Nozzle for metallurgical furnace

Abstract

The present invention provides a tuyere comprising a conical hollow tuyere body having an inner surface and an outer surface. The present tuyere extends along a first axis from an inlet end to an opposite outlet end. The tuyere body has a tip of the tuyere at the outlet end and a conical connection surface at the inlet end. The conical connection surface is configured to engage a conical seat of a tuyere holder or a tuyere cooler. Advantageously, the tuyere further comprises a corrugated portion on the outer surface of the tuyere. The corrugated portion comprises at least one recess having an open curved contour and a surface surrounding the at least one recess. The corrugated portion is arranged and configured to support the charged material and form a scaffold for the charged material during the operation of the metallurgical furnace.

Description

Technical Field

[0001] The present invention generally relates to the field of metallurgical furnaces, and more particularly to tuyeres for gas injection in metallurgical furnaces having an improved lifespan.

Background Art

[0002] Tuyeres (tuyeres, injection nozzles) are important components of metallurgical furnaces such as blast furnaces. They can inject gas at a location away from the furnace wall to prevent damage to the furnace wall. In modern blast furnaces, usually more than 20 tuyeres are provided around the furnace wall. Tuyeres are usually inserted into tuyere coolers having a circuit for a cooling fluid. The tuyere and the tuyere cooler are tightly press-fitted into an opening in the furnace wall called a tuyere cooler holder. Furthermore, the tuyere itself generally also has at least one circuit for a cooling fluid. Due to the extremely harsh conditions in the tuyere chest, the tuyeres and often the tuyere coolers are damaged and may need to be replaced after a while. The components of the tuyere often get charred or worn, hindering the normal function of the furnace. Such damage also causes gas leakage or water leakage outside the furnace, posing a risk to the health and safety of the workers around the furnace. Currently, tuyeres with a single-chamber design cooling circuit that wear due to abrasion or refining and start to leak into the furnace are bypassed, leading to a complete failure. This means an unscheduled shutdown of the metallurgical furnace to replace the defective tuyere. The lifespan of the tuyere ranges from several days to several months depending on the tuyere design and the productivity of the metallurgical furnace, and requires regular maintenance work at relatively short time intervals. The unscheduled operation stoppage of the metallurgical furnace for replacing a defective tuyere lasts at least 4 to 8 hours. The production losses caused by such stoppages economically exceed the cost of the entire set of tuyeres installed in the furnace. Therefore, the development of tuyere components for metallurgical furnaces, particularly tuyeres, with improved resistance to heat and impact from liquid metal droplets, trajectory materials, or descending loads is important in the operation of the blast furnace itself. Solutions have been developed to improve the design of the tuyere and enhance its wear resistance. Most of these improvements involve either coating the outer surface with a wear-resistant layer or providing more cooling pipes in the tuyere. Among the solutions known in the art, Patent Document 1 discloses coating the tip of the tuyere and the outer surface of the tuyere with a wear-resistant alloy, which includes both a wear-resistant transition layer for enhancing the adhesion to the tuyere material and a wear-resistant operation layer provided at the top of the wear-resistant transition layer to enhance wear resistance. The use of such a wear-resistant alloy improves the tuyere's resistance to wear but will not protect the tuyere from damage caused by liquid metal droplets, orbital materials, or dropped chargers. Therefore, tuyere breakage is only delayed and not completely prevented. Another solution is disclosed in Patent Document 2. This tuyere includes two nose pipes and three different cooling pipes arranged on top of each other to form a stack between the inner and outer surfaces of the tuyere. According to Patent Document 2, the wear on the outer surface of the tuyere leading to leakage of the outermost cooling pipe can be bypassed by this pipe only, rather than the entire tuyere, as the remaining two cooling pipes still provide sufficient cooling. However, such a tuyere is time-consuming and expensive to manufacture and does not solve the problem of excessive wear on the outer surface of the tuyere. Object of the Invention Accordingly, an object of the present invention is to provide an improved design of a tuyere for a metallurgical furnace having a long lifespan without the aforementioned drawbacks.

