Cooling system for cooling metal rolling stock

Abstract

A cooling system (2) for cooling metal rolling stock. A plurality of cooling bars (8) for applying a coolant onto the rolling stock, one dedicated coolant supply line (36) for each cooling bar (8), and a feed system (9) for guiding the coolant to the coolant supply lines (36). Each cooling bar (8) is connected to the feed system (9) via a dedicated coolant supply line (36). A bypass line (48, 52) for discharging a coolant flow from the feed system (9), is connected on the input side to a connection element (51, 53) of the feed system (9).

Claims

1. A cooling system (2) for cooling metal rolling stock, comprising: a plurality of cooling bars (8) configured for applying a coolant to the rolling stock; a respective dedicated coolant supply line (36) for each of the cooling bars (8); a feed line system (9) for directing the coolant to the respective dedicated coolant supply lines (36), wherein each of the cooling bars (8) is connected to the feed line system (9) by its dedicated coolant supply line (36); a bypass line (48, 52) for discharging a coolant flow from the feed line system (9), the bypass line is connected on an input side to a connection element (51,53) of the feed line system (9); a coolant reservoir (4), to which the feed line system (9) is connected; a scale channel (42), a scale settling tank (44) connected to the scale channel (42); and a further bypass line (48, 52) connected on the input side to another connection element (51, 53) of the feed line system (9), wherein one of the two bypass lines (48, 52) is connected on an output side to the coolant reservoir (4) or to a further connection element (55) of the feed line system (9) and the other of the two bypass lines (48, 52) opens out on a further output side into the scale channel (42) or into the scale settling tank (44).

2. The cooling system (2) as claimed in claim 1, wherein the coolant reservoir (4) is an elevated tank.

3. The cooling system (2) as claimed in claim 1, wherein the bypass line (48, 52) is connected on the output side to the coolant reservoir (4).

4. The cooling system (2) as claimed in claim 1, wherein the bypass line (48, 52) is connected on the output side to the further connection element (55) of the feed line system (9).

5. The cooling system (2) as claimed in claim 1, further comprising: a coolant pump (20) configured for increasing a coolant pressure in the feed line system (9), wherein the further connection element (55) is arranged upstream of the coolant pump (20) and the bypass line (48, 52) is connected on the output side to the additional connection element (55); and the coolant pump (20) has a frequency-controlled drive.

6. The cooling system (2) as claimed in claim 1, wherein the bypass line (48, 52) opens out on the output side into the scale channel (42) or into the scale settling tank (44).

7. The cooling system (2) as claimed in claim 1, further comprising a shut-off member (50, 54) arranged in the bypass line (48, 52), and at least one further shut-off member (40) for interrupting a coolant feed to at least one of the cooling bars (8).

8. The cooling system (2) as claimed in claim 7, further comprising the shut-off member (50, 54) which is arranged in the bypass line (48, 52) and the further shut-off member (40) are both configured to have at least substantially the same switching times.

9. The cooling system (2) as claimed in claim 7, further comprising the further shut-off member (40) is arranged in the feed line system (9) or in one of the coolant supply lines (36).

10. A method for operating a cooling system (2) as claimed in claim 1, comprising: discharging a coolant flow from the feed line system (9) via the bypass line (48, 52), which is connected on the input side to the connection element (51, 53) of the feed line system (9); sending the coolant flow via the bypass line (48, 52) into the coolant reservoir (4) of the cooling system (2) or sending the coolant flow back into the feed line system (9); and sending a further coolant flow is via the further bypass line (48,52) into the scale channel (42) into the scale settling tank (44) of the cooling system (2).

11. The method as claimed in claim 10, further comprising sending the coolant flow from the bypass line (48, 52) directly into the coolant reservoir (4) of the cooling system (2).

12. The method as claimed in claim 10, further comprising sending the coolant flow from the bypass line (48, 52) directly back into the feed line system (9), so that the coolant flow is reintroduced into the feed line system (9) upstream of a coolant pump (20) arranged in the feed line system (9).

13. The method as claimed in claim 10, further comprising sending the further coolant flow from the further bypass line (48, 52) directly into a scale channel (42) or into a scale settling tank (44) of the cooling system (2).

14. The cooling system as claimed in claim 1, wherein there is precisely one of the respective coolant supply lines (36) for each of the cooling bars.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cooling system with a bypass line connected on the input side to a distributor line and opens out on the output side into a scale settling tank;

(2) FIG. 2 shows another cooling system with a bypass line connected on the input side to a distributor line and is connected on the output side to a coolant reservoir;

(3) FIG. 3 shows a further cooling system with a bypass line connected on the input side to a main line and is connected on the output side to a coolant reservoir;

(4) FIG. 4 shows yet another cooling system with a bypass line connected both on the input side and on the output side to a main line; and

(5) FIG. 5 shows yet a further cooling system with a first bypass line and a second bypass line, wherein the first bypass line is connected on the input side to a main line and is connected on the output side to a coolant reservoir and the second bypass line is connected on the input side to a distributor line and opens out on the output side into a scale settling tank.

