Nozzle assembly having inert gas distributor

• US 5,723,055 A
• Filed: 07/09/1996
• Issued: 03/03/1998
• Est. Priority Date: 10/10/1995
• Status: Expired due to Fees

• Current Assignee: LTV Steel Company, Inc. (LTV Corp.), Vesuvius Crucible Company (Vesuvius Plc)
• Original Assignee: LTV Steel Company, Inc. (LTV Corp.), Vesuvius Crucible Company (Vesuvius Plc)
• Inventors: Janssen, Dominique, Russell, Robert O., Simoes, Jose Antonio Faria
• Primary Examiner(s): KASTLER, SCOTT R
• Application Number:
  US08/677,239
• Time in Patent Office: 602 Days
• Field of Search: 222/602, 222/603, 222/594, 222/597, 266/220, 266/271, 266/236
• US Class Current: 222/603
• CPC Class Codes: B22D 41/58 with gas injecting means
• CPC Class Codes: F27D 3/1518 Tapholes
• CPC Class Codes: F27D 3/16 Introducing a fluid jet or current into the charge porous elements for gas flushing of molten metals B22D1/005

Abstract

A refractory nozzle assembly is provided that effectively prevents the accumulation of alumina deposits around its upper edge where it receives a stopper rod. The nozzle assembly includes a refractory nozzle body having an upper and a lower portion. A bore extends through both the upper and lower portions that has a receiving and a discharge end for receiving and discharging molten metal. An inert gas distributor circumscribes the upper portion of the nozzle body. A sleeve of gas-obstructing refractory material covers the walls of the bore, and defines a seat portion at an upper portion of the bore. A metal sheath substantially surrounds the outer surface of the upper portion. Pressurized inert gas conducted to the upper, gas permeable portion of the nozzle body by the gas-distributing assembly is guided by the gas-obstructing sleeve and the metal sheath so that it flows predominantly through the top edge of the upper portion. The resulting inert gas flow shields the seat portion of the bore from ambient oxygen, thereby preventing the accumulation of alumina deposits on the seat portion that can interfere with the ability of the stopper rod to control the flow of molten metal.

Claims

1. A refractory nozzle assembly for controlling a flow of molten metal, comprising:

a nozzle body having an upper portion and a lower portion formed from a refractory material, and a bore having a receiving end and a discharge end for receiving and discharging molten metal, respectively, said receiving end of said bore being circumscribed by said upper portion of said nozzle body;

a gas distributing means circumscribing said upper portion of said nozzle body for uniformly distributing a pressurized inert gas flow at all points around a top edge of said upper portion, and

means lining said bore for obstructing pressurized inert gas from flowing through the walls of the upper portion of said nozzle body and into the bore such that said inert gas flows substantially exclusively over the top edge of said upper portion, said lining means circumscribing at least said receiving end of said bore and extending to said top edge of said upper portion of the nozzle body.

2. The refractory nozzle assembly defined in claim 1, wherein said upper portion of the nozzle body is formed from a refractory material having porosity of at least 15% so as to be gas conducting, and wherein said lining means is a sleeve of refractory material having a porosity less than 15% so as to be gas obstructing, and said gas distributing means conducts said pressurized gas flow only through said upper portion.

3. The refractory nozzle assembly defined in claim 1, further comprising a layer of impermeable material disposed around the outside of said nozzle assembly for confining said flow of pressurized inert gas through said upper portion of the nozzle body to the top edge of said portion.

4. The refractory nozzle assembly defined in claim 3, wherein said outside layer of impermeable material is formed from a metallic sheath that surrounds the outside surface of said nozzle body.

5. The refractory nozzle assembly defined in claim 1, wherein said gas-distributing means includes a refractory material having a porosity between 20% and 30% forming said upper portion of said nozzle body, and a conduit having a gas outlet end in contact with the refractory material forming said upper portion of said nozzle body, and an inlet end extending through the refractory material forming said lower portion of said nozzle body that is connected to a source of pressurized, inert gas.

6. The refractory nozzle assembly defined in claim 5, wherein said gas-distributing means further includes an annular, gas-conducting groove circumscribing a bottom surface of the refractory material forming said upper portion of said nozzle body.

7. The refractory nozzle assembly defined in claim 5, wherein said gas-distributing means further includes an annular, gas-conducting groove circumscribing a side surface of the refractory material forming said upper portion of said nozzle body.

8. The refractory nozzle assembly defined in claim 1, wherein said gas-distributing means includes an annular conduit circumscribing the upper portion of the nozzle body having a plurality of gas-conducting openings for uniformly distributing inert gas around said upper portion.

