US3365186A - Apparatus for selectively positioning a degassing vessel - Google Patents

Description

Jan.'23, 1968 R. s. BOSETTI ETAL APPARATUS FOR SELECTIVELY POSITIONING A DEGASSING VESSEL 3 Sheets-Sheet 1 Filed Aug. 24, 1964 mveurons BosETTi RICHARD S FREDERICK C. KALMBACH EVISSEN 7 v ERNSTA'M o RUDOLF avosasasnssn F ig.|. BY v ATTORNEYS APPARATUS FOR SELECTIVELY POSITIONING A DEGASSING VESSEL Jan. 23, 1968 R. s. BOSE'QITI ET AL 3 Sheets-sheet 2 Filed Aug. 24, 1964 INVENTORS.

S. BOSETTI REBERICK C; KALMBACH IglCHARD ERNST A. MEVISSEN RUDOLF E. VOGELSBERGER ATTORNEYS 1968 R. s. BOQSETTI ETAL. 3,36 I

APPARATUS FOR SELECTIVELY POSITIONING A DEGASSING VESSEL Filed Aug. 24, 1964 3 Sheets- Sheet 3 Li i 7 Ll T I l I I i l I I I4 31 32 zvg w I 24 I L' Li I I [N r Fig.7 L i i W @U'HEP C5 F|g.6. A

39 L mveurons.

RICHARD S. BOSETTI FREDERICK C. KALMBACH ERNST A. MEVISSEN RUDOLF E. VOGELSBERGER ATTORNEYS United States Patent 3,365,186 APPARATUS FOR SELECTIVELY POSITIGNING A DEGASSING VESSEL Richard S. Bosetfi, Glenwillard, Frederick C. Kalmbach and Ernst A. Mevissen, Coraopolis, and Rudolf E. V0- gelsberger, Pittsburgh, Pa., assignors to Dravo Corp rafion, Pittsburgh, Pa., a corporation of Pennsylvania Filed Aug. 24, 1964, Ser. No. 391,714 Claims. (Cl. Zen-34) ABSTRACT 0F THE DESCLGSURE This disclosure relates to vacuum degassing and particularly to an apparatus for selectively positioning a degassing vessel for using and repairing the vessel and associated equipment. The vessel is vertically positionable by means of motor driven screw jacks connected to a yoke which engages a flange on the vessel, the yoke being movable in guide rails mounted on a support structure. The vessel is connected to a telescoping vacuum line which comprises a fixed portion and a movable portion connected to the vessel and slidably communicating with the fixed portion. An inflatable, water-cooled seal is provided between the two portions. The vessel can be disconnected from the fixed portion and a cover placed over the open end thereof. Additive bins communicate with the vessel in a similar fashion through a telescoping duct.

In vacuum degassing, molten metal in a ladle is conveyed to a degassing area and positioned beneath a degassing chamber or vessel having depending tubular extensions, the lower ends of which are then immersed in the molten metal. The metal is then circulated from ladle to vacuum vessel back to the ladle by forcing the metal up one or more of the tubes into the degassing vessel and back to the ladle through one or more of the tubes so that undesirable gases in the metal are removed in the vacuum vessel and exhausted.

Certain difficulties and safety hazards as well as expensive apparatus are involved in the degassing of the molten etal, especially steel. These difficulties and hazards arise particularly from the bringing together of the degassing vessel and the container of metal into operating relation, and their separation upon completion of the degassing process.

The present practice involves lifting the entire container, such as a ladle with perhaps 75 to 300 tons of molten steel, into operating relation with the tubular extensions of the degassing vessel after the ladle has been positioned beneath the vessel. This necessarily involves heavy, expensive, and relatively slow acting mechanisms, and presents a safety hazard in lifting so large a mass of molten metal above the floor level. Moreover, in degassing equipment of this kind, there is usually one degassing vessel in use with a standby vessel connected with the same vacuum line, but blanked off from the line, so that if, during degassing, one vessel should fail for any reason, the second may be brought into use. Present equipment may involve considerable delay beyond a safe margin of time to effect this change. Another difliculty arises from the need to have ready access to the tube extensions for replacing the lower terminals thereof, as well as the need to quickly remove the degassing vessel from operating position for relining or mechanical repair.

