CA2053935C - Device for injecting preheated air into a shaft furnace and process for manufacturing ball-and-socket joints - Google Patents
Device for injecting preheated air into a shaft furnace and process for manufacturing ball-and-socket joints Download PDFInfo
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- CA2053935C CA2053935C CA002053935A CA2053935A CA2053935C CA 2053935 C CA2053935 C CA 2053935C CA 002053935 A CA002053935 A CA 002053935A CA 2053935 A CA2053935 A CA 2053935A CA 2053935 C CA2053935 C CA 2053935C
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- ball
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- central
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B7/00—Blast furnaces
- C21B7/16—Tuyéres
- C21B7/163—Blowpipe assembly
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- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Joints Allowing Movement (AREA)
- Manufacture Of Motors, Generators (AREA)
- Furnace Housings, Linings, Walls, And Ceilings (AREA)
- Furnace Charging Or Discharging (AREA)
- Thermotherapy And Cooling Therapy Devices (AREA)
- Direct Air Heating By Heater Or Combustion Gas (AREA)
- Air Supply (AREA)
- Heat Treatment Of Articles (AREA)
- Tunnel Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Thermal Insulation (AREA)
Abstract
The device for injecting preheated air into a shaft furnace consists of a plurality of tubular elements provided with a refractory lining, which are connected to each other by a ball-and-socket articulation (94, 96) and an expansion joint. The ball-and-socket articulations comprise a convex ball-part formed in the refractory material of the adjacent segment. They comprise a protective shell made of refractory steel which extends around the convex part up to the base of the ball-part. The radius of curvature of each ball-and-socket articulation is in the range of magnitude of half the diameter of the tubular elements.
Description
P-PWUa235 ~3~~~~J~
DEVICE FOR INJECTING PREHEATED AIR INTO A SHAFT FURNACE AND
PROCESS FOR MANUFACT~7RING BALL-AND-SOC1KET JOINTS
The present invention relates to a device for injecting preheated air into a shaft furnace, consisting of a plurality of separate cylindrical elements, each consisting of an external steel easing and an internal refractory lining and comprising at least one central tubular element connected, on one side, by a first ball-and-socket articulation and a first expansion joint to an upper connection piece integral with a preheated air feeding bustle pipe surrounding the furnace and, on the other or opposite side, by a second ball-and-socket articulation and a second expansion joint to a lower connection piece extended by an elbow and a blast nozzle, the latter being articulated on a tuyere installed in the wall of the furnace, and in which device the ball-and-socket joints comprise a convex ball-part formed by the end of one of the connection segments and pivoting in a concave socket-part formed by the end of the adjacent connection segment and a soft refractory joint interposed therebetween.
These devices, more generally known under the name of "tuyere-stock", are subject to problems of mobility and sealing. In fact, as a result of high temperature of the preheated air (a temperature of the order of 1200°C or more) and of the high temperature prevailing inside the furnace, the wall of the latter and the bustle pipe and the tuyere-stock are subject to thermal expansions and deformations which cause significant relative displacements between the bustle pipe and the wall of the furnace. The tuyere-stock must therefore be capable of compensating for these relative displacements, whilst at the same time preventing leaks of gas or preheated air.
To meet these requirements, US Patent 3,766,868 provides a tuyere-stock of the type described in the introduction. This tuyere-stock has since been improved by the design of universal ball-and-socket joints like those d U
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z described in the German patent specification DE-C2-2218331.
The three joints of this tuyere-stock make it passible to compensate all the relative movements between the bustle pipe and the wall of the furnace. Sealing in the region of the joints is obtained by means of bellows expansion joints, whilst mechanical stability is ensured by means of cardan connections associated with the two opposite ends of the central tubular element in the region of the two universal joints.
The most stressed and most critical part is always located in the place of the joints . In fact, the mobility of the ball-part with respect to its socket often leads to irreversible distortions of the soft joints and to frictions among refractory materials. In addition, given the difficulties to machine refractory steel, it is not possible to extend the armouring, forming the casing of the ball-part, to the tip of the latter. That is the main reason why microcracks are often formed in the refractory of the tip of the ball-part, causing disturbing circulations and whirls.
To these quality criteria of a reliable tuyere-stock are added the concern for a competitive manufacturing price, for the possibility of easy and rapid dismounting, for the possibility to easily renew the refractory material if necessary, etc. It is obvious that all those criteria often tend to oppose each other, thus forcing the designer and manufacturer to choose a reasonable compromise.
The object of the present invention is to provide a new device of the type described in the introduction, which is more resistant to wear at the place of the joints, which owing to its numerous alternative solutions, adapts itself perfectly to the requirements of the user, while permitting a reasonable manufacturing price.
In order to achieve this object, the device according to the present invention is characterized essentially in that the radius of curvature of each ball-and-socket joint ~~J
is in an order of magnitude of half the diameter of the different connection elements and in that the convex ball-parts of the ball-and-socket joints comprise a protective sheath or sleeve made of refractory steel and which extends to the diametrical base of the ball-part. The reduction of the radius of curvature of the ball-and-socket joints allows a better guiding of the ball-parts in their sockets, while reducing the risks of shock and wear of the soft joints by permmitting to keep always the same width for a joint.
The reduction of the radius of curvature of the joints and the fact that the metallic armouring or casing, which at this place, forms the sheath of the ball and extends to the base of the latter, allows to maintain a uniform width of the joint slot or groove during the pivotments.
The present invention also provides a new process for manufacturing a convex ball-part of ball-and-socket joints of a device far injecting preheated air into a shaft furnace, said process consisting in first fabricating the ball sheath or sleeve of refractory steel and to provide it with an inner refractory lining, and being characterized in that the end of a refractory steel pipe is distorted until it has the form of a convex dome with a central opening and a convex spherical surface extending between the central opening and the cylindrical surface of the pipe, in that the sheath thus formed is placed on a support, in that a cylinder having a diameter slightly inferior to the diameter of said central opening, is placed axially inside, and in that refractory material is cast between the cylinder and said sheath by using the latter as a mould.
According to a first embodiment of a tuyere-stock according to the invention, the ball-parts are formed by the lower ends of the upper connection element and of the central tubular element.
w ~~ )>~J,~~3 The ball--part of the central tubular element can either be an integral part of this element, or be separated from the latter by a transverse junction filled with an annular joint.
The armouring of the central tubular element and the one of the lower connection pipe can be connected directly to each other through an expansion joint, or by means of a flange or an detachable weld.
The socket of the lower joint can be formed into the refractory lining cast in a cylindrical sheath made of refractory steel and arranged coaxially inside the armouring of the lower connection piece.
The soft refractory joint can be fixed partially to the armouring and partially to the rim of the socket. It can also be partially fixed to an inner seat of the cylindrical sheath and partially to the refractory material.
Alternatively, it can also be attached partially to the refractory material and partially to a seat delimited by the upper part of the sheath and by a ring welded inside the armouring.
According to a second embodiment, the sockets of both ball-and-socket joints are arranged at the two opposite ends of the central tubular element, whilst the convex ball-parts are arranged in the upper and lower connection pieces.
Other particular features and adavantages of the invention will be appreciated and understood by those skilled in the art from the following detailed description of several embodiments, with reference to the accompanying drawings in which:
- Figure 1 shows a view, in vertical section, of a conventional foyers-stock according to US Patent 3,766,867;
- Figure 1a shows an alternative embodiment of the lower joint of the tuyere-stock according to Figure 1;
- Figure 2 shows the details of a joint of a tuyere-stock as disclosed in German Patent DE-C2-2218331;
- Figures 3 and 3a illustrate in juxtaposition and in axial section a ball-and-socket joint according to the present invention;
- Figure 4 illustrates schematically the process making a sheath of refractory steel, for a ball-part of a joint connection according to the present invention;
Figure 5 shows diagrammatically an axial section through the vertical section of a first embodiment of a tuyere-stock according to the present invention;
- Figure 5a illustrates schematically an alternate execution of the lower joint of the tuyere-stock according to Figure 5;
- Figures 6a, 6b and 6c illustrate schematically the different manufacturing steps of the refractory lining of the different elements of the tuyere-stock depicted in Figure 5;
- Figure 7 is a similar view to that of Figure 5 of a second embodiment of a tuyere-stock according to the present invention;
- Figures 8, 9 and 9a illustrate different alternate embodiments of the lower joint connection of the tuyere-stock according to Figure 7;
- Figures 10a, 10b and 10c illustrate schematically the different manufacturing steps of the refractory lining of the different elements of the tuyere-stock depicted in Figure 7;
- Figure 11 illustrates schematically a third embodiment of a tuyere-stock according to the present invention;
- Figures 12a, 12b et 12c illustrate schematically the different manufacturing steps of the refractory lining of the tuyere-stock depicted in Figure 11;
- Figure 13 illustrates schematically a fourth embodiment of a tuyere-stock according to the present invention and :~ , s~ -.
