COOLED CROWN FOR ELECTRIC FURNACES

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: Description of the invention entitled: "COOLED CROtX FOR ELECTRIC FURNACES" This invention concerns a cooled crown for electric .furnaces. To be more ezact, 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 know; some of them .are concerned mainly with the cooling of the area surround Ing 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 4021603. . Yet others include a lay-out of substantially parallel. .tubes, as is the case In patent US 4132852, for instance. Instead, patent US 4216348 envisages tubes arranged substantially like a spider's web, while Russian patent 617671 sets forth a crown with an Intermediate chamber suit able 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 dis- - mantle or tndeed to replace the whole crown when the central .ring bearing the electrodes has to be replaced. - Owing to all these shortcominps and to yet others, as - wfll 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 tng obtained owing to a special and characteristic lay-out - .of a composite plurality of conduits. Thts new type of crow,n provides many advantages conse .quenet upon the specific pre-set purposes. One advantage is a considerable reduction in the con- . sumptton of refractory material, which leads to an appreci- able 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 of a breakdown in one or more of said ele-. ments. 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 peri- - meter 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 appro cable lessening of down times and a great increase in pro-. -ducti vi ty. 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 directly on the perimeter of the electric furnace and cooperating with a tubular element which has a circular or, more generically, - polygonal shape and which is located within said outer ele ment 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 for nace. 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 advantape of a section possessing an inverted oval de velopment. A cap consisting of elements with the shape of an in- verted "L" are supported on the tubular element. Said elements with the shape of an inverted t 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 e - .visaged instead of the plurality of spokes with cooling tubes. Also, one or more cooling rings can be envisaged as be ing around the electrodes. The invention therefore consists substantially of a . plurality of parts having well defined functions: a support ing structure consisting of a substantially annular outer element and of an inner element, said elements being connect ed to each other hydraulically with appropriate rtsers,where- by 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 pa- sition the refractory material connected to the electrodes. The tubular element can include an auxiliary circumfer- central 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 a carrying structure consisting of at least one outer, tw- bular, perimetric element and an inner tubular element, said two elements being connected to each other hydraulic ally by tubular risers, - a plurality of panels to cool the crown, whereby said coo2- ing panels can be normal or of a specialized kind and con sist advantageously of two primary manifolds disposed sub stantially concentrically and of a plurality of tubes which are positioned radially and have a substantially elliptic section with an inverted aris, -- 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-restrictfve 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-specZalized 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 vertical, diametral section of the solution of Fig.8; Fig.IO- 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 21 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 21 consists, in this instance, or an outer, tubular, perimetric element 24 having a circum ferential 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 plu rality 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. .satd 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 21 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 Bone occupied by the carrying structure 21. The cooling panels 22 normally used consist of two pri.- mary manifolds 26-27, which tn this instance are conformed like an arc of a circumference and are positioned concentri.- calls, 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 122 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 aspirat-. ion outlet 29 for fumes which is delimited by a conduit 52 - of toroidal shape connected hydraulically to the inner mani- .fold 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 31 delimited by a condutt 32, which is connected hydraulically to the carrying structure - 21 and, to be more exact, to the inner; tubular, circutfer- ential element 25. Cooling coil means 33 are arranged to pass through the two outlets 29 and 31 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 ts 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.10. 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 27 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 -ts 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 atr and steam and consist substantially of perhaps tubular elements/conformed elbow-wise, of which the Intake is turned towards that part of the inner surface of the mani- fold 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 faci- litate the passage of air but to keep to a minimum the pass age of cooling fluid. To allow the air to reach the discharge conduits or bleeder tube 37 there is comprised tn said manifold 26 a communicating passage 41 of small dimensions or at any rate, of dimensions such as to let the atr filter through prefer enttally; 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 Figsq 4 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 for mation of bubbles or pockets of steam or air inside said manifold 26, some through holes 41 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 rtser 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 ctr culates tn 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 21 and is located on the inner, tubular element - 25. Owing to this lay-out the cap 23 can be readily exchang - ed 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 tL", whereby said spokes 42 rest on or are located on the inner, hollow, tubular element 25 and bear - one or more rozos of cooling tubes 43. To said supporting means 50 which circulate fluid there is anchored the refractory material 44 which serves to pos- - ition 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 tu 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 invent ion the cooled crown 20 can also be as shown tn Figs, 8 and 9. In particular, said cooled crown 20 of Figs.8 and 9 has a carrying structure 21 of which the perimetric tubular element 24 consists here of two tubular units 124-224,where- by each of said tubular units 124-224 has cooling fluid running through it in a given direction. Fug.8 also shows the openings 48-49-148-149 for the inflow and outflow of the cooling fluid into and out of the tubular units 124-224. 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 51 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 perimetric developments of a dtffer.- ent 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 ts dif- ferent from that shown in Fig.5; in particular, it can be . envisaged that their 26-27-28 lengthwise axes do not inter sect as tn said Fig.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 consist ing of one or more circumferential tubes and of tubes branch ing off from the latter and returning thereto after invert tng their own direction. These and other variants are all possible for a technic- ian in this field without departing thereby from the scope - of the idea of the solution.

Claims: C L 1 I X S 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 (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 connect ed 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 (122-222) 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 bear, 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 1 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 wtth an inverted arts. 8. Cooled crown (20) for electric furnaces, as in Claim .1 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 .1 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. 10. Cooled crown 120j for electric furnaces, as in Claim f and in one or another of the Claims thereafter up to Claim s inclusive, characterized by the fact that the tubes (28) . of the cooling panels (22) are arranged substantially in loops (11-12-13). II. Cooled crown (20) for electric furnaces, as in Claim .1 and in one or another of the Claims thereafter, character .ised by the fact that the cooling panels (22) have on their. outside a structure of refractory material (34) (Fig.3). - I2. Cooled crown '(20) for electric furnaces, as tn Claim .1 and tn one or another of the Claims thereafter, character sized by the fact. that the cooling panels (22) are at least partially sunk tn a structure of refractory material (34). 13. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, character ized by the fact that the tubes (28) of the cooling panels (22) are at least partially sunk in a structure of refract ory material (34). 14. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 10 inclusive, characterized by the fact that the inner tub ular element (25) is substantially circular. 15. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim IO inclusive, characterized by the fact that the inner tube ular element (25) is substantially polygonal. 16. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, character sized by the fact that at least one cooling panel (22) of a specialized kind cooperates with a conduit (32). 17. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, character ized by the fact that at least one cooling panel (22) of a specialized kind cooperates with coil means (33). - 18. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 14 inclusive, characterized by the fact that the cooling panels (22) are positioned above the carrying structure (21). 19. Cooled crown t20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter up to Claim 14 inclusive, characterized by the fact that the cooling - panels (22) are positioned below the carrying structure (21)7 20. Cooled crown (20) for electric furnaces, as in Claim I and in one or another of the Claims thereafter, character ized by the fact that the cap (23) has a peripheral conform ation substantially the same as that of the tubular element (25). 21: Cooled crown (20) for electric furnaces, as in Claim I and tn 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 fu- mews. 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 ctrculate fluid.

Inventors: IURI, PAOLO, MEROI, ADRIANO
Applicants: DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1982
Main classification: F27D1
IPC codes: F27D1