Method for cooling mounting box having secondary cooling circuit for burner of metallurgical furnace

Abstract

A method for cooling a burner or lance mounting box of a metallurgical furnace, comprising: circulating a first coolant inside a main cooling circuit (3); and circulating a second coolant different from the first coolant inside the secondary cooling circuit (4).

Description

Technical Field

[0001] The present invention is generally in the field of metal casting.

[0002] More specifically, the invention relates to a method for cooling a mounting box with a secondary cooling circuit for a burner of a metallurgical furnace. Furthermore, the invention also relates to a mounting box adapted to perform the cooling method, a mounting assembly comprising the mounting box, and a metallurgical furnace comprising the mounting box. Background Art

[0003] As is well known in the steel industry, metal is melted in a casting furnace, such as an electric arc furnace (EAF), which produces steel using an electric arc to melt a metal load such as scrap metal, hot metal, iron-based material or other metallic material placed in the furnace.

[0004] In the casting step, the electric arc and the burner melt the metal load into a molten metal pool. Specifically, the burner or the air blast gun is integrated inside the mounting box, the front wall of which faces the furnace interior.

[0005] Burners or air blowers or injection guns introduce gaseous and / or solid matter into the furnace.

[0006] If the blow guns or jet guns or burners or similar devices are not protected, they will be directly exposed to the energetic arc and will also be damaged by the splashing of liquid steel and the scrap falling into the furnace from the furnace roof, all of which will have obvious destructive effects.

[0007] For this reason, the lances or burners are arranged in a mounting box which serves as a protection and is mounted on the furnace wall.

[0008] Such boxes are usually cooled by water circulating in the walls forming the box, ie in the gaps.

[0009] However, the mounting box itself is also exposed to the same stresses mentioned above including metal splash, heat, and waste.

[0010] Therefore, if the box is damaged or defective, the installation box must be completely replaced. However, the replacement can only be carried out by interrupting the operation of the furnace.

[0011] Since damage to the box usually occurs in the front area of ​​the box, which is most exposed to the molten metal bath, it is known in the art to provide a front plate that can be removed and replaced in the event of damage to the front plate. For example, such a box is known from documents ITBS20060067, WO03034791 (A1).

[0012] Although this design reduces the number of damage events in the front area, it does not in any case eliminate damage occurring at the edges of the openings that house the removable front plate. Since these edges are in any case close to the molten metal bath, they often fail, resulting in damage to the internal cooling circuit and water leaking into the molten metal bath.

[0013] Furthermore, in the event of damage to a cartridge, the melting process needs to be interrupted in order to replace the cartridge, resulting in production losses and energy consumption to restore furnace operation after an unexpected stop or any situation where the lance in such a cartridge is inoperable. Summary of the invention

[0014] The object of the present invention is to solve the above-mentioned disadvantages of mounting boxes of the prior art and in particular to provide a method for cooling mounting boxes and mounting assemblies for lances or burners which is more efficient and / or makes it unnecessary to interrupt the ongoing smelting process, thereby avoiding the immediate shutdown of the furnace for replacing the mounting box in the event of a malfunction.

[0015] Another object of the present invention is to provide a mounting box and a mounting assembly, which can solve the disadvantages of the background art and can also use the above cooling method.

[0016] The above objects are achieved by a cooling method, a mounting assembly, a metallurgical furnace and a mounting box for a lance or a burner according to the attached independent claims. Preferred embodiments of the invention are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The characteristics and advantages of the cooling method, the mounting box for a lance or a burner, the mounting assembly and the furnace of the invention will become apparent from the following description given by way of non-limiting example with reference to the accompanying drawings in which:

[0018] - Figure 1 A side cross-sectional view of a mounting assembly according to an embodiment of the present invention is shown, the mounting assembly being installed in a steelmaking furnace according to the present invention;

[0019] - Figure 1a An exploded view of a mounting assembly according to an embodiment of the present invention is shown, wherein the front plate is separated from the mounting box;

