LU87283A1 - DEVICE FOR INJECTING PREHEATED AIR IN A TANK OVEN - Google Patents

Description

DEVICE ...... INJECTION ...... AIR ...... PREHEAT ..... IN ...... ONE

FOURACUVE

The present invention relates to a device for injecting preheated air into a shaft furnace, consisting of several separate elements consisting of an outer shield and an inner refractory lining and comprising at least one central tubular element connected, on one side, by a first ball joint and a first compensator to a first tube integral with a circular duct for supplying preheated air surrounding the oven and, on the opposite side, by a second ball joint and a second compensator to a second tube which is extended by an elbow and a nozzle, the latter being articulated by a third articulation with a spherical joint with respect to the wall of the furnace and further comprising at least one pair of tie rods connecting, by articulated means, the first tube to the second tube and in which said first articulation is oriented so that its center of co urbure is located on the axis of said first pipe inside thereof.

These devices, more generally known under the name of "wind carrier" are exposed to mobility and leakage problems. Indeed, as a result of the high temperature of the preheated air (temperature of the order of 1,200 ° C. or more) and the high temperature prevailing inside the oven, the wall of the latter, as well as the circular duct and the wind carrier are exposed to thermal expansion and deformation causing significant relative displacements between the circular duct and the wall of the furnace. It is therefore necessary that the wind carrier is able to compensate for these relative displacements while avoiding leaks of gas or preheated air.

To meet these requirements, US Patent No. 3,766,868 provides a wind carrier of the kind described in the preamble. This wind carrier was subsequently perfected by the design of universal joints with spherical joints of the kind described in document DE-C2-2218331. The three articulations of this wind carrier allow the compensation of all relative movements between the circular duct and the wall of the oven. The tightness at the joints is ensured by bellows compensators, while the mechanical stability is ensured by cardanic connections associated at the level of the first and of the second articulation with a spherical joint at the two opposite ends of the tubular element. central.

To reduce the amplitude of the angular movements of the central element and thus relieve the compensators, it is desirable that the distance between the centers of articulation of this element is as large as possible. On the other hand, to reduce the size and cost of the wind carrier, it is desirable to reduce the dimensions.

The object of the present invention is to provide an injection device of the kind described in the preamble which allows a better compromise between these contrary requirements.

To achieve this objective, the device proposed by the present invention is essentially characterized in that the second articulation is oriented in the opposite direction relative to the first articulation and in that its center of curvature is on the axis of the second tubing, inside of it or of the elbow.

By orienting the two articulations of the central element in opposite directions, it is possible to substantially reduce the length of this central element while maintaining the same distance between the centers of its two articulations.

According to a first embodiment, the tie rods are connected to the two tubes by joints, the centers of which are respectively in two diametrical planes of the tubes, each containing the center of curvature of one of said first or second spherical articulation.

According to another embodiment, the end of each of the tie rods is connected to a flange of said first or second tubing by a pair of washers with adjacent spherical sliding surfaces, the center of curvature of which is situated beyond the end of the tie in a diametral plane of the tubing containing the center of curvature of said first or second spherical joint.

The central tubular part advantageously comprises at least one pair of diametric fins acting as a guide and crossed, for this purpose, by the tie rods in order to ensure alignment of the axis of this central part with the centers of the two joints and avoid , thus, arbitrary displacements of this element.

Other particularities and characteristics of the invention will emerge from the detailed description of some advantageous embodiments, presented below, by way of illustration, with reference to the appended drawings in which:

Figure 1 shows a schematic view, in vertical section, of a conventional wind carrier according to US Pat. No. 3,766,868;

Figure 2 shows a similar view of a wind carrier according to the present invention

Figures 3 and 4 show two vertical sections perpendicular to each other of a first embodiment of the central part of the wind carrier according to the present invention.

