Metal making lance tip assembly
A metal making lance tip assembly including a tip face member having a plurality of outlets, a plurality of nozzles corresponding in number and in communication with the tip face member outlets, and a coolant flow baffle member for directing coolant flow around the nozzles. The lance tip assembly further includes both a generally centrally disposed coolant fluid diverting protrusion and a plurality of radial vanes at the inner surface of the lance tip face member, which vanes preferably extend essentially the entire axial distance between the inner surface of the lance tip face member and a lower surface of the coolant flow baffle member and essentially the entire radial distance from the central protrusion to an annular coolant fluid return passageway.
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The present application claims the benefit of U.S. Provisional Patent Application No. 60/794,258, filed Apr. 21, 2006, which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTIONThe present invention relates in general to metal making equipment and in particular to metal making lances.
BACKGROUND OF THE INVENTIONIn many metal making processes, water-cooled lances are inserted into a furnace vessel to perform desired metal processing functions. For instance, in steelmaking processes a water-cooled lance is inserted into a steelmaking vessel (e.g., a basic oxygen furnace (BOF), electric arc furnace (EAF), etc.), to promote melting, decarburization, refining and other processes useful in converting iron-containing scrap material within the vessel into steel. A typical lance may inject gaseous materials such as oxygen, hydrocarbon gas and/or inert gas at high velocity at various times to achieve desired treatment of the charged material (scrap and hot metal) and/or maintenance of the interior of the vessel. Some lances may also inject particulate carbon and/or lime (or other substances) to achieve desired properties in the steel ultimately produced.
Water-cooled lances generally comprise an adapter portion, an elongated barrel portion connected at a first end thereof to the adapter portion and a lance tip portion connected to a second end of the barrel portion.
The adapter portion comprises at least one inlet for receiving the gaseous and/or particulate matter to be injected into the furnace vessel, which matter will hereinafter be generally referred to as “active material.” The adapter portion also includes a water inlet and a water outlet for circulating pressurized cooling water throughout the lance.
The barrel portion comprises at least three substantially concentrically arranged metal, typically steel, pipes for communicating the cooling water and/or active material(s) between the adapter portion and the lance tip portion. The outermost and first innermost pipes normally define an annular water return passageway for conveying coolant water from the lance tip portion to the adapter portion. The first and second innermost pipes normally define an annular water delivery passageway for conveying coolant water to the lance tip portion from the adapter portion. And, the interior of the second innermost pipe (and any additional pipes arranged interiorly thereof) defines at least one passageway for conveying active material from the adapter portion to the lance tip for injection into the furnace vessel.
The lance tip portion usually comprises an assembly having one or more parts which may be secured by welding, soldering or the like to the concentric pipes of the barrel portion. The lance tip assembly comprises at least one nozzle in communication with the at least one active material passageway of the barrel portion for injecting or discharging the active material into the furnace vessel. The tip assembly further comprises passage means for connecting the water delivery and return passageways of the barrel portion to one another. So constructed, water or other coolant fluid may be continuously circulated through the lance to cool the lance, especially the lance tip assembly which is exposed to the greatest temperatures during lance operation. Indeed, if coolant water is not effectively conveyed through the lance tip portion then the assembly may become non-uniformly heated. This, in turn, may lead to so-called “hot-spots” or “burn-through” sites which often result in premature failure of the lance tip.
A common practice by which the steelmaking lance manufacturing industry has sought to impart cooling to the lance tip assembly is to provide a generally centrally disposed protrusion or dimple at the inner surface of the tip face member of the tip assembly. The object of such protrusion is to direct coolant water radially outwardly through the interior space of the lance tip to cool all areas of the outer working surface face of the lance tip. The water-diverting protrusions have assumed an assortment of sizes and shapes and have met with varying degrees of success for their intended purposes. Examples of such protrusions may be found in U.S. Pat. Nos. 3,224,749; 3,525,508; 3,525,509; 3,823,929; 3,827,632; 4,083,539; 4,083,541; 4,083,542; 4,083,543; 4,083,544; 4,106,756; 4,322,033; 4,432,534; 4,702,462; 4,951,928; 6,234,406 and U.S. Reissue Pat. No. 28,769, as well as United Kingdom Pat. Nos. 1,190,137 and 1,255,082.
