Run the cooling unit at minimum operating pressure

Abstract

The cooling device is operated at a minimum operating pressure. A fluid coolant (6) is fed into the manifold (4) via a pump device (5). Branches (9a to 9d) provided with regulating valves (11a to 11d) leave the manifold (4) and lead to application devices (10a to 10d). The coolant (6) is applied to the hot rolled metal piece (2) by means of the application devices (10a to 10d), thereby cooling the rolled metal piece (2). The control device (12) of the cooling device (3) determines a separate operating pressure, which must be present in the manifold (4), for the set flow (Ka* to Kd*) of the application device (10a to 10d) to the limiting modulation value of the regulating valves (11a to 11d), so that the set flow (Ka* to Kd*) flows in the branches (9a to 9d). The control device then determines a temporary control state of the pump device (5) such that the sum of the setpoint flows (Ka* to Kd*) is supplied to the manifold (4) and a temporary working pressure exists in the manifold (4) at the same time, which corresponds to at least the maximum individual working pressure. The control device determines a final control state (Z') of the pump device (5) using the temporary control state such that the total flow (K) is supplied to the manifold (4) and a final working pressure (pAe) exists in the manifold (4). The control device then determines the control values (Aa to Ad) of the control valves (11a to 11d) using the final working pressure (pAe) such that the setpoint flows (Ka* to Kd*) flow in the branches (9a to 9d). The control device controls the pump device (5) and the control valves (11a to 11d) accordingly.

Description

Technical Field

[0001] The invention is based on a method for operating a cooling device for cooling hot-rolled metal products.

[0002] wherein the cooling device comprises a header into which the fluid coolant is fed by means of a pump device and from which a plurality of branches lead to the application device,

[0003] wherein the pump device comprises a plurality of pumps, the regulating valves are each arranged in a branch, and the coolant is applied to the rolled stock by means of at least one part of the application device,

[0004] wherein a setpoint flow is known to the control device of the cooling device, which setpoint flow is to be supplied to the application device,

[0005] The control device actuates the pump device as a function of the final actuation state and actuates the regulating valve as a function of the actuation value.

[0006] The present invention is further based on a computer program comprising a machine code that can be executed by a control device of a cooling device for cooling hot-rolled metal products, wherein the execution of the machine code by the control device causes the control device to operate the cooling device according to the operating method.

[0007] The present invention is further based on a control device for a cooling device for cooling hot-rolled metal stock, wherein the control device is programmed with such a computer program in such a way that it operates the cooling device according to such an operating method.

[0008] The invention is further based on a cooling device for cooling hot-rolled metal products.

[0009] wherein the cooling device comprises a manifold, a pump device and a plurality of application devices,

[0010] - wherein the fluid coolant is applied to the rolled stock by means of at least a part of the application device,

[0011] - wherein the application devices are connected to the collecting pipe via respective branches,

[0012] wherein the pump device comprises a plurality of pumps, by means of which the fluid coolant is fed into the collecting pipe,

[0013] - wherein a regulating valve is respectively arranged in each branch,

[0014] The cooling device comprises a control device which operates the cooling device according to the operating method. Background Art

[0015] The above-mentioned subject matter is well known.

[0016] For example, WO 2013 / 143 925 A1 discloses a cooling device for cooling hot-rolled metal workpieces, wherein a fluid coolant is fed into a manifold by a pump device, from which branches branch off to an application device, by means of which the coolant is applied to the workpiece. A regulating valve is arranged in the branch. A control device determines the control state for the pump device and the control value for the regulating valve based on its known nominal flow rate to be supplied to the application device, and controls the pump device and the regulating valve accordingly. In WO 2013 / 143 925 A1, the manifold is either under high pressure or under low pressure. A higher coolant pressure is only generated when it is actually required. A demand for a higher pressure is considered to be given if, under low pressure, the opening position of at least one valve would exceed a specific opening position predetermined as a limit value.

[0017] WO 2014 / 124 867 A1 also discloses a cooling device for cooling hot-rolled metal products, in which a fluid coolant is fed into a manifold by a pump device. Branches from the manifold lead to an application device, which applies the coolant to the rolled product. A regulating valve is arranged in the branch. The setpoint flow rate to be supplied to the application device is known to the control device of the cooling device. The control device determines the corresponding control value of the regulating valve and controls it accordingly. WO 2014 / 124 867 A1 does not contain any information regarding the (optionally variable) control of the pump.

[0018] WO 2014 / 124 868 A1 also discloses a cooling device for cooling hot-rolled metal workpieces, in which a fluid coolant is fed into a manifold by a pump device, from which branches branch off to an application device, by means of which the coolant is applied to the workpiece. A regulating valve is arranged in the branch. A control device of the cooling device determines the total flow rate based on the rated flow rate to be supplied to the application device and, based on the total flow rate, determines the control state of the pump device. The operating pressure in the manifold can be adjusted between a minimum and a maximum value. The regulating valve can be adjusted between a fully closed and a fully open position. To adjust the respective rated flow rates, the control device changes not only the opening position of the valve but also the line pressure generated by the pump in the manifold.

