11a. The arrangement of the pipe connection ports 11b, 11c is not particularly limited. One of the pipe connection ports 11b, 11c is an inlet for supplying refrigerant to the refrigerant flow path 11a, and the other is an outlet for discharging refrigerant from the refrigerant flow path 11a. There may be multiple inlets and outlets.

[0041] The gas flow pipe 12 is cylindrical in shape with a central axis O. The gas flow pipe 12 extends axially along the central axis O. The gas flow pipe 12 is made of, for example, a heat-resistant alloy. The heat resistance temperature of the gas flow pipe 12 is set to be above the gas temperature of the reducing gas flowing inside the gas flow pipe 12. The gas flow pipe 12 does not have a refrigerant flow path in its circumferential wall. In other words, the inside of the circumferential wall of the gas flow pipe 12 (between the inner and outer surfaces of the circumferential wall) is solid.

[0042] The axial end of the gas flow pipe 12 is exposed inside the furnace of the shaft section 2. An injection opening 12a for injecting reducing gas into the furnace of the shaft section 2 is located at the axial end of the gas flow pipe 12. Although not specifically shown in the figures, when viewed from the axial end of the injection pipe 10, the injection opening 12a is circular in shape. In this embodiment, the injection opening 12a protrudes axially towards the end (inward in the furnace radial direction) from the inner surface of the stave 1d of the furnace wall of the shaft section 2. The axial base end of the gas flow pipe 12 is positioned so as not to protrude axially towards the base end beyond the flange 11. The tip of the injection opening 12a may be positioned so as not to protrude from the inner surface of the stave 1d of the furnace wall of the shaft section 2.

[0043] Furthermore, if the gas flow velocity of the reducing gas blown from the inlet pipe 10 into the shaft section 2 is, for example, 100 m / s, the reducing gas will not form a raceway in the furnace. Under this condition, the inner diameter of the inlet opening 12a per inlet pipe is calculated to be, for example, several tens of centimeters. Since it is desirable for the gas flow velocity to be high enough to prevent the formation of a raceway, a lining member (not shown) may be provided at the inlet opening 12a. The opening shape (cross-sectional shape) of the lining member provided to reduce the inner diameter or cross-sectional area of ​​the inlet opening 12a is not limited to a circle, but may be, for example, elliptical, crescent-shaped (upper crescent, lower crescent, side crescent (vertical crescent)), curved, etc. This allows for adjustment not only of the gas flow velocity of the reducing gas, but also of the ejection direction and ejection angle of the reducing gas.

[0044] As shown in Figure 3, when the inlet pipe 10 is viewed in a vertical cross-section (a longitudinal cross-section along the central axis O) including the inlet opening 12a, the inlet opening 12a is oriented diagonally downward. In the longitudinal cross-sectional view shown in Figure 3, in this embodiment, the inlet opening 12a extends axially toward the base end as it goes downward. In this longitudinal cross-sectional view, the upper end of the inlet opening 12a protrudes axially toward the tip (inward in the furnace radial direction) than the lower end.

[0045] The trumpet-shaped tube (tapered tube) 14 is cylindrical with a central axis O as its center and extends in the axial direction. Specifically, the trumpet-shaped tube 14 is multi-stage cylindrical, and its diameter differs from one another at each position in the axial direction. The diameter of the axial tip of the trumpet-shaped tube 14 is smaller than the diameter of the axial base of the trumpet-shaped tube 14. The trumpet-shaped tube 14 has a portion (tapered portion 14a, described later) in which the diameter decreases as it approaches the axial tip.

[0046] The axial tip of the flared tube 14 is connected to the outer surface of the gas flow pipe 12. The axial base end of the flared tube 14 is connected to the inner circumference of the flange 11. The axial dimension (total length) L of the flared tube 14 is, for example, 100 mm or more and 500 mm or less. The flared tube 14 is positioned within the inlet pipe insertion port 7, extending from the outer end in the radial direction of the furnace, through the mounting cylinder 1f, and through the mounting flange 1g.

[0047] The trumpet-shaped pipe 14 has a tapered portion 14a that decreases in diameter as it approaches the tip along the axial direction, a base cylindrical portion 14b connected to the axial base end of the tapered portion 14a and joined to the flange 11, and a tip cylindrical portion 14c connected to the axial tip end of the tapered portion 14a and joined to the gas flow pipe 12.

[0048] The tapered portion 14a has a tapered cylindrical shape, with its diameter decreasing towards the tip in the axial direction. The tapered portion 14a is made of, for example, a heat-resistant alloy. The heat resistance temperature of the tapered portion 14a is set to be, for example, below the heat resistance temperature of the gas flow pipe 12. As shown in Figure 3, in a cross-sectional view along the central axis O, the angle θ formed between the tapered portion 14a and the central axis O is, for example, 20 degrees or more and 50 degrees or less.

