Patent Application
20200318208
This invention is related to the general field of discharge ports on ladles, furnaces and tundishes, and more specifically to a thermal lance for unplugging a clogged molten metal vessel discharge port.
Discharge ports in molten metal dispensing systems at times can fail to open specifically upon an initial opening attempt, either through the clogging of the nozzle or tap hole fill material or hardened metal in the dispensing port, thereby inhibiting the flow of motel metal out of the vessel. The inventor of the instant application has developed several solutions over the years to assist in unclogging the plugged discharge port, including the inventions disclosed in U.S. Pat. Nos. 4,450,986; 4,746,037; 4,787,142; 4,877,161; 5,544,695; 7,537,723 and 7,563,407, the disclosures of which are incorporated herein by reference in their entirety.
In U.S. Pat. No. 4,450,986, a telescoping lance assembly includes a cylindrical housing that encloses a free-floating hollow metal tube. High pressure oxygen (on the order of 100 psi) is ported through the housing to propel the tube upwardly into the obstruction and to sustain burning as the combustible material is ignited. The tube is partially filled with magnesium wires or low carbon steel wires as the primary combustible material.
In U.S. Pat. No. 4,746,037, the telescoping lance assembly includes a flared bottom and a combustible collar at the top. The flared bottom is wider than the opening in a bushing located at the top of the housing to keep the tube from falling out of the housing. The tube is filled with magnesium wires or low carbon steel wires intertwined with steel wool to allow oxygen flow and to provide high surface area for combustion. The combustible collar includes a cardboard sheath wrapped around a low temperature blasting fuse and the exposed ends of the wires and steel wool. This construction provides a reliable ignition.
U.S. Pat. No. 4,877,161 discloses an improved lance assembly with a double telescoping mode to provide greater extension into a deep discharge port without the need for elongating the housing. The lance assembly includes a cylindrical housing with a port to admit pressurized oxygen. Inside the housing is either one or two free floating tubes. The tube (when single) or the uppermost tube (when dual) contains combustible magnesium or low carbon steel wires as the combustible material. The tube is crimped into the wires at the top and bottom of the tube to prevent the wires from moving forward or backward inside the tube. The tips of the wire extend out of the top end of the tube and they may be capped with an igniter covered by tape.
In another prior art lance assembly, the telescoping tube is made of stainless steel to provide a lower rate of consumption than the more combustible material of the thermal lance inside of it. The tube may have a flared base or a base flange to keep it centered in the housing, and the housing may include a bushing near the top end to prevent the tube from completely exiting the housing. The combustible material of the lance is a combination of thin cylindrical rod made of low carbon sheet metal that is roll-formed into a cylindrical rod that allows oxygen to flow axially through the rod. Rods of this type, and the process of making them, are described in U.S. Pat. No. 4,787,142. They are used as electrodes in exothermal cutting of metal and are commonly called burning bars or slice rods. They can be obtained from welding supply distributors under the brand name ARCAIR. The axial oxygen flow and increased surface area as compared to a solid bar or a hollow tubular bar provide for a rapid ignition and for burning in the presence of high temperature and oxygen flow.
The rod is surrounded by a low carbon steel sheath to provide greater rigidity and more mass of combustible low carbon steel. The sheath has an inner bore slightly greater than the outer diameter of the rod and an outer diameter less than the inner diameter of the stainless steel tube. The rod extends about ¾ inch to 1½ inches beyond the end of the sheath and several inches out of the opposite end. One end of the sheath is welded to the rod where the longer end of the rod extends such that the rod and sheath move together as a combustible lance within the telescoping tube. The top end of the tube can be crimped and filled with a steel wool (not shown) and can include a low temperature blasting fuse. This lance design provides greater combustible mass and more rigidity than the prior lances filled with steel or magnesium wires.
