Double-walled lance for injecting reducing agent and oxygen into the blast furnace through the tuyeres.
The double-walled lance with optimized inner and outer tube configurations addresses the inefficiencies in TGR-BF mode by enhancing gas orbits and temperature control, ensuring effective combustion and reducing particle accumulation in blast furnaces.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ARCELORMITTAL SA
- Filing Date
- 2023-06-29
- Publication Date
- 2026-07-10
Smart Images
Figure 2026523111000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a double-wall lance for injecting a reducing agent and oxygen through tuyeres, and a method for injecting high-temperature reducing gas into a blast furnace through tuyeres.
[0002] In a blast furnace, since it usually has a temperature exceeding 900°C, blowing air, also called hot air, is injected into the blast furnace through tuyeres. Before this injection, the blast furnace is charged with raw materials necessary for pig iron products such as coke, semi-coke, pellets, iron ore, and sintered iron. Coke is charged into the blast furnace as the main reducing agent. The iron charge gradually becomes hot and is reduced to iron in the shaft of the furnace. This finally becomes soft and is melted at the lower part of the furnace, forming a so-called cohesive zone there. Below this level, coke is the only solid material remaining in the lower part of the furnace (coke storage zone) and the hearth of the blast furnace. Pulverized coal (PC) is generally considered as the main auxiliary reducing agent. This is injected into the blast furnace thanks to a sub-lance introduced into the tuyere. When the blowing air is injected into the coke storage zone together with PC particles, a cavity zone called a trajectory is generated in front of the tuyere due to the partial combustion of the reducing agent and the oxygen in the blowing air. The size of this cavity is related to several parameters, among which is related to the impact of gas injection at the outlet of the tuyere. This impact can be expressed as I(N)=Qm(kg / s)xV(m / s), where I is the impact, Qm is the mass flow rate of the gas exiting the tuyere, and V is the velocity of the gas. In the standard method of operating a blast furnace, this impact is about 7 N.
Background Art
[0003] It should be noted that there seems to be an error in the text you provided. In the original text, the impact formula calculation result in the English translation should be about 700N according to the original text, not 7N. The above translation has been corrected according to the correct data. If you have any other questions, please feel free to let me know.For the past several decades, efforts have been made to reduce carbon dioxide emissions at the blast furnace level. One solution developed, described in International Publication No. 2010 / 106387, is a top gas regenerating blast furnace (TGRBF), which involves processing the exhaust gas from the blast furnace and reinjecting at least some of the reducing gas produced in the blast furnace through a classic tuyeres located at the top of the furnace hearth. In the now-preferred type of this new type of operation, compared to the "classic" operation of the blast furnace, the difference is that all the hot air is replaced with regenerating reducing gas. However, in this configuration, the specific consumption of regenerating reducing gas is much lower than the specific consumption of hot air in the classic operation, and in some cases, the temperature is also lower. This results in a much lower gas flow rate at the tuyeres outlet compared to the classic hot air operation, especially in response to impulse trains of less than 300 N.
[0004] As a result, injection into the blast furnace creates smaller orbits. Orbit size is important because it affects the gas distribution in the lower part of the furnace, and the heat load on the furnace walls can become a significant problem in this high-temperature range of the furnace. This also affects the efficiency of partial combustion of reducing agents such as pulverized coal injected through tuyeres, as unburned particles can accumulate in the lower part of the furnace, potentially hindering their permeability. Melting conditions at the fusion zone level can also have an impact. [Overview of the project] [Problems that the invention aims to solve]
[0005] Next, when the blast furnace is operating in TGR-BF mode, while protecting the sublance material from unacceptably high temperatures, a device is needed that can increase the size of the orbits created when the high-temperature reducing gas is injected through a normal tuyeres. [Means for solving the problem]
[0006] This problem is, a. An inner tube for injecting a reducing agent, b. An outer tube for injecting oxygen, surrounding the inner tube, c. An end positioned at the exit of the lance within the tuyer, the end of which closes the lance. - Front, having a diameter D, i. The front surface includes a reducing agent outlet hole located on the front surface of the inner tube, allowing the reducing agent to be released. - A front peripheral portion including a cap having a number of main oxygen outlet holes located on the front surface of the outer tube to allow oxygen to escape, and an annular wall surrounding the open end and extending over a length L from the front surface of the end to the free edge. Ends having Includes, The length L of the cap ends (12a, 12b, 12c) is greater than 21.3% of the diameter D of the front surface (11a, 11b, 11c), which is resolved by the double-walled lance of the present invention.
