US3811386A - Tuyere for introducing oxygen and a protective medium into converter vessels - Google Patents

Abstract

An improved system for supplying oxygen and a protective fluid to metal, below the surface of the metal, in refining vessels in which the tuyeres are connected separately to the supply of oxygen and the supply of protective fluid.

Description

United States Patent [191 Knuppel et a1.

[11] 3,811,386 51 May 21, 1974 TUYERE FOR INTRODUCING OXYGEN AND A PROTECTIVE MEDIUM INTO CONVERTER VESSELS [75] Inventors: Helmut Knuppel; Karl Brotzmann;

Hans Georg Fassbinder, all of Sulzbach Rosenberg, Germany [73] Assignee: Eisenwerke Gesellschaft Maxiniilianshutte m.b.II., Sulzbach Rosenberg, Germany [22] Filed: Dec. 8, 1972 [21] Appl. N0.: 313,377

[30] Foreign Application Priority Data Dec. 9, 1971 Germany 2160999 [52] US. Cl 110/1825, 122/66, 266/41, 277/110, 285/133 R [51] Int. Cl. F23i l/00 [58] Field of Search 110/1825; 266/41;

[56] References Cited UNITED STATES PATENTS 3,703,279 1 H1972 Saccomano et a1 266/41 2,410,912 11/1946 Wenk 3,076,642 2/1963 Dhenein.' 266/41 Primary Examiner--Kenneth W. Sprague Assistant Examiner-James C. Yeung Attorney, Agent, or Firm-Lawrence 1. Field [5 7] ABSTRACT An improved system for supplying oxygen and a protective fluid to metal, belowthe surface of the metal, in refining vessels in which the tuyeres are connected separately to the supply of oxygen and the supply of protective fluid. 1

7 Claims, 3 Drawing Figures FATENTEUMAY 21 1374 SHEEI 1 [IF 2 FATENTEBHAY 2 1 i914 SHEET 2 (IF 2 This invention relates to a tuyere for reliable introduction of oxidizing gases, and particularly oxygen, and a fluid, i.e., a liquid or gaseous protective medium surrounding the oxidizing gases, into a refining vessel, in which one or several tuyeres are mounted below the bath surface, for the purpose of refining metals, preferably pig iron, contained in said vessels.

Most recently a process has been carried into practice, whereby pig iron is refined by blowing-in refining oxygen below the bath surface, together with a liquid or gaseous protective medium of a converter. This process is described in the German Auslegeschrift Pat. No. 1,583,968, British Specification Pat. No. 1,253,581 and in U.S. Pat. No. 3,706,549 issued December 19, 1972. The tuyeres for the refining gas and for the protective medium consist essentially of two concentric tubes. The refining gas, preferably oxygen, is passed into the vessel through the inner tube, while the liquid vor gaseous protective medium is passed into the vessel through the annular space between the two concentrically mounted tubes. The annular space separation is approximately 1 mm and is maintained by spacers between the two tubes, for instance by inner ribs on the outer tubes. Preferably liquid or gaseous hydrocarbons, more particularly light fuel-oil, propane or natural gas, are used as protective media for the oxygen jet so as to reduce tuyere burn-off and wear of the refractorymasonry. The concentric arrangement of the tuyere tubes passing through the refractory masonry into the refining vessel and terminating below the bath surface is achieved in fairly simple manner by 'using spacers between the inner and outer tubes. A number of procedures for making spacers are known. Thus the spacers may consist of coils brazed or welded on the-inner tube, or they may be outer ribs on the inner tube or inner ribs on the outer tube, or evenly distributed point-like elevations on either tube.

Whereas this part of the tuyeres may be so fashioned with simple means as to be functionally and operationally reliable, supplying both tuyere ducts with different gases raises appreciable difficulties. Constructional solutions for supplying-two different gases to tuyeres consisting of concentric tubes are known. For instance, the German Offenlegungsschrift Pat. No. 2,003,339 describes a device for feeding the blowing tuyeres of a steel converter. The known construction however suffers from several appreciable drawbacks in practice.

. Supplying the two gases is effected by a consolidated supply system sub-divided into two chambers. This solution may lead to the undesirable mixing of the two gases in case of leaks. In particular, introducing a combustible protective medium through the annular space and oxygen through the refining gas tube may lead to dangerous fires and to explosions if there is a leak in the supply system. Also, sealing means made of organic and elastic materials such as rubber have been found unsuitable for usual converter operations, because impurities may damage the seals and because they are'insufficiently temperature resistant.

