EP2892664B1 - Method and device for dynamically supplying coolant to a cooling device for cooling metal strip or other rolled stock - Google Patents

Description

Field of the invention

The present invention is directed to a method and apparatus for dynamically supplying a cooling device for cooling metal strip or other rolling stock with coolant. The cooling device may in particular comprise one or more spray bars.

State of the art

A variety of systems for providing cooling water from a high tank for laminar or pressure cooling in hot rolling mills is already known from the prior art. Considerable amounts of cooling water are needed to cool hot rolling stock, to adequately define and rapidly cool the strip, depending on the requirements of the finished product. The amounts of water needed to reach a given cooling rate are often on the order of hundreds or even thousands of cubic meters per hour. These extraordinarily large amounts of water are passed, for example, via ducts throttled by valves from a high tank to the spray bars.

Such a system according to the prior art is exemplary in the FIG. 1 shown. The stored in the high tank 4 water is supplied via lines 2 a central manifold 6. From this common distributor 6, the water is supplied to the individual spray bars 1 via further lines. However, this known arrangement has some disadvantages. For modern metal alloys or steels, large cooling rates must also be as precisely adjustable or controllable as possible. However, this is made more difficult by the very large amounts of water used. In particular, on and off operations can not be carried out satisfactorily fast by existing concepts, which usually include control valves, creating a switch-on of the Cooling often takes more than 10 seconds to reach the desired cooling rate. However, since the rolling stock in many cases with several meters per second moves through the system, a large strip length is not cooled at the desired cooling rate, resulting in quality losses of this band section result.

Another disadvantage is the high forces that act on switching operations of cooling on the piping systems or cooling systems. In particular, there is a risk in rapid switching operations of the cooling water supply that strong pressure surges damage the cooling system. Such pressure peaks can even lead to failure of the cooling system and thus the entire rolling mill.

The WO 2012/011578 A1 discloses a device for cooling a metal strip according to the preamble of claim 5 and a method for cooling a metal strip according to the preamble of claim 1. The cooling device comprises a plurality of directed onto the metal strip spray nozzle groups, which are arranged in a common housing and at least one Supply line to be supplied with coolant.

In view of the described prior art, the technical object of the invention is to provide an improved coolant supply, which in particular avoids or at least significantly reduces pressure surges during switch-on processes. Furthermore, the technical task may be to achieve a desired cooling rate faster than before in order to optimally supply a rolled strip with coolant.

Disclosure of the invention

The asked technical problem is solved by the features of the method for dynamic supply of a cooling device, in particular of at least one spray bar, for cooling metal strip or other rolling stock with coolant according to claim 1. The method comprises at least the steps of providing a pre-accelerated or flowing coolant flow, wherein the coolant flow bypasses the cooling device and is guided into a return, as well as monitoring the presence and / or the temperature of a metal strip or other rolling stock to be cooled. According to the invention, the pre-accelerated coolant flow to the cooling device is dependent on the presence and / or the temperature of the metal strip or Coolant solved according to claim 1. The method comprises at least the steps of providing a pre-accelerated or flowing coolant flow, wherein the coolant flow bypasses the cooling device and is guided into a return, as well as monitoring the presence and / or the temperature of a metal strip or other rolling stock to be cooled. According to the invention, the pre-accelerated coolant flow is diverted to the cooling device in dependence on the presence and / or temperature of the metal strip or other rolling stock, the coolant flow being bypassed and guided into a return instead of the cooling device, the cooling device for cooling the metal strip or the other rolling stock is supplied pre-accelerated.

By pre-acceleration of the coolant and the diverting or redirecting this vorbeschleunigten coolant flow acting on the system components pressure surges can be avoided or significantly reduced. Furthermore, the reaction time of the cooling improves significantly. The deflection can be done much faster than the process of accelerating a remote, stagnant amount of water. In addition, a desired cooling rate can be achieved or adjusted faster and more precisely. In general, the adjustability of the volume flows used is thus improved.

According to a preferred embodiment, the pressure loss of the pre-accelerated coolant flow when bypassing the cooling device and the pressure loss when supplying the pre-accelerated coolant flow to the cooling device are less than 50%, preferably less than 20% or even less than 10%. Preferably, both values are substantially the same. Thus, by diverting the coolant flow, pressure surges of the coolant flow when the coolant flow is diverted to supply it to the cooling device are avoided. In other words, the flow resistance for the coolant flow at bypass or line is substantially equal to or different from the cooling device as stated above.

The redirecting operation preferably takes place in less than 5 seconds or even less than 1.5 seconds. Especially with such relatively short switching times, the inventive method is of particular advantage.

According to a preferred embodiment, the deflection of the coolant flow is less than 5 m, preferably less than 1 m upstream of the cooling device (1) (so that the path of the coolant flow between the location of the deflection (5) and the outlets (7) of the cooling device (1). is kept as low as possible to cool the belt).