[0003] This object is solved by the tuyere according to claim 1. Summary of the Invention

[0004] The present invention overcomes the above-mentioned deficiencies and drawbacks by providing a tuyere for a metallurgical furnace, which comprises a conical hollow tuyere body having an inner surface and an outer surface. The tuyere extends along a first axis from an inlet end to an opposite outlet end, the tuyere body having a tip of the tuyere at the outlet end and a conical connection surface at the inlet end. The conical connection surface is configured to engage with a conical seat of a tuyere holder or a tuyere cooler.

[0005] The tuyere further comprises a corrugated portion provided on the outer surface of the tuyere. The corrugated portion comprises at least one recess having an open curved contour and a surface surrounding the at least one recess. The corrugated portion is arranged and configured to support the charged material and form a scaffold for the charged material during the operation of the metallurgical furnace. In other words, the falling charged material is held within the recess and agglomerates both within the recess and on the surface of the corrugated portion. Thus, the corrugated portion promotes the formation of a scaffold for the charged material and holds this scaffold in place. This scaffold protects the tuyere not only from wear due to liquid metal droplets and impact from the orbital material, but also from the falling charge.

[0006] Furthermore, the thickness of the tuyere from the inner surface to the outer surface comprises a thicker portion, and at least one recess of the corrugated portion is provided inside the thicker portion. In other words, the tuyere has an eccentric shape that creates an extra thickness of tuyere-forming material on a part of the outer surface of the tuyere. At least one recess of the corrugated portion is formed with this extra thickness so that the tuyere does not become locally weak. The extra thickness provides the stability and support force required to form the corrugated portion.

[0007] The corrugated portion is preferably arranged on the upper outer surface of the tuyere, i.e., the part of the outer surface that is close to the falling charged material and where the falling material may agglomerate.

[0008] In the context of this application, "corrugated" means a series of preferably parallel ridges and recesses. In other words, in this specification, the corrugated portion is the surface that appears like a series of waves when viewed from one end of the tuyere. In the context of this application, the term "recess" means a recessed space on the surface and is meant as a synonym for a narrow groove, groove or corrugation.

[0009] The main advantage of the tuyere is to support, promote and increase the formation of a scaffold thereon, thereby forming a protective layer. Such a protective layer for the charged material acts like a heat-insulating layer, reducing the heat load on the tuyere and, as a result, attenuating the pick-up of the heat load.

[0010] Furthermore, during the operation of the metallurgical furnace, the falling charge, lining materials, and liquid metal droplets advantageously agglomerate on the scaffold and reinforce the scaffold. Heat and / or abrasion may damage the scaffold, but do not damage the tuyere. In other words, since the scaffold can be continuously consumed and regenerated during the operation of the metallurgical furnace, the outer surface of the tuyere is protected by the scaffold without being exposed to the harsh conditions of the metallurgical furnace. Since damage caused by heat and / or abrasion mainly occurs on the scaffold of the charging material, damage to the tuyere is strongly limited, and the lifespan of the tuyere is dramatically improved.

[0011] Advantageously, the tuyere with a corrugated portion has sufficient resistance to ensure continuous operation of the tuyere even if some loss of the tuyere forming material occurs under heat radiation, due to the scaffold of the charging material that is constantly formed and updated.

[0012] In other words, such a tuyere that enables and promotes the formation, renewal, and regeneration of the scaffold of the charging material at the tuyere top is protected from excessive heat loads and abrasion / erosion wear without the need to change the furnace process parameters (such as blowing and composition of the charge, etc.).

[0013] Holding the charging material and forming a self-protective adhesion layer like the scaffold of the charging material corresponds to the so-called stone box effect.

[0014] Another advantage of such a tuyere is that at least one recess of the corrugated portion has an open curved contour. The recess can exhibit any kind of contour, such as circular, square, or triangular, as long as the contour spreads from the inner surface to the outer surface of the tuyere.

