EP0236135A2

EP0236135A2 - Vessel support arrangement

Info

Publication number: EP0236135A2
Application number: EP87301895A
Authority: EP
Inventors: Donald Alan Atkinson
Original assignee: Davy Mckee Stockton Ltd
Current assignee: Kvaerner Engineering and Construction UK Ltd
Priority date: 1986-03-05
Filing date: 1987-03-04
Publication date: 1987-09-09
Also published as: JPS62235411A; EP0236135A3; IN169316B; GB8605455D0

Abstract

A support arrangement for a vessel l, such as a basic oxygen converter vessel, comprises a substantially circular flanged trunnion ring 2 within which the vessel is located and having diametrically opposed trunnion pins l5 about which the ring may pivot to tilt the vessel, three brackets secured to the vessel including first and second brackets 3 substantially symmetrically positioned on opposite sides of the vessel and each adjacent a corresponding trunnion pin l5 and a third bracket 4 at a position intermediate the first and second brackets, stops l9 on the ring positioned so as to lie adjacent one to each end of the first and second brackets, and claw members 6 secured to a flange (e.g. l2 or l2ʹ) of the trunnion ring and directly engaging the brackets and the stops.

Description

This invention relates to a support arrangement for a vessel, such as the vessel of a basic oxygen converter.
A basic oxygen converter vessel is conventionally supported in a circular trunnion ring. Various means of connecting the two elements are known, all of which are required to comply with the following:-

1. The support arrangement must be able to hold the vessel securely within the trunnion ring at any angle of rotation about the trunnion pin axis.
2. Since the vessel will be higher in temperature than the ring during the steelmaking sequences, the support arrangement must permit the vessel to dilate with respect to the ring and also to contract when cold, without any hindrance in each case.
3. The support arrangement must transmit the vessel rotation torques properly from the trunnion ring to the shell.

A common arrangement for supporting the vessel within the ring is by means of a series of brackets attached either by welding or bolting to the vessel. These brackets locate against the upper and lower flanges of the trunnion ring. In a typical arrangement there are six or eight brackets above the ring and a corresponding number below the ring. Stops are welded to the lower flange at each end of the lower brackets for location purposes, while claws are secured to the upper flange at each end of the upper brackets for the same purpose. For manufacturing reasons a gap is left between each bracket and its mating claw in which a key or pack is fitted upon assembly at site. Maintenance of these packs has proved to be difficult; on occasions packs have come out of position in service of the vessel and caused maintenance problems. A further disadvantage of this known design of vessel support arrangement is that it is structurally indeterminate as it is not possible to ensure that all brackets are sharing equally the weight of the vessel and its contents. It has accordingly usually been assumed by the designer that the weight is carried by a percentage only of the brackets and the brackets have then been sized for that duty.
The present invention accordingly seeks to avoid the disadvantages associated with provision of packs in the conventional design. It further seeks to provide an improved support arrangement for a vessel, such as a basic oxygen converter vessel, in which the need for packs is obviated. Furthermore it seeks to provide a structurally determinate support arrangement for a vessel, for example a vessel for a basic oxygen converter.
According to the present invention there is provided a support arrangement for a vessel, such as a basic oxygen converter vessel, comprising a substantially circular flanged trunnion ring within which the vessel is located and having diametrically opposed trunnion pins about which the ring may pivot to tilt the vessel, three brackets secured to the vessel including first and second brackets substantially symmetrically positioned on opposite sides of the vessel and each adjacent a corresponding trunnion pin and a third bracket at a position intermediate the first and second brackets, stops on the ring positioned so as to lie adjacent one to each end of the first and second brackets, and claw members secured to a flange of the trunnion ring and directly engaging the brackets and the stops. In this arrangement there need thus be three, and only three, brackets which support the whole weight of the vessel and its contents relative to the ring. In this way there is achieved a stable and structurally determinate support arrangement. Moreover, as the claws interact directly with the brackets and the stops, there are no packs as in the conventional design of support arrangement.
At erection the vessel is positioned in the ring, the three brackets are bolted or otherwise secured to the vessel, the dimensions between the stops and the ends of the brackets are measured, and then the claws are machined to suit prior to fitting the claws.
The trunnion ring may have either an upper flange or a lower flange but preferably has both upper and lower flanges. The brackets may be mounted either above or below the ring; in a preferred arrangement they are mounted below the ring and are secured by means of claws attached to the lower annular flange on the trunnion ring. In this way the brackets are protected by the ring from any slopping from the vessel.
In addition to the stops provided at the ends of the first and second brackets, there may also be stops on the ring at the ends of the third bracket.
In order that the invention may be clearly understood and readily carried into effect a preferred embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, wherein:-

Figure l is a side view of a basic oxygen converter vessel incorporating a support arrangement in accordance with the invention;
Figure 2 is a side view of part of the vessel of Figure l on an enlarged scale, showing one of the brackets and two possible forms of trunnion ring;
Figure 3 is a section on the line X-X of Figure 2; and
Figure 4 is a section on the line Y-Y of Figure 2.

