US3220716A - Roof jet - Google Patents

Description

United States Patent 3,220,716 ROOF JET Raymond E. Armstrong, Clark, Joseph M. Burke, New

ll'ionmouth, and Edward M. Holub, Piainfield, Ni,

assignors to Union Carbide Corporation, a corporation of New York Filed June 14, 1961, Ser. No. 117,102 3 Claims. (Cl. 266-34) The present invention relates to an improved jet device for introducing a treating fluid into a molten bath. It relates more particularly to an apparatus for directing a plurality of high velocity fluid streams toward the bath surface at a close range.

The use of oxygen and/or other treating fluids by the steel industry to speed up production is increasing every year. Not only are these treating gases used extensively in the final stages of processes such as open hearth refining, but they are also used, especially oxygen, in the initial stages of the process to speed up melting of the charge by flame enrichment. In order to fully and most economically utilize the lances which conduct these treating gases into the bath, it is necessary to provide such lances with adequate means for countering the furnace atmosphere of high temperatures and molten splatter. Generally, lances of the type herein described are lowered through the roof of a metallurgical furnace to within the range of a few inches to a few feet from the bath surface or metal charge. It is, of course, necessary for operations under these conditions to incorporate into such injection devices a cooling system adequate to draw off the excessive heat imparted to the lance, especially the lower or nozzle portion positioned closest to the bath.

Since the lance nozzle includes one or more, and preferably a plurality of orifices for directing gas into the furnace, the cooling of that lower portion has presented many problems. Also, during any gas injection period, the molten bath will become highly agitated with the result that small, high velocity particles of slag and molten metal will usually be projected in random directions about the furnace. Many of these particles tend to fly upwardly toward the lance, some of which either enter the exposed orifices or else strike the lance outer walls and face. The flying particles in many instances remain molten after contacting the lance surface and thence proceed to flow down the sides thereof to eventually reach the forward face. Frequently this molten stream or molten particles become aspirated by the high velocity oxygen jets toward the orifices which have been found in many instances to become completely blocked due to these molten deposits.

It is therefore an object of the present invention to provide an apparatus for treating the charge in a metallurgical furnace, said apparatus being particularly adapted to resist the detrimental effects of excessive furnace temperature and splatter from the molten bath.

A further object is to provide a device of the type described having means to prevent scarfing of the lance internal walls due to the impingement against said walls of high velocity particles of metal and slag.

In brief, the present device contemplates a roof lance for introducing high velocity flows of a treating fluid such as oxygen into a molten bath. The lance itself consists of an inner elongated conduit extending substantially the entire length of the device for feeding a cooling liquid toward the lower or discharge end. A tube outwardly spaced from said conduit defines an annular passage for conducting oxygen toward the lance lower end. A casing tight annular seal.

spaced outwardly from said tube provides a second annular passage coextensive with the tube to provide a return path for the coolant liquid. A nozzle, sealably engaging the lower ends of the respective conduit, tube and casing, is provided with outwardly radiating passages for communicating the coolant water feed and water return passages. Said nozzle is further provided with a plurality of constricted orifices circularly arranged with openings thereof at the nozzle forward face, and in communication with the annular oxygen conducting passage. A smooth surface, scarf resistant metallic shield member surrounds the inner conduit toward the lower end thereof at a point adjacent the inner openings of the oxygen orifices. The nozzle lower face, normally exposed to a metal bath, is formed with a generally flat surface, said surface being recessed slightly and encircled by a peripheral lip which is coextensive with the casing outer surface.

A removable manifold sealably enclosing the upper ends of the respective tubular members is provided with means for introducing oxygen to the jet, and for circulating coolant liquid through the passages therefor.

Referring to the figure, a preferred embodiment of the present invention is designated geenrally at 10 and comprises a centrally positioned elongated conduit or tube 12 which extends substantially the length of the lance. The upper end of said conduit 12 is slideably received in the first of several substantially concentric annular openings formed into the lower surface of manifold 14. A resilient seal ring 16 positioned at the inner of said concentric manifold openings, is outwardly deformed by the registering wall of said conduit 12 to provide a fluid The seal maintains a tight connection between the respective members in spite of subsequent movement between the conduit and the manifold due to thermal expansion and contraction. An inlet 18, may be connected by a suitable conduit to a source of plant service water or other fluid which is normally utilized for cooling purposes.

A cylindrical tube 20, surrounding conduit 12 and outwardly spaced therefrom is slideably received in a second of said concentric annular openings in manifold 14. Said second opening, as shown in the drawing, comprises a passage 22, which in turn may be connected at port 25 to a source of oxygen or other fluid to be conducted toward the lance forward end for injection into a molten bath. This second concentric manifold opening may likewise be provided with a resilient seal ring 24 such that outward compression of tube 20 will afford an annular fluid tight seal between the mating surfaces of the tube and manifold during expansive movement.