U.S. Pat. No. 7,563,407 discloses an improved thermal lance tip on a lance assembly. The lance assembly includes an outer low carbon steel sheath having an inner diameter. An inner rod is disposed in a sheath having an internal bore and a thin cylindrical rod that is roll-formed from low carbon steel sheet. The rod is sized for conforming fit in the bore of the tube and has a length dimension that is longer than the length of the tube. The rod is inserted into the bore of the tube and allowed to move axially within the tube under propulsion of the pressurized oxygen to allow the rod to be burned at a rate independent of the burn rate of the sheath. One or more apertures in the tube restrict the flow of oxygen until the rod is ignited. An 0 ring located near the fuse protector of the lance housing keeps the lance from moving during routine handling and storage.
The existing thermal lances can, at times, be difficult to ignite. A need exists for an improved thermal lance that facilitates ignition.
A telescoping thermal lance assembly is disclosed for use in unplugging a vessel discharge port. The telescoping thermal lance assembly includes a housing with an upper end that has an opening. An oxygen inlet port is located on the housing spaced apart from the open end. The oxygen inlet port is configured to connect to a supply of pressurized oxygen.
A cylindrical extension tube is disposed within the housing and extends partially out through the opening in the upper end of the housing. The extension tube has an open top and a closed bottom opposite the open top with a sidewall extending between the open top and the closed bottom. The extension tube has an inner diameter defining a cylindrical interior cavity, and an aperture extending through the sidewall or the closed bottom for permitting a flow of oxygen to enter into the interior cavity. The extension tube is slidingly disposed within the housing and configured to slide at least partially out of the opening in the upper end of the housing when a supply of pressurized oxygen is channeled into the inlet port.
The assembly includes an elongated cylindrical hollow lance tube made from a combustible material. The lance tube has an axial length with first and second ends. The lance tube has a cylindrical sidewall defined by an outer wall having an outer diameter and an inner wall having an inner diameter. The sidewall has a wall thickness between the outer and inner walls. The lance tube has a longitudinal axis. The lance tube being is slidingly disposed within the interior cavity of the extension tube and configured to slide at least partially out of the open top of the extension tube when a supply of pressurized oxygen is channeled into the aperture.
A slice rod is located within the inner wall of the lance tube. The slice rod being formed from low carbon steel.
A cap is attached to the open top of the extension tube, spaced apart from the tip of the lance tube. The space below the cap and above the tip of the lance tube defines an igniter section.
A tubular blow-out preventer sleeve is located in the igniter section above the tip of the lance tube and inside the extension tube. The sleeve has an outer diameter less than the inner diameter of the extension tube, and a wall thickness that is wider than any gap between the outer diameter of the lance tube and the inner diameter of the extension tube.
In one embodiment the sleeve has a bottom that rests against an upper edge of the lance tube.
The sleeve preferably has a wall thickness of at least 1/64 inch.
The sleeve is preferably made from a combustible material. In an embodiment, the combustible material is low carbon steel.
There is preferably steel wool located in the igniter section.
The cap preferably includes a hole and a fuse extends from outside the cap through the hole into the igniter section.
The telescoping thermal lance assembly may include a plurality of wires inserted into an upper end of the slice rod in close proximity to the cap. The wires being made from low carbon steel. The wires extend into oxygen passageways in the slice rod and protrude from the upper end of the slice rod so as to temporarily inhibit oxygen flow into the igniter section.
The foregoing and other features of the invention and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive.
For the purpose of the illustrating the invention, the drawings show a form of the invention which is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and instrumentalities shown in the drawings.
The present invention relates to an improved thermal lance for unplugging a vessel discharge port, for example, in a refractory lined ladle. As shown in
As noted above, the inner lance assembly 10 (lance tube 14 and lance rod 12) and tube 16 are disposed within the outer housing 1. A conduit 18 communicates pressurized oxygen to the interior of the housing 1. When the apparatus is placed in line with an obstructed discharge port and an oxygen supply is opened, the oxygen flows through the conduit 18 and into the housing 1 raising the axially displaceable extension tube 16 toward the obstruction in the discharge port. Oxygen flows around and into the interior or the raised tube 16 through aperture 15 to facilitate rapid burning upon ignition in the vicinity of the obstruction, as is well known in the field.