[0007] The lance of the present invention may also include the following optional characteristics, either separately conceived or by any combination of all possible technologies: - The cap extends over a length L exceeding 12 mm from the front edge to the free edge. - The cap extends over a length L of at least 13 mm from the front edge to the free edge. - The total surface area of the main oxygen outlet holes is at least 30% of the surface area of the front peripheral edge of the front surface of the end of the lance. - The inner tube walls are made from solid material. - The main oxygen outlet holes are spaced apart along the front periphery. - There are at least 7 main oxygen outlet vents. - The main oxygen outlet vent has a trapezoidal shape. - The front peripheral portion further includes secondary oxygen outlet holes located between the main oxygen outlet holes, centered on the peripheral portion of the front peripheral portion. - The total surface area of the secondary oxygen outlet holes is at most 10% of the surface area of the front edge of the front surface of the lance end. - The reducing agent outlet hole is located in the same cross-section as the free edge of the cap, or extends beyond the free edge of the cap. - According to a preferred embodiment of the present invention, i. The front peripheral edge is positioned perpendicular to the annular wall of the cap. ii. The reducing agent outlet hole extends beyond the free edge of the cap. iii. The front periphery includes seven main oxygen outlet holes. iv. The secondary oxygen outlet port has a stadium shape. Alternatively, the front peripheral edge is positioned to converge toward the open end of the cap, and the reducing agent outlet hole is located in the same cross-section as the free edge of the cap. - According to another preferred embodiment of the present invention, which includes such a convergent arrangement, the front periphery includes eight main oxygen outlet holes, and the secondary oxygen outlet holes have a circular shape. - According to another preferred embodiment of the present invention, which also includes such a concentrated arrangement, the front periphery includes seven main oxygen outlet holes, and the secondary oxygen outlet holes have a stadium shape.
[0008] The present invention also relates to a method for injecting high-temperature reducing gas into a blast furnace through a tuyer, and the said method is a. Injecting high-temperature reducing gas into the tuyeres, b. Injecting a reducing agent into the inner tube of the double-walled lance as described above, wherein the double-walled lance is inserted into the tuyere, and the injection is performed. c. Injecting oxygen-carrying gas into the outer tube of the double-walled lance, d. The oxygen-carrying gas is brought into contact with the reducing agent before being injected into the blast furnace. Includes.
[0009] Preferably, the high-temperature reducing gas includes the regenerating furnace top gas of a blast furnace.
[0010] Other features and advantages of the present invention are given below for illustrative purposes and will become apparent from the accompanying drawings, as well as from the description, which is not limiting. [Brief explanation of the drawing]
[0011] [Figure 1] This is a general cross-sectional view of the double-walled lance of the present invention placed inside a tuyer. [Figure 2]Perspective view of the end of the first embodiment of the double-wall lance of the present invention. [Figure 3] Front view of the end of the double-wall lance of FIG. 2. [Figure 4] Illustrates the trajectory of coal particles inside the tuyere when using the double-wall lance of FIG. 2. [Figure 5] Perspective view of the end of the second embodiment of the double-wall lance of the present invention. [Figure 6] Front view of the end of the double-wall lance of FIG. 5. [Figure 7] Cross-sectional view of the end of the double-wall lance of FIG. 5. [Figure 8] Illustrates the trajectory of coal particles inside the tuyere when using the double-wall lance of FIG. 5. [Figure 9] Perspective view of the end of the third embodiment of the double-wall lance of the present invention. [Figure 10] Front view of the end of the double-wall lance of FIG. 9. [Figure 11] Illustrates the trajectory of coal particles inside the tuyere when using the double-wall lance of FIG. 9.
Mode for Carrying Out the Invention
[0012] The elements in the figures are illustrative and may not be drawn to a fixed scale.