DESCRIPTION OF EMBODIMENTS

(6) FIG. 1 shows a diagram of a cooling system 2 for cooling a hot-rolled rolling stock (rolling stock not represented in the figure).

(7) The cooling system 2 comprises a coolant reservoir 4, formed as an elevated tank, for storing a coolant 6. In the present exemplary embodiment, the coolant 6 is water. The cooling system 2 also comprises a number of cooling bars 8 for applying the coolant 6 to the rolling stock. In addition, the cooling system 2 has a feed line system 9.

(8) The feed line system 9 comprises a first main line 10 and a first distributor line 12. The first main line 10 is connected on the input side directly to the coolant reservoir 4. On the output side, the first main line 10 is connected directly to the first distributor line 12.

(9) The feed line system 9 comprises a second main line 14 and a second distributor line 16. The second main line 14 is connected on the input side directly to the coolant reservoir 4. On the output side, the second main line 14 is connected directly to the second distributor line 16. The first main line 10 and the second main line 14 are connected to one another by a connecting line 18.

(10) The cooling system 2 comprises a coolant pump 20, which is arranged in the second main line 14 and has a frequency-controlled drive. The coolant pump 20 is arranged between a first servicing flap valve 22 and a second servicing flap valve 24, which are arranged in the second main line 14. The servicing flap valves 22, 24 isolate the coolant pump 20 for servicing and/or repair purposes and thereby allowing servicing, repair or exchange to be performed without the coolant 6 having to be removed from upstream of the valves.

(11) A shut-off member 26, formed as a valve, is arranged in the connecting line 18, which connects the first main line 10 to the second main line 14, for opening and closing the connecting line 18. A shut-off member 28, formed as a valve is, arranged in the second main line 14 between the coolant pump 20 and the second distributor line 16, for opening and closing the second main line 14.

(12) The cooling bars 8 of the cooling system 2 are arranged along a cooling zone 30, through which the rolling stock is passed for its cooling. The cooling zone 30 in the present embodiment is divided into a first cooling zone section 32 and a second cooling zone section 34. The terms “first” and “second” in connection with the term “cooling zone section” distinguish between the two cooling zone sections 32, 34 of the cooling zone 30. The two sections 32, 34 may be arranged such that the rolling stock to be cooled (at least in its first pass through the cooling zone 30) is passed first through the first cooling zone section 32 and then through the second cooling zone section 34. Alternatively, the two cooling zone sections 32, 34 may be arranged so that the rolling stock (at least in its first pass through the cooling zone 30) is for example passed first through the second cooling zone section 34 and then through the first cooling zone section 32. The cooling system 2 may therefore be formed so that the second cooling zone section 34 is arranged before or after the first cooling zone section 32 in the running direction of the rolling stock.

(13) The cooling system 2 comprises a number of coolant supply lines 36 for supplying the cooling bars 8 with the coolant, wherein there is precisely one dedicated coolant supply line 36 is provided for each of the cooling bars 8.

(14) Each of the cooling bars 8 of the first cooling zone section 32 is connected by its dedicated coolant supply line 36 to the first distributor line 12 of the feed line system 9. In an analogous way, each of the cooling bars 8 of the second cooling zone section 34 is connected by way of its dedicated coolant supply line 36 to the second distributor line 16 of the feed line system 9. The cooling bars 8 of the first cooling zone section 32 are consequently supplied with the coolant 6 by the first distributor line 12, whereas the cooling bars 8 of the second cooling zone section 34 are supplied with the coolant 6 by the second distributor line 16.

(15) In each of the two cooling zone sections 32, 34, one half of the cooling bars 8 are configured to apply the coolant 6 to the rolling stock to be cooled from above, while the other half of the cooling bars 8 is configured to apply the coolant 6 to the rolling stock to be cooled from below.

(16) In the present exemplary embodiment, all of the cooling bars 8 of the second cooling zone section 34 are cooling bars of the same type of construction. These cooling bars 8 have nozzles, from which the coolant 6 leaves during the cooling operation of the cooling system 2. On the other hand, the cooling bars 8 of the first cooling zone section 32 differ from one another with regard to their type of construction. Thus, for example, some of the cooling bars 8 of the first cooling zone section 32 have coolant outlet pipes of a swan neck-like shape. In principle, all of the cooling bars 8 in the first cooling zone section 32 could also be of the same type of construction.

(17) A servicing flap valve 38 is arranged in each of the coolant supply lines 36. In addition, a shut-off member 40, which is formed as a continuously adjustable valve and serves for controlling a coolant flow through the respective coolant supply line 36, is arranged in each of the coolant supply lines 36.

