DE102021001967A1 - Pressure surge-free coupling and decoupling of pumps - Google Patents

Abstract

A cooling device (1) has application devices (4) by means of which water (5) is applied to a hot rolling stock (2) made of metal. The application devices (4) are preceded by a pump arrangement (6) with several pumps (8) connected in parallel, by means of which the water (5) is pumped via a collecting line (7) to the application devices (4). The total amount of water (W) fed into the collecting line (7) by the pumps (8) is equal to the sum of the individual amounts of water (wi) pumped by each individual pump (8). A target total water quantity (W*) and a target pressure (p*) on the outlet side of the pump arrangement (6) are known to a control device (11) of the cooling device (1). It determines the target individual water quantities (wi*) for the pumps (8), so that their total is equal to the target total water quantity (W*). It determines the respective speed (ni) for the pumps (8) on the basis of the respective target individual water quantity (wi*) and the target pressure (p*) and controls the pumps (8) accordingly. To decouple a pump (81) from the pump arrangement, a time profile of its target individual water quantity (w1*) is determined for this pump (81) in such a way that this target individual water quantity (w1*) changes from an initial value during a decoupling time (T1). (w10*) falls to a final value of 0. The control device (11) determines the desired individual water quantity (w1*) for the pump (81) to be decoupled during the decoupling time (T1) according to the course over time. The procedure for coupling a pump (84) into the pump arrangement (6) is reversed.

Description

field of technology

• - wobei die Kühleinrichtung eine Anzahl von Aufbringeinrichtungen aufweist, mittels derer Wasser auf das Walzgut aufgebracht wird,
• - wobei den Aufbringeinrichtungen eine Pumpenanordnung vorgeordnet ist, mittels derer das Wasser über eine Sammelleitung zu den Aufbringeinrichtungen gepumpt wird,
• - wobei die Pumpenanordnung mehrere parallel geschaltete Pumpen aufweist, so dass eine von den Pumpen in die Sammelleitung eingespeiste Gesamtwassermenge gleich der Summe von Einzelwassermengen ist, die von jeweils einer einzelnen Pumpe gepumpt werden,

mit folgenden, zyklisch ausgeführten Schritten:

• - der Steuereinrichtung werden eine Soll-Gesamtwassermenge und ein Soll-Druck ausgangsseitig der Pumpenanordnung bekannt,
• - die Steuereinrichtung bestimmt für die Pumpen eine jeweilige Soll-Einzelwassermenge, so dass die Summe der Soll-Einzelwassermengen gleich der Soll-Gesamtwassermenge ist,
• - die Steuereinrichtung ermittelt für die Pumpen anhand der jeweiligen Soll-Einzelwassermenge und des Soll-Druckes die jeweilige Drehzahl,
• - die Steuereinrichtung steuert die Pumpen entsprechend der jeweils ermittelten Drehzahl an.

The present invention is based on an operating method for a cooling device for cooling a hot rolling stock made of metal,

• - wherein the cooling device has a number of application devices, by means of which water is applied to the rolling stock,
• - wherein the application devices are preceded by a pump arrangement, by means of which the water is pumped via a collecting line to the application devices,
• - wherein the pump arrangement has a plurality of pumps connected in parallel, so that a total amount of water fed into the collecting line by the pumps is equal to the sum of individual amounts of water that are pumped by a single pump in each case,

with the following cyclically executed steps:

• - the control device is informed of a target total water quantity and a target pressure on the output side of the pump arrangement,
• - the control device determines a respective target individual water quantity for the pumps, so that the sum of the target individual water quantities is equal to the target total water quantity,
• - the control device determines the respective speed for the pumps based on the respective target individual water quantity and the target pressure,
• - The control device controls the pumps according to the speed determined in each case.

• - der Steuereinrichtung eine Soll-Gesamtwassermenge und ein Soll-Druck ausgangsseitig der Pumpenanordnung bekannt werden,
• - die Steuereinrichtung für die Pumpen eine jeweilige Soll-Einzelwassermenge bestimmt, so dass die Summe der Soll-Einzelwassermengen gleich der Soll-Gesamtwassermenge ist,
• - die Steuereinrichtung für die Pumpen anhand der jeweiligen Soll-Einzelwassermenge und des Soll-Druckes die jeweilige Drehzahl ermittelt und
• - die Steuereinrichtung die Pumpen entsprechend der jeweils ermittelten Drehzahl ansteuert.

The present invention is also based on a computer program that includes machine code that can be processed by a control device for a cooling device for cooling a hot rolling stock made of metal, the processing of the machine code by the control device having the effect that

• - the control device becomes aware of a target total water quantity and a target pressure on the output side of the pump arrangement,
• - the control device for the pumps determines a respective target individual water quantity, so that the sum of the target individual water quantities is equal to the target total water quantity,
• - The control device for the pumps determines the respective speed based on the respective target individual water quantity and the target pressure and
• - The control device activates the pumps according to the speed determined in each case.

