EP0063549A1

EP0063549A1 - Cooled crown for electric furnaces

Info

Publication number: EP0063549A1
Application number: EP82830070A
Authority: EP
Inventors: Adriano Meroi; Paolo Iuri
Original assignee: DANIELI ENGINEERING SpA; Danieli Eng SpA; Danieli and C Officine Meccaniche SpA
Current assignee: Danieli and C Officine Meccaniche SpA
Priority date: 1981-04-14
Filing date: 1982-03-24
Publication date: 1982-10-27
Also published as: ATE15264T1; DE3265733D1; IT1146768B; ES511361A0; ES8303670A1; GR76696B; EP0063549B1; IT8183360A0

Abstract

This invention concerns a cooled crown (20) for electric furnaces which consists of a plurality of tubular elements and comprises in mutual cooperation and coordination:

- a carrying structure (21) consisting of at least one outer, tubular, perimetric element (24) and of an inner, tubular element (25), whereby the two elements (24-25) are connected hydraulically to each other by appropriate tubular risers (46),
- a plurality of panels (22) to cool the crown, whereby said cooling panels (22) consist substantially of two primary manifolds (26-27) and of a plurality of tubes (28),
- a cap (23) consisting of supporting means which circulate fluid (50),
- and a possible cooling coil (33) which cooperates with the inner tubular element (25).

Description

This invention concerns a cooled crown for electric furnaces. To be more exact, this invention ooncerns a crown cooled by circulation of water under pressure, said crown being suitable for being installed on electric furnaces with or without any additional holes.
Many types of cooled crowns are known; some of them are concerned mainly with the cooling of the area surrounding the electrode, as is the case, for instance, in Russian patent 400787.
Other types provide tubular elements arranged in a cir- .cle, as is the case, for example, in patent US 402I603.
Yet others include a lay-out of substantially parallel. tubes, as is the case in patent US 4I32852, for instance.
Instead, patent US 42I6348 envisages tubes arranged . substantially like a spider's web, while Russian patent 6I767I sets forth a crown with an intermediate chamber suitable for an irregular circulation of water.
Such lay-outs involve many shortcomings either because .they do not permit a controlled expansion of the components or because they do not make possible an even cooling of the surface or because they do not allow the component spaces to be modular.
Furthermore, the lay-outs proposed do not enable energy consumption to be kept low; they are costly and involve very long construction and installation times.
Moreover, the known systems make it necessary to dismantle or indeed to replace the whole crown when the central .ring bearing the electrodes has to be replaced.
Owing to all these shortcomings and to yet others, as will be seen hereinafter in the description, the author has studied, embodied and experimented with a new crown cooled by circulation of water under pressure, said circulation be- .ing obtained owing to a special and characteristic lay-out .of a composite plurality of conduits.
This new type of crown provides many advantages consequent upon the specific pre-set purposes.
One advantage is a considerable reduction in the consumption of refractory material, which leads to an appreciable lessening of the operating costs.
Another advantage is the increase in the life span of .the middle part of the crown, the outcome of this being a .yet greater productivity of the furnace.
A further advantage is the increase in productivity following on the drastic reduction in down times.
Another advantage again is the ability to re-use the water for other purposes too, as it is possible to regulate the heat exchange within preferential selected values.
The invention, therefore, leads to a restraining of energy consumption in that refractory material is envisaged. .as being positioned between one tube and another. Moreover, .the invention enables construction and installation times to be reduced with a noteworthy working safety.
Furthermore, the invention permits easy replacement of. elements in case 6f a breakdown in one or more of said elements.
It is also an advantage that the invention enables the elements themselves to be readily repaired.
Besides, the various panels are suspended and upheld by an independent carrying frame which weighs on the perimeter of the furnace itself, and this fact increases the safety of the overall whole since, amongst other things, the panels are not stressed by dynamic forces.
It is also a considerable advantage that the central ring bearing refractory material can be changed without any need to change the crown itself, and this leads to an appreciable lessening of down times and a great increase in pro-. ductivity.
The invention visualizes a supporting structure which .has at least one outer supporting element having a substant_- ially annular shape and consisting advantageously of a con-. .duit for fluids, said outer element lying dtrectly on the .perimeter of the electric furnace and cooperating with a tubular element which has a circular or, more genertcally, .polygonal shape and which is located within said outer element in a higher position.
Said tubular element is supported by a plurality of .tubular risers connecting the circumferential tubular element with the outer hollow supporting ring so as to permit hy- .draulic continuity in the circulation of the cooled fluid.
. The circumferential tubular element can perhaps include .one or more auxiliary circumferential elements cooperating . .with a possible hole for charging operations carried out .through the crown itself or for other work..
. Panels to cool the crown are fitted below said support- .ing structure so that they are located substantially between said supporting structure itself and the inside of the furnace.
Said panels to cool the crown consist of two tubular elements connected to each other by a plurality of other tubular elements arranged substantially radially and having the advantage of a section possessing an inverted oval development.
A cap consisting of elements with the shape of an inverted "L" are supported on the tubular element.
Said elements with the shape of an inverted "L" can be a plurality of spokes resting on the circumferential tubular element and bearing one or more rows of cooling tubes.
To said spokes is anchored the cap which serves to carry the refractory material that positions and insulates the electrodes.
An appropriate ring for circulation of fluid can be envisaged instead of the plurality of spokes with cooling tubes.
Also, one or more cooling rings can be envisaged as being around the electrodes.
The invention therefore consists substantially of a plurality of parts having well defined functions: a supporting structure consisting of a substantially annular outer . element and of an inner element, said elements being connected to each other hydraulically with appropriate risers, whereby said supporting structure sustains on its lower side a plurality of panels to cool the crown which can be either normal or of a specialized kind, and whereby on the tubular. element is borne a cap which has on its periphery supporting means for circulation of fluid which serve to anchor and position the refractory material connected to the electrodes.
The tubular element can include an auxiliary circumferential element; if so, said auxiliary circumferential element will comprise cooling coil means able to invest the depth of the refractory material itself.
The invention is therefore embodied in a cooled crown for electric furnaces, whereby the cooled crown is composed of a plurality of tubular elements and is characterized by comprising in mutual cooperation and coordination:

