GB2031565A

GB2031565A - Cooling electric-arc furnaces

Info

Publication number: GB2031565A
Application number: GB7921792A
Authority: GB
Original assignee: BBC BROWN BOVERI and CIE; BBC Brown Boveri AG Switzerland
Current assignee: BBC BROWN BOVERI and CIE; BBC Brown Boveri AG Switzerland
Priority date: 1978-06-27
Filing date: 1979-06-22
Publication date: 1980-04-23
Also published as: DE2829453A1; IT7923759A0; JPS556199A; BR7903997A; FR2429985A1; IT1121871B; DE7820149U1

Abstract

A vessel of an electric-arc furnace comprises in its upper portion (2) a cooling box (2') constructed in the form of a supporting structure. The cooling box (2') may be constructed in the form of an annular container with an inlet (8) and an outlet (9) for the cooling water. With the vessel according to the invention, the effect is achieved that the supporting function of the upper portion (2) of the vessel and the cooling function of the cooling box (2') are united in one structure. Preferably the interior of the cooling box (2') is provided with helically disposed water conducting plates (7). <IMAGE>

Description

SPECIFICATION Vessel of an electric-arc furnace The invention relates to a vessel of an electric-arc furnace having a brick-lined hearth, a brick-lined slag zone and a water-cooled upper portion of the vessel.

The continuous water cooling of highly stressed parts of the vessel of electric-arc furnaces has already been used for many years. It is a question of the upper edge of the vessel, of the slag door, of the slag-door frame generally composed of a plurality of cooling boxes and, in the case of a divided vessel, of the two flange portions of the vessel joint. The cooling of the upper edge of the vessel and the flanges of the divided vessel is intended primarily to increase the stability of shape, that is to say to avoid changes in shape of these parts as a result of deformation and distortion caused thermally.

The purpose of the cooling of the slag door and its frame is to increase the stability of shape and to reduce the wear as a result of heat radiation of the melt and the arc, wear as result of splashes of slag and melt. Not only the wear of the steel surface is reduced but also the wear of any refractory material covering the steel surface which may be present.

The performance of the present-day high-power electric-arc furnace is limited by the increasing wear of the ceramic lining of the furnace vessel and the furnace cover.

In the prospectus "Korf-Fuchs-Systemtechnik, Stahlerzeugung; WasserkUhlsysteme fUr Lichtboge nöfen" of Messrs. Gerhard Fuchs KG, Grossapparatebau, Willstdtt-Legelshurt, undated, two examples of cooling devices are described and illustrated. The upper portion of the vessel is cooled by internal or external cooling boxes which are suspended on a frame structure. The cooling box consists of a plurality of parts so that the distribution of the cooling water is expensive. The connection of the cooling box to the frame structure is comparatively complicated and there is the risk of leakages of cooling water at the numerous connecting points.

in accordance with this invention, there is provided a vessel of an electric-arc furnace having a brick-lined hearth, a brick-lined slag zone and a water-cooled upper-portion of the vessel, in which the upper portion of the vessel is formed by at least one cooling box constructed in the form of a supporting structure.

Embodiments to be described herein thus provide vessels which do not have the disadvantages discussed above and which have a very simple construction with which the risk of leakages is kept as low as possible and with which nevertheless a satisfactory effectiveness of the cooling is assured.

With the vessels in accordance with the invention, the effect is achieved that the supporting function of the upper portion of the vessel and the cooling function of the cooling box are united in one struture. In this manner the whole construction is simplified, the production costs are reduced and the risk of leakages is reduced by reducing the number of connecting points.

Advantageously, the cooling box may be constructed in the form of an annular container formed by a cylindrical inner wall forming a wall of the vessel and a cylindrical outer wall, and is provided with at least one inlet (8) and at least one outlet (9) for cooling water. Thus, a simple construction is achieved wherein only one inlet and one outlet for the cooling water is necessary. A large proportion of the furnace vessel is provided directly with an intensive water cooling so that the stability of the upper portion of the vessel is considerably better assured than in the former apparatus.

The interior of the cooling box may be provided with water-conducting plates, to ensure an advantageous circulation of the cooling water in the cooling box. The cooling water may be guided helically by means of the water-conducting plates.

