GB2492735A

GB2492735A - Tilting converter

Info

Publication number: GB2492735A
Application number: GB1220491.3A
Authority: GB
Inventors: Robert Kapl; Gerald Wimmer; Peter Wimmer
Original assignee: Siemens VAI Metals Technologies GmbH Austria
Current assignee: Primetals Technologies Austria GmbH
Priority date: 2010-06-17
Filing date: 2011-05-16
Publication date: 2013-01-09
Anticipated expiration: 2031-05-16
Also published as: WO2011157498A3; AT509202B1; GB2492735B; PL67490Y1; RU129931U1; PL121591U1; AT13321U1; WO2011157498A2; DE212011100110U1; CN203269971U; GB201220491D0; AT509202A4

Abstract

The invention relates to a tilting converter, comprising a support ring (2) which surrounds the converter vessel (1) at a distance and which has two diametrically opposite trunnions, wherein the converter vessel (1) is attached to the support ring (2) by means of a plurality of connecting elements, and the opposite ends of a connecting element are rigidly connected to the lower face of the support ring (2) as well as to the converter vessel (1). For a more even distribution of the loads in the connecting elements, the connecting element comprises exactly one rib (3) which is shielded with respect to the converter vessel (1) by a protective element (6, 8, 9), the respective opposite ends of which are likewise connected to the converter vessel (1) and the support ring (2), although only one of said ends is rigidly connected to either the support ring (2) or to the converter vessel (1).

Description

Tilting converter

FIELD OF THE INVENTION

The invention relates to a tilting converter having a trunnion ring that surrounds the converter vessel at a spacing and which has two diametrically opposed trunnions, wherein the converter vessel is secured tc the trunnion ring by means of a plurality of connecting elements, and a connecting element is rigidly secured in each case by means of its opposing ends to the underside of the trunnion ring at one end and to the converter vessel at the other end.

Converters are Liltable metallurgical vessels with a suspension system, in which liquid metals and metal alloys are produced and prccessed. These converter vessels are subject to high heat loads during operation, which can result in consfderable thermal expansion and deformation. For this reason, a trunnion ring surrounds the converter vessel at a predetermined spacing.

In the case of the converter sizes that are common today, in addition to the heat load there are high weight loads on the connecting elements, and these loads vary as a function of the tilt position of the converter vessel. For this reason, the connecting elements are to be arranoed such that overloads on individual connecting elements cannot occur in any operating position of the converter vessel. Further, the connecting elements are to be arranged such that they are largely protected from slag slopping out of the mouth of the converter.

DESCRIPTION OF THE PRIOR ART

So that these demands can largely be met, a series of connecting elements, or systems cf connecting elements, that connect the converter vessel to the trunnion ring are already

known from the prior art in various constructions.

In one construction of the connecting elements, the latter are constructed as stacks of lamella-type elements, that is to say they comprise a plurality of mutually spaced lamellae, usually two or three, as disclosed for example in AT 504 664 El. Here, a plurality of lamella elements is provided that are arranged distributed on the periphery of the underside of the trunnion ring and connect the converter vessel to the trunnion ring.

This type of suspension system is already known from EP 1 061 138 A2. The lamella suspension system has the advantage that it is radially yielding.

Usually, the lamellae are constructed as thin rectangular steel panels. Their small thickness makes them very flaxible, producing only relatively small stresses in the larnellae in the event of thermal deformation of the converter vessel. The arrangement of the larnellae in stacks is supposed on the one hand to distribute the load of the converter vessel over a relatively large cross section and on the other to provide security in the event that individual lamellaa fail. The fact that the connection is provided by the lamellae means the system is statically indeterminate, that is to say that the stresses occurring in the individual lamellae depend on the deformation of the overall system comprising the converter vessel, the trunnion ring and the lamella stacks. Numerical analyses of converters constructed hitherto show clearly that the loads are distributed very unevenly between the lamellae in different stacks but also between the lamellae of one stack and indeed within a lamella. This means that local stress peaks occur, which greatly reduce the service life of the lamellae.

The cause of the uneven load distribution has various causes.

First, the arrangement of the lamellae in stacks has the effect that the lamellae closer to the hot converter vessel -that is to say the inner lamellae -heat up significantly more than the outer lamellae, which are shielded by the inner lamellae. As a result, the inner lamellae expand to a greater extent and then bear only part of the converter load, or place an additional load on the outer lamellae.

Secondly, if the position of the laden converter is straight (Q0 position, with the opening of the converter vessel upward) or upside down (laY position, with the openinc of the converter downward) , the trunnion ring is deformed under the load of the converter vessel, in that the trunnion ring flexes downward as the spacing from the trunnion increases. The lamella stacks close to the trunnion thus bear greater loads than those further away from the trunnions.

