US3241825A

US3241825A - Blowing device

Info

Publication number: US3241825A
Application number: US210668A
Authority: US
Inventors: Jilek Walter; Truppe Meinhard
Original assignee: BOT Brassert Oxygen Technik AG
Current assignee: BOT Brassert Oxygen Technik AG
Priority date: 1961-07-21
Filing date: 1962-07-18
Publication date: 1966-03-22
Anticipated expiration: 1983-03-22
Also published as: DE1433418A1; FI41283C; FI41283B; AT236424B; GB1008723A

Description

March 22, 1963 W. JILEK [ET/AL BLOWING DEVICE Filed July 18, 1962 WALTER JILEK MEINHARD TRUPPE THEIR ATTORNEYS United States Patent 3,241,825 BLOWING DEVICE Walter .lilek and Meinhard Truppe, Linz, Austria, assignors to BOT Brassert Oxygen Technik AG., Zurich,

Switzerland, a company of Switzerland Filed July 18, 1962, Ser. No. 210,668 Claims priority, application Austria, July 21, 1961, A 5,620/61 3 Claims. (Cl. 26634) This invention relates to a blowing device for supplying the refining agent and the admixtures in carrying out metallurgical processes, e.g., in refining or pre-refining crude iron, in refining steel, in the preparation of alloys, and like processes in which the refining agent is supplied from above.

Blowing devices for use in surface-blowing processes are known which comprise a blast tube which conducts the refining gas and terminates in a convergent-divergent or de Laval nozzle. It has been proposed to introduce finely divided basic substances such as lime under pressure into the supply conduit of the blowing tube and supply them to the bath as a suspension in the refining gas. These known devices involved various disadvantages. High requirements regarding the purity and the structure of the admixtures had to be met. If the admixtures contained combustible impurities such as coal or iron particles, these impurities were ignited in contact with the oxygen and often caused a destruction of the hose lines. For this reason nickel-chromium steels had to be used as a material for the supply conduits, which rendered the equipment expensive. Besides, devices of this kind were subjected to considerable mechanical wear.

It has further been proposed to introduce admixtures such as finely divided lime through separate supply conduits into the expansion zone of the refining agent; in this case the admixtures were sucked in and mixed with the oxygen jet and carried into the zone of reaction of the oxygen jet. This method of working has the disadvantage that part of the energy of the oxygen jet is consumed for the suction effect so that the pressure of impact on the bath is reduced and sometimes becomes lower than is permissible for the desired performance of the refining process, If the nozzle blows too gently, slags having very high iron oxide contents are formed, which necessitates an after-treatment of the steel produced and results in iron losses.

It is an object of the invention to avoid these disadvantages and difiiculties. A special aim of the invention is to provide a blowing device which allows a controlled supply of the admixtures, without any risk of inflammation and without danger of an excessive wear of the constructive elements, while at the same time the adjustability of the oxygen jet, i.e. the possibility to selectively blow either with a sharp jet or with a gentle jet, is retained. The blowing device according to the invention is characterized in that the blast tube which terminates in a convergent-divergent nozzle is arranged in a concentric watercooled downcomer and adapted to be lifted and lowered therein, the annular space between the blast tube and the downcomer serving for the supply of admixtures. Conveniently the annular space communicates with a storage container for fine-grained or pulverulent admixtures, e.g. CaO, coke, ion ore and the like, which is under no pressure. As the supply is effected under no pressure, the abrasive action of the admixtures is slight, and the wear of the conduits insignificant.

According to a preferred embodiment of the invention the mouth portion of the blast tube is shaped to form a fitting part which can be inserted into the mouth portion of the downcomer in such manner that the downcomer is closed when the blast tube is in the lowered position. The

central blast tube may be adapted to be lifted and lowered by means of a spindle or any other suitable means. The fitting part of the blast tube and the seat part of the downcomer have a cylindrical or frustro-conical shape, the two parts corresponding to each other. From the seat of the downcomer upwards a frustro-conical portion may preferably adjoin, which passes into a cylindrical tube of larger diameter. By lifting and lowering the blast tube in the range of the conical portion a valve effect is produced, as the cross-sectional area of the annular space can be selectively increased or decreased.

The device according to the invention thus enables free control both of the quantity of the admixtures added and of the energy of the blowing jet. The cross section of the downcomer may be dimensioned for maximal supply rateswhen the central blast tube is in its topmost position; when the blast tube is in its lowest position, i.e. when the nozzle tip which forms the fitting part is inserted in the seat of the downcomer, the supply of admixtures is interrupted and the nozzle acts as a proper convergentdivergent nozzle.

