CA2874076C

CA2874076C - Side wall cooling for a melting furnace

Info

Publication number: CA2874076C
Application number: CA2874076A
Authority: CA
Inventors: Hans-Erich Lembgen; Jurgen Kunze; Karl-Heinz Kummer; Detlef Strieder
Original assignee: SMS Group GmbH
Current assignee: SMS Group GmbH
Priority date: 2012-05-11
Filing date: 2013-05-08
Publication date: 2016-08-30
Anticipated expiration: 2033-05-08
Also published as: EP2847531B1; EP2847531A1; DE102012214147A1; WO2013167677A1; CA2874076A1; ZA201408198B

Abstract

The present invention relates to a cooling device for a smelting furnace, particularly for cooling a liquid slag (S) in a reduction furnace. In that case the device comprises a lining (3) for lateral screening of a liquid metal melt bath (M) and a liquid slag (S) present thereon, as well as a metal plate (5), which is arranged on a side of the lining (3) remote from the metal melt bath (M) and the slag (S). The metal plate (5) has a plurality of substantially vertically oriented, mutually adjacent slots (13), wherein a respective one of the copper plates (7) extends into the lining (3) through each of the slots (13) substantially perpendicularly to the metal plate (5) and the device further comprises cooling channels (9), which can be flowed through by coolant and which are each arranged between two mutually adjacent slots (13) and the cooper plates (7), which extend through these slots (13), on the side of the metal plate (5) remote from the metal melt bath (M) and the slag (S). The invention is additionally directed to a furnace comprising the cooling device and to a method for producing such a cooling device or such a furnace.

Description

Side wall cooling for a melting furnace Field of the invention The present invention relates to a device for cooling a metal smelt furnace, particularly a reduction furnace.
Prior art Smelting furnaces, particularly reduction furnaces, contain hot metal melts which are covered by a slag layer. This slag layer is frequently very aggressive and can destroy the wall covering of the furnace.
The furnace vessel usually comprises, in the interior, a lining in direct contact with the melt or slag. In order to avoid damage or destruction of the furnace vessel and shutdown times and costs resulting therefrom the inner wall of the furnace has to be constantly cooled. A
metal cladding, which, for example, is cooled by an open trickle cooling, is frequently present on the outer side of the lining. In that case, large quantities of water are needed, which moreover in part run away in uncontrolled manner. A further disadvantage is that in the case of cracks in the cladding, water can reach the lining or melt or slag, which can give rise to undesired and dangerous chemical reactions. In other devices, water boxes are mounted on a side of the cladding remote from the melt and filled with water. The water can indeed thus cool, in particular, the cladding over a large area and in a somewhat controlled manner, but the cooling takes place at a relatively large distance from the actual heat source in the form of the liquid slag.
A cooling element for cooling a metallurgical furnace is known from WO
02/04192 A1, wherein the furnace cladding of the furnace is lined at its side towards the furnace interior space with refractory material. The cooling element comprises a cool part, which is flowed through by coolant and which has a coolant feed and a coolant drain, as well as a hot part cooled by thermal conduction. The hot part of the cooling element is, in the installed state, flush with the face of the refractory material facing into the furnace interior space. The entire hot part is constructed as a plate and a separate cool part is associated with this plate at the cold side.

2 European Patent Specification EP 0 741 853 B1 discloses a cooling device for a furnace, wherein rod-like copper rods extend into a furnace wall. Present on the rear side of the furnace wall is, for example, a metal plate which is cooled over a large area by a water box. At the outset, the complex and costly production of the disclosed system is a disadvantage of the disclosed arrangement. Moreover, in the case of use of a continuous copper plate as rear wall adjoining the furnace wall, copper rods extending from this plate require large amounts of copper. In addition, the load-bearing capability of copper is limited, so that substantial material thicknesses are necessary in order to achieve the requisite stability. Finally, provision of a lining between the copper rods is also significantly hampered.
The technical object of the present invention consists of providing a further developed cooling device for a smelting furnace, particularly for the cooling of the slag region of the furnace, but not of the metal melt bath present thereunder.
In particular, a device of that kind shall be reliable, enable a good cooling performance and/or be economically producible.
A device of that kind should preferably be equally usable for round furnaces.
A further object can consist in overcoming at least one of the above-mentioned disadvantages.
Disclosure of the invention Accordingly, the present invention relates to a cooling device for a smelting furnace, particularly for cooling a liquid slag in a reduction furnace. In that case, the device comprises a lining for (lateral) screening of a liquid metal melt bath and a liquid slag present on the metal melt, as well as a metal plate (or a metal cladding, particularly steel plate), which is arranged on a side of the lining opposite the metal melt bath and the slag.
The metal plate comprises a plurality of slots which are substantially vertically oriented and arranged adjacent to one another (in horizontal direction), wherein a respective one of the copper plates extends through at least some, preferably each, of the slots substantially perpendicularly to the metal plate into the lining and the device further comprises cooling channels, which can be flowed

