GB2330898A

GB2330898A - Cooling a surface of a metallurgical vessel

Info

Publication number: GB2330898A
Application number: GB9820278A
Authority: GB
Inventors: Bernhard Enkner; Rudolf Gruber; Ernst Fritz
Original assignee: Voest Alpine Industrienlagenbau GmbH
Current assignee: Primetals Technologies Austria GmbH
Priority date: 1997-10-28
Filing date: 1998-09-17
Publication date: 1999-05-05
Also published as: DE19842715A1; GB9820278D0

Abstract

In a process for cooling a surface of a metallurgical vessel (1), spray jets (13) formed of atomized cooling liquid are used. In order to prevent condensed cooling liquid (17) from draining off the metallurgical vessel (1), the condensed cooling liquid (17) is blown upwards by means of a gas fed under pressure.

Description

1 Process for cooling a surface of a metallurgical vessel 2330898 The

invention relates to a process for cooling a surface of a metallurgical vessel, particularly of a converter, by means of spray jets formed by atomized cooling liquid, as well as a metallurgical vessel for implementing the process.

A process of the type described above is known from EP-B 0 393 970, which is applied to a converter. In this process, the shell of the converter is enclosed by a metallic body located at a distance to this shell, with the inside space formed between the shell and the metallic body being open to the atmosphere, In this Inside space, nozzles are provided which spray atomized cooling liquid in flat jets and essentially parallel to the surface of the shell of the converter. According to EP-B 0 393 970, the entire cooling liquid that comes into contact with the surface to be cooled is to evaporate.

In this process, condensate is formed on the metallic body as a result of the metallic body being located at a distance from the hot shell of the converter, with the condensate draining and dripping off along the metallic body. Since a large quantity of cooling liquid is consumed when the shell of a converter is being cooled, a correspondingly large quantity of condensate occurs, which finally drips off the metallic body. The draining coolant-usually cooling water-accumulates on shop floor level in the area below the converter. This, however, endangers converter operation--.,-- rticuiady since liquid--,] fetal and slag may exit while steel is being transferred from the converter to a ladle or while hot metal is being poured into the conve-'er, and such liquid metal and slag will then also hit the shop floor. If cooling liquid, particularly water, is present on the shop floor and meets the liquid steel or slag, respectively, explosions, pafficularly oxyhydragen explosions, will occur, which are extremely dangerous to the operating crew of the converter as W&1 as to the converter itself.

This danger is similarly serious like that involved in a converter breakout, i.e. when the liquid metal causes a hole to form in the refractory lining of the metal shell of the converter.

1 2 The described problems occur to an increased extent when lining bricks (Mgo-C bricks) of increased thermal conductivity are used. Although these bricks considerably extend the lifetime (service life) of the lining, they also cause an increased heat transfer to the vessel shell so that the shell lifet.ime is reduced if cooling is not specially efficient.

The object of the invention is to avoid these disadvantages and difficulties. The technical problem of the invention is to create a process of the type described above as well as a metallurgical vessel where the danger of explosions, particularly of oxyhydrogen explosions, is considerably reduced and the lifetime of a vessel shell considerably extended.

In a process of the type described above, this problem is solved by blowing the condensed cooling liquid that forms on the metallurgical vessel or on an arrangement of the metallurgical vessel by means of a gas fed under presser, preferably by means of compressed air, in upward direction, with the condensed cooling liquid expediently being blown to the hot surface and at least partially evaporafing.

The condensed cooling liquid blown upwards is carried upwards through the spray jets of the newly fed cooling liquid and again hits the surface of the metallurgical vessel to be cooled, where it evaporates. The vapor is exhausted through the secondary exhaust system usually provided at a metallurgical vessel and located above the metallurgical vessel, U is conveyed into the open air through the shnp ventilating system-.

An essential effect of the process according to the invenfien is that according to the invention the surface can be cooled to a very low temperature, e.g. to 1500C. This is not easily possible according to prior art because if there is the demand for evaporation of the entire coolant a considerably higher minimum surface temperature is to be adhered to, otherwisc full evaporation is not possible. In contrast to the process known from EPB 0 393 970, r.-irtial evaporation of t',,a cooling liquid on the.surface to be cooled suffices according to the invention because condensate does not cause any damage.

1 3 According to a preferred embodiment, the condensed cooling liquid is drained and either blown upwards during draining or collected just under the draining point and subsequently blown upwards.

Cooling liquid can be very easily saved, preferably by blowing the condensed cooling liquid into the cooling liquid spray jet.