[0020] - Figure 2 shows an axonometric view of a mounting assembly according to an embodiment of the present invention, wherein the side wall of the mounting box is indicated by a dotted line so that the primary cooling circuit and the secondary cooling circuit formed in the wall can be seen;

[0021] - Figure 3 Shows Figure 2Another isometric view of the mounting assembly in, wherein the side walls of the mounting box are represented by dashed lines;

[0022] - Figure 4 Shows Figure 2 Another rear axonometric view of the mounting assembly in, wherein the side walls of the mounting box are represented by dashed lines;

[0023] - Figure 5 Shows Figure 2 A front plan view of the mounting assembly in which the side walls are not represented by dashed lines;

[0024] - Figure 6 Shows Figure 2 A side view of the mounting assembly in FIG. 1 , wherein the side wall is not represented by a dotted line;

[0025] - Figure 7 Shows Figure 2 00140 00141 001413 ... DETAILED DESCRIPTION

[0026] According to the drawings, reference numeral 1 generally denotes a burner or lance mounting box for a metallurgical furnace, which is adapted to be mounted on the side of a molten bath 11 ′ inside the metallurgical furnace and to accommodate and protect a burner and / or a lance.

[0027] Reference numeral 200 generally denotes a mounting assembly comprising a mounting box 1 according to the present invention and a front plate 5 which is detachably mounted and fastened to close a front opening 11 of the mounting box 1 .

[0028] The mounting box 1 is suitable for use in a metallurgical furnace 300 having a molten bath 11 ′.

[0029] The metallurgical furnace 300 comprises a casting vessel 301 containing a metal melt 302 , which is surrounded by a furnace wall 303 , the upper wall of which is usually liquid-cooled, while the lower part is lined with a refractory lining 304 .

[0030] The mounting box 1 as mounting assembly 200 is adapted to be mounted in a furnace by being inserted from the outside into the wall 303 of the furnace 300 through a wall opening adapted to the size of the mounting box 1. The rear flange 9 fastened to the mounting box 1 serves as a stop for the mounting box 1 on the furnace wall.

[0031] It is therefore clear that the present invention also relates to a metallurgical furnace 300 comprising a mounting box 1 or a mounting assembly 200 according to the present invention.

[0032] Therefore, a burner or lance mounting box 1 for a metallurgical furnace is adapted to be mounted on the side of the molten pool 11' inside the metallurgical furnace and to accommodate and protect a burner 81 and / or a lance 82. Such a mounting box 1 is made of metal (preferably, entirely of copper or a copper alloy), and the mounting box is a single piece obtained by casting. The mounting box 1 comprises: a box side wall 10, defining an internal cavity 2 adapted to accommodate a burner 81 and / or a lance 82 therein; and a front opening 11 adapted to face the interior of the metallurgical furnace when the mounting box 1 is installed in the metallurgical furnace. In addition, the mounting box 1 comprises a rear opening 12, which is adapted to be arranged toward the outside of the metallurgical furnace 300.

[0033] Furthermore, the mounting box 1 comprises a primary cooling circuit 3 formed in the box side wall 10 and a secondary cooling circuit 4 fluidly separated from the primary cooling circuit 3 and formed in the box side wall 10. The secondary cooling circuit 4 is arranged around the front opening 11, thereby allowing a front portion 110 of the mounting box 1 around the front opening 11 to be cooled in a manner that is separate from the cooling of the rest of the mounting box by the primary cooling circuit 3.

[0034] According to one embodiment, the secondary cooling circuit 4 is arranged around the front opening 11 to allow cooling of the front part 110 of the mounting box 1 around the front opening 11, which means that the secondary cooling circuit 4 is arranged at a position close to the front opening 11, and preferably, the secondary cooling circuit is at least partially arranged around the front opening 11.

[0035] Obviously, according to one embodiment, the secondary cooling circuit 4 is arranged around the front opening 11 so as to almost completely or completely surround it.

[0036] Preferably, the primary cooling circuit 3 is configured to cool mainly the box sidewalls 10 , while the secondary cooling circuit 4 is configured to cool mainly the front portion 110 of the mounting box 1 .