(18) The cooling system 2 also comprises a scale channel 42, which is arranged underneath the cooling zone 30 and is intended for catching the coolant 6 coming out of the cooling bars 8 and for catching particles of scale. Furthermore, the cooling system 2 comprises a scale settling tank 44 for the deposition of particles of scale. The scale settling tank 44 is connected to the scale channel 42 by a discharge line 46, by way of which coolant 6 introduced into the scale channel 42 is directed into the scale settling tank 44 along with the particles of scale in it.

(19) The cooling system 2 also has a bypass line 48 and a shut-off member 50 arranged therein, which is formed as a continuously adjustable valve. The bypass line 48 is connected on the input side directly to a connection element 51 of the distributor line 16. The bypass line 48 opens out on the output side into the scale settling tank 44. The shut-off member 50 arranged in the bypass line 48 and the shut-off members 40 arranged in the coolant supply lines 36 also have at least substantially the same switching times.

(20) The second cooling zone section 34 of the cooling system 2 may optionally be operated in a laminar cooling mode, in a quasi laminar cooling mode or in an intensive cooling mode.

(21) In the laminar cooling mode, the coolant 6 is directed from the coolant reservoir 4 by way of the first main line 10 to the coolant supply lines 36 of the first cooling zone section 32 and to the coolant supply lines 36 of the second cooling zone section 34. The shut-off member 26 arranged in the connecting line 18 is in this case open, whereas the shut-off member 28 arranged in the second main line 14 is closed. The coolant pump 20 is switched off in this cooling mode.

(22) In the quasi laminar cooling mode and in the intensive cooling mode, the coolant 6 is directed from the coolant reservoir 4 by way of the first main line 10 to the coolant supply lines 36 of the first cooling zone section 32 and by way of the second main line 14 to the coolant supply lines 36 of the second cooling zone section 34. The shut-off member 26 arranged in the connecting line 18 is in this case closed, whereas the shut-off member 28 arranged in the second main line 14 is open.

(23) In the laminar cooling mode all of the coolant supply lines 36 of the cooling zone 30 are supplied with the coolant 6 by the first main line 10. In the quasi laminar cooling mode and in the intensive cooling mode, on the other hand, only the coolant supply lines 36 of the first cooling zone section 32 are supplied with the coolant 6 by the first main line 10, while the coolant supply lines 36 of the second cooling zone section 34 are supplied with the coolant 6 by the second main line 14.

(24) In the quasi laminar cooling mode, the coolant pump 20 is operated with a rotational speed at which a pressure drop in the coolant 6 that occurs as it flows through the coolant pump 20 is at least substantially compensated. On the other hand, in the intensive cooling mode, with the aid of the coolant pump 20, the coolant pressure in the second main line 14 is increased beyond the resultant pressure caused by the coolant reservoir 4.

(25) In each of the three cooling modes, the coolant is applied to the rolling stock both by cooling bars 8 of the first cooling zone section 32 and by cooling bars 8 of the second cooling zone section 34. The cooling bars 8 of the first cooling zone section 32 are in this case always supplied with the coolant 6 by the first main line 10 and not by the second main line 14.

(26) If there is a pause in rolling or if air is to be used (instead of the coolant) for cooling the rolling stock while the cooling system 2 is being operated in the intensive cooling mode, the coolant feed to the cooling bars 8 is interrupted with the aid of the shut-off members 40 arranged in the coolant supply lines 36. At the same time, the shut-off member 50 arranged in the bypass line 48 enables the bypass line 48.

(27) The coolant pump 20 is in this case not switched off, but is kept in operation in order to avoid later renewed start-up of the coolant pump 20. Its rotational speed is possibly reduced, in order to reduce the coolant flow through the second main line 14.

(28) A coolant flow from the second main line 14 is discharged by way of the bypass line 48, so that the coolant flow bypasses the coolant supply lines 36 of the second cooling zone section 34. Instead of flowing into the distributor lines 36, the coolant flow flows into the bypass line 48. By discharging the coolant flow by way of the bypass line 48, pressure surges in the present cooling system 2 are avoided, or at least reduced.

(29) In the present exemplary embodiment, the coolant flow is not discharged by the bypass line 48 directly from the second main line 14, but by way of the second distributor line 16 connected to the second main line 14. From the bypass line 48, the coolant flow is sent directly into the scale settling tank 44. From the scale settling tank 44, the coolant 6 therein can be transferred into the coolant reservoir 4 for further use, either directly or by way of a coolant treatment system (not represented in the figures).

(30) The descriptions of the following exemplary embodiments are in each case restricted primarily to the differences from the previous exemplary embodiment described in connection with FIG. 1, to which reference is made with respect to features and functions that remain the same. Elements that are substantially the same or correspond to one another are, where appropriate, denoted by the same reference signs and features that are not mentioned are included in the following exemplary embodiments without being described again.

