US3025047A - Apparatus for the restraint and control of oxygen lances - Google Patents

Description

March 13, 196 K. REINFELD ET AL APPARATUS FOR THE RESTRAINT AND CONTROL OF OXYGEN LANCES 2 Sheets-Sheet 1 Filed Oct. 11, 1960 INVENTORS. ETC/I420 F. aes/vcwnz xuer EEINF'ELD. BY

2 Sheets-Sheet 2 QQOQP M.

their a 'rraP March 13, 1962 K. REINFELD ET AL APPARATUS FOR THE RESTRAINT AND CONTROL OF OXYGEN LANCES Filed Oct. 11, 1960 United. htates Patent @Hice 3,@Z5,M7 Patented Mar. 13, 1.962

Deiaware Filed Get. 11, 1960, Ser. N 61351 3 Claims. (Ci. 266--34) This invention relates to apparatus for an oxygen steelmaking converter, and more particularly, to apparatus for supporting a lance for supplying oxygen for such a converter.

It is typical in the art to use a long tube or lance to force oxygen into contact with the surface of molten pig iron in an oxygen converter as is required in conventional steelmaking to eliminate certain chemical elements (silicon, manganese, sulfur, carbon and phosphorus) from the pig iron. The lance is usually inserted through an opening in the upper end of a closed bottom converter, and a high velocity jet of substantially pure oxygen is forced downwardly against the surface of the molten metal in the converter from an orifice at the end of the lance.

By ejecting the oxygen at velocities in the transonic and supersonic ran es (velocities of Mach 2 are common) the effect is to cause this oxygen to strike the surface of the bath and initiate reactions with the metalloid impurities. These reactions in turn violently agitate the bath.

The violent agitation of the bath is due to the temperature and density differentials between that portion of the bath surface under the oxygen jet (primary reaction area) and the rest of the bath. In the reaction zone, temperatures close to the boiling point of iron prevail. Also, the evolution of CO is strongest in the immediate vicinity of this reaction zone. As a result, the froth and gases in the converter above the surface of the bath are in a whirling turbulence. It is to be expected, as is in fact the case, that under the combined influences of the reaction from the ejected oxygen blast and the buffeting action of the churning gases in the converter, the lance will be subjected to forces tending to produce violent rotating and rocking actions in the lance. These actions induce such severe vibrations in the lance as to pose the problem of supporting the lance so as to oppose these forces and minimize the vibrations whereby to effectively restrain and control the lance during the blowing operation.

Effective control of the lance during the blowing operation is desirable to permit accurate positioning of the lance with reference to the surface of the molten metal.

This positioning is ditlicult, however, because the level of the metal in the converter and the chemical analysis of the metal vary. In response to these fluctuating conditions, frequent changes in the positioning of the lance become necessary during each oxygen blowing period.

Apparatus for positioning and restraining the lance heretofore has consisted of a Wire rope hoisting device, a lance guide, and a clamp. The lance guide and the clamp are generally mounted on the top of the hood above an opening therein. Alternatively, they have been mounted on some structure adjacent the converter but completely independent of the lance itself as in the case of the hood-mounted clamp. Since the lance has a Water jacket thereabout and has hoses leading therefrom, the eccentric force of these attachments to the lance prevent the lance from hanging with the axis of the lance vertical. Therefore, in operation, the wire rope hoisting device lowers the eccentrically supported lance until the tip of the lance is engaged with the lance guide which positions the end of the lance for passage through the opening in the hood and, once properly guided, the lance is lowered to the desired position. Then the hoodrnounted clamp is closed about the lance to support and restrain it positioning the orifice of the lance at the desired distance above the surface of the bath. As often as or more times per day during the oxygen blowing periods it becomes necessary to change the relative position between the lance nozzle orifice and the top of the bath, each time requiring the engagement and disengagement of the hood-rnounted clamp.

Unfortunately, during the repositioning of the lance, the high velocity oxygen input must, of necessity, be reduced considerably or completely shut off since during this period the lance is substantially unrestrained against vibration. Thus, each time the hood-mounted clamp is released and then reengaged, the blowing operation is interrupted causing the timewise extension of this operation and resulting in a marked decrease in efficiency.

