US3281136A

US3281136A - Method and apparatus for the gas injection into a metal bath

Info

Publication number: US3281136A
Application number: US134071A
Authority: US
Inventors: Metz Paul
Original assignee: Arbed SA
Current assignee: Arcelor Luxembourg SA
Priority date: 1960-09-12
Filing date: 1961-08-25
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25
Also published as: LU39169A1; DE1408783A1

Description

Oct. 25, 1966 P. METZ METHOD AND APPARATUS FOR THE GAS INJECTION INTO A METAL BATH Filed Aug. 25. 1961 INVENTOR fazx/Zfleiz BY mm 7 M United States Patent 3,281,136 METHOD AND APPARATUS FOR THE GAS INJECTION INTO A METAL BATH Paul Metz, Dudelauge, Luxembourg, assignor to LARBED, Acieries Reuuies de Burbach-Eich-Dudelauge, Society Anonyme, Luxembourg Filed Aug. 25, 1961, Ser. No. 134,071 Claims priority, application Luxembourg, Sept. 12, 1960, 39,169 1 Claim. (Cl. 266-34) The present invention relates to a process and an apparatus for the gas injection into a metal bath.

In the processes using injection from the top, in a metal bath by means of a lance, of a jet of oxidizing gas which may carry in suspension powdered or granulated solid materials, it is proposed when it is desired to cause the spreading out of the jet issuing from the lance to disturb the flow by injecting into the principal gas jet near the nose of the lance, some peripheric secondary jets of gas converging towards the axes of the tuyere.

In certain arrangements the injection lance comprises two concentric conduits, the inner conduit feeding the principal jet constituted for example by oxygen carrying in suspension pulverized lime while the outer conduit feeds the secondary jets of gas which may be different from the gas constituting the principal jet. This arrangement permits establishing or interrupting at will the secondary jets during the flow of the principal jet. There are processes for example, in refining in the Martin furnace where it is suitable to reduce in a permanent manner the penetration of the principal jet in the metal bath. In fact, in furnaces provided with an arch such as a vaulted roof, as are the Martin furnaces, the insufiiation in the bath of very penetrating gaseous jets causes strong projections which reach the arch where they attack violently.

According to the present invention these strong and violent projections are avoided by rendering the jet slightly penetrating during the entire duration of the blast, this result being obtained by disturbing its flow by means of secondary jets.

Certain arrangements permit the realization of this objective by means of permanent maintenance of the feeding of the secondary jets.

However, the same effect can be obtained with the aid of a lance of more simple construction which constitutes a second object of the present invention. The lance, object of the invention, comprises a single conduit for admitting gas or the insufilated mixture and is characterized in that the principal gas jet and the secondary jets serving to disturb the flow are both fed by the single conduit. To that end, the single conduit admitting gas or the insufilated mixture is provided at its open end with a convergent-divergent outlet tube or tuyere in the form of a spool or drum, engaged in the said conduit and which provides, between its own outer surface and the internal surface of the conduit, an annular chamber which is placed in communication by a group of cylindrical orifices or preferably divergent conical orifices with the outlet of the divergent part of the tuyere, on the one hand, and by another group of cylindrical or preferably convergent or convergent-divergent channels with the outlet tube of the divergent part of the tuyere on the other 3,281,136 Patented Oct. 25, 1966 hand. By this arrangement the annular chamber is fed with gas taken from the central jet in the convergent zone of the outlet tube and there is established in the said chamber a pressure greater than the pressure prevailing below in the divergent part. Because of this fact, the gas contained in the annular chamber flows through channels debouching in the divergent part of the outlet tube forming secondary jets with high speed which disturb the principal jet and consequently reduce the faculty of penetration in the metal bath of the resultant jet.

The axes of the secondary jets can meet at one and the same point of the geometric axis of the outlet tube or, on the contrary, can be oriented tangentially to an axial geometric nucleus in such a way as to impart a principal gyratory motion.

According to the invention it is advantageous to dimension the orifices and the channels of the outlet tube in such a way that the entire flow of the secondary jets will be not less than 20% of the total.

It is clear that the gas insufllated by the lance may or may not be admixed with pulverulent materials, as for example, lime.

By way of a non-restrictive example, the accompanying drawing shows as a vertical section an injection lance cooled by water circulation in accordance with the invention.

In the drawing, 1 designates the single conduit admitting the gas to be insufllated and Which contingently may carry pulverulent materials in suspension. 2 designates the outlet tube or tuyere comprising a convergent part 3 at one end and a divergent part 4 at the other end. 5 designates the chamber or space between the inner surface of the conduit 1, and 6 designates the orifice-s pierced near the entrance section of the convergent part 3 of the outlet tube 1. 7 designates channels pierced in the wall of the outlet tube near the outgoing section of the divergent part 4.

The axes of the channels 7 are disposed obliquely with respect to the axis of the tuyere, and their axes may or may not intersect the axis of the tuyere.

Owing to the convergent-divergent form of the central conduit of the outlet tube the pressure of the gas at the level A is greater than the gaseous pressure at the level B.

The total area of the orifices 6 being greater than the total area of the channels 7, the pressure established in the annular chamber 5 will be substantially equal to the pressure prevailing at the level A in the outlet tuyere 2. It follows that the pressure at the entrance of the channels 7 is about the same as the pressure prevailing at the level A, while at the outlet of the channels there prevails the pressure of the central jet at the level B which is, as stated, distinctly lower than the gaseous pressure at level A.

Consequently the secondary jets which flow through the channels 7 into the central or principal jet of the outlet tube are endowed with a great speed which renders them capable of effectively disturbing the said central jet, that is to say, to disperse the gases and/or the particles leaving the orifice of the outlet tube making them deviate in divergent directions.

I claim:

A device for injecting an oxidizing gas into a metal bath comprising a conduit feeding gas at its open end provided with a convergent-divergent tuyere engaged in the said conduit and which provides between its own external surface and the internal surface of the tuyere an annular chamber which is in communication by a group of orifices of conical and divergent configuration with the upper part of the convergent of the tuyere and convergent-divergent channel-s in the tuyere with the lower part of the divergence of the tuyere, said channels being oriented obliquely and convergently with respect to the axis of the tuyere.

References Cited by the Examiner UNITED STATES PATENTS Lataste 239 s43 x 15 3,130,252 4/1964 Metz 26635 FOREIGN PATENTS 962,937 12/ 1949 France. 685,715 12/1939 Germany.

3,449 1877 Great Britain. 254,603 7/ 1926 Great Britain. 667,654 3 195 2 Great Britain.

CHARLIE T. MOON, Primary Examiner.

WINSTON A. DOUGLAS, Examiner.

I. C. HOLMAN, B. E. LAKE, P. M. COHEN,

Assistant Examiners.