(31) FIG. 2 shows another cooling system 2 for cooling hot-rolled rolling stock. In this exemplary embodiment, the bypass line 48 is connected on the output side directly to the coolant reservoir 4. Consequently, the coolant flow discharged from the second main line 14 by way of the bypass line 48 is sent from the bypass line 48 directly into the coolant reservoir 4 (instead of into the scale settling tank 44). There is no need here for any treatment of the coolant introduced into the coolant reservoir 4 by way of the bypass line 48.

(32) FIG. 3 shows a further cooling system 2 for cooling hot-rolled rolling stock. In this exemplary embodiment, the bypass line 48 is connected on the input side directly to a connection element 53 of the second main line 14. Correspondingly, in the present case, the coolant flow by way of the bypass line 48 is discharged directly from the second main line 14.

(33) Furthermore, the bypass line 48 is connected on the output side directly to the coolant reservoir 4. Consequently, in the present exemplary embodiment, the coolant flow discharged from the second main line 14 by sent from the bypass line 48 directly into the coolant reservoir 4 (instead of into the scale settling tank 44). There is no need here for any treatment of the coolant introduced into the coolant reservoir 4 by way of the bypass line 48.

(34) It is possible to dispense with switching off of the coolant pump 20 when there is an interruption of the coolant feed to the cooling bars 8.

(35) FIG. 4 shows yet another cooling system 2 for cooling hot-rolled rolling stock. In this exemplary embodiment, the bypass line 48 is connected on the input side directly to a connection element 53 of the second main line 14. Correspondingly, in the present case the coolant flow of the bypass line 48 is discharged directly from the second main line 14.

(36) Furthermore, the bypass line 48 is connected on the output side to a further connection element 55 of the second main line 14, wherein the first-mentioned connection element 53 of the second main line 14 is arranged downstream of the coolant pump 20 and the further connection element 55 of the second main line 14 is arranged upstream of the coolant pump 20.

(37) The coolant flow discharged from the second main line 14 by the bypass line 48 is sent back directly into the second main line from the bypass line 48 (instead of being sent into the scale settling tank 44). As long as the shut-off member 50 of the bypass line 48 is open and the shut-off members 40 of the coolant supply lines 36 of the second cooling zone section 34 are closed, the coolant pump 20 makes the coolant flow circulate in the bypass line 48 and in the second main line 14.

(38) FIG. 5 shows yet a further cooling system 2 for cooling hot-rolled rolling stock. The cooling system 2 comprises an additional bypass line 52 with a shut-off member 54, which is formed as a continuously adjustable valve. This bypass line 52 is connected on the input side directly to a connection element 53 of the second main line 14. On the output side, this bypass line 52 is connected directly to the coolant reservoir 4.

(39) A further coolant flow is discharged by the additional bypass line 52 from the second main line 14, wherein the further coolant flow is sent from the additional bypass line 52 directly into the coolant reservoir 4.

(40) In order to effectively avoid a pressure surge when there is an interruption of the coolant feed to the cooling bars 8, first the shut-off member 50 of the first bypass line 50 is opened. After that, the shut-off member 54 of the additional bypass line 52 is slowly opened and, in return, the shut-off member 50 of the first-mentioned bypass line 48 is closed again, in order that no further coolant is introduced into the scale settling tank 44. Return of the coolant previously introduced into the scale settling tank 44 and then into the coolant reservoir 4 involves a higher energy expenditure than a direct return of the coolant from the second main line 14 into the coolant reservoir 4.

(41) A combination of a number of bypass lines is also possible in the case of the exemplary embodiments from FIG. 1 to FIG. 4. In particular, in the exemplary embodiments from FIG. 1 to FIG. 3, in addition to the bypass line 48 respectively disclosed there, a bypass line 48 as in FIG. 1 may be provided.

(42) Although the invention has been illustrated more specifically and described in detail by the preferred exemplary embodiments, the invention is not restricted by the examples disclosed and other variations may be derived therefrom without departing from the scope of protection of the invention.

List of Designations

(43) 2 Cooling system 4 Coolant reservoir 6 Coolant 8 Cooling bars 9 Feed line system 10 Main line 12 Distributor line 14 Main line 16 Distributor line 18 Connecting line 20 Coolant pump 22 Servicing flap valve 24 Servicing flap valve 26 Shut-off member 28 Shut-off member 30 Cooling zone 32 Cooling zone section 34 Cooling zone section 36 Supply line 38 Servicing flap valve 40 Shut-off member 42 Scale channel 44 Scale settling tank 46 Discharge line 48 Bypass line 50 Shut-off member 51 Connection element 52 Bypass line 53 Connection element 54 Shut-off member 55 Connection element