An added disadvantage is that the openin and closing of the hood-mounted or otherwise independently mounted clamp for each lance adjustment plus the maintenance occasioned by frequently occurring clamp failures also restrict the availability of the converter vessel itself for the blowing operations.

Although some devices heretofore have mounted clamps on structure other than the hood, in no case is the clamp so arranged as to continuously accompany the lance sup porting it through the repositioning thereof to obviate reduction of the oxygen blast.

Also, any clamping or guiding devices placed at the top of the hood must be cleared by the lance when it is withdrawn for charging or tapping. Therefore, the height of the building housing the converter operations must be increased in turn by the height of such clamping or guiding devices, a height of as much as 5 feet. The great expense occasioned thereby is a distinct drawback to the use of such an arrangement.

it is therefore, an object of this invention to provide an improved means for restraining and controlling the positioning of an oxygen lance.

It is another object of this invention to provide a guiding and restraining device for an oxygen lance to permit oxygen flow from the lance at full capacity throughout the oxygen blowing operation.

An additional object of this invention is to provide lance-handling equipment enabling a reduction in the height of the building required to house an oxygen steelmaking operation.

Still another object of this invention is to provide a device for the restraint and control of an oxygen lance in which the maintenance problem will be eliminated or greatly reduced.

This invention provides a novel apparatus for continuously restraining and controlling an oxygen lance com prising an elevated support, elongated guide means for defining a substantially vertical path of travel for the lance, the guide means being pivotally attached to this support to provide for swinging movement thereof in a horizontal direction, a lifting mechanism mounted on these guide means, a guide carriage restrained by the guide means for vertical reciprocation relative thereto and a lance releasably affixed to the guide carriage. The lance moves with the guide carriage to which it is rigidly clamped and the movement of the guide carriage in the guide means offers accurate control over the vertical positioning of the lance at any time.

In accordance with this invention, control of the lance is not hampered by clamping means mounted either at the point at which the lance passes through the hood or otherwise independently mounted. The guide carriage and the guide ways or tracks in which the guide carriage travels serve to support the lance in a vertical Q C position against the eccentric force from the weight of the hoses. These elements also oppose the rotation and rocking of the lance under the buifeting action within the converter While moving with the lance and continuously aligning and rigidly restraining it against vibration. Thus, there is no need for shutting off or cutting back the high velocity oxygen jet during the frequent lance repositionings. As a result, a marked decrease in the blowing time is effected with consequent increase in converter tonnage output.

Also, since the mechanism supporting the lance is at a greater distance from the heat of the converter and since it is necessary to unclamp the lance from the guide carriage only when a new lance is to be inserted, there is a marked decrease in the maintenance costs incurred with the present device. Since the failure of hoodmounted clamps usually occurs during the blowing operation, the present improvement serves to decrease the length of the blowing operation by the removal of these interruptions.

Other objects will cifically pointed out in greater description wherein:

FIGURE 1 is an elevational view showing the positioning of a preferred embodiment of this invention relative to the converter;

FIGURE 2 is a section taken on URE 1;

FIGURE 3 is an elevational view showing the guide be in part obvious and in part spedetail in the following line 2--2 of FIG- carriage-lance connection with the lower clamp pivoted to the open position, and

FIGURE 4 is a plan view showing the device of FIG- URE 1 swung to one side to permit charging or tapping of the converter.

As shown in FIGURE 1, this invention may be advantageously used with the closed bottom converter 11 in an oxygen steelmaking process. This invention may also be used for the steelmaking process in other types of furnaces as, for example, in an open hearth furnace. Furnace or converter 11 as illustrated herein is a conventional closed-bottom steelmaking oxygen vessel having an outer shell 12 with a basic refractory lining therefor composed of magnesia ramming mix 13 and tarbonded dolo-magnesia bricks 114.

Auxiliary equipment includes hood 16 for removing fumes and smoke from converter 11, and lance 17. Lance 17 is protected in a conventional manner by a water jacket, but for the sake of simplicity this structure has not been shown.