With the present invention the degassing vessel is moved vertically with respect to the molten metal. This achieves greater safety and involves much lighter and less expensive and less cumbersome equipment, since the vessel is much lighter than a ladle of metal and contains only a small quantity of metal at any one time. To accomplish the movement, telescoping tubular vacuum lines are provided between the vessel and the fixed permanent line. The lines are provided with slip joints for complete separation of the lines when the vessel is moved beyond its normal operating stroke, thus providing a means for rapidly removing or replacing a vessel. Desirably, these slip joints are made vacuum tight during operation by inflatable seals that may be quickly inflated or deflated and which are suitably protected from the intense heat of the environment in which they must operate. A door or valve which may be quickly operated is provided for closing or blanking off the vacuum line to a vessel which has been removed.

Accordingly, a principal object of our invention is to provide a degassing apparatus of unique construction which is safer, cheaper, faster and easier to operate than apparatus heretofore available.

Another object is to provide a novel degassing apparatus of unique construction and to provide an apparatus which facilitates operation, maintenance and repair of the vessel and associated equipment.

Another object is to eliminate the need for raising and lowering a ladle of molten steel by providing a means for raising and lowering the degassing vessel in a vacuum degassing system.

Further objects are to provide vacuum line seals for a degassing system so that the vessel may be raised and lowered, to provide seals which permit rapid connection and disconnection of joints in the vacuum lines and provide a means for rapidly and completely blanking off a degassing vessel from its associated vacuum line.

These and other objects will be more fully understood by reference to the following drawings, wherein:

FIG. 1 is a general view of a degassing station and associated equipment with a ladle positioned beneath the vessel;

FIG. 2 illustrates more or less schematically the degassing vessel in raised position for permitting a ladle to be positioned beneath the vessel; the vacuum line is shown in telescoped position;

FIG. 3 is similar to FIG. 2 but the vessel is lowered into operating relation with a ladle of metal;

FIG. 4 is similar to FIGS. 2 and 3 but the vessel is shown fully lowered for maintenance or removal and the vacuum line is completely separated with the seal door positioned over the stationary portion of the line;

FlG. 5 is a plan view of the vessel drive mechanism and also shows the seal door swung away from the vacuum line;

FIG. 6 is a detail plan view of the rails and guide channels;

FIG. 7 is a cross section or" the vacuum line slip joint and seal; and

FIG. 8 is a cross section of the seal door in closed position over the stationary portion of the vacuum line.

In the drawings showing an embodiment of our invention 10 is a trackway along which a ladle car or support 11 is horizontally movable to a degassing station designated generally at 12. There is an elevated vertical supporting stand or structure 13, comprised of a structural steel framework, located alongside the trackway 10 at the degassing station. The support stand 13 includes parallel vertical guide channels 14 of the cross sectional shape shown in FIG. 6. There is a cradle or yoke 15 which has spaced parallel lower arms 16 and is movable vertically in the guides 14. These arms 16 overhang the ladle when it is moved to the degassing station.

The degassing vessel 1'7 is a refractory lined chamber having at least one upflow tube 18 at the bottom, at least one downflow tube 19 and a gas exhaust or outlet duct through which gases are withdrawn. The vessel 17 is disposed between the horizontally spaced ower arms 16 of the yoke which engage the underside of the flange 21 to support the vessel 17 over the ladle. The side of the vessel 17 nearest the supporting stand 13 rests against a crosspiece 22, which extends between the two arms 16 to assist in keeping the vessel 17 in the vertical position. Each arm 16 of the yoke 15 is suitably afiixed to one flange of a vertical l-beam or rail 23 which extends substantially the vertical height of the yoke 15. The other flanges of the rails 23 slidably engage the channels or guides 14 which are fixed to the stand 13. The inner faces of the guides 14 have suitable bearing surfaces or wear plates 24 which engage the rails 23. Preferably the guides 14 are shaped to permit lateral expansion of the yoke and stand.