• - wobei die Kühleinrichtung eine Anzahl von Aufbringeinrichtungen aufweist, mittels derer Wasser auf das Walzgut aufgebracht wird,
• - wobei den Aufbringeinrichtungen eine Pumpenanordnung vorgeordnet ist, mittels derer das Wasser über eine Sammelleitung zu den Aufbringeinrichtungen gepumpt wird,
• - wobei die Pumpenanordnung mehrere parallel geschaltete Pumpen aufweist, so dass eine von den Pumpen in die Sammelleitung eingespeiste Gesamtwassermenge gleich der Summe von Einzelwassermengen ist, die von jeweils einer einzelnen Pumpe gepumpt werden,
• - wobei die Kühleinrichtung eine derartige Steuereinrichtung aufweist, welche die Kühleinrichtung gemäß einem derartigen Betriebsverfahren betreibt.

The present invention is also based on a cooling device for cooling a hot rolling stock made of metal,

• - wherein the cooling device has a number of application devices, by means of which water is applied to the rolling stock,
• - wherein the application devices are preceded by a pump arrangement, by means of which the water is pumped via a collecting line to the application devices,
• - wherein the pump arrangement has a plurality of pumps connected in parallel, so that a total amount of water fed into the collecting line by the pumps is equal to the sum of individual amounts of water that are pumped by a single pump in each case,
• - wherein the cooling device has such a control device, which operates the cooling device according to such an operating method.

State of the art

In many cases, the rolling stock is actively cooled with water before, during and/or after rolling metal stock. The cooling can take place, for example, in a cooling section that is downstream of a hot rolling train. It can also take place by means of interstand cooling, which is arranged between the roll stands of a hot rolling train. It can also take place in a cooling system that is arranged between a roughing train and a finishing train.

The water is applied to the rolling stock by appropriate application devices, for example cooling bars or spray bars. The water is fed to the application devices from a collecting line via branch lines in which valves are arranged. The collection line, in turn, is fed via pumps. In particular, so-called intensive cooling systems are constructed in this way. However, such procedures are also known for laminar cooling.

Configurations are known in which no buffer reservoirs for the water are arranged between the pump arrangement and the application devices or the associated valves. In this case, the total amount of water fed into the collecting line by the pump arrangement corresponds directly to the amount of water applied to the rolling stock via the application devices. In other cases, to the Sam duct and/or the branch lines are connected to buffer storage, for example an elevated tank or expansion tanks filled partly with water and partly with air. It is also known to provide risers with an overflow. Which of the procedures mentioned is taken is of secondary importance within the scope of the present invention. The only decisive factor is that there are several pumps arranged in parallel.

With such a pump arrangement, it does not always make sense to use all of the pumps. For example, it may be necessary to stop a pump for maintenance or because of an unforeseen defect. The situation can also arise in which, due to the current operating state of the cooling device, simultaneous operation of all pumps is technically possible, but is economically disadvantageous. However, switching pumps on and off is problematic. In particular, not only is a certain amount of time required, but unnecessary wear and tear often occurs in the mechanics, the valves, the pumps, etc., since so-called pressure surges can occur, i.e. abrupt pressure changes, especially when switching off - sometimes also when switching on.

In order to avoid pressure surges, it is known to arrange check valves on the outlet side of the pump. This prevents water from flowing backwards through the respective pump. When a respective pump is switched off, the corresponding non-return valve closes. The non-return valves are equipped with damping elements that reduce the pressure surge that inevitably occurs when the non-return valve closes quickly if the relevant pump is switched off quickly. This approach has several key disadvantages. On the one hand, the damping elements are complex, expensive and prone to failure. Furthermore, when the pumps are switched on, the non-return valves always cause a flow resistance, which makes the control less precise. Finally, check valves are also more expensive than normal switching valves.

It is also known to slowly reduce the speed of a pump that is to be switched off. The associated non-return valve then closes slowly and smoothly. Although this procedure avoids the damping elements, check valves are still required.

Furthermore, it is known to use a sequential switch-off strategy. Such a sequential switch-off strategy is necessary in particular when only normal switching valves are arranged on the output side of the pumps. However, it can also be used if check valves are present. As part of the sequential shutdown strategy, for example, all of the pumps in the pump arrangement that are in operation are first shut down to a specific speed. The speed is determined in such a way that it is possible to switch off a pump without any problems. Then the switching valve is closed at the pump to be switched off. Then the pump is switched off. Finally, the remaining pumps in the pump arrangement—that is, without the pump that has been switched off—are run up to operating speed again and the control of the cooling section is continued. This procedure has the disadvantage that normal operation of the cooling device is not possible during the switch-off period.

Furthermore, it is known to shift the switching off of pumps to periods during which only little water is required and the speeds of the pumps are therefore relatively low. This approach is very inflexible. This applies even more when a short break in production has to be planned to switch off a pump.

