EP3495056A1 - Improved control of water conservancy of a cooling section - Google Patents

Abstract

Hot rolled metal (3) is cooled in a cooling section. The cooling section has a pump (7) which takes coolant (2) from a coolant reservoir (8) and feeds it via a line system (9) to a number of coolant outlets (4, 6) which are upstream of the coolant outlets (4, 6) Valves (10) can be controlled. A control device (11) of the cooling section determines for a particular point in time, taking into account coolant flows (Wi) that are to be emitted via the coolant outlets (4, 6) at the respective point in time, in conjunction with a working pressure present on the inlet side of the valves (10) ( pA) of the coolant (2) control states (Ci) for the valves (10). It calculates a total coolant flow (WG) by summing the coolant flows (Wi). Taking into account the total coolant flow (WG), the working pressure (pA) of the coolant (2) and additionally a change (δWG) of the total coolant flow (WG), it determines a pump pressure (pP) that should prevail on the outlet side of the pump (7), so that the working pressure (pA) is reached on the inlet side of the valves (10). Taking into account the total coolant flow (WG), the pump pressure (pP) and a suction pressure (pS) on the inlet side of the pump (7), it determines a control state (CP) for the pump (7). It controls the valves (10) and the pump (7) according to the determined control states (Ci, CP). The control device (11) cyclically for these steps.

Description

Field of engineering

• wobei eine Steuereinrichtung der Kühlstrecke zyklisch für einen jeweiligen Zeitpunkt
  • -- unter Berücksichtigung von Kühlmittelströmen, die zu dem jeweiligen Zeitpunkt über die Kühlmittelauslässe abgegeben werden sollen, in Verbindung mit einem eingangsseitig der Ventile anstehenden Arbeitsdruck des Kühlmittels Ansteuerzustände für die Ventile ermittelt,
  • -- durch Summieren der Kühlmittelströme einen Gesamtkühlmittelstrom ermittelt,
  • -- unter Berücksichtigung des Gesamtkühlmittelstroms und des Arbeitsdrucks des Kühlmittels einen Pumpendruck ermittelt, der ausgangsseitig der Pumpe herrschen soll, so dass eingangsseitig der Ventile der Arbeitsdruck erreicht wird,
  • -- unter Berücksichtigung des Gesamtkühlmittelstroms, des Pumpendrucks und eines eingangsseitig der Pumpe herrschenden Saugdrucks einen Ansteuerzustand für die Pumpe ermittelt und
  • -- die Ventile und die Pumpe entsprechend den ermittelten Ansteuerzuständen ansteuert.

The present invention is based on an operating method for a cooling section for cooling hot metal stock, the cooling section having a pump which extracts coolant from a coolant reservoir and supplies via a line system to a number of coolant outlets, which are controlled via the coolant outlet upstream valves .

• wherein a control means of the cooling section cyclically for a respective time
  • taking into account coolant flows which are to be discharged via the coolant outlets at the respective time, in conjunction with a working pressure of the coolant present on the input side of the valves, determine activation states for the valves,
  • determining a total coolant flow by summing the coolant flows,
  • - Taking into account the total coolant flow and the working pressure of the coolant, a pump pressure is determined, which should prevail on the output side of the pump, so that the input side of the valves, the working pressure is reached,
  • - Considering the total coolant flow, the pump pressure and a suction side prevailing on the pump suction pressure determines a drive state for the pump and
  • - controls the valves and the pump according to the determined control states.

The present invention is further based on a computer program comprising machine code, which is provided by a control device is executable for a cooling line, wherein the processing of the machine code by the control device causes the control device operates the cooling section according to such an operating method.

The present invention is further based on a control device for a cooling section, wherein the control device is programmed with such a computer program, so that the control device operates the cooling section according to such an operating method.

• wobei die Kühlstrecke eine Pumpe aufweist, die aus einem Kühlmittelreservoir Kühlmittel entnimmt und über ein Leitungssystem einer Anzahl von Kühlmittelauslässen zuführt, die über den Kühlmittelauslässen vorgeordnete Ventile gesteuert werden,
• wobei die Kühlstrecke eine derartige Steuereinrichtung aufweist, welche die Kühlstrecke gemäß derartigen Betriebsverfahren betreibt.