[0049] The base end cylindrical portion 14b is cylindrical in shape with respect to the central axis O. The base end cylindrical portion 14b extends axially along the central axis O. The base end cylindrical portion 14b is made of a material having a heat resistance temperature equal to or lower than that of the tapered portion 14a, for example, a heat-resistant alloy. The diameter of the base end cylindrical portion 14b is approximately the same as the diameter of the base end of the tapered portion 14a and the diameter of the inner circumference of the flange 11. The tip of the base end cylindrical portion 14b and the base end of the tapered portion 14a are joined by welding or the like. The base end of the base end cylindrical portion 14b and the inner circumference of the flange 11 are joined by welding or the like.

[0050] The tip-side cylindrical portion 14c is cylindrical in shape with respect to the central axis O. The tip-side cylindrical portion 14c extends axially along the central axis O. The gas flow pipe 12 is joined inside the tip-side cylindrical portion 14c. The tip-side cylindrical portion 14c is made of, for example, a heat-resistant alloy. The tip-side cylindrical portion 14c is made of a material having a heat resistance temperature equivalent to that of the gas flow pipe 12. The diameter of the tip-side cylindrical portion 14c is approximately the same as the diameter of the tip of the tapered portion 14a. The inner circumference of the tip-side cylindrical portion 14c and the outer circumference of the gas flow pipe 12 are joined by welding or the like. The base end of the tip-side cylindrical portion 14c and the tip of the tapered portion 14a are also joined by welding or the like. The materials of the gas flow pipe 12, tapered portion 14a, base-side cylindrical portion 14b, and tip-side cylindrical portion 14c are, for example, heat-resistant stainless steel, Ni-based alloy, etc.

[0051] The thermal insulation structure 13 is cylindrical in shape with a central axis O at its center and extends in the axial direction. The thermal insulation structure 13 is positioned adjacent to the gas flow pipe 12 on the radially outer side of the gas flow pipe 12's peripheral wall. The thermal insulation structure 13 covers the gas flow pipe 12's peripheral wall from the radially outer side.

[0052] The thermal insulation structure 13 is divided axially at the tip and base ends of the tapered portion 14a of the trumpet pipe 14. Specifically, the thermal insulation structure 13 has a first thermal insulation material 13a positioned between the gas flow pipe 12 and the trumpet pipe 14 in the radial direction perpendicular to the central axis O, and a second thermal insulation material 13b positioned at the axial tip end of the trumpet pipe 14. The first thermal insulation material 13a and the second thermal insulation material 13b are each positioned radially outward from the gas flow pipe 12, extending around the entire circumference. The first thermal insulation material 13a and the second thermal insulation material 13b differ from each other, for example, in their suitable operating temperature range and material. The first thermal insulation material 13a and the second thermal insulation material 13b are mainly Al ２ O ３ Monomorphic refractories containing, mainly Al ２ O ３ and SiO ２ Examples include amorphous refractories containing [unclear material], microporous insulation materials, and high-temperature insulating wool.

[0053] The first insulating material 13a is substantially cylindrical in shape. The first insulating material 13a is positioned between the inner circumferential surfaces of the tapered portion 14a, the base end cylindrical portion 14b, and the flange 11, and the outer circumferential surface of the gas flow pipe 12.

[0054] The second insulating material 13b is substantially cylindrical in shape. The second insulating material 13b is positioned axially towards the tip of the first insulating material 13a. The second insulating material 13b is positioned radially outward of the portion of the gas flow pipe 12 that is located towards the tip of the trumpet pipe 14, radially outward of the tip cylindrical portion 14c, and radially outward of the tapered portion 14a.

[0055] [Components of the gas flow path structure] The gas flow path structure 30 according to this embodiment comprises the aforementioned inlet pipe 10 and a branch pipe 20, which will be described later.

[0056] [Components of the branch pipe] The branch pipe 20 is connected to the inlet pipe 10 from its axial base end and supplies reducing gas to the inlet pipe 10. The branch pipe 20 has an outer casing 21 joined to the flange 11, a gas supply passage 22 inserted inside the outer casing 21 and connected to the gas flow pipe 12, and a heat insulating section 23 positioned between the outer casing 21 and the gas supply passage 22.

[0057] The outer casing 21 is cylindrical and extends in the axial direction. Specifically, the outer casing 21 is multi-stage cylindrical, with different diameter dimensions at each position in the axial direction. The outer casing 21 includes an annular outer flange 21a joined to the mounting flange 1g of the outer wall of the shaft portion 2 via the flange 11 of the blowing pipe 10, a small-diameter portion 21b located on the axial base end side of the outer flange 21a and connected to the outer flange 21a, an outer tapered portion 21c located on the axial base end side of the small-diameter portion 21b and connected to the small-diameter portion 21b, and a large-diameter portion 21d located on the axial base end side of the outer tapered portion 21c and connected to the outer tapered portion 21c.

[0058] The outer flange 21a is an annular plate shape centered on the central axis O. The pair of plate surfaces of the outer flange 21a face both sides in the axial direction (tip side and base side). The outer flange 21a contacts the flange 11 of the blowing pipe 10 from the axial base side (from the outside in the furnace radial direction).