[0015] Such an open curved contour is easier to manufacture than a closed curved contour, such as a dovetail design. In fact, a recess with an open curved contour can be directly cast during the manufacture of the tuyere and does not require subsequent manufacturing processes, while a closed curved contour requires machining or milling of the tuyere to remove the material corresponding to the recess.

[0016] In an embodiment, the corrugated portion may be made of an alloy of nickel, chromium, zirconium, titanium, and / or tungsten, whereby the corrugated portion is further protected from falling droplets and wear.

[0017] For example, a recess coated with a layer of a protective material such as a refractive material is also within the scope of the present invention disclosure. However, in a preferred embodiment, it is preferred that the recess is not filled to the edge with the protective material so as to accommodate and hold the charged material falling to form a scaffold during the operation of the blast furnace.

[0018] Another advantage is that the tuyere design changes include / incorporate the formation of the corrugated portion on the outer surface. These changes are directly incorporated into the tuyere manufacturing process, i.e., are carried out simultaneously with the tuyere.

[0019] Since there is no need to provide additional protective components such as an additional protective layer on the outer surface of the conventional tuyere, or to provide, arrange, and fix additional protrusions or ribs on the outer surface of the tuyere, the costs associated with these changes are substantially non-existent or at least significantly reduced. In other words, at least one recess of the corrugated portion is directly formed on the outer surface of the tuyere, and the surface surrounding at least one recess is the outer surface of the tuyere.

[0020] Yet another advantage of the tuyere is that it does not require a design change to the entire assembly. These tuyeres can be easily used in new metallurgical furnaces or can be used to retrofit existing furnaces during maintenance operations such as replacing a damaged tuyere.

[0021] In a preferred embodiment, the corrugated portion comprises a plurality of recesses, and each recess of the plurality of recesses has an open curved contour. Preferably, the corrugated portion comprises between 3 and 11 recesses, and more preferably, the corrugated portion comprises between 5 and 9 recesses.

[0022] In an embodiment, the surface of the corrugated portion surrounds the plurality of recesses. This may extend between each of the plurality of recesses.

[0023] Advantageously, the corrugated surface with a plurality of recesses easily holds the falling charging material, thereby improving the formation of the scaffold and the resulting stone box effect.

[0024] In the same or an alternative embodiment, each recess of the corrugated portion may be discontinuous. The resulting stone box effect is maximized by the adhesion of the charging material within the recesses and at the top of the tuyere.

[0025] In a preferred embodiment, the recesses are parallel to each other and extend essentially along a second axis.

[0026] Advantageously, the second axis is not coaxial with the first axis. The fact that the second axis is not coaxial with the first axis means that the recesses are arranged and oriented so as to form an angle with respect to the axis of the tuyere. The higher the angle, the better the retention of the charging material inside the recesses, and thus the formation of the scaffold protecting the upper outer surface of the tuyere is improved. If the first and second are coaxial, the charging material is not retained by the recesses because the recesses are oriented along the flow of the falling material.

[0027] Preferably, the second axis is perpendicular to the first axis. When the recesses are arranged perpendicular to the direction of the flow of the charging material, the retention of the falling charging material, the formation of the scaffold, and the resulting stone box effect are thereby maximized. This particular orientation of the recesses enhances the protection of the tuyere against excessive heat load and wear, and thus extends its life. However, a mountain shape is also possible for the orientation.

[0028] The recesses may have any shape, but it is preferred that all the recesses have a similar shape. In an embodiment, the recesses may have a linear shape, i.e., the recesses are formed as a straight line presenting an open curved profile. Alternatively, the recesses may have a wavy shape or an angular shape.

[0029] Advantageously, the tuyere can be made of any metal material or an alloy of any metal material to ensure resistance to heat and wear. However, the tuyere is preferably made of copper, a copper alloy, steel, or a steel alloy.

[0030] In an embodiment, the surface of each recess forming the corrugated portion is covered with a layer of a metal material or an alloy of a metal material to further enhance the wear resistance to heat and wear. Such an additional layer provides additional protection against wear by falling charged materials and droplets of liquid metal (mainly iron). Preferably, the surface of each recess is covered with a layer of copper, a copper alloy, nickel, a nickel alloy, steel, or a steel alloy.

