Method and apparatus for inert gas blanketing of a reactor or vessel used to process materials at elevated temperatures such as an induction furnace used to remelt metals for casting

• US 5,518,221 A
• Filed: 11/30/1994
• Issued: 05/21/1996
• Est. Priority Date: 11/30/1994
• Status: Expired due to Term

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Green, John L., Lach, David J., Zurecki, Zbigniew, Best, Robert C.
• Primary Examiner(s): KASTLER, SCOTT R
• Application Number:
  US08/346,647
• Time in Patent Office: 538 Days
• Field of Search: 266/44, 266/207, 266/217, 266/158, 266/159, 222/603, 25/553, 25/555, 432/64, 432/10
• US Class Current: 266/44
• CPC Class Codes: C22B 21/064 using inert or reactive gases C22B21/066 and C22B21/068 take precedence
• CPC Class Codes: C22B 9/006 with use of an inert protective material including the use of an inert gas
• CPC Class Codes: F27B 14/04 adapted for treating the charge in vacuum or special atmosphere
• CPC Class Codes: F27B 14/061 Induction furnaces
• CPC Class Codes: F27B 14/12 Covers therefor
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A method and apparatus for blanketing the surface of material, e.g. molten metal contained in an open top vessel, e.g. induction furnace, by establishing a swirling flow of an inert gas having a density greater than air at the top of the vessel. Inert gas exits the swirl flow through an opening in a flow controlling apparatus having an exit opening with a diameter that is smaller than the base diameter of the swirl adjacent the open top vessel.

Claims

1. An apparatus for gas blanketing an open top vessel containing hot liquids, solids or mixtures of liquids and solids comprising in combination;

a generally cylindrical shaped body of a heat resisting material said body having a first end for placement directly on an open top of said vessel and a second or discharge end which is open and generally parallel to said first end;

a central passage in said body extending from said first end to said second end, said central passage having a larger cross-section at said first end than at said second end;

at least one internal passage in said body terminating in an outlet in said central passage, said outlet located proximate to said first end of said body and adapted to induce a swirling flow to a fluid introduced into said internal passage as it exits said outlet; and

means to introduce fluid into said internal passage.

2. An apparatus according to claim 1 wherein said body is a temperature resistant ceramic material.

3. An apparatus according to claim 1 wherein said internal passage communicates with a plurality of outlets spaced equally around said central passage.

4. An apparatus according to claim 1 wherein said internal passage communicates with two outlets disposed opposite to each other in said central passage.

5. An apparatus according to claim 1 wherein said passage in said body has a cross-sectional shape of truncated cone.

6. An apparatus according to claim 1 wherein said body is formed from a first section having a generally cylindrical internal passage having a diameter at least as large as that of said open top of said vessel and a second section in the shape of a ring having a generally cylindrical shaped passage having a diameter smaller than that of said first section.

7. An apparatus according to claim 1 wherein said passage in said body has a cross-sectional shape of a stepped cylinder having a larger diameter portion extending from said first end of said body and a smaller diameter portion extending from said second end of said body.

8. An apparatus according to claim 1 including a moveable cover for use during pouring to direct fluid flow toward a liquid outlet in said vessel when said apparatus and said cover are installed on said vessel.

9. An apparatus according to claim 1 wherein said vessel is an induction heating furnace.

10. An apparatus according to claim 9 wherein a larger diameter portion of a stepped cylinder is formed as an extension of a crucible in said furnace and a smaller diameter portion is in the shape of a ring placed on said extension.

11. An apparatus according to claim 9 wherein said induction heating furnace has a pouring spout and said body includes a notch said notch adapted for placement adjacent said spout in said furnace.

12. An apparatus according to claim 1 wherein said vessel is a molten metal ladle.

16. A method according to claim 11 wherein said inert gas has a density at least 1.38 times that of ambient air.

13. A method of protecting the opening of an open top vessel to minimize ambient atmosphere contact of material contained in said vessel comprising the steps of:

establishing a swirling flow of an inert gas having a density greater than that of the ambient atmosphere proximate to said open top of said vessel, said swirl having an axis of rotation coincidental with a vertical axis of said vessel and an upwardly vertical velocity component, said swirling flow established by gas flow through an orifice in an inner wall of a generally cylindrical device having a first end placed on said open top of said vessel and a second discharge end, said first and second ends having openings, said first end opening having a greater cross-section than said second discharge end opening, said gas exiting said second discharge end opening at a mean average velocity of between 0.01 and 4.0 feet/second; and

allowing said gas to exit said swirling path from said second discharge end opening a specified distance from said open top of said vessel.

14. A method according to claim 13 wherein said swirling gas has a gas swirl number controlled within the range of 1.0 to 1000.

15. A method according to claim 13 wherein said inert gas is argon.

17. A method according to claim 13 where said swirling flow of gas is established during melting of metal in a titling induction furnace.

18. A method according to claim 14 wherein said exit path of said gas is blocked as said furnace is tilted to pour molten metal into a mold.