US3591160A

US3591160A - Blast device for steel converter

Info

Publication number: US3591160A
Application number: US739553A
Authority: US
Inventors: Pierre Leroy; Emile Sprunck
Original assignee: Forges De La Loire Comp D Atel
Current assignee: Compagnie des Ateliers et Forges de la Loire SA
Priority date: 1967-07-05
Filing date: 1968-06-24
Publication date: 1971-07-06
Anticipated expiration: 1988-07-06
Also published as: DE1783165A1; FR94892E; DE1758590B2; US3602435A; BE717073A; DE1758590A1; LU56316A1

Abstract

Device for supplying blast gas to the blowing orifices of the bottom of a steelwork converter, which comprises a plurality of header-forming tubes disposed either as concentric tores or in any other suitable manner, each header being adapted to supply blast gas to a number of bottom orifices, for example a row thereof, with self-stopping means for easily putting each tuyere out of service in case of abnormally rapid wear thereof. Small diameter pipes, formed to have flexibility to facilitate assembly and disassembly are used for the connection of the supply header tubes to the bottom orifices.

Description

United States Patent [721 Inventors Pierre Leroy Appl No. Filed Patented Assignee Priority BLAST DEVICE FOR STEEL CONVERTER 5 Claims, 5 Drawing Figs.

[1.8. CI 266/41, 266/30, 266/34 PT Int.Cl C211) 7/16, C2 1c 5/48 Field of Search 266/41, 34,

Primary xaminerJ. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Wendoroth, Lind & Ponack ABSTRACT: Device for supplying blast gas to the blowing orifices of the bottom of a steelwork converter, which comprises a plurality of header-forming tubes disposed either as concentric tores or in any other suitable manner, each header being adapted to supply blast gas to a number of bottom orifices, for example a row thereof, with self-stopping means for easily putting each tuyere out of service in case of abnormally rapid wear thereof. Small diameter pipes, formed to have flexibility to facilitate assembly and disassembly are used for the connection of the supply header tubes to the bottom orifices.

PATENTEHJUL 6l8'll 3591.160

SHEET 1 OF 4 I l L1 K 1 I i i m own m2? l I M: LEROY m i l E SPRUNCM.

PATENTEUJUL 6197i 3.591.160

sum 2 or 4 HERRE LEROY EN\lLE SPRUNC \NVENTOIS BLAST DEVICE FOR STEEL CONVERTER This invention relates to a device for supplying air to be blown through the bottom of a steel converter, this device being particularly advantageous when the blast pressure exceeds 3 bars or 43 p.s.i.

The conventional system for supplying air to the bottom of steelwork converters comprises a so-called blowing box consisting of a simple cylindrical and relatively shallow chamber of a diameter slightly greater than the diameter of the outermost circular row of tuyeres or blowing orifices. lts lateral wall comprises one or more large apertures through which the airblast is directed. This blowing box is bounded at the top by the baseplate supporting the converter bottom provided with blow holes, and at the bottom by a closing lid. By removing this lid access can be had to the blow holes in order to check their behavior in service and, if necessary, either clear them or on the contrary block them up on purpose in case their wear were deemed abnormally rapid in comparison with that of adjacent holes. The removal of said lid is also useful for replacing a worn bottom with a new one at the end of a run.

As a rule, this supply system is adequate for operating Bessemeror Thomas-process steel plants in which the blast pressure does not exceed 3 bars (43.5 p.s.i.).

However, if more recent steel-making processes are used, such as the blowing of pure oxygen or high oxygen air through orifices of relatively small diameter, in which it may be desired to produce blasts under pressures considerably higher than those conventionally used in Bessemer or Thomas processes which, as already pointed out, do not exceed 3 bars (43.5 p.s.i.), the conventional blowing box cannot be used since its operation would be attended by the following inconveniences:

a. The blowing box closing lid, of which the airtightness is already inadequate under service pressures of the order of 1.5 to 3 bars (21 to 43.5 p.s.i.), has a definitely poor airtightness when the pressure exceeds 3 bars (43.5 p.s.i. As an alternative, the number of tightening devices for example of the stud and key type may be increased, but in this case the opening and closing of this lid becomes a long and tedious operation. Moreover, the joint between the lid and the box must be provided with a plastic gasket and it is clear that along such a great circumference the resulting fluidtightness cannot be satisfactory unless the box and lid are really distortion free, a condition generally of short duration in the case of a new blowing box.

b. The use of blast pressures in excess of 3 bars (43.5 p.s.i.)

and even in excess of 12 bars (174 p.s.i.) is attended by a considerable multiplication of the risk of causing air leaks to take place between the bottom plate and the base of the tuyeres or blowing pipes, and therefore of suddenly causing the complete refractory bottom to blow up under the high air pressure. If the blowing box diameter exceeds 2 meters (6 feet 7 inches) the resultant of the pressure forces acting upon the bottom plate is very important. Thus, under a l2-bar (l74-p.s.i.) pressure this resultant is well above 375 tons. As a result, on the one hand a deformation of the baseplate and the lid is observed during the pressure increment period, and on the other hand fatigue strain appears between the compression and expansion phases.