[0013] Referring to FIG. 1, the lance 1 of the present invention is obliquely introduced into the tuyere 4, which has an end 16 and an outlet hole 17 so that high-temperature gas can be injected into the blast furnace. The end 7 of the lance 1 is placed inside the end 16 of the tuyere 4 upstream of the outlet hole 17. The high-temperature gas 18 flowing through the tuyere 6 has a temperature of 700 to 1300°C and can be regenerated top gas. This regenerated gas preferentially contains more than 70%, more preferably more than 80%, and ideally more than 90% of the CO / H2 mixture. The CO2 / H2O mixture is limited to less than 5%, preferably less than 3%, and the rest is mainly nitrogen N2.
[0014] The lance 1 of the present invention includes an inner tube 5 for a reducing agent, and an outer tube 6 that surrounds the inner tube 5 and thus defines an annular tube through which oxygen flows. The reducing agent may be natural gas, carbonized gas, fuel oil, or pulverized coal. Preferably, the reducing agent is pulverized coal. The axis of the end 7 of the double-walled lance 1 is slightly inclined along the longitudinal axis XX' of the tuyeres 4 to inject the reducing agent 2 and oxygen 3 into the high-temperature gas 18.
[0015] The exothermic combustion reaction between the reducing agent and oxygen occurs near the outlet of lance 1 due to the injection of oxygen, which increases the impact force of the gas injection at the outlet 17 of tuyeres 4. The frame temperature can reach nearly 3000°C in some places, but if the temperature exceeds 1100°C at the end 7 of lance 1, it can cause irreparable damage to lance 1.
[0016] According to the present invention, the end 7 of the lance 1 has a diameter D and includes a front surface containing a reducing agent outlet hole, and a front peripheral portion containing a plurality of main oxygen outlet holes surrounding the reducing agent outlet hole. In such a combination of oxygen outlet hole arrangements, the end 7 of the lance 1 includes a cap that surrounds the end 7 and extends from the front surface of the end over a length L. According to the present invention, the length L of the cap may exceed 21.3% of the diameter D of the front surface. Preferably, the length L is greater than 12 mm, and more preferably at least 13 mm. It has been found that such a minimum length of the cap makes it possible to avoid high temperature points exceeding 1100°C at the end 7 of the lance 1.
[0017] The minimum length of the cap must be determined by considering the placement and surface of the oxygen outlet holes, as these directly contribute to combustion and therefore directly contribute to the rise in temperature near the lance, while increasing the length of the cap decreases the temperature near the lance.
[0018] Conveniently, the total surface area of the main oxygen outlet holes is at least 30% of the surface area of the front peripheral edge, so that the end of the lance can inject the amount of oxygen necessary to obtain an acceptable combustion force. Preferably, the total surface area of the main oxygen outlet holes is 60% or less of the surface area of the front peripheral edge.
[0019] More conveniently, the front periphery further includes a plurality of secondary oxygen outlet holes positioned between the main oxygen outlet holes. Preferably, the total surface area of the secondary oxygen outlet holes is 10% or less of the surface area of the front periphery of the front surface of the end of the lance, and more preferably, it is included in 3-10% of the surface area of the front periphery.
[0020] Conveniently, the edges of the cap are rounded to avoid the formation of thermal solidification points.
[0021] To place combustion near the outlet of lance 1, the walls of inner tube 5 are constructed from a solid material to avoid any obstacles along inner tube 5.
[0022] Furthermore, in order to uniformly distribute the oxygen flow gas within the tuyere, the main oxygen outlet holes are spaced apart along the periphery of the front surface. Such arrangement results in a homogeneous temperature distribution within the tuyere 4. While the main oxygen outlet holes can be uniformly spaced along the periphery of the front surface, it is preferable for the main oxygen outlet holes to be irregularly spaced along the periphery of the front surface to avoid interference caused by vibration.
[0023] To optimize contact between oxygen and reducing gas downstream of the lance tip, and therefore to optimize the combustion of the reducing gas, there are at least seven main oxygen outlet holes. In the examples described later, the front periphery includes seven or eight main oxygen outlet holes.
[0024] The shape of the main oxygen outlet is also defined to optimize the combustion reaction and maintain the combustion force at an acceptable level. For this purpose, the main oxygen outlet has a trapezoidal shape, with its greatest width occurring on the side of the annular wall of the cap.
