Technical field

[0001 ] The present invention generally relates to cooling panels for metallurgical furnaces such as e.g. blast furnaces, and in particular to cooling panels with means for repairing damaged cooling panels.

Background Art

[0002] Cooling panels for metallurgical furnaces, also called "staves", are well known in the art. They are used to cover the inner wall of the outer shell of the metallurgical furnace, as e.g. a blast furnace or electric arc furnace, to provide a heat evacuating protection screen between the interior of the furnace and the outer furnace shell. They generally further provide an anchoring means for a refractory brick lining, a refractory guniting or a process generated accretion layer inside the furnace.

[0003] Originally, the cooling panels have been cast iron plates with cooling channels cast therein. As an alternative to cast iron staves, copper staves have been developed. Nowadays, most cooling panels for a metallurgical furnace are made of copper, a copper alloy or, more recently, of steel.

[0004] The refractory brick lining, the refractory guniting material or the process generated accretion layer forms a protective layer arranged in front of the hot face of the panel-like body. This protecting layer is useful in protecting the cooling panel from deterioration caused by the harsh environment reigning inside the furnace. In practice, the furnace is however also operated without this protective layer, resulting in erosion of the lamellar ribs of the hot face.

[0005] As it is known in the art, while the blast furnace is initially provided with a refractory brick lining on the front side of the staves or steel blades inserted in the grooves of the staves, this lining wears out during the campaign. In particular, it has been observed that, in the bosh section, the refractory lining may disappear relatively rapidly.

[0006] As the cooling panels are worn, mainly by abrasion, the coolant circulating through the cooling channel may leak into the furnace or blast furnace gas may enter the cooling circuit. Such leaks are of course to be avoided. [0007] When such a leak is detected, the first reaction will generally be to stop feeding coolant to the leaking cooling channel until the next programmed stoppage, during which a flexible hose can be fed through the cooling channel, such as e.g. described in JP2015187288A. Subsequently, the flexible hose is connected to coolant feed and coolant may be fed through the flexible hose within the cooling panel. Thus, the metallurgical furnace can be operated further without having to replace the damaged cooling panel.

[0008] However, once the coolant feed through the leaking cooling channel is interrupted, material from the furnace may enter the cooling channel thereby hindering a subsequent installation of the flexible hose.

[0009] A severely worn cooling panel leads to a temperature increase of the copper surrounding the channel, which leads to a loss of copper mechanical properties. In some cases, this may lead to a complete destruction of the cooling late, which leaves the furnace shell directly exposed to high heat loads and to abrasion.

[0010] Also, the installation of the flexible hose into the cooling channel is rather complicated. The flexible hose needs to have smaller diameter than the cooling channel and have a rather thin wall thickness to be manipulated in the angles/corners of the cooling channel. Such a thin wall thickness of the flexible hose does not survive for a long time against abrasion. Thus, the flexible hose only allows prolonging the lifetime of the cooling panel for a short period of time.

Technical problem

[001 1 ] The aim of the present invention is to provide an improved cooling panel, which provides quick and effective repair in case of leaking coolant. A further aim of the present invention is to provide a cooling panel that can be produced faster and with reduced cost. This object is achieved by a cooling panel as claimed in claim 1 .

General Description of the Invention

[0012] The present invention concerns a cooling panel for a metallurgical furnace comprising a body with a front face and an opposite rear face, a top face and an opposite bottom face and two opposite side faces. The body has at least one cooling channel therein, the cooling channel having openings in the rear face. In use, the front face of the body is turned towards a furnace interior.

[0013] According to the present invention, the cooling panel comprises at least one cooling pipe having an elongate middle section and, at either end thereof, an angled branch, the at least one cooling pipe forming the cooling channel.

[0014] The cooling panel further comprises at least one elongate recess formed in the front face of the body, the at least one cooling pipe being arranged in the at least one elongate recess such that the angled branches protrude through the openings in the rear face of the body.

[0015] By installing a cooling pipe in a recess formed in the front face of the cooling panel, such a cooling pipe can be quickly installed, which is of particular interest when a damaged cooling pipe is to be replaced. Indeed, the damaged cooling pipe can be removed from the recess and a new, undamaged cooling pipe can be installed such that the cooling panel is available for further use.

[0016] It should be noted that the cooling pipe of the present invention can also be used to repair a damaged cooling channel of a traditional cooling panel, i.e. a cooling panel that has not been initially conceived to receive such a cooling pipe. Generally, if a traditional cooling panel is damaged, a flexible hose may be passed through the damaged cooling channel in order to attempt to create a coolant passage within the cooling channel. The installation of such a flexible hose is however rather delicate and time consuming. Instead of installing such a flexible hose, it is suggested to form an elongate recess in the front face of the cooling panel and then installing a cooling pipe according to the invention in the newly formed recess.