Finally, during charging and tapping, when the converter is tilted by -i-9Y or -9Q0, the lamella stacks again bear part of the load, although in this case the converter vessel is primarily supported by additional elements, such as limit stops or horizontal links, on the trunnion ring. However, in this case, as a result of the great width of the larnellae, in the region of a few hundred mm, and the associated resistance to shear, the lamellae bear part of the load of the converter vessel. This results in a shear load in the lamellae and very uneven stress distributions, and looal stress peaks in the lamellae and their securing means.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a tilting converter by means of which the loads in the connecting elements are distributed more evenly.

This object is achieved in that the connecting element comprises precisely one lamella, which is shielded from the converter vessel by means of a protective element that is conneoted by means of its opposing ends both to the oonverter vessel and to the trunnion ring, but only one of these ends is rigidly connected either to the trunnion ring or to the converter vessel.

Because there is now only one bearing lamella for each connecting element, afl the iameilae of all the connecting elements are subject to substantially the same conditions in respect of heat dissipation from the converter vessel. For this reason, an uneven distribution of loads between a plurality of lamellae in a connecting element is no longer possible.

The term lamella is understood in general to mean a thin, narrow and leaf-like that is to say planar -element. This means that the lamella is wider by a multiple than it is thick, and on the *other hand it is also longer by a multiple than it is wide. Typical dimensions of a lamelia according to the invention are 5-20 mm thick, 200-600 mm wide and 1000-2000 mm long.

Typically, the lameila is aiigned such that the plane of the lamella extends parallel to a tangential plane of the converter, as is also the case with the lamella stacks according to the prior art. The lamellae extend inclined with respect to the vertical by a few degrees when the opening of the converter vessel is upward.

The rigid securing of the lamella to the converter vessel and to the trunnion ring may be performed by a screw, pin or weld connection.

hs a result of the protective element, which does not itself have any bearing function, the single lamelia is now better protected from the heat from the converter vessel, with the result that the lamella now expands to less of an extent. This has the effect that the service life of the lamella is made longer and the operating reliability of the suspension system is increased.

Because the protective element does not have a bearing function, the other end of the protective element -the end which is not rigidly connected -may be connected to the trunnicn ring or converter vessel with play in the longitudinal direction in order to permit freedom of thermal expansion of the prctective element -in its longitudinal direction.

The other end of the protective element -the end which is not rigidly connected -may be connected to the trunnion ring or converter vessel by means of a catch mechanism, with the result that the protective element can take on the load of the lamella if the latter fails.

In order to ensure optimum shielding of the lamella from heat, it may be provided for the protective element to be thicker than the lamella. For this purpose, the protective element may for example be twice to three times as thick as the lamella.

In order to ensure optimum shielding of the entire lawella from heat, it may be provided for the protective element to be at least as long and wide as the lamella. In this way, the entire lamella is protected from the direct emission of heat from the converter vessel. In this case, the protective element is mounted congruently with the lamella, in front of the latter and hence between it and the converter vessel.

A possible eirbodirnent provides for the protective element to be arranged at least partly parallel to the lamella. If the protective element and the lamella extend parallel to one another approximately in the region in which they are secured, then it is a simple matter to secure them in the same securing means -for example by means of a spacer.

In order to distribute the load more evenly between the lamellae according to the invention that are arranged on the periphery, it may be provided for the connecting elements to be arranged as close as possible to the trunnion or the opening for the trunnion in the trunnion ring. The connecting elements can of course only be arranged next to one another and not above one another. Fcr this reason, they are best arranged directly below the trunnion and other lainellae at as small a spacing as possible therefrom, to left and right thereof. In this case a respective connecting element having a lamella is arranged for example to left and right of a perpendicular axis through the center point of the trunnicn or the opening in the trunnion ring where the latter is suspended, on the underside of the trunnion rinq, with a further connecting element immediately adjoining it to left and right.

If the connecting elements are all arranged close to the trunnicn, additional elements must be provided for supporting the load of the converter vessel in the position in which it is tilted by plus or minus 9Q° (during charging or tapping), namely the above-mentioned horizontal links or limit stops. In this case, in particular the connecting elements that are arranged closer to the trunnion may be constructed to be wider than the adjacent other connecting elements. Thus, the lamellae may be constructed to have different widths in order to even out the load distribution between the lamellae.

In order to minimize the loads on the lamellae from shear forces in the pcsition of the converter vessel tilted by plus or minus 900T the shape of the lamelia may be optimized, for example by numerical methods. The maximum stresses in the lamella are minimized by maximizing the normal rigidity in the principal direction (longitudinal direction) and minimizing the resistance to shear. This may advantageously be achieved by tapering the lamella from its opposing ends toward the center.

