Method and device for supplying energy into a scrap metal pile in an electric arc furnace

Abstract

A method for supplying energy to a scrap metal pile (9) in an electric arc furnace (2). Energy is supplied by jets of hot gas in a first phase. Energy is supplied by electric arcs in a second phase after the first phase is completed. Hot gas is supplied via at least six jets. A device (1) for the method has an electric arc furnace (2), one or more blowing devices (6a, 6b, 6c), supply jets of reactant hot air into the chamber (7) of the electric arc furnace (8). The devices have a total of at least six nozzles (10a, 10b, 10c, 10d, 10e, 10f) with nozzle openings. Fuel conducting devices (8) supply fuel to the jets of reactant hot air.

Claims

1. A method for supplying energy into a scrap metal pile in an electric arc furnace that includes a cover wall having a center and a plurality of blowing apparatuses, each blowing apparatus being arranged in a respective opening in the cover wall, and each opening in the cover wall being spaced from the other openings in the cover wall and spaced from the center of the cover wall, the method comprising: in a first phase, supplying energy by a plurality of jets of hot gas into the furnace from the plurality of blowing apparatuses, the energy supplied by the plurality of jets being divided among the plurality of jets, and no jet supplying energy into the furnace supplies more energy than the energy supplied by the plurality of jets divided by the number of the plurality of jets that supply energy into the furnace; after completing the first phase, a second phase, supplying energy in the furnace by electric arcs in the furnace; the hot gas being supplied in at least six jets, each of the six jets supplies a maximum of a sixth of the overall quantity of hot gas supplied; wherein approximately 40 to 60% of the energy supplied to the scrap metal pile is supplied by means of the hot gas, and the remainder of approximately 60 to 40% is supplied by electric arcs in the furnace; wherein each blowing apparatus includes two spaced nozzles and a fuel apparatus adjacent each nozzle; and wherein each jet of hot gas is produced by reacting fuel from a fuel apparatus and a jet of reactant hot gas from a nozzle adjacent the fuel apparatus.

2. The method as claimed in claim 1, further comprising supplying the jets of reactant hot air from at least one blowing apparatus, wherein the jets are oriented so that the distance between the jets of the reactant hot air upon exiting the blowing apparatus is at least twice a diameter of the jets of the reactant hot air upon the reactant hot air exiting.

3. The method as claimed in claim 1, further comprising supplying the jets with the hot air from at least one blowing apparatus wherein a distance between the jets of hot gas in the scrap metal pile is at least five times a diameter of the jets of the reactant hot air upon the hot air exiting the blowing apparatus.

4. The method as claimed in claim 1, further comprising: in a first phase, supplying energy using jets of hot gas; in a subsequent second phase, discontinuing the jets of hot gas and then supplying energy using the electric arcs; and further comprising: generating the electric arcs with a respective operating area of each arc; and aligning at least one of the jets of hot gas toward zones of the scrap metal pile that are outside the operating area of each electric arc.

5. The method as claimed in claim 4, wherein the jets of hot gas that are aligned toward the zones of the scrap metal pile and are outside of the operating area of the electric arc each conveys a maximum of a twelfth of the overall quantity of hot gas supplied.

6. An apparatus, the apparatus comprising: an electric arc furnace having a base and side walls defining an interior of the electric arc furnace, and a cover wall located above the interior of the electric arc furnace, the cover wall having a center and a plurality of openings spaced from the center and spaced from one another; a plurality of blowing apparatuses, each configured for supplying a let of reactant hot air into the interior of the electric arc furnace and each blowing apparatus being in a respective opening in the cover wall, the blowing apparatuses overall having at least six nozzles each with a respective nozzle opening, each blowing apparatus having at least one of the at least six nozzles; and a plurality of fuel supply apparatuses each positioned adjacent a respective nozzle to supply fuel to the let of the reactant hot air from the nozzle; and wherein the distance between the nozzles is at least twice a diameter of the nozzle openings of the nozzles.

7. The apparatus as claimed in claim 6, further comprising all nozzles are the same.

8. The apparatus as claimed in claim 6, further comprising the blowing apparatus also includes the nozzles having the nozzle openings in the cover wall of the electric arc furnace.

