Afterburner chamber system for heat removal from a melting unit

Abstract

The present invention is in the field of steelmaking technology and describes an afterburner system for a melting unit for heat removal from the bottom of an afterburner. One or more cavities extend below the bottom, and flow channels are arranged on the outside of the afterburner walls, connecting to the cavities. The cavities are supported, for example, by pipes, honeycomb beams, I-beams, or support legs. The invention further comprises a method for heat removal from the afterburner system. In this method, a fluid, preferably air, flows through the cavities and flow channels.

Description

field of technology

[0001] The present invention is in the field of steelmaking technology and describes an afterburner system for a melting unit, preferably an electric arc furnace, comprising an afterburner chamber with walls and a device for heat dissipation from the bottom of the afterburner chamber. The melting unit can, for example, also be an AOD (Argon Oxygen Decarburization) converter. Typically, water-cooled panels or linings are located on the inner walls and in the ceiling area of ​​an afterburner chamber. Separated solids can be discharged through gate elements.

[0002] The afterburner, also called a separation chamber or dropout box (DOP), can be supplied with at least one hot gas, preferably exhaust gas from the melting unit, and has at least one opening through which the gas can exit. Afterburning processes of combustible components of the exhaust gas can occur in 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. State of the art

[0003] US3378249A shows a cooler located between the furnace chamber of a blast furnace and its foundation for cooling the furnace floor. The cooler consists of several sections, each with inlet and outlet channels for a cooling medium.

[0004] US3820770 shows a structure comprising multiple layers of refractory material beneath the furnace chamber of a furnace, such as a blast furnace. Optionally, a passage for cooling media extends through the lowest layers. Pipes carrying air or water are embedded in the floor. Summary of the invention

[0005] The object of the present invention is to provide an afterburner system for a melting unit, comprising an afterburner chamber and a device for heat dissipation from the bottom of the afterburner chamber. This cools the bottom of the afterburner chamber and reduces the heat input into underlying areas such as a foundation or the ground.

[0006] Furthermore, the extracted heat can be used for technical purposes.

[0007] According to the invention, one or more cavities extend below the floor, the greatest extent of which is in the horizontal direction, and flow channels are arranged at least two points on the outside of the walls of the afterburner chamber, which are connected to the cavities.

[0008] 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.

[0009] 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.

[0010] In a preferred embodiment, the afterburner system comprises tubes such that the floor is supported by the tubes and the tubes are capable of allowing flow in a horizontal direction.

[0011] 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.

[0012] In another preferred embodiment, the tubes have a circular cross-section, with an inner radius between 100 mm and 300 mm.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] Furthermore, a method for heat removal from an 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.

[0019] In a preferred method, the fluid is a gas, preferably air.

[0020] In another preferred method, the fluid is a liquid, preferably water.

[0021] In another preferred method, the removed heat is used at least partially to heat scrap metal.

[0022] 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.

[0023] In another preferred method, the flow can be driven by a conveying device, preferably a blower.

[0024] In another preferred method, the flow can be driven by a conveying device, preferably a pump.

[0025] 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

[0026] 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 afterburner chamber system. Fig. 2 Schematic or exemplary cross-sectional views of the floor and cavities under the floor of the afterburner chamber system. Description of the embodiments

[0027] Fig. 1 Figure 1 shows an embodiment of the invention in the form of a top view or a sectional view of an afterburner system 1. The afterburner system 1 comprises an afterburner chamber 2 and a device for heat dissipation from a base 15 of the afterburner chamber 2. A gas, preferably exhaust gas from a melting unit, can be supplied to the afterburner chamber 2 via a first opening 5. The gas can exit the afterburner chamber 2 via a second opening 6. A cavity 16 extends below the base 15. The afterburner chamber 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 after passing through the cavity 16 via a second flow channel 17 with an outlet 11.

[0028] Fig. 2 Figure 1 shows schematic and exemplary cross-sectional views of the floor 15 and of cavities 16 beneath the floor 15 of the afterburner chamber system 1. In case a), the cavity contains honeycomb supports; in case b), it contains I-beams with openings in the webs; in case c), it contains pipes; and in case d), it contains support feet. Flow can propagate undisturbed into the cavity because the support feet do not represent large-area flow obstructions.

[0029] The in Fig. 2 The depicted designs provide support for the ground 15 and allow flow through the cavities 16 under the ground 15.

[0030] 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

[0031] 1 Afterburner system 2 Afterburner chamber 3 Walls 5 First opening 6 Second opening 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 a) Cavity with honeycomb supports b) Cavity with I-beams c) Cavity with pipes d) Cavity with support feet

Claims

1. Afterburner system (1) for a melting unit, preferably an electric arc furnace, comprising an afterburner chamber (2) with walls (3) and a device for heat removal from a bottom (15) of the afterburner chamber (2), wherein at least one exhaust gas from the melting unit can be supplied to the afterburner chamber (2), characterized by that one or more cavities (16) extend below the floor (15), the greatest extent of the cavities (16) being in a horizontal direction, with flow channels (17, 18) arranged at least at two points on the outside of the walls (3) of the afterburner chamber (2), which are connected to the cavities (16).

2. Afterburner system (1) 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. Afterburner system (1) 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. Afterburner system (1) 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. Afterburner system (1) 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. Afterburner chamber system (1) according to claim 1, wherein the cavity (16) comprises support feet (23), wherein the floor (15) is supported by the support feet (23).

7. Afterburner system (1) 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 afterburner system (1) according to one of claims 1 - 7, characterized by that the 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 the heat removed is at least partially used to heat scrap.

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

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

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

15. Method according to one of claims 8 - 14, wherein the gas supplies heat as a heat transfer medium to a heat pump.

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