Injection nozzle and method for operating a metallurgical furnace

Abstract

The invention relates to an injection nozzle (1) and a method for operating a metallurgical furnace.

Description

[0001] The invention relates to an injection nozzle and a method for operating a metallurgical furnace.

[0002] Introducing gaseous media into metallurgical processes is common practice. These gaseous media are typically introduced via injection nozzles. Depending on the application and environment, cooling of the injection nozzle or nozzle tip may be necessary, particularly to reduce wear and thus prevent premature failure. When using, for example, oxygen, which can be injected through nozzles, very high temperatures can occur, especially at the nozzle tips, such as those found on tuyeres in blast furnaces. As a result, existing water-cooled systems, especially those with closed cooling circuits, can fail rapidly after a certain temperature and duration.

[0003] The object of the present invention is to provide a thermally resistant injection nozzle compared to the prior art, as well as a corresponding method for operating a metallurgical furnace.

[0004] This problem is solved by an injection nozzle with the features of claim 1 and by a method with the features of claim 3. Further embodiments are listed in the dependent claims.

[0005] The first teaching of the invention relates to an injection nozzle with an injection channel extending centrally within the injection nozzle for injecting gaseous media, a cooling channel arranged radially to the injection channel and extending within the injection nozzle, in particular substantially parallel to the injection channel, for conveying a first cooling medium, and a wall separating the injection channel and the cooling channel, wherein at least one opening or several openings distributed around the circumference of the wall are arranged in the wall, through which a second cooling medium can be conveyed and thus introduced into the injection channel.

[0006] The second teaching of the invention relates to a method for operating a metallurgical furnace, wherein the metallurgical furnace comprises at least one injection nozzle, the injection nozzle having an injection channel for injecting gaseous media, which extends centrally within the injection nozzle, a cooling channel arranged radially to the injection channel and extending within the injection nozzle, in particular substantially parallel to the injection channel, for conveying a first cooling medium, and a wall arranged between the injection channel and the cooling channel, wherein the wall has at least one opening or several openings distributed around the circumference of the wall, through which a second cooling medium is conveyed during operation of the injection nozzle and thus introduced into the injection channel.

[0007] The inventors have discovered that by providing at least one opening in the wall, or several openings distributed around the circumference of the wall, which separate the injection channel from the cooling channel and thereby allow a second cooling medium to be passed through the opening(s) and introduced into the injection channel, the thermal wear of the injection nozzle can be positively influenced, particularly when hot gaseous media are passed through the injection channel, which can have temperatures of, for example, at least 500 °C, 600 °C, in particular at least 700 °C, 800 °C, preferably at least 900 °C, 1000 °C. The temperature of the gases can be up to 2000 °C, in particular up to 1800 °C, preferably up to 1500 °C, preferably up to 1300 °C.

[0008] The second cooling medium can be a component of the first cooling medium, in which case a portion of the first cooling medium can be passed through the opening(s) from the cooling channel as the second cooling medium. Preferably, the second cooling medium is isolated from the first cooling medium and differs from it, particularly in its state of matter. The first cooling medium is preferably a liquid, and the second cooling medium is most preferably a gas.

[0009] The cooling channel can also include several cooling channels arranged around the circumference of the injection channel, in particular side by side.

[0010] According to a preferred embodiment, the opening or openings have an angled extension in the wall. In the context of the invention, this means that, in a longitudinal section through the injection nozzle, the opening(s) extend at an angle between 20° and 80° to a vertical. This allows the second cooling medium to be introduced in the flow direction of the gaseous medium and thus prevents it from significantly and negatively affecting the momentum of the gaseous medium.

[0011] According to a preferred embodiment, the second cooling medium exiting the opening(s) can be captured by the gaseous medium and adhere to the inner surface of the injection channel as a flow film. As a result, there is no longer any direct contact between the preferably hot gaseous medium and the inner surface of the injection channel or its wall in the area of ​​the generated flow film. This allows the injection nozzle to be provided in a more thermally stable and / or thermally resistant manner compared to prior art designs (without opening(s) in the wall), and ensures a longer service life for the operation of a metallurgical furnace comprising at least one injection nozzle according to the invention.

[0012] If, for example, the second cooling medium is a component of the first cooling medium, then at least 2%, 3%, 4%, in particular at least 5%, 6%, 7%, and in particular a maximum of 30%, 25%, 20%, preferably 15%, 12%, or 10% of the first cooling medium introduced into the injection nozzle for cooling the injection nozzle can be introduced through the opening(s) into the injection channel and thus discharged from the cooling system. The discharged portion of the cooling medium can be specified in wt.% or preferably in vol.%. The quantity or volume discharged from the cooling system can be fed back into the cooling system, whereby the remaining cooling medium in the cooling system can, for example, be circulated using means known to those skilled in the art. Water can be used as the liquid for the first cooling medium.

[0013] According to a particularly preferred embodiment, a blast furnace can be used as the metallurgical furnace. The blast furnace comprises at least one injection nozzle through which hot gaseous media, such as the so-called and well-known hot blast, are (or must be) introduced into the blast furnace. The injection nozzle can thus be part of the tuyeres installed on the blast furnace for introducing the hot blast.

