GB2067259A

GB2067259A - Gas lance cleaning device

Info

Publication number: GB2067259A
Application number: GB8001354A
Authority: GB
Original assignee: Mckee Minerals & Metals Ltd Da
Current assignee: Mckee Minerals & Metals Ltd Da
Priority date: 1980-01-15
Filing date: 1980-01-15
Publication date: 1981-07-22
Also published as: GB2067259B

Abstract

Skull removal apparatus for an oxygen steelmaking lance 8, comprising a pair of opposed replaceable scraper blades 17 arranged above the lance entry branch 6 of a converter, and mounted on arms 14 which are pivotally retractable by means of air cylinders 24. The blades have cutaway positions so that they fit either side of the lance and may be mounted on a "floating" support 16 so as to be self-aligning with the lance. <IMAGE>

Description

SPECIFICATION Gas lance cleaning device This invention relates to steel making, and in particular to an oxygen steelmaking or similar process in which a gas, such as oxygen, is introduced into a bath of metal in a converter vessel by means of a lance.

The oxygen lance is water cooled and is lowered into the vessel containing the bath of metal from above, through an entry branch in a fume hood located above the vessel and arranged to collect and cool the hot dirty waste gases generated by the process. The lance is suspended above the bath and oxygen is blown at high pressure from the lance into the metal.

Over a period of time, it becomes difficult to withdraw the lance because a deposit of slag and metal at the lower end of the lance builds up, this deposit being commonly known as "skull". When the skull reaches a certain size the lance must be replaced, and it is necessary to remove the skull before the lance can be used again. Since this is generally done when the skull has cooled, it is often difficult to remove the skull without damaging the lance.

According to the present invention there is provided apparatus for removing the "skull" from an oxygen lance or other lance used in an oxygen steel making or other similar process, comprising scraper means adapted for mounting over a lance entry branch of the converter vessel so as to scrape the hot, plastic skull from the end of the lance as it is removed from the vessel. Preferably, a pair of opposed scrapers are arranged above the lance entry position, so that they may be retracted to enable the lance to be inserted in the vessel, and may then be moved into engagement with the lance.

One embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation view showing the arrangement of the device of the invention on the hook entry branch of a basic oxygen converter; and Figure 2 is an enlarged side elevation view of a skull removal device in accordance with the invention.

Referring to Figure 1, the molten metal which is being treated by the process is contained in a converter 2, upon which is mounted a fume hood 4 having an inclined stack. A vertically extending branch 6 is arranged on the hood directly above the top of the converter, so that an oxygen lance 8 can be lowered vertically into the molten metal through the branch 6. The skull removal device of the invention is positioned above the branch 6, at the position 10 indicated in Figure 1, on supports 12 connected to the hood.

As shown in Figure 2, the device 10 comprises a pair of opposed scraper arms 14 which are pivotally mounted on a fixed support member 16 carried by the legs 12. Each scraper arm carries at its outer end a replaceable scraper 1 7 which is shaped to fit around the corresponding side of the oxygen lance 8.

Each scraper arm 14 is pivotally mounted on a shaft 1 8 journalled in the housing 16, and can be rotated to retract it from engagement with the lance, by means of a crank arm 20 operated by a connecting rod 22 connected to the piston of an air cylinder 24. The retracted position of the left hand scraper arm 14 is shown in dashed lines in Figure 2.

Each air cylinder 24 is connected to a source of compressed air by a flexible line, and is also pivotally mounted, at 26, to the support member 16, so that it can pivot about point 26 as the connecting rod is extended from the cylinder.

In operation, the scraper arms are moved to the retracted position to enable the lance to be inserted into the converter, and the scraper arms will then be moved back to engage with the lance.

When the lance is hauled up vertically to remove it from the converter, the skull will be progressively wiped off by the scraper 17, and will fall back into the converter.

Frequently, the skull becomes impregnated with steel, which may become welded to the lance in small pieces. The scraping action of the scraper 1 7 will not be sufficient to detach these, but the compressed air in the air cylinder is sufficiently resilient to aliow a slight movement of the scraper arms towards the retracted position so as to allow this build up to pass. The energy stored by this further compression of the air pushes the scraper blade back to the working position when the build up has passed.

In order to ensure that the system is not damaged by an excessive!y large build up of steel on the lance, the air pipe to the cylinder may also incorporate a relief valve which will open if the air pressure behind the piston becomes excessive.

Since the lance may become distorted in use, or may not maintain its theoretical position aligned with the vertical axis of the entry branch, the support member 16 may be mounted in such a way as to enable the arms to "float" in any direction in a horizontal plane, to ensure that they are always kept in engagement with the lance in the working position. Alternatively, the support member 16 may be fixed, but the scraper arms may be connected to a subsidiary support member which is mounted for "floating" movement relative to the support member 16.

1. Apparatus for removing the skull from an oxygen lance or other lance used in an oxygen steelmaking or other similar process, comprising scraper means adapted for mounting over a lance entry branch of the fume hood of the converter vessel so as to scrape the skull from the end of the lance as it is removed from the vessel, in use.