Inverse procedures are known for switching on a pump. If a check valve is present, the pump can be run up to its target speed directly. In this case, it pushes the check valve open as soon as it generates a sufficiently high pump pressure. If there is no check valve, a switch-on strategy that is the inverse of the switch-off strategy explained above is implemented.

In many cases, at least a short-term impairment of production cannot be avoided when a pump is switched on or off. Only in the variant, which is disadvantageous for other reasons, in which the water is first pumped into a buffer storage tank, is the decoupling so good that pumps can be switched on or off during production without any problems. With a sufficiently large buffer store, the time for switching on and off is also only of minor importance, so that the switch-off strategy and the switch-on strategy can be implemented without any problems. In this case, however, a correspondingly large buffer memory is required. In all other cases, a pump can only be switched on or off if the quantity of rolled stock to be cooled is reduced at the same time or less precise cooling with the associated loss of quality of the rolled stock is accepted.

It is known that in the case of pumps, the speed, the pumped water volume and the pressure increase (i.e. the difference between the pump pressure prevailing on the outlet side of the pump and the suction pressure prevailing on the inlet side of the pump) can be described by a pump characteristic, for example in the form of a two-dimensional family of characteristics or by a parameterizable one-dimensional characteristic. Purely as an example, for the two-dimensional family of characteristics on the WO 2013/143 925 A1 and for the one-dimensional parameterizable characteristic on the older EP application, which was not pre-published on the filing date 20 169 308.2 (Registration date April 14, 2020). In particular, the corresponding two-dimensional family of characteristics is often published by the manufacturer of the respective pump as part of the data sheet.

From the WO 2019/115 145 A1 It is known that when determining the required pump pressure, in addition to the amount of water to be pumped, changes in the amount of water and the corresponding acceleration of the water must also be taken into account.

Summary of the Invention

The object of the present invention is to create possibilities by means of which a pump can be switched on or off in a relatively simple and reliable manner without negatively influencing the ongoing operation of the cooling device.

As far as the decoupling of a pump from the pump arrangement is concerned, the object is achieved by an operating method having the features of claim 1 . According to the invention, an operating method of the type mentioned at the outset is designed in that, for decoupling a pump from the pump arrangement, a time profile of the target individual water quantity for the pump to be decoupled is determined in such a way that the target individual water quantity of the pump to be decoupled increases from an initial value during a decoupling time drops from 0 to a final value of 0, and that the control device determines the target individual water quantity for the pump to be decoupled during the decoupling time according to the course over time.

As far as the coupling of a pump into the pump arrangement is concerned, the object is achieved by an operating method having the features of claim 2 . According to the invention, an operating method of the type mentioned at the outset is designed in that, for coupling a pump into the pump arrangement, a time profile of the pump to be coupled in is determined for the pump to be coupled in such that the target individual water quantity of the pump to be coupled in during a coupling time varies from an initial value of 0 rises to a final value above 0, and that the control device determines the target individual water quantity for the pump to be coupled in during the coupling time according to the course over time.

The two methods can also be combined with one another, so that on the one hand a pump is coupled into the pump arrangement and on the other hand another pump that is different from the pump to be coupled is decoupled from the pump arrangement. In the simplest case, a pump is coupled into the pump arrangement and another pump is decoupled from the pump arrangement one after the other. In this case, the associated time curves of the corresponding target individual water quantities do not overlap in time. The order is therefore irrelevant. However, it is also possible for the time profile of the target individual water quantity for the pump to be coupled in and the time profile of the target individual water quantity for the pump to be coupled out (or the coupling time and the decoupling time) to overlap in time. In this case, the coupling and the decoupling take place at least partially simultaneously. In this case, too, the order is irrelevant.

• - die Soll-Einzelwassermenge für eine aus der Pumpenanordnung auszukoppelnde Pumpe während einer Auskoppelzeit gemäß einem zeitlichen Verlauf von deren Soll-Einzelwassermenge bestimmt, wobei der zeitliche Verlauf während der Auskoppelzeit von einem Anfangswert oberhalb von 0 auf einen Endwert von 0 absinkt, und/oder
• - die Soll-Einzelwassermenge für eine in die Pumpenanordnung einzukoppelnde Pumpe während einer Einkoppelzeit gemäß einem zeitlichen Verlauf von deren Soll-Einzelwassermenge bestimmt, wobei der zeitliche Verlauf während der Einkoppelzeit von einem Anfangswert von 0 auf einen Endwert oberhalb von 0 ansteigt.

The object is also achieved by a computer program with the features of claim 5. According to the invention, the processing of the computer program causes, in addition to the steps mentioned above, that the control device

• - the target individual water quantity for a pump to be decoupled from the pump arrangement is determined during a decoupling time according to a time profile of its target individual water quantity, with the time profile falling from an initial value above 0 to a final value of 0 during the decoupling time, and/or
• - Determines the target individual water quantity for a pump to be coupled into the pump arrangement during a coupling time according to a time profile of its target individual water quantity, with the time profile increasing from an initial value of 0 to a final value above 0 during the coupling time.