As extension tube 16 telescopes out of housing 1, lance tube 14 telescopes out of the tube 16. In addition, lance rod 12 telescopes out of lance tube 14. The telescoping extension tube 16 is preferably made of stainless steel or other high carbon steel to provide a lower rate of consumption than the more combustible material of the thermal rod 12 and lance tube 14 which are located inside extension tube 16. As tube 16 slides upward, the base flange 15 contacts the bushing 19 at the uppermost end of the housing 1 thereby preventing the extension tube 16 from exiting the housing 1.
As discussed above, the combustible lance assembly 10 includes tube 14 and lance rod 12, both made of low carbon steel formed into a cylindrical rod that has substantial mass and surface area, yet allows oxygen to flow axially between and through the lance tube 14 and rod 12. The axial oxygen flow and increased surface area provide rapid ignition and burning in the presence of high temperature molten metal and oxygen flow.
Referring to
The bullet tip 60 includes a hole 62. A low temperature blasting fuse 64 preferably extends through the hole 62 into the igniter section 50. The fuse 64 protrudes out from the cap as shown to facilitate lighting.
In order to temporarily reduce the oxygen flow during ignition, a plurality of fine wires 66 are inserted into the slice rod or burning bar 12. The wires are preferably made of low carbon steel and configured to ignite when exposed to the burning fuse 64 and steel wool. The wires 66 are inserted in a short distance, preferably approximately ½ inch into the oxygen passageways in the slice rod or burning bar and protrude out of the slice rod approximately ¼ inch so as to be in close proximity to the fuse 64. As should be apparent, the wires 66 work in conjunction with the steel wool or other combustible material in the igniter section 50 to provide additional ignition sites and reduce oxygen flow to further improve ignition reliability.
It has been determined that sometimes the heat and pressure during combustion can cause the side wall of the extension tube 16 above the lance tube 14 to blowout. Accordingly, the present invention incorporates a tubular blow-out preventer sleeve 70 in the igniter section 50 above the tip 30 of the lance tube 14 inside the extension tube 16. The sleeve 70 is preferably made from stainless steel, carbon steel or combustible material, with an outer diameter slightly less than the inner diameter of the extension tube 16 so that it can slip snugly in. The sleeve 70 preferably has a wall thickness of about 1/64 inch, thereby providing the ignition zone 50 with increased protection against blowout.
The incorporation of the preventer sleeve 70 not only adds lateral strength to the extension tube 16, but also prevents inadvertent compression of the steel wool during shipping. The inventor has determined that shipping can sometimes cause the lance tube 14 to move toward the cap 60 compressing the steel wool. This can lead to a gap forming between the fuse 64 and the steel wool which can lead to reduced ability of the steel wool igniting. Similarly, it is sometimes necessary to test the ability of the thermal lance assembly to extend. In those cases the user applies pressurized oxygen to test the sliding of the tubes without lighting the fuse. This can cause the lance tube 14 to compress the steel wool.
The present invention overcomes those issues by providing a stiffened ring of combustible material in the ignition section 50 to inhibit or prevent relative movement between the lance tube 14 and the cap 60.
As used herein, the term “engage” is intended to both direct physical engagement through one or more components as well as operative engagement.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening.
All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not impose a limitation on the scope of the invention unless otherwise claimed. The various embodiments and elements can be interchanged or combined in any suitable manner as necessary.
The use of directions, such as forward, rearward, top and bottom, upper and lower are with reference to the embodiments shown in the drawings and, thus, should not be taken as restrictive. Reversing or flipping the embodiments in the drawings would, of course, result in consistent reversal or flipping of the terminology.
No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. There is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalent.
The present application is related to and claims priority from U.S. Provisional Application No. 62/830,063 filed Apr. 5, 2019, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62830063 | Apr 2019 | US |