A third tubular member or casing 26 is positioned outwardly of tube 20 and is of a sufficiently large inner diameter to define an annular passage 28 for the return flow of coolant fluid from the lance forward end. The casing may be fixedly positioned with respect to manifold 14 by any suitable fluid tight means adapted to the purpose but a preferred method is by threadably engaging said casing and manifold in the outer of the manifold concentric openings. The annular water return passage 28 opens into a chamber 29 formed into said manifold, which chamber may be connected through a suitable conduit to the plant service water thereby completing the lance cooling water cycle.

The lower ends of the respective tubular members are concentrically positioned with relation to each other by a nozzle piece shown generally as item 30. This initial portion of the lance is preferably made of a heat conductive metal such as copper and is a highly critical component of the apparatus since it is most adversely affected by furnace heat and bath splatter. It has been found in practice generally that the nozzle is the portion which usually determines the lance usable life. The illustrated nozzle comprises three substantially concentric tubular sections 32, 34 and 36 which are so arranged and constructed as to abuttingly engage and be fluid tightly connected to the elongated tubes 12, and casing 26 respectively. One method of joining these members is by welded or brazed circumferential joints which may be cut apart to permit replacement of the nozzle section in the event of damage thereto.

The noule lower wall is so constructed and provided with means for both circulating coolant fluid and for delivering flows of treating oxygen toward the bath. As seen in the drawing, said lower wall comprises a panel 38, the lower or outer face 40 of which is exposed to the molten bath. This face according to the invention is positioned substantially perpendicular to the lance central axis and normally in a plane parallel to the bath face. A center chamber 42 receives downwardly flowing water from the conduit 12 to realize maximum cooling effect and thence redirects the water outwardly through a plurality of radially positioned passages 44 which communicate said chamber 42 with the annular water return passage 28. The radial passages 44 are preferably formed into and integral with the nozzle in such a manner as to position at least one of said passages intermediate each adjacent pair of oxygen orifices 46. These orifices will be hereinafter described in greater detail.

An annular shoulder 48 integral with the nozzle between the adjacently positioned tubular sections 32 and 34 constitutes the lower wall of the annular oxygen passage 23. A plurality of the above mentioned constricted orifices 46 communicate said passage 23 with the nozzle forward face 40 for directing high velocity jets of oxygen toward and into the molten bath. These orifices are preferably circularly arranged with respect to the nozzle face and so spaced apart as to provide the maximum number of orifices yet permit room therebetween for the radial coolant passages 44.

The orifices 46, as shown, may be outwardly divergent from the lance center axis to afford a desirable pattern of oxygen impingement on the bath surface. Since these orifices are directed generally toward the bath, they are, of course, subjected to a great deal of splatter in the form of metal or slag particles which are ejected from the bath reaction zone at a high velocity. These high velocity particles tend to strike the lance and adhere to the surface thereof, in many instances however the particles are ejected in such. a path that they enter the oxygen orifices and impinge against the inner wall of conduit 12.

Conduit 12 is not a structural member of the apparatus in the sense that it supports any appreciable load as does the casing 26. Consequently, this conduit is normally provided with a relatively thin wall. It has been found that over an extended period of time the frequency with which the high velocity metal or slag particles strike the conduit wall has caused considerable damage and eventual puncturing of the conduit especially through a scarfing of the wall surface. To obviate or lessen the detrimental effect and scarfing caused by the flying particles, the lower end of conduit 12 according to the invention is provided with a thin shield or elongated sleeve 50. A preferred embodiment of the shield consists of a cylindrical member closely fitted about the conduit outer wall. The collar, as shown extends rearwardly from wall 48 and surrounds that portion of the conduit which would ordinarily lie in the path of entering slag particles. The collar is usually made of a smooth surfaced, scarf resistant material such as brass which tends to deflect and render harmless the above-mentioned flying fragments.

The harmful eifects of bath splatter and furnace heat are further neutralized by the present nozzle construction which includes the relatively flat exposed face 40. This face according to the invention disposed in a plane approximately parallel to the bath surface. Said face, which constitutes the outer wall of panel 38, is substantially uniform in thickness and peripherally defined by a downwardly projecting lip or rim 52. The rim, as shown, is preferably coextensive With the outer surface of casing 26 and serves a very useful and highly desirable purpose.

As previously mentioned, the molten slag and metal which are ejected from the bath tend to strike and adhere to the lance outer surface in the vicinity of the nozzle. These particles not only tend to build up on the nozzle outer surface but also if they remain molten, flow downwardly toward the nozzle face.