[0019] WO 2019 / 115 145A1 also discloses a cooling device for cooling hot-rolled metal products, in which a fluid coolant is fed into a manifold by means of a pump device, from which branches lead to an application device, by means of which the coolant is applied to the rolled product. A regulating valve is arranged in the branch. The control device determines the control state for the pump device based on the rated flow to be supplied to the application device. In addition to the total amount of water to be conducted, the control device also takes into account changes in the water volume and the line resistance. If the opening position of the regulating valve does not exceed the minimum distance from the minimum possible opening position and the maximum possible opening position, the control state of the pump is adapted and thus the working pressure is also adapted.

[0020] WO 2020 / 020 868 A1 discloses a cooling device for cooling hot-rolled metal workpieces, in which a fluid coolant is applied to the workpiece by means of multiple application devices. Each application device is fed by its own pump. The valve between each pump and the application device is continuously kept fully open. The amount of coolant delivered is adjusted solely by corresponding time-varying control of the pumps. Summary of the Invention

[0021] In particular, with forced cooling, but sometimes even with laminar cooling, the control valves are fed via a pump. A typical arrangement in this case is to supply several control valves via a manifold, with the manifold being supplied with coolant by a pump arrangement. The pump arrangement can have one pump or also several pumps.

[0022] The coolant is applied to the rolled stock by means of an application device, which is often designed as a spray beam. In some cases, there may be additional application devices which do not apply the coolant to the rolled stock but discharge it in another way. This is for example for homogenization. The total amount of coolant delivered may be of interest.

[0023] The object of the present invention is to provide a possibility by means of which conventional cooling devices, ie cooling devices in which the coolant applied to the rolled product is metered by actuating a control valve, can be operated in an improved manner.

[0024] This object is achieved by a method for operating a cooling device for cooling hot-rolled metal stock. Advantageous embodiments are the subject of further exemplary embodiments.

[0025] According to the invention, an operating method of the type mentioned at the outset is designed in such a way that, in order to determine the final actuation state of the pump device and the actuation value of the regulating valve, the control device

[0026] determining a respective individual operating pressure for the regulating valve for the respective limiting modulation value of the respective regulating valve, which must prevail in the manifold in order for the respective setpoint flow to flow in the respective branch,

[0027] - determining a temporary control state of the pump device such that a total flow of coolant is delivered to the manifold by means of the pump device, the total flow corresponding to the sum of the setpoint flows, and at the same time a temporary operating pressure prevails in the manifold, the temporary operating pressure being at least as great as the maximum of the individual operating pressures,

[0028] - using the temporary control state of the pump device, determining a final control state of the pump device, so that the total flow of coolant is delivered to the manifold by means of the pump device and at the same time a final operating pressure prevails in the manifold, and

[0029] Using the final operating pressure, the control values of the control valves are determined so that the respective setpoint flow flows in the respective branch.

[0030] This ensures that the pump device of the cooling device is operated at the lowest possible final operating pressure and thus at the lowest possible energy consumption, while the rolled stock is nevertheless cooled at any time according to the required nominal flow rate.

[0031] It is possible that the limiting modulation factor of a control valve is the maximum modulation factor of the control valve. However, in order to achieve a certain regulation reserve, it may be advantageous if the limiting modulation factor of the control valve is slightly lower than this, that is, only close to the maximum modulation factor of the control valve. In the last-mentioned case, the limiting modulation factor of the control valve thus corresponds to a high percentage of the maximum modulation factor of the control valve, for example 80%, 90% or 95%. Of course, the limiting modulation factor can also have other values. However, in particular, it should not exceed a value of 80%. These numerical specifications also relate to the coolant flow rate, that is, the effect obtained by controlling the respective control valve. However, the numerical specifications do not relate to the control variables used to control the control valves. The limiting modulation factor can be predefined individually for each control valve as required, or uniformly for all control valves. Grouped presetting is also possible.

[0032] When determining the temporary operating state, the control device preferably takes into account auxiliary conditions associated with the pump device. This ensures that the pump device is always operated within the permissible operating range. The control device can, for example, check whether it can determine a permissible operating state for the pump device, in which the pump device delivers the required total flow and, on the one hand, generates the maximum operating pressure of the determined individual operating pressures in the manifold. If this is the case, this operating pressure, or a value derived directly from it, can be used as the final operating pressure. If this is not the case, the control device can gradually increase the operating pressure, starting from the temporary operating pressure, until a permissible operating state for the pump device is found.

[0033] When determining the temporary operating state, the control device preferably takes into account auxiliary conditions associated with the control valve. For example, the control device can determine the associated control value of the control valve for a permissible operating state of a pump device that, on the one hand, delivers the required total flow and, on the other hand, generates an operating pressure in the manifold that is at least as high as the maximum operating pressure of the individual operating pressures. The control device then checks whether, and if necessary, to what extent, an undesirable state has occurred. If this is the case, the undesirable state can be either tolerated or the operating state of the pump device can be adapted. The decision on which measures to take can be made based on the individual situation.

[0034] When determining the final operating state of the pump device, the control device preferably also takes into account at least one previous final operating state of the pump device and / or at least one future expected temporary operating state of the pump device. For example, the control device can perform a model-predictive determination of the temporary operating state. The control device can also, for example, formulate an optimization problem, which includes, on the one hand, the minimization of the temporary operating pressure according to the present invention and, on the other hand, other facts. Examples of such facts are changes in the temporary or final operating pressure and changes in the operating state of the pump device.