- a carrying structure consisting of at least one outer, tubular, perimetric element and an inner tubular element, said two elements being connected to each other hydraulically by tubular risers,
- a plurality of panels to cool the crown, whereby said cooling panels can be normal or of a specialized kind and consist advantageously of two primary manifolds disposed substantially concentrically and of a plurality of tubes which are positioned radially and have a substantially elliptic section with an inverted axis,
- a cap consisting of supporting means which circulate fluid
and possible cooling coil means which cooperate with the inner tubular element.

By referring to the attached tables, which have been given as non-restrictive examples, let us now see a prefer-. ential lay-out of the invention and an embodying variant.
In the tables we have as follows: -

Fig.I gives from above a view of a cooled crown according. to the invention;
Fig.2 shows the solution of Fig.I according to a vertical. diametral section;
Fig.3 shows a section of a detail of the cooled crown; .
Fig.4 shows a modular cooling panel of a non-specialized kind;
Figs.5, 6 & 7 show specific sections as they are embodied in the modular panels of Fig.4;
Fig.8 shows from above a view of a different embodiment of the cooled crown of the invention;
Fig.9 gives a verttcal, diametral section of the solution of Fig. 8;
Fig.I10 shows a detail of the front view of a crosswide section of a cooled panel.

In the attached figures the same parts or parts perform- .ing the same functions bear the same reference numbers.
Figs.I and 2 show an embodiment of the cooled crown 20 of the invention. Said cooled crown 20 consists substantially of a carrying structure 2I able to bear a plurality of cooling panels 22 and of an arch or cap 23 positioned on the middle of the cooled crown 20.
Said carrying structure 2I consists, in this instance, .of an outer, tubular, perimetric element 24 having a circumferential shape and of an inner, tubular element 25 also having a circumferential shape, whereby the two elements 24 .and 25 are connected to each other hydraulically with a plurality of tubular risers 46.
. Said tubular risers 46 are arranged substantially radi- .ally between the tubular elements 24 and 25 so as to form . therewith 24-25, in this example, a circular crown, whereby said circular crown, and substantially the whole cooled crown .20, can be flat or dome-shaped or be disposed in a series .of suspended surfaces.
Said carrying structure 2I bears the cooling panels 22. .by means of welded elements or elements which can be disman- .tled or by means of known means.
Said cooling panels 22, which are divided between spe-. cialized panels and normal panels, depending on how they are .to be employed, have in the example of Figs. I and 3 a form. .consisting substantially of sectors of a circular crown and. .are able, when connected to each other, to occupy a zone .which is conformed like a circular crown and is at least partially lower than the zone occupied by the carrying structure 2I.
The cooling panels 22 normally used consist of two prt- mary manifolds 26-27, which in this instance are conformed . like an arc of a circumference and are positioned concentrically, and of a plurality of tubes 28 connecting the two primary manifolds 26-27 together radially and having at their opposite ends substantially elliptic sections with inverted. principal axes.
This special shape of the tubes 28 enables the cooling. fluid to be distributed evenly over the enveloping surface .divided into sectors of circular crown and occupied by each .cooling panel 22, as shown in Figs. I and 4.
The cooled crown also includes a cooling panel 122 of .a specialized kind for the charging of materials into the .electric furnace, said panel I22 being substantially like .those 22 normally employed.
At least one variant is possible which consists of the. .charging intake 47 delimited by a conduit 30, which has a .toroidal shape and is connected hydraulically to at least .part of the tubes 28 and is disposed in the middle thereof . 28.