[0059] The small-diameter portion 21b is cylindrical in shape with respect to the central axis O. The small-diameter portion 21b extends axially along the central axis O. The axial tip of the small-diameter portion 21b is joined to the inner circumference of the outer flange 21a by welding or the like. In this embodiment, the axial base end of the gas flow pipe 12 of the blowing pipe 10 is the joint surface between the flange 11 and the outer flange 21a, but it may also be inserted into the outer flange 21a and into the small-diameter portion 21b.

[0060] The outer tapered portion 21c has a tapered cylindrical shape that widens in diameter towards the base end in the axial direction. In other words, the outer tapered portion 21c narrows in diameter towards the tip in the axial direction. The axial tip of the outer tapered portion 21c is joined to the axial base end of the small diameter portion 21b by welding or the like. The diameter of the axial base end of the outer tapered portion 21c (i.e., the maximum diameter of the outer tapered portion 21c) is larger than the diameter of the axial base end of the tapered portion 14a of the trumpet pipe 14 described above (i.e., the maximum diameter of the tapered portion 14a).

[0061] The large-diameter portion 21d is cylindrical in shape with respect to the central axis O. The large-diameter portion 21d extends axially along the central axis O. The axial tip of the large-diameter portion 21d is joined to the axial base end of the outer tapered portion 21c by welding or the like.

[0062] The gas supply channel 22 extends axially with respect to the central axis O. The axial end of the gas supply channel 22 is connected to the axial base end of the gas flow pipe 12. The gas supply channel 22 and the gas flow pipe 12 are in communication internally.

[0063] The heat insulating section 23 is provided between the gas supply passage 22 and the outer casing 21 in the radial direction. Specifically, the heat insulating section 23 is positioned radially outside the gas supply passage 22 and radially inside the outer casing 21.

[0064] In this embodiment, the branch pipe 20 is axially separable by a detachable flange structure 24. That is, the branch pipe 20 is configured to be separable into a tip end portion and a base end portion of the flange structure 24. In the illustrated example, the flange structure 24 is provided in a part of the axial direction of the large diameter portion 21d. The flange structure 24 has a pair of flange bodies 24a and 24b that face each other in the axial direction, and fastening members such as bolts and nuts (not shown) that detachably join the pair of flange bodies 24a and 24b together.

[0065] [Injection Structure] The injection structure 50 of this embodiment, which injects reducing gas into the furnace from the shaft section 2 of the blast furnace 1, comprises the furnace wall of the shaft section 2, staves 1d arranged on this furnace wall, and an injection pipe 10. The positional relationship between the stave group 1dG and the injection pipe insertion port 7 in the injection structure 50 of this embodiment will be explained in detail below. Note that Figures 4 to 6 mainly show the staves 1d, and the injection pipe 10 is not shown.

[0066] As shown in Figure 4, 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.

[0067] The following describes a preferred configuration for the inlet pipe insertion port 7 based on Figures 5A to 5F.

[0068] As shown in the modified example in Figure 5A, the blowing pipe insertion port 7 may be formed in the refractory material 1e 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.

[0069] Furthermore, as shown in the modified example in Figure 5B, 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.

[0070] Furthermore, as shown in the modified examples in Figures 5C, 5D, 5E, and 5F, the blowing 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.

[0071] In the modified example shown in Figure 5C, 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.

[0072] In the modified example shown in Figure 5D, 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.

[0073] In the modified example shown in Figure 5E, 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.

[0074] In the modified example shown in Figure 5F, 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.

[0075] According to the modifications shown in Figures 5C, 5D, 5E, and 5F, 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.

[0076] In the modified example shown in Figure 5G, 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 diameter 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 5H, the inlet pipe insertion port 7 may be formed by a notch 1d1 formed in at least one of a pair of staves 1d adjacent to each other in the furnace circumferential direction. Note that in Figure 5H, 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.

[0077] In the modified example shown in Figure 5I, a blown-in pipe insertion port 7 is formed in the stave 1d through which the blown-in pipe 10 is inserted, and the blown-in pipe insertion port 7 is located on the periphery of the stave 1d. Specifically, in this embodiment, the stave 1d is in the shape of a rectangular plate, and the periphery of the stave 1d includes four sides and four corners. In the example shown in Figure 5I, the blown-in pipe insertion port 7 is located on one of the corners of the periphery of the stave 1d. According to this embodiment, a blown-in pipe insertion port 7 that penetrates the stave 1d can be provided without reducing the cooling capacity of the stave 1d (stave cooling capacity), or while suppressing the reduction. In Figure 5I, an example is shown in which the blown-in pipe insertion port 7 is formed by a notch 1d1, but it is not limited to this, and may be formed by a through hole 1d2.

[0078] Furthermore, in the modified example shown in Figure 6, the stave 1d is a stave 1d with a projection. As shown in Figure 6, the stave 1d has a plate portion 1k and a projection 1m that protrudes inward in the radial direction of the furnace (towards the furnace core) from the plate portion 1k. The pair of plate surfaces of the plate portion 1k face both sides (inward and outward) in the radial direction of the furnace. A refrigerant water channel (not shown) is also provided inside the plate portion 1k. Although not specifically shown, the refrigerant water channel is connected to a water inlet that supplies cooling water to the refrigerant water channel from the outside of the shaft portion 2 in the radial direction of the furnace, and to a drain outlet that discharges cooling water from the refrigerant water channel to the outside of the shaft portion 2 in the radial direction of the furnace.

