US3555661A - Refractory support - Google Patents

Abstract

A METHOD OF SUPPORTING RETRACTORY ELEMENTS ON THE EXTERIOR OF A DEGASSING APPARATUS NOZZLE BY FORMING A RADIALLY EXTENDING SUPPORT AROUND THE EXTERIOR OF THE LOWER PORTION OF THE NOZZLE AND ENCASING THE SUPPORT AND THE LOWER END OF THE NOZZLE IN A REFRACTORY RING. REFRACTORY ELEMENTS HAVING UPPER AND LOWER TRANSVERSE SURFACES WITH PARALLEL SLOTS THEREIN ARE EMPLACED IN COURSES AROUND THE NOZZLE WITH THE SLOTS ORIENTED TO FORM CONTINUOUS ANNULAR GROOVES. RETAINING RINGS ARE PLACED IN THE SLOTS TO KEY THE RESPECTIVE COURSES TO ONE ANOTHER AND HOLD THE REFRACTORIES AGAINST THE TUBULAR NOZZLE.

Description

Jan. 19, 1971 R. A. RAWLINGS 3,555,661

' REFRACTORY SUPPORT Filed July 2, 1968 2 sheets-sheet z INVENTOR ROBERT A. RAWLINGS ATTORNEY United States Patent 3,555,661 REFRACTORY SUPPORT Robert A. Rawlings, Weirton, W. Va., assignor to National Steel Corporation, a corporation of Delaware Filed July 2, 1968, Ser. No. 741,919 Int. Cl. 1323p 19/00, 15/16 US. Cl. 29-431 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to applying and holding refractory elements to large diameter probe type structures used in molten metal processing such as the tubular nozzle used in the vacuum degassing of molten steel.

In the type of vacuum degassing apparatus to which this invention is particularly directed, a vacuum chamber is disposed above a melt for relative movement toward and away from the melt. A snorkel or nozzle extends downwardly from the lower portion of the vacuum chamber so that, upon relative movement toward the melt, the nozzle is immersed in the melt. A portion of the molten metal is drawn into the nozzle under the influence of vacuum for degassification. After degassification of that portion, the nozzle is [withdrawn from the melt, and the degassed molten metal is returned to the melt. This process is repeated until the required degassification of the entire melt has been accomplished.

The 'flow of molten metal over the nozzle has an eroding effect on the nozzle refractory surface which seriously limits useful life of the nozzle refractory covering. With such structures, the nozzle is generally removable from the vessel to facilitate relining.

Refractory linings of the prior art degassing snorkels have generally been fabricated by casting or ramming the refractory liner on a tubular metal framework. Relining of such a structure requires the removal of the old cast liningwhich is more laborious than recasting or ramming a new lining. So this process is expensive and time consuming and required too frequently because of the wear of the moving metal and slug on the rough surface rammed material.

Also refractory coatings of degassing nozzles present particular problems in that the repeated entry of the snorkel into the melt generates buildup of a skull or coating of metal on the exterior of the nozzle. The weight of this skull imposes a load on the exterior refractory lining. In the past, this exterior cover has been limited to castable material since there was no available way for holding refractory brick to the nozzle framework. The present invention provides a method of supporting exteriorcover refractory brick or elements and holding such brick to the framework. Sufficient structural strength is provided to withstand the weight of the skull of metal while providing ease of assembly and replacement of individual refractory elements.

The invention teaches a method for replacing exterior refractory covers for degassing nozzles which overcomes the disadvantages of the prior art by furnishing a refractory and mechanical interconnection therefore which may be quickly and easily dismantled for replacement.

In a preferred embodiment, the invention provides a replaceable exterior refractory cover for nozzles of degassing apparatus including a plurality of refractory elements disposed in courses around the exterior of a tubular nozzle. A slot in each of the refractory elements extending substantially parallel to the periphery of the nozzle across the upper and lower surfaces of the refractory elements defines a continuous groove, which is concentric with the tubular nozzle, in the upper and lower surfaces of each course of elements. Metallic retainer rings, which are concentric with the tubular nozzle, are received in the grooves formed by the slots. The retaining rings key the refractory elements to one another and restrain movement of the elements in a lateral direction, i.e. hold the brick in place covering the exterior surface of the tubular nozzle. At least oneof the retaining rings is connected to the tubular nozzle, for example by welding.

Objects of the invention will become better understood to those skilled in the art from the following detailed description considered with the accompanying drawings. The same numerals are used, where possible, to describe like components in the drawings.

FIG. 1 is a perspective view of a refractory element in accordance with the invention;

FIG. 2 is an elevational view in section of a degassing nozzle lined with the elements of FIG. 1;

FIG. 3 is a perspective view of another refractory element in accordance with the invention; and

FIGS. 4a through 4d illustrate the steps in assembling a refractory cover in accordance with the invention.