The object is further achieved by a control device for a cooling device for cooling a hot rolling stock made of metal with the features of claim 6. According to the invention, the control device is programmed with a computer program according to the invention, so that the Controller operates the cooling device according to an operating method according to the invention.

The object is also achieved by a cooling device for cooling a hot rolling stock made of metal with the features of claim 7. According to the invention, the cooling device has a control device according to the invention, which operates the cooling device according to an operating method according to the invention.

character list

• 1 eine Kühleinrichtung,
• 2 ein Ablaufdiagramm und
• 3 bis 5 Zeitdiagramme.

The characteristics, features and advantages of this invention described above, and the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings. This shows in a schematic representation:

• 1 a cooling device,
• 2 a flow chart and
• 3 until 5 timing charts.

Description of the embodiments

According to 1 A cooling device 1 for cooling a hot rolling stock 2 made of metal is arranged downstream of a rolling train. From the rolling mill is in 1 only the last roll stand 3 is shown. If required, the rolling train can also have further roll stands, which are arranged upstream of the last roll stand 2 . Due to the downstream arrangement of the cooling device 1, the cooling device 1 is designed as a cooling section. But this is of secondary importance. The cooling device 1 could also be arranged inside the rolling mill or upstream of the rolling mill. The rolling stock 2 can be a flat rolling stock or another type of rolling stock, for example a rod-shaped rolling stock or a profile. The material of the rolling stock 2 can be steel or aluminum, for example. The shape and material of the rolling stock 2 are also of secondary importance.

The cooling device 1 has a number of application devices 4 by means of which water 5 is applied to the rolling stock 2 . Specifically are in 1 Four application devices 4 are shown, by means of which the water 5 is applied to the rolling stock 2 exclusively from above. Both the number of application devices 4 and their arrangement (in the case of a flat rolling stock 2 above and/or below the rolling stock 2, in the case of another rolling stock 2 at any point on the circumference around the rolling stock 2) are within the scope of the present invention of secondary importance.

A pump arrangement 6 is arranged upstream of the application devices 4 . The water 5 is pumped to the application devices 4 via a collecting line 7 by means of the pump arrangement 6 . The pump arrangement 6 has a plurality of pumps 8 connected in parallel. The exact number of pumps 8 is of secondary importance. However, at least two pumps 8 are present. The number of pumps 8 is usually considerably greater than two and is four to ten, for example. The number of pumps 8 is referred to below as k. The pumps 8 are generally designed and dimensioned identically to one another. However, this is not absolutely necessary. The pumps 8 pump a respective individual amount of water wi (with i=1, 2, . . . k) and thereby feed it into the collecting line 7 . A total amount of water W, which is supplied to the collecting line 7, is the sum of the individual water amounts wi: $$W={\displaystyle \sum _{i=1}^{k}wi}$$

Branch lines 9 go from the collecting line 7 to the application devices 4 . In the branch lines 9 valves 10 are usually arranged. The valves 10 can be switching valves that can only be switched between the “fully open” and “fully closed” states in binary fashion. Alternatively, they may be control valves that can be adjusted between fully open and fully closed states continuously or in multiple stages. The branch lines 9, the valves 10 and also the control of the valves 10 are of secondary importance within the scope of the present invention. It is also of secondary importance within the scope of the present invention whether risers or buffer storage tanks are connected to the collecting line 7 and/or the stub lines 9, the latter being able to temporarily and to a limited extent store water quantities and release them again.

The cooling device 1 is controlled by a control device 11 . The control device 11 is generally in the form of a software-programmable controller and is programmed with a computer program 12 . The computer program 12 includes machine code 13 which can be processed by the control device 11 . The execution of the machine code 13 by the controller 11 causes the controller 11 to operate the cooling device 1 according to an operating method as described below in connection with FIG 2 is explained in more detail.

According to 2 Steps S1 to S5 are cyclically executed by the control device 11. Execution usually takes place within a fixed cycle time, which is typically between 100 ms and 1000 ms, for example between 200 ms and 500 ms, in particular around 300 ms.

In step S1, the control device 11--valid for the respective cycle--knows a target total water quantity W*. The target total amount of water W* is that amount of water that is to be pumped from the pump arrangement 6 into the collecting line 7 in the respective cycle. It is possible for the target total water quantity W* (more precisely: the corresponding numerical value) to be preset for the control device 11 from the outside. It is also possible for the control device 11 to determine the target total water quantity W* itself using other information. It is also possible for the control device 11 not only to know the individual value for the respective cycle, but also a larger time profile. It is crucial that the control device 11 knows the value for the respective cycle after the execution of step S1.

In step S2, the control device 11—again valid for the respective cycle—knows a target pressure p*. The target pressure p* is the pressure on the output side of the pump arrangement 6 (that is towards the collecting line 7) which must be generated by the pump arrangement 6 so that the target total water quantity W* flows in the collecting line 7. The target pressure p* is uniform for all pumps 8 of the pump arrangement 6.