The present invention is further based on a cooling section for cooling hot metal rolling stock,

• wherein the cooling section comprises a pump which extracts coolant from a coolant reservoir and supplies via a line system to a number of coolant outlets, which are controlled via the coolant outlet upstream valves,
• wherein the cooling section comprises such a control device which operates the cooling section according to such operating methods.

State of the art

The above items are for example from the WO 2013/143 925 A1 known. The WO 2014/124 867 A1 a similar disclosure can be found.

In cooling sections, rolled metal, in particular steel, is cooled after rolling. Examples of such cooling sections are the downstream of a hot strip mill cooling section with or without intensive cooling and the so-called Quette a plate mill. In particular, in one of the rolling mill downstream cooling section an exact temperature control is common. But even in the case of an arrangement within or in front of a rolling train - for example, between a roughing train and a finishing train - the defined and exact application of a desired amount of coolant is of great importance. Particularly in the case of cooling between a roughing train and a finishing train, due to the high volume requirement of coolant, particularly high demands are placed on the dynamics of the management of the coolant.

The coolant is usually water or at least substantially consists of water.

The amounts of water to be applied are considerable. In some cases, up to 20,000 m ³ / h must be applied to the hot rolling stock over a distance of only a few meters (for example 10 m to 20 m). For precise control of the cooling, it is not only necessary to timely and correctly control the valves of the cooling section. In addition, it is also necessary to provide the corresponding amounts of water on the inlet side of the valves and also to take them back again. The required control times often range around 1 second, in some cases even less than 1 second.

In some cases, it is possible to ensure the required dynamics of the water balance due to a corresponding mechanical design of the cooling section. For example, you can set up a water tank as a coolant reservoir in the immediate vicinity of the coolant outlets and supply the coolant outlets directly or booster pumps with water from the water tank. In this case, the line system between the coolant reservoir and the coolant outlets can be made sufficiently short. As a result, the required acceleration of the amount of water is possible without the accuracy of the cooling suffers to any significant extent.

In other cases, however, it is not possible to place a water tank in sufficient proximity to the coolant outlets. Sometimes there is only space outside the production hall for the installation of such a water tank. The pipe system for supplying the coolant outlets has in this case a much greater length, for example, about 100 m. It is even possible that no water tank can be installed at all. In this case, the piping system, which conveys the coolant to the coolant outlets, may have a length of several 100 m. If it is not possible to place a water tank sufficiently close to the coolant outlets, then changing the requested coolant quantity will require a larger amount of water - often several hundred tons - to be accelerated. This acceleration leads in the prior art to a delayed provision of the required amounts of coolant.

To solve this problem, various solutions are known in the art.

For example, from the WO 2014/032838 A1 it is known to provide by-pass coolant outlets in addition to payload coolant outlets via which the coolant is applied to the hot rolling stock. In this case, the coolant can be removed via the bypass coolant outlets without applying it to the hot rolling stock. When the hot material enters a cooling zone in which the coolant is to be applied to the hot material to be rolled, the bypass coolant outlets upstream valves are closed or closed, while at the same time the payload coolant outlets upstream valves are opened. In this way, the coolant that is moved through the piping system, only to a lesser extent or even not accelerated. The disadvantage of this approach, however, is that even then large amounts of coolant are pumped through the pipe system, if no hot rolling is to be cooled. Accordingly high are the energy consumption for the pump and the consumption of coolant.

Another known solution is to provide a riser with an overflow in the vicinity of the cooling area. A riser requires less space than a water tank. But it can save only a small amount of coolant. In this case, therefore, the maximum expected amount of coolant is continuously promoted to the cooling area. This already represents a disadvantage, since always the maximum amount of coolant required must be provided, while in a solution with a water tank only the average amount of water required must be provided. The height of the riser creates a nearly constant backpressure that is independent of the actual need for coolant. Again, the consumption of coolant and energy is correspondingly high, as always an unnecessarily large amount of coolant is provided. Furthermore, the pressure can not be adjusted. It always corresponds to the pressure resulting from the height of the column of coolant in the riser to the overflow.

The from the WO 2013/143 925 A1 Known approaches already represent a significant advance over these solutions. However, these solutions are still capable of improvement.

Summary of the invention

The object of the present invention is to provide possibilities by means of which the required amount of coolant can be provided in an efficient manner at any time with high accuracy, even without greater or lesser storage capability for coolant between the pump and the coolant outlets.

