SECONDARY COOLING CIRCUIT AND MOUNTING ASSEMBLY" DESCRIPTION

[0001] The present invention generally belongs to the field of metal casting .

[0002] More speci fically, the present invention relates to a mounting box for a burner for a metallurgical furnace with a secondary cooling circuit . Moreover, the present invention also relates to a mounting assembly and to a method for cooling said mounting box .

[0003] It is known in the iron and steel industry to melt metals in casting furnaces , e . g . , electric arc furnaces (EAFs ) , which produce steel using an electric arc for melting loads of metal scraps , hot metal , iron-based materials or other metal materials placed in the furnace . [0004] In the casting step, the electric arc and the burners melt the metal load into a pool of molten metal . In particular, burners or blowing lances are integrated inside mounting boxes which have a front wall facing the inside of the furnace .

[0005] The burners or blowing or inj ection lances introduce gas and/or solid substances into the furnace .

[0006] I f the blowing or inj ection lances or burners or similar devices had no protection, they would be directly exposed to electric arcs charged with energy, in addition to the sprays of liquid steel , in addition to the scraps falling from the top into the furnace , with clearly destructive ef fects .

[0007] For this reason, the lances or burners are arranged inside mounting boxes acting as a protection and which are mounted on the furnace wall .

[0008] Such mounting boxes are generally cooled by water circulating inside the wall ( i . e . , in the gap ) forming the mounting box .

[0009] However, the mounting box itsel f is also exposed to the aforesaid same stresses consisting of metal sprays , heat , scraps .

[0010] As a result , in the presence of damage or a defect on the box, the latter must be entirely replaced . However, replacement is possible only by discontinuing the operation of the furnace .

[0011] Since the damage to the box often occurs at 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 which can be removed and replaced in case of damage . Such boxes are known, for example , in documents ITBS20060067 , W003034791 (Al ) .

[0012] Although such a contrivance reduces the number of damage incidents to the front area, in any case it does not eliminate the damage at the edges of the opening accommodating the removable front plate . Since such edges are in any case close to the molten metal bath, they are often subj ect to breakdowns , resulting in the breakage of the inner cooling circuit and water leaks in the molten metal bath .

[0013] Moreover, in case of damage to the box, there is a need to discontinue the melting campaign to allow the replacement of the box, resulting in problems in terms of both lost production and expenditure of energy to restore furnace operation after an undesired stop or in any case for the failed operation of the lances in such a box .

[0014] It is the obj ect of the present invention to solve the aforesaid drawbacks of the mounting boxes of the background art , and in particular, to manufacture a mounting box for lances or burners and a mounting assembly comprising such a mounting box which allows not having to discontinue the melting campaign in progress so as to avoid the immediate switching OFF of the furnace for the replacement of the mounting box in case of a breakdown .

[0015] It is a further obj ect of the present invention to carry out a method of cooling the mounting box which allows a more ef fective cooling and/or allows not having to discontinue the melting campaign in progres s in case of a breakdown of the mounting box . [0016] The aforesaid obj ect is achieved by a lance or burner mounting box, a mounting assembly, a cooling method, and a metallurgical furnace according to the appended independent claims . Preferred embodiments of the invention are defined in the dependent claims .

[0017] The features and advantages of the lance or burner mounting box, the mounting assembly, the cooling method, and the furnace , will be apparent from the following description, given by way of non-limiting example , according to the accompanying drawings , in which :

[0018] - Figure 1 shows a side sectional view of a mounting assembly according to an embodiment of the present invention, installed in a steel furnace according to the present invention;

[0019] - Figure la shows an exploded view of a mounting assembly according to an embodiment of the present invention, in which 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, in which the side wall of the mounting box is shown with phantom lines so that the primary and secondary cooling circuits obtained inside such a wall can be seen;

[0021] - Figure 3 shows a further axonometric view of the mounting assembly in Figure 2 , in which the side wall of the mounting box is shown with phantom lines ;

[0022] - Figure 4 shows a further rear axonometric view of the mounting assembly in Figure 2 , in which the side wall of the mounting box is shown with phantom lines ;

[0023] - Figure 5 shows a front plan view of the mounting assembly in Figure 2 , in which the side wall is not shown with phantom lines ;

[0024] - Figure 6 shows a side view of the mounting assembly in Figure 2 , in which the side wall is not shown with phantom lines ;

[0025] - Figure 7 shows a rear view of the mounting assembly in Figure 2 , in which the side wall is not shown with phantom lines .

[0026] According to the accompanying drawings , reference numeral 1 indicates as a whole a burner or lance mounting box for a metallurgical furnace , adapted to be mounted inside the metallurgical furnace on the side of the molten bath 11 ' and to contain and protect the burner and/or the lance .