The manner in which the control device 11 becomes aware of the setpoint pressure p* is of secondary importance. As a rule, the setpoint pressure p* is calculated by the control device 11 itself in step S2. Appropriate procedures are known to those skilled in the art. Purely by way of example, reference can be made to the one already mentioned WO 2019/115 145 A1 to get expelled. It is possible that only the individual value for the respective cycle becomes known to the control device 11 in step S2. However, it is also possible for the control device 11 to know a longer course over time. It is crucial that the control device 11 knows the value for the respective cycle after the execution of step S2.

In step S3, the control device 11 determines a respective target individual water quantity wi* for the pumps 8 (with i=1, 2, . . . k). The determination is made in such a way that the sum of the desired individual water quantities wi* is equal to the respective desired total water quantity W*, ie the desired total water quantity W* valid for the respective cycle. The manner in which the control device 11 determines the target individual water quantities wi* can be selected as required. For example, in the simplest case, if there are no special specifications to be taken into account for individual pumps 8 (more on this later), the desired total water quantity W* can be evenly distributed over the pumps 8 .

In step S4, the control device 11 determines the respective speed ni for the pumps 8 (with i=1, 2, . . . k). The determination is made for the respective pump 8 on the basis of the respective desired individual water quantity wi* and the desired pressure p* (uniform for the pumps 8). In particular, the control device 11 determines the difference between the setpoint pressure p* and a suction pressure present on the inlet side of the pumps 8 and then evaluates this pressure difference. The control device 11 evaluates characteristic curves or characteristic curve fields of the pumps 8 for determining the speeds ni. The characteristic curves and the characteristic curve fields are generally known to those skilled in the art. They indicate the functional relationship between the pressure difference, the pumped water volume and the speed. In step S5, the control device 11 controls the pumps 8 according to the speed ni determined in each case.

As far as has been explained so far, the mode of operation of the cooling device 1 (including the control device 11) is the same as in the prior art. What is new, however, are the ways in which a pump 8 is decoupled from the pump arrangement 6 and in which a pump 8 is coupled into the pump arrangement 6 . These procedures are described below in connection with the 3 until 5 explained.

The explanations for 3 until 5 are based on the specific design 1 , that is specifically on the assumption that the pump arrangement 6 has four pumps 8 . Even if the procedures are explained below in connection with a total of four pumps 8, the procedures are independent of the specific number of pumps 8. The pumps 8 are subsequently partly referred to as pumps 8i (with i=1 to 4), i.e. as a result referred to as pumps 81-84. This only serves to be able to reference the pumps 8 individually if required.

In the context of 3 it is explained how an individual pump 8 is decoupled from the pump arrangement 6 . It is assumed here that the pump 81 is specifically to be decoupled.

In order to decouple the pump 81 from the pump arrangement 6, a time course of the target individual water quantity w1* is determined for the pump 81. It is possible for the control device 11 to make this determination. Alternatively, it is possible for the determination to take place elsewhere and for the control device 11 to be specified. What matters is that the target singles amount of water w1* of the pump 81 as shown in 3 falls from an initial value w10* to an end value of 0 during a decoupling time T1. The initial value w10* can, for example, be the value that the target individual water quantity w1* has immediately before the start of the decoupling time T1. The decoupling time T1 is usually in the range of several seconds, but in any case it corresponds to several cycles. The drop to the final value of 0 can be linear, for example.

The specification of the time profile of the desired individual water quantity w1* means that the control device 11 determines the desired individual water quantity w1* for the pump 81 during the decoupling time T1 according to the time profile. The step S3 of 2 is modified in such a way that the target individual water quantity w1* for pump 81 is determined by the specified curve and control device 11 only determines the target individual water quantities w2* to w4* for pumps 82 to 84 in such a way that the sum of Target individual water quantities w1* to w4* is equal to the target total water quantity W*. 3 shows - purely by way of example - a possible time profile of the target total water volume W* and the time profile of a target residual water volume W* for the pumps 82 to 84. The target residual water volume W* results from the difference between the target total water volume W* and the target individual water quantity w1* determined by the specified course and valid for the respective cycle: $$W\text{'}*=W*-\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="DE102021001967A1\_0005.png,DE102021001967A1\_0009.png"\; state="\{\{state\}\}">w</figure-callout>}1*$$

For the pumps 82 to 84, the associated individual water quantities w2* to w4* can be determined in step S3, as has already been explained above for step S3. For example--but now limited to the pumps 82 to 84--an equal distribution can take place.