9. The apparatus as claimed in claim 6, wherein the plurality of nozzle heads arranged in openings in the cover wall of the electric arc furnace that are provided for the introduction of electrodes.

10. The apparatus as claimed in claim 6, further comprising the nozzle openings of all of the nozzles have the same diameter.

11. The apparatus as claimed in claim 6, further comprising at least three separate ones of the nozzle heads and at least two of the nozzle openings are present in each of the nozzle heads.

12. A method for supplying energy into a scrap metal pile in an electric arc furnace, that includes a cover wall having a center and a plurality of blowing apparatuses, each blowing apparatus being arranged in a respective opening in the cover wall, and each opening in the cover wall being spaced from the other openings in the cover wall and spaced from the center of the cover wall, the method comprising: producing a plurality of jets of hot gas, each jet of hot gas being produced by reacting fuel from a fuel apparatus with a jet of reactant hot air from a nozzle located adjacent the fuel apparatus; in a first phase, supplying energy by the plurality of jets of hot gas into the furnace, after completing the first phase, in a second phase, supplying energy in the furnace by electric arcs in the furnace; wherein each of the plurality of jets supplies a respective fraction of the overall quantity of hot gas supplied, the energy supplied by the jets being divided among the jets, and no jet supplying energy into the furnace supplies more energy than the energy supplied by the jets divided by the number of jets that supply energy into the furnace; and wherein approximately 40 to 60% of the energy supplied to the scrap metal pile is supplied by means of the hot gas, and the remainder of approximately 60 to 40% is supplied by electric arcs in the furnace.

13. The method as claimed in claim 12, further comprising supplying the jets of reactant hot air from at least one blowing apparatus, wherein the jets are oriented so that the distance between the jets of the reactant hot air upon exiting the blowing apparatus is at least twice a diameter of the jets of the reactant hot air upon the reactant hot air exiting.

14. The method as claimed in claim 12, further comprising supplying the jets with the hot air from at least one blowing apparatus, wherein a distance between the jets of hot gas in the scrap metal pile is at least five times a diameter of the jets of the reactant hot air upon the hot air exiting the blowing apparatus.

15. The method as claimed in claim 12, further comprising: in a first phase, supplying energy using jets of hot gas; in a subsequent second phase, discontinuing the jets of hot gas and then supplying energy using the electric arcs; and further comprising: generating the electric arcs with a respective operating area of each arc; and aligning at least one of the jets of hot gas toward zones of the scrap metal pile that are outside the operating area of each electric arc.

16. The method as claimed in claim 15, wherein the jets of hot gas that are aligned toward the zones of the scrap metal pile and are outside of the operating area of the electric arc.

17. An apparatus, the apparatus comprising: an electric arc furnace having a base and side walls defining an interior of the electric arc furnace, and a cover wall located above the interior of the electric arc furnace, the cover wall having a center and a plurality of spaced openings spaced from one another and the center; a plurality of blowing apparatuses each configured for supplying a jet of reactant hot air into the interior of the electric arc furnace and each received in a respective opening in the cover wall, each blowing apparatus comprising a nozzle head, and at least one nozzle; and a plurality of fuel supply apparatuses each positioned to supply fuel to a respective jet of the reactant hot air supplied from a respective nozzle.

18. The apparatus as claimed in claim 17, further comprising the distance between the nozzles is at least twice a diameter of the nozzle openings of the nozzles.

19. The apparatus as claimed in claim 17, further comprising the blowing apparatus also includes the nozzles having the nozzle openings in the cover wall of the electric arc furnace.

20. The apparatus as claimed in claim 17, wherein the plurality of nozzle heads arranged in openings in the cover wall of the electric arc furnace that are provided for the introduction of electrodes.

21. The apparatus as claimed in claim 17, further comprising the nozzle openings of all of the nozzles have the same diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic representation of an example of an inventive apparatus, which is suited to implementing an inventive method, showing an electric arc furnace in a side cross-section of view.

(2) FIG. 2 shows the electric arc furnace of FIG. 1 in a top view.