[0017] The fact that the cooling pipe comprises a middle section and, at either end thereof, an angled branch, is also of particular interest. Indeed, the angled branches of the cooling pipe are formed and arranged so as to protrude out of the rear face of the cooling panel when the cooling pipe is arranged in the body of the cooling panel. These protruding angled branches act as coolant feed pipes that would in prior art solutions been welded onto the rear face of the cooling panel. However, such welding is rather time consuming and thus renders the manufacturing of the cooling panel rather expensive. By providing a cooling pipe with integral feed pipes, such welding is no longer required, thus speeding up the manufacturing process and saving costs.

[0018] Also, the manufacturing of traditional cooling panels requires the forming of a cooling channel in the body, the subsequent forming and shaping of the panel and finally the welding of the feed pipes. With the present invention, the forming and shaping of the body of the cooling panel after installation of the cooling pipe is not required, thus again saving on manufacturing time and cost.

[0019] Advantageously, the cooling pipe has a front face with a profile which, when arranged in the body, matches the profile of the front face of the body. Indeed, the front face of the body may have a structured surface with alternating ribs and grooves. In which case, the front face of the cooling pipe preferably has a matching structured surface with alternating ribs and grooves. Cooling panels indeed generally comprise alternating ribs and grooves on their front face. As the cooling pipe is arranged in a recess in the front face of the body of the cooling plate, a front face of the cooling pipe with a matching structured surface allows for the cooling panel to have the typical general rib and groove structure.

[0020] The front face of the cooling pipe is preferably integrally formed with the cooling pipe. This not only warrants a safe and robust structure, but also allows for a good heat transfer between the front face of the cooling pipe and the coolant passing through the cooling pipe.

[0021 ] The cooling pipe and front face may be formed by extrusion, machining, casting or 3D-printing. The 3D-printing in particular allows forming complex shapes.

[0022] The middle section of the cooling pipe may have round, oblong or rectangular cross-section, depending on the shape of the recess in the body of the cooling panel.

[0023] Advantageously, the elongate recess and the cooling pipe are formed so as to provide a self-locking arrangement, in order to securely maintain the cooling pipe within the elongate recess and to ensure proper conduction heat transfer between the cooling pipe and the body of the cooling panel.

[0024] The elongate recess may comprise a protrusion, while the cooling pipe may comprise a channel for receiving the protrusion therein. Alternatively, of course, the cooling pipe may comprise the protrusion, while the elongate recess comprises the channel. The protrusion and channel may be local or extend over the whole length of the cooling pipe. In order to install the cooling pipe in the elongate recess and engage the protrusion in the recess, the cooling pipe may be forced into the elongate recess with sufficient force to force the protrusion into the channel. Alternatively, the body of the cooling panel may be heated up so that it expands, thereby allowing the protrusion to be arranged in the channel. As the cooling panel subsequently cools down, the cooling panel shrinks and the protrusion is safely arranged in the channel.

[0025] At least one of the ribs of the body and at least one of the ribs of the cooling pipe may be provided with cooperating through holes, wherein the through holes are in alignment when the cooling pipe is arranged within the elongate recess. A bolt may then be arranged through the through holes. Such a bolt allows to secure the cooling pipe within the elongate recess.

[0026] Preferably, the bolt comprises threaded shaft ends and nuts are provided for cooperating with the shaft ends. The tightening of such nuts allows tightly securing the cooling pipe within the elongate recess. This not only prevents the cooling pipe from falling out of the elongate recess, but forces the side walls of the elongate recess to tightly push against the cooling pipe, thereby also improving the heat transfer between the cooling pipe and the body of the cooling panel.

[0027] According to preferred embodiments, the at least one elongate recess is formed in the front face in a direction essentially parallel to the side faces of the body of the cooling panel. If the front face of the body has a structured profile with alternating ribs and grooves, such ribs and grooves are generally arranged in a direction perpendicular to the side faces of the body. Thus, the front face of the cooling pipe should have a profile matching that of the front face of the body; i.e. it should have ribs and grooves.