[0037] Even more preferably, the secondary cooling circuit 4 is configured to cool exclusively the front portion 110 of the mounting box 1 , possibly apart from any residual cooling that may occur due to a portion of the secondary cooling circuit 4 passing in the box side wall 10 transporting fluid towards the rear opening 12 of the mounting box 1 .

[0038] Preferably, the secondary cooling circuit 4 is shaped to surround the front opening 11 at an angle greater than 270°, even more preferably, the secondary cooling circuit is shaped to completely surround the front opening 11 to ensure dedicated cooling in the area most susceptible to heat and failure.

[0039] According to an embodiment, the primary cooling circuit 3 comprises a primary fluid inlet nozzle 31 and a primary fluid outlet nozzle 32. Furthermore, the secondary cooling circuit 4 comprises a secondary fluid inlet nozzle 45 and a secondary fluid outlet nozzle 46 which are different from the primary fluid inlet nozzle 31 and the primary fluid outlet nozzle 32 to enable preferably connecting separate pipes for two different coolant supply systems.

[0040] According to an embodiment, for the connection of two different coolant supply systems, the primary fluid outlet nozzle 32 is not in fluid communication with the secondary fluid inlet nozzle 45 and / or the secondary fluid outlet nozzle 46 is not in fluid communication with the primary fluid inlet nozzle 31. This enables, for example, the cooling circuit to be designed in a dedicated manner and adapted to receive a respective fluid source with dedicated flow rate and pressure parameters.

[0041] Preferably, the primary fluid inlet nozzle 31, the primary fluid outlet nozzle 32, the secondary fluid inlet nozzle 45 and the secondary fluid outlet nozzle 46 are arranged on a rear face 14 of the mounting box 1 arranged around the rear opening 12. Preferably, a flange 9 is fastened to this rear face 14.

[0042] According to one embodiment, the secondary cooling circuit 4 is composed of the following parts: a single annular channel 42, which is arranged in an annular shape around the front opening 11; a delivery conduit 41, which protrudes from the annular channel 42 and connects the secondary fluid inlet nozzle 45 with the annular channel 42 fluid; and a return conduit 43, which protrudes from the annular channel 42 and connects the secondary fluid outlet nozzle 46 with the annular channel 42 fluid, so as to allow the fluid heated by flowing through the annular channel 42 to flow out.

[0043] According to one embodiment, the front opening 11 is mainly located on an inclined front plane P1 intersecting a rear plane P2, wherein the rear opening 12 is located on the rear plane.

[0044] Preferably, the annular channel 42 is mainly located on an inclined channel plane P4 intersecting the rear plane P2, preferably, the channel plane is parallel to the front plane P1.

[0045] The mounting assembly 200 according to the present invention comprises the mounting box described in the present disclosure and a front plate 5 which is detachably mounted and fastened to close the front opening 11 of the mounting box 1 .

[0046] Preferably, the front plate 5 has such a shape that the front plate 5 can be removed from the front opening 11 by pulling the front plate 5 in a direction from the front opening 11 to the rear opening 12 .

[0047] Burner openings 51 , 52 are formed in the front plate 5 , which are adapted to receive the heads of burners 81 or lances 82 for injecting gas into the metallurgical furnace.

[0048] According to an embodiment, the front plate 5 further comprises an auxiliary cooling circuit 7 which is fluidically separated from the primary cooling circuit 3 and the secondary cooling circuit 4. The auxiliary cooling circuit 7 comprises a plate channel which is formed in the front plate 5 and is adapted to cool the plate by a coolant flowing therethrough. Furthermore, the auxiliary cooling circuit 7 comprises an auxiliary delivery channel 71 and an auxiliary return channel 72 which protrude from the front plate 5 towards the rear opening 12 and are housed inside the internal cavity 2. This advantageously enables the front plate 5 to be removed from the outside of the furnace 300. In other words, the front plate 5 can be removed from the rear of the rear opening 12 side rather than from the inside of the furnace, thereby enabling maintenance without shutting down the furnace.

[0049] Obviously, the present invention also relates to the above-described mounting assembly 200 , wherein one or more burners 81 or lances 82 are housed in the internal cavity 2 .