[0035] This object is further achieved by a computer program product. According to the invention, the execution of the computer program causes the control device to operate the cooling device according to the operating method according to the invention.

[0036] This object is also achieved by a control device for a cooling device for cooling hot-rolled metal stock. According to the invention, the control device is programmed with the computer program according to the invention so that the control device operates the cooling device according to the operating method according to the invention.

[0037] This object is achieved by a cooling device for cooling hot-rolled metal products. According to the invention, a cooling device of the type mentioned at the outset has a control device according to the invention, which operates the cooling device according to the operating method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The above-described characteristics, features and advantages of the present invention and the manner in which they are achieved will become clearer and more clearly understood in conjunction with the following description of an embodiment, which is explained in more detail in conjunction with the accompanying drawings. In this case, a schematic diagram:

[0039] Figure 1 Showing a rolling line with cooling device,

[0040] Figure 2 The characteristic curve of the regulating valve is shown.

[0041] Figure 3 Showing a flow chart,

[0042] Figure 4 The characteristic curve of the pump is shown.

[0043] Figure 5 Showing a flow chart,

[0044] Figure 6 The pump device is shown,

[0045] Figure 7 shows a flow chart, and

[0046] Figure 8 A flow chart is shown. DETAILED DESCRIPTION

[0047] according to Figure 1 , a rolling line (Walzlinie) has at least one rolling mill stand 1. Figure 1 Only a single rolling mill stand 1 is shown. However, in many cases, there are multiple rolling mill stands 1 arranged one after the other, so that the rolling line is configured as a rolling mill train. A hot-rolled stock 2 is rolled in the rolling line, i.e., its cross-section is reduced. The stock 2 can consist of, for example, steel or aluminum. However, it can also consist of other metals, such as brass or copper. The stock 2 can be a flat stock, such as a strip or plate. However, it can also have other shapes, such as a rod, a profile, or a tube.

[0048] The rolling line also has a cooling device 3. Figure 1In the illustration, the cooling device 3 is arranged downstream of the rolling stand 1. However, this is not absolutely necessary. The cooling device 3 can also be arranged upstream of the rolling stand 1, for example, in the form of a so-called inter-stand cooling device between the finishing stands of a multi-stand finishing train or in the form of a pre-strip cooling device between the first finishing stand and the roughing stand of a multi-stand finishing train. Other arrangements are also possible.

[0049] The cooling device 3 has a header 4. A fluid coolant 6 is fed into the header 4 via a pump device 5. For example, the pump device 5 can be connected to a container 7 on the input side for this purpose. However, other designs are also possible, such as supplying the pump device 5 directly via a water distribution network. Figure 1 The pump device 5 can have a plurality of pumps 8. Figure 1 In the embodiment of the invention, the pumps 8 are connected in parallel with one another. However, the pumps 8 can also be arranged one after another in series. Combinations of the described operating modes are also possible, for example three branches in which two pumps 8 are each arranged one after another in series. It is also possible to have only a single pump 8. The coolant 6 is mostly water or at least consists essentially (98% or more) of water.

[0050] Branches 9a to 9d lead from the header 4 to application devices 10a to 10d. Application devices 10a to 10d are therefore connected to the header 4 via branches 9a to 9d. Coolant 6 is applied to the rolled stock 2 by means of the application devices 10a to 10d. Application devices 10a to 10d can be designed, for example, as so-called cooling beams or spray beams.

[0051] according to Figure 1 , the application devices 10a to 10d are arranged above the rolled stock 2 and thus apply the coolant 6 to the rolled stock 2 from above. However, this is not absolutely necessary. The application devices 10a to 10d can also be arranged below the rolled stock 2 or at other locations. It is also possible that the application devices 10a to 10d apply the coolant 6 to the rolled stock 2 from different sides. It is also possible that not all application devices 10a to 10d apply the coolant 6 to the rolled stock 2, but that at least one of the application devices 10a to 10d (if so, usually one or two) does not apply the coolant 6 to the rolled stock 2. For example, the corresponding design and the reasons for this are explained in the aforementioned WO 2019 / 115 145 A1.

[0052] In addition, Figure 1, a total of four application devices 10a to 10d are shown. The present invention is explained with reference to this number of application devices 10a to 10d. However, the number of application devices 10a to 10d can also be greater or lesser. The number simply needs to be greater than one. Therefore, there are at least two application devices 10a to 10d, which are connected to the manifold 4 via two branches 9a to 9d, with a respective regulating valve 11a to 11d being arranged in each of the branches 9a to 9d.

[0053] The regulating valves 11a to 11d are arranged in the branches 9a to 9d. The regulating valves 11a to 11d can be constructed as ball valves, for example. However, regardless of their specific design, the regulating valves 11a to 11d can be continuously adjusted. Figure 2 The illustration in FIG illustrates the term “continuous regulation” for the regulating valve 11 a . Similar statements apply to the other regulating valves 11 b to 11 d .