The yoke 15 also has two upper arms 25 disposed on either side of the vessel 17. Ball screw jacks 26 are suitably mounted on these upper arms 25. The jacks 25 extend vertically upward and lie in a vertical plane substantially through the center of gravity of the vessel. The length of the jacks 26 must be sufiicient to permit the maximum stroke desired which may be twelve feet or more in some instances. A typical vessel may have a working stroke of about 4 feet, but for maintenance purposes the stroke may be about 12 feet to lower the vessel to a maintenance platform. The screw jacks 26 are driven by a rotating nut which is driven by a motor 27 (FIG. 5) through suitable reduction gears. The motor is actuated and controlled by remote means (not shown), and is mounted on the rigid structural framework or support stand 13 adjacent the vessel 17. The jacks 26 are driven from a common shaft 28 to insure equal movement. The drive mechanism is equipped with suitable fail-safe features (not shown) for locking the vessel in position when the drive motor is cut off for any reason, such features being well known to those skilled in the art.

The movement of the vessel 17 necessitates some type of movable or slip joint in the vacuum line 29. The vacuum is created by the use of steam jets 30 (FIG. 1), and is maintained at a level on the order of 100-40O microns. The high temperature environment and high vacuum required presents a difiicult sealing problem.

When the vessel 17 is in the raised position as in FIG. 2, the movable portion 32 of the vacuum line 29 is telescoped into the stationary portion 31 for a distance approximately equal to the working stroke of the vessel 17.

When the vessel is lowered into position for degassing (see FIG. 3) and vacuumizing is to commence, the upper end of the movable portion 32 of the vacuum line 29 attached to the vessel is near the opening of the larger diameter stationary portion 31 of the line.

An inflatable pneumatic seal 33 surrounds the outer periphery of the movable inner line 32 and seals against the inner wall of the outer stationary line 31. The seal, which is shown in greater detail in FIG. 7, may be made of rubber or other suitable material.

As shown in FIG. 7 the telescoping portions of the vacuum line have spaced double wall constructions to form passageways for circulation of a coolant which passes through suitable inlets and outlets (not shown). This coolant protects the inflatable seal 33 from the high temperature environment. Removed from the upper end of the movable portion 32 of vacuum line 29 there is a seal-mounting annulus 35 fixed to the outer wall 32a of the movable portion 32. The inflatable seal 33 has a lip 36 around its inner circumference which fits snugly in a conforming recess in the annulus 35 to hold the seal 33 in place (FIG. 7). The annulus 35 also has ports 37 forming a passageway for air from a suitable source (not shown). The seal 33 has a solid annular portion 38 on its outer periphery, such that when the seal is inflated (as in dotted lines of FIG. 7), the solid portion 38 engages the inner wall 31a of stationary vacuum line 31 to farm" a seal for the slip joint between the stationary and movable portions of the vacuum line.

When the vessel 17 is completely lowered as in FIG. 4 and it is desired to operate the second vessel (not shown) in a two vessel installation operated from the same vacuum system, it is necessary to blank off the vacuum line to the inoperative vessel. For this purpose, a seal valve or door 39 is provided. This door 39 pivots about a vertical axis adjacent to and parallel to the stationary portion 31 of vacuum line 29, the axis being external to the circumference of the vacuum line (FIG. 5). The door 39 (FIG. 8) has a plate 40 with an annular ring 35a which ring has an outer diameter somewhat less than the inner diameter of the vacuum line 31. The seal 33a is mounted in the ring 35a in essentially the same manner as heretofore described in connection with the slip joint between the stationary and movable portions of the vacuum line. The door 39 is attached to the shaft 41 and operated by an air cylinder 42 or other suitable mechanical means to impart the necessary rotating and reciprocating motions to the door 39 for positioning the door over the open end of the stationary line.

There are hoppers or bins 43 (FIG. 1) positioned above the vessel 17 which contain additives which can be added to the metal in the vessel through the duct 44 which opens into the vessel 17. The duct 44 is also provided with a slip joint for easy separation from the vessel and to permit the additive bins 43 to be mounted to the stand 13, as shown in FIG. 1, and not on the vessel as is the present practice. Thus the vessel drive mechanism is relieved of the extra Weight of the additive bins 43. No seal is necessary in the additive duct slip joint because the additives are positively fed from rotary type valves 45 which provide the necessary seal between the vessel 17 and the bins 43.

Operation A ladle of molten steel, e.g., from a basic oxygen furnace shop, is transferred on a ladle car or the like to a position beneath the vessel 17. The drive mechanism is actuated to lower the vessel 17 so that the tubes 18 and 19 are immersed in the steel. The vessel 17 actually lowers by gravity at a rate controlled by the speed at which the screw jacks are driven and by the friction between the rails 23 and guides 14.