[0079] The protruding portion 1m extends in the direction of the furnace core from the plate surface of the plate portion 1k facing inward in the furnace radial direction and extends in the furnace circumferential direction. The protruding portion 1m is rib-shaped. The amount of protrusion P2 of the protruding portion 1m inward in the furnace radial direction from the inner surface of the plate portion 1k 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 1k. In addition, multiple protruding portions 1m are provided at intervals from each other in the vertical direction. As shown in Figure 6, when multiple protruding portions 1m are provided on the stave 1d, a self-lining effect can be obtained by having the descending furnace contents enter between the upper and lower protruding portions 1m.

[0080] Furthermore, the stave 1d has an opening 1j that penetrates the plate portion 1k and is located below the protruding portion 1m. The opening 1j is located below the protruding portion 1m and adjacent to the protruding portion 1m. The opening 1j penetrates the stave 1d in the direction of its plate thickness (i.e., the direction of the furnace diameter) and constitutes part of the blown-in pipe insertion opening 7 of the furnace wall. The opening 1j may be a circular hole that penetrates the stave 1d in the direction of its plate thickness, similar to the through hole 1d2, or multiple openings 1j may be circular holes, similar to the notch 1d1. The blown-in pipe 10 is placed inside the opening 1j. The shape of the opening 1j can be selected according to the shape of the blown-in pipe 10.

[0081] As shown in Figure 3, the blowing structure 50 of this embodiment comprises the outer wall of the shaft portion 2 and the blowing pipe 10. The outer wall of the shaft portion 2 has a steel shell 1c and a mounting cylinder 1f fixed to the steel shell 1c, and a flange 11 is supported on the mounting cylinder 1f. Specifically, the mounting cylinder 1f is cylindrical in shape and protrudes outward from the steel shell 1c in the radial direction of the furnace, and extends axially along the central axis O of the blowing pipe 10. The outer wall of the shaft portion 2 also has a mounting flange 1g fixed to the mounting cylinder 1f. The flange 11 of the blowing pipe 10 is supported on the mounting cylinder 1f via the mounting flange 1g. With this configuration, the blowing pipe 10 can be stably fixed to the outer wall of the shaft portion 2.

[0082] [Effects of this Embodiment] In this embodiment described above, when the fastening member that joins the flange 11 to the outer wall (mounting flange 1g) of the shaft portion 2 is released and the flange 11 is removed from the outer wall of the shaft portion 2, the gas flow pipe 12 connected to the flange 11 via the flared pipe 14, and the heat insulating structure 13 arranged radially outside the gas flow pipe 12 are removed as a whole (they are easily removed as an assembly). Therefore, the blowing pipe 10 can be easily replaced and the blowing of reducing gas can be quickly resumed. In addition, in this embodiment, even if the gas flow pipe 12 becomes hot, a temperature gradient is created by the tapered portion 14a of the flared pipe 14, which suppresses the transfer of high heat to the flange 11 and suppresses deformation of the flange 11.

[0083] In this embodiment, the inlet pipe 10 may also be non-water-cooled. If the gas flow pipe 12 is not water-cooled, the temperature drop of the reducing gas flowing inside the gas flow pipe 12 is suppressed, and the temperature drop inside the furnace is suppressed. In other words, the reducing gas can be supplied into the furnace from the shaft section 2 while maintaining a high gas temperature, so the reaction between the reducing gas and the raw materials inside the furnace can be promoted, productivity can be improved, operating costs can be reduced, and coke consumption and CO2 in the blast furnace process can be reduced. ２ This will make it possible to reduce emissions.

[0084] Based on the above, this embodiment provides an inlet pipe 10, a gas flow path structure 30, and an inlet structure 50 that allows for easy replacement of the inlet pipe 10 and quick resumption of inletting, and suppresses deformation of the flange 11. Furthermore, by employing a non-water-cooled gas flow pipe 12, the decrease in the gas temperature of the reducing gas injected into the furnace from the shaft section 2 can be suppressed, thereby suppressing the decrease in furnace temperature and improving productivity.

[0085] In this embodiment, the heat insulating structure 13 includes a first heat insulating material 13a positioned radially between the gas flow pipe 12 and the trumpet pipe 14, and a second heat insulating material 13b positioned at the axial end of the trumpet pipe 14.

[0086] In this case, the material of each insulation material 13a and 13b of the insulation structure 13 can be optimized depending on the location where it is placed. Specifically, for example, appropriate insulation functions can be set for the first insulation material 13a and the second insulation material 13b, respectively, so that stable durability can be ensured according to the layout, and material costs can be reduced by suppressing excessive specifications.

[0087] Furthermore, in this embodiment, as shown in Figure 3, the angle θ formed between the tapered portion 14a and the central axis O in a cross-sectional view along the central axis O is 20 degrees or more and 50 degrees or less.