[0054] according to Figure 2 The regulating valve 11a is controlled using the manipulated value Aa. The manipulated value Aa lies between a minimum manipulated value Amin and a maximum manipulated value Amax. The manipulated value Aa can be varied continuously or at least in multiple steps. The manipulated value Aa can therefore assume multiple possible values between the minimum manipulated value Amin and the maximum manipulated value Amax (if necessary within the limits of control accuracy). For example, in the case of a ball valve, the minimum manipulated value Amin and the maximum manipulated value Amax can lie at 0° and 90°, and the manipulated value Aa can be adjusted between these two extreme values Amin, Amax in steps of, for example, 0.1° or 0.2°.

[0055] Given a reference pressure pR at the inlet of the control valve 11a, a corresponding reference coolant flow KR flows through the control valve 11a and, therefore, through the corresponding branch 9a, depending on the control value Aa. Due to the possibility of continuously adjusting the control valve 11a, the reference coolant flow KR also experiences a corresponding range of values between a minimum value KRmin (mostly 0) and a maximum value KRmax (which is, of course, greater than the minimum value KRmin). The reference coolant flow KR divided by the maximum value KRmax corresponds to the modulation factor ka of the control valve 11a. The modulation factor ka has a maximum value of 1 and typically a minimum value of 0.

[0056] The functional relationship of the reference coolant flow KR (or equivalently the modulation factor ka) as a function of the manipulated value Aa corresponds to the characteristic curve for the regulating valve 11a. Figure 2As shown in the diagram, the characteristic curve is often nonlinear. However, there is usually a strictly monotonic relationship between the control value Aa and the reference coolant flow KR or the modulation factor ka on the one hand. As the person skilled in the art also knows, as long as the working pressure pA present on the input side of the control valve 11a is known, the actual coolant flow Ka - that is, the amount of coolant 6 actually flowing through the control valve 11a - can be easily determined at a given control value Aa. In particular, the value obtained from the characteristic curve itself only needs to be scaled using the square root (Wurzel) of the quotient of the working pressure pA and the reference pressure pR. The working pressure pA and the reference pressure pR must also be corrected for an offset if necessary. With a given modulation factor ka and a known maximum reference coolant flow KRmax and a known working pressure pA, the coolant flow Ka is obtained as follows:

[0057]

[0058] ρ is the density of the coolant 6, g is the acceleration due to gravity, and ha is the height of the valve outlet (or application device 10a) relative to a reference level that is uniform for all application devices 10a to 10d. Depending on the arrangement of the valve outlet relative to the reference level, hA can be greater than or less than 0. The reference level can be selected as required. For example, the reference level can correspond to the level of the roller conveyor by which the rolled product 2 is transported through the cooling device 3. The associated control value Aa is derived directly from the characteristic curve after determining the modulation factor ka.

[0059] The cooling device 3 further comprises a control device 12 which controls and operates the cooling device 3. The control device 12 is usually designed as a software programmable device. Figure 1 This is indicated by the fact that the symbol "μP" for the microprocessor is drawn within the control unit 12. The control unit 12 is programmed with a computer program 13. The computer program 13 comprises a machine code that can be executed by the control unit 12. As a result of programming or executing the machine code 14 with the computer program 13, the control unit 12 is operated according to the following combination: Figure 3 The operating method explained in more detail is used to operate the cooling device 3 .

[0060] In step S1, the control device 12 receives the setpoint flow rates Ka* to Kd*. The setpoint flow rates Ka* to Kd* (e.g., in liters / second) indicate the amount of coolant 6 that is to be supplied to the respective application device 10a to 10d and discharged by the respective application device 10a to 10d, in particular, to be applied to the rolled product 2. For example, the setpoint flow rates Ka* to Kd* can be externally predetermined for the control device 12 or can be independently determined by the control device 12 based on other circumstances. The corresponding operation is well known to those skilled in the art.

[0061] In step S2, the control device 12 determines the individual operating pressure pAa for the limiting modulation value kLim of the regulating valve 11a. The limiting modulation value kLim is predefined for the control device 12. The limiting modulation value kLim can be the maximum modulation factor of the regulating valve 11a. However, in many cases, if the limiting modulation value is based on Figure 2 The illustration in FIG shows a value that is close to, but below, the maximum modulation factor of the control valve 11a. In this case, the limit modulation value kLim should be at least 80%, preferably at least 90%, and particularly preferably at least 95%. However, a value of 98% should generally not be exceeded. Therefore, the limit modulation factor kLim corresponds to a high percentage of the maximum modulation factor of the control valve 11a. For the sake of clarity, it should be clarified that the limit modulation value kLim relates to the modulation factor ka of the control valve 11a, not to the actuation Aa of the control valve 11a.