The object is achieved by an operating method with the features of claim 1. Advantageous embodiments are the subject of the dependent claims 2 to 12.

According to the invention, an operating method of the aforementioned type is configured in that the control device of the cooling section cyclically for the respective time in determining the pump pressure, which should prevail on the output side of the pump, not only the total coolant flow and the working pressure of the coolant taken into account, but in addition also takes into account a change in the total coolant flow. As a result, it is taken into account as a result of the pump pressure to what extent the amount of coolant in the line system has to be accelerated or decelerated. As a result, the respectively desired total coolant flow is achieved in a considerably more dynamic manner than in the prior art.

In a preferred embodiment, when determining the pump pressure, the control device takes into account a line resistance of the line system to be overcome by the total coolant flow. This results in an even higher accuracy in the determination of the pump pressure and thus the determination of the driving state of the pump.

In a particularly preferred embodiment of the present invention, in addition to the coolant streams which are to be discharged via the coolant outlets at the respective time, the control device is also known for a forecast horizon of predicted coolant flows which are to be discharged via the coolant outlets for a number of future times. In this case, it is possible that the control device takes into account the predicted coolant flows of at least one of the future points in time when determining the activation state of the pump.

In particular, it is possible for the control device to determine the associated total coolant flow for at least one future point in time and to take it into account when determining the change in the total coolant flow. In the simplest case, for example, the deviation from the total coolant flow for the respective time can be determined.

For even better results, it results if the control device continues to determine the change in the total coolant flow in addition to the predicted coolant flows of the at least one future point in time also takes into account the total coolant flow of at least one past time. In this case, the respective time is preferably in the middle between the at least one future time and the at least one past time.

In a particularly preferred embodiment, the coolant outlets comprise useful coolant outlets and bypass coolant outlets. In this case, the hot rolling stock is cooled exclusively by means of the coolant streams discharged via the useful coolant outlets. The bypass coolant outlets serve as a means to affect the overall flow of coolant without changing the coolant flows applied to the hot material. In the case of this embodiment, the control device determines, based on the to be discharged for the respective time and / or the future time points on the Nutz coolant outlets coolant flows to be delivered for the respective time and / or future times via the bypass coolant outlets coolant flows such that each total coolant flow maintained at an earlier point in time prior to the determination of the previous change in the total flow of refrigerant.

It can thereby be achieved that the time profile of the drive state of the pump has a relatively low dynamics. So it can be achieved a sufficiently "smooth" control of the pump. This increases the life of the pump and simplifies its control.

• für die zukünftigen Zeitpunkte anhand der jeweiligen prognostizierten Kühlmittelströme einen jeweiligen prognostizierten Gesamtkühlmittelstrom ermittelt,
• für die zukünftigen Zeitpunkte Änderungen der ermittelten Gesamtkühlmittelströme ermittelt und
• für den jeweiligen Zeitpunkt und/oder zukünftige Zeitpunkte innerhalb des Prognosehorizonts die jeweiligen Gesamtkühlmittelströme in Abhängigkeit vom Einhalten oder Überschreiten einer vorbestimmten Maximaländerung beibehält oder vorausschauend anpasst, so dass nach Möglichkeit sowohl die Änderung des Gesamtkühlmittelstroms für den jeweiligen Zeitpunkt als auch die Änderungen der ermittelten Gesamtkühlmittelströme für die zukünftigen Zeitpunkte die Maximaländerung einhalten.

Alternatively or in addition to the consideration of the predicted coolant flows of the at least one future time in determining the change in the total coolant flow, it is possible that the control device based on the forecast - if necessary - performs a predictive adjustment of the driving state of the pump. In particular, it is possible that the control device in the Determination of the activation state of the pump - ie the determination of the activation state, with which the pump is to be controlled at the respective time,

• determines a respective predicted total coolant flow for the future time points on the basis of the respective predicted coolant flows,
• for the future times changes in the calculated total coolant flows determined and
• for the respective time point and / or future time points within the forecast horizon, the respective total coolant flows as a function of maintaining or exceeding a predetermined maximum change or preemptively adapts, so that if possible both the change of the total coolant flow for the respective time as well as the changes of the determined total coolant flows for the future times comply with the maximum change.

This procedure corresponds to the usual procedure in the context of a model predictive control.

