US2506598A

US2506598A - Apparatus for feeding gas into molten metal baths

Info

Publication number: US2506598A
Application number: US3668A
Authority: US
Inventors: Jr Evan A Johnson
Original assignee: Hydrocarbon Research Inc
Current assignee: Hydrocarbon Research Inc
Priority date: 1948-01-22
Filing date: 1948-01-22
Publication date: 1950-05-09
Anticipated expiration: 1967-05-09

Description

May 9, 1950 E. A. JOHNSON, JR 2,506,598

APPARATUS FOR FEEDING GAs INT0 MoLTEN METAL BATHs Filed Jan. 22, 1948' IN VEN TOR.

AGEN T Patented May 9, 1950 APPARATUS FOR FEEDING GAS INTO MOLTEN METAL BATHS Evan A. Johnson, Jr., New York, N. Y., assignor to Hydrocarbon Research, Inc., New York, N. Y., a corporation of New Jersey Applicationianuary zz, 194s, serial No. 3,668

5 Claims. l

This invention relates to apparatus for introducing a gas, such as oxygen or oxygen-enriched air, into a bath of molten metal.

The introduction of oxygen or oxygen-enriched air into a bath of molten metal, for example, molten iron in an open hearth furnace to accelerate the rate of reduction of the carbon content of the molten iron, has received and is receiving considerable attention by research personnel. In order to obtain satisfactory results it has been found necessary to introduce the oxygen beneath the surface of the bath of molten iron Where it will come into intimate contact with the carbon and effect its removal. Obviously the introduction of oxygen through a steel or iron pipe having its exit end disposed beneath the surface of the molten iron results in melting and/or oxidation of the pipe at a rate requiring rapid replacement of the pipe. In fact it has been suggested to use a long steel pipe or so-called lance, say about 20 feet long or longer, mounted on a carriage with one end immersed in the molten metal, the pipe being moved into the molten metal to replace the end portion as the latter is consumed while feeding oxygen through this pipe into the molten bath. Such equipment has many disadvantages, among which may be mentioned (1) it involves the use of a cumbersome carriage for the long lengths of pipe, which carriage and'lengths of pipe occupy the space near the open hearth furnace and therefore obstruct and otherwise interfere with the movement of the operators and furnace charging cars in the vicinity of the furnace, (2) it entails frequent interruption of the feed of the oxygen into the molten bath necessitated by the placement of new lengths of pipe on to the carriage and the connection of such pipe with the source of oxygen, (3) it involves arduous and time-consuming labor for servicing and operating the carriage which effects feeding of the length of pipe into the molten metal bath, (4) it necessitates stock piling long lengths of pipe in the vicinity of the molten metal bath, and

(5) only about 50% of the length of each lance is consumed before the lance is too short and must be discarded.

It is an object of this invention to provide apparatus for introducing a gas such, for example, as oxygen or oxygen-enriched air below the surface of a bath of molten metal, e. g., a bath of molten iron in an open hearth furnace, which apparatus is compact, requires little space in the vicinity of the bath, is simple to construct, is eilicient in operation and requires little attention by the operator.

Other objects and advantages of this invention will be apparent from the following detailed description thereof. Y

In accordance with this invention a reel having any desired length of metal pipe Wound thereon is disposed near the bath of molten metal. One end of the wound pipe is continuously or intermittently unwound from the reel by a feeding device which desirably straightens the pipe and causes the leading end to project into the bath of molten metal beneath the surface thereof. Gas is supplied to the other end of the pipe passing through the convolutions on the reel and flowing through the leading end of the pipe entering the bath beneath the surface thereof. The pipe is unwound at a rate corresponding to the rate at which the end of the pipe immersed in the bath of molten metal is consumed; for example, the pipe may be unwound at a rate of about 0.1 to 10 linear feet per minute.

The reel provides in compact form unusually long lengths of pipe, enough to permit introduction of the gas beneath the surface of the molten metal for several hours without interrupting the supply of gas. Furthermore, the reel and the feeding mechanism associated therewith occupy relatively little space in the vicinity of the bath and may be so disposed that they do not interfere with the movement of the operators. feeding mechanism associated with the reel automatically feeds straight lengths of pipe at the desired rate and effects straightening of the pipe as fed requiring practically no attention on the part of the operator except when the pipe on the reel has been consumed. The reel, if desired, may be so designed as to carry a length of pipe sumcient to last throughout the decarburization period, thus necessitating no replacement of the reel during the decarburization period, a fresh l reel preferably being installed at the commencement of a new heat.