~~'~~r~~W3 - Figures 13a, 13b and 13c illustrate schematically the different manufacturing steps of the refractory lining of the tuyere-stock depicted in Figure 13.
The known tuyere-stock, designated by the reference 20 in Figure 1, connects a main bustle pipe 22, arranged around a blast furnace, to the wall 24 of the blast furnace. This tuyere-stock 20 comprises a straight oblique section consisting of a central tubular element 26 articulated with its upper end on a connection piece 28 fixed to the bustle pipe 22 and at its lower end on a connection piece 30 flanged to an elbow 32. This elbow 32 is extended by a nozzle 34, the end of which is articulated on a tuyere 36 fastened in the wall 24 of the furnace. The upper joints 38 and lower joints 40 between the central tubular element 26 and the two connection pieces 28 and 30 are universal joints allowing relative shifts or movements between the bustle pipe 22 and the wall of the furnace 24.
Sealing in the region of the joints 38 and 40 is obtained by means of bellows expansion joints 44, 46 fixed respectively to the tubular element 26 and the adjacent connection pieces 28 and 30. Mechanical stability is ensured by means of cardan joints 48, 50 likewise connecting the central element 26 to the adjacent connection pieces 28 and 30. All these elements of the tuyere-stock consist of an outer-metal armouring or housing 52 provided with an inner refractory lining 54, through which passes a supply channel or conduit 56 ensuring the passage of the preheated air.
each one of the two joints 38, 40 consists of a convex part called ball and of a concave part called socket. In the upper joint 38, the ball is part of the upper connection piece 28 and penetrates into the socket formed by the upper end of the central element 26. The lower part of the latter constitutes the ball-part of joint 40 and penetrates into the socket formed by the upper part of the lower connection piece 40.
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In the embodiment of Figure 1, the ball-part of the joint 40 is integral with the central element 26, that is, its refractory lining extends, without interruption, from the upper end to the tip of the ball-part. This design of the central element 26 makes its manufacture easier, compared with the alternative solution illustrated in Figure 1a, where the ball-part is separated from the rest of the central element and is connected to the latter in the region of the flange, which is provided for the , fastening of the cardan 50a. The alternative solution illustrated on figure 1a presents however the advantage of allowing the separate dismounting of the lower part, which consists of the tubular connection piece 30 and the joint 40a, from the upper part consisting of the rest of the central element 26 and the upper joint 38 with the tubular connection piece 28. It shall be noted that the upper joint 38 must necessarily be designed as shown in Figure 1a, so that the tuyere-stock can be disconnected from the bustle pipe 22.
Figure 2 shows a known embodiment of a joint connection as disclosed in the German patent DE-C2-2218331. This embodiment is different essentially from that one depicted in Figure 1 in that the joints are spherical, as shown by the joint between the ball part 58 and the socket of the connection piece 30. In this embodiment, the ball-part 58 is also separated from the central element 26, following the example of Figure 1a. The embodiment according to Figure 1 is, nevertheless, also feasable here.
Another difference as compared with the embodiment of Figure 1 is the arrangement of soft resilient joints in the region of the ball-and-socket joint. A first sealing ring 62 consisting, for example, of ceramic fibers is incorporated in the refractory of the socket 60 and closes the pasage way between the socket 60 and the tip of the ball-part 58. Another soft seal 64, also made of ceramic fibers, is arranged in the annular space between the lower ~~J'?3 end of the metallic sheath 68 of the ball-part 58 and the cylindrical connection sleeve of the expansion joint 44.
This seal 64 is wedged between the edge of the socket 60 and a peripheral collar 66 welded to the sheath 68.
The purpose of these joints 62 and 64 is essentially to stop or to reduce the penetration of hot air inside the expansion joints 44 in order to provide them a better protection against high temperatures. when the ball-part 58 is subjected to an axial shift relative to the connection piece 30, the lower edge of the sheath 68 may distort or even crush the seal 64 on one side, whereas on the opposite side, the collar 66 tends to compress the seal 64 in the axial direction. Given that the refractory joints are lacking elasticity, there is a risk that these shifts cause irreversible distortions, thus reducing their efficiency.
The device according to Figure 2 shows another handicap, in so far as the refractory-steel sheath 68 is only extending to the limit of the cylindrical part of the ball-part 58. The refractory tip of the ball-part 58 is, therefore, rapidly overladen with micro-cracks which are at the origin of a rapid wear and a breaking of the tip of the ball-part. The lack of support for the refractory of the tip of the ball-part 58 needs, furthermore, a relatively large radius of curvature R to avoid that the convex tip, which is not supported by the sheath 68, has been tapered too much. This, an its turn, is at the origin of the sharp edge between the cylindrical part and the convex part of the ball-part 58, and which risks to crush the seal 64 during the angular movements of the articulation.
Figures 3 and 3a show each one half of an articulation according to the present invention, the Figures being shown close to each other, so as to show an entire joint, of which the left part shows the version with the ball-part separated from the central conduit segment and of which the right part shows the ball-part being part of the central conduit segment.
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The Figures 3 and 3a show that the ball-part of the articulation according to the present invention 70, 70a is completely envelopped by its refractory-steel sheath 72, 72a, which extends to the base of the ball-part around its convex section. The manufacture of such a refractory sheath 72, 72a, in a single piece with a convex section is rendered possible by an artful manufacturing process, explained more in detail hereinafter. Compared to the state of the art exemplified in Figure 2, the ball-part of the present invention has a less important radius of curvature, in the order of magnitude of half a diameter of the connection conduit segments of the tuyere-stock, which improves its mobility. A seal 74, for example made of ceramic fibers, is provided between the ball-part 70, 70a and the refractory of the tubular connection piece 76. This seal can, for example, be cemented to the armouring of the tubular connection piece 76 between two support rings 78, 80. The seal 74 adapts perfectly to the shape of the tip of the ball-part and extends to the major part of the convex section of the latter. In case the tuyere-stock is designed to accomodate to a maximum axial misalignement of 7°, the ball-part 72, 71 can deviate of 3,5° on both sides from its neutral position illustrated on the Figures 3 and 3a by the angles a and 13. During such an extreme pivoting movement, the seal 74 always forms a thick sealing pad or cushion without being compressed by the ball-part 70, 70a, owing to the tact that the width of the slot or grap remains constant during the relative swivelling.
With reference to Figure 4, the process according to the present invention for making the refractory-steel sheath of a ball-part, will now be described. To this effect, a cylindrical pipe 82 made of refractory steel is used, which might be provided with a small peripheral flange 84, in the case of the embodiment shown in Figure 3.
All around the opposite side of the flange 84, at regular distances, cuttings following the generating line are made, with a depth corresponding to the length of the convex section of the ball-part to be made. These cuttings 86 thus define identical tongues 88. These tongues 88 are then folded down towards the axis of the pipe 82 until the cuttings 86 are completely closed, in order to define a spherical dome with a central opening 90 formed by the frontal bevels 92 of the tongues 88 juxtaposed to each other. This crimping of the tongues 88 can be carried out in a mould with a spherical bottom. The sheath 72 is then finished by welding the different tongues 88 one to the other over the whole length of the cuttings.
Figure 5 illustrates a first embodiment of the oblique section of a tuyere-stack with two identical ball-and socket joints 94 and 96, each of which comprising a ball part enveloped by a sheath made of refractory steel manufactured according to the process described with reference to Figure 4. Figure 5 as well as the following Figures do not show, for reasons of simplicity, the means for obtaining mechanical stability to the joints 94 and 96.
These means, although present in a specific embodiment, can be means known per se, like cardan- joints or tension rods as disclosed in the European Patent EP-A1-0363576.
Figure 5a shows an alternative embodiment already described hereinbefore, according to which the ball-part of the lower joint 96a is separated from the central tubular conduit element 98a.
In both the embodiments of Figures 5 and 5a the sealed connection between the central element 98 and the lower tubular connection piece 100 is performed by means of a flange 102 at the upper end of the sheath of the ball-part.
The central element 98 comprises also an upper flange 104 beyond the expansion joint of the upper articulation 94 to conect the tuyere-stock to the bustle pipe (not shown).