In order to ensure that the technical problem on which the invention is based is solved in the case of larger surface areas, condensed liquid is preferably blown upwards by means of several gas jets arranged side by side in circumference andlor one above the other in level.

A specially efficient use of cooling liquid is characterized in that cooling liquid not completely evaporated is exhausted and collected at one or several collecting points and the collected cooling liquid is expediently reused for cooling the surface of the metallurgical vessel. In this process, the cooling liquid flow or the cooling liquid flows, respectively, can be controlled as a function of the water volume exhausted or of the optical impression of the residual coolant thrown back to the vessel wall, respectively.

In the case of a steelmaking plant converter enclosed by a trunnion ring, the process according to the invention is implemented by cooling the surface of the steelmaking plant conxjinrter that faces the trunnion ring bi, means of atomized cr-iing liqui.rl and by blowing the cooling liquid fomied on the trunnion ring upwards by means of compressed air into the gap formed betweinn the trunnion ring and the converter surface.

A metallurgical vessel where the process according to the invention is applied, particularly a converter, with a metallic body aligned parallel to its surface and delimiting a through-gap to this surface, with both ends of this through-gap being open to the itmosphere, with nozzles which. .spray cooling 5qued in atomized condition in or into the through-gap, respectively, is characterized in that below or in the lower area of the through-gap gas nozzles are arranged whose gas jets are directed at the through-gap.

4 i i The metallurgical vessel.is preferably designed as a converter for steelmaking, peripherally enclosed by a trunnion ring, with the throughgap being provided between the trunnion ring and the surface of the converter and both the cooling liquid nozzles as well as the gas nozzles being arranged at a small distance below the through-gap.

In the case of large surface areas, the gas nozzles are advantageously arranged side by side in circumference andlor one above the other in level.

An expedient embodiment is characterized in that an exhaust system is provided above or in the upper area of the through-gap.

A preferred embodiment is characterized in that a slag shield protecting the cooling liquid nozzles and the gas nozzles is provided at the trunnion ring, this slag shield facing the surface of the converter off the trunnion ring, partly overlapping the through-gap and its end zone facing the surface of the converter being designed as cooling liquid collecting trough, in which gas nozzles are arranged.

The invention is described in greater detail by means of an embodiment schematically represented in the drawing. Fig. 1 displays a partial section of a side view of a steelmaking plant converter and Fig. 2 a detail 11 of Fig. 1. Figs. 3 and 4 illustrate the converter including representation of the area below the converter.

Converter 1 for producing steel melt 2 is comprised of metallic outer shell 3 and refractory inner lining 4. Converter 1 is peripherally enclosed by trunnien ring 5 in which converter 1 is supported and which serves to tilt converter 1, in which trunnion ring 5 is swvel-mounted on the foundation through trunnions 6, 7 on horizontal axis 8. Both the support of converter 1 on trunnion ring 5 and the swivel-feature of trunnion ring 5 may be implemented;,,i any embodiment.

Below trunnion 5, closed-circuit water and air lines 7, 8 are arranged from which branch lines 10, 11 branch off radially inwards, i.e. towards converter shell 3, at regular circumferential intervals 9 and open into nozzles 12 for atomizing the cooling liquid, normally cooling water.

Cooling liquid jets 13 are directed at through-gap 14 which is arranged between trunnion ring 5 and converter shell 3 and which opens upwards and downwards to the atmosphere, the surface of converter shell 3 being sprayed with cooling liquid owing to the conical formation of cooling liquid jets 13. The vapor formed ascends through through-gap 14, which is open at the top, and is exhausted by means of a secondary exhaust system or is conveyed into the open air through the shop ventilating system.

When the converter is in upright position, nozzles 12 are protected downwards by means of slag shield 15 mounted to trunnion ring 5 and covering nozzles 12 and branch lines 10, 11 as well as closed-circuit lines 7, 8 downwards. As can be seen particularly from Fig. 2, shield 15 extends into the vertical area below through-gap 14 and is provided with cooling liquid collecting trough 16 in the end zone facing converter shell 3. Collecting trough 16 serves to collect condensation water 17 formed on trunnion ring 5, flowing off along surface 18 of trunnion ring 5 that faces converter shell 3 and draining into cooling liquid collecting trough 16. Cooling liquid collecting trough 16 contains gas nozzles 19 through which compressed gas, particularly compressed air, exits upwards. The compressed air carries along the collecting cooling liquid in upward direction so that the condensed cooling liquid that has drained and is draining is conveyed to cooling liquid spray jets 13 of nozzles 12 and thus is again sprayed onto the surface of converter shell 3.

