GB2127531A - Cooling system for blast furnaces - Google Patents

Abstract

The invention relates to cooling systems for the steel jacket (5) of a blast furnace provided with cooling boxes. The system consists of cooling pockets arranged peripherally on the outside of the jacket (5) the pockets comprising divergent longitudinal walls (2) attached to the steel jacket and having strips (7) which project beyond the upper edge of the wall (2) to guide cooling water toward the jacket (5). To accommodate thermal stresses, the longitudinal walls (2) of the cooling pocket (1) are provided with corrugations (6) extending from the upper edge (3) to the line of contact (4) with the jacket (5). The corrugations (6) are traversed by the strip (7) and provide passage for cooling water from the pockets (1) between the lower edge of the strip and the furnace jacket. <IMAGE>

Description

SPECIFICATION Cooling system for blast furnaces The invention relates to a cooling system for blast furnaces which are provided with cooling boxes. Known such systems have metallic cooling pockets arranged externally on the furnace jacket which are provided with normally pre-stressed elastic strips to guide cooling water toward the jacket, and which project beyond the upper edge of the respective wall of the cooling pocket.

A cooling system of the above known type is described in German Patent No: 25 36 322.

Owing to the rigid construction of the cooling pockets provided therein, varying thermal expansions between furnace steel jacket and cooling pockets frequently lead to faults on the cooling pockets. Furthermore, the manufacture of the strips, including in their structural design attachment elements, requires comparatively high production costs.

The present invention seeks to further develop cooling systems of the type described above in such a manner that thermal stresses are compensated on the cooling pockets so that the guidance of cooling water, is retained, while simultaneously achieving a simplification in the manufacture of the strip.

To the above ends, a cooling system according to the invention comprises cooling pockets extending peripherally on an external surface of a jacket for the furnace, each pocket being defined by a divergent longitudinal wall having spaced corrugations and joined to the jacket at its lower edge, and a strip mounted against the wall which traverses the corrugations and extends beyond the upper edge of the wall to direct cooling water towards the jacket, the corrugations providing passage for such cooling water from the pocket between the lower edge of the strip and the jacket. The strip is normally of pre-stressed elastic material, and the longitudinal wall and jacket of steel. The strip is preferably disposed on the inside surface of the longitudinal wall; i.e., between the wall and the jacket. The strip may take the form of a normally planar sheet or length thereof.

The cooling pockets in systems according to the invention can take up stresses as a result of the differing thermal expansions of cooling pockets and furnace steel jacket, whilst maintaining their full operational efficiency. In addition, because the form of the elastic strip required for the guidance of water on the cooling pocket is simplified, manufacturing costs are reduced.

Two embodiments of the invention will now be described by way of example and with reference to the accompanying diagrammatic drawings wherein: Figure 1 shows an elevation of part of a furnace jacket, showing a cooling system with cooling boxes and cooling pockets; Figure 2 shows a transverse section through the jacket of Figure 1; Figure 3 shows an enlarged cross-section through a cooling pocket embodying the invention, in the vicinity of one of its side walls, along the line B-B of Figure 1; Figure 4 shows a similar cross-section to that of Figure 3, but illustrating an alternative embodiment; and Figure 5 shows a development of the longitudinal wall of a cooling pocket, in which the profile line B'-B' corresponds to the profile line B-B in Figure 1.

In Figures 1 and 2, a furnace steel jacket in the bosh and in the lower shaft area is represented diagrammatically. Whilst the cooling of the brick lining of the furnace takes place through the cooling boxes (9), the steel jacket of the furnace is cooled by sprinkling with water. In order to achieve a uniform cooling, in particular in the region beneath the cooling boxes, the descending cooling water is collected by the cooling pockets (1) arranged staggered one beneath the other and is passed on.