[0062] The control device 12 determines the individual working pressure pAa so that, given the working pressure pAa and the limiting modulation factor kLim of the regulating valve 11a, the desired setpoint flow Ka* flows in the branch 9a. The control device 12 determines the working pressure pAa, for example, according to the following equation:

[0063]

[0064] In step S3, the control device 12 determines the individual operating pressures pAb to pAd for the other control valves 11b to 11d in a completely similar manner. The limiting modulation factor kLim, maximum reference coolant flow rate KRmax, and reference pressure pR of the other control valves 11b to 11d can have the same values as the limiting modulation factor kLim, maximum reference coolant flow rate KRmax, and reference pressure pR of the control valve 11a. Alternatively, other values can be used, which can also vary from control valve 11b to 11d to control valve 11b to 11d within the other control valves 11b to 11d, if necessary. However, in each case, the control device 12 determines the individual operating pressures pAb to pAd of the other control valves 11b to 11d independently of each other and also independently of the individual operating pressure pAa of the control valve 11a.

[0065] In step S4, the control device 12 then determines the operating state Z of the pump device 5. The operating state Z is determined so that the pump device 5 (as long as it is operated according to the operating state Z) delivers a total flow K that corresponds to the sum of the rated flows Ka* to Kd*. Due to the delivery of the total flow K, the total flow K of the coolant 6 is also delivered to the manifold 4 by means of the pump device 5. At the same time, the operating state Z is determined so that an operating pressure pAv exists in the manifold 4 that is at least as great as the maximum of the individual operating pressures pAa to pAd. However, both the operating state Z and the operating pressure pAv are only temporary. The operating state Z includes at least the required speed n for each pump 8 of the pump device 5.

[0066] What is important in this context is that the control of the pump device 5 can be varied continuously or at least in multiple steps. Thus, not only is it possible to switch between two or three fixed, discrete control states Z, but the possible control states Z also constitute a continuous or quasi-continuous state. If (purely by way of example) one of the pumps 8 can be operated between a minimum speed nmin of 100 rpm and a maximum speed nmax of 800 rpm, the speed n can also be adjusted to intermediate values between 100 rpm and 800 rpm, such as 150 rpm, 227 rpm, or 593 rpm in the case of stepless adjustability, and to at least ten different steps, such as 100, 150, 200, 250, and so on, up to 800 rpm in the case of stepped adjustability. The numerical values mentioned are, of course, to be understood only as examples.

[0067] It is possible that the control device 12, within the scope of step S4, only considers the static pressure to be generated by the pump device 5. Therefore, it is possible that the control device 12, within the scope of step S4, assumes that the pressure generated on the output side of the pump device 8 is consistent with the pressure on the input side of the control valves 11a to 11d. However, it is also possible that the control device 12 considers additional circumstances. An example of such a circumstance is the time variation of the nominal flow rate Ka* to Kd* and the associated time variation of the total flow rate K and the associated acceleration of the water volume. Another example of such a circumstance is the flow resistance between the pump device 5 and the manifold 4 or within the manifold 4, due to which the pressure generated on the input side of the control valves 11a to 11d is always lower than the pressure generated by the pump device 8. For both of these circumstances, corresponding options for taking them into account can be found in the aforementioned WO 2019 / 115 145 A1. Possible height differences between the pump device 8, on the one hand, and the manifold 4, or a reference level of the manifold 4, on the other hand, can also be taken into account by means of a constant offset.

[0068] In the simplest case, when only a single pump 8 is present, the control device 12 can determine the rotational speed n of the pump, for example, by accessing a characteristic map in which the rotational speed n of the pump is determined according to the characteristic map. Figure 4 The diagram in shows for the pump 8 which rotational speed n of the pump 8 is required to produce a specific pressure increase δp at a specific total flow rate K. In conjunction with the suction pressure pS present on the inlet side of the pump device 5 , the required pressure increase δp=ps−pAv can thus be easily determined. The suction pressure pS can be known to the control device 12 based on measurements or in some other way.

[0069] In many cases, the control state determined for the maximum of the individual working pressures pAa to pAd will already be a permissible control state for the pump device 5. In this case, this control state can be adopted directly as the temporary control state Z. Further possibilities and configurations will be discussed later.

[0070] Then, in step S5, the control device 12 determines the control state Z' of the pump device 5. Unlike the control state Z, the control state Z' is final. The control device 12 determines the final control state Z' of the pump device 5 using the temporary control state Z of the pump device 5. The determination in step S5 is such that the total flow rate K of the coolant 6 is delivered to the manifold 4 by means of the pump device 5. At the same time (assuming that the pump device 5 is controlled according to the final control state Z'), the final operating pressure pAe is present in the manifold 4. In the simplest case, the control device 12 directly and immediately adopts the temporary control state Z as the final control state Z'. It is also possible to increase the temporary operating pressure pAv by a small additive offset or multiply the temporary operating pressure pAv by a factor slightly greater than 1 and thereby determine the final operating pressure pAe. These operating methods are similar in their effect to using a limiting modulation value kLim slightly less than 1. Other possibilities and design solutions for determining the final operating pressure pAe will be discussed later.

[0071] Once the desired total flow K is delivered to the manifold 4 by means of the pump device 8, the final actuation state Z' results in a final operating pressure pAe in the manifold 4. Therefore, in step S6, the control device 12 determines the actuation values Aa to Ad for the regulating valves 11a to 11d using the final operating pressure pAe. This is done so that the respective setpoint flow Ka* to Kd* flows in the respective branch 9a to 9d.