If a knowledge or prognosis of future total coolant flows is not possible, it is still possible to even out the control of the pump. In this case, as before, the coolant outlets include payload coolant outlets and bypass coolant outlets. The functionality of the corresponding coolant outlets is also as before. In this case, the control device determines the coolant flows to be delivered via the bypass coolant outlets such that coolant flows to be delivered via the bypass coolant outlets are as close as possible to a bypass target coolant flow and a change in the total amount to be delivered via the payload coolant outlets and the bypass coolant outlets Total coolant flow is as low as possible.

The valves may be in individual cases switching valves that can only assume two switching states, namely fully open and fully closed. Preferably, the However, valves stepless or at least in several stages controllable. Thus, there is preferably at least one intermediate position of the respective valve between "fully open" and "completely closed".

Preferably, the control device determines the working pressure such that the activation states of the valves maintain minimum distances to a minimum activation and a maximum activation and the activation state of the pump is kept constant as far as possible. As a result, the pump must be controlled with less dynamics.

In the context of determining the pump pressure, the control device preferably additionally takes into account a height difference to be overcome. The height difference represents a constant offset for the pump pressure.

Preferably, the control device additionally determines a control signal for a pump connected in parallel short-circuit valve and controls the short-circuit valve according to the determined control signal. As a result, operating states of the pump can be reached, which would be impossible or inadmissible without a short-circuit valve. The recirculated coolant flow via the short-circuit valve can be supplied as needed to the coolant reservoir or a connecting line between the coolant reservoir and the pump.

The object is further achieved by a computer program having the features of claim 13. According to the invention, the execution of the computer program by the control device causes the control device to operate the cooling path according to an operating method according to the invention.

The object is further achieved by a control device for a cooling section with the features of claim 14. According to the invention, the control device is programmed with a computer program according to the invention, so that the control device operates the cooling section according to an operating method according to the invention.

The object is further achieved by a cooling section for cooling of hot metal rolling with the features of claim 15. According to the invention, the cooling section has a control device according to the invention which operates the cooling section according to an operating method according to the invention. A cooling region of the cooling section, within which the coolant is applied to the hot rolling stock, can be arranged in particular within a rolling train and / or arranged upstream of a rolling train and / or downstream of the rolling train. The term "and / or" is to be understood in the sense that the cooling area can be arranged completely within the rolling train, completely downstream of the rolling train or partially disposed within the rolling train and partially downstream of the rolling train. Analogous designs apply to an arrangement in front of the rolling train.

Brief description of the drawings

FIG 1

eine Kühlstrecke,

FIG 2

ein Ablaufdiagramm,

FIG 3

eine Ventilkennlinie,

FIG 4

eine Pumpenkennlinie,

FIG 5

ein Zeitdiagramm,

FIG 6

ein Ablaufdiagramm,

FIG 7

ein Zeitdiagramm,

FIG 8

ein Ablaufdiagramm,

FIG 9

ein Pumpendiagramm,

FIG 10

eine Pumpe mit einem parallel geschalteten Kurzschlussventil und

FIG 11

eine Kühlstrecke.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which will be described in more detail in conjunction with the drawings. Here are shown in a schematic representation:

FIG. 1

a cooling section,

FIG. 2

a flow chart,

FIG. 3

a valve characteristic,

FIG. 4

a pump characteristic,

FIG. 5

a time diagram,

FIG. 6

a flow chart,

FIG. 7

a time diagram,

FIG. 8

a flow chart,

FIG. 9

a pump diagram,

FIG. 10

a pump with a parallel-connected short-circuit valve and

FIG. 11

a cooling section.

Description of the embodiments

According to FIG. 1 has a cooling section on a cooling area 1. Within the cooling region 1, a liquid coolant 2 - usually water - are applied to a hot rolling stock 3 and thereby the hot rolling 3 are cooled. The hot rolling stock 3 is made of metal, for example steel. For applying the liquid coolant 2 to the hot rolling stock 3, a number of useful coolant outlets 4 are arranged in the cooling area 1. The cooling area 1 is as shown in FIG FIG. 1 partially arranged within a rolling train. This is in FIG. 1 indicated that one of the Nutz-Kühlmittelauslässe 4 upstream of a last mill stand 5 of the rolling mill (for example, a finishing train) is arranged. However, the cooling area 1 could also be arranged completely within the rolling train. The cooling area 1 is also partially downstream of the rolling train. This is in FIG. 1 indicated that the other useful coolant outlets 4 are arranged downstream of the last rolling mill 5 of the rolling mill. However, the cooling area 1 could just as easily be arranged downstream of the rolling train. In the case of partial or complete readjustment, the cooling region 1 can be arranged, for example, between the last rolling stand 5 and a reel 5 '. Furthermore, it is also possible for the cooling region 1 to be arranged completely or partially upstream of the rolling train. This is in FIG. 1 and also the other figures are not shown.