[0025] In the context of the present invention, it has been found that the addition of secondary oxygen outlets placed between the main oxygen outlets limits the recirculation of gases (especially CO) inside the cap, and therefore further reduces the temperature and high-temperature points at the end 7 of the lance 1. For this purpose, the total surface area of the secondary oxygen outlets is 3-10% of the surface area of the front surface. The secondary oxygen outlets can have a circular or stadium shape. The shape of the secondary oxygen outlets must be adjusted according to other structural parameters of the lance.
[0026] Another technical feature of the lance of the present invention is the relative position of the reducing agent outlet hole and the free edge of the cap. In this regard, it has been found that in order to avoid the recirculation of coal particles within the cap, the reducing agent outlet hole should be in the same cross-section as the free edge of the cap, or should extend beyond the free edge of the cap.
[0027] The shape of the front peripheral portion through which oxygen is injected can be adjusted to optimize the efficiency of injection through the tuyeres. For this purpose, the front peripheral portion can be perpendicular to the annular wall of the cap or can be positioned convergently toward the open end of the cap. In both configurations, the relative position between the reducing agent outlet hole and the free edge of the cap is adjusted according to the selected shape choice.
[0028] The present invention also relates to a method for injecting high-temperature reducing gas into a blast furnace through a tuyer using the double lance described above. The method consists of the following steps: - Injecting high-temperature reducing gas into the tuyeres, - Injecting a reducing agent into the inner tube of a double-walled lance inserted into the tuyeres, - Injecting oxygen-carrying gas into the outer tube of a double-walled lance, - This includes contacting the oxygen-carrying gas with a reducing agent before injecting it into the blast furnace.
[0029] Conveniently, high-temperature reducing gases include the regenerative top gas of blast furnaces for environmental reasons.
[0030] Three preferred embodiments of the lance 1 according to the present invention are described below.
[0031] In the first embodiment of the lance of the present invention illustrated in Figures 2 to 4, the end 7a of the double-walled lance 1a has a front surface 11a having a diameter D of 56.5 mm and including a circular reducing agent outlet hole 8a that forms the free end of the inner tube 5. The circular reducing agent outlet hole 8a is surrounded by a front surface periphery 9a positioned between the inner tube 5 and the outer tube 6. The end 7a of the lance 1a is slightly inclined to inject the reducing agent 2 and oxygen 3 into the gas 18 along the longitudinal axis XX' of the tuyere 4 (Figure 1).
[0032] The end 7a further includes a cap 12a made from the annular wall 13a, which is substantially a cut cone shape. The cap 12a extends from the front 11a to a circular free edge 14a. The cap has a length of 16 millimeters, such that the length of the cap is 28.3% of the diameter of the front.
[0033] The front peripheral portion 9a is positioned perpendicular to the annular wall 13a of the cap and includes seven trapezoidal main oxygen outlet holes 10a that are uniformly spaced along the front peripheral portion 9a, with the widest width being on the side surface of the annular wall 13a of the cap 12a. The total surface area of the seven main oxygen outlet holes 10a is approximately 36% of the surface area of the front peripheral portion 9a of the front surface 11a of the end 7a of the lance 1a.
[0034] The front peripheral portion 9a further includes seven secondary oxygen outlet holes 15a, each positioned between two adjacent primary oxygen outlet holes 10a on the side surface of the annular wall 13a of the cap 12a. Each secondary oxygen outlet hole 15a has a stadium shape. The total surface area of the secondary oxygen outlet holes 15a is approximately 6% of the surface area of the front peripheral portion 9a of the front surface 11a of the end 7a of the lance 1a.
[0035] The reducing agent outlet hole 8a extends beyond the front peripheral edge 9a and also beyond the free end edge 14a of the cap 12a. The outer extension of the inner tube 5 is 20 mm, so that the reducing agent outlet hole 8a extends beyond the 4 mm free end edge 14a of the cap 12a.
[0036] Thanks to this configuration, the maximum temperature at the end 7a of lance 1a is 1030°C, and the impact force of the gas flow at the tuyer's outlet is 384N.
[0037] Referring to Figure 4, the coal particles 2 are not sucked into the cap 12a, nor do they collide with the inner wall of the tuyere 4; instead, they are discharged from the tuyere 4.