To provide a tuyere for operationally reliable introduction of a refining gas together with a protective medium into a converter, the present invention proceeds from the consideration that high technical requirements together with easy handling under rough steelmaking operations must be met with .respect to feeding the two fluids to the tuyeres made of two concentric a. the inner tuyere tube should be easily removable and interchangeable for the purpose of monitoring its remaining length;

b. lek the fluids must be excluded in case of a leak in the supply system of either fluid;

c. any seals utilized must be operational at least up to temperatures of 300 C and may not consist of soft, organic materials.

The improved device of the present invention consists of a tuyere in which an oxygen-containing gas flows through the inner duct and the hydrocarbo-' naceous medium flows through the outer duct, and wherein the two media for the inner and outer ducts are so supplied as to'be spatially isolated from one another and the seals are fundamentally only in contact with ambient, so that sealing of both media with respect to each other is avoided. Sealing is achieved by metallic components such as conical and wedge rings and the like which are not susceptible to the temperature instability of rubber and other organic seals.

The particularities of the device according to the invention which achieve reliable operation of the refining gas tuyeres with protective media will be better understood from the description which follows taken with the drawings in which: 7

FIG. 1 is a longitudinal section through a tuyere con sisting of two concentric tubes in which the refining gas and the protective medium are supplied according to the invention;

HO. 2 is a cross-section through the dual concentric tube tuyere of FIG. I; and

FIG. 3 is a longitudinal section similar to FIG. 1 showing the connections of both tuyere ducts to their supply lines.

The tuyere for the refining gas and for one protective medium consists of two concentric tubes 1 and 2. The outer tube 1 may be made of any suitable material such as ordinary steel, copper or high grade steel. The outer tube 1 is provided with inner l8 3 which serve as spacers for the inner tube 2. Outer tube 1 is inserted into the inner converter space through a bore hole'4 in the converter jacket 5 and further passes through refractory masonry 6. As an example, steel member 5 may be 34 converter bottom plate and tube 1 may be pressed into the refractory bottom lining. A welded flange 7 serves as a stop for outer tube 1 and for securing it to the steel plates. In addition, outer tube 1 may be rigidly connected by such fasteners as bolts to the steel plate 5 of the refining vessel. The outer tuyere tube 1 terminates outside the steel jacket directly below a seal 9.

In lieu of the usual fastening and sealing means between flange 7 and steel plate 5, a particularly simple and temperature resistant seal between outer tube l .and bore hole 4 in the'steel plate 5 has been. found to very effective. Good results have been achieved by using a ceramic putty preferably .a substance from the v SiO -AI Q, system that has been mixed with water-glass and/or phosphoric acid solutions or with cement addi-- tion and water. Putty layer 8 serves as fastening and sealing means and is located between outer tube 1, and steel plate 5 up to flange 7. Besides being simple to inand cleaning following each converter campaign, as regards the tuyere ducts. I

The inner tuyere tube 2, provided for passage of the refining gas into the converter and below bath surface, is inserted into the outer tuyere tube 1 which is provided with inner ribs. One particularly preferred inner tuyere tube material is a high-grade stainless steel with 18 percent Cr and percent Ni. However, other metals such as copper or steels differently alloyed may be used. In one installation, the dimensions of the tuyere tubes was as follows: 1

OUTER TUBE 1, OD 28 mm, ID 24 mm, maximum rib height 1 mm; INNER TUBE 2, OD 22 mm, ID 18 mm.'As shown, inner tube 2 is longer than outer tube 1, because,'although both tuyere tubes terminate at the converter inner side, inner tube 2 extends beyond outer tube 1 at the converter outer side. A suitable difference in length is 150 mm in the installation shown. I

The annular space subtended between outer tube 1 and inner tube 2 must be sealed against the outsides of both gas supply tubes. A sleeve 10 is brazed or welded to inner tube 2. A clamping nut ll together with metallic sealing ring 9, which may be a wedge, double wedge or'conical sealing ring or the like, seals outer tube 1 with respect to the ring space 12. Feed tube 14 for the liquid or gaseous protective medium is welded into the bolting connector 13. Corresponding to the clamping nut 11 and sealing ring 9 of the outer tube, clamping nut 15 and sealing ring 16 seal off inner tube 2 with respect to the ring space 12. The lengths of the bolting connector 13 and of sleeve 10, which is brazed on the inner tube, thereby determine the shifting latitude of the inner tube in the longitudinal direction. In the present installation the shifting latitude amounts to about 25 mm.