[0050] Furthermore, the present invention relates to a method for cooling a mounting box 1 according to the present invention or a mounting assembly 200 comprising the mounting box.

[0051] Therefore, it is obvious that the method comprises step a0): providing a mounting box according to the present invention, preferably, the mounting box is mounted on the side of the molten pool 11 ′ inside the metallurgical furnace 300 .

[0052] The method comprises the following steps:

[0053] Step a): circulate the first coolant inside the main cooling circuit 3;

[0054] Step b): circulate a second coolant different from the first coolant inside the secondary cooling circuit 4 .

[0055] The independence between the two cooling circuits enables the area around the front opening 11 , which is most susceptible to failure, to be cooled in a more adequate and targeted manner.

[0056] According to one embodiment, step a) and step b) are performed simultaneously, and the first coolant is a liquid and the second coolant is a gas or a gas mixture.

[0057] In particular, the first coolant is preferably water, and the second coolant is air.

[0058] The present invention also relates to a method for cooling a mounting box 1 or a mounting assembly 200 according to the present invention, the method comprising the following steps:

[0059] Step a1): circulate the first coolant inside the main cooling circuit 3;

[0060] Step b1): carried out together with step a1), a second coolant is circulated inside the secondary cooling circuit 4, the second coolant being equivalent to the first coolant and possibly being the same coolant;

[0061] Step c1): interrupting the circulation of the second coolant in the secondary cooling circuit 4;

[0062] Step d1): A third coolant is circulated inside the secondary cooling circuit 4, the third coolant being different from the first coolant and preferably being a gas or a gas mixture.

[0063] Thus, in the event of a failure in the vicinity of the area surrounding the front opening 11 of the mounting box 1, the method and the independent secondary cooling circuit allow the liquid (water) cooling to be stopped, thereby preventing water from falling into the interior of the molten metal pool 11'. At the same time, the method and the independent secondary cooling circuit thereby enable the smelting process to continue by gas (or gas mixture, such as air) cooling in the secondary cooling circuit and liquid cooling in the primary cooling circuit.

[0064] Therefore, it is obvious that the present invention also relates to a method for cooling a damaged mounting box 1 according to the present invention or a mounting assembly 200 comprising the damaged mounting box 1, the method comprising the following steps:

[0065] Step a0'): providing a mounting box 1 according to the present invention, preferably, the mounting box is mounted on the side of the molten pool 11' inside the metallurgical furnace 300, wherein the mounting box 1 is damaged so that the coolant is confirmed to leak from the secondary cooling circuit 4, for example, the mounting box is damaged near the front opening 11, preferably in the box side wall 10;

[0066] Step a1'): circulate the first coolant inside the main cooling circuit 3;

[0067] Step b1′): carried out together with step a1′), an auxiliary coolant is circulated inside the secondary cooling circuit 4 , the auxiliary coolant is different from the first coolant, and is preferably a gas or a gas mixture (eg air).

[0068] Obviously, the auxiliary coolant may correspond to the third coolant in the above step d1).

[0069] Obviously, the cooling method described in the present disclosure involves a mounting box or mounting assembly installed in a steelmaking furnace and thus having all appropriate connections with a liquid cooling circuit or a gas cooling circuit arranged in the vicinity of the metallurgical furnace, which are obvious to a person skilled in the art. Since such cooling circuits and their pumping systems and interconnection systems are known to a person skilled in the art, they are not described in the present disclosure.

[0070] Thus, the mounting box and mounting assembly according to the invention innovatively make it possible to further limit the damage that may occur, thanks to the presence of a dedicated secondary cooling system arranged in the area of ​​the box most prone to failure, i.e. the area around the front opening. In fact, the design of the secondary cooling system is quite different from the integral primary cooling system of the entire side wall of the mounting box. This makes it possible to design the cooling channels more targeted and more suitable for the critical front area that needs cooling, or to adopt different types of more effective coolants.