3 through by coolant and which are each arranged between two mutually adjacent slots and the copper plates, which extend through the slots, on the side of the metal plate remote from the metal melt bath and the slag.
This solution represents above all a cooling which is both effective and economic, because on the one hand the copper plates extend as far as into the lining and on the other hand an economic and effective cooling of the regions between the copper plates is made possible. The disclosed device can in addition be used in round furnaces, for which production of copper elements for cooling of a lining is often made difficult.
In addition, the material requirement of copper can be kept small from the aspect of rising raw material prices. In particular, the metal plate can be constructed from steel or a steel alloy, whereby a high level of stability as well as a saving of cost are made possible. Moreover, the invention is of advantage particularly in the case of aggressive slag baths in which it is of substantial importance for the liquid slag to solidify or 'freeze' on the lining or the copper plates. The thus-formed slag layer can substantially reduce wear of the lining and/or of the copper plates. Moreover, the concept according to the invention allows a high degree of stability of the furnace vessel, since a sufficient region of the metal plate remains between the slots through which the copper plates are introduced into the lining.
According to a preferred form of embodiment the spacing of the mutually adjacent slots corresponds with 1 times to 8 times, preferably 2 times to 6 times, the width of the slots, wherein the thickness of the copper plates preferably respectively corresponds with at least 70%, preferably at least 90%, of the width of the slots. These relationships have proved particularly advantageous for construction of a cooling device which is equally effective and stable.
According to a further preferred form of embodiment of the invention the cooling channels arranged on the metal plate extend over at least a region of a vertical length of 80% of the vertical length or extent of the copper plates, preferably over 100% of this length or preferably even over more than 100% of this length.
According to a further preferred form of embodiment of the invention the cooling channels extend between two mutually adjacent slots (in horizontal direction) over a region of 40%
to 100%, preferably 50% to 90%, of the spacing (considered in horizontal direction) between two mutually adjacent slots.