Figures 5 to 8 show views similar to those of Figures 3 and 4 and illustrating the different displacements of the central tubular element relative to the adjacent tubes;

FIG. 9 illustrates a second embodiment of the central element;

Figure 9a, shows in detail, an enlarged part of Figure 9;

FIG. 10 shows a third embodiment of the central element;

Figure 10a is a sectional view along the section plane a-a of Figure 10;

FIGS. 11 and 12 respectively represent two variants of the embodiment of FIG. 10.

The known wind carrier shown in Figure 1 by the reference 20 connects a main circular pipe 22, arranged around a blast furnace, to the wall 24 thereof. This blower 20 has a rectilinear oblique section consisting of a central tubular element 26 articulated by its upper end on a tube 28 secured to the circular pipe 22 and by its lower end on a tube 30 which is clamped on an elbow 32. This elbow 32 is extended by a nozzle 34, the end of which is articulated on a nozzle 36 fixed in the wall 24 of the furnace. The upper articulation 38 and the lower articulation 40 of the element 26 are articulations with a spherical joint whose centers of curvature are identified by X and Y. Similarly, the articulation between the nozzle 34 and the nozzle 36 is an articulation 42 with a spherical joint whose center of curvature is represented by Z. The three points X, Y and Z therefore constitute a three-point articulation in space which allows sufficient angular displacements of the nozzle 34 and of the central element 26 to compensate for all the relative movements between the circular pipe 22 and the wall 24 of the oven.

Sealing at the joints 38 and 40 is ensured by bellows compensators 44, 46 fixed respectively on the tubular element 26 and the adjacent pipes 28 and 30. Mechanical stability is ensured by cardan joints 48, 50 connecting also the central element 26 to the adjacent pipes 28 and 30. All of the elements of the wind carrier consist of an external metal shield and an internal refractory lining possibly associated with a sealing material at the joints 38, 40 and 42.

The distance between the centers of curvature X and Y of the joints 38 and 40 is represented by 1 in FIG. 1. The amplitudes of the angular displacements of the central element 26 and, consequently, the stresses of the compensators 44 and 46 will be as much smaller as this distance 1 is greater. On the other hand, lengthening the length 1 increases the dimensions of the wind carrier.

According to the present invention, the lower articulation of the central tubular element is turned over so that the two upper and lower ends of this central element become concave. while the corresponding adjacent ends of the tubing of the circular pipe and that of the elbow become convex. This windshield proposed by the present invention is shown in Figure 2 and the elements corresponding to those of Figure 1 bear the similar references of the 100 series. As can be seen from this Figure 2, the centers of curvature X and Y of the spherical joints 138 and 140 are separated by a distance 1 'which, in the example shown, is equal to the distance 1 in FIG. 1. On the other hand, the total length of the central element 126 has been considerably reduced, the difference in length being illustrated by the distance between the axis 0 ′ of the circular pipe of FIG. 2 and the location of the axis O of the blower carrier of FIG. 1, which has also been shown on Figure 2. This shortening of the wind carrier 120 allows, therefore, a lowering of the circular pipe 122 and a bringing it closer to the wall of the oven. The result, of course, is a reduction in size and a reduction in the cost of manufacturing the wind carrier.

It would also be possible to keep the length of the central element 26 of FIG. 1, which would allow an extension of the distance 1 between the centers X and Y of the spherical joints 38 and 40, that is to say a reduction the amplitude of the angular displacements of this element.

Figures 3 and 4 show in more detail the two joints 138 and 140 on either side of the central tubular element 126. The radii of curvature R1 and R2 of the two spherical joints 138 and 140 are preferably equal.

The present invention also proposes the elimination of the cardan joints 48 and 50 of FIG. 1. However, since the compensators 144, 146 are not able to support the weight of the wind carrier, a pair of tie rods has been provided diametrically opposite one another and connecting the upper tube 128 to the lower tube 130. In the embodiment of Figures 3 and 4, these tie rods 152, 154 are simply engaged on pivots 156 integral with the tubes 128 and 130 However, to allow the necessary mobility described with reference to the following figures, the tie rods 152, 154 must be engaged on the pivots 156 with sufficient clearance. To allow this mobility it is also necessary that the axis of the two pivots 156 of the tubing 128 passes through the center of curvature X of the upper articulation 138. Likewise, the lower pivots 156 must be fixed on the tubing 130 so that their axes pass also through the center of curvature Y of the lower joint 140.