In one embodiment, the upper portion of the vessel is divided from the lower portion of the vessel by a joint which rises obliquely upwards in the region of a tap spout or at least one slag door )in relation to the horizontal plane in the position of rest of the vessel). The effect is achieved that by raising the tap spout the joint is not flooded by the melt even during tipping so that the sealing of the joint does not have to be so great. At the same time, as large a portion as possible ofthe wearing surface remains at the upper portion of the vessel which can more easily be repaired. The upper portion of the vessel down as far as the joint may be provided with water cooling, so that all the linings can be carried out at only one place, namely at the lower portion of the vessel.In this case, the replacement of the upper portion of the vessel is no longer necessary at the intervals hitherto necessary, as a result of which considerable operating costs are saved.

Embodiments of this invention will now bede- scribed, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a vertical artial section through a vessel wall of an undivided vessel with a cooling box according to the invention; Figure 2 is a circumferential development of the cooling box, and a development of the lining is also visible in the lower part; Figure 3 shows a vertical partial section through the same form of embodiment as illustrated in Figures 1 and 2, but the partial section is taken through the tap spout; Figure 4 is a partial section through another embodiment in which the joint of a divided vessel can clearly be seen between the upper portion of the vessel and the lower portion of the vessel; and Figure 5is a vertical partial section through another embodiment of the invention with a higher lining According to Figure 1, a lower portion 1 of a vessel is connected to an upper portion 2. A considerable portion of the upper portion 2 of the vessel is formed by a cooling box 2' which cmprises an inner wall 3 forming a wall of the vessel, and a cylindrical outer wall 4. The cooling box 2' which comprises an inner wall 3 forming a wall of the vessel, and a cylindrical outer wall 4. The cooling box 2' is closed by an upper marginal plate 5 and is supported at the bottom on a supporting plate 6. Disposed in the interiorofthe cooling box 2' are water conducting plates 7, the helical course of which can be seen better in Figure 2.An inlet 8 and an outlet 9 ensures the supply and removal of the cooling water, the inlet 8 being seen twice in the development of Figure 3. Pieces of iron 10 are secured, for example welded, to the inner wall of the vessel 3. They strengthen the cylindrical inner wall 3 of the vessel and also serve as supporting means for a thin ceramic layer 11 which is sprayed onto the inner wall of the vessel. In the lower portion 1 of the vessel there is the lining 12 of massive dimensions, which is disposed in a container wall 13.

A melt 14 is illustrated in the lining 12. In Figures 2 to 5, the same parts are designated by the same reference numerals. In Figure 2 a tap spout 15 can clearly be seen in the lining 12. In Figure 2 the directions of flow of the cooling water are indicated by arrows. The top spout 15 can clearly be seen in Figure 3. It can likewise be seen clearly that in this example, the lining 12 is taken above the tap spout 15.

According to the embodiment of Figure 4, two flange-like supporting plates 16 are constructed and are held together with a securing device 17, for example comprising bolts and keys. Between these supporting plates 16 a joint 18 is illustrated but is drawn thick for the sake of clarity. The further example shown in Figure 5 has a higher lining 12 and the cooling box 2' is supported on the lining 12 through the supporting plate 6.

Claims

1. Avessel of an electric-are furnace having a brick-lined hearth, a brick-lined slag zone and a water-cooled upper-portion of the vessel, in which the upper portion of the vessel is formed by at least one cooling box constructed in theform of a supporting structure.

2. A vessel as claimed in Claim 1, in which the cooling box is constructed in the form of an annular container formed by a cylindrical inner wall forming a wall of the vessel and a cylindrical outer wall, and is provided with at least one inlet (8) and at least one outlet (9) for cooling water.

3. Avessel as claimed in Claim 1 or 2, in which the interior of the cooling box is provided with water-conducting plates.

4. A vessel as claimed in Claim 3, in which the water-conducting plates are disposed helically.

5. Avessel as claimed in Claim 1, in which the upper portion of the vessel is divided from the lower portion of the vessel by a joint which rises obliquely upwards in the region of a tap spout or at least one slag door (in relation to the horizontal plane in the position of rest of the vessel).

6. Avessel as claimed in Claim 5, in which the upper portion of the vessel down as far as the joint is provided with water-cooling.

7. Avessel of an eiectric-arc furnace substantially as herein described with reference to Figures 1 to 3,4 or 5 of the accompanying drawings.