[0031] According to the same or an alternative embodiment, the surface of the corrugated portion and / or the tip of the tuyere is covered with a layer of a hard coating material such as a Cr / Fe alloy and / or a Cr / Ni alloy such as Inconel 625. Hard coating is the deposition of a thick coating of a hard and wear-resistant material on the surface of a wear-prone component or a new component during use. This is usually welded to the base material and generally takes the form of a special electrode for arc welding or a filler rod for oxyacetylene and gas tungsten arc welding. The surface covered with the hard coating material is the surface most exposed to heat and wear. Covering them with the hard coating material improves heat resistance and wear resistance.

[0032] The tuyere can be of any type. In particular, the tuyere may comprise a single chamber, a double chamber, and / or a spiral chamber. In a preferred embodiment, the tuyere further comprises a cast-in nose pipe and a double chamber, where the double chamber can preferably be made of an inner chamber and a spiral bellows pipe. Advantageously, the inner chamber and the bellows pipe prevent leakage from the nose pipe even if the tip of the tuyere wears. The second chamber (inner chamber or bellows pipe) of the double chamber design provides backup cooling when the first chamber (bellows pipe or inner chamber) is not sufficient to ensure sufficient cooling of the tuyere and / or is damaged.

[0033] Preferably, the nozzle pipe is made of a metal material or an alloy of a metal material. More preferably, the pipe is made of copper, a copper alloy, nickel, a nickel alloy, steel or a steel alloy. Such materials have a high refining temperature, thereby providing the pipe with wear and protection against liquid iron droplets after the outer surface of the tuyere has worn.

[0034] In an embodiment, the tuyere further comprises an injection channel arranged and configured to directly inject the charging material above the tuyere during operation of the metallurgical furnace. Advantageously, such an injection channel promotes the formation of a scaffold within and above the recess of the corrugated portion, thereby improving the thermal and wear protection of the tuyere.

[0035] According to the same or another embodiment, the tuyere further comprises a linear path arranged and configured for using an electronic thickness measuring device during operation of the metallurgical furnace.

[0036] Another object of the present invention is to provide a method for manufacturing a tuyere according to the present invention. In an embodiment, the tuyere is manufactured by machining, casting, welding, forging, or any combination of these manufacturing methods. Preferably, the recess of the corrugated portion is manufactured by casting.

[0037] Yet another aspect of the present invention is to provide a metallurgical furnace comprising a tuyere arranged to supply hot gas into the metallurgical furnace, wherein the tuyere is a tuyere according to the present invention.

[0038] <F The method according to the present invention and the metallurgical furnace according to the present invention retain all the advantages of the tuyere according to the present invention.

Brief Description of the Drawings

[0039] Further details and advantages of the present invention will become apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0040] In a metallurgical furnace, in order to supply high-temperature gas into the furnace, several tuyeres 10 are generally arranged inside the furnace wall 12. As shown in FIG. 1, the tuyere 10 is usually arranged in the furnace wall 12 inside the tuyere cooler 14 and then in the tuyere holder 16. The tuyere 10, the tuyere cooler 14 and the tuyere holder 16 are firmly wedged to each other by a conical surface that narrows in the direction of the inside of the furnace.

[0041] The tuyere 10 has a conical hollow tuyere body 18 having an inner surface 20 and an outer surface 22. The tuyere body 18 extends along the first axis A-A from an outlet end 24 that opens into the furnace to an inlet end 26 that receives the tip of the blow pipe 28.

[0042] The outer surface of the tuyere is provided with a corrugated portion 34 as shown in FIG. 2. The corrugated portion 34 is formed on the upper part 30 of the outer surface 22 of the tuyere 10. In this specification, the adjectives upper side and lower side must be considered as referring to the relative orientation of the tuyere in the operating position, that is, the orientation of the tuyere installed in the metallurgical furnace. Therefore, the upper part 30 of the outer surface 22 is the part of the outer surface facing the top of the furnace, and the lower part 32 of the outer surface 22 is the part of the outer surface facing the bottom of the furnace.