A threaded joint between refining gas supply line 17 and inner tube 2 is located below the protective medium supply line and the sealing elements of the latter. Clamping nut 18 together with the metallic sealing ring 19 serve as a seal of the refining gas feed line with respect to the inner tube. Because of the separation of the protective medium and refining gas sealing elements, there can be no undesirable mixing of these media in case of leaks, since individually they aresealed only with respect to the ambient atmosphere and not with respect to each other. The spacing between the two feed lines is only determined by the extension in length of the inner tube. Theoretically, the latter length may be selected at will, but there are limits on mechanical grounds; in the converter shown, the clear spacing 20 between the sealing elements amounts to about 150 mm. Suitable fittings are provided between the gas or protective medium supply to the corresponding tuyere ducts and its connection to the associated supply lines, which serve to compensate dimensional inaccuracies when fitting the tuyere feed lines to the supply lines. In order to connect the ring space 12 with the protective medium supply line 21, ordinarily straight and angular connecting pieces, and the displacement possibilities provided by these, will suffice in view of the relatively thin conduit for feeding the liquid or gaseous protective medium. All the sealing means for this tuyere feed line for the protective medium are metallic wedge, cone and/or double wedge rings and the like. Various regulatory means 22 are installed in the tuyere feed line. These include, for instance, back-pressure valves, throttle restrictors for metering the protective medium and/or controllable switch-over and switch-off valves. Said regulating means may be installed and several may be arranged in parallel and/or in series. Installation is efiected using mechanical sealing rings and straight and angular connecting pieces. In the installation shown in FIG. 3, the line segment 14 between the supply line 21 and the protective medium feed-in, is approximately 10 mm. Tube 14 is of copper or steel.

The tuyere feed line for the refining gas could be connected to the supply line in the same manner as the protective medium line. Thus, for a tuyere of fairly small diameter, as may be the case for a refining gas feed line, the outer diameter of which is less than 15 mm, the connecting pipe between the refining gas feed-in and the supply line is preferably U-shape and is connected using metallic sealing rings and fittings or connectors. As the tube diameter increases, that is, for larger tuyeres, this arrangement no longer affords sufficient fitting clearance'when assembling, In such cases, that is, for diameters exceeding 20 mm, the construction shown in FIG. 3 was found to be preferable. Anglepiece 23 is brazed or welded to tuyere inner tube 2, located to provide the desired safetyspacing 20 between the protective medium feed-in and angle-piece 23. This angle-piece 23 is provided with a maintenance-fitting 24 in an inner tube extension. Normally, the maintenance-fitting 24 will be blank-flanged and opened only for maintenance, for instance for measuring tuyere length or if necessary, for padding the inner tube with, say, a ceramic substance if the tuyere-were to break down.

The angle piece 23 is connected by means of a threaded fitting 25 and a metallic ring seal 26 to another angle-piece 27. Threaded fitting 25 is so designed that it allows a shift latitude'of about 25 mm in the tube seal. A tube segment of any suitable length may be welded-in between threaded fitting 25 and the angle piece 27. Angle-piece 27 is connected via 'a ball-andsocket joint 28 to the refining gas supply line 29. Balland-socket joint 28 permits rotation in any direction. Because of the feasibility of shifting provided in threaded fittings 15 and 25 and on account of ball-andsocket joint 28, any dimensional inaccuracies may be easily accommodated when fitting the supply lines to the tuyeres. The OD of the tuyere feed line in the example shown may be 25 mm for the refining gas. The feed line is made from ordinary steel tubing, though othermetal tubes may also be used, such as copper tubes or alloyed steel tubes.

The tuyere according to the invention and designed for the reliable introduction of refining gas together with a protective medium besides simple and reliable construction also is highly economical. It has been found in operation that elastic lines or springs or similar elastic connecting means are not required. The elimation of sensitive, elastic connecting pieces especially in the rough steel-making operations and elimination of the dangers of possible leaks in the feed lines represents an appreciable technical progress.