It is the essential object of the present invention to provide a device for supplying an oxidizing blast to the blowing orifices or tuyeres at the bottom of steelwork converter which is free of the drawbacks of a conventional blowing box and capable of operating satisfactorily under pressures in excess of 3 bars or 43.5 psi.

To this end the present invention provides a device for supplying such an air or oxidizing blast to the blowing orifices disposed through the bottom of steelwork converters, said device consisting of a plurality of header tubes having either the shape of concentrically disposed tores, or any other suitable configuration, each header delivering air under pressure to a number of bottom orifices, for example those ofone row.

This invention may also have one or more of the following features taken separately or in any combination, and it is to be understood that the term air as used throughout this application is intended to include a pure oxygen or a high content oxygen mixture:

a. The airblast header assembly is mechanically detachable as a unit;

b. The airblast header assembly is welded to the bottom plate;

c. The airblast header assembly itself is fed with blast air from a single inlet, or from two or more inlets;

d. The supply of blast air to the headers is through or facilitated by, interconnecting ducts of which the number and contour are such that they ensure a uniform distribution of the air output to each blast tuyere of the set;

The supply headers and the interconnecting ducts are made of steel;

f. The supply headers and the interconnecting ducts are made of copper;

g. The set of supply headers is housed in a box, for example a conventional blast or blowing box, provided with a closing lid. The function of this box is to protect the headers as a whole, and also the members connecting these headers to the blowing orifices, against shocks or the projection of incandescent materials;

h. The supply headers are connected through flexible pipes to the blowing orifices fed therefrom;

i. The supply headers are connected to the blowing orifices through pipes of relatively smail diameter, such as copper pipes forming one or more turns or coils, in order to impart a certain elasticity thereto which may be useful during assembling and disassembling operations.

j. The flexible pipes as per (h) hereinabove or the small diameter pipes as per (i) are provided on at least one of their ends, on the blowing orifice side, or at either ends, with self-stopping unions adapted to close themselves automatically in a fluidtight manner when they are disconnected;

k. The blowing orifices are provided with copper tubes of relatively small diameter and adapted to be connected or disconnected by simply operating the end union of the corresponding flexible pipe or small diameter pipe;

1. The assembly consisting of each union as per (j) hereinabove, of the lower end of the copper tube lining each blowing orifice and of the bottom baseplate, is so arranged that if an accidental blast leakage took place as a consequence of the high pressure between the union and the lower end of the copper tube, it would be vented to the free atmosphere, so that it will not filtrate between the tube and the bottom plate.

m. if the supply headers are connected to the blowing orifices via flexible piping as per (h) or small diameter pipes as per (i), these headers are each disposed between two adjacent rows of blowing orifices, in order to free the access to these orifices for inspection and maintenance purposes in service, and also for disconnecting them in case of abnormally fast wear thereof in comparison with that of adjacent orifices;

n. Each header welded to the baseplate engages directly a row of blowing orifices and receives therethrough, in front of each orifice, a movable nozzle provided with a valve member, the axis of said nozzle and the axis of said valve being coincident with the axis of the corresponding blowing orifice;

o. In a device of the type set forth in paragraph (n) hereinabove, each metal tube, for example the copper pipe, constituting the blowing orifice of the converter bottom has a funnel-shaped lower end soldered or not to the plate supporting the bottom of the converter, and the nozzle has a semispherical upper end adapted to engage in a fluidtight manner the inner wall of said funnel so as to press same against said bottom plate;

. In a device of the type set forth in paragraphs (n) and (0) the hollow nozzle comprises coaxially to its upper end a cylindrical blowing orifice ending at the top with an outflared portion so that the successive hammerings of the upper end of the nozzle will not alter the diameter of the cylindrical portion and therefore the gas output controlled thereby;

. In a device of the type set forth in paragraphs (n), (p) hereinabove, the inner cavity of the nozzle which supplies air to the cylindrical orifice mentioned in paragraph (p), is adapted to communicate with the air under pressure contained in the header through a number of ducts of which the total cross-sectional passage area is calculated with a view not to restrict the gas output;