[0072] In the context of the determination in step S6, the control device 12 assumes that the final operating pressure pAe is present in the manifold 4. For example, for the regulating valve 11a, the modulation factor ka is thus

[0073]

[0074] Similar circumstances apply to the other regulating valves 11b to 11d. Based on the now known modulation factors ka to kd of the regulating valves 11a to 11d, the required control values Aa to Ad of the regulating valves 11a to 11d can be determined using the associated characteristic curves.

[0075] In step S7 , the control device 12 actuates the pump device 5 and the regulating valves 11 a to 11 d . The pump device 5 is actuated according to the final actuation state Z′. The regulating valves 11 a to 11 d are actuated according to the actuation values Aa to Ad.

[0076] The operating method according to the present invention is executed by executing step S7. However, generally speaking, after executing step S7, the control device 12 returns to step S1. The control device 12 thus repeatedly executes the sequence of steps S1 to S7. Typically, this is executed with a fixed cycle time. The fixed cycle time is usually between 0.1 s and 1.0 s, and is usually between 0.2 s and 0.5 s, for example, approximately 0.3 s.

[0077] The following combination Figure 5 Explanation Figure 3 A possible design of step S4 is a possible way of determining the temporary operating state Z. Figure 3 Step S4 is based on Figure 5 The process is divided into steps S11 to S14 within the scope of the design of FIG.

[0078] In step S11, the control device 12 determines the operating state of the pump device 5 required to deliver the total flow K and simultaneously to cause the required pressure increase δp from the suction pressure pS to the maximum operating pressure of the determined individual working pressures pAa to pAd. For example, in the case of only one pump 8, the control device 12 can determine the corresponding speed n of the pump 8.

[0079] In step S12, the control device 12 checks whether the determined temporary state Z is permissible, for example whether the determined rotational speed n is within the permissible rotational speed range of the pump 8, that is, whether the operating point of the pump 8 is within the permissible rotational speed range. Figure 4 Therefore, this test includes a test for compliance with the auxiliary conditions associated with the pump device 5.

[0080] It is possible (and even customary) for the speed n to be within the permissible speed range of the pump 8. For example, the operating point AP1 of the pump 8 can be determined from the total flow rate K and the maximum operating pressure of the individual operating pressures pAa to pAd, which is within the permissible speed range of the pump 8. As long as the speed n is within the permissible speed range of the pump 8, the control device 12 proceeds to step S13. In step S13, the control device 12 does not take any further measures. The determined speed n can be used directly.

[0081] However, it is also possible (even if only rarely) that the speed n does not lie within the permissible speed range of the pump 8. For example, the operating point AP2 or the operating point AP3 of the pump 8 can be determined by the total flow rate K and the maximum working pressure of the determined individual working pressures pAa to pAd. At the operating point AP2, the pump 8 can easily generate the maximum working pressure of the determined individual working pressures pAa to pAd. However, due to the permissible speed range of the pump 8, the volume flow delivered by the pump 8 is necessarily greater than the required total flow rate K. The opposite is true at the operating point AP3. The pump 8 can easily generate the required total flow rate K. However, due to the permissible speed range of the pump 8, the pressure increase δp caused by the pump 8 is necessarily greater than the minimum required pressure.

[0082] As long as the speed n is not within the permissible speed range of the pump 8 , the control device 12 proceeds to step S 14 . In step S 14 , the control device 12 modifies the temporary actuation state Z.

[0083] At the operating point AP2, the control device 12 can, for example, control the bypass valve 15 (see Figure 6 ) to determine the open state. Figure 6 , a bypass valve 15 is connected in parallel with the pump 8. The bypass valve can be considered as a component of the pump device 5 or as a regulating valve for another application device. The control device 12 determines the opening state as needed so that enough coolant 6 is directly or indirectly conveyed back to the container 7 via the bypass valve 15 so that the remaining volume flow, thus conveyed to the collecting pipe 4, corresponds to the desired total flow K.

[0084] At operating point AP3, the control device 12 can modify the temporary actuation state Z, for example, such that, although only the pump 8 is actuated (and therefore the bypass valve 15, if present, remains closed), a temporary operating pressure pAv is generated at the desired total flow K, which is greater than the maximum of the individual operating pressures pAa to pAd. In this case, the temporary operating pressure pAv is preferably set to the minimum of the possible and permissible values.

[0085] The following combination Figure 7 Explanation Figure 3 Another possible design of step S4. Figure 3 Step S4 is based on Figure 7 The design of the scheme is divided into steps S21 to S24. Figure 7 The operation mode and Figure 5 The operation mode can be combined with the Figure 5 In the case of a combination, step S21 can be omitted and steps S22 to S24 can be performed after step S13 or S14.

[0086] In step S21, the control device 12 (similar to Figure 5 Step S11) determines the rotational speed n of the pump 8 which is required to deliver the total flow K and simultaneously to bring about the required pressure increase δp from the suction pressure pS to the maximum working pressure of the determined individual working pressures pAa to pAd.

[0087] In step S22, the control device 12 checks whether actuation of the control valves 11a to 11d is permitted at the provisional operating pressure pAv determined in this manner. For example, the control device 12 can check whether the control speeds, which are changed by the actuation values Aa to Ad of the control valves 11a to 11b, comply with predetermined limits. This check thus includes a check for compliance with auxiliary conditions associated with the control valves.