Figures 5 to 8 illustrate different possibilities of mobility of the blower. FIG. 5 illustrates, for example, a relative lateral offset, of an amplitude s between the upper tube 128 and the lower tube 130. Such an offset can, for example, be caused by a horizontal displacement of the circular pipe 122 relative to in the oven or a rotation of this pipe with respect to the oven. As shown in FIG. 5, the axes of the pipes 128 and 130 remain parallel to each other while the central element 126 compensates for this offset by positioning itself so that its axis passes through the centers of curvatures X and Y of the two joints 138 and 140. This movement causes, on one side, a compression of the corrugations of the compensators 144 and 146 and a relaxation of the corrugations of these compensators on the opposite side.

Figures 6 and 7 show flexions, respectively in one direction and in the opposite direction of the blower at the central element 126. In each case the axis of the lower tube 130 is inclined at an angle a relative to the axis of the upper tubing 128. This flexion is compensated by the central element 126 which is automatically positioned so that its axis passes through the centers of curvature X and Y of the two joints, that is to say say that its axis forms an angle a / 2 with the axis of the upper tube 128 and an angle a / 2 with the axis of the lower tube 130. The positions of FIGS. 6 and 7 result essentially from a relative vertical movement between the circular pipe 122 and the wall 124 of the oven.

Figure 8 shows a lateral offset between the upper and lower tubes 128 and 130 similar to that of Figure 5, but in a direction perpendicular to the movements of Figure 5, that is to say that the offset of Figure 8 is located in the plane of Figure 2. It should be noted that Figures 5 to 8 show, by way of illustration, elementary movements, but in practice, the movements of the blower are more complex, it is that is, the offsets and inclinations shown in Figures 5 to 8 can occur at the same time.

Figure 9 shows an advantageous embodiment which allows a shortening of the tie rods of the embodiment of Figure 3. In this embodiment of Figure 9, the two pipes 228 and 230 respectively have a circular flange 258 and 260 which are attached to the compensators 244, 246 and which are crossed by tie rods 252, 254.

The connection between the ends of the tie rods 252, 254 and the flanges 258 and 260 is illustrated in detail in FIG. 9A and with reference to the connection between the tie rod 254 and the flange 258, the three other connections being identical to that of the figure. 9a. The flange 258 has a passage opening 262 of the tie rod 258 which is wide enough to allow a certain inclination of the tie rod 254 relative to the flange 258 as a result of the movements illustrated in FIGS. 5 to 8. The tie rods are maintained by nuts 264 screwed onto the ends of the tie rods, outside the flanges 258, 260. Between each nut 264 and the corresponding flange 258 or 260 are two washers 266, 268 whose adjacent surfaces slide one over the other by following the inclination of the tie rod relative to the flange. According to the particularity of this embodiment, the adjacent sliding surfaces of the washers 266, 268 have spherical curvatures whose center of curvature is located beyond the flanges 258, 260 on the axis of the tie rods 252, 254 or on the extension of these axes. The center of curvature of the washers 266, 268 must also be located in a diametral plane of the tube 228 containing the center of curvature X of the spherical joint 238 between this tube 228 and the central element 226. It is it should be noted that the two washers 266 and 268 can be replaced respectively by a seat secured to the flange 258 and a curved surface of the nut 264.

The advantage of the design according to FIGS. 9 and 9a is that one can either bring each of the flanges 258, 260 closer to the central element 226 by a distance R corresponding to the radius of curvature of the washers 266, 268 and reduce by 2R the length of each tie rod 252, 254, or increase the radii of curvature of the two spherical joints 238, 240 and thus lengthen the distance between their center of curvature X and Y.