Referring to FIG. 1, refractory element 10 comprises a hexahedron having a pair of flat trapazoidal end surfaces 12 and 14, a pair of parallel side surfaces 16 and 18, and a pair of non-parallel side surfaces 20 and 22. End surfaces 12 and 14 include slots 24 and 26 respectively, disposed intermediate and substantially parallel to side surfaces 16 and 18. The element 10 is preferably formed by precasting refractory material such, for example, as basic refractory material known in the art.

In FIG. 2 the nozzle 28 comprises a tubular metal framework 30 having an annular metal flange 32 fixed to the upper end thereof to facilitate attachment to the snorkel to a vacuum chamber (not shown). An annular metal support flange 34 is aifixed to the lower end of the frame 30. This provides support for the external refractory cover.

A refractory ring 36 is formed around the lower end of the frame 30 enclosing the support flange 34 and the lower exterior surface of the nozzle 28. Refractory ring 36 as shown is fabricated from a course of segmental refractory elements, prefabricated and assembled over the support flange 34.

A novel refractory element 38 for assembling refractory ring 36 is shown in FIG. 3. The element 38 is formed with a radially extending slot 40 on its inner surface and a downwardly extending slot 42 on its upper surface. Slot 40 receives support flange 34 and slot 42 receives a retainer ring as described later. I

The interior of the nozzle 28 can be provided with any suitable refractory lining such as a cast or rammed refractory lining 44.

Ring 46a is disposed in the groove formed by the slots 42 after elements 38 are arranged on the flange 34 to form refractory ring 36. Then flange 48 is secured to the tubular nozzle 30. The ring 46a and flange 48 may be continuous and placed on the nozzle 30 prior to assembly of the flange 34 and elements 38 or, if broken, ring 46 and flange 48 are connected to form a continuous ring after disposition around the nozzle v30. After placement, flange 48 can be welded to tubular nozzle 30.

The remainder of the outer refractory lining 50 is comprised of the refractory elements of FIG. 1. The refractory elements are arranged in courses A, B and C and the refractory elements of the lining will be referred to with the suflix a, b and c as appropriate to the course in which they are situated.

As will be seen by reference to the drawings, the first course of outer lining elements comprises refractory elements 10b, is disposed above course A with the slots 26b the upper portion of the first ring 46a. The elements 10a are arranged with their non-parallel side surfaces 22a in identical abutting fashion to thereby form a ring around the frame 30. The upper slots 24a of the elements 10a thereby align to form a groove which circumscribes the frame 30. A second retaining ring 46b is disposed in the groove formed by the slots 24a and extends above the upper surface of course A. Course B, comprising elements 10b, is disposed above court A with the slots 26]) receiving the upper portion of the ring 46b. In a similar fashion to the ring 46b described above, a second ring 46c is disposed in the groove formed by the slots 24]; and extends above the upper surface of course B. In a like manner, elements 100, forming course C, are disposed on top of the elements 10b with the lower slots 26c thereof receiving the upper portion of the ring 460. The groove formed by the slots 240 in the upper surface of the elements 10c, receives a final retaining ring 46d therein. A filling of rammed or cast refractory material 54 can be formed on the upper surface of the course C to include the upper portion of the ring 46d and thereby complete the structure. As was described above for the ring 48a, the rings 48b through 48d can be continuous and disposed around the frame 30 prior to assembly of the flange 34 and the refractory structure or can be discontinuous and connected, e.g. by welding, to form a continuous ring after emplacement.

In the event ring 36 is to be cast or rammed in situ, refractory course 10A can be placed in position on support flange 34 before ring 46a and flange 48 are emplaced and attached to the frame 30. Refractory material is then cast around flange 34. Also, ring 46a and flange 48 can be secured in place and refractory material cast about flanges 34 and 48 and ring 46a after placement of refractory course A.

As can be seen in FIG. 2, the base structure including the flange 34 supports the cover while the rammed material 54 blocks vertical movement of courses A, B and C. The rings 46a through 46d interlock the various courses to preclude lateral movement of the elements 10 and thereby furnish a mechanically integral structure which can be assembled and removed with facility. Preferably, refractory mortar is used between the elements as part of the assembly.

The relative dimensions of the elements may vary in accordance with the particular use to which the invention is to be put. As illustrated, the elements 10a and 10b of courses A and B may be of identical height while the elements .100 of course C may be of less height to accommodate the specific dimensions of the particular snorkel to be lined. It should be obvious that a greater or fewer number of courses may be provided as required within the scope of the invention. The cross-sectional dimensions of the refractories should be such that a relatively snug fit between retainer rings and slots 24, 26 and 42 is provided. The height of a retainer ring should be substantially greater than the depth of an individual slot, preferably on the order of twice but not greater than twice the depth of an individual slot.