In addition to the utility coolant outlets 4, bypass coolant outlets 6 are preferably still present. In FIG. 1 only a single such bypass coolant outlet 6 is shown. As a rule, only a single bypass coolant outlet 6 is present. In principle, however, a plurality of bypass coolant outlets 6 may also be present. Independently However, cooling of the hot rolling stock 3 takes place exclusively via the useful coolant outlets 4. Coolant 2, which is discharged via one of the bypass coolant outlets 6, does not serve to cool the hot rolling stock 3 Part of the coolant 2 via a collecting container 6 'collected and returned. The return of the coolant 2 from the collecting container 6 'is in FIG. 1 not shown.

The cooling section has a pump 7. The pump 7 can remove coolant 2 from a coolant reservoir 8, for example a water tank, and supply the coolant outlets 4, 6 via a line system 9. The term "pump" is used in the context of the present invention in a generic sense. Thus, the pump 7 may be a single pump or a plurality of pumps arranged one behind the other and / or in parallel.

Between the pump 7 and the coolant outlets 4, 6 valves 10 are arranged. By means of the valves 10, coolant flows Wi, which are discharged via the coolant outlets 4, 6, can be controlled. The index i stands, if it has the value 0, for the bypass coolant outlet 6, the associated coolant flow W0 thus for the coolant flow discharged via the bypass coolant outlet 6. In an analogous manner, the index i, if it has the value 1, 2, ... n, for each one of the Nutz coolant outlets 4, the associated coolant flow Wi so for the output over the respective Nutz-Kühlmittelauslass 4 coolant flow. The coolant flows Wi have the unit m ³ / s.

The cooling section has a control device 11, which operates the cooling section according to an operating method which will be explained in more detail below.

The control device 11 is generally designed as a software programmable control device. This is in FIG. 1 indicated that in the controller 11, the characters "μP" are drawn for microprocessor. The control device 11 is programmed with a computer program 12. The computer program 12 comprises machine code 13, which can be processed by the control device 11. The programming of the control device 11 with the computer program 12 (or, equivalently, the processing of the machine code 13 by the control device 11) causes the control device 11 to operate the cooling path according to the operating method explained below.

• In einem Schritt S1 wird der Steuereinrichtung 11 für einen jeweiligen Zeitpunkt für die Nutz-Kühlmittelauslässe 4 der jeweilige Kühlmittelstrom Wi bekannt. Der jeweilige Kühlmittelstrom Wi ist derjenige Kühlmittelstrom, der zu dem jeweiligen Zeitpunkt über den jeweiligen Nutz-Kühlmittelauslass 4 abgegeben werden soll.

Due to the programming with the computer program 12, the controller 11 performs the following in connection with FIG. 2 explained operating procedures:

• In a step S1, the controller 11 for a respective time for the Nutz coolant outlets 4, the respective coolant flow Wi known. The respective coolant flow Wi is that coolant flow which is to be discharged at the respective point in time via the respective useful coolant outlet 4.

In a step S2, the control device 11 determines the coolant flow W0. The coolant flow W0 is the coolant flow that is to be discharged at the respective time via the bypass coolant outlet 6. As a rule, the determination of the coolant flow W0 is effected as a function of the sum of the coolant flows Wi to be delivered via the useful coolant outlets 4. This will become apparent later.

In a step S3, the control device 11 forms by summing the coolant flows Wi a valid for the respective time total coolant flow WG.

In individual cases, it may happen that, in addition to the useful coolant outlets 4 and the bypass coolant outlet 6, further consumers are connected to the line system 9 are. In this case, the amount of coolant required by the other consumers in the determination of the total coolant flow WG must be taken into account. Often the other consumer is controlled by the control device 11, so that this is readily possible. Alternatively, it is possible to detect, for example, an actual variable, by means of which the current consumption of the further consumer can be determined. If no further information is available, the amount of coolant required by the other consumers can also be estimated.