In the preferred embodiment illustrated on the drawing the invention is shown incorporated in an oxygen feeding device for an open hearth furf nace and the description which follows will be confined to the present illustrated embodiment of the invention. It will be understood, however, that the novel features and improvements are susceptible to other applications such, for example, as feeding devices for feeding other gases than oxygen into baths of molten metal, including molten iron and other molten metals in electric, open hearth and other furnaces. Hence, the scope of this invention is not confined to the embodiment herein described.

Thel

3 In the accompanying drawing forming a part of this specification and showing for purposes of exemplication a preferred form of this invention without limiting the claimed 'invention to such illustrative instance. l

Figure 1 is a fragmentary vertical section through an open hearth furnace showing schematically in side elevation an oxygen feeding del vice associated therewith;

Figure 2 is an enlarged plan view of the ongen feeding device of Figure 1;

Figure 3 is a side elevation corresponding to the view of the oxygen feeding device show n in Figure 2.

Figure 4 is a vertical section taken in a plane v passing through line 4-4 of Figure 3.

Pipe I1 is wound on reel I8, desirably consisting of a pair of circular side plates I9 and 20 having openings 2| therein to reduce the weight of these plates. Each of the side plates is formed integral with or fastened to a hub 22 keyed to a hollow shaft 23. A cylindrical shell or pipereceiving member 24 is disposed, as shown in Figures 3 and 4, below the edges of the plates I9 and to provide a cylindrical trough 25 for re` ception of convolutions of the pipe I1. Plates I9 and 20 and member 24 may be cast in one piece or may be formed by welding the side plates to the pipe-receiving member 24. Trough 25 is made of suilicient depth to receive several convolutions of the pipe such as to provide a total length of pipe which will permit continuous introduction of oxygen into the open hearth furnace over a period of several hours, desirably throughout the entire melt.

A connecting pipe 26 has one end threaded into a threaded opening in shaft 23, extends therefrom and is provided with a coupling 21 at the other end. Coupling 21 joins end 28 of pipe I1 extending through opening 29 in pipe-receive ing member .24 to the connecting pipe 26. When winding pipe I1 on reel I8, end 28 is passed through opening 29, is coupled by coupling 21 forming a gas tight joint with connecting pipe 26 and then pipe I1 is wound on the reel I8 form ing the convolutions 30. A continuous uninter-` rupted passage is thus provided through hollow shaft 23, connecting pipe 26 and the interior of pipe I1 to the exit end I6 of this pipe.

The reel I8, it will be noted, consists of side plates I9 and 2U, pipe-receiving member 24, the convolutions of pipe thereon having end 2S of the pipe fastened through coupling 21 to pipe connection 26 and the hollow shaft 23 -with the interior of which pipe 26 communicates. This reel is removably mounted for rotation in a pair of bearing supports 3| and 32, desirably in the form` of plates resting ona suitable standard 33 disposed near the open hearth furnace III. Supports 3| and 32 may be bolted or otherwise secured to standard 33. A bearing 34 is disposed in the upper corner 35 of each of the bearing supports 3| and 32. Corner 35, it will be noted, is the corner remote from the open hearth furnace so that the reel can readily be removed from and replaced in its bearings 34. Desirably these bearings are of substantially U-shape permitting the ready insertion therein and removal therefrom of the hollow shaft 23 of the reel I8. Each of the bearing supports 3| and 32 is provided remove the reel I8 itis only necessary to removev bolts 39 and swing the latch members about their pivot 31.

Each of the bearing supports 3| and 32 is provided with a bearing arm 40 in which is rotatably mounted an idler roll 4I desirably having a concave surface as shown in Figure 2. Disposed adjacent to bearing arm 4|) and extending from each of the plates 3| and 32 is a bearing support ing member 42 in which is slidably positioned a bearing mounting 43 for a second idler roll 44. Desirably roll 44 is of the same size and shape as idler roll 4I but is positioned above idler roll 4| so that as the pipe I1 is caused to move between these two idler rolls, idler roll 4 I engages the under side of the pipe and idler roll 44 the top of the pipe. A threaded bolt 45 engages the bearing support 43 for the idler roll 44 and is employed to adjust the position of idler roll 44 with respect to xed roll 4| to exert the desired pressure on the pipe to effect straightening thereof as it is fed through the idler rolls 4I and 44 by the feeding mechanism hereinafter described. The idler rolls 4I and 44 thus function to straighten the pipe I1 as it is unwound from reel I8 so that the freev end of the unwound pipe is substantially free of kinks and extends in a substantially l straight line direction.