[0038] In a second embodiment of the lance according to the present invention illustrated in Figures 5 to 8, the end 7b of the double-walled lance 1b has a front surface 11b having a diameter D of 56.5 mm and including a circular reducing agent outlet hole 8b that forms the free end of the inner tube 5. The circular reducing agent outlet hole 8b is surrounded by a front surface periphery 9b positioned between the inner tube 5 and the outer tube 6. As shown in Figure 7, the end 7b of the lance 1b is slightly inclined to inject the reducing agent 2 and oxygen 3 into the gas 18 along the longitudinal axis XX' of the tuyere 4 (Figure 1).
[0039] The end 7b further includes a cap 12b made from an annular wall 13a which is slightly truncated in shape (Figure 7). The cap 12b extends from the front surface 11b to a circular free edge 14b. The cap 12b has a length L of 16 millimeters, such that the length of the cap is 28.3% of the diameter D of the front surface.
[0040] The front peripheral portion 9b is positioned to converge toward the open end of the cap 12b, up to the free end edge 14b of the cap 12b, so that the reducing agent outlet hole 8b is in the same cross-section as the free end edge 14b of the cap 12b (Figure 7). The convergence angle is 28°.
[0041] The front peripheral portion 9b includes eight trapezoidal main oxygen outlet holes 10b that are irregularly spaced along the front peripheral portion 9b, with the widest width being on the side surface of the annular wall 13b of the cap 12b. The total surface area of the eight main oxygen outlet holes 10b is approximately 36% of the surface area of the front surface 11b of the end 7b of the lance 1b.
[0042] The front peripheral portion 9b further includes secondary oxygen outlet holes 15b positioned between the main oxygen outlet holes 10b. Each secondary oxygen outlet hole 15b has a circular shape. One, two, or three secondary oxygen outlet holes 15b are positioned between two adjacent main oxygen outlet holes 10b on the side surface of the annular wall 13b of the cap 12b, resulting in an irregular arrangement of the main oxygen outlet holes 10b.
[0043] The total surface area of the secondary oxygen outlet hole 15b is approximately 6% of the surface area of the front peripheral edge 9b of the front surface 11b of the end 7b of the lance 1b.
[0044] Thanks to this configuration, the maximum temperature at the end 7b of lance 1b is less than 1100°C, and the impact force is 366N.
[0045] Referring to Figure 8, the coal particles 2 are not sucked into the cap 12b and are discharged from the tuyere 4 without hitting the inner wall of the tuyere 4.
[0046] In a third embodiment of the lance according to the present invention illustrated in Figures 9 to 11, the end 7c of the double-walled lance 1c has a front surface 11c having a diameter D of 56.5 mm and including a circular reducing agent outlet hole 8c that forms the free end of the inner tube 5. The circular reducing agent outlet hole 8c is surrounded by a front surface periphery 9c positioned between the inner tube 5 and the outer tube 6. As in the first and second embodiments, the end 7c of the lance 1c is slightly inclined.
[0047] The end 7c further includes a cap 12c made from an annular wall 13c which is slightly cut cone-shaped. The cap 12c extends from the front 11c to a circular free edge 14c. The cap 12c has a length L of 16 millimeters, such that the length of the cap is 28.3% of the diameter D of the front.
[0048] The front peripheral portion 9c is positioned to converge toward the open end of the cap 12c, up to the free end edge 14c of the cap 12c, so that the reducing agent outlet hole 8b is located in the same cross-section as the free end edge 14c of the cap 12c. The convergence angle is 42°.
[0049] The front peripheral portion 9c includes seven trapezoidal main oxygen outlet holes 10c that are uniformly spaced along the front peripheral portion 9c, and the widest part of the cap is on the side of the annular wall 13c of the cap 12c.
[0050] The front peripheral portion 9c further includes seven secondary oxygen outlet holes 15c, each positioned between two adjacent primary oxygen outlet holes 10c on the side surface of the annular wall 13c of the cap 12c. Each secondary oxygen outlet hole 15c has a stadium shape.
[0051] In this embodiment, the surface area of each main oxygen outlet hole 10c is 87.94 mm². 2 The surface area of each secondary oxygen outlet hole 15c is 14.57 mm². 2 Therefore, the total surface area of the seven main oxygen outlet holes 10c is 36.45% of the surface area of the front peripheral edge 9c, which has a total surface area of 1688.80 mm2, and the total surface area of the seven secondary oxygen outlet holes 15c is 6.04% of the surface area of the front peripheral edge 9c. The total surface area of the main oxygen outlet holes 10c and secondary oxygen outlet holes 15c is therefore 42.09% of the surface area of the front peripheral edge 9c.