Another panel 222 of a specialized kind has an aspiration outlet 29 for fumes which is delimited by a conduit 52 . of toroidal shape connected hydraulically to the inner manifold 26 and to at least part of the tubes 28.
Moreover, it is visualized that above the said outlet 29 there is a second outlet 3I delimited by a conduit 32, . which is connected hydraulically to the carrying structure . 2I and, to be more exact, to the inner, tubular, circumfer-. ential element 25.
Cooling coil means 33 are arranged to pass through the. .two outlets 29 and 3I so as to get better dispersion of the. heat radiated by the fumes leaving the electric furnace at . a very high temperature.
It is possible to exchange the specific uses to which . the two outlets 29 and 47 are put.
Furthermore, the cooling panels 22 are at least partially sunk in a structure of refractory material 34, whereby . said structure of refractory material 34 is put between the. tubes 28 and also substantially around them 28 so as to en-. wrap them, and whereby said structure 34 is supported by . said tubes 28 by virtue of the special inverted-ellipse shape of the latter, as shown in Fig.I0.
Said cooling panels 22, being thus constituted, are welded together so as to form a modular structure conformed, in this instance, like a circular crown.
In substance said panels 22 comprise end joints 35 shaped so as to make possible an easy mutual connection and an easy separation whenever a possible replacement of said panels 22 may be required.
Fig.5 shows a detail of the connection of the tubes 28. .to the manifold 27 and of the connection of said manifold 2? to the conduit 36 delivering or taking away the cooling fluid. .The same kind of connection can be envisaged as existing be- .tween the tubes 28 and manifold 26..
Figs.6 and 7 show means 37 for bleeding off the air and any steam forming in the tubes owing to the high temperature .of the fluid circulating.
. In particular, being lighter than the cooling fluid, the air tends to gather in the high part of the manifold 26, which .in its turn is usually positioned at a level higher than the remainder of the pipes in the panel 22.
. As the turbulence-alone of said cooling fluid is not enough to discharge said steam, said means 37 are employed .to bleed off the air and steam and consist substantially of tubular elements/conformed elbow-wise, of which the intake is turned towards that part of the inner surface of the manifold 26 which is located at the highest level thereof, as shown in Fig.6.
Said Fig.6 also shows a delivery hole 38 able to facilitate the passage of air but to keep to a minimum the passage of cooling fluid.
To allow the air to reach the discharge conduits or bleeder tube 37 there is comprised in said manifold 26 a communicating passage 4I of small dimensions or at any rate, of dimensions such as to let the air filter through preferentially; any cooling liquid will pass through in very small quantities. only.
So as to enable the cooling fluid to circulate inside the tubes of the panel 22 in a desired way, the manifolds 26-27 can be divided by partition walls 40 into separate neighbouring sectors 39, as shown diagrammatically in Figs. 4 and 7.
It is possible, therefore, to arrange said bleeder means37 along the manifold 26 in a desired number so as to. enable the air and steam to be drawn off from said manifold 26.
As said earlier, so as to lessen still further the formation of bubbles or pockets of steam or air inside said manifold 26, some through holes 4I are visualized as being. machined through the uppermost part of the partition walls. 40 so that the neighbouring sectors 39 can communicate with each other. This assists the circulation of the air and the withdrawal of the latter through the bleeder means 37.
Bleeder means 37 the same as or like those described . just now can also be envisaged in the inner tubular element 25.
Fig.3 shows a lengthwise section of a tubular riser 26, which in this instance is conformed so as to permit a two- way circulation of cooling fluid.