In the embodiment of Figure 5 these flanges 102 and 104 are, moreover, necessary for manufacturing the three S
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elements separately, namely the central element 98, the lower connection piece 100 and the upper connection piece 106, which consists simply of the ball-part of the ball-and-socket joint 94. This manufacturing will now be described and illustrated with reference to Figures 6a, 6b and 6c.
Figure 6a shows the manufacturing of the refractory of the ball-part 106. For this purpose, the sheath 72 manufactured according to the process described with reference to Figure 4, is overturned onto a support 108, made for example of wood, the central opening 90, preferably directed downwards. A cylindrical form 110, made for example of expanded synthetic material, is then introduced into the sheath 72 and hold in place, for example, by a plug 112 fastened to the support 108 and penetrating into an axial channel of the form 110. The only thing that remains to be done is casting the refractory material 114 into the annular space delimited by the form 110 and the sheath 72, by using the latter as a mould.
Figure 6b shows the manufacturing of the central conduit element 98. For this purpose, the assembly formed by the armouring 116 of the central element with the sheath of the lower ball-part and the upper expansion joint is overturned, the flange 104 to the bottom, onto a support 118; the ring 120 which delimits the placement of the joint of the upper articulation 94 closing the opening around the support. The upper profile of the support 118 is complementary to the form of the socket of the articulation 94. Thereupon a cylindrical form 122 made of expanded synthetic material is axially placed onto the support 118, and held in place by a plug 124. The only thing that remains to be done is to fill the annular space around the form 122 with refractory material.
Figure 6c shows the manufacturing of the lower connection piece. As in the case of Figure 6b, the armouring 126 of this tubular connection piece, including ~w~~~~i~~~
the expansion joint of the lower articulation, is overturned, the upper flange to the bottom, onto a support 128 identical to the support 118 used previously.
Then a form made of expanded synthetic material 130, of which the outer form corresponds to the inner channel of the finished tubular connection piece 100, is placed axially onto the support 128, and the space around the form 730 is filled with refractory material. It shall be noted that the three forms made of synthetic material 110, 122 and 130 may remain in place when assembling the tuyere-stock, since they will be consumed automatically when the tuyere-stock is put into operation.
Figure 7 shows a second embodiment of a tuyere-stock with a central tubular element 132, a lower connection piece 134 and a ball-part 136, however, unlike the embodiment of Figure 5, the armouring of the central element 132 is connected by means of the expansion joint of the lower articulation to the armouring of the tubular connection piece 134. The flange 102 of the embodiment of Figure 5a consequently disappeared, which allows a reduction of the manufacturing costs of the tuyere-stock.
On the other hand, since the tubular connection piece 134 cannot be separated from the central element 132, the manufacturing step shown by Figure 6c is no more possible and other ingenious methods have to be employed in order to be able to cast the socket of the lower joint. To this effect, the refractory of the connection piece 134 is cast, in the example shown, in two successive operations, symbolized by the interruption 138. This will also affect the design of the lower joint, particular of the socket of the tubular connection piece 134. Figures 8 and 9 show several embodiments.
Figure 8 shows the details of the ball-and-socket joint 140 between the central element 132 and the lower connection piece 134. The ball-part 142 is identical with the one of the previous embodiment, that is, provided with !'~ S~ ", a refractory sheath made according to Figure 4. On the other hand, the socket 144 of the articulation 140 formed by the upper part of the refractory lining of the connection piece 134 is modified. In fact, as shown in Figure 8, the refractory lining forming the socket 144 is cast inside the cylindrical sheath 146 made of refractory steel and fitted coaxially inside the metal armouring of the tubular connection piece 134. The sheath 146 can be held in place by means of two rings 148 and 150 fixed respecti~rely to the inner wall of the armouring and to the outer wall of the sleeve 146. The thermal insulation is obtained by means of a thick seal 152 made of ceramic fibers which is cemented to the inner surface of the armouring of the connection piece 134 and extends to the bottom between the ball-part 142 and the socket 144. Two annular supports 154 and 156, which are welded to the armouring or housing, ensure the support of the seal.
In the alternative embodiment according to Figure 9, the socket 144 is also arranged inside a sheath 158 made of refractory steel, which compared to the embodiment of Figure 8 is longer than the sheath 146. The part of the sheath 158 which exceeds the refractory lining, is designed as a housing for the seal 160 made of ceramic fibers. The embodiment of Figure 9 in relation to that of Figure 8, has the advantage that the seal 160 can be put in place before assembling the tuyere-stock, and can be inserted together with the socket 144. On the other hand, the embodiment of Figure 8, compared to that of Figure 9, has the advantage of a better thermal insulation because of a seal 152 that is thicker than the seal 160.
Figure 9a shows a compromise solution between the embodiments of Figures 8 and 9 in that the sheath 162 is also used as a housing for the seal 164, but is associated with an annular collar 160, which is welded to the inner surface of the armouring. The seal 164 can thus also be put in place onto the socket before assembling of the tuyere-~~ r.-~' ~a~ rl stack, as is the case in Figure 9, but unlike the latter the collar 166 forms a thermal b:cidge contributing to the heat dissipation from the seal 164 to the outer armouring.
With reference to Figures 10a, 10b and 10c, the manufacturing steps of the different elements of the tuyere-stock of Figure 7 will now be described, as it has been done previously with Figure 5, by also refering to Figures 6a to 6c. By way of example, it will be referred to the use of the embodiment shown in Figure 9.
Figure 10a shows the casting of the refractory into a sheath according to Figure 4 to make the upper ball-part 136. This step is identical to the one described with reference to Figure 6a and does not have to be explained further.
At this instant however the intermediary step illustrated in Figure 10b is applied. This Figure shows the separated casting of the socket 144 of the lower articulation joint 140. First, the sheath 158 is placed onto a mould 168 made of wood, the housing provided far the seal 160 (Figure 9) being directed to the bottom. The profile of the upper front of this mould 168 is .complementary to that of the refractory lining of the socket 144. Then a form 169 made of expanded synthetic material corresponding to the opening of the socket 144 is placed axially inside the sheath 158 onto the support 168, and the refractory material is cast between this form 169 and the sheath 158. Following the casting and the removal of the mould 168, the seal 160 (Figure 9) can be cemented in its housing inside the sheath 158.
With a view to the casting of the central element 132, its metal armouring which is fixed to that of the connection piece 134 by means of the expansion joint, is overturned onto the upper flange. The casting itself of the element 132 is identical to the casting described with reference to Figure 6b, and the same moulds and forms will be used. When this casting is completed, the socket 144 s~ ~ .> j ,~
cast as explained with reference to Figure 10b and after the seal has been put in place, is introduced into the armouring of the connection piece 134 in order to place it on the ball-part 142 where it is held by the abutments 148 5 and 150. When the socket 144 is in place a form, not shown, defining the channel of the tubular connection piece 134, is placed on this socket 144, and the casting of the connection piece 134 is finished by filling the annular space between said form and the armouring of the tubular 10 connection piece 134 with refractory material.
Figure 11 shows a third embodiment similar to the one shown in Figure 7 which comprises a central tubular conduit element 170 connected through an upper ball-and-socket articulation 176 to a ball-part 172 and thourgh a Lower 15 ball-and-socket articulation 178 to a tubular connection piece 174. The lower connection piece 174 and the lower articulation 178 are identical with the embodiment of Figure 5 and, thus, do not have to be described further.
The central element 170 is analogous to the one of the embodiment of Figure 7 insofar as it does not comprise a flange for its connection to the tubular connection piece 174. In order to solve, in the embodiment of Figure 11, the manufacturing and assembly problems as explained with reference to Figure 7, a removable or detachable link or connecting piece is provided between the armouring of the central element 170 and that of the tubular connection piece 174. As shown by Figure 11, an upper end 180 of the expansion joint 182 is welded to the armouring of the central conduit element 170 through a metallic shoulder member 184 onto which is also welded the sheath of the ball-part of articulation 178. The solidity of the welding of the member 180 to the shoulder 184 must be a compromise between the necessity to be able to remove the welding in case of dismounting, on the one hand, and the necessity to ensure the sealing and to restrain the internal pressure, on the other hand.
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The embodiment of Figure 11 has the advantage of the same simplicity in manufacture as the embodiment of Figure 5, that as, there is no need to cast the lower connection piece in two steps, and it also has the advantage the advantage of the embodiment of Figure 7, to save the linking flange between the central element and the lower connection piece. However, the embodiment of Figure 11 needs a welding that must resist the internal pressure.