. In a device of the type set forth in paragraphs (n), (0) and (p) hereinabove, the valve member incorporated in the nozzle is a solid member mounted in the nozzle and provided with a ball valve at its upper end, said ball valve being adapted to engage a seat consisting of the edge of the cylindrical orifice of the nozzle mentioned in paragraph (p) hereinabove, when it is desired to discontinue the operation of the relevant tuyere;

In a device according to (r) hereinabove the closing movement is obtained by screwing the valve member in the nozzle, or through any other suitable means;

. In a device of the type set forth in paragraph (n), the base of the metal tube constituting each tuyere, which may be funnel-shaped as mentioned in paragraph (0), has formed in its outer face a communication leading to a leakage duct formed in the bottom plate of the converter so that in case of air leakage at the base of said funnel-shaped lower end the air under pressure is directed to the out side, instead of between the plate and the bottom, which would be particularly dangerous.

As will be readily understood, one. of the essential advantages characterizing this invention is that the airblast under pressure is kept and led under pressure by using tubular supply headers, whether toroidal or not, instead of causing this air to flow into a chamber of relatively great capacity, such as a conventional blowing box, the subdivision of the blast into as many streams as there are blowing orifices taking place at the initial ends of the supply header tubes. As a result, the air under pressure is constantly enclosed in tubes or pipes constituting the best possible type of container for keeping a gas under pressure.

Another advantageous feature of this invention lies in the fact that each blowing orifice can be connected and disconnected in an easy and quick way; in fact, the connection is obtained by using a special union of known type that fits instantaneously to the base of the copper tube lining the interior of the blowing orifice; conversely, when the union is disconnected from the tuyere tube the end of the flexible tube or pipe or of the small-diameter tube secured by its opposite end to the supply ring is closed automatically. Alternately, the connection and disconnection are responsive only to the simple actuation ofa valve member in a nozzle.

It is a further advantage of this invention that if, as a consequence of the blast pressure, and air leakage takes place at the base of the copper tube lining the relevant blowing orifice, any risk of causing this air to leak between the tube and the bottom plate is definitely precluded, thus eliminating a serious risk, notably of raising the converter bottom. In fact, the lower end of the copper tube is pressed with force against a tapered surface of the baseplate, and the space in which the leakage is likely to take place constantly communicates with the surrounding atmosphere.

Another advantageous feature characterizing this invention is that the access to the blowing orifices remains free, even without removing the supply headers. A general advantage of this invention also lies in the fact that leakages of blast air under pressure are nearly nonexistant and that if they occurred accidentally at any point they can be stopped immediately.

In order to afford a clearer understanding of this invention, two specific forms of embodiment thereof will now be described by way of example with reference to the accompanying drawings.

lneither case pure oxygen, under a pressure of about 13 to 14 bars to 205 p.s.i.), is supplied to a converter capable of refining 20 tons of pig iron. To this end, the bottom is provided with 162 blast holes lined internally with copper piping having an inner diameter of 3.5 mm. (about 0.14 inch).

These 162 blast holes are distributed into six concentric circles or rows having the following diameters and number of orifices:

1st row.dian1eter=400 mm. (15%) 12 holes 2nd row.diameter=625 mm. (24.6") 18 holes 3rd row.di:m1eter=850 mm. (33%) 24 holes 4th row.-din.meter=1,075 mm. (42%) 30 holes 5th row.diametcr= 1,300 mm. (51) 86 holes 6th row.diameter= 1,525 mm. (60) 42 holes FIRST FORM OF EMBODIMENT FIG. 1 illustrates in diagrammatic vertical axial section the set of supply headers consisting of copper piping.

FIG. 2 is a detail view showing in part-sectional, part elevational view and on a larger scale the connection of one of these headers to one of the blowing orifices.

FIG. 3 illustrates a general view of the six headers supplying the blast air, and the communication ducts associated therewith.

FIG. 4 is a vertical section showing the connection between the blast wind supply to the outermost header and one of the communication ducts, and

FIG. 5 is a vertical section showing a nozzle or injector with its valve member registering both with one of the tuyeres.

As illustrated in FIG. 1 the blast consisting basically of pure oxygen but in which other gases may be incorporated for producing either a safety effect or a stirring or cooling effect, is introduced into an inlet 1 comprising a union 2. One portion of this union 2 is connected to a first ring 3 of the device according to this invention. This main header 3 has a twofold purpose: on the one hand, supplying the blast to the 42 blowing holes of the sixth row, on the other hand, transmitting the gaseous flow to the

other headers

4, 5, 6, 7 and 8, as well as to a central balancing box 9, through the medium of two radial copper communication ducts 10 and l l.