[0071] Furthermore, according to another advantageous aspect, the possibility of having two separate and independent cooling circuits makes it possible to complete the melting process even in the event of a malfunction. In fact, in the event of damage to the front area of ​​the mounting box around the front opening, the coolant circulating in the secondary cooling circuit can be replaced by a gas or a gas mixture, preferably air, which, unlike water, does not harm the metal bath. Thus, by means of the invention, it is avoided to immediately stop the furnace to replace the mounting box, but it is possible to carry out a process in which the melting operation is first completed by air cooling and then the damaged mounting box is actually replaced only after the melting operation is completed.

[0072] Obviously, those skilled in the art may modify the above invention to meet specific and contingent requirements, all of which are included in the scope of protection defined by the appended claims.

Claims

1. A method for cooling a mounting box, comprising the following steps: Step a0): providing a mounting box (1) for a burner (81) or a lance (82) of a metallurgical furnace (300), the mounting box being adapted to be mounted on the side of a molten pool (11) inside the metallurgical furnace (300) and accommodating and protecting the burner and / or the lance (81, 82), the mounting box (1) being made of metal as a single block by casting, and the mounting box comprising: a box side wall (10), defining an internal cavity (2) adapted to accommodate the burner (81) and / or the lance (82) therein; a front opening (11), adapted to face the interior of the metallurgical furnace when the mounting box (1) is mounted in the metallurgical furnace; and a rear opening (12), adapted to be arranged toward the outside of the metallurgical furnace (300), The mounting box (1) comprises a main cooling circuit (3) formed in a side wall (10) of the box. The mounting box (1) comprises a secondary cooling circuit (4) fluidically separated from the primary cooling circuit (3) and formed in the box side wall (10), the secondary cooling circuit (4) being arranged around the front opening (11) so as to allow cooling of a front portion (110) of the mounting box (1) around the front opening (11) in the following manner: separately cooled relative to cooling of the rest of the mounting box by the primary cooling circuit (3); Step a): circulate a first coolant inside the main cooling circuit (3); Step b): circulate a second coolant different from the first coolant inside the secondary cooling circuit (4).

2. The method according to claim 1, wherein: The step a) and the step b) are performed simultaneously, and wherein the first coolant is a liquid, and the second coolant is a gas or a gas mixture.

3. The method according to claim 2, wherein: The first coolant is water, and the second coolant is air.

4. A method for cooling a mounting box (1), comprising the following steps: Step a0): providing a mounting box (1) for a burner (81) or a lance (82) of a metallurgical furnace (300), the mounting box being adapted to be mounted on the side of a molten pool (11) inside the metallurgical furnace (300) and accommodating and protecting the burner and / or the lance (81, 82), the mounting box (1) being made of metal as a single block by casting, and the mounting box comprising: a box side wall (10), defining an internal cavity (2) adapted to accommodate the burner (81) and / or the lance (82) therein; a front opening (11), adapted to face the interior of the metallurgical furnace when the mounting box (1) is mounted in the metallurgical furnace; and a rear opening (12), adapted to be arranged toward the outside of the metallurgical furnace (300), The mounting box (1) comprises a main cooling circuit (3) formed in a side wall (10) of the box. The mounting box (1) comprises a secondary cooling circuit (4) fluidically separated from the primary cooling circuit (3) and formed in the box side wall (10), the secondary cooling circuit (4) being arranged around the front opening (11) so as to allow cooling of a front portion (110) of the mounting box (1) around the front opening (11) in the following manner: separately cooled relative to cooling of the rest of the mounting box by the primary cooling circuit (3); Step a1): allowing a first coolant to circulate inside the main cooling circuit (3); Step b1) performed together with step a1): circulating a second coolant inside the secondary cooling circuit (4), the second coolant being equivalent to the first coolant and possibly being the same coolant; Step c1): interrupting the circulation of the second coolant in the secondary cooling circuit (4); Step d1): Circulating a third coolant inside the secondary cooling circuit (4), the third coolant being different from the first coolant and preferably being a gas or a gas mixture.