4 According to a further preferred form of embodiment of the invention the copper plates extend (substantially perpendicularly to the metal plate and/or at the location of the corresponding slot) into the lining over more than 40% of the thickness of the lining or extend preferably over substantially the entire thickness of the lining. The effectiveness of the cooling can be further improved by such an arrangement.
According to a further preferred form of embodiment of the invention the copper plates are in immediate or direct contact with the lining. For preference, at least 50%, preferably at least 75%, of the surface of the plates is in contact with the lining. This feature also serves for further improvement of the cooling performance.
According to a further preferred form of embodiment of the invention the copper plates similarly comprise channels which can be flowed through by coolant and which are preferably arranged in an end region of the copper plates remote from the metal melt bath and the slag. The heat dissipation through the copper plates can thus be increased.
Through an arrangement of the cooling channels in an end region of the plates remote from the slag there is avoidance, inter alia, of water passing into the slag or metal melt, for example in the case of wear or mechanical damage of the plates. In general, the introduction of water or other coolant into the melts or slags can have disastrous effects and result in explosions. Moreover, linings frequently contain alkali compounds which equally should not come into conjunction with water in any circumstances.
According to a further preferred form of embodiment of the invention the lining has a thickness of 400 millimetres to 800 millimetres and preferably a thickness of millimetres to 650 millimetres.
According to a further preferred form of embodiment of the invention not only the lining, but also the steel plate adjoining the lining are respectively of substantially hollow-cylindrical construction so that the hollow-cylindrical lining forms a space for lateral enclosure of the metal melt bath and the slag disposed thereon. The rotationally symmetrical axis of the hollow cylinder preferably lies in vertical direction or can also be described as the longitudinal axis thereof. The circumferential direction of the hollow cylinder preferably lies in a plane perpendicular to the axis of rotational symmetry. Alternatively, both the lining and the metal plate respectively form side walls of a polygonal (particularly rectangular) box.
The invention is additionally directed to a furnace, particularly a reduction furnace, which comprises a cooling device according to any one of the preceding forms of embodiment.
The furnace can preferably be constructed as a round furnace. This means that the volume, which is formed by the lining and the metal casing or the metal cladding, for surrounding a metal melt is constructed to be substantially (circularly) round in a horizontally extending cross-section. The advantages of the furnace relative to the prior art correspond substantially with those of the above-mentioned cooling device.
According to a preferred form of embodiment the cooling device forms a lateral boundary of a furnace vessel for receiving a metal melt bath and a liquid slag present thereabove, wherein the copper plates extend substantially in vertical direction at most over the height of the slag bath. In other words, the copper plates do not extend (in vertical direction) over a region in which the metal melt is present. This region of the lining is preferably free of copper plates.
In addition, the present invention is equally directed to a method for producing a smelting furnace or a cooling device for such, preferably a furnace or a device according to a respective one of the preceding forms of embodiment. In that case, the method comprises at least one of the following steps: providing a metal plate of substantially hollow-cylindrical form with slots, which are arranged adjacent to one another in the circumferential direction of the metal plate and which respectively extend perpendicularly to the circumferential direction; lining-out, in hollow-cylindrical form, the metal plate of hollow-cylindrical form;
and introducing a respective copper plates into each of the slots. The steps can equally be carried out in a different sequence. Moreover, the term "metal plate" or "metal cladding" shall not be understood to be restricted to an integral component.
For example, the metal plate can equally consist of a plurality of elements welded together.
According to a preferred form of the method, this additionally comprises the step of providing cooling channels on the outer wall of the metal plate of hollow-cylindrical form in a region between the mutually adjacent slots (on the side of the metal plate remote from the melt or slag).
According to a further preferred form of embodiment of the method the lining is carried out = 6 in such a manner that the copper plates introduced through the slots contact the lining.
According to a further preferred form of embodiment of the method the copper plates extend over at least 50% of the thickness of the lining. The cooling channels can in general extend perpendicularly to the circumferential direction of the metal plate of hollow-cylindrical form over at least a region of 80% of the length of the slots in the same direction.
All features of the above-described forms of embodiment can be combined with one another or interchanged.
Brief description of the figures The figures of the embodiments are described briefly in the following. Further details can be inferred from the detailed description of the embodiments. There:
Figure 1 shows a schematic side view of an outer wall of a reduction furnace with an embodiment of a cooling device according to the invention;
Figure 2 shows a schematic, horizontal part cross-section of a cooling device or a furnace according to the invention;
Figure 3 shows a schematic, vertical part cross-section of a cooling device or a furnace according to the invention; and Figure 4 shows a schematic, vertical part cross-section of a further cooling device or furnace according to the invention.
Detailed description of the embodiments Figure 1 shows a side view of an embodiment according to the invention of a cooling device. Two copper plates 7 extending substantially perpendicularly to a metal plate or metal cladding 5 (particularly of steel or a steel alloy) are illustrated in the form of a detail, which copper plates project through (longitudinal) slots 13 of the metal plate