[0088] It is possible (and even customary) that the auxiliary condition is met. In this case, the control device 12 goes to step S23. In step S23, the control device 12 does not take further measures. The determined rotational speed n can be used directly.

[0089] However, it is also possible (even if only rarely) that the auxiliary condition is not met, for example, if an excessively high control speed occurs. In this case, the control device 12 proceeds to step S24. In step S24, the control device 12 (depending on the individual case) can either tolerate the exceeding of a predetermined limit or adapt the temporary control state Z of the pump device 5. In particular, in some cases, an increase in the temporary operating pressure pAv can ensure that the predetermined limit is no longer exceeded, or at least only to a lesser extent, due to a corresponding change in the control of the control valves 11a to 11d.

[0090] The following combination Figure 8 Explanation Figure 3 A possible embodiment of step S5 , ie a possible way of determining the final actuation state Z using the temporary actuation state Z of the pump device 5 . Figure 3 Step S5 is based on Figure 8In the context of the embodiment of the present invention, step S41 replaces the control state Z. In step S41, the control device 12 considers at least one other control state (in addition to the provisional control state Z currently determined in step S4). This can be, for example, the immediately preceding final control state Z' or multiple preceding final control states Z'. For example, abrupt changes in the final control state Z' can be avoided by low-pass filtering or similar measures.

[0091] It is also possible to predict the setpoint flows Ka* to Kd* in a model-predictive manner over a forecast horizon of a plurality of cycle times (e.g., five, eight, or ten cycle times), and thus also to determine for the forecast horizon the temporary actuation state Z expected in the future of the pump device 5. In this case, the temporary actuation state Z expected in the future of the pump device 5 can also be included in the determination of the current final actuation state Z′.

[0092] In accordance with Figure 8 In the context of the embodiment of , it is possible to obtain a final working pressure pAe which is lower (even if usually only slightly lower) than the maximum working pressure of the individual working pressures pAa to pAd of steps S2 and S3. Figure 8 Within the scope of the design, it is advantageous if the limiting modulation value kLim of the control valves 11a to 11d is smaller than their maximum possible modulation factor and / or before taking into account other control states, a small offset is first added to the temporary working pressure pAv or the temporary working pressure pAv is scaled by a factor slightly greater than 1.

[0093] The present invention has been described above in conjunction with a design in which the pump device 5 has only a single pump 8. However, a design in which the pump device 5 has multiple pumps 8 is also possible without any problems. In this case, the pumps 8 must be controlled so that all pumps 8 are either completely blocked (blocked), so that they can be treated as if they were not present, or generate the same temporary operating pressure pAv and the same final operating pressure pAe. However, there is a degree of freedom in the distribution of the total flow K to the individual pumps 8. To address this degree of freedom, it is possible, for example, to distribute the total flow K to the pumps 8 evenly or proportionally to their capacities. Alternatively, it is possible to always actively operate only the minimum possible number of pumps 8. In this case, the manifold 4 is fed with a single pump 8, as appropriate. The next pump 8 is only switched on when the previously operated pump 8 can no longer deliver the required total flow K at the required temporary operating pressure pAv or the required final operating pressure pAe. In an analogous manner, the respective next pump 8 is only switched on when the previously operated pump 8 can no longer deliver the required total flow K at the required temporary operating pressure pAv or the required final operating pressure pAe.

[0094] The present invention has been described above with respect to a single cooling device 3. However, it is also possible for additional cooling devices 3 to be present. In this case, the additional cooling devices 3 can be controlled by the control device 12 or another control device as required. When controlled by the control device 12, the cooling devices 3 can be operated independently of each other.

[0095] The present invention offers numerous advantages. In particular, it results in significantly lower energy consumption. Compared to operating the cooling device 3 with a constant final working pressure pAe, savings of at least 25% and sometimes well over 80% are achieved. Even compared to an operating method in which the final working pressure pAe is individually adapted for each rolled product 2 and held constant only during the cooling of the respective rolled product 2, significant energy savings are still achieved. While it is theoretically conceivable that a reduction in the final working pressure pAe would lead to such a significant decrease in the efficiency of the pump device 5 that energy consumption would increase, this does not occur in practice. Furthermore, the mechanics of both the control valves 11a to 11d and the pump device 5 are protected. This is because it is generally beneficial for the control valves 11a to 11d to operate as wide open as possible. It is also beneficial for the pump device 5 to operate at the lowest possible speed. The cooling of the rolled product 2 itself should not be adversely affected.

[0096] Although the present invention has been illustrated and described in more detail by means of preferred embodiments, the present invention is not limited to the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the present invention.