A pair of feed rolls 46 and 41, desirably of concave shape and serrated surface, are rotatably mounted in the bearing plates 3| and 32` next to idler roll 44. Keyed to the shafts of these feed rolls are a pair of

meshing gears

48 and 49. The shaft having gear 49 keyed thereto has also keyed thereto a drive gear 58 driven by a worm 5| on the armature shaft of a variable speed motor 52. Motor 52 is carried by a bracket 53 bolted or otherwise secured to bearing support 32. Motor 52, when energized, drives the feed rolls 46 and 41 at a selected rate of speed to feed pipe I1 to maintain the free end I6 thereof continually immersed in the body of molten iron I2. The linear rate of movement may vary from about 0.1 to l0 feet per minute, the exact rate depending upon continuous or intermittent feeding, the temperatureof the moltenmetal, the-type of pipe used, etc., and in all cases being so chosen that the free end I6 of the pipe is maintained beneath the surface of the molten bath.

.An oxygen supply pipe 54 is disposed contiguous to bearing pate 32 and is provided with a rotatable coupling 55 arranged to |be threadily or otherwise connected with end 56 of hollow shaft 23. 'I'he other end of this hollow shaft is provided'with a suitable plug 51.

In operation, a reel of steel pipe having end 28 connected through pipe 26 with hollow'shaft 23 is rotatably mounted in bearings 34, the latches 36 bolted in place and oxygen supply line 54 connected with end 56 of hollow shaft 23. End I6 of pipe I1 is then threaded through the straightening rolls 4I `and 44 into the bite between the feed rolls 46 and 41. Oxygen is then turned on and variable speed motor 52 energized to drive the

feed rolls

48 and 41. The action of the feed rolls unwinds the pipe from reel I8 rotating in u bearings 34, pulls the unwound pipe through straightening idler rolls 4I and 44 and projects the extending end IB through opening I5 into the bath of molten iron beneath the surface thereof. Since the reaction takes place at the exit end of the pipe where the exiting oxygen reacts with the contents of the molten metal bath, which reaction is exothermic, the highest temperature is in the locality'of the exit end. This end therefore melts first and by feeding the pipe at a controlled predetermined rate the end which melts is replaced so that the introduction of oxygen into the molten bath may be continued without interruption.

The melting steel pipe obviously does not impair the composition of the molten iron bath. When melting metals other than iron in which iron is an objectionable impurity, a pipe should be chosen of a metal which when melted does not result in the incorporation of objectionable impurities in the melt.

When the pipe has been unwound from the reel to the point where only about a single turn of pipe remains on the reel, motor 52 is deenergized, the feed of oxygen is stopped, coupling 21 is disconnected, motor 52 is again energized until the end of the pipe previously connected to coupling 21 has .passed through feed rolls ,45 and 41, and the terminal piece of pipe thus released from the feeding device of this invention is permitted to drop into the furnace or, if preferred, is withdrawn from the furnace and discarded. Coupling 55 is then disconnected, bolts 39 removed, latch members 36 swung open, reel I8 removed from its bearings 34 and replaced by a new reel. Alternatively, when the end of the pipe previously connected to coupling 21 has almost reached idler roll 4I, motor 52 is stopped, reel I8 is removed from its bearings 34, a new reel put in place and the leading end of the pipe thereon brought into contact with the terminal end of the pipe still held between the feed rolls 46 and 41. The two contacting pipe ends are welded together and thereafter Vthe feeding of pipe into the furnace may be resumed. After the pipe ends have been joined the flow of gas through lthe pipe and into the molten bath may again be initiated.