The different casting steps of the elements of the embodiment of Figure 11 as illustrated by Figures 12a, 12b and 12c, correspond exactly to those disclosed with reference to Figures 6a, 6b and 6c, and thus do not have to be explained further; the same forms and moulds being used.
The only difference lies in the absence of a flange on the connecting element 180 of the expansion joint 182 and in the absence of a flange on the central element 170, which is replaced by shoulder 184. Following the casting of the three elements 170, 172 and 174 according to Figures 12a, 12b and 12c, the seal of the lower articulation 178 is put in place by cementing it to the housing provided at the inner surface of the armouring of the connection piece 174 above the expansion joint 182.
Then the connection piece 174 is attached to the ball-part of the central element 170 and the peripheral welding between the connecting element 180 and the shoulder 184 is made.
With reference to Figure 13 a fourth embodiment will now be described, which combines all the advantages of the three previous embodiments. The embodiment according to Figure 13 also comprises a central tubular element 200 connected through an upper ball-and-socket joint to a ball-part 202 and through a lower ball-and-socket joint 208 to a lower connection piece 204. However, contrary to the previous embodiments, the two sockets of the articulations 206 and 208 are provided at opposite ends of r. :~ r~ s, ....
r> 'J 'l i.j ~~
the central element 200, the ball-part of the lower articulation 208 forming a part of the connection piece 204. The upper and lower articulations are thus positioned in opposite directions, as disclosed in the European Patent EP-A1-0363576, which also gives the advantages described in this document.
As shown in Figure 13, this embodiment saves the flange of the central element 200, without having to provide a removable weld between the armouring of the latter and the armouring of the lower connection piece 204 and without having to cast the tubular connection piece 204 in two steps as indicated in the description of the different manufacturing steps, which will be described hereinafter with reference to Figures 13a, 13b and 13c.
The manufacture of the ball-part 202 illustrated by Figure 13a is in accordance with the manufacture of the ball-parts of the previous embodiments.
Figure 13b shows the manufacture of the central element 200. The metal armouring of the element 200, which makes part of the one of the lower tubular connection piece 204, is placed onto a mould made of wood which holds it through the housing of the seal of the lower articulation 208. The mould 210 is supported by a base 212 which is, preferably, provided with a base element supporting, the armouring of the connection piece 204 through an inner stop 216 which will thereafter serve as a fixing support for the sheath of the ball-part. The profile of the upper front of the mould 210 is complementary to that of the socket of the lower articulation Thus, a form 218 made of expanded synthetic material and corresponding to the inner channel of the central element 200, has merely to be placed axially inside the armouring of the element 200 and on the mould 210. Then the annular space between the form 218 and the armouring has to be filled to the brim of the housing of the seal of the upper articulation 206. The profile of the socket 220 of the upper articulation is formed in the cast refractory material by removing the cast material before it hardens, for example with a strickle having a profile complementary to the one of the socket 220. The structure thus made in accordance with Figure 13b is then turned over and placed on a base 222 which consists preferably of a mould made of wood used to model the socket of the articulations. The structure is carried by the socket 220 on the mould 222.
The seal 224 is subsequently put in place by cementing it in its housing provided to this effect on the inner surface of the armouring of the element 200. A disc 226 made of expanded synthetic material is then placed at the bottom of the socket-part previously formed by the mould 210 in Figure 13b, the thickness of the disc corresponding to the axial width of the transverse slot of the articulation 208 between its ball-part and socket. The sheath of ball-part 72 is then introduced from above into the armouring of the connection piece 204 by placing it and welding it by its edge 84 onto the stop device 216 provided on the inner surface of the armouring. A form made of expanded synthetic material is then placed axially on the disc 226, the configuration of the form corresponding to the passage channel of the tubular connection piece 204.
All that needs to be done then is to cast the refractory material into the annular space around that form, by using the sheath 72 as a mould. After the removal of the mould 222 and of the plugs 228 and 330 used to maintain the inner forms during the casting, the central element 200 and the tubular connection piece 204 are ready for assembly, the inner forms as well as the disc 226 can stay in place given that they will be used up automatically when the tuyere-stock is put into operation.
DEVICE FOR INJECTING PREHEATED AIR INTO A SHAFT FURNACE AND
PROCESS FOR MANUFACT~7RING BALL-AND-SOC1KET JOINTS
The present invention relates to a device for injecting preheated air into a shaft furnace, consisting of a plurality of separate cylindrical elements, each consisting of an external steel easing and an internal refractory lining and comprising at least one central tubular element connected, on one side, by a first ball-and-socket articulation and a first expansion joint to an upper connection piece integral with a preheated air feeding bustle pipe surrounding the furnace and, on the other or opposite side, by a second ball-and-socket articulation and a second expansion joint to a lower connection piece extended by an elbow and a blast nozzle, the latter being articulated on a tuyere installed in the wall of the furnace, and in which device the ball-and-socket joints comprise a convex ball-part formed by the end of one of the connection segments and pivoting in a concave socket-part formed by the end of the adjacent connection segment and a soft refractory joint interposed therebetween.
These devices, more generally known under the name of "tuyere-stock", are subject to problems of mobility and sealing. In fact, as a result of high temperature of the preheated air (a temperature of the order of 1200°C or more) and of the high temperature prevailing inside the furnace, the wall of the latter and the bustle pipe and the tuyere-stock are subject to thermal expansions and deformations which cause significant relative displacements between the bustle pipe and the wall of the furnace. The tuyere-stock must therefore be capable of compensating for these relative displacements, whilst at the same time preventing leaks of gas or preheated air.
To meet these requirements, US Patent 3,766,868 provides a tuyere-stock of the type described in the introduction. This tuyere-stock has since been improved by the design of universal ball-and-socket joints like those d U
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z described in the German patent specification DE-C2-2218331.
The three joints of this tuyere-stock make it passible to compensate all the relative movements between the bustle pipe and the wall of the furnace. Sealing in the region of the joints is obtained by means of bellows expansion joints, whilst mechanical stability is ensured by means of cardan connections associated with the two opposite ends of the central tubular element in the region of the two universal joints.
The most stressed and most critical part is always located in the place of the joints . In fact, the mobility of the ball-part with respect to its socket often leads to irreversible distortions of the soft joints and to frictions among refractory materials. In addition, given the difficulties to machine refractory steel, it is not possible to extend the armouring, forming the casing of the ball-part, to the tip of the latter. That is the main reason why microcracks are often formed in the refractory of the tip of the ball-part, causing disturbing circulations and whirls.
To these quality criteria of a reliable tuyere-stock are added the concern for a competitive manufacturing price, for the possibility of easy and rapid dismounting, for the possibility to easily renew the refractory material if necessary, etc. It is obvious that all those criteria often tend to oppose each other, thus forcing the designer and manufacturer to choose a reasonable compromise.
The object of the present invention is to provide a new device of the type described in the introduction, which is more resistant to wear at the place of the joints, which owing to its numerous alternative solutions, adapts itself perfectly to the requirements of the user, while permitting a reasonable manufacturing price.
In order to achieve this object, the device according to the present invention is characterized essentially in that the radius of curvature of each ball-and-socket joint ~~J
is in an order of magnitude of half the diameter of the different connection elements and in that the convex ball-parts of the ball-and-socket joints comprise a protective sheath or sleeve made of refractory steel and which extends to the diametrical base of the ball-part. The reduction of the radius of curvature of the ball-and-socket joints allows a better guiding of the ball-parts in their sockets, while reducing the risks of shock and wear of the soft joints by permmitting to keep always the same width for a joint.
The reduction of the radius of curvature of the joints and the fact that the metallic armouring or casing, which at this place, forms the sheath of the ball and extends to the base of the latter, allows to maintain a uniform width of the joint slot or groove during the pivotments.
The present invention also provides a new process for manufacturing a convex ball-part of ball-and-socket joints of a device far injecting preheated air into a shaft furnace, said process consisting in first fabricating the ball sheath or sleeve of refractory steel and to provide it with an inner refractory lining, and being characterized in that the end of a refractory steel pipe is distorted until it has the form of a convex dome with a central opening and a convex spherical surface extending between the central opening and the cylindrical surface of the pipe, in that the sheath thus formed is placed on a support, in that a cylinder having a diameter slightly inferior to the diameter of said central opening, is placed axially inside, and in that refractory material is cast between the cylinder and said sheath by using the latter as a mould.
According to a first embodiment of a tuyere-stock according to the invention, the ball-parts are formed by the lower ends of the upper connection element and of the central tubular element.
w ~~ )>~J,~~3 The ball--part of the central tubular element can either be an integral part of this element, or be separated from the latter by a transverse junction filled with an annular joint.