In a step S4, the control device 11 determines a change δWG of the total coolant flow WG. The change δW of the total refrigerant flow WG indicates the extent to which the total refrigerant flow WG changes at each time point. It is therefore the derivation of the total coolant flow WG over time. In particular, the control device 11 can use a total coolant flow WG 'known from a previous cycle to determine the change ΔW of the total coolant flow WG.

In a step S5, the controller 11 updates the total refrigerant flow WG 'for the previous cycle. For example, it assumes the value for the total coolant flow WG, which it has determined in step S3.

In a step S6, the controller 11 sets a working pressure pA (unit: N / m ² ). The working pressure pA is the pressure that the coolant 3 on the input side of the valves 10 should have. It is possible that the working pressure pA of the control device 11 is predetermined. Alternatively, it is possible that the control device 11 independently determines the working pressure pA.

In a step S7, the control device 11 determines activation states Ci (with i = 0, 1,... N) for the valves 10. The activation states Ci can in particular be open positions of the valves 10.

bestimmt werden. In Gleichung 1 ist gi eine für das jeweilige Ventil 10 gültige Kennlinie. Die Kennlinie gi ist eine Funktion des jeweiligen Ansteuerzustands Ci. Sie gibt für einen Nenndruck pA0 an, wie groß bei einem bestimmten Ansteuerzustand Ci der über das jeweilige Ventil 10 fließende Kühlmittelstrom Wi jeweils ist. Dies ist in FIG 3 für ein einzelnes Ventil 10 rein exemplarisch dargestellt. Die Kennlinien gi der Ventile 10 können entweder aus Datenblättern der Hersteller der Ventile 10 entnommen werden oder experimentell ermittelt werden. Zur Ermittlung des jeweils erforderlichen Ansteuerzustands Ci kann die Steuereinrichtung beispielsweise Gleichung 1 nach Ci auflösen.The valves 10 are preferably steplessly stepless or at least in several stages. The flowing over the respective valve 10 coolant flow Wi can therefore according to the relationship $$\mathit{wi}=\mathit{gi}\left(\mathit{ci}\right)\cdot \sqrt{\mathit{pA}/\mathit{<figure-callout\; id="0"\; label="pA"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">pA</figure-callout>}0}$$

be determined. In Equation 1, gi is a characteristic valid for the respective valve 10. The characteristic curve gi is a function of the respective drive state Ci. It indicates, for a nominal pressure pA0, how great, at a certain activation state Ci, is the coolant flow Wi flowing through the respective valve 10. This is in FIG. 3 for a single valve 10 shown purely by way of example. The characteristic curves gi of the valves 10 can either be taken from data sheets of the manufacturers of the valves 10 or be determined experimentally. In order to determine the respectively required activation state Ci, the control device can, for example, solve equation (1) for Ci.

ermitteln. In Gleichung 2 ist pH ein (in der Regel konstanter) Druck, der durch eine Höhendifferenz H hervorgerufen wird. Die Höhendifferenz H wird zwischen der Ausgangsseite der Pumpe 7 und den Auslässen der Ventile 10 gemessen. Der Druck p1 beschreibt einen Druckabfall, der aufgrund der geförderten Gesamtkühlmittelstroms WG auf dem Weg von der Pumpe 7 zu den Ventilen 10 auftritt. Der Druck p1 beschreibt somit den Leitungswiderstand des Leitungssystems 9. Der Druck p1 ist eine - in der Regel nichtlineare - Funktion des Gesamtkühlmittelstroms WG. In den Druck p1 gehen, soweit erforderlich, auch zusätzliche Widerstände des Leitungssystems 9 wie beispielsweise Filterwiderstände und dergleichen mehr ein. Der Druck p2 ist eine Funktion der Änderung δWG des Gesamtkühlmittelstroms WG. Er errechnet sich wie folgt:

• Für die Beschleunigung des Kühlmittels 3 im Leitungssystem 9 wird nachfolgend davon ausgegangen, dass das Leitungssystem 9 über seine gesamte Länge L einheitlich einen Querschnitt A aufweist. Wenn dies nicht der Fall ist, muss die nachfolgende Betrachtung für die einzelnen Abschnitte des Leitungssystems 9 vorgenommen werden, die jeweils einen einheitlichen Querschnitt aufweisen.