[0014] According to one embodiment, a liquid cooling medium can be used. When a portion of the liquid cooling medium is introduced into the injection channel and comes into contact with a hot gaseous medium flowing through the injection channel, the introduced liquid can evaporate, which can have a beneficial effect on heat dissipation. For example, water can be used as a second cooling medium, which has the advantage that, upon contact with hot gaseous media, it decomposes into water vapor or even into hydrogen and oxygen. The hydrogen can, for example, act as a reducing agent in a metallurgical furnace, preferably a blast furnace, and the oxygen can be used for afterburning and thus to increase the heat in the metallurgical furnace, preferably a blast furnace.The use of liquid hydrocarbons is also conceivable, which can evaporate and / or be cracked by contact and / or reaction with a hot gaseous medium in order to function as reducing agents.

[0015] According to a preferred embodiment, a gas such as carbon monoxide, carbon dioxide, nitrogen, argon, water vapor, hydrogen, hydrocarbon (such as natural gas), coke oven gas, blast furnace gas, air or mixtures thereof can be used as the second cooling medium.

[0016] The invention is explained in more detail with reference to the following exemplary embodiments in conjunction with the Figure 1 .

[0017] An exemplary injection nozzle (1) according to the invention is shown in a schematic longitudinal section in Figure 1The injection nozzle (1) comprises an injection channel (5) extending centrally within the injection nozzle (1) for injecting gaseous media (5.1), a cooling channel (4) arranged radially to the injection channel (5) and extending substantially parallel to the injection channel (5) within the injection nozzle (1) for conveying a first cooling medium (4.1), and a wall (3) separating the injection channel (5) and the cooling channel (4). The wall (3) has at least one opening (6) or several openings (6) distributed around its circumference, through which a second cooling medium (6.1) can be conveyed and thus introduced into the injection channel (5), or through which a second cooling medium (6.1) is conveyed and thus introduced into the injection channel (5) during operation of the injection nozzle (1).Preferably the opening (6) or openings (6) have an angular extension in the wall (3), wherein the opening(s) (6) extend or extend in a longitudinal section through the injector nozzle (1) to a vertical at an angle between 20° and 80°.

[0018] At least one, or preferably several, injection nozzles (1) can be used to operate a metallurgical furnace (not shown), such as, most preferably, a blast furnace or a direct reduction furnace. The injection nozzle (1) can thus be used as a so-called tuyere on a blast furnace. Hot blast can therefore be used as the gaseous medium (5.1). Preferably, a first, preferably liquid, cooling medium (4.1) can be used for a circulating cooling circuit (not shown), most preferably water.

[0019] Preferably, the second cooling medium (6.1) exiting the opening (6) or openings (6) is captured by the gaseous medium (5.1) and adheres as a flow film (6.2) along the inner surface (5.2) of the injection channel (5). The second cooling medium (6.1) introduced into the injection channel (5) can, for example, comprise carbon monoxide, carbon dioxide, nitrogen, argon, water vapor, hydrogen, hydrocarbons (such as natural gas), coke oven gas, blast furnace gas, higher hydrocarbons, air, or mixtures thereof. The opening(s) (6) can be connected via supply lines arranged within the cooling channel (not shown here) or outside of it, as is common practice for those skilled in the art, so that the second cooling medium (6.1) can be passed through and introduced into the injection channel (5).

[0020] The design and dimensioning of the opening(s) (6) can, for example, first be determined by simulation and then verified in laboratory and / or operational tests.

Claims

1. Injection nozzle (1) with an injection channel (5) extending centrally within the injection nozzle (1) for injecting gaseous media (5.1), a cooling channel (4) arranged radially to the injection channel (5) and extending within the injection nozzle (1) for conveying a first cooling medium (4.1), and a wall (3) separating the injection channel (5) and the cooling channel (4). characterized by the fact that in the wall (3) at least one opening (6) or several openings (6) distributed around the circumference of the wall (3) is or are arranged, through which a second cooling medium (6.1) can be passed and thus introduced into the injection channel (5).

2. Injection nozzle according to claim 1, wherein the opening (6) or openings (6) has or have an angular extension in the wall (3).

3. Method for operating a metallurgical furnace, wherein the metallurgical furnace comprises at least one injection nozzle (1), the injection nozzle (1) having an injection channel (5) for injecting gaseous media (5.1) which extends centrally within the injection nozzle (1), a cooling channel (4) arranged radially to the injection channel (5) and extending within the injection nozzle (1) for conveying a first cooling medium (4.1), and a wall (3) arranged between the injection channel (5) and the cooling channel (4). characterized by the fact that in the wall (3) at least one opening (6) or several openings (6) distributed around the circumference of the wall (3) are present, through which a second cooling medium (6.1) is passed during operation of the injection nozzle (1) and thus introduced into the injection channel (5).

4. Method according to claim 3, wherein the opening (6) or openings (6) has or have an angular extension in the wall (3).

5. Method according to claim 3 or 4, wherein the second cooling medium (6.1) exiting from the opening (6) or openings (6) is captured by the gaseous medium (5.1) and adheres as a flow film (6.2) along the inner surface (5.2) of the injection channel (5).

6. Method according to any one of claims 3 to 5, wherein a blast furnace is used as the metallurgical furnace.

7. Method according to claim 6, wherein hot wind is used as the gaseous medium (5.1).

8. Method according to any one of claims 3 to 7, wherein a first liquid cooling medium (4.1) is used.

9. Method according to claim 8, wherein the liquid cooling medium (4.1, 4.3) is water used first.

10. Method according to any one of claims 3 to 7, wherein a gas is used as the second cooling medium (6.1).

11. Method according to claim 10, wherein the second gaseous cooling medium (6.1) is carbon monoxide, carbon dioxide, nitrogen, argon, water vapor, hydrogen, hydrocarbons, coke oven gas, blast furnace gas, air or mixtures thereof.

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