We claim: 7

1. In a combination with a tuyere passing through the steel mantle and the refractory masonry of a convertor,

for reliably feeding oxidizing refining gases surrounded by a liquid or gaseous protective medium into a molten metal bath, said tuyere being disposed to discharge said fluids underneath the metal bath level, the refining gas being supplied to said molten metal through an inner tuyere pipe and the protective medium being supplied through an annular space between the inner tuyere pipe and an outer, coaxial pipe, said outer pipe leading to a supply cap or head surrounding a sleeve of the inner through-pipe and a closure for the outer tuyere pipe; the improvements which comprise:

providing separate connections between said supply cap (13) and said inner tuyere pipe (2) and spatially separate supply sources (21, 29) respectively, for the protective medium and the refining gas, means hermetically sealing said sleeve peripherally with the inner tuyere pipe (2) by welding or soldering, metallic sealing rings located axially on both sides of said supply cap for sealing said supply cap with respect to the outer typere pipe (1) and with respect to the sleeve (10), and means for axially tensioning said metallic sealing rings on both sides. 2. A tuyere as defined in claim 1 including in addition clamping nuts or screw caps (1, 15) mounted on the supply cap (l3) for tensioning the sealing rings (9,16), said sealing rings being detachable.

3. A tuyere as defined in claim 1 wherein the extremities of sleeve (10) and of the outer tuyere pipe (1) are axially separated from each other and a longitudinally adjustable annular space (12) is formed between them.

4. A tuyere as defined in claim 1 including, in addition a putty seal or mastic seal between the outer surface of the outer tuyere pipe (1) and steel mantle (5).

5. In the tuyere as defined in claim 1, the metallic sealing rings (9, l6) and the putty or mastic (8) are each temperature resistant up to 300 C.

6. A tuyere as defined in claim 4 wherein the putty or mastic consists principally of SiO -Al O which is prepared from water glass and/or phosphoric acid solutions or with additions of cement and water.

7. A tuyere as defined in claim 1 including in addition ball joint connections (28) mounted in the supply lines (17, 27, 14) to the outer tuyere pipe (1) and to the supply cap (13).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, ,3 6 Dated May 21, 197

Inv )Helmut KnuDDel: Karl Brotzmann; Hans Georg Fassbinder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Correct assignee to--Eisenwerk-Gesellsshaft Maximilianshutte Column 2, line 10; change "lek' to--mixin;;--

Column 2, line '5; change "18" to -ribs Column 2, line 49; change "3 4" to--the- Column 6, line 12-; delete "ll" Signed and sealed this 5th day of November 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents -'ORM PO-1OSO (10-69) USCOMM-DC 60376-P69 a u4sv GOVERNMENT PRINTING OFFICE: l9" O--368-334

Claims (7)

1. In a combination with a tuyere passing through the steel mantle and the refractory masonry of a convertor, for reliably feeding oxidizing refining gases surrounded by a liquid or gaseous protective medium into a molten metal bath, said tuyere being disposed to discharge said fluids underneath the metal bath level, the refining gas being supplied to said molten metal through an inner tuyere pipe and the protective medium being supplied through an annular space between the inner tuyere pipe and an outer, coaxial pipe, said outer pipe leading to a supply cap or head surrounding a sleeve of the inner through-pipe and a closure for the outer tuyere pipe; the improvements which comprise: providing separate connections between said supply cap (13) and said inner tuyere pipe (2) and spatially separate supply sources (21, 29) respectively, for the protective medium and the refining gas, means hermetically sealing said sleeve (10) peripherally with the inner tuyere pipe (2) by welding or soldering, metallic sealing rings located axially on both sides of said supply cap for sealing said supply cap wIth respect to the outer typere pipe (1) and with respect to the sleeve (10), and means for axially tensioning said metallic sealing rings on both sides.

2. A tuyere as defined in claim 1 including in addition clamping nuts or screw caps (1, 15) mounted on the supply cap (13) for tensioning the sealing rings (9,16), said sealing rings being detachable.

3. A tuyere as defined in claim 1 wherein the extremities of sleeve (10) and of the outer tuyere pipe (1) are axially separated from each other and a longitudinally adjustable annular space (12) is formed between them.

4. A tuyere as defined in claim 1 including, in addition a putty seal or mastic seal between the outer surface of the outer tuyere pipe (1) and steel mantle (5). 11

5. In the tuyere as defined in claim 1, the metallic sealing rings (9, 16) and the putty or mastic (8) are each temperature resistant up to 300* C.

6. A tuyere as defined in claim 4 wherein the putty or mastic consists principally of SiO2-Al2O3, which is prepared from water glass and/or phosphoric acid solutions or with additions of cement and water.

7. A tuyere as defined in claim 1 including in addition ball joint connections (28) mounted in the supply lines (17, 27, 14) to the outer tuyere pipe (1) and to the supply cap (13).

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