The vessel is stopped at the end of its Working stroke (about 4 feet) so that the vessel 17 and associated equipment are in the position shown in FIG. 3, with the tips of the tubes of the vessel immersed in the metal.

During the lowering, the vacuum line 29 and vessel 17 are at atmospheric pressure and the seal is deflated. When the vessel is in proper position, the seal 33 is inflated and vacuum drawdown begins. The metal is then degassed and additives are supplied as required from the bins 43.

After degassing is completed, the vessel 17 is returned to atmospheric pressure, the seal 33 is deflated and the drive mechanism actuated to raise the vessel. As the screw jacks 26 are raised, they carry the yoke 15 which in turn supports the vessel. The vessel is raised sufiiciently to permit removal of the ladle to the position shown in FIG. 2 with the vacuum line telescoped as shown. The ladle is then removed and the vessel is ready for another cycle.

If it is desired to remove the vessel 17 for maintenance, the vessel is lowered to the position shown in FIG. 4, completely separating the movable portion 32 of vacuum line 29 from the stationary portion 31. If the vessel is to be removed from the stand, no other disconnecting is required except for a few quick disconnect lines not here involved.

If it is further desired to operate a second vessel (not shown) from the same vacuum manifold while the vessel 17 is so lowered or removed, the seal door 39 may be 5 positioned across the now open end of the stationary portion 31 of vacuum line 29 (FIG. 4).

Air cylinder 42 is actuated to lower the shaft 41, to which the door 39 is attached, for a suificient distance to clear the depending stationary line 31. The door 39 is then rotated into position directly beneath the open end of the stationary line 31, then raised to cover the opening, after which the seal 33a is inflated to form a vacuum tight seal between the door and the stationary portion 31 of vacuum line 29 as shown in FIG. 4.

While we have disclosed one specific embodiment of the invention, it is apparent that numerous variations and modifications in the construction and arrangement of parts may be made without departing from the scope and spirit of our invention.

We claim:

1. Apparatus for degassing molten metal, comprising,

(a) a degassing station Where a vessel of molten metal to he degassed may be positioned,

(b) a supporting structure adjacent the degassing station,

(c) a degassing vessel mounted on the supporting structure overhanging the degassing station and having a plurality of tubes projecting from the bottom thereof,

(d) a vacuum line,

(e) means for moving the degassing vessel vertically,

and

(f) a gas exhaust connection on the vessel, telescopingly sealed into the vacuum line for enabling vertical movement of the degassing unit while communication with the vacuum line is maintained.

2. The apparatus as defined in claim 1 wherein the gas exhaust connection comprises a vertical duct which is shorter than the maximum vertical travel of the degassing vessel, whereby said connection may be selectively disengaged from the vacuum line.

3. The combination as defined in claim 1, including,

(a) at least one additive bin mounted on the supporting structure above the vessel, and

(b) an additive duct connecting the vessel to the bin, the duct having telescoping portions, one attached to the bin and the other to the vessel, for enabling vertical movements of the vessel while communication with the additive bin is maintained.

4. The combination as defined in claim 3, wherein the portion of the duct attached to the vessel is shorter than the maximum vertical travel of the vessel, whereby said portion may be selectively disengaged from the portion attached to the bin.

5. In a vacuum degassing apparatus, in combination,

(a) a vacuum degassing vessel,

(b) means associated with said vessel for imparting vertical movements thereto,

() a vacuum line leading to said vessel, said line comprising,

(l) a stationary portion, and

(2) a movable portion attached to said vessel,

(3) one of said portions being slidable within the other for a distance at least equal to the working stroke of said vessel,

(d) an inflatable sealing member attached to one of said portions intermediate the confronting walls of said stationary and movable portions, and

(e) means inflating said sealing member to form a vacuum tight seal between the confronting walls of said stationary and movable portions.

6. In a vacuum degassing apparatus, in combination,

(a) a vacuum degassing vessel,

(b) means associated with said vessel for imparting vertical movements thereto,

(c) a vacuum line leading to said vessel, said line comprising,

(1) a stationary portion, and

(2) a movable portion attached to said vessel, said portion being slidable within said stationary portion for a distance at least equal to the working stroke of said vessel,

(d) an inflatable sealing member attached to and surrounding the outer wall of said movable portion intermediate the confronting Walls of said stationary and movable portions, and

(e) means inflating said sealing member whereby the outer periphery of said sealing member engages the confronting inner wall of said stationary portion to form a vacuum tight seal between said stationary and movable portions of said vacuum line.