Referring now to FIGS. 4a through 4d, the nozzle 28 is illustrated with the rings 4a through 4d disposed concentrically around the frame 30 and flange 34 secured in place at its lower end. In FIG. 4b, the refractory ring 36 has been emplaced on the flange 34 and the first ring 46a is disposed in the groove formed by the slots 42 (FIG. 3) in the upper surface of the ring. At this point ring 46a can be aflixed to the frame 30 by means of welding or the like. In FIG. 40, the first course of elements 10a has been emplaced on the ring 36, and the ring 46b is disposed in the groove formed by the slots 24a in the uppe rsurface of these elements. In FIG. 4d, the courses 10b and have been emplaced and the material 54 has been cast to complete the assembly.

Flange 48 can be placed at other levels or additional flanges can be used with retainer rings to secure more than one retainer ring to the tubular nozzle if desired.

It has been found that in the practice of this invention, an improved lining life has been obtained. For example, an average of about thirty-five, with a maximum of about fifty, heats could be obtained with prior art linings. Linings constructed in accordance with the present invention have demonstrated a life expectancy in excess of ninety heats.

What has been set forth above is intended as exemplary of teachings to enable those skilled in the art to practice the invention. 'It should, therefore, be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.

What is claimed is:

1. A method of supporting a refractory cover comprising independent refractory elements for protecting the exterior surface of elongated tubular nozzle for use in molten metal processing comprising the steps of:

disposing metallic retainer rings in concentric relationship over the tubular nozzle, securing a refractory support to the tubular nozzle, the refractory support extending radially outwardly from the one longitudinal end of the tubular nozzle,

forming a refractory course about the exterior surface of the tubular nozzle which is supported longitudinally by the refractory support, the refractory course being formed from a plurality of refractory elements each having a slotted surface lying in a plane substantially perpendicular to the central longitudinal axis of the tubular nozzle such that surface slots define a continuous groove in the refractory course concentric with the tubular nozzle,

placing a refractory ring in the continuous groove formed by the surface slots of the refractory elements so as to key the refractory element to one another and restrain lateral displacement of the refractory elements with respect to the tubular nozzle, and

similarly placing successive courses of refractory elements and retainer rings about the tubular nozzle to substantially cover the exterior surface of the tubular nozzle.

2. A method of supporting a refractory cover made up of independent refractory elements for protecting the exterior surface of a downwardly depending tubular nozzle for use in molten metal processing comprising the steps of:

disposing metallic retainer rings in concentric relationship over the depending tubular nozzle, securing a refractory support to the tubular nozzle, the refractory support extending radially outwardly from the lower end of the depending tubular nozzle,

forming a refractory course about the exterior surface of the tubular nozzle which is supported by the refractory support, the refractory course being formed from a plurality of refractory elements each having a slotted transverse surface lying in a plane substantially perpendicular to the central longitudinal axis of the tubular nozzle such that transverse surface slots define a continuous groove in the refractory course concentric with the tubular nozzle,

placing a refractory ring in the continuous groove formed by the surface slots of the refractory elements so as to key the refractory elements to one another and restrain lateral displacement of the refractory elements with respect to the tubular nozzle, and

5 similarly placing successive courses of refractory elements and retainer rings about the tubular nozzle to substantially cover the exterior surface of the tubular nozzle. 3. The method of claim 2 including the steps prior to forming refractory courses about the exterior surface of the tubular nozzle of forming a refractory ring enclosing the refractory support secured to the tubular nozzle, the refractory ring being formed from a plurality of refractory ring elements grooved along their interior side surfaces to receive such refractory support and having a slot in their support surfaces for forming a continuous groove concentric with the tubular nozzle, and

placing a retainer ring in the continuous groove formed by slots formed in the support surfaces of the refractory ring elements to key such refractory ring elements to one another and restrain lateral displacement of the refractory ring elements with respect to the tubular nozzle.

4. The method of claim 2 in which the refractory elements in at least one of the refractory courses include slots in their upper and lower transverse surfaces defining continuous grooves at such surfaces and at least one of the retainer rings interconnects adjacent refractory courses.

5. The method of claim 2 in which at least one of the retainer rings is secured to the tubular nozzle.

6. The method of claim 2 in which mortar is placed between adjacent refractory elements.

References Cited UNITED STATES PATENTS 3,229,359 1/1966 Kramer 29-455X 3,287,875 11/1966 Lakin 29-400X 3,340,832 9/1967 Grigsby 29428X THOMAS H. EAGER, Primary Examiner US. Cl. X.R. 29-457, 455

*zgggg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 55, 661 Dated January 1971 Inventor(s) R. A Rawl ings It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Col. 3, line 9, "ments 10b, is disposed above Course A with the slots 26b" should read ments 10a arranged with their lower slots 26a receiving (page 6, line 18 of specification) Signed and sealed this 11th day of May 1971.

(SEAL) Attest:

EDWARD M.FLEICEER,JR. WILLIAM E. SGHUYLER, JR. Attesting Officer Commissioner of Patents

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