[0027] Reference numeral 200 indicates as a whole a mounting assembly comprising the mounting box 1 according to the present invention and a front plate 5 removably mounted and fastened to close a front opening 11 of the mounting box 1 . [0028] The mounting box 1 is adapted to be applied to a metallurgical furnace 300 having a molten bath 11 ' .

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

[0030] The mounting box 1 , as the mounting assembly 200 , are adapted to be installed in the furnace by insertion in the wall 303 of furnace 300 on the outer side , through a wall opening which dimensions are adequate to those of the mounting box 1 . A rear flange 9 fastened to the mounting box 1 acts as a stop device of the mounting box 1 on the furnace wall .

[0031] It is thus apparent 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] The burner or lance mounting box 1 for a metallurgical furnace is thus adapted to be mounted inside the metallurgical furnace on the side of the molten bath 11 ' and to contain and protect burner 81 and/or lance 82 . Such a mounting box 1 is made of metal , preferably entirely of copper or a copper alloy, and is a single piece obtained by casting . The mounting box 1 comprises a box side wall 10 defining an inner cavity 2 adapted to accommodate the burner and/or lance 81 , 82 therein, and a front opening 11 adapted to face the inside of the metallurgical furnace when the mounting box

I is installed in the metallurgical furnace . Moreover, the mounting box 1 comprises a rear opening 12 adapted to be arranged facing the outside of the metallurgical furnace 300 .

[0033] Moreover, the mounting box 1 comprises a primary cooling circuit 3 obtained inside the box side wall 10 and a secondary cooling circuit 4 , fluidically separate from the primary cooling circuit 3 and obtained in the box side wall 10 . The secondary cooling circuit 4 is arranged around the front opening 11 to allow cooling a front portion 110 of the mounting box 1 around the front opening 11 in a separate manner with respect to cooling the remaining mounting box by the primary cooling circuit 3 .

[0034] According to an embodiment , the secondary cooling circuit 4 being arranged around the front opening 11 to allow cooling a front portion 110 of the mounting box 1 around the front opening 11 means that the secondary cooling circuit 4 is arranged close to the front opening

I I and preferably at least partially around the front opening 11 . [0035] It is apparent that according to an embodiment , the secondary cooling circuit 4 is arranged around the front opening 11 so as to surround it almost completely or completely .

[0036] Preferably, the primary cooling circuit 3 is configured to cool predominantly the box side wall 10 and the secondary cooling circuit 4 is configured to cool predominantly 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 , pos sibly except for a possible residual cooling due to the passage of a portion of secondary cooling circuit 4 in the box side wall 10 for conveying the fluid towards the rear opening 12 of the mounting box 1 .

[0038] Preferably, the secondary cooling circuit 4 is shaped so as to surround such a front opening 11 by an angle greater than 270 ° , even more preferably so as to completely surround the front opening 11 , so as to ensure a dedicated cooling in the area most exposed to heat and most subj ect to breaks .

[0039] According to an embodiment , the primary cooling circuit 3 comprises a primary fluid inlet mouth 31 and a primary fluid outlet mouth 32 . Moreover, the secondary cooling circuit 4 comprises a secondary fluid inlet mouth 45 and a secondary fluid outlet mouth 46, distinct from the primary fluid inlet mouth 31 and the primary fluid outlet mouth 32 , so that preferably it is possible to connect separate pipes for two distinct coolant supply systems .

[0040] According to an embodiment , for the connection of two distinct coolant supply systems , the primary fluid outlet mouth 32 is not in fluid communication with the secondary fluid inlet mouth 45 and/or the secondary fluid outlet mouth 46 is not in fluid communication with the primary fluid inlet mouth 31 . For example , this allows having cooling circuits designed in a dedicated manner and adapted to receive respective fluid supplies with dedicated flow rate and pressure parameters .

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

[0042] According to an embodiment , the secondary cooling circuit 4 consists of a single annular channeling 42 annularly arranged around the front opening 11 , a delivery duct 41 which proj ects from the annular channeling 42 and puts the secondary fluid inlet mouth 45 in fluid communication with the annular channeling 42 , and a return duct 43 which proj ects from the annular channeling 42 and puts the secondary fluid outlet mouth 46 in fluid communication with the annular channeling 42 for the fluid heated by the passage in the annular channeling 42 to exit .

[0043] According to an embodiment , the front opening 11 predominantly lies on an inclined front plane Pl incident to a rear plane P2 on which the rear opening 12 lies .

[0044] Preferably, the annular channeling 42 predominantly lies on an inclined channeling plane P4 incident to the rear plane P2 , preferably parallel to the front plane Pl . [0045] The mounting assembly 200 according to the present invention comprises a mounting box as described in the present disclosure , and a front plate 5 removably mounted and fastened to close the front opening 11 of the mounting box 1 .

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

[0047] Burner openings 51 , 52 are obtained on the front plate 5 , adapted to accommodate a head of a burner 81 or lance 82 for the inj ection of gas into the metallurgical furnace .

