ANNEALING LINE FOR A STEEL STRIP

Abstract

An annealing line for a steel strip, a device for use in such an annealing line and a method for annealing a steel strip. The annealing line including a connecting chamber connecting a first heating section and a second heating section, wherein one or more devices, located in the connecting chamber, are arranged on one or both sides of the steel strip for oxidising the steel strip using an oxidising gas mixture, each device having a body including an internal chamber and one or more openings to project the oxidising gas mixture onto the surface of the steel strip.

Claims

1. An annealing line for a steel strip comprising a connecting chamber connecting a first heating section and a second heating section, wherein one or more devices, located in the connecting chamber, are arranged on one or both sides of the steel strip for oxidising the steel strip using an oxidising gas mixture, each device having a body comprising an internal chamber and one or more openings to project the oxidising gas mixture onto the surface of the steel strip, wherein the internal chamber is divided into three or more compartments.

2. The annealing line according to claim 1, wherein three said compartments of the internal chamber comprises respectively a central compartment and a first pair of outer compartments, each outer compartment is positioned adjacent to the central compartment.

3. The annealing line according to claim 2, wherein the internal chamber further comprises a second pair of outer compartments, each outer compartment is positioned adjacent to the first pair of outer compartments.

4. The annealing line according to claim 3, wherein the internal chamber further comprises one or more additional pairs of outer compartments, each outer compartment of each additional pair of outer compartments is positioned adjacent to an outer compartment of another pair of outer compartments.

5. The annealing line according to claim 1, wherein the device has an elongated shape.

6. The annealing line according to claim 2, wherein the device comprises inlet means for providing the oxidising gas mixture, a first inlet means coupled to a first conduct for providing the oxidising gas mixture to the central compartment, the device further comprises a second inlet means coupled to a second conduct for providing the oxidising gas mixture to the first pair of outer compartments.

7. The annealing line according to claim 6, wherein the device further comprises third inlet means coupled to a third conduct, for providing the oxidising gas mixture to the second pair of outer compartments.

8. The annealing line according to claim 6, wherein the second conduct extends via a first additional conduct to the first pair of outer compartments for providing the oxidising gas mixture.

9. The annealing line according to claim 6, wherein the third conduct extends via a second additional conduct to the second pair of outer compartments for providing the oxidising gas mixture.

10. The annealing line according to claim 6, wherein a further conduct extends via a further additional conduct to an additional pair of outer compartments for providing the oxidising gas mixture.

11. The annealing line according to claim 1, wherein the device is rotatable along an axis parallel to a width direction of the steel strip, attuned to achieve a preferred angle between the axis of projection of the one or more openings and the steel strip during processing.

12. The annealing line according to claim 1, wherein the one or more openings are arranged in a sunk manner.

13. A device for use in an annealing line for a steel strip comprising a connecting chamber connecting a first heating section and a second heating section, said device having a body comprising an internal chamber and one or more openings to project the oxidising gas mixture onto the surface of the steel strip, wherein the internal chamber is divided into three or more compartments.

14. A method for annealing a steel strip using the annealing line according to claim 1, the steel strip having a variable width during the annealing of the steel strip, wherein each compartment of the internal chamber is provided with the oxidising gas mixture depending on a width of the steel strip.

15. The annealing line according to claim 1, wherein three said compartments of the internal chamber comprises a central compartment and a first pair of outer compartments, the pair of outer compartments is controllable together.

16. The annealing line according to claim 2, wherein the internal chamber further comprises a second pair of outer compartments, the second pair of outer compartments is controllable together.

17. The annealing line according to claim 3, wherein the internal chamber further comprises one or more additional pairs of outer compartments, the outer compartments in each additional pair is controllable together.

18. The annealing line according to claim 1, wherein the one or more openings, are embodied as one or more nozzles or slits, and are arranged in a sunk manner.