It may be provided, whether or not the lamella is tapered in the center, for the lamella to be constructed to be symmetrical both to its longitudinal axis and to its central transverse axis. In the case of a tapered lameila, this means that the contours of the taper are both symmetrical to the longitudinal axis on either longitudinal side of the larnella and also symmetrical to the central transverse axis, that is to say the tapering is the same distance away from both ends of the lamella and is of the same construction. In this case, even in the event of rotation about jgQO in the plane of the lamella, the latter would once again be congruent with itself.

However, the lamella need not be constructed to be symmetrical but may also be constructed such that it has only twofold rotational symmetry with no symmetry in relation to its longitudinal or transverse axis. The lameila may be tapered approximately in its central region to only a web of the same width, which extends from a longitudinal edge of the untapered region to the untapered longitudinal edge at the other end of the laniella.

However, "asymmetrical" lamellae of this kind may be arranged symmetrically in pairs in relation to one another, in particular symmetrically in relation to a perpendicular axis through the opening for the trunnion.

As a result of the separation according to the invention of the functions, in that the lamella only bears the load and the protective element serves as a protection against heat and an emergency securing means, each of the two may be optimized for its function. There are no stresses in the lamella as a result of uneven thermal expansion, as there are within the lamella stack according to the prior art. The larnella, the protective element and the securing means (usually screws) may thus be made lighter and less expensive. Further, this increases the reliability of the converter suspension system against failures and increases its service life.

By arranging the lainellae close to the trunnion, more even distribution of the load between the lamellae is achieved. This reduces the maximum loads in the lamellae. This on the one hand increases the security and the service life of the converter suspension system and on the other allows the larnellae to be constructed to be lighter and less expensive.

By optimizing the larnella shape, the conditions of rigidity -that is to say the resistance to shear and the rigidity in the longitudinal direction of the lamella -are influenced such that the maximum stresses occurring in the].amellae and in the securing means during charging and tapping are significantly reduced. This also increases the service life of the converter suspension system, and the lamellae may be constructed to be lighter and less expensive.

BRIEF DESCRIPTION OF THE DRRWINGS

The invention will be described by way of example with reference to schematic figures.

Fig. 1 shows a detail of a converter with a lamella according to the invention and a protective element arranged parallel, Fig. 2 shows a detail of a converter with a lamella according to the invention and a protective element arranged obliquely thereto, Fig. 3 shows a detail of a converter with a lameila according to the invention and an angled protective element, Fig. 4 shows a converter in side view, Fig. 5 shows a converter in side view with various lamellae according to the invention, and Fig. 6 shows a converter in side view with asymmetrical lameilae according to the invention.

DESCRIPTION CF THE PREFERRED EMBODIMENTS

Fig. 1 illustrates a detail of a longitudinal section through a converter vessel 1 and the trunnion ring 2. 0f the converter vessel 1, the side wall is visible. The trunnion ring 2 has a box-shaped cross section. The lamella 3 is rigidly connected at cne end, by means of a screw connection, to an upper securing bracket 4, which is welded to the underside of the trunnion ring 2, somewhat away from the center of the trunnion ring. The lamella 3 is rigidly connected at its other (lower) end, by means of a screw connection, to a lower securing bracket 5, which is welded to the converter vessel 1. The lamella 3 extends by more than half its length over somewhat more than the lower third of the straight, cylindrical side wall of the converter vessel 1. The lower part of the lamella 3 extends approximately parallel to the iower side wall, which takes the form of a conical outer casing, of the converter vessel 1.

At a spacing from the lamella 3 there is arranged, parallel to the lamella 3, a straight, thin protective element 6, wherein the protective element 6 is of the same length and width as the lamella 3 but has a greater thickness. The protective element 6 is approximately 1.5 times to twice as thick as the lamella 3.

At its upper end, it is rigidly secured to the upper securing bracket 4 by means of the same screw connecticn as the lamella 3. At the lower end, the protective element 6 is secured to slide in the lower securing bracket 5, by means of a catch mechanism 7. If the lamella 3 were to break, the protective element 6 would take up the load previously borne by the lamella 3 as a result of the catch mechanism 7, which more or less represents a thickened portion of the protective element, with the result that the latter cannot slip out of the securing bracket 5.

Fig. 2 illustrates the same detail of the converter vessel 1 and the trunnion ring 2 as Fig. 1, but the lamella 3 is displaced outward, further away from the converter vessel 1, albeit arranged with the same inclination in relation to the -10 -converter vessel 1 as in Fig. 1. Accordingly, the upper securing bracket 4 is arranged close to the outer edge of the trunnicn ring 2 and the lower securing bracket 5 is constructed to be longer. The straight or planar protective element 8 is in this case constructed to be thicker than that in Fig. 1 (being about twice to three times as thick as the lamella 3) and is welded to the trunnion ring 2, approximately close to the center of the latter. At its lower end, the protective element 8 is once again secured to slide in the lower securing bracket by means of a catch mechanism 7.