[0097] Reference Signs List

[0098] 1 Rolling mill stand

[0099] 2 Rolled products

[0100] 3 Cooling device

[0101] 4 headers

[0102] 5 Pump unit

[0103] 6 Coolant

[0104] 7 Containers

[0105] 8 pumps

[0106] Branches 9a to 9d

[0107] 10a to 10d Application device

[0108] 11a to 11d Control valve

[0109] 12 Control Devices

[0110] 13 Computer Programs

[0111] 14 Machine Code

[0112] 15 Bypass valve

[0113] Aa to Ad control value

[0114] Amax Maximum control value

[0115] Amin minimum control value

[0116] API to AP3 working point

[0117] K Total flow

[0118] ka to kd modulation coefficient

[0119] Ka to Kd coolant flow rate

[0120] Ka* to Kd* Rated flow rate

[0121] kLim limit modulation value

[0122] KR reference coolant flow

[0123] KRmax Maximum reference coolant flow

[0124] KRmin minimum reference coolant flow rate

[0125] n Speed

[0126] nmax maximum speed

[0127] nmin minimum speed

[0128] pA, pAv, pAe working pressure

[0129] pAa to pAd Individual operating pressures

[0130] pR reference pressure

[0131] pS Suction pressure

[0132] Steps S1 to S41

[0133] Z, Z' control status

[0134] δp pressure increases.

Claims

1. A method for operating a cooling device (3) for cooling hot-rolled metal products (2), - wherein the cooling device (3) has a header (4) into which a fluid coolant (6) is fed by a pump device (5) and from which a plurality of branches (9a-9d) exit to the application device (10a-10d), - the pump device (5) comprises a plurality of pumps (8), a regulating valve (11a-11d) is arranged in each of the branches (9a-9d), and the fluid coolant (6) is applied to the hot rolled stock (2) by means of at least some of the application devices (10a-10d), wherein a setpoint flow (Ka*-Kd*) is known to the control device (12) of the cooling device (3), said setpoint flow being to be supplied to the application device (10a-10d), - wherein the control device (12) controls the pump device (5) as a function of a final control state (Z') and controls the regulating valves (11a-11d) as a function of control values (Aa-Ad), characterized in that In order to determine the final actuation state (Z') of the pump device (5) and the actuation values (Aa-Ad) of the regulating valves (11a-11d), the control device (12) - determining for the regulating valves (11a-11d) respective individual operating pressures (pAa-pAd) for the respective limiting modulation values (kLim) of the respective regulating valves (11a-11d), which must be present in the manifold (4) in order for the respective nominal flow (Ka*-Kd ) in their respective branches (9a -9d) flow, - determining a temporary control state (Z) of the pump device (5) so that a total flow rate (K) of the fluid coolant (6) is delivered to the manifold (4) by means of the pump device (5), the total flow rate corresponding to the sum of the set flow rates (Ka*-Kd*), and at the same time a temporary working pressure (pAv) prevails in the manifold (4), the temporary working pressure being at least as great as the maximum working pressure of the individual working pressures (pAa-pAd), - using the temporary actuation state (Z) of the pump device (5), determining a final actuation state (Z') of the pump device (5) such that a total flow rate (K) of the fluid coolant (6) is delivered to the manifold (4) by means of the pump device (5) and a final operating pressure (pAe) prevails in the manifold (4), and - using the final working pressure (pAe), determining the control values (Aa-Ad) of the control valves (11a-11d) so that the respective setpoint flow (Ka*-Kd*) flows in the respective branch (9a-9d).

2. The operating method according to claim 1, characterized in that: The limit modulation value (kLim) of the regulating valve (11a-11d) is the maximum modulation coefficient of the regulating valve (11a-11d) or is close to the maximum modulation coefficient of the regulating valve (11a-11d).

3. The operating method according to claim 1 or 2, characterized in that: In determining the temporary actuation state (Z), the control device (12) takes into account auxiliary conditions associated with the pump device (5).

4. The operating method according to claim 1 or 2, characterized in that: In determining the temporary actuation state (Z), the control device (12) takes into account auxiliary conditions associated with the regulating valves (11a-11d).

5. The operating method according to claim 1 or 2, characterized in that: In the context of determining a final control state (Z') of the pump device (5), the control device (12) additionally takes into account at least one previous final control state (Z') of the pump device (5) and / or at least one future expected temporary control state (Z) of the pump device (5).

6. A computer program product comprising a machine code (14) which can be executed by a control device (12) of a cooling device (3) for cooling a hot-rolled piece (2) made of metal, wherein the execution of the machine code (14) by the control device (12) causes the control device (12) to operate the cooling device (3) in accordance with the operating method according to any one of the preceding claims.

7. A control device for a cooling device (3) for cooling a hot-rolled sheet (2) made of metal, wherein the control device is programmed using a computer program contained in a computer program product according to claim 6, so that the control device operates the cooling device (3) according to the operating method according to any one of claims 1 to 5.

8. A cooling device for cooling a hot rolled piece (2) made of metal, - wherein the cooling device comprises a header (4), a pump device (5) and a plurality of application devices (10a-10d), - wherein a fluid coolant (6) is applied to the hot rolled stock (2) by means of at least some of the application devices (10a-10d), - wherein the application devices (10a-10d) are connected to the collecting pipe (4) via respective branches (9a-9d), - the pump device (5) comprises a plurality of pumps (8), by means of which the fluid coolant (6) is fed into the collecting pipe (4), - wherein regulating valves (11a-11d) are respectively arranged in said branches (9a-9d), The cooling device comprises a control device (12) according to claim 7, which operates the cooling device according to the operating method according to any one of claims 1 to 5.

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