Description

[0028] In the drawing:

[0029] FIG. 1 shows an annealing line in schematic form;

[0030] FIG. 2 shows the steel strip and a device for oxidising the steel strip in the connecting chamber;

[0031] FIG. 3 shows the device in more detailed view;

[0032] FIG. 4 shows the device in an open view without the surrounding body in different angles;

[0033] FIG. 5 shows the internal configuration of the device and particularly the openings in more detail;

[0034] FIG. 6 shows a preferred embodiment of the device;

[0035] FIG. 7 shows the openings in more detail;

[0036] Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

[0037] FIG. 1 relates to an annealing line (1) for a steel strip (2) which, as such, is well known to a person skilled in the art. The annealing line comprises a first heating section (3), for example a direct flame furnace section (DFF) or a non-oxidising furnace (NOF), a connecting chamber (4) connecting the first heating section (3) and a second heating section (5), for example a radiant tube furnace section (RTF). A steel strip (2) is processed, or annealed, in the direction of (A) and optionally comprises a cooling section (22) and/or a hot dip galvanising line (19). In the connecting chamber (4) one or more devices (6) are located, arranged on one or both sides of the steel strip (2) for oxidising the steel strip (2) using an oxidising gas mixture.

[0038] FIG. 2 shows the steel strip (2) travelling in the direction of (B) in the connecting chamber (4) (the connecting chamber itself is not shown as the location is clearly shown in FIG. 1). The one or more devices (6), having a body (7) are, in use, arranged on one or both sides of the steel strip (2). In this embodiment one device (6) on both sides of the steel strip is shown, but other configurations are also possible. When the steel strip travels in the direction of (B), an oxidising gas mixture will flow out of the one or more openings (9) (more clearly shown in FIGS. 3, 4 and 5) to the surface of the steel strip (2) and will oxidise the alloying elements present.

[0039] FIG. 3 shows the device (6) in more detail. The device (6) has a body (7) comprising an internal chamber (8) and one or more openings (9) to project the oxidising gas mixture onto the surface of the steel strip (2) (not shown here, but clearly shown in FIG. 2). The internal chamber (8) is divided into three or more compartments (10, 11, 12). In this particular figure, 5 compartments are shown. More particularly, the internal chamber (8) comprises a central compartment (10) and a first pair of outer compartments (11). Each outer compartment (11) is positioned adjacent to the central compartment (10) and the pair of outer compartments (11) is controllable together. The width of the central compartment (10) is indicated by (C). For the narrowest width of steel strips (2) it is sufficient that only oxidising gas mixture will flow through the central compartment (10) via the one or more openings (9) to the steel strip (2). The width (C) thus corresponds to the narrowest width of steel strips (2) to be oxidised. Therefore the central compartment (10) is always provided with the oxidising gas mixture when the one or more devices (6) are in use.

[0040] The first pair of outer compartments (11) is controllable together, meaning the oxidising gas mixture is always evenly distributed over the two compartments with oxidising gas mixture, which will be explained later.

[0041] The first pair of outer compartments (11) consists of two outer compartments (11), each outer compartment (11) is positioned adjacent to the central compartment (10). In the embodiment shown, the two outer compartments (11) are positioned adjacent to the central compartment (10) in a symmetrical way, but naturally, other configurations may be possible that are attuned to the specific needs of the steel strip (2) to be oxidised. The width of the central compartment (10) together with the first pair of outer compartments is indicated with (D). The outer compartments (11) adjacent to the central compartment (10) are used when the width of the steel strip is wider than the width of the central compartment (C). In that case the central compartment (10), together with the first pair of outer components will project the oxidising gas onto the steel strip. The first pair of outer compartments (11) is controllable together, meaning that the pair is always controlled as one unit, split into two parts. This will guarantee a more even flow of oxidising gas medium to the steel strip (2). The same principle applies to the second and further pairs of outer compartments (11, 12).

[0042] The internal chamber (8) is configured as further having a second pair of outer compartments (12), each outer compartment (12) is positioned adjacent to the first pair of outer compartments (11) and the second pair of outer compartments (12) is controllable together. When the width of the steel strip to be oxidised is wider than the width of the central compartment and the first pair of outer compartments, indicated with (D), two more outer compartments will be used, leading to the oxidising of an even wider steel strip (2), with a total of five compartments, indicated with (E).