5. Each copper plate 7 is preferably indirectly or directly fastened to the metal plate 5 by fastening means 15. The metal plate 5 in that case extends substantially in a vertical direction V.
Such a direction can lie substantially perpendicularly to the melt or the slag meniscus of a metal melt M or slag S in a smelting furnace. The copper plates 7 are preferably provided with cooling channels 11 (not illustrated in Figure 1), which can be supplied with coolant via inlets 17 or outlets 19. A coolant can comprise, for example, water, but also be formed by other liquids. Disposed behind the illustrated view of the metal plate 5 is a lining 3, which is in contact with a melt and/or slag S (not illustrated). Arranged between the mutually adjacent copper plates 7 are, for preference, cooling channels 9 on a side of the metal plate 5 opposite the melt M or slag S or remote from the melt M or slag S. These channels 9 can comprise, for example, metal chambers, which are welded to the metal plate 5 or sealingly screw-connected or riveted thereto. In that case, the channels 9 can extend substantially parallel to the copper plates 7 and/or be arranged in meander-shape between the copper plates 7. The channels 9 can be supplied with coolant by way of inlets 21 or outlets 23. As also illustrated, the coolant channels 9 preferably extend over a large part of the spacing A between two adjacent (but mutually spaced-apart) copper plates 7. The channels preferably similarly extend over at least half the height (in vertical direction) of the copper plates 7 or slots 13 or even, as illustrated, over more than the height of the copper plates 7 or the slots 13. Amongst other things, on the one hand copper material can be saved by the illustrated arrangement, but on the other hand an efficient cooling can be made possible. The copper plates 7 can in general consist of any copper alloy.
A part cross-sectional view of an arrangement, which is similar to Figure 1, in horizontal direction H is illustrated in Figure 2. The copper plates 7 extend in the cross-sectional view in finger-like manner in the lining 3, which is in contact with the slag S or melt M. The metal plate 5 as well as the lining 3 can have a curved shape. In particular, the lining 3 and the metal plate 5 can form a lateral boundary for a metal melt M or slag S
of a round furnace, for example a reduction furnace. In this case, the metal plate 5 and/or the lining 5 is or are of hollow-cylindrical construction. As already described with reference to Figure 1, the copper plates 7 extend from a side (rear side), which is opposite the slag S, of the metal plate 5 through the metal plate into the lining 3. In that case the lining 3 preferably contacts the copper plates 7. The means for fastening the copper plate 7 can comprise angle elements or bracket elements, which protrude substantially perpendicularly from the metal plate 5 on both sides of a copper plate 7, wherein the copper plate 7 is preferably fastened to these elements by bolts or screws. Moreover, the copper plates 7 preferably comprise cooling channels or bores 11. These can be arranged, for improvement in operational reliability, in a region of a copper plates 7 which does not project into the lining 3 or which is disposed on a side of the metal plate 5 remote from the melt M
or slag S.
In general, the lining 3 and/or the metal plate 5 can respectively be of integral construction or composed of a plurality of elements. Thus, the metal plate 5 can, for example, consist of a plurality of (plate-like) elements welded, riveted or screw-connected together. The assembly from a plurality of elements can be advantageous particularly in the case of large furnace diameters in the order or magnitude of up to 25 metres. The lining 3 can, for example, be mortared or cast as usual in the prior art. Moreover, a heat conductive layer, particularly a heat conductive layer containing carbon, can in general be present between the lining 3 and the metal plate 5. This can have, for example, a thickness of several centimetres. However, such layers are familiar to the expert.
Figure 3 shows a schematic part cross-section in vertical direction V. In addition to the components of the cooling device, further elements of a reduction furnace are illustrated, which are not, however, to be regarded as essential for the present invention.
Also shown are the lining 3, the metal plate lying therebehind or on a side of the lining 3 remote from the slag S or melt M, as well as a copper plate 7 protruding into the lining 3 via an opening 13 in the metal plate 5. The copper plate 7 in that case preferably extends over at least half the thickness of the lining 3, whereby an effective cooling or heat dissipation is made possible. Moreover, the copper plate 7 extends in vertical direction V
preferably merely over a region of the slag bath S, but not over the region of the metal melt bath M. In particular, the slag S in contact with the lining 3 and/or the copper plate 7 can thus be transferred into a solid state, whereby damage or wear of these elements is reduced by the slag S.
Figure 4 discloses, analogously to Figure 3, a schematic part cross-section of a cooling device or of a furnace in vertical direction V, but with the difference that the copper plate 7 for further improvement of heat dissipation extends through or over the entire thickness of the lining 3.
The above-described embodiments serve primarily for a better understanding of the invention and should not be understood to be restrictive. The scope of protection of the present patent application arises from the patent claims.

The features of the described embodiments can be combined with one another or interchanged.
Moreover, the described features can be adapted by the expert to existing conditions or applicable requirements.

Reference numeral list 3 lining 5 metal plate 7 copper plate 9 cooling channels 11 cooling channel in copper plate 13 slots in metal plate mounting of the copper plate 17 coolant inlet of the copper plate 19 coolant outlet of the copper plate 21 coolant inlet of the cooling channel 23 coolant outlet of the cooling channel A spacing between two mutually adjacent slots = horizontal direction = metal melt bath = melt / slag / vertical direction / longitudinal direction of the hollow cylinder

Claims

We claim:

1. A cooling device for a smelting furnace, for the cooling of a liquid slag (S) in a reduction furnace, comprising:
a lining (3) for lateral screening of a liquid metal melt bath (M) and liquid slag (S) present thereon;
a metal plate (5) arranged on a side of the lining (3) opposite the metal melt bath (M) and the slag (S); and a plurality of copper plates (7) for cooling the lining (3); wherein the metal plate (5) has a plurality of substantially vertically oriented slots (13) arranged adjacent to one another, wherein a respective said copper plate (7) extends through at least some of the slots (13) substantially perpendicularly to the metal plate (5) into the lining (3) and wherein the device further comprises cooling channels (9), for receiving a flow of coolant and which are respectively arranged between two mutually adjacent slots (13) and the copper plates (7), which extend through said slots (13), on the side of the metal plate (5) remote from the metal melt bath (M) and the slag (S).