[0052] Thanks to this configuration, the maximum temperature at the end 7b of lance 1b is less than 1100°C, and the impact force is 366N.
[0053] Referring to Figure 11, the coal particles 2 are not sucked into the cap 12c and are discharged from the tuyere 4 without hitting the inner wall of the tuyere 4.
[0054] Next, we will describe comparative examples that demonstrate the effects of the features of the lance of the present invention.
[0055] Tables 1 and 2 show the results obtained with the lance according to the present invention compared with lances outside the scope of the present invention.
[0056] The three results are shown in these tables (the last three columns), namely, the impact force expressed in Newtons, the orbital path of the reducing agent particles within the tuyer, and the presence or absence of a high-temperature point at the end of the lance.
[0057] For reducing agent particle orbitals, the symbol "--" indicates that the coal particle strikes the inner wall of the tuyere, while the symbol "++" indicates that the coal particle does not strike the inner wall of the tuyere. The symbol "+" means that the particle orbit is acceptable.
[0058] Regarding the high-temperature point at the end of the lance, the symbol "--" means that the temperature at the end of the lance exceeds 1100°C and is unacceptable, while the symbol "++" means that the temperature at the end of the lance is below 1100°C. The symbol "+" means that the temperature at the end of the lance is within the acceptable range at approximately 1100°C, but is below 1100°C.
[0059] In Table 1, Examples A to E correspond to lances not according to the present invention. In Tables 1 and 2, Examples 1 to 7 correspond to lances according to the present invention. Each of Examples 1 to 3 corresponds to Embodiments 1 to 3 described earlier with reference to Figures 2 to 11. In all Examples A to E and 1 to 7, the front diameter is 56.5 mm.
[0060] According to Table 1, when the cap length is 12 mm (21.3% of the front diameter), the temperature at the end of the lance is unacceptable for a cap length of 13 mm (23.0% of the front diameter), but the temperature is within the acceptable range at approximately 1100°C. Therefore, the cap length must exceed 21.3% of the front diameter, and thus must exceed 12 mm, and more preferably at least 13 mm.
[0061] Table 1 illustrates the effect of the presence of the cap and the effect of the cap length. To reach the permissible temperature at the end of the lance, the cap length must be at least 23% of the front diameter. In these examples, the cap length must be at least 13 millimeters. A length of 16 millimeters is preferable to reach temperatures below 1100°C (according to Examples 1-3).
[0062] Table 2 illustrates the results obtained for four examples of the lance according to the present invention, where the front periphery is perpendicular to the wall of the cap. Example 1, described earlier with reference to Figures 2-4, gives the best result.
[0063] [Table 1]
[0064] [Table 2] [Prior art documents] [Patent Documents]
[0065] [Patent Document 1] International Publication No. 2010 / 106387
Claims
1. A double-walled lance (1) for injecting a reducing agent (2) and oxygen (3) through the tuyer (4) of a blast furnace, wherein the lances (1, 1a, 1b, 1c) are a. An inner tube (5) for injecting the reducing agent (2), b. An outer tube (6) for injecting oxygen (3) surrounding the inner tube (5), c. Ends (7, 7a, 7b, 7c) placed within the tuyere (4) at the end of the lance (1), wherein the ends (7, 7a, 7b, 7c) close the lance (1), - Front surface (11a, 11b, 11c) having a diameter D, i. Reducing agent outlet holes (8a, 8b, 8c) are placed on the front surface of the inner tube (5) so that the reducing agent (2) can be dispensed, ii. Front peripheral portion (9a, 9b, 9c) including a plurality of main oxygen outlet holes (10a, 10b, 10c) placed on the front surface of the outer tube (6) so that oxygen (3) can be released. Including the front surface (11a, 11b, 11c), - Cap (12a, 12b, 12c) having an annular wall (13a, 13b, 13c) that surrounds the open end and the end (7, 7a, 7b, 7c) and extends over a length L from the front surface (11a, 11b, 11c) of the end (7, 7a, 7b, 7c) to the free end edge (14a, 14b, 14c) and The ends (7, 7a, 7b, 7c) have Includes, The length L of the cap (12a, 12b, 12c) is greater than 21.3% of the diameter D of the front surface (11a, 11b, 11c), thus forming a lance.