[0088] If the angle θ is 20 degrees or more, the inclination of the tapered section 14a is prevented from becoming too gentle, and the axial dimension of the tapered section 14a is kept small. This prevents the axial dimension L of the flared pipe 14 from becoming too long. Since the weight of the flared pipe 14 is prevented from becoming too heavy, the overall weight of the inlet pipe 10 can be reduced, making the replacement of the inlet pipe 10 easier. Also, if the angle θ is 50 degrees or less, the inclination of the tapered section 14a is prevented from becoming too steep. Therefore, the problem of the force restraining the thermal expansion of the gas flow pipe 12 becoming too large due to the steeply inclined tapered section 14a (excessive thermal stress on the gas flow pipe 12) can be prevented.

[0089] In this embodiment, the axial dimension L of the trumpet tube 14 is 100 mm or more and 500 mm or less.

[0090] By having an axial dimension L of 100 mm or more, the temperature gradient function provided by the flared pipe 14 is stably obtained, and the deformation of the flange 11 is more stably suppressed. Furthermore, by having an axial dimension L of 500 mm or less, the weight of the flared pipe 14 is prevented from becoming too heavy, and the replacement of the blowing pipe 10 can be easily performed.

[0091] In this embodiment, the trumpet pipe 14 has a tapered portion 14a, a base cylindrical portion 14b connected to the axial base end of the tapered portion 14a and joined to the flange 11, and a tip cylindrical portion 14c connected to the axial tip end of the tapered portion 14a and joined to the gas flow pipe 12.

[0092] In this case, by appropriately adjusting the axial dimensions of the tip cylindrical portion 14c and the base cylindrical portion 14b, the temperature gradient of the entire trumpet tube 14 can be made gentler or thermal stress can be reduced. Furthermore, for example, if the temperature of the reducing gas flowing through the gas flow pipe 12 is below a predetermined value (for example, if the gas temperature is lower than the heat resistance temperature of the tapered portion 14a), the tip of the tapered portion 14a may be directly joined to the gas flow pipe 12 without providing the tip cylindrical portion 14c in the trumpet tube 14.

[0093] If the gas flow pipe 12 does not have a refrigerant flow path in its peripheral wall, the wall thickness of the gas flow pipe 12 can be reduced to, for example, about 5 mm. This makes the blowing pipe 10 lighter and simplifies the replacement of the blowing pipe 10.

[0094] Furthermore, in this embodiment, the flange 11 can have a refrigerant flow path 11a. In this case, the flange 11 is cooled by the refrigerant flowing through the refrigerant flow path 11a, so the deformation of the flange 11 is more stably suppressed.

[0095] In this embodiment shown in Figure 3, when the blowing pipe 10 is viewed in a vertical cross-section along the central axis O, the blowing opening 12a is oriented diagonally downward. In this case, it becomes difficult for the furnace contents that are being loaded downwards to enter the blowing opening 12a. This suppresses the blockage of the blowing opening 12a.

[0096] Furthermore, in the gas flow path structure 30 according to this embodiment, the maximum diameter dimension of the outer tapered portion 21c of the outer cylinder 21 is larger than the maximum diameter dimension of the tapered portion 14a of the trumpet tube 14.

[0097] In this case, the outer casing 21 of the branch pipe 20 is tapered in diameter towards the axial end in the outer tapered section 21c before being joined to the flange 11. As a result, the diameter of the flange 11 is reduced, and the diameter of the flared pipe 14 connecting the flange 11 and the gas flow pipe 12 can also be reduced. Since the flared pipe 14 can be made smaller and lighter, the workability (replaceability) when replacing the blowing pipe 10 is improved.

[0098] Furthermore, in the injection structure 50 shown in Figure 6, the stave 1d has a plate portion 1k, a projection 1m that protrudes from the plate portion 1k toward the core, and an opening 1j that penetrates the plate portion 1k and is located below the projection 1m, with the injection pipe 10 positioned within the opening 1j.

[0099] In this case, the protruding portion 1m of the stave 1d is positioned to cover the injection opening 12a of the injection pipe 10 from above, making it difficult for the material of the furnace interior to enter through the injection opening 12a. Therefore, the effect of preventing blockage of the injection opening 12a is further enhanced. Furthermore, the amount of protrusion P2 of the protruding portion 1m inward in the furnace radial direction from the inner surface of the plate portion 1k may be greater than or equal to the amount of protrusion P1 of the injection pipe 10 inward in the furnace radial direction from the inner surface of the plate portion 1k. In this case, the above effect is enhanced more stably.

[0100] Furthermore, to prevent fine powders and other materials from the furnace contents that descend within the furnace from entering the injection opening 12a, it is more preferable that the tip of the injection pipe 10 protrudes from the inner surface of the furnace wall of the shaft section 2 (see the protrusion amount P1 in Figure 3). Also, by having the tip of the injection 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 injection opening 12a and easier injection of reducing gas can be expected. In addition, by having the tip of the injection 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 possible to supply reducing gas from the middle to the periphery of the furnace and improve the reduction efficiency. As shown in Figure 3, it is preferable that the injection opening 12a is oriented diagonally downward.

