EP0029416B1

EP0029416B1 - Cooling panel for electric arc furnaces

Info

Publication number: EP0029416B1
Application number: EP80830091A
Authority: EP
Inventors: Andrea Pittini
Original assignee: Impianti Industriali SpA
Current assignee: Impianti Industriali SpA
Priority date: 1979-11-14
Filing date: 1980-10-31
Publication date: 1985-01-09
Also published as: YU291080A; AR223249A1; ATE11178T1; IT7983490A0; ES8201728A1; IT1126161B; EP0029416A1; DE3069951D1; BR8007415A; DD154310A1; JPS5682376A; ES496535A0

Description

The subject of this invention is a cooling panel for electric arc furnaces; to be more exact, the subject of this invention is a cooling panel of the type employed to cool the upper band of the wall of the electric arc furnace or to cool the cover of said furnace.
Some rings are formed with box-wise elements within which the cooling water circulates. Of the same type is the down-gate described in CH-A-221.354, according to which said down-gate has its sides and beam part made of a box-wise metal structure, and the water circulates within them.
The integral wiring envisaged in DE-A-2.631.982 to cool the upper band of the wall of the furnace also has a box-wise structure, and according to that patent said element has a refractory lining arranged for its inner surface.
FRA-1.514.515 has instead, two integral box-wise rings, located one above the other, to cool the upper band of the furnace wall and a like structure to cool the furnace cover. In this patent the box-wise elements are connected to the refractory walls with some anchorage means and have in their hollow insides some pipes in which the cooling water circulates.
DE-A-2.659.827 has two box-wise cooling rings, both alike, arranged one above the other. In this case said rings are made in segments connected together and have some protrusions extending into the refractory lining to increase the heat-carrying capacity.
US-A-3.829.595 envisages the use of two rings situated one above the other and made in segments with solid metal blocks connected together; some vertical pipes are visualised within these blocks for the passage of cooling water. Said blocks have a refractory lining and refractory bricks on their inner surface.
DE-U-7616608 envisages, instead, a furnace in which are foreseen three cooling zones disposed symmetrically around the upper band of the furnace wall; each zone comprises a plurality of metal cooling blocks provided with internal pipes in coils for the passage of cooling water; the inner surface of the blocks is equipped with metal protrusions, whilst the outer surface is covered with a metal plate that encloses said cooling pipes.
A like solution is envisaged by US-A-3.849.587 wherein the zones chosen for the cooling are provided with box-wise elements cooled with water, or else there are metal blocks equipped with internal pipes fused to the inside of said blocks.
US-A-3.743.752, US-A-3.777.043 and GB-A-1.193.527 also foresee the installation of box-wise cooling elements to be applied at points where the temperature is very high.
Other rings consist of segmented cooling elements in which a cast iron or copper. block encloses a channel in coils wherein the water circulates, as in US-A-3.843.106, the whole being obtained by casting and the coiled channel protruding partially to correspond with the connecting curves.
In other cases said coiled channel is not enclosed in nor fused to the refractory material nor to the cast iron or copper block as in US-A-3.843.106, but is envisaged as being on the outside of the furnace and of its cover, as in FR-A-873.478, or else said coiled channel is also wound around the electrodes at the inlet for said electrodes as in FR-A-1.238.713. Another layout is visualised in FR-A-1.155.723, which foresees an electric arc furnace consisting of two coaxial jackets located one inside the other and separated from each other by a space; the inner jacket is cooled with gas flowing through said space; whereas the outer jacket is cooled with water coming in at the bottom and going out at the top.
The annular cavity of the water jacket has some vertical channels extending throughout practically all the length of the furnace, and these channels consist of a corrugated metal- foil element fixed between the internal walls of said circular cavity.
These are also other types of rings, but all of them are complex to make and are not very reliable owing to the thermal stresses which they undergo periodically and continuously and which bring about a lessening of the life of the refractory material and thus of the furnace itself.
This lessening of the life increases the cost and the time needed to ready the walls and cover of the furnace.
This invention tends to overcome this problem by the provision of a new cooling panel intended for the construction of the cooling ring or furnace cover.
The invention combines easy manufacture with a safe structure able to absorb any thermal or mechanical shock, and also offers an extremely simple structure to be constructed.