[0043] As shown in the embodiment of FIG. 2, the corrugated portion 34 includes seven recesses 36 arranged and configured to support the charged material and form a scaffold for the charged material at the top of the tuyere 10 during operation of the metallurgical furnace. The corrugated portion 34 must include at least one recess 36 for holding and supporting the falling charged material. However, the corrugated portion 34 can have any suitable number of recesses 36 to obtain the desired effect according to the characteristics of the tuyere such as its length and the operating conditions of the metallurgical furnace. As a result, the embodiment of FIG. 2 is only an exemplary and non-limiting embodiment.

[0044] The recesses 36 are preferably formed directly on the outer surface 22 of the tuyere 10, that is, each recess 36 forms a recessed groove or space recessed from the outer surface 22 of the tuyere 10. As is apparent from FIGS. 2 to 4, the surface surrounding the recess is the outer surface of the tuyere.

[0045] The recesses 36 are evenly distributed along the length of the corrugated portion 3 . In an alternative embodiment, the space between two adjacent recesses may vary from one group of two recesses to an adjacent group (not shown). For example, the space between two adjacent recesses may be larger near the inlet end of the tuyere. Alternatively, the space may be larger near the outlet end of the tuyere.

[0046] The recesses 36 are not formed as one continuous recess, but as non-continuous parallel recesses 36 . As shown in FIGS. 2 to 4, the recesses 36 have a linear shape and a rounded open curved profile 38 to facilitate the holding and support of the falling charged material to form its scaffold on the upper part 30 of the outer surface 22 of the tuyere 10. The recesses 36 may exhibit any suitable shape, such as a wavy or angular shape, and any type of open curved profile, such as a square or triangle (not shown).

[0047] The parallel recesses 36 extend essentially along the second axis B-B. The second axis B-B is perpendicular to the first axis A-A of the conical hollow tuyere body 18. In other words, the recesses 36 are perpendicular to the axis of the tuyere body 18. Such an orientation of the recesses maximizes the retention of the falling charge material, the formation of a scaffold, and the resulting stone box effect.

[0048] Even if not explicitly shown, any alternative embodiment in which the second axis B-B is neither perpendicular nor coaxial to the axis A-A of the tuyere body is also part of the present invention disclosure and remains within the scope of the present invention.

[0049] According to the embodiment shown in the cross-sectional views of FIGS. 3 and 4, the tuyere 10 comprises a cast-in nose pipe 40, a helical bellows pipe 42, and an internal chamber 44. Each of the helical bellows pipe 42 and the internal chamber 44 is formed between the inner surface 20 and the outer surface 22 of the tuyere body 18. The helical bellows pipe 42 is closer to the outer surface 22 than the internal chamber 44, and the internal chamber 44 is closer to the inner surface 20 than the helical bellows pipe 42. A person skilled in the art will know the appropriate dimensions of the various pipes depending on the design of the tuyere. However, suitable pipes can be selected from pipes having an inner diameter ranging from 1 / 4 inch to 2 inches.

[0050] According to the embodiment shown in FIG. 4, the tuyere body 18 is made of copper, while each surface of the recesses 36 is coated with a layer 46 of copper, copper alloy, nickel, nickel alloy, steel or steel alloy. The outer surface 22 of the upper part 30 of the tuyere 10 with the corrugated part 34, thus surrounding the recesses 36, and the surface of the corrugated part 34 extending between the recesses 36 are covered with a hard coating material 48. The tip of the tuyere is covered with the same hard coating material 48. In an embodiment, two different hard coating materials can be used to cover the tip of the tuyere and the upper outer surface of the surface. The pipes of the nose pipe 40 and the helical bellows pipe 42 are made of copper, copper alloy, nickel, nickel alloy, steel or steel alloy.

[0051] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description should be considered to be illustrative or exemplary and not restrictive, and the present invention is not limited to the disclosed embodiments.