[0048] According to an embodiment , the front plate 5 also comprises an auxiliary cooling circuit 7 fluidically separate from the primary cooling circuit 3 and the secondary cooling circuit 4 . Such an auxiliary cooling circuit 7 comprises plate channelings obtained in the front plate 5 and adapted to cool the plate by the coolant passing therethrough . Moreover, the auxiliary cooling circuit 7 comprises an auxiliary delivery channeling 71 and an auxiliary return channeling 72 which proj ect from the front plate 5 towards the rear opening 12 and which are accommodated inside the inner cavity 2 . This advantageously allows the front plate 5 to be removed from the outer part of furnace 300 . In other words , the front plate 5 is removable by removing it from the back on the side of the rear opening 12 , rather than from inside the furnace, thus allowing maintenance without the need to switch OFF the furnace .

[0049] It is apparent that the present invention also relates to a mounting assembly 200 described above , in which one or more burners 81 or lances 82 are contained in the inner cavity 2 .

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

[0051] Therefore , it is unequivocally apparent that the method comprises a step aO ) of providing a mounting box according to the present invention, preferably mounted inside the metallurgical furnace 300 on the side of the molten bath 11 ' .

[0052] The method comprises the steps of :

[0053] a ) circulating a first coolant inside the primary cooling circuit 3 ;

[0054] b ) circulating a second coolant , distinct from the first coolant , inside the secondary cooling circuit 4 .

[0055] The independence between the two cooling circuits allows cooling the area around the front opening 11 , which is most subj ect to possible breakdowns , in a more adequate and targeted manner .

[0056] According to an embodiment , step a ) and step b ) are performed simultaneously and the first coolant is a liquid while 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, comprising the steps of : [0059] al) circulating a first coolant inside the primary cooling circuit 3;

[0060] bl) together with step al) , circulating a second coolant, equal to the first coolant, possibly the same coolant, inside the secondary cooling circuit 4;

[0061] cl) discontinuing the circulation of the second coolant in the secondary cooling circuit 4;

[0062] dl) circulating a third coolant, different from the first coolant, preferably a gas or a gas mixture, inside the secondary cooling circuit 4.

[0063] In case of a breakdown close to the area of the mounting box 1 around the front opening 11, the method and the independent secondary cooling circuit thus allow stopping the liquid (water) cooling so that water does not fall inside the metal molten bath 11' . At the same time, the method and the independent secondary cooling circuit thus allow continuing the melting campaign by gas (or gas mixture, e.g., air) cooling in the secondary cooling circuit and by liquid cooling in the primary cooling circuit.

[0064] It is thus apparent 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 such a damaged mounting box 1, comprising the following steps: [0065] a0' ) providing a mounting box 1 according to the present invention, preferably mounted inside the metallurgical furnace 300 on the side of the molten bath 11' , where the mounting box 1 is damaged so as to determine a leak of coolant from the secondary cooling circuit 4, for example, it is damaged close to the front opening 11, preferably in the box side wall 10;

[0066] al' ) circulating a first coolant inside the primary cooling circuit 3;

[0067] bl' ) together with step al' ) , circulating an auxiliary coolant, different from the first coolant, preferably a gas or a gas mixture (e.g., air) , inside the secondary cooling circuit 4.

[0068] It is apparent that the auxiliary coolant can correspond to the third coolant described above for step dl) .

[0069] It is apparent that the cooling methods described in the present disclosure refer to a mounting box or a mounting assembly installed in a steel furnace, and thus provided with all the suitable connections with the liquid or gas cooling circuits provided close to metallurgical furnaces and clearly known to those skilled in the art. Therefore, such cooling circuits and the pumping and interconnection systems thereof are not described in the present disclosure because they are known to those skilled in the art .

[0070] Therefore , by virtue of the presence of a dedicated secondary cooling system arranged in the area of the box most prone to breakdowns , i . e . , the area around the front opening, the mounting box and the mounting assembly according to the present invention innovatively allows further limiting possible damages . Indeed, the secondary cooling system is distinctly designed from the overall primary cooling system of the entire side wall of the mounting box . This al lows designing the cooling channeling in a more targeted and suitable manner for the critical front area to be cooled or a di f ferent type of more ef fective coolant .

[0071] Moreover, according to a further advantageous aspect , the possibility of having two separate and independent cooling circuits allows completing the melting campaign even in case of a breakdown . Indeed, in case 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 with a gas or a gas mixture (preferably air ) which, contrarily to water, do not compromise the metal molten bath . Therefore , by virtue of the present invention, the immediate stopping of the furnace to replace the mounting box is avoided, and the completion of the melting campaign by air cooling and only then the actual replacement of the damaged mounting box once the melting campaign is completed are instead allowed .

[0072] It is apparent that those skilled in the art may make changes to the above-described invention in order to meet speci fic and contingent needs , all contained within the scope of protection as defined by the following claims .