According to the invention a panel of thick plate is cut according to whatever preferential shape is wished. According to the circumstances involved, the panel is bent beforehand or after the successive operations. A plurality of internal channels is made with a tool, and they are connected together with manifolds. As said, the panels are shaped according to the circumstances in question so as to assume a partially cylindrical conformation or a partially truncated-cone conformation before or after the machining has been carried out, or else before or after the closure of the inlets of the connecting pipes. If wished, the manifolds or transit channels may be made at the ends or in an intermediate position by machining the exposed outer surface with a tool and then closing it thereafter with strip or with sheet sealed to the panel by welding.
Next, the inlet and outlet attachments are arranged in any desired suitable position on the outer surface of the panel so as to correspond with the manifolds.
According to the invention the path of the circulating water can be highly varied within the limits allowed by the making of the channels with a tool, whether it be done by drilling (for instance, with a straight-flute drill) or by milling or with a shaping or milling machine for plate, for example.
One purpose of this invention is to envisage a cooling panel which can be machined from plate of a suitable thickness available commercially; said plate must be capable of being worked readily with a tool so as to hold inside itself the cooling channels in a quantity enough for the purpose.
Another purpose of this invention is to visualise a cooling panel with internal channels for the cooling water formed as desired, which can be increased in number and volume, in the zones of higher temperature.
Yet another purpose is to envisage a cooling panel which has a low cost and can be readily and economically replaced or adjusted if found faulty. Again, a purpose is to obtain a cooling panel from thick plate with one or more conduits or manifolds made, perhaps at least partly, in its exposed surface and then closed superficially.
It is an advantageous fact that the panel of this invention does not require auxiliary lining pipes, thus enabling a large reduction to be made in both costs and weight.
It is also an advantageous fact that the cooling channels can be located very near the surface, unlike panels made by casting, which need greater minimum thicknesses. This also enables a greater power of cooling and heat dispersion to be obtained.
Another advantageous fact is that the panel forms a more uniform and efficient block to absorb heat.
Yet another advantage is the ability offered by this invention to envisage a watertight cooling panel made of resilient and homogeneous material with no risks of leakage in the cooling water circuit, while it is also an advantage to be able to instal adequate supports for the refractory material.
The foregoing purposes and advantages together with yet other are attained with a cooling panel intended to constitute the cooling ring or the furnace cover for electric arc furnaces; said panel can be connected to other similar panels to constitute together the required containing and cooling structure.
The invention is therefore realized with a cooling panel for electric arc furnaces, either to form the ring situated higher than the bath or to form the furnace cover, whereby the inner side comprises supports and anchorage means for the refractory material and the outer side inlet and outlet attachments for the cooling liquid, said panel being characterized by the fact that it is made of a plate which has a thickness able to incorporate channels and is cut to a preferential profile, whereby a coordinated plurality of channels substantially contained within the thickness of said plate is obtained by processing with a tool and whereby the plate is shaped according to a preferred profile.
Let us now see a preferential solution of the invention with the aid 6f the attached tables, which are given as non-restrictive examples.
In the figures we have the following:

Fig. 1 shows a circumferential panel with substantially central inlet and outlet attachments;
Fig. 2 shows a straightened, lengthwise, upright section of the panel of Fig. 1;
Fig. 3 shows a crosswise, upright section of the panel of Fig. 1 along the axis of the attachments;
Fig. 4 shows a lengthwise upright section of a variant of the panel of Fig. 1;
Fig. 5 shows a lengthwise, upright section of another variant of the panel of Fig. 1;
Fig. 6 shows a crosswise, upright section of the panel of Fig. 5;
Fig.- 7 shows a cutaway panel for a furnace cover;
Fig. 8 shows a cutaway panel for a furnace cover with a hole provided;
Fig. 9 shows a possible section of the hole of Fig. 8;
Fig. 10 shows a variant of the panel of Fig. 7;
Fig. 11 shows a variant of the panel of Fig. 8;
Figs 12-13 show a head manifold made in the exposed outer surface and then closed;
Fig. 14 shows diagrammatically a possible installation.