It can also be visualized that said cooling fluid circulates in only one direction inside each tubular riser 26,
Indeed, in both cases it is possible to envisage the creation of hydraulically separated neighbouring sectors inside the tubular elements 24-25 so as to pre-set the path of the cooling fluid therewithin 24-25.
Figs.I, 2 and 3 show the cap 23 disposed so as to shut the top of the cooled crown 20.
In particular, said cap 23 is upheld by the carrying structure 2I and is located on the inner, tubular element 25. Owing to this lay-out the cap 23 can be readily exchanged when so needed.
The cap 23 consists substantially of supporting means. 50 which circulate fluid and comprise a plurality of spoke elements 42 arranged radially and conformed, for instance, like an inverted "L", whereby said spokes 42 rest on or are located on the inner, hollow, tubular element 25 and bear one or more rows of cooling tubes 43.
To said supporting means 50 which circulate fluid there is anchored the refractory material 44 which serves to position and insulate the electrodes, whereby said electrodes. can be inserted in suitable through holes 45 machined in said cap 23.
Instead of the plurality of spokes 42 with cooling tubes 43 it is possible to visualize a supporting-structure ring which circulates fluid.
Moreover, one or more cooling rings can be visualized as being around the electrodes.
According to a variant of the embodiment of the invention the cooled crown 20 can also be as shown in Figs, 8 and 9.
In particular, said cooled crown 20 of Figs.8 and 9 has a carrying structure 2I of which the perimetric tubular element 24 consists here of two tubular units I24-224, whereby each of said tubular units I24-224 has cooling fluid running through it in a given direction.
Fig.8 also shows the openings 48-49-I48-I49 for the inflow and outflow of the cooling fluid into and out of the tubular units I24-224.
The substantial differences of the embodying variant as compared to the preceding lay-out consist of the substant- tally triangular shape of the new tubular element 25 and, correspondingly, of the cap 23 as well as of the different. positioning of the aspiration outlet 29 for fumes and of the charging inlet 47.
In particular, said aspiration outlet 29 is positioned inside the corresponding specialized panel 222 and does not affect the cap 23.
Therefore the conduit 32 is not included which in the. preceding case delimited the outlet 29 at its upper part and which was connected hydraulically to the tubular element 25..
The cooled crown 20 comprises supporting means 5I able to permit ready handling for a possible displacement of said cooled crown 20..
Moreover, in the variant shown in Figs.8 and 9 the inlet 47 is machined in the cap 23.
We have described here a preferential embodiment of this invention together with one variant, but other variants are possible for a technician in this field.
Thus the proportions, shapes and sizes can be varied. In particular, it can be envisaged that the cap 23 has a . polygonal shape or that the tubular element 25 is conformed correspondingly or is polygonal; it can also be visualized. that the element 24 has pertmetrtc developments of a different shape, for instance, elliptic, polygonal, etc.
It is also possible to foresee that the engagement or. connection of the tubes 28 with the manifolds 26-27 is different from that shown in Fig.5; in particular, it can be . envtsaged that their 26-27-28 lengthwise axes do not intersect as in said Ftg.5 but are awry.
It is also possible to visualize any desired path of flow of the cooling fluid in the tubes of the cooled crown 20.
Moreover, the use of special valves instead of the bleeder means 37 can be envisaged.
It is possible to visualize cooling panels 22 consisting of one or more circumferential tubes and of tubes branching off from the latter and returning thereto after inverting their own direction.
These and other variants are all possible for a technician in this field without departing thereby from the scope of the idea of the solution.