U.S. Pat. No. 4,417,721 proposes an alternative means for improving coolant water flow across the inner surface of a lance tip. In particular, a plurality of intricately configured radial water flow passages are provided between a lower surface of a coolant water baffle member and the inner surface of the lance tip face member. The radial flow passages are defined by and located between flow vanes of uniform thickness.
U.S. Pat. Nos. 3,322,419 and 3,337,203 and United Kingdom Pat. No. 1,255,082 combine a centrally disposed protrusion and a plurality of radially arranged coolant flow vanes at the inner surface of the lance tip face member. However, in each of these designs the vanes do not extend either (1) essentially the entire axial distance or height between the inner surface of the lance tip face member and the lower surface of a coolant flow baffle member or (2) essentially the entire radial distance from the central protrusion to the annular coolant fluid return passageway. The considerable radial or axial coolant flow gaps in these designs permit cross flow between adjacent coolant flow passages at the inner surface of the lance tip face member. It is believed that such cross flow produces eddy currents and dead spaces in coolant water flow which could result in the formation of hot spots at the outer working surface of the lance tip face member.
An advantage exists, therefore, for a metal making lance tip assembly which is comparatively easy to assemble and durable in operation and which provides substantially uniform cooling of the working face of the lance tip via structural features that promote high coolant water flow and velocity throughout the tip.
A further advantage exists for a metal making lance tip assembly having a structurally reinforced face for improved operating performance and service life.
SUMMARY OF THE INVENTIONThe present invention provides a lance tip assembly for a water-cooled lance. In general, the assembly includes a tip face member having a plurality of outlets, a plurality of nozzles corresponding in number and in communication with the tip face member outlets and with a corresponding number of inlets provided in an active material well member, a coolant baffle member for directing coolant flow around the nozzles, and a tip face member support post connecting the tip face member and the active material well member for providing structural support to the tip face member during lance operation.
Unlike other lance tip assemblies, the lance tip assembly of the present invention further includes both a generally centrally disposed coolant fluid diverting protrusion and a plurality of radial vanes at the inner surface of the tip face member, which vanes extend essentially the entire axial distance between the inner surface of the lance tip face member and the lower surface of the coolant fluid flow baffle member and essentially the entire radial distance from the central protrusion to the annular coolant fluid return passageway. The resultant construction provides high velocity and essentially eddy and void free coolant fluid flow across the inner surface of the lance tip face member which, in turn, uniformly cools the lance tip face member and greatly enhances the service life of the lance tip assembly.
Other details, objects and advantages of the present invention will become apparent as the following description of the presently preferred embodiments and presently preferred methods of practicing the invention proceeds.
The invention will become more readily apparent from the following description of preferred embodiments thereof shown, by way of example only, in the accompanying drawings wherein:
Referring to the drawings wherein like or similar references indicate like or similar elements throughout the several views, there is shown
An exemplary, although not limitative, procedure for assembling lance tip assembly 10 is as follows. The various components of assembly 10 may be formed of metal or metal alloys including, without limitation, copper, brass, steel, stainless steel and the like, as may be appropriate for the intended function(s) or desired characteristic(s) of the components (e.g., structural strength, thermal conductivity, etc.). One end of support post 24 is welded to the uppermost portion of a centrally located protrusion 28 provided on inner surface 30 of tip face member 12. Protrusion 28 is described in detail in connection with the discussion of
Although shown and described as separate components assembled into a collective whole, it is also contemplated that nozzles 16, active material well member 20 and baffle member 22 may be a single component. For example, they may be formed as a unitary casting of copper or brass in a manner similar to that described in U.S. Pat. No. 6,217,824, the disclosure of which is incorporated herein by reference thereto. It will be appreciated that by forming nozzles 16, active material well member 20 and baffle member 22 as a single component, several of the above-described assembly steps may be eliminated.
As seen in several of the figures, protrusion 28 is preferably located coaxially with the central longitudinal axis 26 of the lance tip assembly. The contour of the protrusion 28 is preferably substantially conical, although it may have a somewhat convex or concave profile in relation to the central longitudinal axis 26. According to a presently preferred embodiment, the profile of protrusion 28 is substantially conical whereby the circumferential wall of the protrusion diverges from the central longitudinal axis 26 at an angle α (
Additionally, the outside or working face of tip face member 12 is preferably formed, either during or after manufacture, with a recess 48 (
A second set of vanes, identified by reference numeral 32b, are preferably circumferentially spaced midway between adjacent vanes 32a. As best seen in
The provision of vanes 32a and 32b radiating from protrusion 28 establishes highly controlled coolant water flow paths that enhance the ability of the lance tip assembly to convey water at high velocity and more uniformly cool the lance tip. Additionally, the vanes provide structural reinforcement for the lance tip face and nozzles, thereby resulting in enhanced lance tip performance and service life.