The same parts in the figures bear the same reference numbers.
In the figures we have as follows; 20 is a panel for the side of the furnace, while 120 is a panel for the top thereof; the side panel is shaped advantageously as a segment of the circumference, whereas the top panel fits a section of the furnace cover; the top panel may comprise some holes (for the entry of the electrodes, the outlet for fumes, the introduction of inoculants, etc.), which may be positioned in the middle of the panel (as per the examples of Figs. 8 and 11) or at its side or in any other desired position without affecting the purposes of the invention; thus the side panel may include holes for controls and access to suit the usages and requirements; 21, 121 and 22, 122 are respectively the upper and lower sides; said sides, as also the lateral sides 27, may include special profiles or shapings so as to facilitate connections, installation, airtight seal, etc.; 23 is the inner face and may comprise some suitable means 28 of any desired shape and type which can improve and facilitate the installation of the refractory material; 24 is the outer face, from which there protrude advantageously the connecting pipes or attachments 25 and 26 for connection to the delivery or discharge of cooling liquid; 25 and 26 are the inlet and outlet attachments, or viceversa, which serve respectively to feed and discharge the cooling liquid employed; 28 are the anchorages or anchorage means which serve to facilitate the installation and retaining of the refractory material; said anchorage means can be welded, screwed or inserted into appropriate holes and clamped there, for instance, with nuts on the face 24; 29-129-229 are channels acting as an upper manifold; 30-130-230 are channels acting as a lower manifold (the definition of upper and lower manifold here being merely illustrative); 31 and 131 are possible tracts to connect one or both of the attachments to the channels 29 and 30 acting as manifolds; 32 are the conduits which convey the cooling liquid coming from the manifolds; 33 are plugs which are fixed to give a watertight seal at the ends, in the sides and, possibly, in the faces by blocking the channels 29, 30 and 32; the plugs 33 can be screwed, welded or inserted under pressure and can cooperate or not with watertight packings; 34 are the inside plugs which are inserted, for instance, into the manifolds to divide them into sections and to modify the circulation of liquid as wished; 35 is the cover of the channel made in the exposed surface and then closed; said cover may be wholly or partially embedded or be fixed on the outside; 36 is a possible hole in the panels; it serves for very varied uses and may have very varied shapes and sections; it can lie in any desired position in the panel and thus may be situated indifferently in the middle, in an intermediate position or near the edge or may be formed in the edge so as to correspond with the neighbouring panel as well; 37 is the annular manifold channel and can be made in different ways, for instance as shown in Fig. 9; 38 is the closure for the channel 37 and is such as to permit the cooling liquid to circulate around the hole 36 but not to run out; 39 is the shaft of the electric furnace; 40 are the electrodes; 41 are examples of delivery means while 42 are examples of discharge means, but both of them could be inverted; said outer manifolds 41 and 42 are shown connected in a ring but in actual fact can be connected as wished.
The method of working is evident. The liquid enters through 25 or 26 and, after having passed through the manifolds 29 and 30, the conduit 32 and the possible tracts 31 and 131, leaves through 26 or 25.
The method of obtaining the panels 2µ- 12µ is likewise evident, and the sequence of the phases indicated can vary, one being carried out earlier or later than the others to suit the means employed.
Having cut the panel 20-120 according to the peripheral, geometric sizes required, steps are taken to make the channels 29, 30 and 32 and, perhaps, 37.
Said channels can be made wholly or partially with a drill and bit (for instance, with a so- called straight-flute drill for long bores), or with a milling cutter or a rotating tool (for instance, for the channels 37 of Fig. 9), or again with a shaping machine (or milling machine) for plate.
The plugs 33 or closures 35, 135, 38 are then fixed with any desired means such as welding, screwing, pressure, etc.
Fig. 5, in fact, shows the case of a panel wherein a head channel is obtained by milling (shown as an example of a non-through channel), while the other channel 129 serves to connect the various conduits 32 and, perhaps, 31 without said conduits being thereafter plugged as per the examples of Fig. 4 and other solutions.
The conduits 32 can obviously be vertical or horizontal or follow any desired slope.
Fig. 7 shows an example wherein the manifold 30 was made from the beginning as a non-through channel, and the conduits 32 are also not through channels. Moreover, Fig. 7 shows a conduit 32 made, for instance, by milling.
The conduits 32 can lie in any direction in the panel 120.
Fig. 9 show a possible type of collar both for the cooling of the edge of the electrode and for connecting the third or fourth hole.
We have described some variants here, but other are possible for a technician in this field, just as it is possible to introduce integrating and/or replacing modifications or variants without departing thereby from the scope of the idea of the solution.
Thus the proportions and/or sizes can be changed, and other types of courses can be realized; it is possible to make channels wholly by drilling, or partly by drilling and partly by working on the exposed surface and then closing the channel, or all the channels can be made in the open exposed surface and then closed; it is possible to make the manifolds 29, 30 horizontal, almost horizontal, vertical or almost vertical or, in general, in any desired direction; it is possible to make the conduits 32 meet the manifolds 29, 30 at any desired angle; the whole course can consist of one single conduit, and so on.
These and other variants are all possible for a technician in this field.