[0028] According to another embodiment, the at least one elongate recess is formed in the front face in a direction essentially perpendicular to the side faces of the body of the cooling panel. In this case, the elongate recess would be parallel to the ribs and grooves in the front face of the body. Thus, the shaping of the front face of the cooling pipe can be considerable simplified. Preferably, the elongate recess may be entirely formed within the ribs of the front face of the body. Brief Description of the Drawings

[0029] Further details and advantages of the present invention will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings, wherein:

- Fig.1 is a perspective view of a cooling panel according to a first embodiment of the present invention;

- Fig.2 is a perspective view of a body of the cooling panel of Fig.1 ;

- Fig.3 is a perspective view of a cooling pipe of the cooling panel of Fig.1 ;

- Fig.4 is a perspective view of a cooling panel according to a second embodiment of the present invention;

- Fig.5 is a perspective view of a body of the cooling panel of Fig.4;

- Fig.6 is a perspective view of a cooling pipe of the cooling panel of Fig.4;

- Fig.7 is a cross-section view across the cooling panel of Fig.4; and

- Fig.8 is a series of cross-sections across cooling panels according to further embodiments

- Fig.9 is a perspective view of a cooling panel according to a further embodiment of the present invention.

Description of Preferred Embodiments

[0030] Fig.1 schematically shows a cooling panel 10 according to a first embodiment of the invention, wherein the cooling panel 10 comprises a body 12 typically formed from a slab e.g. made of a cast or forged body of copper, copper alloy, cast iron, steel or a hybrid combination of these materials. The body 12 has a front face 14 (often referred to as hot face) for facing the interior of a metallurgical furnace and an opposite rear face 16 (often referred to as cold face) for facing the furnace shell. The essentially rectangular body 12 of the cooling panel 10 has at top face 18 and an opposite bottom face 20 and two opposite side faces 22, 24. At least one cooling channel is arranged within the body 12 for feeding coolant therethrough. The body 12 has openings is the rear face 16 corresponding to the inlet and outlet ends of the cooling channel. [0031 ] As is known in the art, the front face 14 of body 12 advantageously has a structured surface, in particular with alternating ribs 26 and grooves 28. When the cooling panel 10 is mounted in the furnace, the grooves 28 and lamellar ribs 26 are generally arranged horizontally to provide an anchoring means for a refractory brick lining (not shown).

[0032] The cooling panel 10 comprises an elongate recess 30 (better seen in Fig.2) in its front face 14. Such an elongate recess 30 may, as shown in Fig.2, extend from the top face 18 to the bottom face 20.

[0033] The cooling panel 10 further comprises a cooling pipe 32 as shown in Fig.3. Such a cooling pipe 32 has an elongate middle section 34 and at either end thereof, an angled branch 36, 38. The cooling pipe 32 is dimensioned so as to snuggly fit inside an elongate recess 30 in the body 12, while the angled branches 36, 38 protrude from the rear face 16 of the body 12. The middle section 34 of the cooling pipe 34 forms the cooling channel within the body 12, while the angled branches 36, 38 form the coolant feed pipes.

[0034] The cooling pipe 32 further has a front face 40 with a structured surface with cut-out sections 42 forming alternating ribs 44 and grooves 46. The ribs 44 and grooves 46 of the front face 40 of the cooling pipe 32 are formed such that, when the cooling pipe 32 is arranged in the elongate recess 30 of the body 12, they match the ribs 26 and grooves 28 of the front face 14 of the body 12.

[0035] The cooling pipe 32 has a shape that is complementary to the elongate recess 30 formed in the front face 14 of the body 12.

[0036] In order to maintain the cooling pipe 32 in the elongate recess 30, the elongate recess 30 is provided with a protrusion 48 which cooperates with a channel 50 arranged in a lateral portion of the cooling pipe 32 thus providing a self-locking construction.

[0037] Once the cooling pipe 32 is arranged in the elongate recess 30, the cooling pipe is securely maintained in place by the protrusion 48 and channel 50 arrangement. As the cooling pipe 32 has a shape complementary to the elongate recess 30, the cooling pipe 32 and body 12 form the cooling panel 10 and heat transfer between the front face 14 of the cooling panel 10 and the coolant circulating in the cooling pipe 32 is maintained. [0038] Typical cooling panels 10 comprise a plurality of cooling channels in order to provide a heat evacuating protection screen between the interior of the furnace and the outer furnace shell. In the embodiment shown in Figures 1 to 3, a cooling panel 10 is provided with three such cooling channels. In other words, the body 12 comprises three elongate recesses 30 and three cooling pipes 32 arranged therein.

[0039] During operation of a blast furnace or similar, the refractory brick lining erodes due to the descending burden material, causing the cooling panels to be unprotected and exposed to the harsh environment inside the blast furnace.

[0040] The front face 14 of body 12 may be provided with means for protecting the cooling panel against abrasion. One example of such means may be metal inserts (not shown) arranged in the grooves 28, 46.

