Afterburner chamber system for heat removal from an electric arc furnace

Abstract

The present invention is in the field of steelmaking technology and describes an electric arc furnace afterburner system (10) comprising an electric arc furnace (30) for heat removal from a floor (15) of an afterburner chamber (2). Below the floor (15) extend one or more cavities (16), and flow channels (17, 18) are arranged on the outside of the walls (3) of the afterburner chamber (2), which are connected to the cavities (16). The cavities (16) are supported, for example, by pipes, honeycomb supports, I-beams, or support feet. The invention further comprises a method for heat removal from the electric arc furnace afterburner system (10). In this method, the cavities (16) and flow channels (17, 18) are circulated by a fluid, preferably air.

Description

field of technology

[0001] The present invention is in the field of steelmaking technology and describes an electric arc furnace afterburner system comprising an electric arc furnace, an exhaust duct, an afterburner comprising walls and a floor, wherein the exhaust duct runs from the electric arc furnace to the afterburner. State of the art

[0002] Typically, the inner walls and ceiling of an afterburner chamber contain water-cooled panels or linings. Separated solids can be vented through door elements.

[0003] An afterburner, also called a dropout box (DOP), is designed such that at least one hot gas, preferably exhaust gas from an electric arc furnace, can be supplied to it via the exhaust pipe, and the afterburner has an opening through which the gas can exit. Afterburning processes involving combustible components of the hot gas or exhaust gas can occur within the afterburner. Furthermore, changes in the direction of the exhaust gas flow cause coarse particles to be at least partially separated from the typically hot exhaust gas. Summary of the invention Technical task

[0004] The object of the present invention is to provide an electric arc furnace afterburner system comprising an electric arc furnace, an exhaust duct, an afterburner comprising walls and a floor, and a device for heat removal from the floor of the afterburner. Technical solution

[0005] The task is solved by a Electric arc furnace afterburner system (10) comprising an electric arc furnace (30), an exhaust duct (31), an afterburner chamber (2) comprising walls (3) and a floor (15), wherein the exhaust duct (31) extends from the electric arc furnace (30) to the afterburner chamber , characterized bythat it also includes a device for heat removal from the floor (15) of the afterburner chamber (2), and that one or more cavities (16) extend adjoining the floor (15) at the bottom, the greatest extent of the cavities (16) being in a horizontal direction, wherein at least two locations outside the afterburner chamber (2) on the walls (3) flow channels (17, 18) are arranged in an at least partially vertical orientation, which are connected to the cavities (16).

[0006] The exhaust gas line runs from the electric arc furnace to the afterburner chamber. The exhaust gas from the electric arc furnace is fed into the afterburner chamber, preferably from above, through a first opening in the exhaust gas line.

[0007] The afterburner chamber is a space enclosed by boundaries, with a floor, walls and a ceiling or lid.

[0008] An inner side of the walls forms the boundary to the interior of the afterburner chamber, while an outer side of the walls separates the afterburner chamber from the surrounding environment. According to the invention, one or more cavities extend along the bottom, adjacent to the floor. "Abutting the floor" is understood to mean the outer side of the combustion chamber, adjacent to the floor.

[0009] The greatest extent of the cavities is in the horizontal direction, with flow channels arranged at least partially vertically at two points on the outside of the walls of the afterburner chamber, which are connected to the cavities. Advantageous effects of the invention

[0010] This cools the floor of the afterburner chamber and reduces the heat input into underlying areas such as a foundation or soil.

[0011] Furthermore, the dissipated heat can be used for technical purposes. The cavity can, for example, be designed in the form of adjacent channels. A cooling medium, such as ambient air, can be introduced into these channels via flow channels located on the outside of the afterburner chamber, and then removed again in a heated form.

[0012] On the one hand, this reduces the heat input from the bottom of the afterburner chamber into the ground on which the afterburner system is located. On the other hand, heat transferred from the exhaust gas to the bottom of the afterburner chamber can be used to heat a cooling medium and thus be supplied to other processes as recovered heat. These can include, for example, processes for preheating feedstocks, general heating applications, or heat pump processes.