In a step S8, the controller 11 determines a pump pressure pP. The pump pressure pP is that pressure which should prevail on the output side of the pump 7, so that the input side of the valves 10, the working pressure pA is reached. When determining the pump pressure pP, the control device 11 takes into account at least the total coolant flow WG, the working pressure pA and the change ΔW of the total coolant flow WG. For example, the controller 11 may set the pump pressure pP according to the relationship $$\mathit{pp}=\mathit{pA}+\mathit{pH}+\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">p</figure-callout>}1\left(\mathit{WG}\right)+\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}2\left(\mathit{\delta WG}\right)$$

determine. In Equation 2, pH is a (usually constant) pressure caused by a height difference H. The height difference H is measured between the output side of the pump 7 and the outlets of the valves 10. The pressure p1 describes a pressure drop due to the delivered total coolant flow WG on the way from the pump 7 to the valves 10 occurs. The pressure p1 thus describes the line resistance of the line system 9. The pressure p1 is a - generally non-linear - function of the total coolant flow WG. If necessary, additional resistances of the line system 9, such as, for example, filter resistances and the like, also enter the pressure p1. The pressure p2 is a function of the change δWG of the total coolant flow WG. It is calculated as follows:

• For the acceleration of the coolant 3 in the line system 9, it is assumed below that the line system 9 has a cross section A uniform over its entire length L. If this is not the case, the following consideration must be made for the individual sections of the line system 9, each having a uniform cross-section.

The amount of coolant 3 present in the line system 9 therefore results in AL, the mass m of the coolant 3 is ρAL, where ρ is the density of the coolant 3 (in the usual unit kg / m ³ ). The required acceleration a results in δWG / A. This results in the required force F to ma, ie the product of mass m and acceleration a. Thus, the required pressure p2 is F / A. Inserted into one another: $$\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}2=\frac{\rho \cdot L}{A}\cdot \mathit{\delta WG}$$

For this purpose, a numerical example: It is assumed that the line system 9 has a length L of 100 m and a cross-section A of 1 m ² . The coolant 3 is water. Within 1 second, the total coolant flow WG is to be increased from 2 m ³ / s to 2.5 m ³ / s. Then a pressure p2 of 50 kPa is required for the required acceleration of the amount of water in the line 9.

After determining the required pump pressure pP, the control device 11 determines in a step S9 an associated control state CP for the pump 7, so that the output side of the pump 7, the desired pump pressure pP is reached. When determining the control device 11 takes into account the pump pressure pP, the total coolant flow WG and a suction pressure pS, the input side of the pump 7 prevails. The suction pressure pS can be predetermined for the control device 11 or can be detected metrologically. It can, depending on the situation of the individual case, have a negative or a positive value or also the value 0. The control device 11 preferably uses a pump characteristic to determine the drive state CP for the pump 7. The pump characteristic sets the total coolant flow WG, the suction pressure pS on the input side of the pump 7 and the pump pressure pP on the output side of the pump 7 in relation to each other. The pump characteristic can, for example, as shown in FIG FIG. 4 as input parameters, the total coolant flow WG and the difference between the pump pressure pP and suction pressure pS have and deliver the associated control state CP as an output parameter. The drive state CP can be in particular the speed of the pump 7. Such characteristics are well known to those skilled in the art.

After the determination of all activation states Ci, CP, the control device controls the valves 10 and the pump 7 in a step S10 in accordance with the determined activation states Ci, CP.

From step S10, the controller 11 returns to step S1. The controller 11 thus executes the steps S1 to S10 cyclically, wherein the respective embodiment is valid for a respective time. Preferably, a strictly cyclical execution takes place, ie there is a fixed working cycle T, within which steps S1 to S10 are executed once each. The working cycle T can be, for example, 0.1 seconds to 1.0 seconds, preferably between 0.2 seconds and 0.5 seconds, in particular about 0.3 seconds.