Since the oxygen orifices 46 generally terminate near the lance face outer edge, there has always been a propensity to aspirate the downwardly flowing molten streams toward the orifice outlet. By providing the present lip 52, aspiration of the molten stream is overcome since the molten streams or particles will fall back into the bath before being drawn toward the high velocity oxygen jets.

The circumferential lip 52 to be most effective should be contiguous with the casing outer surface, and provide an extension thereto. It has been found that a lip extending between about A to A of an inch down from the face 40 is suflicient to overcome the aspirating action. Also when said lip is properly arranged with relation to the orifice 46, the downwardly flowing high velocity oxygen jets will be guided to some extent into a circular pattern on the bath surface thereby achieving a clear, slag free treating area immediately below the lance. A further advantage derived by use of the extended lip is realized when the lance is inadvertently lowered so as to come into contact with the heated and partially fused metal charge. Ordinarily such. contact would result in the lance and the metal charge becoming fused. By employing the thin forward projecting lip, which offers only a scant surface along which fusion may take place, such fusing is minimized.

While the presently disclosed lance described a preferred embodiment of the fluid injection device, it is understood that modifications and changes might be made in the apparatus by one skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In a lance for injecting a flow of treating fluid into a molten bath, which lance comprises an inner conduit for conducting a coolant fluid to the lance forward end, a tube outwardly spaced from said conduit defining an annular passage for treating fluid, a casing surrounding said tube defining a return passage for said coolant fluid, means enclosing the upper ends of said conduit, tube and easing, a nozzle fluid tightly engaging the lower ends of said conduit, tube and casing respectively for directing said coolant and treating fluid, an orifice extending through said nozzle communicating the nozzle face with the annular treating fluid passage, said orifice terminating in said annular passage at a point adjacent said inner conduit, the improvement therewith for protecting said inner conduit from high velocity particles of metal and slag being ejected from the bath and which enters said orifice, which improvement comprises a scarf resistant shield surrounding the lower portion of said conduit whereby said high velocity particles upon entering said orifices may impinge against said shield and be deflected away from the conduit wall.

2. In a lance substantially as described in claim 1 wherein the shield comprises a cylindrical scarf resisting metallic member contiguous with the conduit outer surface extending rearwardly from said orifice to shield said 5 6 surface from impingement thereagainst of high velocity References Cited by the Examiner particles of metal and slag entering through said orifice. UNITED STATES PATENTS 3. In a lance substantially as described in claim 1 wherein the shield surrounding the conduit comprises a 2,836,411 5/1958 Allel- 3,020,035 2/1962 HlIldS et al 26634 smooth surfaced cylindrical member positioned against 5 said conduit surface to receive and deflect high velocity particles of metal and slag which enter said orifices from MORRIS WOLK Pnmary Exammer' the molten bath. RAY K. WINDHAM, Examiner.

Claims (1)

1. IN A LANCE FOR INJECTING A FLOW OF TREATING FLUID INTO A MOLTEN BATH, WHICH LANCE COMPRISES AN INNER CONDUIT FOR CONDUCTING A COOLANT FLUID TO THE LANCE FORWARD END, A TUBE OUTWARDLY SPACED FROM SAID CONDUIT DEFINING AN ANNULAR PASSAGE FOR TREATING FLUID, A CASING SURROUNDING SAID TUBE DEFINING A RETURN PASSAGE FOR SAID COOLANT FLUID, MEANS ENCLOSING THE UPPER ENDS OF SAID CONDUIT, TUBE AND CASING, A NOZZLE FLUID TIGHTLY ENGAGING THE LOWER ENDS OF SAID CONDUIT, TUBE AND CASING RESPECTIVELY FOR DIRECTING SAID COOLANT AND TREATING FLUID, AN ORIFICE EXTENDING THROUGH SAID NOZZLE COMMUNICATING THE NOZZLE FACE WITH THE ANNULAR TREATING FLUID PASSAGE, SAID ORIFICE TERMINATING IN SAID ANNULAR PASSAGE AT A POINT ADJACENT SAID INNER DUICT, THE IMPROVEMENT THEREWITH FOR PROTECTING SAID INNER CONDUIT FROM HIGH VELOCITY PARTICLES OF METAL AND SLAG BEING EJECTED FROM THE BATH AND WHICH ENTERS SAID ORIFICE, WHICH IMPROVEMENT COMPRISES A SCARF RESISTANT SHIELD SURROUNDING THE LOWER PORTION OF SAID CONDUIT WHEREBY SAID HIGH VELOCITY PARTICLES UPON ENTERING SAID ORIFICES MAY IMPINGE AGAINST SAID SHIELD AND BE DEFLECTED AWAY FROM THE CONDUIT WALL.

Images