As soon as the target individual water quantity w1* has reached the final value of 0, check valves 14 upstream and downstream of the pump 81 can be closed, for example. Then the pump 81 can be switched off. Both the closing of the check valves 14 and the switching off of the pump 81 can be carried out manually or by the control device 11 . Both the closing of the check valves 14 and the switching off of the pump 81 have no effect on the operation of the cooling device 1. In particular, no pressure surge is generated. The reason is that the pump 81 is not pumping any water 5 at these times and therefore the closing of the check valve 14 in particular has no influence on the total water quantity W pumped. It is important, however, that during the decoupling time T1 (more precisely: until the check valves 14 are closed), the speed n1 of the pump 81 is always tracked, so that the pump 81 generates both the setpoint pressure p* and the pressure p* specified by the time profile Desired individual water quantity w1* promotes.

After decoupling the pump 81, the procedure of 2 continued to run. The difference to the procedure with pump 81 coupled in is that steps S3 to S5 are now only carried out for pumps 82 to 84 .

Now in the context of 4 explains how a single pump 8 is coupled into the pump assembly 6. It is assumed here that the pump 84 is to be coupled in specifically.

• Zum Einkoppeln der Pumpe 84 in die Pumpenanordnung 6 wird für die Pumpe 84 ein zeitlicher Verlauf von deren Soll-Einzelwassermenge w4* bestimmt. Es ist möglich, dass diese Bestimmung von der Steuereinrichtung 11 vorgenommen wird. Alternativ ist es möglich, dass die Bestimmung anderweitig erfolgt und der Steuereinrichtung 11 vorgegeben wird. Entscheidend ist, dass die Soll-Einzelwassermenge w4* der Pumpe 84 entsprechend der Darstellung in 4 während einer Einkoppelzeit T2 von einem Anfangswert von 0 auf einen Endwert w41* ansteigt. Die Einkoppelzeit T2 liegt meist im Bereich mehrerer Sekunden, in jedem Fall aber beträgt sie mehrere Zyklen. Sie kann - nicht aber muss - gleich der Auskoppelzeit T1 sein. Das Ansteigen auf den Endwert w41* kann beispielsweise linear erfolgen.

At its core is the approach 4 inverse to the procedure of 3 :

• In order to couple the pump 84 into the pump arrangement 6, a time course of the desired individual water quantity w4* is determined for the pump 84. It is possible for the control device 11 to make this determination. Alternatively, it is possible for the determination to take place elsewhere and for the control device 11 to be specified. It is crucial that the target individual water quantity w4* of the pump 84 corresponds to the representation in 4 increases from an initial value of 0 to a final value w41* during a coupling time T2. The coupling time T2 is usually in the range of several seconds, but in any case it is several cycles. It can - but does not have to - be equal to the decoupling time T1. The increase to the final value w41* can be linear, for example.

Initially check valves 15 before and after the pump 84 are closed and the pump 84 is switched off. During the iterative execution of steps S1 to S5, control device 11 only takes pumps 81 to 83 into account.

In order to couple the pump 84, the pump 84 is first operated by the control device 11 at a speed n4 so that although it generates the target pressure p*, the delivered individual water quantity w4 has the value 0. The speed n4 is already tracked accordingly by the control device 11 at this point in time, ie updated in each cycle. Then the check valves 15 are opened. These measures take place before the start of the coupling time T2.

The specification of the time profile of the target individual water quantity w4* means that the control device 11 sets the target individual water quantity w4* for the pump 84 during the coupling time T2 determined according to the course of time. The step S3 of 2 is modified in such a way that the target individual water quantity w4* for pump 84 is determined by the specified curve and control device 11 only determines the target individual water quantities w1* to w3* for pumps 81 to 83 in such a way that the sum of Target individual water quantities w1*to w4* is equal to the target total water quantity W*. 4 shows - purely by way of example - a possible time profile of the desired total water quantity W* and the time profile of a desired residual water quantity W''* for the pumps 81 to 83. The desired residual water quantity W''* results from the difference between the desired Total water quantity W* and the target individual water quantity w4* determined by the specified course and valid for the respective cycle: $$W\text{'}\text{'}*=W*-\mathrm{<figure-callout\; id="4"\; label="w"\; filenames="DE102021001967A1\_0005.png,DE102021001967A1\_0006.png"\; state="\{\{state\}\}">w</figure-callout>}4*$$

For the pumps 81 to 83, the associated setpoint individual water quantities w1* to w3* can be determined in step S3, as has already been explained above for step S3. For example--but limited to the pumps 81 to 83--an equal distribution can take place.

After the end of the coupling time T2, the control device 11 determines the desired individual water quantities wi* for all the pumps 8—ie also for the pump 84—as has already been explained above for step S3.

The procedures of 3 and 4 can also be combined with each other. Execution one after the other is completely problem-free, so that the decoupling of a pump 8 on the one hand and the coupling of a pump 8 on the other hand do not overlap in time. However, it is also possible to decouple one pump 8 and couple another pump 8, with the decoupling of one pump 8 on the one hand and the coupling of another pump 8 on the other hand overlapping in time. This is discussed below in connection with 5 explained. It is assumed here that pump 81 is specifically to be decoupled and pump 84 is specifically to be engaged.