[0013] In a preferred embodiment, the electric arc furnace afterburner system comprises tubes such that the floor is supported by the tubes and the tubes are capable of horizontal flow.

[0014] The cavity(s) are thus formed by pipes arranged side by side and / or one above the other. Such an arrangement allows for easy cleaning of the cavities, for example using brushes and the like inserted through appropriate access openings.

[0015] In another preferred embodiment, the tubes have a circular cross-section, with an inner radius between 100 mm and 300 mm.

[0016] In a further preferred embodiment, the cavity comprises honeycomb supports, wherein the bottom is supported by the honeycomb supports and the cavity is permeable to flow in a horizontal direction along the honeycomb supports and transversely to the honeycomb supports.

[0017] In a further preferred embodiment, the cavity comprises I-beams, wherein the bottom is supported by the I-beams and webs of the I-beams have openings so that the cavity can be permeated in a horizontal direction along the I-beams and transversely to the I-beams.

[0018] In a further preferred embodiment, the cavity comprises support feet, wherein the bottom is supported against the ground by the support feet. This type of support ensures that the flow within the cavity can propagate as undisturbed as possible.

[0019] In a further preferred embodiment, the vertical extent of at least one flow channel is at least 1 m, preferably at least 3 m, and particularly preferably at least 5 m.

[0020] By vertically orienting at least one flow channel, a chimney effect can be achieved as the cooling medium heats up, provided the design is appropriate. This allows the flow of the cooling medium to be driven, at least partially, by natural convection, and an additional drive mechanism is not necessarily required.

[0021] Furthermore, a method for heat removal from an electric arc furnace afterburner system is described, wherein the cavities and flow channels are traversed by a fluid; thus, a fluid flow takes place. The fluid acts as a cooling medium.

[0022] In a preferred method, the fluid is a gas, preferably air.

[0023] In another preferred method, the fluid is a liquid, preferably water.

[0024] In another preferred method, the removed heat is used at least partially to heat scrap metal.

[0025] In another preferred method, the flow is achieved by natural convection. It is also conceivable that the flow of the cooling medium is driven solely by natural convection. Calculations have shown that, in an afterburner chamber system for a typical electric arc furnace for steel production, heat flux densities in the region of the base in this way range from 0.5 kW / m²< to 1 kW / m²<, with the heating of the cooling air being between 8 K and 15 K.

[0026] In another preferred method, the flow can be driven by a conveying device, preferably a blower.

[0027] In another preferred method, the flow can be driven by a conveying device, preferably a pump.

[0028] In another preferred method, the gas acts as a heat transfer medium for a heat pump. If the temperature level of the recovered heat is too low for certain subsequent processes, it is possible, for example, to raise it to the required level by using a heat pump. Brief description of the drawings

[0029] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. This shows: Fig. 1 A schematic or exemplary top view or sectional view of an electric arc furnace afterburner system. Fig. 2Schematic or exemplary cross-sectional views of the floor and cavities under the floor of the electric arc furnace afterburner system. Fig. 3 A schematic representation of the electric arc furnace afterburner system, comprising an electric arc furnace, an exhaust pipe, and an afterburner. Description of the embodiments

[0030] Fig. 1Figure 10 shows an embodiment of the invention in the form of a top view or a sectional view of an afterburner system. The electric arc furnace afterburner system 10 comprises an afterburner 2 and a device for heat dissipation from a base 15 of the afterburner 2. A gas, preferably exhaust gas from an electric arc furnace 30, can be supplied to the afterburner 2 via a first opening 5. The gas can exit the afterburner 2 via a second opening 6. A cavity 16 extends below the base 15. The afterburner 2 is laterally bounded by walls 3. Air, for example ambient air, can be supplied to the cavity 16 via a first flow channel 18 with an inlet 12. This air is discharged through the cavity 16 via a second flow channel 17 with an outlet 11.

[0031] For the sake of clarity, a representation of the exhaust pipe 31 and the electric arc furnace 30 is omitted.

