US3602435A - Blast device for steel converter - Google Patents

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.

Description

United States Patent [72] Inventors PierreL'eroy Appl. No. Filed Patented Priority 23, Rue de Tourville, St. Germain en Laye, 78;

Emile Sprunck, rue du Marechal Foch, Moyervre Grande, 57, both of, France 8,989

Feb. 5, 1970 Division of Ser. No. 739,553, June 24, 1968 Aug. 31, 1971 July 5, 1967,,Iune 17, 1968 France 113,156 and 155,193

BLAST DEVICE FOR STEEL CONVERTER 10 Claims, 3 Drawing Figs.

u.s.c| 239/551,

239/558, 239/562, 239/559, 266/41 1nt.Cl B05b1/14 FieldofSearch 239/550,

[561' References Cited I UNITED STATES PATENTS 685.230 10/1901 Speirs 239/2885 2,854,229 9/1958 Earle 266/41 2,977,108 3/1961 Cogelja et al. 266/41 X 3,116,143 12/1963 Reichl 266/41 X 3,210,043 10/1965 Burzlaff 251/320 Primary ExaminerMi Henson Wood, .Ir. Assistant Examiner-Thomas C. Culp, .lr. Attorney-Wenderoth, Lind & Ponack ABSTRACT: Device for supplying blast gas to the blowing orifrees 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.

- Pmmmusal Ian snmmrg INVENTORS PIERRE LEROY ATTORNEYS PATENTEU M1831 l97| SHEEI 2 m 2 %a v V as! INVENTORS RRE LEROY 47 LE SPRUNCK BLAST DEVICE FOR STEEL CONVERTER This application is a division of our application Ser. No. 739,553 filed June 24, 1968, entitled 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 psi,

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. Its lateral wall comprises one or more large apertures through which the air blast 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 ofa run.

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

However, if more recent steelmaking 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 of3 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 buyeres or blowing pipes, and therefore of suddenly causing the complete refractory bottom to blow up under the high air pressure.

c. If the blowing box diameter exceeds 2 meters-(6 feet 7 inch) the resultant of the pressure forces acting upon the bottom plate is very important. Thus, under a l2-bar (174 psi.) 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 p.s.i.

To this end the present invention provides a device for supplying an air 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 of one row.

This invention may also have one or more of the following features taken separately or in any combination:

a. The air blast header assembly is mechanically detachable as a unit;

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

c. The air blast 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;

e. The supply headers and the interconnecting ducts are made ofsteel;

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 small 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 at least one of their ends, on the blowing orifice side, or at either ends, with selfstopping 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; I

p. In a device of the type set forth in paragraphs (n) and (o) 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;

q. In a device of the type set forth in paragraphs (n), (o), (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;

r. In a device of the type set forth in paragraph (n), 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;

s. 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;

t. In a device of the type set forth above 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 outside, 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 air blast 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.

With the above and other objects in view, a preferred embodiment of the invention is shown in the drawings, in which:

FIG. 1 shows a general view of six headers supplying blast air and the communication ducts associated therein.

FIG. 2 is a vertical sectional view taken along Section Line 8-8 of FIG. 1, and

FIG. 3 is a vertical sectional view taken along Section Line CC of FIG. 1.

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 inches).

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

1st row: dia. dia. 400 mm. (15% inches) 12 holes 2nd row: dia. 625 mm. (24.6 inches) 18 holes 3rd row: dia. 850 mm. (33% inches) 24 holes 4th th row: dia. dia. 1,075 mm. (42%inches) 30 holes 5th row: dia. 1,300 mm. (51 inches) 36 holes 6th row: dia. 1,525 mm. (60 inches) 42 holes The embodiment described herein with reference to the Figures of the drawings 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. 1 illustrates a general view of the six headers supplying the blast air, and the communication ducts associated therewith.

FIG. 2 is a vertical section showing the connection between the blast wind supply to the outermost header and one of the communication ducts, and

FIG. 3 is a vertical section showing a nozzle or injector with its valve member registering both with one of the tuyeres.

FIG. 1 illustrates the six toroidal headers 21 to 26 corresponding to the six rows of blast holes. The header 21 correspond 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 162 blast holes.

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

FIG. 2 is a section taken along the line 8-8 of FIG. 1 and shows a detail of the ingress of blast gas into the device.

The blast inlet duct 31 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. 3 is a section taken along the line CC of FIG. 1, Le. 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 semispherical 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, by passing between the tube 36 and plate 32.

The header 21 is welded at 39 to the baseplate 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 2] 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 21 in a perfectly fluidtight manner. The semispherical head 43 of nozzle 42 is formed with an axial tappered 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 42 comprises a cylindrical inner cavity 46 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 lower most 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 45 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 that 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 46 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 47 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.

We claim:

l. A device for supplying blast gas to the blowing orifices at the bottom of a steelwork converter having a base plate comprising a plurality of header tubes, each header tube having a plurality of bottom orifices, means supplying blast gas to a row of bottom orifices, each of said header tubes welded to said baseplate engaging directly a row of blowing orifices and receives therethrough, in alignment with each orifice, a movable nozzle equipped with a valve member, the axes of said nozzle and said valve member being aligned with the axis of the relevant blowing orifice.