[0101] [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.

[0102] Figure 7 is a schematic cross-sectional view showing a modified example of the blast furnace 1 of the above-described embodiment, specifically a cross-sectional view of the shaft section 2. In Figure 7, the shapes of the blowing pipe 10 and the gas flow path structure 30 are simplified (schematically) in the diagram.

[0103] In this modified example, as shown in Figure 7, 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 around the core axis A) as they move inward in the radial direction D. The direction in which the central axes O of the injection tubes 10 extend may also be a clockwise direction around the core axis A as they move inward in the radial direction D.

[0104] In this case, the reducing gas is injected into the furnace from the injection opening 12a of the injection pipe 10 toward the inside in the radial direction, and then 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 area of ​​the 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, the loading stability of the furnace contents is further enhanced.

[0105] 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 7, 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.

[0106] Figure 8 is a schematic longitudinal cross-sectional view showing a modified example of the blast furnace 1 of the above-described embodiment. Note that in Figure 8, the shapes of the injection pipe 10 and the gas flow path structure 30 are simplified (schematically) in their representation. Figure 9 is a longitudinal cross-sectional view showing a modified example of the injection pipe 10 and the gas flow path structure 30 of the above-described embodiment, and is an enlarged view of section VII of Figure 8.

[0107] In this modified configuration, as shown in Figures 8 and 9, 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, the blowing opening 12a is angled downwards. Specifically, the central axis O of the blowing pipe 10 extends downwards as it approaches the axial end (inward in the furnace radial direction). This causes the blowing opening 12a to angle downwards. In this modified configuration as well, the entry of furnace contents into the blowing opening 12a is suppressed. Therefore, blockage of the blowing opening 12a is suppressed. The modified configuration shown in Figure 7 and the modified configurations shown in Figures 8 and 9 may be combined as appropriate.

[0108] Furthermore, in the modified example shown in Figure 9, 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 9, 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.

[0109] 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 9, the injection opening 12ab (12a) may be arranged so as to be flush with the inner surface of the furnace wall of the shaft portion 2 (the amount of protrusion of the injection opening from the inner surface of the furnace wall is 0 mm).

[0110] Furthermore, although an example was given in which the staple 1d has a plate portion 1k and a protruding portion 1m, it is not limited to this. The staple 1d does not have to have a protruding portion 1m.

[0111] Furthermore, in the above-described embodiment, as shown in Figure 3, an example was given in which the tapered portion 14a of the trumpet pipe 14 extends linearly radially inward as it approaches the tip in the axial direction, in a cross-sectional view along the central axis O, but the configuration is not limited to this. Here, Figures 10 and 11 show a longitudinal cross-section of a part of the blowing pipe 10 of a modified example of the above-described embodiment. As shown in Figures 10 and 11, in a cross-sectional view along the central axis O, the tapered portion 14a may extend in a curved shape. In this cross-sectional view, the tapered portion 14a may extend in a concave or convex curved shape as it approaches the tip in the axial direction, in a radial direction.

[0112] More specifically, in the modified example shown in Figure 10, the tapered portion 14a has a first curved portion 14aa that extends in a concave curve shape and a second curved portion 14ab that extends in a convex curve shape in a cross-sectional view along the central axis O. The axial tip of the first curved portion 14aa is connected to the outer surface of the gas flow pipe 12. The second curved portion 14ab is located axially closer to the base end than the first curved portion 14aa. The axial base end of the second curved portion 14ab is connected to the axial tip of the base end cylindrical portion 14b. Furthermore, the tapered portion 14a and the base end cylindrical portion 14b are integrally formed from a single member. In the modified example shown in Figure 11, the tapered portion 14a extends in a concave curve shape in a cross-sectional view along the central axis O. The axial tip of the tapered portion 14a is connected to the axial base end of the tip end cylindrical portion 14c. The axial base end of the tapered portion 14a is connected to the axial tip of the base end cylindrical portion 14b. Furthermore, the tapered portion 14a and the tip end cylindrical portion 14c are integrally formed from a single member. With this configuration, the total length of the tapered portion 14a is larger compared to the case where the tapered portion 14a extends in a straight line in cross-section, resulting in a gentler temperature gradient.

[0113] Furthermore, in the modified example shown in Figure 12, the blowing structure 50 comprises the furnace wall of the shaft portion 2 and the blowing pipe 10. The gas flow pipe 12 does not have a refrigerant flow path on its peripheral wall. In this modified example, when reducing gas is not flowing inside the gas flow pipe 12 (before the gas flow pipe 12 undergoes thermal expansion), the axial tip of the blowing opening 12a is positioned within a range of 5 mm to 20 mm from the inner surface of the furnace wall toward the base end in the axial direction. The "inner surface of the furnace wall" refers to the inner surface portion of the furnace wall where the blowing pipe insertion port 7 is formed, and is not limited to the inner surface of the plate portion 1k of the stave 1d described above, but may also refer to the inner surface of the refractory material 1e.