The armouring of the central tubular element and the one of the lower connection pipe can be connected directly to each other through an expansion joint, or by means of a flange or an detachable weld.
The socket of the lower joint can be formed into the refractory lining cast in a cylindrical sheath made of refractory steel and arranged coaxially inside the armouring of the lower connection piece.
The soft refractory joint can be fixed partially to the armouring and partially to the rim of the socket. It can also be partially fixed to an inner seat of the cylindrical sheath and partially to the refractory material.
Alternatively, it can also be attached partially to the refractory material and partially to a seat delimited by the upper part of the sheath and by a ring welded inside the armouring.
According to a second embodiment, the sockets of both ball-and-socket joints are arranged at the two opposite ends of the central tubular element, whilst the convex ball-parts are arranged in the upper and lower connection pieces.
Other particular features and adavantages of the invention will be appreciated and understood by those skilled in the art from the following detailed description of several embodiments, with reference to the accompanying drawings in which:
- Figure 1 shows a view, in vertical section, of a conventional foyers-stock according to US Patent 3,766,867;
- Figure 1a shows an alternative embodiment of the lower joint of the tuyere-stock according to Figure 1;
- Figure 2 shows the details of a joint of a tuyere-stock as disclosed in German Patent DE-C2-2218331;
- Figures 3 and 3a illustrate in juxtaposition and in axial section a ball-and-socket joint according to the present invention;
- Figure 4 illustrates schematically the process making a sheath of refractory steel, for a ball-part of a joint connection according to the present invention;
Figure 5 shows diagrammatically an axial section through the vertical section of a first embodiment of a tuyere-stock according to the present invention;
- Figure 5a illustrates schematically an alternate execution of the lower joint of the tuyere-stock according to Figure 5;
- Figures 6a, 6b and 6c illustrate schematically the different manufacturing steps of the refractory lining of the different elements of the tuyere-stock depicted in Figure 5;
- Figure 7 is a similar view to that of Figure 5 of a second embodiment of a tuyere-stock according to the present invention;
- Figures 8, 9 and 9a illustrate different alternate embodiments of the lower joint connection of the tuyere-stock according to Figure 7;
- Figures 10a, 10b and 10c illustrate schematically the different manufacturing steps of the refractory lining of the different elements of the tuyere-stock depicted in Figure 7;
- Figure 11 illustrates schematically a third embodiment of a tuyere-stock according to the present invention;
- Figures 12a, 12b et 12c illustrate schematically the different manufacturing steps of the refractory lining of the tuyere-stock depicted in Figure 11;
- Figure 13 illustrates schematically a fourth embodiment of a tuyere-stock according to the present invention and :~ , s~ -.
~~'~~r~~W3 - Figures 13a, 13b and 13c illustrate schematically the different manufacturing steps of the refractory lining of the tuyere-stock depicted in Figure 13.
The known tuyere-stock, designated by the reference 20 in Figure 1, connects a main bustle pipe 22, arranged around a blast furnace, to the wall 24 of the blast furnace. This tuyere-stock 20 comprises a straight oblique section consisting of a central tubular element 26 articulated with its upper end on a connection piece 28 fixed to the bustle pipe 22 and at its lower end on a connection piece 30 flanged to an elbow 32. This elbow 32 is extended by a nozzle 34, the end of which is articulated on a tuyere 36 fastened in the wall 24 of the furnace. The upper joints 38 and lower joints 40 between the central tubular element 26 and the two connection pieces 28 and 30 are universal joints allowing relative shifts or movements between the bustle pipe 22 and the wall of the furnace 24.
Sealing in the region of the joints 38 and 40 is obtained by means of bellows expansion joints 44, 46 fixed respectively to the tubular element 26 and the adjacent connection pieces 28 and 30. Mechanical stability is ensured by means of cardan joints 48, 50 likewise connecting the central element 26 to the adjacent connection pieces 28 and 30. All these elements of the tuyere-stock consist of an outer-metal armouring or housing 52 provided with an inner refractory lining 54, through which passes a supply channel or conduit 56 ensuring the passage of the preheated air.
each one of the two joints 38, 40 consists of a convex part called ball and of a concave part called socket. In the upper joint 38, the ball is part of the upper connection piece 28 and penetrates into the socket formed by the upper end of the central element 26. The lower part of the latter constitutes the ball-part of joint 40 and penetrates into the socket formed by the upper part of the lower connection piece 40.
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In the embodiment of Figure 1, the ball-part of the joint 40 is integral with the central element 26, that is, its refractory lining extends, without interruption, from the upper end to the tip of the ball-part. This design of the central element 26 makes its manufacture easier, compared with the alternative solution illustrated in Figure 1a, where the ball-part is separated from the rest of the central element and is connected to the latter in the region of the flange, which is provided for the , fastening of the cardan 50a. The alternative solution illustrated on figure 1a presents however the advantage of allowing the separate dismounting of the lower part, which consists of the tubular connection piece 30 and the joint 40a, from the upper part consisting of the rest of the central element 26 and the upper joint 38 with the tubular connection piece 28. It shall be noted that the upper joint 38 must necessarily be designed as shown in Figure 1a, so that the tuyere-stock can be disconnected from the bustle pipe 22.
Figure 2 shows a known embodiment of a joint connection as disclosed in the German patent DE-C2-2218331. This embodiment is different essentially from that one depicted in Figure 1 in that the joints are spherical, as shown by the joint between the ball part 58 and the socket of the connection piece 30. In this embodiment, the ball-part 58 is also separated from the central element 26, following the example of Figure 1a. The embodiment according to Figure 1 is, nevertheless, also feasable here.
Another difference as compared with the embodiment of Figure 1 is the arrangement of soft resilient joints in the region of the ball-and-socket joint. A first sealing ring 62 consisting, for example, of ceramic fibers is incorporated in the refractory of the socket 60 and closes the pasage way between the socket 60 and the tip of the ball-part 58. Another soft seal 64, also made of ceramic fibers, is arranged in the annular space between the lower ~~J'?3 end of the metallic sheath 68 of the ball-part 58 and the cylindrical connection sleeve of the expansion joint 44.
This seal 64 is wedged between the edge of the socket 60 and a peripheral collar 66 welded to the sheath 68.
The purpose of these joints 62 and 64 is essentially to stop or to reduce the penetration of hot air inside the expansion joints 44 in order to provide them a better protection against high temperatures. when the ball-part 58 is subjected to an axial shift relative to the connection piece 30, the lower edge of the sheath 68 may distort or even crush the seal 64 on one side, whereas on the opposite side, the collar 66 tends to compress the seal 64 in the axial direction. Given that the refractory joints are lacking elasticity, there is a risk that these shifts cause irreversible distortions, thus reducing their efficiency.
The device according to Figure 2 shows another handicap, in so far as the refractory-steel sheath 68 is only extending to the limit of the cylindrical part of the ball-part 58. The refractory tip of the ball-part 58 is, therefore, rapidly overladen with micro-cracks which are at the origin of a rapid wear and a breaking of the tip of the ball-part. The lack of support for the refractory of the tip of the ball-part 58 needs, furthermore, a relatively large radius of curvature R to avoid that the convex tip, which is not supported by the sheath 68, has been tapered too much. This, an its turn, is at the origin of the sharp edge between the cylindrical part and the convex part of the ball-part 58, and which risks to crush the seal 64 during the angular movements of the articulation.
Figures 3 and 3a show each one half of an articulation according to the present invention, the Figures being shown close to each other, so as to show an entire joint, of which the left part shows the version with the ball-part separated from the central conduit segment and of which the right part shows the ball-part being part of the central conduit segment.
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The Figures 3 and 3a show that the ball-part of the articulation according to the present invention 70, 70a is completely envelopped by its refractory-steel sheath 72, 72a, which extends to the base of the ball-part around its convex section. The manufacture of such a refractory sheath 72, 72a, in a single piece with a convex section is rendered possible by an artful manufacturing process, explained more in detail hereinafter. Compared to the state of the art exemplified in Figure 2, the ball-part of the present invention has a less important radius of curvature, in the order of magnitude of half a diameter of the connection conduit segments of the tuyere-stock, which improves its mobility. A seal 74, for example made of ceramic fibers, is provided between the ball-part 70, 70a and the refractory of the tubular connection piece 76. This seal can, for example, be cemented to the armouring of the tubular connection piece 76 between two support rings 78, 80. The seal 74 adapts perfectly to the shape of the tip of the ball-part and extends to the major part of the convex section of the latter. In case the tuyere-stock is designed to accomodate to a maximum axial misalignement of 7°, the ball-part 72, 71 can deviate of 3,5° on both sides from its neutral position illustrated on the Figures 3 and 3a by the angles a and 13. During such an extreme pivoting movement, the seal 74 always forms a thick sealing pad or cushion without being compressed by the ball-part 70, 70a, owing to the tact that the width of the slot or grap remains constant during the relative swivelling.