In Fig. 3, the construction of the securing scans for the landis 3 is the same as in Fig. 1, but in Fig. 3 an angled protective element 9 is provided. The two limbs of the protective element 9 are constructed such that the upper limb extends parallel to the cylindrical side wail of the converter vessel 1 and the lower limb extends approximately parallel to the lower side wall, which takes the form of a conical outer casing, of the converter vessel 1. The upper end of the protective element 9 is welded very close to the inner end of the underside of the trunnion ring 2. The lower end of the protective element 9 is held in the lower securing bracket 5 by means of a catch mechanism 7, as in the embodiments in Figs. 1 and 2.

The lamellae according to the invention are made from very high-quality, high-strength and heat-resistant steel. The protective elements may be made from the same material or from a less expensive material, which requires a corresponding increase in thickness if the latter is used.

Fig. 4 illustrates the side view of a converter according to the invention. The opening 10 for the trunnion can be seen in the trunnion ring 2 of the converter vessel 1. To left and right of a perpendicular axis through the center point of the opening 10 there is arranged, on the underside of the trunnion

-II -

ring 2, a respective connecting element with a lamella 3, and directly adjoining these to left and right is another. On the opposing side of the converter, where the second trunnion acts, four lamellae 3 are arranged in the same way. Otherwise, no further lamellae 3 are provided. The lamellae 3 are thus not mounted at regular intervals from one another on the trunnion ring 2 or on the converter vessel but only in the region below the trunnion and directly adjoining this. In this case, the two inner lamellae -that is to say those closer to the trunnion are constructed to be wider than the outer ones.

In Fig. 5, too, the converter can be seen in side view, wherein in this case four different lamella shapes according to the invention are illustrated. Each lamella that is illustrated has two different lateral contours, but in the real construction a lamella 3 has only a respective one of the lateral contours, symmetrically on both longitudinal sides.

In the case of the partly elliptical contour 11, an elliptical cutout is provided on the otherwise straight longitudinal side of the lsniella 3, wherein the basic ellipse shape is aligned with its principal axis in the longitudinal direction of the lamella 3 but the principal axis lies outside the originally straight longitudinal side of the lamella.

In the case of the trapezoidal contour 12, the longitudinal side of the lamella 3 has a trapezoidal cutout in the center.

The circular segment contour 13 has a depth of less than one radius of the generating circle, preferably a depth of approximately 301. of the circle radius.

In the case of the semielliptical contour 14, the basic ellipse shape lies with its principal axis as an extension of the straight upper and lower longitudinal contour of the larnella 3.

-12 -Fig. 6 illustrates an embodiment of the invention having asymmetrical lamellae 15. An asymmetrical lamella 15 has a taper in the shape of a web that is approximately half as wide as the untapered lamella and that extends from the one longitudinal edge of the upper end of the iamella to the other longitudinal edge of the lower end. The result is a Z shape that has twofold rotational symmetry but no symmetry in relation to its longitudinal or transverse axis.

The second lamella 15 is arranged with mirror symmetry to the perpendicular axis through the opening 10 for the trunnion. It goes without saying that further lamella pairs comprising asymmetrical lameilae could be arranged to left and right of the two lamellae 15 illustrated, which for their part are similarly arranged symmetrically to one another in relation to the perpendicular axis through the opening 10 for the trunnion.

It is also possible to combine symmetrical lamellae 3 with asymmetrical lamellae 15 in one converter. In the ideal case, a numerical optimization of the lamella shape is carried out -the result usually comprises curves of higher order which can only be made with difficulty. As a simplification, a simplified contour which comes as close as possible to this calculated contour and comprises straight lines, circles and ellipses is then used.

All the laterai contours shown have the common feature that they fcrm a taper in the center of the lamella 3. In each case, the taper increases as seen from the ends of the lamella toward the center. The lamella has its narrowest point in the center.

Approximately a quarter to a third of the length of the lamella (the parts of the lamella inside the securing bracket are not visible in Fig. 5 and Fig. 6) at the upper and lower ends of the lamella has no taper but a straight lateral contour. All the lamellae shown are symmetrical in relation to their -13 -longitudinal axis and transverse axis, through the center point of the lamella.

LIST OF REFERENCE NUMERALS

1 Converter vessel 2 Trunnion ring 3 Lamelia 4 Upper securing bracket Lower securing bracket 6 Straight, thin protective element 7 Catch mechanism S Straight, thick protective element 9 Angled protective element Opening for trunnion 11 Partly elliptical contour 12 Trapezoidal contour 13 Circular segment contour 14 Semielliptical contour Lamella with twofold rotational symmetry