2. Apparatus according to claim 1 in which the scraper means includes a pair of opposed scraper blades which are shaped to fit around the lance.

3. Apparatus according to claim 2 in which the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Gas lance cleaning device This invention relates to steel making, and in particular to an oxygen steelmaking or similar process in which a gas, such as oxygen, is introduced into a bath of metal in a converter vessel by means of a lance. The oxygen lance is water cooled and is lowered into the vessel containing the bath of metal from above, through an entry branch in a fume hood located above the vessel and arranged to collect and cool the hot dirty waste gases generated by the process. The lance is suspended above the bath and oxygen is blown at high pressure from the lance into the metal. Over a period of time, it becomes difficult to withdraw the lance because a deposit of slag and metal at the lower end of the lance builds up, this deposit being commonly known as "skull". When the skull reaches a certain size the lance must be replaced, and it is necessary to remove the skull before the lance can be used again. Since this is generally done when the skull has cooled, it is often difficult to remove the skull without damaging the lance. According to the present invention there is provided apparatus for removing the "skull" from an oxygen lance or other lance used in an oxygen steel making or other similar process, comprising scraper means adapted for mounting over a lance entry branch of the converter vessel so as to scrape the hot, plastic skull from the end of the lance as it is removed from the vessel. Preferably, a pair of opposed scrapers are arranged above the lance entry position, so that they may be retracted to enable the lance to be inserted in the vessel, and may then be moved into engagement with the lance. One embodiment of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation view showing the arrangement of the device of the invention on the hook entry branch of a basic oxygen converter; and Figure 2 is an enlarged side elevation view of a skull removal device in accordance with the invention. Referring to Figure 1, the molten metal which is being treated by the process is contained in a converter 2, upon which is mounted a fume hood 4 having an inclined stack. A vertically extending branch 6 is arranged on the hood directly above the top of the converter, so that an oxygen lance 8 can be lowered vertically into the molten metal through the branch 6. The skull removal device of the invention is positioned above the branch 6, at the position 10 indicated in Figure 1, on supports 12 connected to the hood. As shown in Figure 2, the device 10 comprises a pair of opposed scraper arms 14 which are pivotally mounted on a fixed support member 16 carried by the legs 12. Each scraper arm carries at its outer end a replaceable scraper 1 7 which is shaped to fit around the corresponding side of the oxygen lance 8. Each scraper arm 14 is pivotally mounted on a shaft 1 8 journalled in the housing 16, and can be rotated to retract it from engagement with the lance, by means of a crank arm 20 operated by a connecting rod 22 connected to the piston of an air cylinder 24. The retracted position of the left hand scraper arm 14 is shown in dashed lines in Figure 2. Each air cylinder 24 is connected to a source of compressed air by a flexible line, and is also pivotally mounted, at 26, to the support member 16, so that it can pivot about point 26 as the connecting rod is extended from the cylinder. In operation, the scraper arms are moved to the retracted position to enable the lance to be inserted into the converter, and the scraper arms will then be moved back to engage with the lance. When the lance is hauled up vertically to remove it from the converter, the skull will be progressively wiped off by the scraper 17, and will fall back into the converter. Frequently, the skull becomes impregnated with steel, which may become welded to the lance in small pieces. The scraping action of the scraper 1 7 will not be sufficient to detach these, but the compressed air in the air cylinder is sufficiently resilient to aliow a slight movement of the scraper arms towards the retracted position so as to allow this build up to pass. The energy stored by this further compression of the air pushes the scraper blade back to the working position when the build up has passed. In order to ensure that the system is not damaged by an excessive!y large build up of steel on the lance, the air pipe to the cylinder may also incorporate a relief valve which will open if the air pressure behind the piston becomes excessive. Since the lance may become distorted in use, or may not maintain its theoretical position aligned with the vertical axis of the entry branch, the support member 16 may be mounted in such a way as to enable the arms to "float" in any direction in a horizontal plane, to ensure that they are always kept in engagement with the lance in the working position. Alternatively, the support member 16 may be fixed, but the scraper arms may be connected to a subsidiary support member which is mounted for "floating" movement relative to the support member 16. CLAIMS

3. Apparatus according to claim 2 in which the scraper blades are mounted on retractable arms

4. Apparatus as claimed in claim 3 in which each arm is pivotally mounted on a shaft the shafts being arranged parallel to one another on either side of the rance entry branch, and generally at right angles to the direction of entry of the lance.

5. Apparatus as claimed in claim 4 in which each arm is connected to a pneumatic cylinder, whereby it can be pivoted about the shaft to retract it from the lance entry position by actuating the pneumatic cylinder.

6. Apparatus according to any preceding claim in which the scraper means are mounted on a "floating" support member which is arranged so that the scraper blades automatically align themselves with the lance, in use.

7. Apparatus as claimed in claim 1 and substantially as herein described with reference to the accompanying drawings.