The main header 3 has an inner diameter of 60 mm. and the diameter of the tore constituted by this header is 1.70 meter (67 inches). The radial communication ducts I0 and 11 have an inner diameter firstly of 50 mm. (2 inches), then of 40 mm. (1.57 inches). I-

Ieaders

4, 5, 6, 7 and 8 have each an inner diameter of 35 mm., and their tore diameters are respectively 1.4 m., 1.18 m., 0.97 m., 0.74 m. and 0.525 m.

The connection between a typical header and a blast hole is illustrated in FIG. 2.

A copper pipe 12 having an inner diameter of 6 mm. forming a complete turn to impart a certain flexibility thereto connects the header, for example the header 3, to the tube 13 of the blowing tuyere or like aperture considered in this specific case, of which the inner diameter is 3.5 mm. The spiral pipe 12 is connected to a first self-stopping union l4 and to the tube 13 by another self-stopping union 15. Each one of these unions comprises a male member and a female member; in the case of the first union 14, the female member is welded to the header 3 and the male member constitutes the end of the spiral-coiled tube 12; in the case of the second union 15, the female member is welded to the end of the spiral-coiled tube 12 and the male member is welded to the tube 13 of the blowing orifice. When the unions are connected and tightened the blast circulates without any leakage. If it is desired to check the condition of the blast tube 13, or to definitely bypass same, it is only necessary to disconnect the second union l5 and then the valve member contained in the female member closes immediately, thus avoiding any oxygen leakage from the header 3.

In case of oxygen leakage between the male member 16 of union and the base of tube 13, this leakage is discharged through the leakage duct 17 provided between member 16 and the bottom baseplate 18. Thus, oxygen cannot seep between the tube 13 and the bottom plate 18.

In the exceptional case of a spiral-coiled tube 12 becoming useless by fatigue strain in service or by accidental melting, or for any other reason, it is only necessary to disconnect the first Union 14 and thus the valve contained in the female portion which seal in a fluidtight manner the corresponding orifice of the collector, which can thus continue to supply the other blast holes still in service.

The set of supply headers 3 to 8 may be housed in a casing provided with a lid, in order to protect the headers and spiralcoiled tubes 12 against possible shocks or the projection of incandescent materials.

Of course, the spiral-coiled copper tubes may be replaced by flexible piping or any other device characterized jointly by a certain flexibility and by an adequate safety of operation, considering the blast pressure involved.

SECOND FORM OF EMBODIMENT The second from of embodiment described hereinabove with reference to FIGS. 3 to 5 of the drawing comprises six headers disposed each beneath one of the six rows of blast holes of the converter bottom.

The communication between the headers and the blast holes is obtained by means of one nozzle or injector per hole, each nozzle or injector being provided with a valve member.

FIG. 3 illustrates the six toroidal headers 21 to 26 corresponding to the six rows of blast holes. The header 21 corresponds to the peripheral row.

These headers are interconnected by four communication ducts 27 to 30 of which the cross-sectional passage area decreases towards the center, according to a law ensuring a uniform distribution of the blast through the complete set of I62 blast holes.

The blast wind under pressure is supplied to the device through the inlet 31.

FIG. 4 is a section taken along the line 343 and shows a detail of the ingress of blast gas into the device.

The blast inlet duct 3ll-is welded both to plate 32 supporting the dolomite bottom of the converter (not shown) and to the peripheral converter 31. The blast following the path shown by the arrow 33 penetrates both into the peripheral header 21 and into the communication duct 27. It penetrates through these two paths into the complete device consisting of the six headers and the four communication ducts.

FIG. 5 is a section taken along the line C-C of FIG. 3, i.e. along the axis of a blast tuyere, its nozzle or injector and its stop valve.

The bottom plate 32 supports the bottom 34 of the converter which consists of dolomite and tar, or any other suitable refractory material. Orifices such as 35 are formed therethrough to permit the passage of the copper pipes such as 36 constituting the metal portion of the tuyere. The base of the copper pipe is outflared and constitutes a kind offunnel 37 soldered to the bottom plate 32. Moreover, the semisphcrical head 43 of injector 42 is adapted to press the above-mentioned funnel-shaped end 37 against the baseplate 32, whereby a theoretically complete fluidtightness is obtained. Should one fraction of the blast under pressure seep accidentally to the outside of pipe 36, this gas would be discharged via the leakage duct 38 and would thus be prevented from attaining the underface of the dolomites, bypassing between the tube 36 and plate 32.

The header 21 is welded at 39 to the base plate 32.

At the location where the leakage duct 38 is machined the latter is closed by adding some solder 40.