It is to be understood that Figure 1 is not a scaled drawing but represents schematically one illustrative arrangement of the feeding device of this invention and a furnace holding a molten metal bath. The feeding device is often so small relative to the size of the furnace that it can be mounted on a support or bracket fastened high on a wall of the furnace so that operators and charging cars may pass thereunder. As a specific example, areel about 5 feet in diameter and about l/2 foot wide, holding 32 turns of standard Vg-inch steel pipe (about 530 linear feet of pipe), is designed for use with a conventional open hearth furnace. If desired, the feeding device of this invention may be mounted above the furnace and the pipe fed into the molten bath through an opening in the roof of the furnace.

It will be noted this invention provides an improved apparatus for feeding a gas beneath the surface of a bath of molten metal, which apparatus is compact and notwithstanding this, can feed relatively long lengths of pipe, is simple in design and eillcient in operation, occupies little space so that it does not interfere with the charging equipment or the operators of the furnace, and requires little attention once the operation of the feed rolls is commenced until substantially all of the pipe has been consumed.

Since different embodiments of the invention can be made without departing from the scopeof this invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense. Thus while a cylindrical pipe has been shown in the drawing the invention comprehends pipe of other shapes. Accordingly, the term pipe" is used in the claims in a broad sense to include pipe of any desired cross sectional configuration.

What is claimed is:

1. Apparatus for feeding gas into a bath of molten metal beneath the surface thereof, which comprises a reel, a, metal pipe wound on said reel, a gas supply pipe communicating with one end of said wound pipe, and motor driven means for pulling said wound pipe from said reel and for feeding the other end of said pipe into the bath of molten metal to maintain the said other end of said pipe beneath the surface of the bath of molten metal.

2. Apparatus for feeding gas into a bath of molten metal beneath the surface thereof, which comprises a rotatable reel, a metal pipe wound on said reel to provide a plurality of convolutions of pipe thereon, a gas supply pipe communicating with one end of said pipe, motor-driven feed rollers for pulling said wound pipe from said reel, and means for straightening said pipe as it is pulled from said wheel, said feed rollers being constructed and arranged to feed the other end of said-`pipe into the bath of molten metal.

3. Apparatus for feeding oxygen into a bath of molten iron in an open hearth furnace, which comprises a rotatable reel, said reel having a hollow shaft, an oxygen supply line connected with said hollow shaft, a steel pipe wound on said reel, said pipe having one end communicably connected with said hollow shaft and having the otherend extending from said reel into the said bath of molten iron, motor-driven feed rollers to pull said wound pipe from said reel and to feed the said other end of said pipe into the said bath of molten iron, and means for straightening said pipe as it is pulled from said reel.

4. Apparatus for feeding oxygen into a bath oi molten iron in an open hearth furnace, comprising a support disposed near said open hearth furnace, a reel removably mounted in said support, said reel having a hollow shaft, a pipe receiving cylindrical portion. a plurality of convolutions of steel pipe mounted on said receiving portion, said steel pipe having one end extending through said pipe receiving portion and connected with said hollow shaft, and the other end extending in a substantially straight line direction into said open hearth furnace beneath the surface of the molten bath therein, an oxygen supply line communicably connected with said hollow shaft, a pair of straightening :rollersl disposed, one below and the other above said pipe between which pair of rollers the pipe passes, a pair of feed rollers for feeding said pipe to effect the unwinding thereof from said reel, the passage thereof through said straightening rollers and the feeding of the straightened pipe into said open hearth furnace, and a variable speed motor for driving said feed rollers to maintain the free end of said pipe immersed in the molten bath in said open hearth furnace.

5. Apparatus for feeding gas into a bath of molten metal, comprising a support disposed near said bath, a, reel removably mounted in said support, a metal pipe wound on said reel, one end of said wound pipe communicating with a sas supply pipe and the other end extending in a Number p substantially straight line direction into said bath. 1 188,377 a plurality of rollers and 9, motor associated 2'267175 therewith arranged to pull said wound pipe from 5 2'343899 said reel and to advance the said other end of said pipe in a substantially straight line direction l into said bath. Number EVAN A. JOHNSON. Jn. 492,317

REFERENCES CITED 'I-he following references are of record in the tile oi this patent: f

UNITED STATES PATENTS Name Date Jones June 20, 1916 Skriba Dec. 23, 1941 Groll Mar. 14. 1944 FOREIGN PATENTS Country Date Germany Ebb. 26, 1930