Claims

1. Cooling panel for electric arc furnaces, either to form the ring situated higher than the bath or to form the furnace cover, whereby the inner side comprises supports and anchorage means for the refractory material and the outer side inlet and outlet attachments for the cooling liquid, said panel being characterized by the fact that it is made of a plate which has a thickness able to incorporate channels and is cut to a preferential profile (21-22-27), whereby a coordinated plurality of channels (29-30-32-37) substantially contained within the thickness of said plate is obtained by processing with a tool and whereby the plate is shaped according to a preferred profile.

2. Cooling panel for electric arc furnaces, as in Claim 1, characterized by the fact that the channels (29-30-32-37) are oriented and connected in a preferred system, whereby at least some of the channels are plugged (33) at their ends so as to form a closed circuit.

3. Cooling panel for electric arc furnaces, as in Claims 1 and 2, characterized by the fact that the plugs (33) are welded.

4. Cooling panel for electric arc furnaces, as in Claims 1 and 2, characterized by the fact that the plugs (33) are screwed.

5. Cooling panel for electric arc furnaces, as in Claims 1 and 2, characterized by the fact that the plugs (33) are forced into position under pressure.

6. Cooling panel for electric arc furnaces, as in any one of the preceding claims, characterized by the fact that the manifolds (29-30-37) are connected to at least one conduit (32).

7. Cooling panel for electric arc furnaces, as in any one of the preceding claims, characterized by the fact that at least part of the manifolds (29-30-37) are obtained from the open exposed surface and have watertight closure elements (35-38).

8. Cooling panel for electric arc furnaces, as in any one of the preceding claims, characterized by the fact that at least part of the conduits (32) are obtained from the open exposed surface and have watertight closure elements (35-38).

9. Cooling panel for electric arc furnaces, as in any one of the preceding claims, characterized by the fact that there is at least one connecting tract (31-131) in the panel (20-120).

10. Cooling panel for electric arc furnaces, as in any one of the preceding claims, characterized by the fact that the plate consists of a metallic material.