Explanation of Signs

[0052] 10 Tuyere 12 Furnace wall 14 Tuyere cooler 16 Tuyere holder 18 Tuyere body 20 Inner surface 22 Outer surface 24 Outlet end 26 Inlet end 28 Blower pipe 30 Upper part 32 Lower part 34 Corrugated part 36 Recess 38 Open curved contour 40 Cast-in nose pipe 42 Spiral bellows pipe 44 Internal chamber 46 Recess coating 48 Hard coating material Axis of A-A tuyere Axis of B-B recess

Prior Art Documents

Patent Documents

[0053]

Patent Document 1

Patent Document 2

Claims

1. A tuyeres for a metallurgical furnace, comprising a conical, hollow tuyeres body having an inner and outer surface, extending along a first axis from an inlet end to an opposite outlet end, the tuyeres body having a tuyeres tip at the outlet end, and a conical connecting surface at the inlet end, the conical connecting surface being configured to engage with a conical seat of a tuyeres holder or tuyeres cooler, wherein the tuyeres further comprises a corrugated portion on the outer surface of the tuyeres, the corrugated portion comprising at least one recess having an open curved contour and a surface surrounding the at least one recess, and the corrugated portion is positioned and configured to support the charged material and form a scaffold for the charged material during operation of the metallurgical furnace, A tuyeres for a metallurgical furnace, wherein the thickness of the tuyeres from the inner surface to the outer surface includes a thicker portion, and at least one recess of the corrugated portion is provided in the thicker portion.

2. The tuyere according to claim 1, wherein the corrugated portion comprises a plurality of recesses, each of the plurality of recesses having an open curved contour, preferably the corrugated portion comprises between 3 and 11 recesses, more preferably the corrugated portion comprises between 5 and 9 recesses, and the surface of the corrugated portion surrounds the plurality of recesses and extends between each of the plurality of recesses.

3. The tuyere according to claim 1 or claim 2, wherein each recess in the waveform portion is discontinuous.

4. The tuyere according to claim 1 or 2, wherein the recesses are parallel to each other and extend essentially along a second axis, and the second axis is not coaxial with the first axis.

5. The tuyeres according to claim 4, wherein the second axis is perpendicular to the first axis.

6. The tuyere according to claim 1 or claim 2, wherein the recess has a linear shape.

7. The tuyere according to claim 1 or claim 2, wherein the recess has a wavy or angular shape.

8. The tuyeres according to claim 1 or claim 2, wherein the tuyeres are made of a metal material or an alloy of a metal material, preferably made of copper, a copper alloy, steel, or a steel alloy.

9. The tuyere according to claim 1 or claim 2, wherein the surface of each recess forming the corrugated portion is covered with a layer of a metal material or an alloy of a metal material, preferably the surface of each recess is covered with a layer of copper, a copper alloy, nickel, a nickel alloy, steel, or a steel alloy.

10. The tuyere according to claim 1 or claim 2, wherein the surface of the corrugated portion and the tip of the tuyere are covered with a layer of hard coating material.

11. The tuyeres according to claim 1 or 2, wherein the tuyeres comprises a single chamber, a double chamber, and / or a helical chamber.

12. The tuyeres according to claim 1 or claim 2, wherein the tuyeres further comprises a cast-in nose pipe.

13. The tuyere according to claim 12, wherein the pipe of the nose pipe is made of a metal material or an alloy of a metal material, preferably the pipe is made of copper, a copper alloy, nickel, a nickel alloy, steel, or a steel alloy.

14. The tuyeres according to claim 1 or 2, further comprising an injection path arranged and configured to directly inject a charge material onto the tuyeres during the operation of the metallurgical furnace.

15. A method for manufacturing a tuyere according to claim 1 or claim 2, A method for manufacturing the tuyeres by machining, casting, welding, forging, or any combination thereof.

16. The method according to claim 15, wherein the recess of the corrugated portion is manufactured by casting.

17. A metallurgical furnace comprising a tuyere arranged to supply high-temperature gas inside the metallurgical furnace, wherein the tuyere is the tuyere described in claim 1 or claim 2.

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