Claims

I. Cooled crown (20) for electric furnaces, whereby .the cooled crown consists of a plurality of tubular elements .and is characterized by comprising in mutual cooperation and .coordination:
.- a carrying structure (2I) consisting of at least one outer, tubular, perimetric element (24) and of an inner, tubular element (25), whereby the two elements (24-25) are connec.ted hydraulically to each other by suitable tubular risers. (46),

.- a plurality of panels (22) to cool the crown, whereby said cooling panels (22) consist substantially of two primary . manifolds (26-27) and a plurality of tubes (28),

- a cap (23) consisting of supporting means (50) which cir-. culate fluid,

.- and a possible cooling coil (33) cooperating with the inner, tubular element (25).
. 2. Cooled crown (20) for electric furnaces, as in Claim I, characterized by the fact that the panels (22) to cool the crown are panels (I22-222) of a specialized kind.
3. Cooled crown (20) for electric furnaces, as in Claim I, characterized by the fact that the panels (22) to cool the crown are normal panels (22).
4. Cooled crown (20) for electric furnaces, as in Claim I and in Claim 2 or 3, characterized by the fact that at least one of the primary manifolds (26-27) of the cooling panels (22) is substantially concentric with the outer, tubu-Jar, perimetric element (2₄).
5. Cooled crown (20) for electric furnaces, as in Claim I and in Claim 2 or 3, characterized by the fact that the primary manifolds (26-27) of the cooling panels (22) are substantially concentric.
6. Cooled crown (20) for electric furnaces, as in Claim I and in Claim 2 or 3, characterized by the fact that the tubular elements (26-27) constituting a cooling panel (22) . have substantially the same lengthwise form as the part of the hollow tubular elements (24-25) cooperating with them.
7. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 6 inclusive, characterized by the fact that the tubes (28) of the cooling panels (22) have a substantially elliptic section with an inverted axis.
8. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 6 inclusive, characterized by the fact that the tubes (28) . of the cooling panels (22) have a substantially round sect-. ion.
9. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 8 inclusive, characterized by the fact that the tubes (28) of the cooling panels (22) are arranged substantially radi-. ally.
I0. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 8 inclusive, characterized by the fact that the tubes (28) .of the cooling panels (22) are arranged substantially in . loops (II-I2-I3).
II. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterised by the fact that the cooling panels (22) have on their. .outside a structure of refractory material (34) (Fig.3).
12. Cooled crown (20) for electric furnaces, as in Claim .I and in one or another of the Claims thereafter, characterized by the fact. that the cooling panels (22) are at least. partially sunk in a structure of refractory material (34).
I3. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that the tubes (28) of the cooling panels. (22) are at least partially sunk in a structure of refractory material (34).
I4. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim I0 inclusive, characterized by the fact that the inner tubular element (25) is substantially circular.
I5. Cooled crown (20) for electric furnaces, as in Claim _I and in one or another of the Claims thereafter up to Claim I0 inclusive, characterized by the fact that the inner tubular element (25) is substantially polygonal.
I6. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that at least one cooling panel (22) of a. specialized kind cooperates with a conduit (32).
I7. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that at least one cooling panel (22) of a· specialized kind cooperates with coil means (33).
I8. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim I4 inclusive, characterized by the fact that the cooling panels (22) are positioned above the carrying structure (2I).
I9. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim I4 inclusive, characterized by the fact that the cooling panels (22) are positioned below the carrying structure (2I).
20. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that the cap (23) has a peripheral conformation substantially the same as that of the tubular element (₂₅)..
2I. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that the cap (23) includes at least one opening (47) for charging purposes or for discharging fumes.
22. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, characterized by the fact that the cap (23) has supporting means (50) which circulate fluid.