As part of the present invention, a “coolant reinforcement ratio” or “CRR” with respect to the vanes is defined as T/H. Without intending to be bound by theory, it is believed that a CRR of approximately 0.3 contributes to the superior cooling characteristics of the lance tip assembly according to the present invention versus conventional lance tip assemblies known in the art.
Turning to
A known failure mechanism in a typical BOF lance tip is center face wear caused by slag and/or metal entrained in the furnace gasses. In the present invention, a recess 48 of appropriate depth “d” in relation to dimension “D” may substantially reduce the exposed area of the tip working face which reduces face wear. In contrast, a relatively flat tip face would have a high DPR ratio. In any design, however, the final recess profile is dependent on a compromise between the requirements of the internal water distribution profile, nozzle leg spacing and face thickness.
Similar to a beneficial CRR (and, again, without intending to be bound by theory) it is believed that a beneficial DPR contributes to the superior cooling characteristics of the lance tip assembly according to the present invention versus conventionally constructed lance tip assemblies known in the prior art (as observed by the inventors through empirical comparative experimentation).
The following are among the many advantages of a lance tip assembly constructed according to the present invention:
1. higher momentum oxygen jets resulting in increased height or distance of the lance from the metal bath (which, in turn, translates to reduced potential for damage to the lance during operation);
2. reduced nozzle exit erosion;
3. less decay of the oxygen jets resulting in improved bath mixing and lower slag FeO;
4. less decay of the oxygen jets resulting in lower oxygen consumption per ton of steel produced;
5. extended lance service life without increasing slag FeO;
6. increased cooling water flow (by reducing eddy currents and other flow disturbances);
7. lower temperature differentials in the lance tip;
8. improved cooling water efficiency (through convection) by virtue of the radial vanes;
9. improved cooling water distribution and velocity by virtue of the flow-redirecting central protrusion;
10. increased cooling water volume via a less restrictive design that results in lower friction (more specifically, a metal making mill water cooling system is rated at a given output for a given pressure drop across the lance (a/k/a “pump curve”); by reducing the tip pressure drop, pump output increases without any additional energy requirements;
11. reinforced tip face by virtue of the radial vanes and the support post, thereby resulting in reduced tip face distortion;
12. reinforced nozzles by virtue of the radial vanes, thereby resulting in reduced tip distortion;
13. reduced exposed area at the center of the tip face by virtue of the central recess generally corresponding in shape to the central protrusion; and
14. reduced exposed area for steel/slag adherence to the center of the tip face (which may result in localized burning) by virtue of the central recess generally corresponding in shape to the central protrusion.
Although the invention has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention as claimed herein. For example, although the illustrated lance assembly is constructed with a single centrally located active material delivery conduit, it is possible that the lance may contain more than one such passageway for delivering similar or dissimilar active materials. Likewise, it is also possible that the coolant water inlet passageway may disposed interiorly rather than exteriorly of one or more of the active material passageway(s).
Claims
1. A metal making lance tip assembly comprising:
- a tip face member having an inner surface, an outer surface and at least one active material discharge outlet;
- at least one nozzle for delivering active material to a furnace vessel through said at least one active material discharge outlet;
- a coolant fluid baffle member for directing coolant flow around said at least one nozzle;
- a coolant fluid diverting protrusion provided on said inner surface of said tip face member; and
- a plurality of vanes provided on said inner surface of said tip face member, said vanes extending essentially the entire axial distance between said inner surface of said lance tip face member and a lower surface of said coolant fluid flow baffle member and essentially the entire radial distance from said protrusion to a coolant fluid return passageway.
2. The assembly of claim 1 further comprising an active material well having at least one active material receiving inlet in communication with said at least one nozzle.
3. The assembly of claim 2 further comprising a post having an upper end connected to said active material well and a lower end connected to said coolant fluid diverting protrusion for providing structural support to said tip face member during operation of said assembly.