[0114] With the above configuration, when reducing gas at a predetermined temperature or higher flows inside the gas flow pipe 12 and the gas flow pipe 12 has thermally expanded in accordance with the gas temperature, the axial tip of the injection opening 12a is positioned substantially flush with the inner surface of the furnace wall of the shaft section 2. "Substantially flush" means that the difference (axial dimension) between the axial position of the tip of the injection opening 12a and the axial position of the inner surface of the furnace wall of the shaft section 2 (the inner surface of the plate section 1k of the stave 1d in the illustrated example) is ±5 mm or less.

[0115] Furthermore, the axial tip position of the injection opening 12a before thermal expansion can be calculated within the above numerical range (5 mm to 20 mm) based on the linear expansion coefficient according to the material of the gas flow pipe 12, the injection gas temperature, and the axial length of the gas flow pipe 12 according to the furnace wall thickness such as the staves 1d. According to the above modification, even if the gas flow pipe 12 is of a non-water-cooled type and is prone to thermal expansion, the tip of the gas flow pipe 12 (injection opening 12a) is prevented from protruding significantly into the furnace from the inner surface of the furnace wall. This prevents the tip of the gas flow pipe 12 from being worn down by the furnace contents that descend (fall) inside the furnace.

[0116] Furthermore, in the modified example shown in Figure 13, the blowing structure 50 comprises a stave 1d arranged on the furnace wall of the shaft portion 2 and a blowing pipe 10 (not shown), and the gas flow pipe 12 does not have a refrigerant flow path on its peripheral wall. The stave 1d has an opening 1j that penetrates the plate portion 1k of the stave 1d and in which the blowing pipe 10 is arranged, and an annular hardened buildup 1n arranged around the opening 1j on the inner surface of the plate portion 1k. It is preferable to select a material for the hardened buildup 1n that has excellent heat resistance and / or wear resistance. When the temperature of the gas flow pipe 12 rises and its strength decreases, the tip tends to be selectively worn by the furnace contents. In the modified example described above, problems such as thinning of the stave 1d around the gas flow pipe 12, which can be caused by such selective wear, can be suppressed by the hardened buildup 1n formed around the opening 1j.

[0117] 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 8 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 14, two inlet pipe insertion ports 7 spaced apart in the vertical direction are formed in the furnace wall of the shaft portion 2, and two inlet pipes 10 that communicate with a single gas supply pipe (the annular pipe 8 in the example shown in Figure 14) via branch pipes 20 are inserted into the two inlet pipe insertion ports 7. The "two inlet pipe insertion ports 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.

[0118] Furthermore, in the above-described embodiment, an example was given in which the refrigerant flow path 11a of the flange 11 is located inside the flange 11, but this is not limited to this. Although not specifically shown, the refrigerant flow path of the flange may be provided externally to the flange, for example, by attaching a pipe to the outer surface of the flange.

[0119] Furthermore, in the above-described embodiment, it was explained that the first insulating material 13a and the second insulating material 13b of the insulating structure 13 have different preferred operating temperature ranges and materials, but this is not limited to this. The first insulating material 13a and the second insulating material 13b may have the same preferred operating temperature range and material. Also, in the above-described embodiment and the above-described modification, the blowing pipe 10 was described as being provided on the furnace wall of the shaft portion 2 as an example, but the blowing pipe 10 may be provided on the furnace wall of the belly portion 3. It is preferable that the blowing pipe 10 be provided on the lower part of the shaft portion 2 or on the upper part of the belly portion 3. The blowing pipe 10 may be provided on the lower part of the shaft portion 2, facing diagonally downward, such that the blowing opening 12a of the blowing pipe 10 extends toward the belly portion 3.

[0120] This disclosure may combine the configurations described in the embodiments and modifications described above, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of this disclosure. Furthermore, this disclosure is not limited by the embodiments described above, but is limited only by the claims.

[0121] According to this disclosure, an inlet pipe, a gas flow path structure, and an inlet structure are provided that facilitate the replacement of the inlet pipe for injecting reducing gas into the furnace from the shaft or belly section, and suppress deformation of the flange.

[0122] 1...Blast furnace 1c...Steel shell 1d...Stave 1f...Mounting cylinder 1j...Opening 1k...Plate section 1m...Protruding section 1n...Hardened overlay 2...Shaft section 3...Berry section 7...Inlet pipe insertion port 8...Annular pipe (gas supply pipe) 10...Inlet pipe 11...Flange 11a...Refrigerant flow path 12...Gas flow pipe 12a, 12aa, 12ab...Inlet opening 13...Insulation structure 13a...First insulation material 13b...Second insulation material 14...Trumpet pipe 14a...Tapered section 14b...Base end cylindrical section 14c...Tip end cylindrical section 20...Branch pipe 21...Outer cylinder 21c...Outer tapered section 22...Gas supply flow path 23...Insulation section 30...Gas flow path structure 50...Inlet structure A...Core axis D...Radial direction L: Axial dimension of the bell-shaped tube; O: Central axis; α: Intersection angle; θ: Angle

Claims

1. A blowing pipe inserted into a blast furnace from the shaft or belly section, comprising: an annular flange detachably attached to the outer wall of the shaft or belly section; a gas flow pipe inserted into the flange and having a blowing opening that opens into the furnace; and a trumpet-shaped pipe connecting the flange and the gas flow pipe, wherein the trumpet-shaped pipe has a tapered section that decreases in diameter towards the tip along the axial direction from which the central axis of the blowing pipe extends.