2. A device as set forth in claim 1, wherein each blowing orifice formed through the converter bottom consists of a metal tube, for example a copper tube, each tube having a funnelshaped lower end adapted to be soldered to the plate supporting the converter bottom, and said nozzle has a semispherical upper end adapted to engage in a fluidtight manner the inner wall of said funnel-shaped end by pressing same against said bottom plate.

3. A device as set forth in claim 1 wherein each hollow nozzle comprises, coaxially to its upper end, a cylindrical blowing orifice formed with an outflaring upper end to prevent the successive hammerings supported by the upper end of the nozzle from damaging the diameter of said cylindrical portion controlling the gas output.

4. A device as set forth in claim 2, wherein each hollow nozzle comprises, coaxially to its upper end, a cylindrical blowing orifice formed with an outflaring upper end to prevent the successive hammerings supported by the upper end of the nozzle from damaging the diameter of said cylindrical portion controlling thegas output.

5. A device as set forth in claim 1 wherein the inner cavity of the nozzle which supplies blast gas to said cylindrical orifice is adapted to communicate with the blast under pressure contained in the header through a number of ducts of which the total cross-sectional passage area is calculated with a view to avoid any limitation of the gas output.

6. A device as set forth in claim 2, wherein the inner cavity of the nozzle which supplies blast gas to said cylindrical orifices is adapted to communicate with the blast under pressure contained in the header through a number of ducts of which the total cross-sectional passage area is calculated with a view to avoid any limitation of the gas output.

7 A device as set forth in claim 3, wherein the inner cavity of said nozzle supplying said cylindrical orifice is adapted to communicate with the blast under pressure contained in said header by means of a number of ducts of which the total crosssectional passage area is calculated with a view to avoid any limitation of the gas output.

8. A device as set forth in claim 1, wherein the valve member of said nozzle consists of a solid member disposed inside said nozzle and provided with a ball valve at its top, said ball valve being adapted to engage the valve-sear forming lower edge of said cylindrical orifice of said nozzle as a consequence of the movement of said valve member when it is desired to put the corresponding tuyere out of service.

9. A device as set forth in claim 8, wherein said valve member movement is obtained by screwing same in said nozzle.

10. A device as set forth in claim 1, wherein the base of the metal tube constituting each tuyere, comprises on an outer face means permitting the communication with a leakage duct formed in the bottom plate of the converter whereby, in case of blast leakage at the base of said funnel-shaped base, the leakage under pressure is adapted to be vented to the outside instead of against said plate and the bottom of the converter.

Claims (9)

1. A device for supplying blast gas to the blowing orifices at the bottom of a steelwork converter having a base plate comprising a plurality of header tubes, each header tube having a plurality of bottom orifices, means supplying blast gas to a row of bottom orifices, each of said header tubes welded to said baseplate engaging directly a row of blowing orifices and receives therethrough, in alignment with each orifice, a movable nozzle equipped with a valve member, the axes of said nozzle and said valve member being aligned with the axis of the relevant blowing orifice.

2. A device as set forth in claim 1, wherein each blowing orifice formed through the converter bottom consists of a metal tube, for example a copper tube, each tube having a funnel-shaped lower end adapted to be soldered to the plate supporting the converter bottom, and said nozzle has a semispherical upper end adapted to engage in a fluidtight manner the inner wall of said funnel-shaped end by pressing same against said bottom plate.

3. A device as set forth in claim 1 wherein each hollow nozzle comprises, coaxially to its upper end, a cylindrical blowing orifice formed with an outflaring upper end to prevent the successive hammerings supported by the upper end of the nozzle from damaging the diameter of said cylindrical portion controlling the gas output.

4. A device as set forth in claim 2, wherein each hollow nozzle comprises, coaxially to its upper end, a cylindrical blowing orifice formed with an outflaring upper end to prevent the successive hammerings supported by the upper end of the nozzle from damaging the diameter of said cylindrical portion controlling the gas output.

5. A device as set forth in claim 1 wherein the inner cavity of the nozzle which supplies blast gas to said cylindrical orifice is adapted to communicate with the blast under pressure contained in the header through a number of ducts of which the total cross-sectional passage area is calculated with a view to avoid any limitation of the gas output.

6. A device as set forth in claim 2, wherein the inner cavity of the nozzle which supplies blast gas to said cylindrical orifices is adapted to communicate with the blast under pressure contained in the header through a number of ducts of which the total cross-sectional passage area is calculated with a view to avoid any limitation of the gas output. 7 A device as set forth in claim 3, wherein the inner cavity of said nozzle supplying said cylindrical orifice is adapted to communicate with the blast under pressure contained in said header by means of a number of ducts of which the total cross-sectional passage area is calculated with a view to avoid any limitation of the gas output.

8. A device as set forth in claim 1, wherein the valve member of said nozzle consists of a solid member disposed inside said nozzle and provided with a ball valve at its top, said ball valve being adapted to engage the valve-sear forming lower edge of said cylindrical orifice of said nozzle as a consequence of the movement of said valve member when it is desired to put the corresponding tuyere out of service.

9. A device as set forth in claim 8, wherein said valve member movement is obtained by screwing same in said nozzle.

10. A device as set forth in claim 1, wherein the base of the metal tube constituting each tuyere, comprises on an outer face means permitting the communication with a leakage duct formed in the bottom plate of the converter whereby, in case of blast leakage at the base of said funnel-shaped base, the leakage under pressure is adapted to be vented to the outside instead of against said plate and the bottom of the converter.

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