The chamber 41 of header 21 contains the blast gas, for example under a pressure of 13 to 14 bars 190 to 205 p.s.i.).

The injector or nozzle 42 is a piece of revolution disposed coaxially to the copper tube 36 extending through the wall of header M in a perfectly fluidtight manner. The semisphcrical head 43 of nozzle 42 is formed with an axial-tapered bore 44 having substantially the shape of an inverted frustum of a cone. At its lower end this bore 44 is connected to a cylindrical bore 45 of a diameter at least equal to the inner diameter of tube 36. The nozzle 12 comprises a cylindrical inner cavity 436 in which the valve member 47 and a ball valve 48 are adapted to move axially. The blast position of valve member 47 is its lowermost position. The chamber under pressure 46 of the header communicates with the inner cavity 46 of the nozzle or injector through one or more orifices such as 49 machined in the nozzle wall. The bore 15 and tube 36 are thus supplied with blowing gas under pressure.

During the useful life of a converter bottom it may happen that the service life of one or more tuyeres is considerably shorter than that of the other tuyeres, and the at the worn tuyeres have to be put out of service. This is obtained by simply moving the valve member 47 upwards until the ball valve 48 engages the bottom edge of bore 45, thus cutting off any communication between the cavity as of the nozzle and the copper tube 36. Under these conditions the tuyere 36 is put out of service and its wear and tear are discontinued immediately. The closing movement may be obtained by screwing the valve member 437 in injector or nozzle 42, or through any other suitable means.

The fluidtightness between nozzle 42 and valve member 47 is obtained by disposing two rubber or like packings 50 therebetween.

in principle, the injector or nozzle 42 is not moved during the entire service life of the converter bottom. When this bottom is destroyed the nozzles or injectors are removed by maneuvering their heads 51.

Thus, the tuyere, its injector or nozzle and its valve member constitute an elongated unit of relatively small diameter and therefore of moderate overall dimensions, which can be used even in systems comprising tuyeres disposed at a relatively reduced spacing, as frequently observed in converters.

Of course, it would not constitute a departure from the spirit and scope of this invention to bring various modifications and variations in the practical embodiment of the device constituting the subject matter thereof, and even to contemplate the use of equivalent means.

What we claim is:

l. A device for supplying blast gas to the blowing orifices at the bottom of a steelwork converter comprising a plurality of header tubes having the shape of concentrically disposed tores, each header tube supplying blast gas to a plurality of bottom orifices, pipes or" small diameter connecting said supply header tubes to the blast orifices, said pipes being bent to form turns to impart flexibility for assembling and disassembling purposes.

2. A device as set forth in claim ll, wherein said pipes are provided at one end on the blast orifices side with self stopping unionsto close automatically when they are disconnected.

3. A device as set forth in claim 2, wherein said blast orifices are provided with copper tubes of small diameter which can be connected and disconnected by operating the end union of said pipes having said imparted flexibility.

4. A device as set forth in claim 2, wherein the assembly comprising each union, the lower end of the copper tube lining each blowing orifice and the baseplate of the converter bottom are arranged so that in case of accidental leakage of blast gas as a consequence of pressure between the union and the lower end of the copper tube, the leakage gas is vented to the surrounding atmosphere and safely prevented from seeping between the tube and the bottom plate.

5. A device for supplying blast gas to blowing orifices at the bottom of a steelwork converter comprising a plurality of header tubes having the shape of concentrically disposed tores; each header tube supplying blast gas to a plurality of fices for checking and service maintenance purposes, and also to facilitate disconnecting same in case of abnormal wear in relation to wear of other adjacent orifices.

Claims

1. A device for supplying blast gas to the blowing orifices at the bottom of a steelwork converter comprising a plurality of header tubes having the shape of concentrically disposed tores, each header tube supplying blast gas to a plurality of bottom orifices, pipes of small diameter coNnecting said supply header tubes to the blast orifices, said pipes being bent to form turns to impart flexibility for assembling and disassembling purposes.

2. A device as set forth in claim 1, wherein said pipes are provided at one end on the blast orifices side with self-stopping unions to close automatically when they are disconnected.

5. A device for supplying blast gas to blowing orifices at the bottom of a steelwork converter comprising a plurality of header tubes having the shape of concentrically disposed tores; each header tube supplying blast gas to a plurality of bottom orifices; said supply header tubes being connected to the blast orifices by means of flexible piping; said supply headers being disposed between two adjacently disposed rows of said bottom orifices in order to have free access to said orifices for checking and service maintenance purposes, and also to facilitate disconnecting same in case of abnormal wear in relation to wear of other adjacent orifices.