The blowing device according to the invention is explained more fully in the accompanying drawing by way of exemplary embodiments.

FIG. 1 is a vertical sectional view of an embodiment having a conical fitting part and seat; FIG. 2 is a similar representation comprising a cylindrical fitting part and seat,

In FIG. 1 numeral 1 designates the blast tube which is arranged in a concentric downcomer and adapted to be lifted and lowered therein. 3 is the annular space between the blast tube and the downcomer. The mouth portion 4 of the blast tube has a convergent portion 5 and a divergent portion 6 and thus acts as a convergent-divergent or de Laval nozzle. Over the major portion of its length, i.e., as far as to 7, the blast tube confines a cylindrical cross section; the lower end of the mouth portion 8 is shaped to form a slightly conical fitting part which fits into the seat 9 provided at the lower end of the downcomer. As far as to 10 the downcomer has a cylindrical cross section. Between the seat 9 and the cylindrical portion, the conical part 11 is arranged. The downcomer 2 is a jacket tube, i.e. it consists of the actual inner tube 2 and the outer tube 12, which tubes are integrally connected at their lower ends. concentrically arranged in the jacket space is a guide tube 13 to provide for the circulation of a coolant. The lower end 14 of the guide tube is shaped to form a stream-lined guide body. 15 are spacers.

The embodiment shown in FIG. 2 differs from that according to FIG. 1 only in that the .blast tube 1 has a cylindrical fitting part 16 which Ms in a seat 17 of the downcomer which has likewise cylindrical shape. In this em.- hodiment the outer wall of the blast tube is cylindrical over its entire length.

The blowing devices illustrated in the drawing are op erated by lifting and lowering the central blast tube by means of a spindle or a similar suitable means. It is evident that the entire cross-sectional area of the annular space is available for conveying the admixtures, when the nozzle tip of the central blast tube is at position 10 or higher. When the blast tube is lowered from this highest position, the annular space is continually decreased until, when the fitting part engages in the seat, the supply of admixtures is finally interrupted. From this position downwards, the blowing device acts as a proper convergent-divergent nozzle. Owing to the solid construction of the mouth portion of the blast tube, damages are reliably avoided.

In the following examples experimental heats which were carried out with the blowing device according to the invention are illustrated in detail.

Example 1.Refining of steelmaking iron After formation of a charge from 5,820 kg. liquid crude iron having a composition of: 4.06% C, 0.73% Si, 2.09% Mn, 0.124% P, 0.048% S, and 550 kg. scrap and addition of 50 kg. scarfing scale, 40 kg. bauxite, and 40 kg. fiuorspar, a blowing device of the type illustrated in FIG. 1 was entered into the crucible. The central blast tube had an inside diameter above the throttle portion of 33 mm. and a nozzle diameter of 21 mm. The length of the convergent portion was 20 mm., and the length of the divergent portion 39 mm. The inside diameter of the downcomer above the conical portion was 67 mm. The blowing device was adjusted to a distance of 500 mm. above the bath surface, and blowing started at a pressure of 12 kp./cm. gauge. During a period of 20 minutes 450 kg. of line dust was supplied through the annular space. Then the supply of admixtures was interrupted by lowering the blast tube, and blowing continued for 7 minutes. Finally the blowing device was withdrawn, the crucible tilted and a steel sample taken which had the following composition: 0.06% C, Si, 0.45% Mn, 0-01 P, 0.015% S. The output was 5,600 kg.=88%.

Example 2.C0nversion of basic Bessemer iron and termination of the heat at a desired carbon content A charge of 6,000 kg. liquid crude iron assaying for 3.72% C, 0.35% Si, 0.40% Mn, 1.760% P. 0.033% S, to which 100 kg. bauxite and 50 kg. scarfing scale had been added was blown by means of a blowing device as illustrated in the drawing. The distance of the blowing device was 400 mm.; oxygen pressure 10 kg./cm. gauge.