Referring to the drawings, and to Figure l in particular, a basic oxygen converter vessel l is supported in a trunnion ring 2 by means of three brackets, i.e. a first bracket 3, a corresponding second bracket (not shown) on the opposite side of vessel l, and a third bracket 4. Reference numeral 5 indicates the centre line of the trunnion pins, which are not shown in Figure l. Claws 6 serve to locate the corresponding brackets 3, 4 relative to the ring 2. Vessel l is provided with a tap hole 7 in the usual way.
Figure 2 shows the brackets 3, 4 in more detail; for the sake of clarity the claw and bolt have been omitted from the right-hand side of bracket 3 as shown. Each bracket has a vertical leg 8 which is shaped to conform to the outer surface of vessel l and which is secured to the vessel l by means of bolts 9 which pass through both the vessel wall and the vertical leg 8 of the bracket (see also Figure 4). The horizontal leg l0 of each bracket has two thick blocks ll fabricated into each of its ends which contact the lower flange l2 of trunnion ring 2. These blocks ll are connected by a bridging plate l3. The faces of blocks ll which contact ring flange l2 are dressed to ensure good bracket to ring contact.
Figure 2 indicates two possible forms of trunnion ring. As indicated to the right of the line Y-Y the lower flange l2 may be continuous around the trunnion ring 2, as is also the upper flange l4 in this embodiment. Alternatively the upper and lower flanges l2ʹ and l4ʹ may be interrupted in the region of the trunnion l5, as indicated to the left of the line Y-Y in Figure 2; in this case a stiffening plate l5ʹ may be added to span the gap in the upper flange l4ʹ.
Each claw 6 is secured in position by means of bolts l6 which pass through corresponding clearance holes l7 in lower flange l2 and are pre-stressed by means of a hydraulic nut l8 to prevent stress cycling. As shown in the drawings the claws 6 for bracket 3 are each secured by means of a pair of bolts l6, while the claws 6 for bracket 4 are each secured by a single bolt l6; it is, however, equally possible to use a pair of bolts l6 to secure each of the claws 6 for bracket 4 in the same way that the claws 6 for bracket 3 each have a pair of such bolts. Each claw 6 directly engages the corresponding block ll and is backed up by a respective block l9 welded to the lower flange l2; this arrangement ensures that, when the vessel l is laid over on its side for tapping or sampling, the claw bolts l6 are not subjected to appreciable shear loads. If desired, thickening pads (not shown) can be welded to the flange l2, prior to drilling holes l7 through both pad and flange, for the purpose of reinforcing the flange. The face of each block l9 which fits against the corresponding claw 6 is machined flat prior to bring welded to the trunnion ring 2.
At erection the vessel l is positioned within the ring 2 in its correct concentric position. The three brackets are then bolted by means of bolts 9 to the vessel l. If desired bolts 9 can be spotface welded to the vessel l prior to tightening up their associated nuts. Spacers can be inserted on each bolt 9 between vessel l and the corresponding bracket. The dimension between each stop bracket l9 and the corresponding bracket is measured at a number of points, for example at four points, and the respective claw 6 is then machined to suit, allowing for a small clearance (for example, about l mm clearance) in order to allow for dilation of the vessel l during the steelmaking sequences.
With the vessel l in its blowing position, as shown in Figure l, the weight of the vessel and its contents is taken at points A on the first bracket 3 and the corresponding second bracket (not shown) on the opposite side of the vessel l. If the centre of gravity of the vessel should be slightly off centre, then more weight will be taken by one claw and proportionately less by the other.
When the vessel l is inverted as for slagging off, the weight of the vessel is taken at points D.
When the vessel l is in its tapping and sampling position, the weight of the vessel is supported on the ends of the first and second brackets at B. However, the centre of gravity of the vessel and its contents does not in this case lie on the line of action of forces B. As a consequence there is a tendency for the vessel l to rotate about B with respect to the trunnion ring 2. This motion is resisted by the third bracket 4 at C, the direction of force C depending on the attitude of the vessel l.
At intermediate angles, the vessel l will be supported by a combination of these forces.
The third bracket 4 is also responsible for transmitting the tilting torque from the trunnion ring 2 to the vessel l. Any tendency for the vessel l to shift within the ring 2 in a direction normal to the axis of the trunnion pins l5 is resisted by the claws 6, whilst any tendency for the vessel l to more along the trunnion pins' axis 5 is restrained by the third bracket 4.
Although the invention has been specifically exemplified in relation to a basic oxygen converter vessel, it will be appreciated by those skilled in the art that the support arrangement of the invention can be applied to other types of furnace vessel.

Claims

1. A support arrangement for a vessel comprising a substantially circular flanged trunnion ring within which the vessel is located and having diametrically opposed trunnion pins about which the ring may pivot to tilt the vessel, three brackets secured to the vessel including first and second brackets substantially symmetrically positioned on opposite sides of the vessel and each adjacent a corresponding trunnion pin and a third bracket at a position intermediate the first and second brackets, stops on the ring positioned so as to lie adjacent one to each end of the first and second brackets, and claw members secured to a flange of the trunnion ring and directly engaging the brackets and the stops.

2. A support arrangement according to claim l, in which the claws are machined to suit the dimensions between the ends of the stops and the ends of the brackets which result after the three brackets are secured to the vessel.

3. A support arrangement according to claim l or claim 2, in which the trunnion ring has both upper and lower flanges.

4. A support arrangement according to any one of claims l to 3, in which the brackets are mounted below the ring.

5. A support arrangement according to claim 4, in which the brackets are secured below the ring by means of claws attached to a lower annular flange on the ring.

6. A support arrangement according to any one of claims l to 5, in which there are further provided stops on the ring at the ends of the third bracket.