9. The refractory nozzle assembly defined in claim 8, wherein said gas-conducting openings face said lower portion of said nozzle body to avoid clogging from surrounding ramming material.

10. The refractory nozzle assembly defined in claim 9, wherein said the outside of said nozzle body is covered by a gas impermeable metallic sheath, and said annular conduit is formed from a double-skinned portion of said sheath.

11. A refractory nozzle assembly for use in combination with a stopper rod for controlling a flow of molten metal, comprising:

a nozzle body having an upper portion, and a lower portion formed from a refractory material, and a bore extending through said refractory materials forming said upper and lower portions having a receiving end and a discharge end for receiving and discharging molten metal, respectively, said receiving end of said bore being circumscribed by said upper portion of said nozzle body and having a seat portion for sealingly engaging a stopper rod;

a gas-distributing means circumscribing said upper portion of said nozzle body for uniformly distributing a pressurized inert gas flow at all points around a top edge of said upper portion of said nozzle body;

a sleeve of refractory material covering the refractory material forming the upper portion of said bore for obstructing pressurized inert gas from flowing through the upper portion of the bore defined by said refractory material and into molten metal flowing through said bore and for providing a seat portion for receiving a stopper rod, said sleeve having a porosity less than the porosity of the refractory material forming said upper portion said sleeve extending to the top edge of said upper portion of said nozzle body, and

a metallic sheath substantially covering the outside of the upper portion of the nozzle body,

wherein said sleeve and said sheath cooperate to direct a flow of inert gas from said gas-distributing means substantially exclusively over the top edge of said upper portion of said nozzle body to shield said seat portion of said bore from exposure to ambient oxygen.

12. The refractory nozzle assembly defined in claim 11, wherein said gas distributing means includes a conduit disposed between said sleeve and said sheath and having an outlet end in communication with said upper portion of said nozzle body.

13. The refractory nozzle assembly defined in claim 12, wherein said gas distributing means further includes an annular groove in said refractory material forming said upper portion for conducting inert gas from said outlet end of said conduit around said upper portion.

14. The refractory nozzle assembly defined in claim 13, wherein said groove is located on a lower wall of said refractory material forming said upper portion.

15. The refractory nozzle assembly defined in claim 13, wherein said groove is located on a sidewall of said refractory material forming said upper portion.

16. The refractory nozzle assembly defined in claim 11, wherein said gas distributing means includes an annular conduit circumscribing the metallic sheath substantially covering said upper portion having a plurality of gas-conducting openings for uniformly distributing a flow of inert gas around said upper portion.

17. The refractory nozzle assembly defined in claim 16, wherein said gas conducting openings face said lower portion of said nozzle body to avoid clogging by ramming material surrounding the nozzle body.

18. The refractory nozzle assembly defined in claim 16, wherein said conduit is an annular metallic pipe affixed to said metallic sheath.

19. The refractory nozzle assembly defined in claim 16, wherein said conduit is an annular, double-skinned portion of said metallic sheath.

20. The refractory nozzle assembly defined in claim 11, wherein said gas distributing means includes a source of pressurized inert gas for generating a flow of inert gas at a rate of 15 liters per minute.

21. The refractory nozzle assembly defined in claim 11, wherein said upper portion of said nozzle body is formed from a refractory material having a porosity of between about 25% and 30% so as to be gas conducting, and wherein said gas distributing means conducts said flow of inert gas through said upper portion.

22. The refractory nozzle assembly defined in claim 21, wherein said lower portion of said nozzle body is formed from a castable alumina refractory material having a porosity of between about 15% and 20%.

23. A refractory nozzle assembly for controlling a flow of molten metal, comprising:

a nozzle body having an upper portion formed from a refractory material having a porosity of at least 15% as to be gas conducting, and a lower portion formed from a refractory material, and a bore extending through said refractory materials forming said upper and lower portions having a receiving end and a discharge end for receiving and discharging molten metal, respectively, said receiving end of said bore being circumscribed by said upper portion of said nozzle body;

a gas-distributing means circumscribing said upper portion of said nozzle body for conducting a flow of pressurized, inert gas through only said upper portion of said nozzle body and uniformly distributing said flow of gas at all points around a top edge of said upper portion;

, and

means lining said bore for obstructing pressurized inert gas from flowing through the walls of the bore defined by said upper portion of said nozzle body and for redirecting said inert gas so that it flows substantially exclusively through the top edge of said upper portion and shields said top edge from exposure to ambient oxygen, said sleeve extending to the top edge of the upper portion of said nozzle body.