DESCRIPTION OF EMBODIMENTS

(3) FIG. 1 shows a schematic and exemplary inventive apparatus 1 which is suited to implementing an inventive method, with an electric arc furnace 2 viewed from the side in cross-section. The electric arc furnace 2 has a base 3, side walls 4 and a cover wall 5. The inventive apparatus 1 also includes a number of blowing apparatus 6a, 6b, 6c for supplying reactant hot air into the interior 7 of the electric arc 2. Fuel supply apparatus 8 supply fuel to the jets of reactant hot air emerging from the blowing apparatuses 6a, 6b, 6c, in this case the fuel is natural gas. The exothermic reaction of the fuel, which is drawn into the jets of reactant hot air, produces jets of hot gas, shown schematically by wavy arrows. The jets of hot gas supply energy to the scrap metal pile 9 located in the interior 7 of the electric arc furnace 2. The blowing apparatus 6a, 6b, 6c preferably comprise overall six nozzles 10a, 10b, 10c, 10d, 10e, 10f all with nozzle openings. FIG. 1 shows the apparatus during a first phase of the inventive method, in which energy is supplied to the metal scrap pile 9 by jets of hot gas. The hot gas is supplied in six jets, wherein each of the supplied jets supplies a sixth of the overall quantity of hot gas supplied. The nozzles 10a, 10b, 10c, 10d, 10e, 10f are in this embodiment arranged in three nozzle heads 11a, 11b, 11c, which heads are arranged in openings provided in the cover wall 5 of the electric arc furnace 2 in order to introduce electrodes. Each nozzle head 11a, 11b, 11c in this embodiment has two nozzles and thus has two nozzle openings. The nozzle openings of all nozzles 10a, 10b, 10c, 10d, 10e, 10f have the same diameter. The distance between the nozzles 10a, 10b, 10c, 10d, 10e, 10f is preferably at least twice the diameter of the nozzle openings of the nozzles 10a, 10b, 10c, 10d, 10e, 10f. As a result, the distance between the jets of reactant hot air, when the air is exiting the blowing apparatus 6a, 6b, 6c, is at least twice the diameter of the jets upon exit. In the exemplary configuration shown, the distance between the jets of hot gas in the scrap metal pile is at least five times the diameter of the jets of reactant hot air upon exiting the blowing apparatus 6a, 6b, 6c.

(4) For improved clarity, the representation of electrodes and/or apparatus for routing electrodes into the interior was omitted. Similarly, the representation of the second phase of the inventive method, in which energy is supplied by means of electric arcs, is omitted.

(5) FIG. 2 shows the electric arc furnace from FIG. 1 in a top view from above onto the cover wall 5. The reference characters are used in the same way as in FIG. 1. The six jets of hot air are also shown as wavy arrows.

(6) The present invention is explained by an example with the aid of the following exemplary embodiment:

(7) In an 80-t electric arc furnace, scrap is charged into two baskets. After the first basket, reactant hot air (18000 Nm3/h), enriched to an oxygen content of 35%, is blasted at a temperature of 1200 C. through six nozzles with 3000 Nm3 per hour and nozzle. Natural gas is supplied to the jets of reactant hot airthe 18000 Nm3/h a quantity of 3200 Nm3/h. Jets of hot gas develop by burning natural gas into the jets of reactant hot air. The nozzles are aligned such that the jets of hot gas are not able to join together in the scrap metal pile and they instead pass through the scrap metal pile in a relatively evenly distributed fashion. In a second phase, the jets of hot gas do not supply gas. Then the electric arcs are produced.

(8) Although the invention was illustrated and described in more detail by the preferred exemplary embodiments, the invention is not restricted by the disclosed examples and other variations can be derived herefrom by the person skilled in the art, without departing from the protective scope of the invention.

LIST OF REFERENCE CHARACTERS

(9) TABLE-US-00001 1 inventive apparatus 2 electric arc furnace 3 base 4 side wall 5 cover wall 6a, 6b, 6c blowing apparatus 7 interior 8 fuel supply apparatus 9 metal scrap pile 10a, 10b, 10c, nozzles 10d, 10e, 10f 11a, 11b, 11c nozzle head

LIST OF CITATIONS

Patent Literature

(10) DE19521518

(11) DE10317195