With reference to Figure 4, the process according to the present invention for making the refractory-steel sheath of a ball-part, will now be described. To this effect, a cylindrical pipe 82 made of refractory steel is used, which might be provided with a small peripheral flange 84, in the case of the embodiment shown in Figure 3.
All around the opposite side of the flange 84, at regular distances, cuttings following the generating line are made, with a depth corresponding to the length of the convex section of the ball-part to be made. These cuttings 86 thus define identical tongues 88. These tongues 88 are then folded down towards the axis of the pipe 82 until the cuttings 86 are completely closed, in order to define a spherical dome with a central opening 90 formed by the frontal bevels 92 of the tongues 88 juxtaposed to each other. This crimping of the tongues 88 can be carried out in a mould with a spherical bottom. The sheath 72 is then finished by welding the different tongues 88 one to the other over the whole length of the cuttings.
Figure 5 illustrates a first embodiment of the oblique section of a tuyere-stack with two identical ball-and socket joints 94 and 96, each of which comprising a ball part enveloped by a sheath made of refractory steel manufactured according to the process described with reference to Figure 4. Figure 5 as well as the following Figures do not show, for reasons of simplicity, the means for obtaining mechanical stability to the joints 94 and 96.
These means, although present in a specific embodiment, can be means known per se, like cardan- joints or tension rods as disclosed in the European Patent EP-A1-0363576.
Figure 5a shows an alternative embodiment already described hereinbefore, according to which the ball-part of the lower joint 96a is separated from the central tubular conduit element 98a.
In both the embodiments of Figures 5 and 5a the sealed connection between the central element 98 and the lower tubular connection piece 100 is performed by means of a flange 102 at the upper end of the sheath of the ball-part.
The central element 98 comprises also an upper flange 104 beyond the expansion joint of the upper articulation 94 to conect the tuyere-stock to the bustle pipe (not shown).
In the embodiment of Figure 5 these flanges 102 and 104 are, moreover, necessary for manufacturing the three S
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elements separately, namely the central element 98, the lower connection piece 100 and the upper connection piece 106, which consists simply of the ball-part of the ball-and-socket joint 94. This manufacturing will now be described and illustrated with reference to Figures 6a, 6b and 6c.
Figure 6a shows the manufacturing of the refractory of the ball-part 106. For this purpose, the sheath 72 manufactured according to the process described with reference to Figure 4, is overturned onto a support 108, made for example of wood, the central opening 90, preferably directed downwards. A cylindrical form 110, made for example of expanded synthetic material, is then introduced into the sheath 72 and hold in place, for example, by a plug 112 fastened to the support 108 and penetrating into an axial channel of the form 110. The only thing that remains to be done is casting the refractory material 114 into the annular space delimited by the form 110 and the sheath 72, by using the latter as a mould.
Figure 6b shows the manufacturing of the central conduit element 98. For this purpose, the assembly formed by the armouring 116 of the central element with the sheath of the lower ball-part and the upper expansion joint is overturned, the flange 104 to the bottom, onto a support 118; the ring 120 which delimits the placement of the joint of the upper articulation 94 closing the opening around the support. The upper profile of the support 118 is complementary to the form of the socket of the articulation 94. Thereupon a cylindrical form 122 made of expanded synthetic material is axially placed onto the support 118, and held in place by a plug 124. The only thing that remains to be done is to fill the annular space around the form 122 with refractory material.
Figure 6c shows the manufacturing of the lower connection piece. As in the case of Figure 6b, the armouring 126 of this tubular connection piece, including ~w~~~~i~~~
the expansion joint of the lower articulation, is overturned, the upper flange to the bottom, onto a support 128 identical to the support 118 used previously.
Then a form made of expanded synthetic material 130, of which the outer form corresponds to the inner channel of the finished tubular connection piece 100, is placed axially onto the support 128, and the space around the form 730 is filled with refractory material. It shall be noted that the three forms made of synthetic material 110, 122 and 130 may remain in place when assembling the tuyere-stock, since they will be consumed automatically when the tuyere-stock is put into operation.
Figure 7 shows a second embodiment of a tuyere-stock with a central tubular element 132, a lower connection piece 134 and a ball-part 136, however, unlike the embodiment of Figure 5, the armouring of the central element 132 is connected by means of the expansion joint of the lower articulation to the armouring of the tubular connection piece 134. The flange 102 of the embodiment of Figure 5a consequently disappeared, which allows a reduction of the manufacturing costs of the tuyere-stock.
On the other hand, since the tubular connection piece 134 cannot be separated from the central element 132, the manufacturing step shown by Figure 6c is no more possible and other ingenious methods have to be employed in order to be able to cast the socket of the lower joint. To this effect, the refractory of the connection piece 134 is cast, in the example shown, in two successive operations, symbolized by the interruption 138. This will also affect the design of the lower joint, particular of the socket of the tubular connection piece 134. Figures 8 and 9 show several embodiments.
Figure 8 shows the details of the ball-and-socket joint 140 between the central element 132 and the lower connection piece 134. The ball-part 142 is identical with the one of the previous embodiment, that is, provided with !'~ S~ ", a refractory sheath made according to Figure 4. On the other hand, the socket 144 of the articulation 140 formed by the upper part of the refractory lining of the connection piece 134 is modified. In fact, as shown in Figure 8, the refractory lining forming the socket 144 is cast inside the cylindrical sheath 146 made of refractory steel and fitted coaxially inside the metal armouring of the tubular connection piece 134. The sheath 146 can be held in place by means of two rings 148 and 150 fixed respecti~rely to the inner wall of the armouring and to the outer wall of the sleeve 146. The thermal insulation is obtained by means of a thick seal 152 made of ceramic fibers which is cemented to the inner surface of the armouring of the connection piece 134 and extends to the bottom between the ball-part 142 and the socket 144. Two annular supports 154 and 156, which are welded to the armouring or housing, ensure the support of the seal.
In the alternative embodiment according to Figure 9, the socket 144 is also arranged inside a sheath 158 made of refractory steel, which compared to the embodiment of Figure 8 is longer than the sheath 146. The part of the sheath 158 which exceeds the refractory lining, is designed as a housing for the seal 160 made of ceramic fibers. The embodiment of Figure 9 in relation to that of Figure 8, has the advantage that the seal 160 can be put in place before assembling the tuyere-stock, and can be inserted together with the socket 144. On the other hand, the embodiment of Figure 8, compared to that of Figure 9, has the advantage of a better thermal insulation because of a seal 152 that is thicker than the seal 160.
Figure 9a shows a compromise solution between the embodiments of Figures 8 and 9 in that the sheath 162 is also used as a housing for the seal 164, but is associated with an annular collar 160, which is welded to the inner surface of the armouring. The seal 164 can thus also be put in place onto the socket before assembling of the tuyere-~~ r.-~' ~a~ rl stack, as is the case in Figure 9, but unlike the latter the collar 166 forms a thermal b:cidge contributing to the heat dissipation from the seal 164 to the outer armouring.
With reference to Figures 10a, 10b and 10c, the manufacturing steps of the different elements of the tuyere-stock of Figure 7 will now be described, as it has been done previously with Figure 5, by also refering to Figures 6a to 6c. By way of example, it will be referred to the use of the embodiment shown in Figure 9.
Figure 10a shows the casting of the refractory into a sheath according to Figure 4 to make the upper ball-part 136. This step is identical to the one described with reference to Figure 6a and does not have to be explained further.
At this instant however the intermediary step illustrated in Figure 10b is applied. This Figure shows the separated casting of the socket 144 of the lower articulation joint 140. First, the sheath 158 is placed onto a mould 168 made of wood, the housing provided far the seal 160 (Figure 9) being directed to the bottom. The profile of the upper front of this mould 168 is .complementary to that of the refractory lining of the socket 144. Then a form 169 made of expanded synthetic material corresponding to the opening of the socket 144 is placed axially inside the sheath 158 onto the support 168, and the refractory material is cast between this form 169 and the sheath 158. Following the casting and the removal of the mould 168, the seal 160 (Figure 9) can be cemented in its housing inside the sheath 158.