According to a further preferred embodiment, the volume flow of the coolant or coolant flow to be deflected is more than 150 m ³ / h and preferably more than 400 m ³ / h. Especially in view of such large volume flows, the present invention is particularly advantageous.

Furthermore, the invention is also directed to a device for cooling a metal strip, preferably for carrying out the method according to one of the preceding claims. The apparatus initially comprises a cooling device for cooling metal strip or other rolling stock, which comprises at least one spray bar with coolant outlets for dispensing the coolant onto the metal strip. Further, the apparatus includes conduit means for directing a flow of coolant from a source of coolant to the spray bar, and bypass means for directing the flow of refrigerant from the conduit means into a return line. Switchable diverting means of the apparatus are adapted to switchably direct the flow of refrigerant through the conduit means to the spray bar or to divert the flow of refrigerant from the conduit means into the bypass means.

The advantages of the device essentially correspond to those of the method already described.

In a preferred embodiment, the device may comprise at least one valve for adjusting a volumetric flow of the coolant flow (flowing) through the conduit means, the diverting means being located downstream of the control valve.

In a further preferred embodiment, the switchable bypass means may each comprise at least one switchable flap for directing the coolant flow to the spray bars or into the bypass means.

In a further preferred embodiment, the conduit means further comprises a pump for increasing the volumetric flow provided by the source. By means of such a pump, an even more pre-accelerated volume flow can be provided.

In a further preferred embodiment, the pump can be bypassed by means of a bypass through the coolant flow. Such an arrangement allows cooling with the coolant pressure available without any pump. The water pressure can be provided by a high tank, for example.

Overall, it is thus possible to provide very small volume flows (eg laminar operation) and also very large volume flows (pressure operation by means of a pump).

In a further preferred embodiment, a plurality of spray bars, preferably a maximum of ten spray bars, are combined to form a first cooling group, wherein the first cooling group can be supplied with coolant via first conduit means and at most three of the spray bars of the first Cooling group switchable bypass means are provided for directing the flow of coolant from the first conduit means in a return, so that the coolant flow of at most three spray bars of the first cooling group is separated from the remaining spray bars of the first cooling group in the bypass means or in the return flow.

In a further preferred embodiment, a plurality of further spray bars, preferably a maximum of ten further spray bars, combined to form a second cooling group, wherein the second cooling group is supplied via second conduit coolant and at each of at least three of the spray bars of the second cooling group switchable bypass means for directing the flow of coolant from the second line means are provided in a return, so that the coolant flow of at most three spray bars of the second cooling group is separated from the remaining spray bars of the second cooling group in the bypass means or in the return flow.

In a further preferred embodiment, the first and the second cooling group are fed or supplied separately by the source with coolant.

In a further preferred embodiment, the volume flow to each individual cooling group can be increased separately by a pump.

In a further preferred embodiment, the device comprises a plurality of spray bars, wherein each spray bar is assigned a switchable diverting means separately from the further spray bars, so that either the pre-accelerated coolant flow can be fed to each spray bar via the conduit means or the coolant flow can be supplied to the bypass means via the diverting means assigned to the spray bar.

In a further preferred embodiment, at least one of the spray bars is supported by a support device and the switchable diverting means is mounted on this support means. Alternatively or additionally, the switchable diverting means is arranged less than 5 m, preferably less than 3 m, upstream of the spray bar.

All features of the embodiments described above can be combined with each other or replaced.

Brief description of the figures

Figur 1

(Stand der Technik) eine Vorrichtung zur Versorgung mehrerer Spritzbalken mit Kühlmittel;

Figur 2

eine schematische Darstellung eines erfindungsgemäßen Ausführungsbeispiels einer Vorrichtung zur Kühlung von Metallband oder sonstigem Walzgut; und

Figur 3

eine schematische Darstellung eines weiteren erfindungsgemäßen Ausführungsbeispiels einer Vorrichtung zur Kühlung von Metallband oder sonstigem Walzgut.

The figures of the embodiments will be briefly described below. Further details can be found in the detailed description of the embodiments. Show it:

FIG. 1

(Prior Art) a device for supplying a plurality of spray bars with coolant;

FIG. 2

a schematic representation of an embodiment according to the invention of a device for cooling metal strip or other rolling stock; and

FIG. 3

a schematic representation of another embodiment of the invention an apparatus for cooling metal strip or other rolling stock.