4. The assembly of claim 1 wherein said vanes have a height “H” and an average thickness “T” and wherein a beneficial cooling reinforcement ratio is attained when T/H is approximately 0.3 at any point along the radial extent of said vanes.
5. The assembly of claim 1 further comprising a recess formed in said outer surface of said lance tip face member in general alignment with said protrusion, wherein “D” is the diameter of a circle defined by the foremost projection of said outer surface circumscribing said recess, wherein “d” is the depth of said recess from the foremost projection of said outer surface to the deepest point of said recess, and wherein a beneficial dimple profile ratio is attained when D/d is approximately equal to 2.7.
6. The assembly of claim 1 wherein said vanes have a height “H” and a thickness “T”, wherein a beneficial cooling reinforcement ratio is attained when T/H is approximately 0.3 at any point along the radial extent of said vanes; said assembly further comprising a recess formed in said outer surface of said lance tip face member in general alignment with said protrusion, wherein “D” is the diameter of a circle defined by the foremost projection of said outer surface circumscribing said recess, wherein “d” is the depth of said recess from the foremost projection of said outer surface to the deepest point of said recess, and wherein a beneficial dimple profile ratio is attained when D/d is approximately equal to 2.7.
7. The assembly claim 1 wherein said protrusion is substantially conical and wherein a circumferential wall of said protrusion diverges from a central longitudinal axis of the assembly at an angle of between about 20°-50°.
8. A metal making lance tip assembly comprising:
- a tip face member having an inner surface, an outer surface and at least one active material discharge outlet;
- at least one nozzle for delivering active material to a furnace vessel through said at least one active material discharge outlet;
- a coolant fluid baffle member for directing coolant flow around said at least one nozzle; and
- a plurality of vanes provided on said inner surface of said tip face member, wherein said vanes have a height “H” and an average thickness “T” and wherein a beneficial cooling reinforcement ratio is attained when T/H is approximately 0.3 at any point along the radial extent of said vanes.
9. A metal making lance tip assembly comprising:
- a tip face member having an inner surface, an outer surface and at least one active material discharge outlet;
- at least one nozzle for delivering active material to a furnace vessel through said at least one active material discharge outlet;
- a coolant fluid baffle member for directing coolant flow around said at least one nozzle; and
- a recess formed in said outer surface of said lance tip face member, wherein “D” is the diameter of a circle defined by the foremost projection of said outer surface circumscribing said recess, wherein “d” is the depth of said recess from the foremost projection of said outer surface to the deepest point of said recess, and wherein a beneficial dimple profile ratio is attained when D/d is approximately equal to 2.7.
10. A metal making lance tip assembly comprising:
- a tip face member having an inner surface, an outer surface and at least one active material discharge outlet;
- at least one nozzle for delivering active material to a furnace vessel through said at least one active material discharge outlet;
- a coolant fluid baffle member for directing coolant flow around said at least one nozzle;
- a plurality of vanes provided on said inner surface of said tip face member, wherein said vanes have a height “H” and an average thickness “T” and wherein a beneficial cooling reinforcement ratio is attained when T/H is approximately 0.3 at any point along the radial extent of said vanes; and
- a recess formed in said outer surface of said lance tip face member, wherein “D” is the diameter of a circle defined by the foremost projection of said outer surface circumscribing said recess, wherein “d” is the depth of said recess from the foremost projection of said outer surface to the deepest point of said recess, and wherein a beneficial dimple profile ratio is attained when D/d is approximately equal to 2.7.
11. A metal making lance tip assembly comprising:
- a tip face member having an inner surface, an outer surface and at least one active material discharge outlet;
- at least one nozzle for delivering active material to a furnace vessel through said at least one active material discharge outlet;
- a coolant fluid baffle member for directing coolant flow around said at least one nozzle; and
- a coolant fluid diverting protrusion provided on said inner surface of said tip face member, wherein said protrusion is substantially conical and wherein a circumferential wall of said protrusion diverges from a central longitudinal axis of the assembly at an angle of between about 20°-50°.
Type: Application
Filed: Apr 19, 2007
Publication Date: Oct 25, 2007
Applicant: Berry Metal Company (Harmony, PA)
Inventors: Nicholas M. Rymarchyk (Cranberry Township, PA), George Cingle (Gibsonia, PA), Todd G. Smith (Grove City, PA)
Application Number: 11/788,251