With a view to the casting of the central element 132, its metal armouring which is fixed to that of the connection piece 134 by means of the expansion joint, is overturned onto the upper flange. The casting itself of the element 132 is identical to the casting described with reference to Figure 6b, and the same moulds and forms will be used. When this casting is completed, the socket 144 s~ ~ .> j ,~
cast as explained with reference to Figure 10b and after the seal has been put in place, is introduced into the armouring of the connection piece 134 in order to place it on the ball-part 142 where it is held by the abutments 148 5 and 150. When the socket 144 is in place a form, not shown, defining the channel of the tubular connection piece 134, is placed on this socket 144, and the casting of the connection piece 134 is finished by filling the annular space between said form and the armouring of the tubular 10 connection piece 134 with refractory material.
Figure 11 shows a third embodiment similar to the one shown in Figure 7 which comprises a central tubular conduit element 170 connected through an upper ball-and-socket articulation 176 to a ball-part 172 and thourgh a Lower 15 ball-and-socket articulation 178 to a tubular connection piece 174. The lower connection piece 174 and the lower articulation 178 are identical with the embodiment of Figure 5 and, thus, do not have to be described further.
The central element 170 is analogous to the one of the embodiment of Figure 7 insofar as it does not comprise a flange for its connection to the tubular connection piece 174. In order to solve, in the embodiment of Figure 11, the manufacturing and assembly problems as explained with reference to Figure 7, a removable or detachable link or connecting piece is provided between the armouring of the central element 170 and that of the tubular connection piece 174. As shown by Figure 11, an upper end 180 of the expansion joint 182 is welded to the armouring of the central conduit element 170 through a metallic shoulder member 184 onto which is also welded the sheath of the ball-part of articulation 178. The solidity of the welding of the member 180 to the shoulder 184 must be a compromise between the necessity to be able to remove the welding in case of dismounting, on the one hand, and the necessity to ensure the sealing and to restrain the internal pressure, on the other hand.
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The embodiment of Figure 11 has the advantage of the same simplicity in manufacture as the embodiment of Figure 5, that as, there is no need to cast the lower connection piece in two steps, and it also has the advantage the advantage of the embodiment of Figure 7, to save the linking flange between the central element and the lower connection piece. However, the embodiment of Figure 11 needs a welding that must resist the internal pressure.
The different casting steps of the elements of the embodiment of Figure 11 as illustrated by Figures 12a, 12b and 12c, correspond exactly to those disclosed with reference to Figures 6a, 6b and 6c, and thus do not have to be explained further; the same forms and moulds being used.
The only difference lies in the absence of a flange on the connecting element 180 of the expansion joint 182 and in the absence of a flange on the central element 170, which is replaced by shoulder 184. Following the casting of the three elements 170, 172 and 174 according to Figures 12a, 12b and 12c, the seal of the lower articulation 178 is put in place by cementing it to the housing provided at the inner surface of the armouring of the connection piece 174 above the expansion joint 182.
Then the connection piece 174 is attached to the ball-part of the central element 170 and the peripheral welding between the connecting element 180 and the shoulder 184 is made.
With reference to Figure 13 a fourth embodiment will now be described, which combines all the advantages of the three previous embodiments. The embodiment according to Figure 13 also comprises a central tubular element 200 connected through an upper ball-and-socket joint to a ball-part 202 and through a lower ball-and-socket joint 208 to a lower connection piece 204. However, contrary to the previous embodiments, the two sockets of the articulations 206 and 208 are provided at opposite ends of r. :~ r~ s, ....
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the central element 200, the ball-part of the lower articulation 208 forming a part of the connection piece 204. The upper and lower articulations are thus positioned in opposite directions, as disclosed in the European Patent EP-A1-0363576, which also gives the advantages described in this document.
As shown in Figure 13, this embodiment saves the flange of the central element 200, without having to provide a removable weld between the armouring of the latter and the armouring of the lower connection piece 204 and without having to cast the tubular connection piece 204 in two steps as indicated in the description of the different manufacturing steps, which will be described hereinafter with reference to Figures 13a, 13b and 13c.
The manufacture of the ball-part 202 illustrated by Figure 13a is in accordance with the manufacture of the ball-parts of the previous embodiments.
Figure 13b shows the manufacture of the central element 200. The metal armouring of the element 200, which makes part of the one of the lower tubular connection piece 204, is placed onto a mould made of wood which holds it through the housing of the seal of the lower articulation 208. The mould 210 is supported by a base 212 which is, preferably, provided with a base element supporting, the armouring of the connection piece 204 through an inner stop 216 which will thereafter serve as a fixing support for the sheath of the ball-part. The profile of the upper front of the mould 210 is complementary to that of the socket of the lower articulation Thus, a form 218 made of expanded synthetic material and corresponding to the inner channel of the central element 200, has merely to be placed axially inside the armouring of the element 200 and on the mould 210. Then the annular space between the form 218 and the armouring has to be filled to the brim of the housing of the seal of the upper articulation 206. The profile of the socket 220 of the upper articulation is formed in the cast refractory material by removing the cast material before it hardens, for example with a strickle having a profile complementary to the one of the socket 220. The structure thus made in accordance with Figure 13b is then turned over and placed on a base 222 which consists preferably of a mould made of wood used to model the socket of the articulations. The structure is carried by the socket 220 on the mould 222.
The seal 224 is subsequently put in place by cementing it in its housing provided to this effect on the inner surface of the armouring of the element 200. A disc 226 made of expanded synthetic material is then placed at the bottom of the socket-part previously formed by the mould 210 in Figure 13b, the thickness of the disc corresponding to the axial width of the transverse slot of the articulation 208 between its ball-part and socket. The sheath of ball-part 72 is then introduced from above into the armouring of the connection piece 204 by placing it and welding it by its edge 84 onto the stop device 216 provided on the inner surface of the armouring. A form made of expanded synthetic material is then placed axially on the disc 226, the configuration of the form corresponding to the passage channel of the tubular connection piece 204.
All that needs to be done then is to cast the refractory material into the annular space around that form, by using the sheath 72 as a mould. After the removal of the mould 222 and of the plugs 228 and 330 used to maintain the inner forms during the casting, the central element 200 and the tubular connection piece 204 are ready for assembly, the inner forms as well as the disc 226 can stay in place given that they will be used up automatically when the tuyere-stock is put into operation.
Claims (14)
1. A device for injecting preheated air into a shaft furnace, comprising:
tubular conduit means for directing the preheated air from an outlet end of an air feeding bustle pipe to the furnace, said conduit means comprising;
at least one central tubular conduit member of a first diameter for directing the preheated air, said central tubular conduit means extending from an inlet end to an outlet end and including a steel outer sheath and a refractory inner lining;
an upstream tubular conduit member of the first diameter, extending from the outlet end of the bustle pipe to an upstream outlet end, said upstream outlet end having a profile complementary to that of the inlet end of the tubular conduit member and including a steel outer sheath and a refractory inner housing, first connector means, comprising a first ball-and-socket joint and a first expansion joint, for connecting the inlet end of the central tubular member to the upstream outlet end;
a downstream tubular conduit member of the first diameter extending from a downstream inlet end, said downstream inlet end having a profile complementary to that of the outlet end of the central tubular member, to the shaft furnace and including a steel outer sheath and a refractory inner lining;
second connector means, comprising a second ball-and-socket joint and a second expansion joint for connecting the outlet end of the central tubular member to the downstream inlet end;
said first and second ball-and-socket joints each including;
a tubular convex ball portion, formed on one of said respective ends to be connected, a tubular concave socket portion, formed on the other of said respective ends to be connected, for pivotably contacting the convex ball portion; and a soft refractory annular insert interposed between the ball portion and the socket portion, wherein each of the ball portions and socket portions exhibits a radius of curvature equal to about half the diameter of the respective tubular conduit members connected by the respective ball-and-socket joints; and wherein each of the convex ball portions includes a steel outer sheath and an inner refractory lining.
tubular conduit means for directing the preheated air from an outlet end of an air feeding bustle pipe to the furnace, said conduit means comprising;
at least one central tubular conduit member of a first diameter for directing the preheated air, said central tubular conduit means extending from an inlet end to an outlet end and including a steel outer sheath and a refractory inner lining;
an upstream tubular conduit member of the first diameter, extending from the outlet end of the bustle pipe to an upstream outlet end, said upstream outlet end having a profile complementary to that of the inlet end of the tubular conduit member and including a steel outer sheath and a refractory inner housing, first connector means, comprising a first ball-and-socket joint and a first expansion joint, for connecting the inlet end of the central tubular member to the upstream outlet end;
a downstream tubular conduit member of the first diameter extending from a downstream inlet end, said downstream inlet end having a profile complementary to that of the outlet end of the central tubular member, to the shaft furnace and including a steel outer sheath and a refractory inner lining;
second connector means, comprising a second ball-and-socket joint and a second expansion joint for connecting the outlet end of the central tubular member to the downstream inlet end;
said first and second ball-and-socket joints each including;
a tubular convex ball portion, formed on one of said respective ends to be connected, a tubular concave socket portion, formed on the other of said respective ends to be connected, for pivotably contacting the convex ball portion; and a soft refractory annular insert interposed between the ball portion and the socket portion, wherein each of the ball portions and socket portions exhibits a radius of curvature equal to about half the diameter of the respective tubular conduit members connected by the respective ball-and-socket joints; and wherein each of the convex ball portions includes a steel outer sheath and an inner refractory lining.