[0043] The maximal width of the steel strip (2) to be oxidised in this embodiment is indicated with (E). This means that in this embodiment the central compartment (10) as well as the first pair of outer compartments (11) and the second pair of outer compartments (12) are used. However, depending on the specifications of the steel strip (2) to be oxidised, one or more additional pairs of outer compartments could be added. Each outer compartment of each additional pair of outer compartments is positioned adjacent to an outer compartment of another pair of outer compartments and the outer compartments in each additional pair is controllable together.

[0044] As is shown in this figure, but also in FIGS. 2 and 4 to 6, the device (6) has an elongated shape. This is particularly beneficial because of the different widths of steel strips (2) to be oxidised. In this way a one-on-one relation between the total width (C, D, E) of the active part of the device (6) and the steel strip (2) to be oxidised could be achieved.

[0045] FIG. 4 is, for clarity purposes, split into FIGS. 4a, 4b and 4c. FIG. 4a shows a configuration of the device (6) comprising inlet means (13, 14, 15) for providing the oxidising gas mixture, a first inlet means (13) coupled to a first conduct (18) for providing the oxidising gas mixture to the central compartment (10) and the device further comprises a second inlet means (14) coupled to a second conduct (16) for providing the oxidising gas mixture to the first pair of outer compartments (11). As explained earlier, the central compartment (10) will provide the oxidising gas mixture via the one or more openings (9) to the steel strip (2) having a maximal width equal to the width (C) of the central compartment (10). Further, the second conduct (16) extending via a first additional conduct (20) to the first pair of outer compartments (11) for providing the oxidising gas mixture is shown.

[0046] FIG. 4b shows the same configuration, but from a different angle. In this figure is shown, more clearly than in FIG. 4a, that the device (6) further comprises third inlet means (15) coupled to a third conduct (17) extending via a second additional conduct (21) for providing the oxidising gas mixture to the second pair of outer compartments (12).

[0047] FIG. 4c does not show, for clarity purposes, the first inlet means (13) and the first conduct (18). This allows a more detailed view of the configuration of the second inlet means (14) coupled to a second conduct (16) and a first additional conduct (20) for providing the oxidising gas mixture to the first pair of outer compartments (11). It also shows in more detail than FIGS. 4a and 4b the configuration of the third inlet means (15) coupled to a third conduct (17) extending via a second additional conduct (21) to the second pair of outer compartments (12) for providing the oxidising gas medium.

[0048] To sum up the preferred combinations a table is shown underneath to provide an easy overview:

TABLE-US-00001 Additional Width Compartments Conducts conducts ≤C 10 13 + 18 — >C, ≤D 10 + 11 13 + 18 + 14 + 16 20 >D, ≤E 10 + 11 + 12 13 + 18 + 14 + 16 + 15 + 17 21

[0049] FIG. 5 shows the device in an open view without the surrounding body. The openings (9) are clearly shown and in this embodiment are shown as a plurality of nozzles, but other openings, like slits, and other configurations, are also possible. Preferably, the one or more openings are embodied as nozzles or slits. In a part of FIG. 5 nozzles are shown in open view to provide a more detailed view. Also the configuration of the inlet means (13, 14, 15) and conducts (16, 17, 18) of the device are shown, where more details can be found of in FIG. 4. The one or more openings (9) are arranged in a sunk manner. Details of the positioning of the openings (9) can be found in FIG. 7.

[0050] FIG. 6 shows that the device (6) is rotatable along an axis parallel to the width direction of the steel strip (2), attuned to achieve a preferred angle between the axis of projection of the one or more openings (9) and the steel strip (2) during processing. The rotation direction is indicated with (F) and can be adjusted according to the specifications of the steel strip (2) to be oxidised.

[0051] FIG. 7 shows the positioning of an opening (9) in the device (6) through section (L). The orifice (23) of the opening is clearly shown. The opening (9) protrudes into the interior of the device (6) where the oxidising gas mixture can flow through the orifice (23) and end (24) of the opening (9) to the steel strip (2). The openings (9) are replaceable and other designs and/or sizes than depicted here are imaginable with respect to the desired processing parameters.

[0052] Although the invention has been discussed in the foregoing with reference to exemplary embodiments of the invention, the invention is not restricted to these particular embodiments which can be varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary, the embodiments are merely intended to explain the wording of the appended claims without intent to limit the claims to the embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using these exemplary embodiments.