The blocking valves 14, 15 can be opened and closed in the same way as described above in connection with FIG 3 and 4 was explained. The opening and blocking of the shut-off valves 14, 15 is particularly easy because the pumps 81 and 84 are operated at the times at which the shut-off valves 14, 15 are opened or blocked in such a way that the associated target individual water quantities w1 *, w4* each have the value 0. During the respective coupling time T1, T2, the respective target individual water quantity w1*, w4* is determined according to the respective time profile. If at a certain point in time only the pump 81 is decoupled, i.e. the pump 84 is either not yet coupled or is already fully coupled, the target residual water quantity W'* for the pumps 82 to 84 is determined according to Equation 2. If for a At a specific point in time only pump 84 is coupled, i.e. pump 81 is either not yet decoupled or is already completely decoupled, the target residual water quantity W''* for pumps 81 to 83 is determined according to Equation 3. If at a specific point in time If both pump 81 is decoupled and pump 84 is coupled in, the target residual water quantity w2*+w3* for pumps 82 and 83 is determined according to Equation 4: $$\mathrm{<figure-callout\; id="2"\; label="w"\; filenames="DE102021001967A1\_0005.png,DE102021001967A1\_0006.png"\; state="\{\{state\}\}">w</figure-callout>}2*+w3*=W*-\mathrm{<figure-callout\; id="1"\; label="w"\; filenames="DE102021001967A1\_0005.png,DE102021001967A1\_0009.png"\; state="\{\{state\}\}">w</figure-callout>}1*-\mathrm{<figure-callout\; id="4"\; label="w"\; filenames="DE102021001967A1\_0005.png,DE102021001967A1\_0006.png"\; state="\{\{state\}\}">w</figure-callout>}4*$$

The target residual water quantity W* or W″* or w2*+w3* is distributed to the “free” pumps 8, whose respective target individual water quantity wi* can therefore be freely determined by the control device 11, as described above explained in connection with step S3.

The other pumps 82, 83 can also be decoupled from the pump arrangement 6 and coupled into the pump arrangement 6 as required in a completely analogous manner. In this case, check valves 16, 17, which are arranged upstream and downstream of these pumps 82, 83, are also actuated as required.

The present invention has many advantages. In particular, a completely reaction-free coupling of pumps 8 into the pump arrangement 6 and an equally completely reaction-free decoupling of pumps 8 from the pump arrangement 6 is possible in a simple and reliable manner. The procedures are readily applicable to multiple pumps 8. It is therefore possible for several pumps 8 to be coupled and/or decoupled at the same time, completely independently of one another. It only has to be ensured that at least one “free” pump 8 remains, which can pump the resulting target residual water quantity W* or W″* or—for example w2*+w3*. Check valves are not required. Only at least on the output side of the pumps 8 check valves 14 to 17 are required. Due to the reaction-free mode of operation, pumps 8 can also be coupled in and/or decoupled much more frequently than in the prior art. As a result, the energy efficiency in particular can be increased.

Finally, it should be noted that the operation of a pump 8 with a target individual water quantity wi* of 0 usually results in an impermissible gen operating state. Long-term operation of the corresponding pump 8 in this operating state would therefore lead to damage. However, short-term operation (a few seconds) is possible without any problems and does not cause any additional wear.

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived therefrom by a person skilled in the art without departing from the protective scope of the invention.

Reference List

1

cooling device

2

rolling stock

3

last rolling stand

4

application devices

5

water

6

pump arrangement

7

manifold

8, 8i

pump

9

stubs

10

valves

11

control device

12

computer program

13

machine code

14 to 17

check valves

k

number of pumps

no

speeds

p*

target pressure

S1 to S5

steps

T1

decoupling time

T2

coupling time

W

total amount of water

W*

Target total water volume

W'*, W''*

Target residual water quantities

wi

single water amounts

w*

Target individual water quantities

w10*

initial value

w41*

final value

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2013/143925 A1 [0014]
• EP20169308 [0014]
• WO 2019/115145 A1 [0015, 0032]

Claims (7)