[0041 ] However, as the cooling panel 10 is exposed to the harsh environment inside the blast furnace, abrasion of the cooling panel 10 and the cooling pipe 32 occurs. If the cooling pipe 32 is damaged, coolant from the cooling pipe 32 can leak into the furnace. In this case, the damaged cooling pipe 32 is removed and replaced with a new, undamaged cooling pipe 32.

[0042] It should be noted that the cooling pipe 32 of the present invention can also be used to repair a damaged cooling channel of a traditional cooling panel. A cooling channel within the body of such a traditional cooling panel is generally obtained by any known means, such as e.g. casting or drilling. A feed pipe is attached to the rear face of the cooling panel by welding and coolant is fed through the cooling channel. The coolant is in direct contact with the material of the body of the cooling panel. If the cooling panel is, in operation, damaged such that abrasion or a crack is formed between the cooling channel and the front face of the cooling panel, coolant from the cooling channel can leak into the furnace. In order to repair such a cooling panel, an elongate recess may be cut into the front face of the cooling panel. A cooling pipe 32 according to the present invention may then be installed in the elongate recess and the cooling panel may be used again.

[0043] Figures 4, 5 and 6 schematically show a cooling panel 10 according to a second embodiment of the invention. As many of the features of this second embodiment are identical with the ones of the first embodiment they will not be repeated here. Mainly the differences are highlighted. As seen in Fig.6, the cooling pipe 32 has a front face 40 which is considerably wider than the cross-section of the middle section 34 it is connected to. Again, the elongate recess 40 in the front face 14 of the body 12 is shaped so as to be complementary to the shape of the cooling pipe 32 such that the cooling pipe 32 snuggly fits therein. Fig.5 also shows the openings 52, 54 in the rear face 16 of the body 12, through which the angled branches 36, 38 are fed.

[0044] In order to secure the cooling pipe 32 in the elongate recess 40, some of the ribs 26 of the body 12 and some of the ribs 44 of the cooling pipe 32 are provided with cooperating through holes 56, 58. When the cooling pipe 32 is correctly arranged within the elongate recess 40, the through holes 56, 58 are in alignment and a bolt 60 is passed therethrough. Fig.7 is a cross-section view across the cooling panel 10 of Fig.4 and shows three cooling pipes 32 arranged in three elongate recesses 40. Fig.7 also shows the shaft 60 passing across the ribs 26, 44 of both the body 12 and the cooling pipe 32. At each end of the shaft 60, a nut 62 may be arranged for cooperating with a threaded end of the bolt 60. By tightening the nuts 62, the connection between the body 12 and the cooling pipe 32 can be made stronger. This not only ensures that the cooling pipe 32 remains in place, but also improves the heat transfer between the cooling pipe 32 and the body 12.

[0045] Fig.8 shows further embodiments of the cooling panel 10 to illustrate further designs. The middle section 34 of the cooling pipe 32 may e.g. have round cross-section as shown in A and C or oblong cross-section as shown in B. In fact, any cross-section that can be obtained by forging, casting or 3D-printing may be envisaged.

[0046] The front face 40 of the cooling pipe 32 may be of various shape and/or width. In A, the front face 40 has a width such that the front faces of neighbouring cooling pipes 32 come into contact with each other such that the front face of the body 12 becomes obsolete. In B and C, on the other hand, the front face 40 of the cooling pipe 32 has a width barely exceeding the cross-section of the middle section 34. It should be noted that these are variations that may be applied to both the first and second embodiments described above. [0047] The body 12 of the cooling panel 10 may be made of copper, steel, cast iron or any alloy based thereon. Similarly, the cooling pipe 32 may be made of copper, steel, cast iron or any alloy based thereon.

[0048] A further embodiment of the invention is shown in Fig.9, wherein the elongate recess 30 is arranged in a direction parallel to the ribs and grooves 26, 28 of the front face 14 of the body 12 of the cooling panel 10. The elongate recess 30 may be entirely arranged within the rib 26; preferably the elongate recess 30 extends over the whole length of the rib 26, i.e. from one side face 22 to the other 24. The front face 40 of the cooling pipe 32 is formed so as to completely fill the elongate recess 30, then the cooling pipe 32 is installed therein, such that the front face 40 of the cooling pipe 32 is flush with the rib 26.

Legend:

10 cooling panel 38 angled branch

12 body 40 front face

14 front face 42 cut-out sections

16 rear face 44 rib

18 top face 46 groove

20 bottom face 48 protrusion

22 side face 50 channel

24 side face 52 opening

26 rib 54 opening

28 groove 56 through hole

30 elongate recess 58 through hole

32 cooling pipe 60 bolt

34 middle section 62 nut

36 angled branch