[0032] Fig. 2 Figure 1 shows schematic and exemplary cross-sectional views of the floor 15 and cavities 16 beneath the floor 15 of the electric arc furnace afterburner system 10. In case a), the cavity contains honeycomb supports 20; in case b), it contains I-beams 21 with openings in the webs; in case c), it contains pipes 22; and in case d), it contains a cavity with support feet 23. Flow can propagate undisturbed into the cavity because the support feet 23 do not represent large-area flow obstructions.

[0033] The in Fig. 2 The depicted designs provide support for the ground 15 and allow flow through the cavities 16 under the ground 15.

[0034] Fig. 3 Figure 1 shows a schematic representation of the electric arc furnace afterburner system 10, comprising an electric arc furnace 30, an exhaust pipe 31, and an afterburner 2, wherein the exhaust pipe 31 runs from the electric arc furnace 30 to the afterburner 2.

[0035] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention. Reference symbol list

[0036] 2 Afterburner 3 Walls 5 First opening 6 Second opening 10 Electric arc furnace afterburner system 11 Outlet 12 Inlet 15 Bottom 16 Cavity 17 Second flow channel 18 First flow channel 20 Honeycomb support 21 I-beam 21a Opening 22 Pipes 23 Support feet 30 Electric arc furnace 31 Exhaust pipe a) Cavity with honeycomb support b) Cavity with I-beams c) Cavity with pipes d) Cavity with support feet

Claims

1. Electric arc furnace afterburner system (10) comprising an electric arc furnace (30), an exhaust duct (31), an afterburner chamber (2) comprising walls (3) and a floor (15), wherein the exhaust duct (31) extends from the electric arc furnace (30) to the afterburner chamber , characterized by that it also includes a device for heat removal from the floor (15) of the afterburner chamber (2), and that one or more cavities (16) extend adjoining the bottom of the floor (15), the greatest extent of the cavities (16) being in a horizontal direction, wherein at least two points outside the afterburner chamber (2) on the walls (3) flow channels (17, 18) are arranged in an at least partially vertical orientation, which are connected to the cavities (16).

2. Electric arc furnace afterburner system (10) according to claim 1, wherein the cavity (16) comprises tubes (22) such that the bottom (15) is supported by the tubes (22) and the tubes (22) are capable of horizontal flow.

3. Electric arc furnace afterburner system (10) according to claim 2, wherein the tubes (22) have a circular cross-section, wherein an inner radius is between 100 mm and 300 mm.

4. Electric arc furnace afterburner system (10) according to claim 1, wherein the cavity (16) comprises honeycomb supports (20), wherein the bottom (15) is supported by the honeycomb supports (20) and the cavity (16) is permeable in a horizontal direction along the honeycomb supports (20) and transversely to the honeycomb supports (20).

5. Electric arc furnace afterburner system (10) according to claim 1, wherein the cavity (16) comprises I-beams (21), wherein the bottom (15) is supported by the I-beams (21) and webs of the I-beams have openings (21a) so that the cavity (16) can be permeated in a horizontal direction along the I-beams (21) and transversely to the I-beams (21).

6. Electric arc furnace afterburner system (10) according to claim 1, wherein the cavity (16) comprises support feet (23), wherein the floor (15) is supported by the support feet (23).

7. Electric arc furnace afterburner system (10) according to one of claims 1 - 6, wherein the vertical extent of at least one flow channel (17, 18) is at least 1 m, preferably at least 3 m, particularly preferably at least 5 m.

8. Method for heat removal from an electric arc furnace afterburner system (10) according to one of claims 1 - 7, characterized by thatthe cavities (16) and flow channels (17, 18) are through which a fluid flows.

9. The method of claim 8, wherein the fluid is a gas, preferably air.

10. The method of claim 8, wherein the fluid is a liquid, preferably water.

11. Method according to one of claims 8 - 10, wherein flow is effected by natural convection.

12. Method according to claim 9, wherein a flow through a conveying device, preferably a blower, can be driven.

13. Method according to claim 10, wherein a flow can be driven by a conveying device, preferably a pump.

14. Method according to claim 9, wherein the gas supplies heat as a heat transfer medium to a heat pump.

15. Method according to one of claims 8 - 10, wherein the heat removed is at least partially used to heat scrap.

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