2. The blowing pipe according to claim 1, further comprising an insulating structure covering the peripheral wall of the gas flow pipe.

3. The inlet pipe according to claim 2, wherein the insulated structure comprises a first insulated material disposed between the gas flow pipe and the trumpet pipe in a radial direction perpendicular to the central axis, and a second insulated material disposed on the axial end side of the trumpet pipe.

4. The gas flow pipe, wherein the gas flow pipe does not have a refrigerant flow path in the peripheral wall of the gas flow pipe, according to any one of claims 1 to 3.

5. The inlet pipe according to any one of claims 1 to 3, wherein, in a cross-sectional view along the central axis, the angle formed between the tapered portion and the central axis is 20 degrees or more and 50 degrees or less.

6. The inlet pipe according to any one of claims 1 to 3, wherein the tapered portion extends in a curved manner in a cross-sectional view along the central axis.

7. The blowpipe according to any one of claims 1 to 3, wherein the axial dimension of the trumpet-shaped pipe is 100 mm or more and 500 mm or less.

8. The blowpipe according to any one of claims 1 to 3, wherein the flared pipe has a tapered portion and a base end cylindrical portion connected to the axial base end of the tapered portion and joined to the flange.

9. The inlet pipe according to any one of claims 1 to 3, wherein the trumpet pipe further has a tip cylindrical portion connected to the axial tip end of the tapered portion and joined to the gas flow pipe.

10. The blowing pipe according to any one of claims 1 to 3, wherein the flange has a refrigerant flow path.

11. The blowing pipe according to any one of claims 1 to 3, wherein when the blowing pipe is viewed in a longitudinal section along the central axis, the blowing opening is oriented diagonally downward.

12. A gas flow path structure comprising: an inlet pipe according to any one of claims 1 to 3; and a branch pipe connected to the inlet pipe from the axial base end side, wherein the branch pipe has: an outer cylinder joined to the flange; a gas supply passage inserted inside the outer cylinder and connected to the gas flow pipe; and a heat insulating portion disposed between the outer cylinder and the gas supply passage, wherein the outer cylinder has an outer tapered portion that decreases in diameter towards the axial tip side, and the maximum diameter dimension of the outer tapered portion is greater than the maximum diameter dimension of the tapered portion.

13. A blowing structure comprising a staves positioned on the furnace wall of the shaft or belly section of a blast furnace, and a blowing pipe according to any one of claims 1 to 3.

14. The blowing structure according to claim 13, wherein the stave has a plate portion and a projection portion that protrudes from the plate portion toward the core.

15. The blowing structure according to claim 14, wherein the stave penetrates the plate portion and has an opening located below the protruding portion, and the blowing pipe is located within the opening.

16. A blowing structure comprising a stave positioned on the furnace wall of the shaft or belly section of a blast furnace, and a blowing pipe according to any one of claims 1 to 3, 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 radial direction of the furnace.

17. The blowing structure according to claim 16, 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.

18. The blowing structure according to claim 16, wherein when the blowing pipe is viewed in a longitudinal section along the central axis, the blowing opening is oriented diagonally downward.

19. A blowing structure comprising a furnace wall of the shaft or belly section of a blast furnace, and a blowing pipe according to any one of claims 1 to 3, wherein the gas flow pipe does not have a refrigerant flow path in its circumferential wall, and the axial tip of the blowing opening is positioned in a range of 5 mm to 20 mm from the inner surface of the furnace wall toward the axial base end.

20. A blowing structure comprising: a stave disposed on the furnace wall of the shaft or belly section of a blast furnace; and a blowing pipe according to any one of claims 1 to 3, wherein the gas flow pipe does not have a refrigerant flow path on its peripheral wall; and the stave has an opening that penetrates the plate section of the stave and in which the blowing pipe is disposed; and a hardened build-up disposed on the inner surface of the plate section around the opening.

21. A blowing structure comprising: an outer wall of the shaft or belly section of a blast furnace; and a blowing pipe according to any one of claims 1 to 3, wherein the outer wall has a steel shell and a mounting cylinder fixed to the steel shell, and the flange is supported by the mounting cylinder.

22. A blowing structure comprising a furnace wall of the shaft or belly section of a blast furnace, and a blowing pipe according to any one of claims 1 to 3, wherein two or more blowing pipe insertion openings are formed in the furnace wall and 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 openings.

23. A blowing structure comprising: a stave disposed on the furnace wall of the shaft or belly section of a blast furnace; and a blowing pipe according to any one of claims 1 to 3, wherein a blowing pipe insertion port is formed in the stave through which the blowing pipe is inserted, and the blowing pipe insertion port is located on the periphery of the stave.

24. The blowing pipe insertion port is located at the corner of the periphery of the stave, the blowing structure according to claim 23.

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