In accordance with this invention, clamping means to continuously accompany lance 17 is supplied, lance 17 being rigidly clamped to guide carriage or cradle 18 by placing lance 17 in semi-cylindrical recess 19 formed in cradle 18 and holding it in place by means of arcuate clamps 21. Clamps 21 are pivotally supported by pro jections 22 which are formed or welded on the body of cradle 18. When each clamp 21 is swung about pins 23 into the closed position, tongue-like projection 24 formed on the end of clamp 21 Swings between vertically spaced projections 26 and 27. Wedge 28 is then forced through slot 29 in each projection 26, through opening 31 in tongue 2.4 and slot 32 in each projection 27 to urge arcuate clamp 21 forceably against lance 17. Since there is at least a four-foot spread between the arcuate portions 21 the connection between lance 17 and guide carriage 18 is a very rigid one.

Carriage 13 is adapted for vertical motion on structural steel guide tracks 33 by means of a series of flanged wheels 34 and 36, which run on rails 37 and 38. Although not shown, the weight of carriage 18 and lance 17 can be partially offset by the use of a counter-balance. Guide tracks 33 are afiixed in a substantially vertical position by means of struts 39 and 41 which are pivotally connected to bearing brackets 42 and 43 by means of pins 44 and 46.

In the present illustration of the invention, carriage or cradle 18 is shown permanently mounted in tracks 33. However, it is but a simple expedient to permit carriage 18 to accompany lance 17 even while lance 17 is not positioned for vertical motion. Thus, it may be convenient for each spare lance to be supplied complete with a carriage permanently or semi-permanently affixed thereto. A hinged portion of tracks 33 can be provided having a hydraulic actuator to open it to permit entry of carriage 18 and thereafter to retain the hinged portion in closed position pending removal of carriage 13.

During the charging and tapping operations of the converter 11, the entire arrangement of guide tracks 33, guide carriage or cradle 18, and lance 17 with the actuating mechanism therefor may be easily swung to one side or the other, the pivotal connections being so designed as to permit a swing of at least As is shown in FIGURE 1, the load of the entire assemblage is transmitted to structural steel column 47 supported on girder 48 which is in turn supported on columns 49 and 51 placed at some distance from the converter 11 to avoid danger from slag and metal spills at yard level. Thus, the entire support for lance 17 is elevated or spaced a safe distance from converter 11. In addition to the aspect of safety, the proposed mounting of lance 17 requires less room on the operating floor 52 and also at yard level.

The mechanism for lifting lance 17 together with carriage 1% is best shown in FTGURE 4. A mounting plate 53 is provided as a support for the actuating mechanism including motor 5-1 coupled to motor reducer 56 which in turn drives hoist drum 57 to raise and lower lance 17. Since lance 17 is placed substantially at the center of gravity of carriage 18 and chain yoke 58 picks up at the center of gravity of the carriage-lance assembly, the arrangement shown permits an in-line lifting and lowering of lance 17 as well as in-line restraint and control thereof. The driving mechanism being affixed to mounting plate 53 moves with the guide tracks 33, carriage 18 and lance 17 to whichever position is assumed by pivoting the assembly about pins 44 and 46. Although not shown in the drawings, the guide tracks 33 are interconnected by bracing members to keep them parallel to each other and provide stiffer guide means.

In operation, once a new lance has been inserted into place in recess 19 and clamped firmly thereto by clamps 21, the lance 17 is rigidly held in substantially vertical position in spite of the weight of hoses 59 exerting an eccentric force theeron. In preparation for the blowing operation, once converter 11 has been charged, the entire assemblage of lance 17, carriage 18, and tracks 33 with the super-imposed lifting mechanism are swung over converter 11 and lance 17 is lowered through opening 61 in hood 16 until the end of lance 17 is properly positioned over the bath. The lowering is, of course, effected by playing out wire cable 62 from the hoist drum 57 which lowers carriage 18 with lance 1'7 rigidly affixed thereto. Whenever repositioning of lance 17 is required within converter 11, carriage 18 is moved carrying lance 17 with it to the new position and remaining at all times rigidly fixed to lance 17 firmly restraining it against the forces acting thereon to permit continuous blowing of the oxygen blast throughout the entire repositioning operation.