7. In a vacuum degassing apparatus of the type described, in combination,

(a) a vacuum degassing vessel,

(b) means associated with said vessel for imparting vertical movements thereto,

(0) a vacuum line leading to said vessel, said line comprising,

( 1) a stationary portion, and

(2) a movable portion attached to said vessel, said portion being slidable within said stationary portion for a distance at least equal to the Working stroke of said vessel,

(d) an annular member attached to and surrounding the outer wall of said movable portion intermediate the confronting walls of said stationary and movable portions, said member having a radial recess therearound,

(e) an inflatable sealing member disposed in said recess, and

(f) means inflating said sealing member whereby the outer periphery of said sealing member engages the confronting inner wall of said stationary portion to form a vacuum tight seal between said stationary and movable portions of said vacuum line.

8. In a vacuum degassing apparatus, in combination,

(a) a vacuum degassing vessel,

(b) means associated with said vessel for imparting vertical movements thereto,

(0) a vacuum line leading to said vessel, said line comprising,

(1) a stationary portion, and

(2) a movable portion attached to said vessel, said portion being slidable within said stationary portion for a distance at least equal to the working stroke of said vessel,

(3) both stationary and movable portions having spaced double walls to form passageways for the circulation of coolant therethrough,

(d) an inflatable sealing member attached to and surrounding the outer Wall of said movable portion intermediate the confronting Walls of said stationary and movable portions,

(e) means inflating said sealing member whereby the outer periphery of said sealing member engages the confronting inner Wall of said stationary portion to form a vacuum tight seal between said stationary and movable portions of said vacuum line, and

(f) means circulating coolant through the passageways in said stationary and movable portions for cooling said sealing member.

scribed, in combination,

(a) a vacuum degassing vessel, (b) means associated with said vessel for imparting vertical movements thereto, (c) a slip jointed vacuum line associated with said vessel, said line comprising,

(1) a stationary portion and (2) a movable portion attached to said vessel, (3) one of said portions being slidable within the other,

(4) said movable'portion being separable from said stationary portion when said vessel is sufficiently moved,

(d) means associated with said stationary portion for blanking oil the open end thereof when said vessel is so moved, comprising,

(1) a door,

(2) an inflatable sealing member attached to said door,

(3) means operatively connected to said door for positioning the latter over said opening, and

(4) means for inflating said sealing member, said sealing member being so positioned on said door so as to engage said stationary portion when inflated to form a vacuum tight seal between said portion and said door.

10. In a vacuum degassing apparatus of the type described, in combination,

(a) a vacuum degassing vessel,

(b) means associated with said vessel for imparting vertical movements thereto,

(c) a slip jointed vacuum line associated with said vessel, said line comprising,

(1) a stationary portion and (2) a movable portion attached to said vessel,

(3) one of said portions being slidable within the other,

(4) said movable portion being separable from said stationary portion when said vessel is suificiently moved,

(d) means associated with said stationary portion for blanking off the open end thereof when said vessel is so moved, comprising,

(1) a door,

(2) means operatively connected to said door for positioning the latter over said open end in closed position,

(3) an annular member attached to said door, said member being disposed within said opening adjacent the inner wall of said stationary portion when said door is in closed position, said memher having a radial recess therearound,

(4) an inflatable sealing member disposed in said recess,

(5) means inflating said sealing member whereby the outer periphery of. said member engages the confronting inner Wall of said stationary portion to form a vacuum tight seal between said portion and said door.

References Cited UNITED STATES PATENTS 2,606,046 8/1952 Bonner et al 34--242 2,862,701 12/1958 McFea-ters 266-35 2,988,444 6/1961 Hurum 53 3,154,404- 10/1964 Lorenz 26634 3,205,810 9/1965 Rosenak 266-35 X 3,223,397 12/1965 Young 266-34 3,202,450 8/1965 Servis 29491 J. SPENCER OVERHOLSER, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

E. MAR, Assistant Examiner.

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