Operating method for a cooling device (1) for cooling a hot rolling stock (2) made of metal, - the cooling device (1) having a number of application devices (4) by means of which water (5) is applied to the rolling stock (2), - A pump arrangement (6) is arranged upstream of the application devices (4), by means of which the water (5) is pumped via a collecting line (7) to the application devices (4), - the pump arrangement (6) having a plurality of pumps (8) connected in parallel has, so that a total amount of water (W) fed into the collecting line (7) by the pumps (8) is equal to the sum of individual amounts of water (wi) pumped by a respective individual pump (8), with the following cyclically executed steps : - a target total water quantity (W*) and a target pressure (p*) on the outlet side of the pump arrangement (6) are known to a control device (11) of the cooling device (1), - the control device (11) determines for the pumps (8 ) a respective target - Individual water quantity (wi*), so that the sum of the target individual water quantities (wi*) is equal to the respective target total water quantity (W*), - the control device (11) determines for the pumps (8) using the respective target individual water quantity (wi*) and the target pressure (p*) the respective speed (ni), - the control device (11) controls the pumps (8) according to the respectively determined speed (ni), characterized in that for decoupling a pump (81) from the pump arrangement (6) for the pump (81) to be decoupled, a time profile of its target individual water quantity (w1*) is determined in such a way that the target individual water quantity (w1*) of the pump (81) to be decoupled during a decoupling time (T1) from an initial value (w10*) above 0 to a final value of 0 and that the control device (11) sets the target individual water quantity (w1*) for the pump (81) to be decoupled during the decoupling time (T1) according to the time course determined. Operating method for a cooling device (1) for cooling a hot rolling stock (2) made of metal, - the cooling device (1) having a number of application devices (4) by means of which water (5) is applied to the rolling stock (2), - A pump arrangement (6) is arranged upstream of the application devices (4), by means of which the water (5) is pumped via a collecting line (7) to the application devices (4), - the pump arrangement (6) having a plurality of pumps (8) connected in parallel has, so that a total amount of water (W) fed into the collecting line (7) by the pumps (8) is equal to the sum of individual amounts of water (wi) pumped by a respective individual pump (8), with the following cyclically executed steps : - a target total water quantity (W*) and a target pressure (p*) on the outlet side of the pump arrangement (6) are known to a control device (11) of the cooling device (1), - the control device (11) determines for the pumps (8 ) a respective target - Individual water quantity (wi*), so that the sum of the target individual water quantities (wi*) is equal to the respective target total water quantity (W*), - the control device (11) determines for the pumps (8) using the respective target individual water quantity (wi*) and the target pressure (p*) the respective speed (ni), - the control device (11) controls the pumps (8) according to the respectively determined speed (ni), characterized in that for coupling a pump (84) in the pump arrangement (6) for the pump (84) to be coupled in, a time profile of its target individual water quantity (w4*) is determined in such a way that the target individual water quantity (w4*) of the pump (84) to be coupled in during a coupling time (T2) from an initial value of 0 to a final value (w41*) above 0, and that the control device (11) adjusts the target individual water quantity (w4*) for the pump (84) to be coupled in during the coupling time (T2) according to determined over time. operating procedures claim 2 , characterized in that for decoupling a pump (81) different from the pump (84) to be coupled into the pump arrangement (6) from the pump arrangement (6) for the pump (81) to be decoupled, a time profile of its target individual water quantity (w1* ) is determined in such a way that the target individual water quantity (w1*) of the pump (81) to be decoupled falls from an initial value (w10*) above 0 to a final value of 0 during a decoupling time (T1), and that the control device (11) the target individual water quantity (w1*) for the pump (81) to be decoupled is determined during the decoupling time (T1) according to the course over time. operating procedures claim 3 , characterized in that the coupling time (T2) and the decoupling time (T1) overlap. Computer program comprising machine code (13) which can be processed by a control device (11) for a cooling device (1) for cooling a hot rolling stock (2) made of metal, the processing of the machine code (13) being effected by the control device (11). , that - the control device (11) knows a target total water quantity (W*) and a target pressure (p*) on the outlet side of the pump arrangement (6), - the control device (11) for the pumps (8) a respective target individual water quantity ( wi*) determined so that the sum of the target individual water quantities (wi*) is equal to the target total water quantity (W*), - the control device (11) for the pumps (8) based on the respective target individual water quantity (wi*) and the setpoint pressure (p*) determines the respective speed (ni), - the control device (11) controls the pumps (8) according to the speed (ni) determined in each case and - the control device (11) determines the desired individual water quantity (w1 *) determined for a pump (81) to be decoupled from the pump arrangement (6) during a decoupling time (d1) according to a time profile of its target individual water quantity (w1*), the time profile during the decoupling time (T1) starting from an initial value ( w10*) falls above 0 to a final value of 0, and/or the S oll individual water quantity (w4*) for a pump (84) to be coupled into the pump arrangement (6) during a coupling time (T2) according to a time profile of its target individual water quantity (w4*), the time profile during the coupling time (T2 ) increases from an initial value of 0 to a final value (w41*) above 0. Control device for a cooling device (1) for cooling a hot rolling stock (2) made of metal, the control device having a computer program (12). claim 5 is programmed so that the control device operates the cooling device (1) according to an operating method according to one of the above claims. Cooling device for cooling a hot rolling stock (2) made of metal, - the cooling device having a number of application devices (4) by means of which water (5) is applied to the rolling stock (2), - the application devices (4) having a pump arrangement ( 6) is arranged upstream, by means of which the water (5) is pumped via a collecting line (7) to the application devices (4), - the pump arrangement (6) having a plurality of pumps (8) connected in parallel, so that one of the pumps ( 8) the total amount of water (W) fed into the collecting line (7) is equal to the sum of individual amounts of water (wi) pumped by a respective individual pump (8), - the cooling device having a control device (11). claim 6 having, which operates the cooling device according to an operating method according to any one of the above claims.

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