2. Cooling device according to claim 1, wherein the spacing (A) of the slots (13) which are adjacent to one another corresponds with 1 times to 8 times, the width of the slots (13) and/or the thickness of the copper plates (7) respectively corresponds with at least 70%, of the width of the slots (13).

3. Cooling device according to claim 1 or claim 2, wherein the spacing (A) of the slots (13) which are adjacent to one another corresponds with 2 times to 6 times, the width of the slots (13) and/or the thickness of the copper plates (7) respectively corresponds with at least 90%, of the width of the slots (13).

4. Cooling device according to any one of claims 1 to 3, wherein the cooling channels (9) arranged on the metal plate (5) extend at least over a region of a vertical length of 80% of the vertical length of the copper plates (7).

5. Cooling device according to any one of claims 1 to 3, wherein the cooling channels (9) arranged on the metal plate (5) extend at least over a region of a vertical length of 100% or more of the vertical length of the copper plates (7).

6. Cooling device according to any one of claims 1 to 5, wherein the cooling channels (9) extend between two mutually adjacent slots (13) in horizontal direction (H) over a region of 40% to 100%, of the spacing between the two mutually adjacent slots (13).

7. Cooling device according to any one of claim 1 to 5, wherein the cooling channels (9) extend between two mutually adjacent slots (13) in horizontal direction (H) over a region of 50% to 90%, of the spacing between the two mutually adjacent slots (13).

8. Cooling device according to any one of claims 1 to 7, wherein the copper plates (7) extend into the lining (3) over more than 40% of the thickness of the lining (3).

9. Cooling device according to any one of claims 1 to 7, wherein the copper plates (7) extend substantially over the entire thickness of the lining (3).

10. Cooling device according to any one of claims 1 to 9, wherein the copper plates (7) have direct contact with the lining (3).

11. Cooling device according to any one of claims 1 to 10, wherein the copper plates (7) comprise coolant channels (11), for receiving a coolant flow.

12. Cooling device as claimed in claim 11, wherein the coolant channels are arranged in an end region of the copper plates (7) remote from the metal melt bath (M) and the slag (S).

13. Cooling device according to any one of claims 1 to 12, wherein the lining (3) has a thickness of 400 millimetres to 800 millimetres.

14. Cooling device according to claim 13, wherein the lining (3) has a thickness of 450 millimetres to 650 millimetres.

15. Cooling device according to any one of claims 1 to 14, wherein the lining (3) and the steel plate (5) adjoining the lining (3) are each of substantially hollow-cylindrical construction so that a space for lateral enclosure of a metal melt bath (M) and a slag (S) present thereon is formed in the interior of the lining (3) of hollow-cylindrical form.

16. A furnace, comprising the cooling device according to any one of claims 1 to 15.

17. Furnace according to claim 16, wherein the furnace comprises a reduction furnace.

18. Furnace according to claim 16 or claim 17, wherein the cooling device forms a lateral boundary of a furnace vessel for receiving the metal melt bath (M) and the liquid slag (S) disposed thereabove and the copper plates (7) extend in substantially vertical direction (V) at most over the height of the slag (S).

19. A method of producing a smelting furnace or a cooling device for such, comprising the following steps:
providing a metal plate (5) of substantially hollow-cylindrical form with slots (13) which are arranged adjacent to one another in the circumferential direction of the metal plate (5) and which each extend perpendicularly to the circumferential direction;
lining-out, in hollow-cylindrical form, the inner wall of the metal plate (5) of hollow-cylindrical form;
introducing a respective copper plate (7) into each of the slots (13); and mounting cooling channels (9) on the outer wall of the metal plate (5) of hollow-cylindrical shape in a region between the mutually adjacent slots (13).

20. Method according to claim 19, wherein the cooling device comprises a cooling device according to any one of claims 1 to 15.

21. Method according to claim 19, wherein the furnace comprises a furnace according to any one of claims 16 to 18.

22. Method according to any one of claims 19 to 21, wherein the lining (3) is carried out in such a manner that the copper plates (7) introduced through the slots (13) contact the lining (3) and/or the lining (3) has slots (13) for introduction of the copper plates (7).

23. Method according to any one of claims 19 to 22, wherein the copper plates (7) extend over at least 50% of the thickness of the lining (3) and/or the cooling channels (9) extend perpendicularly to the circumferential direction of the metal plate (5) of hollow-cylindrical form over at least a region of 80% of the length of the slots (13) running in the same direction.