During an initial period of 14 minutes 550 kg. lime and 60 kg. sand were added through the annular space of the blowing device. By lowering the blast tube into the seat of the downcomer the supply of admixtures was shut off and the oxygen supply then stopped. 20 kg. of iron ore was added in one batch, and during the following 2 minutes the bath was deslagged and a preliminary sample taken which had the following composition: 1.92% C, 0% Si, 0.25% Mn, 0.230% P, 0.020% S. Then 50 kg. bauxite and 40 kg. sand were added as new slag-forming agents, and blowing was continued for another 7 minutes, during which period 350 kg. of lime was added through the annular space of the device. Finally the blowing device was withdrawn and a steel sample taken which had the following composition: 0.40% C, 0% Si, 0.18% Mn, 0.020% P, 0.017% S. The output was 5,150 kg. of steel=85.7%.

Example 3.Carbarizing and heating of a melt A charge of 5500 kg. of steel having the following composition: 0.04% C, 0% Si, 0.35% Mn, 0.015% P, 0.017%

S, and a temperature of 1540 C. was to be carburized to 1% carbon and the temperature raised. The blowing device illustrated in the drawing was introduced into the crucible, the distance from the bath adjusted to 400 mm., and the oxygen pressure controlled to 5 kg./cm. gauge. During a period of 9 minutes normal m. of oxygen were blown and 220 kg. pitch coke meal supplied through the annular space of the blowing device. Blowing was terminated, the blowing device withdrawn, and a steel sample taken, which had the following composition: 1.02% C, 0% Si, 0.28% Mn, 0.018% P, 0.019% S. The temperature was 1580 C.

What we claim is:

1. A blowing device for supplying an oxygen-containing refining gas and admixtures in surface-blowing processes, comprising a blast tube terminating in a convergentdivergent nozzle and a downcomer concentrically surrounding the blast tube to provide for an annular space, said blast tube being adapted to be lifted and lowered within said downcomer, said blast tube serving for the supply of the refining gas and said annular space between said blast tube and said downcomer serving for the supply of admixtures in the lifted position of said blast tube, said downcomer including a downwardly and inwardly shaped port-ion adjacent the mouth portion of the downcomer adapted to direct the admixtures into the refining gas supplied from the nozzle of the blast tube, the mouth portion of the blast tube being shaped to form a fitting part adapted to be inserted into the mouth portion of the downcomer, which forms a seat part, the annular space being closed when the blast tube is in the lowered position.

2. A blowing device as set forth in claim 1, wherein the fitting part of the blast tube and the seat part of the downcomer are of cylindrical shape, the two parts being complementary to each other.

3. A blowing device as set forth in claim 1, wherein the fitting part of the blast tube and the seat part of the downcomer are of frustro-conical shape, the two parts sloping downwardly and inwardly and being complementary to each other.

References Cited by the Examiner UNITED STATES PATENTS 2,805,147 9/1957 Sch'reiber 26634 X 2,829,960 4/1958 Vogt 266-34 X 3,130,252 4/1964 Metz 266-35 J OHN F. CAMPBELL, Primary Examiner.

WINSTON A. DOUGLAS, JAMES H. TAYMA-N, JR.,

Examiners.

Claims

1. A BLOWING DEVICE FOR SUPPLYING AN OXYGEN-CONTAINING REFINING GAS AND ADMIXTURES IN SURFACE-BLOWING PROCESSES, COMPRISING A BLAST TUBE TERMINATING IN A CONVERGENTDIVERGENT NOZZLE AND A DOWNCOMER CONCENTRICALLY SURROUNDING THE BLAST TUBE TO PROVIDE FOR AN ANNULAR SPACE, SAID BLAST TUBE BEING ADAPTED TO BE LIFTED AND LOWERED WITHIN SAID DOWNCOMER, SAID BLAST TUBE SERVING FOR THE SUPPLY OF THE REFINING GAS AND SAID ANNULAR SPACE BETWEEN SAID BLAST TUBE AND SAID DOWNCOMER SERVING FOR THE SUPPLY OF ADMIXTURES IN THE LIFTED POSITION OF SAID BLAST TUBE, SAID DOWNCOMER INCLUDING A DOWNWARDLY AND INWARDLY SHAPED PORTION ADJACENT THE MOUTH PORTION OF THE DOWNCOMER ADAPTED TO DIRECT THE ADMIXTURES INTO THE REFINING GAS SUPPLIED FROM THE NOZZLE OF THE BLAST TUBE, THE MOUTH PORTION OF THE BLAST TUBE BEING SHAPED TO FORM A FITTING PART ADAPTED TO BE INSERTED INTO THE MOUTH PORTION OF THE DOWNCOMER, WHICH FORMS A SEAT PART, THE ANNULAR SPACE BEING CLOSED WHEN THE BLAST TUBE IS IN THE LOWERED POSITION.