WO1990005886A1

WO1990005886A1 - A cooling panel

Info

Publication number: WO1990005886A1
Application number: PCT/SE1989/000665
Authority: WO
Inventors: Mikael Brunner; Erica Granberg; Lars Gunnar Johansson
Original assignee: Mefos-Stiftelsen För Metallurgisk Forskning
Priority date: 1988-11-21
Filing date: 1989-11-17
Publication date: 1990-05-31
Also published as: SE8804202L; SE8804202D0

Abstract

A cooling panel which is intended to be positioned at the slag line of a tiltable steel-smelt arc furnace of the kind which is fitted with three electrodes, and in which the three electrodes give rise to three regions which are subjected to extensive wear as a result of the forces generated by mutual repellation of the arcsproduced by the electrodes. The cooling panel is mounted in the slag line at a location within the aforesaid three regions and includes a first part (1) which is provided with cooling fins and which protrudes through the furnace wall and in towards the furnace space, and a second, outer part (2) which projects outwardly from the furnace-wall and which is provided with channels (3) for the passage of panel-cooling water, which thus also cools the aforesaid three regions where wear is extensive. The panel is preferably made of copper and is combined with MgO-C-brick and refractory material of high thermal conductivity.

Description

A COOLING PANEL

The present invention relates to a cooling panel which is intended to be placed at the slag line of a tiltable steel-smelt arc furnace of the kind which has three electrodes. These electrodes give rise to three regions which are subjected to extensive wear as a result of the forces generated by mutual repellation of the arcs generated by the electrodes.

The electrical alternating effect between the arcs generated by the three electrodes of such a furnace produces forces which act to repel the three arcs, one from the other. This phenomenon results in a mixture of hot gases and aggressive super-heated slag which is thrown in the form of a jet against the region of the furnace wall lying nearest a respective electrode. As a result, there is formed in the furnace three regions, so-called hot-spots, which are subjected to extreme wear. In metallurgical arc-furnaces of this kind, about 3 to 8 kg of tamping mass is normally used for each tonne of steel produced. Of this 3 to 8 kg, about 80% of the tamping mass is consumed at the aforesaid hot-spots. Consequently, in order to achieve a lower tamping-mass consumption, it is a primary interest to ensure that the wear on the furnace in the hot-spot regions will be as little as possible.

A conventional metallurgical electric-arc furnace is provided with water-cooled wall panels. For safety reasons, these walls must terminate at a distance of from about 20 to 40 cm above the surface of the steel bath. This distance depends on the type of furnace concerned. In the case of water-cooled panels a given amount of energy, which reaches about 1 kilowatt hour for each tonne of steel produced and each square meter of cooled wall surface, is carried away with the cooling water. Consequently, it is expedient to limit the cooled surface to those regions- here the cooling panel has the greatest effect, i.e. at the hot-spots. Because the furnace-lining is worn very thin at these regions of extensive wear, there is a danger that the steel-melt will break through the the furnace shell at these re- gions. Such occurrences will result in highly expensive production-stoppages and also place personnel in danger.

The object of the present invention is to eliminate the aforesaid drawbacks of known tiltable steel-smelt arc furnaces and to provide a cooling system whcih is based on cooling elements which effect cooling externally of the furnace wall. This system shall be effective to remove heat in sufficient quanties to ensure that pro¬ tective frozen slag-layers will form, without needing to step-up the smelting-energy input to any apprciable extent.

The invention is characterised in that the cooling panel is mounted in the slag line, within the said three regions of the furnace which are subjected to extensive wear as a result of repellation between the three arcs generated by said electrodes. The panel includes a first part which is provided with cooling fins and which protrudes in towards the furnace space, and second, outer part which projects outwardly from the furnace wall and which is provided with channels for the passage of panel-cooling water, which thus also cools the aforesaid three regions where wear is extensive. The inventive cooling panel functions to lower the temperature of the wall surface facing the furnace space to such a radical extent as to cause the slag to freeze and to form an autogenous lining which will protect the said three regions from wear. One important advantage afforded by the inventive cooling panel is that the cooling-water channels lie outside the furnace wall, therewith increasing safety. The inventive cooling panel will also enable the region located beneath the point where conventional panels terminate to be cooled, and even down to the slag line.

The inventive cooling panel will now be described in more detail with reference to the accompanying drawings, in which Figure 1 illustrates an inventive panel in perspective; Figure 2 shows the pane of Figure 1 from above; and Figure 3 is a cross-sectional view of the panel taken on the line III-III in Figure 2.

The illustrated panel is conceived to have been produced from copper and is provided with cooling-water channels. The panel has cooling fins 1 which are intended to be located in the furnace space and which are filled with a refractory mass of good thermal conductivity. The panel has a part 2 which projects out from the wall of the furnace and which has provided therein channels 3 for conducting cooling water through the panel.

That part of the copper cooling panel which protrudes through the furnace wall and faces towards the furnace space is combined with MgO-C-brick and a refractory material of high thermal conductivity.

Claims

CLAIMS 1. A cooling panel which is intended to be positioned at the slag line of a tiltable steel-smelt arc furnace of the kind which is fitted with three electrodes, and in which said three electrodes give rise to three regio¬ ns which are subjected to extensive wear as a result of the forces generated by mutual repellation of the arcs produced by the electrodes, c h a r a c t e r i s e d in that the cooling panel is mounted in the slag line at a location within said three regions and beneath exist¬ ing water-filled furnace-wall panels; in that the panel includes a first part which is provided with cooling fins (1) and which protrudes through the furnace wall and in towards the furnace space, and a second, outer part (2) which projects outwardly from the furnace-wall and which is provided with channels (3) for the passage of panel-cooling water, which thus also cools the afore¬ said three regions where wear is extensive.

A cooling panel according to claim 1, c h a r a c¬ t e r i s e d in that the panel is made of copper and is combined with MgO-C-brick and refractory material of high thermal conductivity.