A cooling pocket embodying the present invention is shown in Figure 3, connected with the steel jacket of the furnace and having side walls 10, a longitudinal wall 2 and a mounted elastic strip 7. The sides walls 10 are connected with the steel jacket 5 of the furnace and the wall 2 by welding. The wall 2 has several inwardly directed convexities or corrugation 6 with semicircular cross-sections. As can be seen from the development of the wall 2 in Figure 5, the corrugations 6 run substantially perpendicular to the longitudinal extent of the wall 2. In a particular embodiment, the corrugations 6 have a depth of approximately 12 mm and are spaced from each other by approximately 100 mm. In the region of the line of contact 4 of the wall 2 with the steel jacket 5 of the furnace, the wall 2 is welded onto the steel jacket.In the region of the corrugations 6 in each case the wall 2 is only adapted so as to fit against the steel jacket 5 of the furnace; no connection exists as such. By this means, differing thermal expansions between the steel jacket 5 of the furnace and the wall 2 are accommodated by the corrugations 6 functioning as a compensator and uncontrolled faults in the wall 2 are avoided, without substantially reducing the cross-sectional area of the corrugations 6. The corrugations 6 are covered externally by the elastic strip 7 lying flat in the remaining region of the wall 2 up to an opening in the lower region of the corrugations, but spaced from the junction between the wall 2 and the jacket 5. The passage, open above and below, thus formed by each corrugation 6 represents a suitabie guiding channel for the controlled flow of cooling water.

Impurities in the cooling water partially settle on the base of the cooling pockets or are flushed out through the openings of the corrugations 6, without clogging them. The elastic strip 7 is mounted onto the wall 2 in a known manner by means of screwed-on clips 11. In addition, again in a known manner, the fastening of the strip 7 to achieve the tightest possible abutment against the wall 2 takes place under pre-stressing by means of clamping bolts externally on the side walls 10.

In the embodiment of Figure 4 the elastic strip 7 is constructed such that it extends up to the steel jacket 5 of the furnace. To ensure the outflow of cooling water, recesses 8 are provided aligned with the corrugations 6 in the lower region of the strip 7 where it rests against the jacket 5.

The invention permits a controlled outflow of cooling water to be achieved, which in turn ensures an uniform cooling when differing thermal expansions occur between the steel jacket of the furnace and the cooling pockets. The form of elastic strip required to guide the water is substantially simplified compared with the previously known form and is therefore economic to produce. Replacement, if required, is also facilitated.

Claims (9)

Claims

1. A cooling system for blast furnaces provided with cooling boxes, which system comprises cooling pockets extending peripherally on an external surface of a jacket for the furnace, each pocket being defined by a divergent longitudinal wall having spaced corrugations and joined to the jacket at its lower edge, and a strip mounted against the wall which traverses the corrugations and extends beyond the upper edge of the wall to direct cooling water towards the jacket, the corrugations providing passage for such cooling water from the pocket between the lower edge of the strip and the jacket.

2. A cooling system according to Claim 1 wherein the strip is tightly mounted against the longitudinal wall to direct said water between the wall and the jacket.

3. A cooling system according to Claim 1 or Claim 2 wherein the longitudinal wall is joined to the jacket along uncorrugated lengths of its lower edge, the corrugated portions being adapted to fit against the jacket.

4. A cooling system according to any preceding Claim wherein the corrugations in the longitudinal wall have a semi-circular cross-section.

5. A cooling system according to any preceding Claim wherein the strip is mounted on the side of the longitudinal wall remote from the jacket.

6. A cooling system according to any preceding Claim wherein the lower edge of the strip is spaced from the junction between the lower edge of the longitudinal wall and the jacket.

7. A cooling system according to any of Claims 1 to 5 wherein the lower marginal edge portion of the strip extends over the junction between the lower edge of the longitudinal wall and the jacket, and rests against the jacket therebelow, the strip being formed with recesses to permit said passage of water from the pocket.

8. A cooling system according to Claim 7 wherein the recesses take the form of grooves aligned with the corrugations.

9. A cooling system according to any preceding Claim including side walls at the end of each pocket extending between the longitudinal wall and the jacket.

1 0. Cooling systems for blast furnaces substantially as described herein withbreference to Figures 3 to 5 of the accompanying drawings.