FIGS. 5 to 8 have shown that the compensation for the various relative movements between the upper and lower tubing are carried out by aligning the axis of the central element with the centers of curvature X and Y of the two spherical joints. It is proposed, in the embodiment of Figure 10, to assist the optimal positioning of this central element 226 to avoid any random movements and unnecessary friction at the joints of the joints. To this end, the central element 226 is provided with two diametrical fins 270 and 272 extending on either side in a central plane and engaged respectively on the two tie rods 252, 254, with the clearance necessary for correct positioning. In embodiment 10, it is also possible to take advantage of the guiding of the central element 226 to provide on the tie rods 252, 254 supports 274, 276 supporting, by means of the fins 270 and 272, the element central 226 and thus remove the influence of the weight of this element on the sliding surfaces of the lower joint 240 and / or to conserve the space available for the joint.

FIG. 11 shows a variant, in which the simple guide of FIG. 10 is replaced by a double guide to ensure permanent parallelism between the axis of the central element 226 and the two tie rods 252 and 254 and thus eliminate the effects of clearance required between the fins 270 and 272 and the tie rods 252, 254 of the embodiment of FIG. 10. For this purpose, the embodiment of FIG. 11 comprises two pairs of diametric fins 278, 280 and 282, 284 which are positioned on the central element 226 symmetrically with respect to its center. In this embodiment, the tie rods 252, 254 also include supports 286, 288 associated with one of the pairs of fins, for example the upper fins 278, 280.

The embodiment of FIG. 12 is similar to that of FIG. 11, with the difference that the central element 226 is not supported directly by the supports 286, 288, but by means of springs 290, 292, which makes it possible to compensate for the dead weight of this central element and thus avoid harmful effects on the joints of the two upper and lower joints 238, 240.

Claims (8)

1. Device for injecting preheated air into a shaft furnace consisting of several separate elements consisting of an outer shield and an inner refractory lining and comprising at least one central tubular element (126) connected, on one side, by a first articulation (138) with a ball joint and a first compensator (144) to a first tube (128) integral with a circular duct (122) for supplying preheated air surrounding the oven and, on the opposite side, by a second articulation (140) with a ball joint and a second compensator (146) to a second tube (130) which is extended by an elbow (132) and a nozzle (134), the latter being articulated by a third joint (142) with ball joint relative to the wall (124) of the oven and further comprising at least one pair of tie rods (152, 154) connecting, by articulated means, the first pipe (128) to the second pipe (130) and in which said first he articulation (138) is oriented so that its center of curvature (X) is on the axis of said first tube (128), inside the latter, characterized in that said second articulation (140) is oriented in the opposite direction with respect to said first joint (138) and in that its center of curvature (Y) is on the axis of said second tube (130) inside the latter or the elbow (132). 2. Device according to claim 1, characterized in that the tie rods (152, 154) are connected to the two pipes (128, 130) by joints, the centers of which are> respectively in two diametrical planes of the pipes (128, 130 ) each containing the center of curvature (X), (Y) of one of said first or second spherical joints (138, 140). 3. Device according to claim 1, characterized in that the end of each of the tie rods (252, 254) is connected to a flange (258, 260) of said first or second pipes (228, 230) by a pair of washers ( 266, 268) with adjacent spherical sliding surfaces, the center of curvature of which is situated beyond the end of the tie rod (252, 254) in a diametrical plane of the tube (228, 230), containing the center of curvature (X), (Y) of said first or second ball joint (238, 240). 4. Device according to any one of claims 1 to 3, characterized in that the central tubular element (226) is connected by a guide device to the tie rods (252, 254). 5. Device according to claim 4, characterized in that the guide device consists of a pair of fins (270, 272) extending diametrically in a median plane of the central element (226). 6. Device according to claim 4, characterized in that the guide device consists of two pairs of fins (278, 280) and (282, 284) extending diametrically from the central element (226) and symmetrically by relation to the median plane thereof. 7. Device according to any one of claims 4 46, characterized in that the tie rods (252, 254) comprise supports (274, 276, 286, 284) for supporting the central element (226). 8. Device according to claim 7, characterized in that said supports (274, 276, 286, 288) support the central element (226) by means of springs (290, 292).