Detailed description of the embodiments

For the sake of clarity, reference will first be made to the FIG. 1 disclosed prior art. Pictured is a high tank 4, which serves as storage for coolant. Via lines, the coolant is usually a distributor 6 and a manifold 6 can be fed. From this distributor 6, the coolant can be supplied to a plurality of spray bars 1. In this case, the spray bars 1 for applying a metal strip with the coolant in each case a plurality of outlets 7. As shown, between the manifold 6 and the respective spray bar 1, a transducer 15 (for example, for coolant pressure or volume flow), a control valve 9 or a Stopcock 8 may be arranged. Through these elements, the guided to the respective spray bar 1 coolant flow can monitor and adjust.

The FIG. 2 shows a schematic of an embodiment of the invention. Coolant is similar to the prior art according to the FIG. 1 provided by a memory 4. In contrast to the arrangement according to FIG. 1 includes the embodiment of the invention the FIG. 2 However, preferably no distributor 6. Rather, each spray bar 1 is fed separately via a line 2 coolant from the memory 4. The provided coolant flow can be increased by a pump 11, 11 'or booster pump 11, 11'. In addition, this pump 11, 11 'for the coolant flow, for example, by a bypass 13 can be bypassed. This bypass 13 may be designed to be switchable so that the coolant flow either through the pump 11, 11 'is promoted or the pump 11, 11' bypasses and is passed only by the (static) pressure of the memory 4 through the conduit system 2. The volume flow can also be monitored by a measuring transducer 15 and / or be adjustable by a control valve 9. However, the specific regulation of the volume flow is not core of the invention and can be done for example by already known control engineering measures. It is crucial that the device according to the invention has switchable deflection means 5 which can redirect a pre-accelerated coolant flow away from the spray bar 1. For example, a flowing or pre-accelerated volumetric flow can first be conducted into an overflow or overflow 3. Such a coolant flow may, for example, subsequently follow the reservoir 4 to be led back. A further treatment of the coolant is eliminated, since the coolant is not polluted when diverted by the means 5. The deflection means 5 may generally comprise two switchable shut-off valves or valves, so that a volume flow is supplied to either the spray bar 1 or the return 3. However, it is also an arrangement with only one switchable flap possible. By the described arrangement, an already pre-accelerated coolant flow can be provided, which can be supplied to the spray bar 1 by the deflection means 5 as required. The means 5 can be switched, for example, by means of a sensor which registers the presence or the entry or exit of a band. Alternatively or additionally, the temperature of the belt can be monitored with a temperature sensor. Depending on the temperature as a control variable, the deflection means 5 (actuator) can thus preferably be switched or set in order to adjust the inflow of the coolant (control variable) via the spray bars 1 and their outlets 7 to the belt.

The FIG. 3 discloses a schematic of a cooling device according to another embodiment of the invention. Unlike in the FIG. 1 As shown, several spray bars 1 are combined to form a first cooling group 10 and further spray bars 1 'are combined to form a second cooling group 10'. Within each of the groups 10, 10 ', a deflecting device 50', 50 is associated with each individual spray bar 1, 1 '(upstream). That is, each spraying bar 1, 1 'can be supplied with a volume flow pre-accelerated by an associated deflecting means 50, 50'. The deflecting means 50, 50 'are preferably located as close as possible to the spray bar 1, 1' to be supplied, in order to minimize the time needed for the distance between the location of the deflection by the means 5 and the spray bar, whereby the reaction speed or the controllability of the system is significantly improved.

The deflection means 5, 50, 50 'can generally be switched, for example, electrically, pneumatically or hydraulically.

Above all, the embodiments described above serve to better understand the invention and should not be understood as limiting. The scope of protection of the present patent application results from the patent claims.

The features of the described embodiments can be combined or replaced with each other.

Furthermore, the features described can be adapted by the skilled person to existing circumstances or existing requirements.

LIST OF REFERENCE NUMBERS

1

spray bars

1'

spray bars

2

conduit means

3

Bypass / return

4

Source / high tank

5

switchable deflection / switch fitting

6

manifold

7

Radiator outlets from spray bars

8th

stopcock

9

control valve

10

first cooling group

10 '

second cooling group

11

Pump / booster pump

11 '

second pump

13

bypass

15

Transducers

20

first conduit means

20 '

second conduit means

50

first switchable deflection means

50 '

second switchable deflection means

Claims (15)