5. A method for cooling a damaged mounting box (1), comprising the following steps: Step a0): providing a mounting box (1) for a burner (81) or a lance (82) of a metallurgical furnace (300), the mounting box being adapted to be mounted on the side of a molten pool (11) inside the metallurgical furnace (300) and accommodating and protecting the burner and / or the lance (81, 82), the mounting box (1) being made of metal as a single block by casting, and the mounting box comprising: a box side wall (10), defining an internal cavity (2) adapted to accommodate the burner (81) and / or the lance (82) therein; a front opening (11), adapted to face the interior of the metallurgical furnace when the mounting box (1) is mounted in the metallurgical furnace; and a rear opening (12), adapted to be arranged toward the outside of the metallurgical furnace (300), The mounting box (1) comprises a main cooling circuit (3) formed in a side wall (10) of the box. The mounting box (1) comprises a secondary cooling circuit (4) fluidically separated from the main cooling circuit (3) and formed in the box side wall (10), the secondary cooling circuit (4) being arranged around the front opening (11) so as to allow a front portion (110) of the mounting box (1) around the front opening (11) to be cooled separately from the cooling of the rest of the mounting box by the main cooling circuit (3), And wherein the mounting box (1) is damaged, so that it is determined that the coolant leaks from the secondary cooling circuit (4); Step a1'): allowing the first coolant to circulate inside the main cooling circuit (3); Step b1′) performed together with step a1′): circulating an auxiliary coolant different from the first coolant inside the secondary cooling circuit (4).

6. The method for cooling a damaged mounting box (1) according to claim 5, wherein: The auxiliary coolant is a gas or a gas mixture.

7. The method for cooling a damaged mounting box (1) according to claim 6, wherein: The first coolant is water, and the auxiliary coolant is air.

8. A cooling method according to any one of the preceding claims, wherein: The main cooling circuit (3) comprises a main fluid inlet nozzle (31) and a main fluid outlet nozzle (32), The secondary cooling circuit (4) comprises a secondary fluid inlet nozzle (45) and a secondary fluid outlet nozzle (46), and the secondary fluid inlet nozzle (45) and the secondary fluid outlet nozzle (46) are different from the primary fluid inlet nozzle (31) and the primary fluid outlet nozzle (32).

9. The cooling method according to claim 8, wherein: The primary fluid outlet nozzle (32) is not in fluid communication with the secondary fluid inlet nozzle (45), and / or the secondary fluid outlet nozzle (46) is not in fluid communication with the primary fluid inlet nozzle (31).

10. The cooling method according to claim 8 or 9, wherein: The secondary cooling circuit (4) is composed of the following parts: a single annular channel (42) arranged in an annular shape around the front opening (11); a delivery conduit (41) protruding from the annular channel (42) and connecting the secondary fluid inlet nozzle (45) with the annular channel (42) fluid; and a return conduit (43) protruding from the annular channel (42) and connecting the secondary fluid outlet nozzle (46) with the annular channel (42) fluid, so as to allow the fluid heated by flowing through the annular channel (42) to flow out.

11. A cooling method according to any one of the preceding claims, wherein: In the step a0), a front plate (5) is also provided, which is installed and fastened in a detachable manner to close the front opening (11) of the mounting box, and a burner opening (51, 52) is formed on the front plate (5), and the burner opening is adapted to accommodate the head of a burner (81) or a lance (82) for injecting gas into the metallurgical furnace, and the front plate (5) includes an auxiliary cooling circuit (7) fluidically separated from the main cooling circuit (3) and the secondary cooling circuit (4), and the auxiliary cooling circuit (7) includes: a plate channel formed in the front plate (5) and adapted to cool the front plate by allowing a coolant to flow through the plate channel; and an auxiliary delivery channel (71) and an auxiliary return channel (72), which protrude from the front plate (5) toward the rear opening (12) and are accommodated inside the internal cavity (2).

12. A steelmaking furnace adapted to carry out the method according to any one of claims 1 to 11.

13. An installation box (1) for a burner (81) or a lance (82) of a metallurgical furnace (300), the installation box being adapted to perform the steps in the cooling method according to any one of claims 1 to 11, and the installation box comprising the technical features in step a0) or step a0') in the cooling method according to any one of claims 1 to 11.

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