GB2096290A

GB2096290A - Device for introducing gases into metallurgical vessels

Info

Publication number: GB2096290A
Application number: GB8207577A
Authority: GB
Original assignee: Didier Werke AG
Current assignee: Didier Werke AG
Priority date: 1981-03-17
Filing date: 1982-03-16
Publication date: 1982-10-13
Also published as: BR8201312A; ES8302788A1; ES510439A0; BE892511A; JPS57161038A; FR2502177A1; DE3110204A1

Abstract

A device for introducing gases into metallurgical containers comprises a nozzle brick 1 accommodating a gas-permeable brick 2 through which gas may be introduced via a gas connection rod 6 and a tortuous passage 5 defined by a copper tube moulded into the nozzle brick. If the gas-permeable brick should be eroded away the melt enters the tortuous passage 5 and freezes there thus ensuring that the melt can not flow out of the metallurgical container. <IMAGE>

Description

SPECIFICATION Device for introducing gases into metallurgical vessels The invention relates to a device for introducing gases into metallurgical vessels of the type including a refractory gas-permeable brick which may be arranged directly or indirectly in the refractory casing of the vessel and an external gas connection communicating with the gaspermeable brick.

In such devices, which are disclosed, for instance, in U.S. Patent No. 2811346 and French Patent No. 906 327, the connecting passage from the gas connection to the gas-permeable brick takes the shortest possible path, i.e. the brick is in direct communication with the surroundings outside the metallurgical vessel via the gas supply passage. This has the disadvantage that when the gas-permeable brick is destroyed the melt can flow out of the vessel unimpeded and considerably endanger or destroy the surroundings of the vessel. Such happenings are extremely rare but cannot be excluded since the gas-permeable bricks are subjected to substantial stresses, particularly with steel melts.

For instance, as a consequence of the infiltration of steel melts into the open brick pores and the effect of thermal shock, cracks can occur in the brick which result in brick particles being broken off and scavenged away due to the forces of the turbulence in the melt. This destruction mechanism, which is promoted by both chemical attack and physical erosion, can continue until the entire gas-permeable brick has disappeared and finally result in a catastrophic break through of the melt to the exterior.

It is an object of the present invention to improve the gas supply to such gas-permeable bricks in a simple manner for the purpose of avoiding the risk of the melt breaking through.

In accordance with the present invention there is provided a device for introducing gases into metallurgical vessels including a refractory gaspermeable brick, an external gas connection and a tortuous passage connecting the gas connection to the scavenging brick and surrounded by refractory material. Thus when the gas-permeable brick is destroyed, in use, the melt flows under pressure into the tortuous passage surrounded by the refractory material. The melt is stopped there by freezing thereby blocking the passage and thus unexpected melt break-throughs to the gas supply point of the metallurgical vessel and the associated devastating consequences are avoided.

In use, the gas introducing device can be arranged directly in the refractory casing of the metallurgical vessel, but is preferably used in conjunction with a nozzle brick (also referred to as a nest brick) accommodating the gas-permeable brick. In one form of the invention the gaspermeable brick together with the tortuous passage and the gas connection are moulded in a refractory nozzle brick. This embodiment enables the removal and replacement of the nozzle brick as a single gas introduction or scavenging unit (gas scavenging set) from the inner side of the vessel.

Alternatively an exchangeability of individual parts of the device from the exterior of the vessel can be desirable. Thus in a further embodiment the gas-permeable brick is arranged within a refractory nozzle brick and the tortuous passage and the gas connection are moulded in a refractory body arranged in front of the nozzle brick.

The tortuous passage is preferably mounted in the nozzle brick or in the separate refractory body and is preferably defined by a tube of a good thermal conducting metal, preferably copper, and in the most preferred form of the invention is of generally spiral shape. Preferably the major proportion of the length of the tortuous passage extends substantially transverse to the shortest line between the gas permeable brick and the gas connection.

Further features and details of the invention will be apparent from the following description of two specific embodiments which is given by way of example only with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a longitudinal section through a first embodiment on line I-I in Figure 2; Figure 2 is a section on line A-B in Figure 1; and Figure 3 is a view similar two Figure 1 of a second embodiment.

The device for introducing gases into metallurgical vessels shown in Figures 1 and 2 includes a refractory nozzle brick 1 as an integral component and constitutes a gas scavenging unit.

It comprises a frusto-conical, gas-permeable refractory scavenging brick 2 which is provided with a shell 3 of metal plate around its peripheral surface and a base edge strip 4, also of metal plate, which ensures that a gap 6 is defined between the base of the scavenging brick 2 and the nozzle brick 1. Beneath the brick 2 is a copper, spiral-shaped tortuous pipe 5, one end of which communicates with the narrow space 6 beneath the scavenging brick 2 whilst the other end has a gas connection 7. The scavenging brick 2 with its shell 3 and base 4, and the tortuous pipe with the connection 7 are moulded into the cubical nozzle brick 1, which comprises, for instance, mouldable refractory concrete.The unit, which may be referred to as a gas scavenging set, can be lifted by means of a transport bracket 8 secured to the metal shell 3 and extending above the upper surface of the scavenging brick 2.

The unit can, for instance, be built into the wear lining of steel melt ladles and serve to treat the steel melt with scavenging or carrier gases. For this purpose the gas is fed into the ladle via the connection 7, the tortuous pipe 5, the space 6 and then flows through the permeable scavenging brick 2. Should the scavenging brick 2 wear out prematurely then the advancing steel melt passes through the brick 2 into the tortuous passage defined by the conduit 5 protected by the refractory material of the perforated brick 1. The conduit is so dimensioned that the melt cools rapidly and freezes and thus itself blocks the only pathway through which it can break out to the exterior.

By contrast to the compact unit described above, the device of Figure 3 comprises three separate components joined together, namely a scavenging brick 10 surrounded with a metal plate 9, a nozzle brick 11 accommodating the scavenging brick and block-like refractory body 12 in which a tortuous passage 13 and gas connection 14 are moulded and which is reinforced around its periphery with a profile plate 1 5 of substantially U-shaped cross-section.

Between the scavenging brick 10 and the body 12 there is a gas collecting space 1 6. The gas scavenging brick 10 surrounded by the metal plate 10 and the refractory body 12 with the tortuous passage 13 and connection 1 4 can, if required, be replaced from the exterior of the metallurgical vessel. The device function in the same manner as that described in connection with Figures 1 and 2 above.

Claims

1. A device for introducing gases into metallurgical vessels including a refractory gaspermeable brick, an external gas connection and a tortuous passage connecting the gas connection to the scavenging brick and surrounded by refractory material.

2. A device as claimed in Claim 1 in which the gas-permeable brick together with the tortuous passage and the gas connection are moulded in a refractory nozzle brick.

3. A device as claimed in Claim 1 in which the gas-permeable brick is arranged within a refractory nozzle brick and in which the tortuous passage and the gas connection are moulded in a refractory body arranged in front of the nozzle brick.

4. A device as claimed in any one of Claims 1 to 3 in which the tortuous passage is defined by a copper tube in spiral form.

5. A device substantially as specifically herein described with reference to Figures 1 and 2 or Figure 3 of the accompanying drawings.

6. A metallurgical vessel having a refractory casing in which a device as claimed in any one of the preceding claims is arranged through which gas can be introduced into the interior of the vessel.