1. Method of dynamically supplying a cooling device (1, 1'), in particular at least one spray bar (1, 1'), for cooling metal strip or other rolling stock with coolant,
   characterised in that the method comprises the following steps:

   a) providing a pre-accelerated coolant flow, wherein the coolant flow bypasses the cooling device (1, 1') and is conducted to a return (3);

   b) monitoring the presence and/or temperature of a metal strip to be cooled or other rolling stock; and

   c) diverting the already pre-accelerated coolant flow to the cooling device (1, 1') depending on the presence and/or a defined temperature of the metal strip or other rolling stock so that the coolant flow instead of bypassing the cooling device and being conducted to the return is fed, already pre-accelerated, to the cooling device (1, 1') for cooling the metal strip or other rolling stock.
2. Method according to claim 1, wherein the pressure loss of the coolant flow when bypassing the cooling device (1, 1') and the pressure loss when feeding the coolant flow to the cooling device (1) differ from one another by less than 20% or are substantially the same so that pressure surges when diversion of already pre-accelerated coolant flow to the cooling device (1, 1') takes place are avoided.
3. Method according to claim 1 or 2, wherein for minimising the path between the place of diversion of the coolant flow and outlets of the cooling device (1, 1') the diversion of the coolant flow takes place at less than 5 metres, preferably at less than 3 metres, upstream of the outlets of the cooling device (1, 1').
4. Method according to one of the preceding claims, wherein the volume flow of the coolant to be diverted is more than 150 m³/h and preferably more than 400 m³/h.
5. A device for cooling a metal strip, preferably for carrying out the method according to any one of the preceding claims, comprising:

   a cooling device for cooling metal strip or other rolling stock, which comprises at least one spray bar (1, 1') with coolant outlets for delivering the coolant to the metal strip; and

   duct means (2, 20, 20') for conducting a coolant flow from a coolant source (4) to the spray bar (1, 1');

   characterised in that the device further comprises the following:

   bypass means for conducting the coolant flow from the duct means (2, 20, 20') to a return (3); and

   switchable diverting means (5, 50, 50') constructed for switchable conducting of the coolant flow through the duct means (2, 20, 20') to the spray bar (1, 1') or diversion of the coolant flow from the duct means (2, 20, 20') to the bypass means.
6. Device according to claim 5, wherein the device comprises at least one valve (9) for regulating a volume flow of the coolant flow flowing through the duct means, wherein the diverting means (5, 50, 50') are arranged downstream of the regulating valve (9).
7. Device according to claim 5 or 6, wherein the switchable diverting means (5, 50, 50') comprises at least one switchable flap for conducting the coolant flow to the spray bars (1) or to the bypass means and/or wherein the switchable diverting means (5, 50, 50') carries out a switching process in less than 5 seconds, preferably in less than 1.5 seconds.
8. Device according to any one of claims 5 to 7, wherein the duct means (2, 20, 20') further comprise a pump (11, 11') for increasing the volume flow of coolant provided by the source.
9. Device according to claim 8, wherein the pump (11, 11') can be bypassed by the coolant flow by means of a bypass (13).
10. Device according to any one of claims 5 to 9, wherein a plurality of spray bars (1), preferably a maximum of ten spray bars (1), is assembled to form a first cooling group (10) and coolant can be fed to the first cooling group (10) by way of first duct means (20) and switchable diverting means (50) for conducting the coolant flow from the first duct means (20) to a return are provided for at most three of the spray bars (1) of the first cooling group (10), so that the coolant flow from the at most three spray bars (1) of the first cooling group (10) can be diverted to the bypass means independently of the remaining spray bars of the first cooling group (10).
11. Device according to claim 10, wherein in addition a plurality of further spray bars (1'), preferably a maximum of ten further spray bars (1'), is assembled to form a second cooling group (10') and coolant can be fed to the second cooling group (10) by way of second duct means (20') and switchable diverting means (50) for conducting the coolant flow from the second duct means (20') to a return are provided for at most three of the spray bars (1') of the second cooling group (10'), so that the coolant flow from the at most three spray bars (1') of the second cooling group (10') can be diverted to the bypass means independently of the remaining spray bars (1') of the second cooling group (10').
12. Device according to claim 1, wherein the first and second cooling groups (10, 10') can be supplied with coolant by the source (4) separately from one another.
13. Device according to claim 11 or 12, wherein the volume flow to each individual cooling group (10, 10') can be separately increased each time by a pump (11, 11').
14. Device according to any one of claims 5 to 9, wherein the device comprises a plurality of spray bars (1), and a switchable diverting means (5) is associated with a maximum of three of the spray bars (1) separately from the further spray bars (1) so that either the pre-accelerated coolant flow can be fed via the duct means (2) to the maximum of three spray bars (1) or the coolant flow can be fed to the bypass means by way of the diverting means (5) associated with the maximum of three spray bars (1); or, in particular, a switchable diverting means (5) is associated with each of the spray bars (1) separately from the further spray bars (1) so that either the pre-accelerated coolant flow can be fed to each spray bar (1) by way of the duct means (2) or the coolant flow can be fed to the bypass means by way of the diverting means (5) associated with the spray bar (1).
15. Device according to any one of claims 5 to 14, wherein at least one of the spray bars (1) is supported by a support device and the switchable diverting means (5) is mounted on this support device and/or wherein the switchable diverting means (5) is located less than 5 metres upstream of the spray bar (1).

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