Fig. 3 shows how enndensed liquid fortnine, on trunnion ring 5 of conventional converter 20 is conveyed into area 21 below the converter according to prior art and forms cooling liquid pools 23 on bottom 22. The cooling liquid dripping off is illustrated by lines 24. Tapping of converter 20 may always cause liquid steel 2 or liquid slag to exit taphole 25, with liquid steel 2 or liquid slag coming into contact with the cooling liquid accumulated on the bottom of the area below the converter. This is reliably prevented according to the invention by blowing the condensed cooling liquid upwards again sn, that it evaporates on the conveiter shell, if necessary, or is exhausted by means of the spenn.dary exhaust system or is conveyed into the open air through the shop ventilating system.

6 The invention is not limited to the embodiment represented in the drawing but can be modified in various respects. For example, the process according to the invention can also be used wC converter cone cooling because condensation water may form in this case too. Furthermore, this process can also be applied to metallurgical vessels of any design, such as electric arc furnaces. Moreover, the process according to the invention can be implemented repeatedly along the height of the metallurgical vessel, i.e. in several superposed levels, e.g. in order to cool a specially large surface.

7

Claims

Patent claims:

1. Process for cooling a surface of a metallurgical vessel (1), particularly of a converter (1), by means of spray jets (13) formed of atomized cooling liquid, characterized in that condensed cooling liquid (17) forming on the metallurgical vessel (1) or on an arrangement (5) of the metallurgical vessel (1) is blown upwards by means of a gas fed under pressure, preferably by means of compressed air.

2. Process according to claim 1, characterized in that the condensed cooling liquid (17) is blown onto the hot surface again and at least partially evaporates.

3. Process according to claim 1 or 2, characterized in that the condensed liquid (17) is drained and either blown upwards during draining or collected just under the draining point and subsequently blown upwards.

4. Process as claimed in any or several of claims 1 to 3, characterized in that the condensed cooling liquid (17) is blown into the spray jet (13) of the cooling liquid.

5. Process as claimed in any or several of claims 1 to 4, characterized in that condensed liquid (17) is blown upwards by means of several gas jets arranged side by side in circumference andlor one above the other in level.

6. Process as claimed in any or several of claims 1 to 5, characterized -. ;n that cooling liquid not compietely evaporated is exhausted and collected at one or several collecting points.

7. Process according to claim 6, characterized in that the collected cooling liquid is reused for cooling the surface of the metallurgica,' vessel (1).

8 1 1 1 1 8. Process as claimed in any or several of claims 1 to 7, characterized in that a converter (1) for steelmaking which is enclosed by a trunnion ring (5) is cooled by means of atomized cooling liquid an its surface facing the trunnion ring (5) and that condensed cooling liquid (17) forming on the trunnion ring (5) is blown upwards into the gap (14) formed between the trunnion ring (5) and the surface of the converter (1) by means of compressed air.

9. Metallurgical vessel (1), particularly converter (1), with a metallic body aligned parallel to its surface and limiting a through-gap (14) to the latter, with both ends of the through-gap (14) being open to the atmosphere, with nozzles (12) for spraying cooling liquid in atomized condiflon in or into the through-gap (14), respectively, characterized in that below or in the lower area of the through-gap (14) gas nozzles (19) are arranged whose gas jets are directed at the through-gap (14).

10. Metallurgical vessel (1) according to claim 9, characterized in that the metallurgical vessel (1) is designed as converter (1) for steelmaking, which is peripherally enclosed by a trunnion ring (5), with the throughgap (14) being provided between the trunnion ring (5) and the surface of the converter (1) and with both the cooling liquid nozzles (12) and the gas nozzles (19) being arranged at a small distance below the through-gap (14).

11. Metallurgical vessel (1) according to claim 9 or 10, characterized in that the gas nn77les (19) are arranged side by side in circumference andlor one ahove the other in level.

12. Metallurgical vessel (1) as claimed in any or several of claims 9 to 11, characterized in that an exhaust system is provided above or in the upper area of the through-gap (14).

13. Converter (1) as c!aimed in any or several of claims 10 to 12, chRracterized in that a slag shield (15) protecting the cooling liquid nozzles (12) and the gas nozzles (19) is provided at the trunnion ring (5), this slag shield (5) facing the surface of the converter (1) off the trunnion ring (5), parfly overlapping the through-gap (14) and its end zone facing the surface of the converter (1) being designed as cooling liquid collecting trough (16), in which gas nozzles (19) are arranged.

-1 r

14. A process according to claim 1, substantially as hereinbefore described with reference to the drawings.

15. A converter according to claim 9, substantially as hereinbefore described with reference to, and as shown in, the drawings.