2. The lance according to claim 1, wherein the caps (12a, 12b, 12c) extend over a length L exceeding 12 mm from the front surface (11a, 11b, 11c) of the end portion (7, 7a, 7b, 7c) to the free end edge (14a, 14b, 14c).
3. The lance according to claim 1 or 2, wherein the caps (12a, 12b, 12c) extend over a length L of at least 13 mm from the front surface (11a, 11b, 11c) of the end portion (7, 7a, 7b, 7c) to the free end edge (14a, 14b, 14c).
4. The lance according to claim 1 or 2, wherein the total surface area of the main oxygen outlet holes (10a, 10b, 10c) is at least 30% of the surface area of the front peripheral portion (9a, 9b, 9c) of the front surface (11a, 11b, 11c) of the end portion (7, 7a, 7b, 7c) of the lance (1, 1a, 1b, 1c).
5. The lance according to any one of claims 1 to 4, wherein the wall of the inner tube (5) is made of a solid material.
6. The lance according to any one of claims 1 to 5, wherein the main oxygen outlet holes (10a, 10b, 10c) are spaced apart along the front peripheral edges (9a, 9b, 9c).
7. The lance according to any one of claims 1 to 6, wherein the main oxygen outlet holes (10a, 10b, 10c) are at least seven.
8. The lance according to any one of claims 1 to 7, wherein the main oxygen outlet holes (10a, 10b, 10c) have a trapezoidal shape.
9. The lance according to any one of claims 1 to 8, wherein the front peripheral portion (9a, 9b, 9c) further includes secondary oxygen outlet holes (15a, 15b, 15c) positioned between the main oxygen outlet holes (10a, 10b, 10c) centered on the peripheral portion of the front peripheral portion (9a, 9b, 9c).
10. The lance according to claim 9, wherein the total surface area of the secondary oxygen outlet holes (15a, 15b, 15c) is at most 10% of the surface area of the front peripheral edges (9a, 9b, 9c) of the front surfaces (11a, 11b, 11c) of the ends (7, 7a, 7b, 7c) of the lance (1, 1a, 1b, 1c).
11. The lance according to claim 10, wherein the reducing agent outlet holes (8a, 8b, 8c) are located in the same cross-section as the free edges (14a, 14b, 14c) of the cap (12a, 12b, 12c), or extend beyond the free edges (14a, 14b, 14c) of the cap (12a, 12b, 12c).
12. - The front peripheral portion (9a) is positioned perpendicular to the annular wall (13a) of the cap (12a), - The reducing agent outlet hole (8a) extends beyond the free edge (14a) of the cap (12a), - The front peripheral portion (9a) includes seven main oxygen outlet holes (10a), - The secondary oxygen outlet port (15a) has a stadium shape. The lance according to claim 11.
13. The lance according to claim 11, wherein the front peripheral edges (9b, 9c) are arranged to converge toward the open end of the cap (12b, 12c), and the reducing agent outlet holes (8b, 8c) are located in the same cross-section as the free end edges (14b, 14c) of the cap (12b, 12c).
14. The lance according to claim 13, wherein the front peripheral portion (9b) includes eight main oxygen outlet holes (10b), and the secondary oxygen outlet holes (15b) have a circular shape.
15. The lance according to claim 13, wherein the front peripheral portion (9c) includes seven main oxygen outlet holes (10c), and the secondary oxygen outlet holes (15c) have a stadium shape.
16. A method of injecting a high-temperature reducing agent into a blast furnace through a tuyeres (4), a. Injecting high-temperature reducing gas into the tuyeres (4), b. Injecting a reducing agent (2) into the inner tube (5) of the double-walled lance (1, 1a, 1b, 1c) described in any one of claims 1 to 15, wherein the double-walled lance (1, 1a, 1b, 1c) is inserted into the tuyere (4), and the injection is performed. c. Injecting oxygen transport gas (3) into the outer tube (6) of the double-walled lance (1, 1a, 1b, 1c), d. Before injecting it into the blast furnace, the oxygen carrier gas (3) is brought into contact with the reducing agent (2). Methods that include...
17. The method according to claim 16, wherein the high-temperature reducing gas includes the regenerating furnace top gas of the blast furnace.