The typical oxygen steelmaking blow heretofore has lasted about 15 to 30 minutes, with as much as 3 or 4 minutes of this time being due to the lengthening of the blowing time as a result of oxygen in-put cessation or cutback during the repositioning of the lance. It may readily be appreciated that the present arrangement for continuously, rigidly restraining the lance 17 through the entire period of utilization of the lance, whereby no interruption of the oxygen blast need occur, will effect additional economies in this new art of steelmaking. Although the present invention contemplates an in-line arrangement for the control of the lance, should it be desired to use a cluster of lances some small eccentricity may be required to facilitate arranging the cluster.

In the present invention, the movement of lance 17 being limited to a given path by carriage 18 and tracks 33, limit switches (not shown) may readily be employed to control the extent of downward movement of carriage 1S and lance 17. Also, in the event that wire cable 62 should break, a positive stop (not shown) to prevent the downward movement of carriage 18 and lance 17 may be provided. The present invention readily lends itself to the application of such a safety measure due to the fixed vertical path of movement. Free-falling lances have been known to drop into the bath still spewing oxygen resulting in the burning through of the refractories and shell with consequent loss of metal and delays in operations. The possibility of loss of life from such an accident is sutliciently imminent to warrant the exercise of these safety measures for this reason alone.

Further, while the lance is inserted within the converter a build-up of spatter occurs thereon. Such a build-up often becomes so large and unwieldy as to interfere with the blowing operations. In the prior art lance suspension systems (eccentric hang from wire cables) as the buildup reached troublesome proportions it becomes necessary to remove the build-up material by pounding or by the use of a cutting torch. The present device, on the contrary, lends itself to the installation of a vibrator or rapping device (not shown) to apply sufiicient vibration to the rigidly supported lance while in place to shake loose the material striking the lance before it becomes solidified, permanent build-up.

Although the present disclosure shows a lance installation in which the entire assembly of carriage, lance, guide track, and lifting mechanism are pivoted to the side, it may be seen that the lateral movement of such entire assembly on a mono-rail, for example, is equally feasible.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

What is claimed:

1. Apparatus for introducing a high velocity jet of fluid into a furnace comprising in combination with an oxygen converter a support, a lance having a substantially rectilinear axis, vertically disposed interconnected guide tracks, means for pivotally attaching said guide tracks to said support, a lifting mechanism supported by said guide tracks, a carriage mounted in said guide tracks for vertical movement relative thereto, means on said carriage for rigidly afiixing the upper end of said lance to said carriage throughout repositionings of said lance in said furnace during the blowing cycle, and means interconnecting said carriage with said lifting mechanism for vertical repositioning of said carriage, lance and aflixing means along said guide ways.

2. Apparatus for introducing fluid into a furnace comprising in combination, an oxygen converter, an elevated support, a pair of vertical disposed interconnected guide ways offset from said support, means for pivotally mounting said guide ways on said support for swinging movement, a lifting mechanism mounted atop said guide ways, a lance having a substantially rectilinear axis, a carriage rigidly afiixed to the upper end of said lance throughout repositionings thereof in said furnace, said carriage being mounted in said guide ways for vertical reciprocation relative thereto, and means for suspending said carriage from said lifting mechanism with the center of gravity of the carriage and lance assembly substantially in line with the application of force by said lifting mechamsm.

3. Apparatus for introducing a high velocity jet of fluid into a furnace comprising in combination with an oxygen converter, an elongated lance having a substantially rectilinearaxis, an elevated substantially vertical support, a pair of rigidly interconnected vertically disposed tracks, means for pivotally mounting said tracks parallel to said support, a lifting mechanism mounted atop said tracks and pivotable therewith, a carriage having flanged wheels interposed between said tracks for vertical rolling movement relative thereto, means on said carriage rigidly aifixing the upper end of said lance to said carriage throughout repositionings thereof, the center of gravity of the carriage and lance assembly being substantially in line with the application of force by said lifting mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 2,822,163 McFeaters Feb. 4, 1958 FOREIGN PATENTS 220,279 Great Britain Feb. 19, 1925 716,856 Great Britain Oct. 13, 1954 1,166,807 France June 30, 1958 OTHER REFERENCES Jour. of Metals, pp. 396400, March 1953.

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