2. The device of claim 1, wherein the respective ball portions are formed at the upstream outlet end and the outlet end of the central tubular conduit member and the respective socket portions are formed at the inlet end of the central tubular conduit member and the downstream inlet end.
3. The device of claim 2, wherein the ball portion at the outlet end central tubular conduit member is an integral part of the central tubular conduit member.
4. The device of claim 2, wherein the ball portion of the central tubular conduit member is separated from the central tubular conduit member by a transverse junction and an interposed annular seal.
5. The device of claim 1, wherein the second connector means includes a flange connected to the expansion joint.
6. The device of claim 1, wherein the steel outer sheath of the central tubular conduit member and the steel outer sheath of the downstream tubular conduit member are directly connected to each other by the second expansion joint.
7. The device of claim 2, wherein the steel outer sheath of the central tubular conduit member and the steel outer sheath of the downstream tubular conduit member are connected to each other by a detachable weld formed between the second expansion joint and a peripheral shoulder defined by one of the respective steel outer sheaths.
8. The device of claim 6, wherein the socket of the second ball-and-socket joint is formed in a first tubular connector member comprising a refractory inner lining and a steel outer sheath and the first tubular connector member is arranged coaxially within the steel outer sheath of the downstream tubular conduit member.
9. The device of claim 8, wherein a first portion of the refractory insert of the second ball and socket joint is secured to the steel outer sheath of the first tubular connector member and a second portion of the refractory insert of the second ball-and-socket joint is secured to the refractory inner lining of the first tubular connector member.
10. The device of claim 8, wherein a first portion of the refractory annular insert of the second ball-and-socket joint is secured to the steel outer sheath of the first tubular connector member and a second portion of the refractory annular insert of the second ball-and-socket joint is secured to the refractory lining of the first tubular connector member.
11. The device of claim 8, wherein the first tubular connector member further comprises a ring secured inside the steel outer sheath, wherein a first portion of the refractory seal of the second ball-and-socket is secured to the refractory inner lining of the first tubular connector member and a second portion of the refractory seal is secured to the ring of the fist tubular connector member.
12. The device of claim 1, wherein the concave socket portion of the first and second ball-and-socket joints are provided on the respective inlet and outlet ends of the central tubular conduit member and the convex ball portions are provided on the outlet end of the upstream tubular conduit member and on the inlet end of the downstream tubular conduit member, respectively.
13. A process for manufacturing convex ball-parts of ball-and-socket articulations of a device for injecting preheated air into a shaft furnace, consisting of first making the ball-part sheath of refractory steel and providing it with an inner refractory lining, characterized in that the end of a tubular element made of refractory steel is formed until it has the shape of a convex dome with a central opening and a convex spherical surface extending between the central opening and the cylindrical surface of the tubular element, that the sheath thus formed is placed on a support, that a cylindrical form having a diameter slightly inferior to the diameter of said central opening is arranged axially to the inside, and that the refractory material is cast between said cylindrical form and said sheath.
14. A process according to claim 13, characterized in that a plurality of triangular cuttings are formed into the end of the tubular element of refractory steel, the triangular cuttings defining tongues identical to each other all around the tubular element, that all said tongues are bent towards the axis of the tubular element until the cuttings have completely disappeared by joining the tongues to form, by juxtaposing the frontal faces of the tongues, a central opening and a convex spherical surface which extends between the central opening and the cylindrical surface of the tubular element, and that all the tongues are welded to each other.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU87838 | 1990-11-09 | ||
| LU87838A LU87838A1 (en) | 1990-11-09 | 1990-11-09 | DEVICE FOR INJECTING PREHEATED AIR INTO A TANK OVEN AND METHOD FOR MANUFACTURING BALLS CONVEXED WITH SPHERICAL ARTICULATIONS |
| BR919104978A BR9104978A (en) | 1990-11-09 | 1991-11-08 | PRE-HEATED AIR INJECTION DEVICE IN A VESSEL OVEN AND CONVEXED SPHERICAL JOINT LABELING PROCESS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2053935A1 CA2053935A1 (en) | 1992-05-10 |
| CA2053935C true CA2053935C (en) | 2002-12-10 |
Family
ID=25664466
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002053935A Expired - Lifetime CA2053935C (en) | 1990-11-09 | 1991-10-22 | Device for injecting preheated air into a shaft furnace and process for manufacturing ball-and-socket joints |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0484720B1 (en) |
| CN (1) | CN1044006C (en) |
| AT (1) | ATE124462T1 (en) |
| AU (1) | AU637939B2 (en) |
| BR (1) | BR9104978A (en) |
| CA (1) | CA2053935C (en) |
| CZ (1) | CZ284580B6 (en) |
| DE (1) | DE4136649C2 (en) |
| ES (1) | ES2089085T3 (en) |
| LU (1) | LU87838A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU88241A1 (en) * | 1993-03-31 | 1994-10-03 | Wurth Paul Sa | Device for injecting preheated air into a shaft furnace |
| DE102010015842A1 (en) | 2010-03-05 | 2011-09-08 | Z & J Technologies Gmbh | Hot blast nozzle stick for a shaft furnace, in particular blast furnace |
| FR3000133B1 (en) * | 2012-12-26 | 2015-01-16 | Renault Sa | EXHAUST LINE OF A MOTOR VEHICLE HAVING AN IMPROVED BALL |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE632354A (en) * | ||||
| US1405683A (en) * | 1919-07-07 | 1922-02-07 | David T Croxton | Tuyere stock |
| LU63079A1 (en) * | 1971-04-29 | 1971-08-27 | ||
| US3766868A (en) * | 1972-02-22 | 1973-10-23 | Anciens Etablissements P Warth | Tuyere stock for furnaces |
| AU608987B2 (en) * | 1988-07-19 | 1991-04-18 | Paul Wurth S.A. | Device for injecting preheated air in a shaft furnace |
-
1990
- 1990-11-09 LU LU87838A patent/LU87838A1/en unknown
-
1991
- 1991-10-18 AU AU85929/91A patent/AU637939B2/en not_active Ceased
- 1991-10-19 AT AT91117866T patent/ATE124462T1/en not_active IP Right Cessation
- 1991-10-19 EP EP91117866A patent/EP0484720B1/en not_active Expired - Lifetime
- 1991-10-19 ES ES91117866T patent/ES2089085T3/en not_active Expired - Lifetime
- 1991-10-22 CA CA002053935A patent/CA2053935C/en not_active Expired - Lifetime
- 1991-11-07 DE DE4136649A patent/DE4136649C2/en not_active Expired - Lifetime
- 1991-11-08 CZ CS913401A patent/CZ284580B6/en not_active IP Right Cessation
- 1991-11-08 BR BR919104978A patent/BR9104978A/en not_active IP Right Cessation
- 1991-11-08 CN CN91110568.9A patent/CN1044006C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| AU8592991A (en) | 1992-05-14 |
| EP0484720A1 (en) | 1992-05-13 |
| ES2089085T3 (en) | 1996-10-01 |
| EP0484720B1 (en) | 1995-06-28 |
| CN1044006C (en) | 1999-07-07 |
| CZ284580B6 (en) | 1999-01-13 |
| DE4136649C2 (en) | 2000-02-24 |
| DE4136649A1 (en) | 1992-05-14 |
| BR9104978A (en) | 1992-06-23 |
| CS340191A3 (en) | 1992-05-13 |
| AU637939B2 (en) | 1993-06-10 |
| CA2053935A1 (en) | 1992-05-10 |
| CN1061655A (en) | 1992-06-03 |
| ATE124462T1 (en) | 1995-07-15 |
| LU87838A1 (en) | 1992-08-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121202 |