ansetzen. WG' ist der Gesamtkühlmittelstrom des vorherigen Zeitpunkts. W0* ist ein für den Bypass-Kühlmittelauslass 6 vorgegebener Soll-Kühlmittelstrom. Er liegt vorzugsweise bei ca. 30 % bis ca. 70 % des maximalen Kühlmittelstroms für den Bypass-Kühlmittelauslass 6, insbesondere bei ca. 50 % dieses Wertes. α und β sind Wichtungsfaktoren. Sie sind nicht-negativ. Weiterhin kann - ohne Beschränkung der Allgemeinheit - gefordert werden, dass die beiden Wichtungsfaktoren α, β sich zu 1 summieren. Die Doppelstriche stehen für eine Norm. Bei der Norm kann es sich insbesondere um die übliche Quadratnorm handeln.In the simplest case, only the useful coolant flows Wi (i = 1, 2,... N) are known to the control device 11 for the respective point in time and for points in time before the respective point in time. Even in this case, the controller 11 may use the refrigerant flow W0 discharged through the bypass refrigerant outlet 6 to equalize the drive state CP of the pump 7. For this purpose, the control device 11, for example, a function F of the form $$F=\alpha \cdot \Vert {\displaystyle \underset{i=1}{\overset{n}{\Sigma }}}\mathit{wi}+W0-\mathit{WG}\text{'}\Vert +\beta \Vert W0-\mathrm{<figure-callout\; id="0"\; label="W"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">W</figure-callout>}0*\Vert$$

begin. WG 'is the total coolant flow of the previous time. W0 * is a predetermined coolant flow predetermined for the bypass coolant outlet 6. It is preferably about 30% to about 70% of the maximum coolant flow for the bypass coolant outlet 6, in particular about 50% of this value. α and β are weighting factors. They are not negative. Furthermore, without limiting the generality, it can be required that the two weighting factors α, β add up to 1. The double strokes stand for a standard. The standard may in particular be the usual square standard.

The coolant flows Wi for the Nutz coolant outlets 4 for the respective time are the controller 11 fixed. The function F thus has as the only freely selectable parameter to be delivered via the bypass coolant outlet 6 coolant flow W0. It is therefore possible to determine the minimum of the function F and to use as the coolant flow W0 for the bypass coolant outlet 6 the value at which this minimum results. As a result, it is achieved that the coolant flow W0 to be discharged via the bypass coolant outlet 6 is as close as possible to the bypass target coolant flow W0 * and the change in the total coolant flow WG is as small as possible.

Preferably, the control device 11, however, not only the coolant flows for the respective time and - based on the respective time - known for the past, but also for a forecast horizon PH projected Nutz coolant flows, ie those coolant flows, for a number of future times to be delivered via the Nutz coolant outlets 4. This is shown in FIG. 5 for the respectively resulting total coolant flows WG and a forecast horizon PH of (purely by way of example) four working cycles T. The term "forecast horizon" is furthermore not meant in the sense of how far the control device 11 actually has a prognosis. It only depends on how far the control device 11 utilizes the prognosis in the course of determining the activation states Ci, CP for the valves 10 and the pump 7. The forecast horizon PH may, for example, be in the range of 2 to 10 seconds. In general he should follow a strictly cyclical execution of the procedure of FIG. 2 correspond with several work cycles T.

In the event that the control device 11 is also aware of the predicted useful coolant flows, the control device 11 can determine the predicted useful coolant flows of at least one of the future points in determining the activation state C0 for the valve 10 controlling the bypass coolant outlet 6 and / or of the drive state CP of the pump 7. There are various possibilities for consideration here. Several of the options are explained below.

In order to explain the procedure, the coolant flows are subsequently provided with two indices. The first index (i) is - as before - for the respective coolant outlet 4, 6. The second index (j) stands for the time, with a value j = 0 stands for the respective time, a value j = 1 for the subsequent Time etc. In an analogous manner, the total coolant flows with the second index (j) are also Provided. For example, for the time indicated by the second index j = 2, Wi2 are the respective coolant flows for the individual coolant outlets 4, 6, while WG2 denotes the associated total coolant flow.

For example, it is possible for the control device 11 to determine the associated total coolant flow WGj (with j> 0) for at least one future point in time and to take this total coolant flow WGj into account in determining the change in the total coolant flow δWG. The corresponding total coolant flow WGj may in particular be the total coolant flow WG1 for the next point in time.

die Änderung des Gesamtkühlmittelstroms δWG ermitteln. Vorzugsweise berücksichtigt die Steuereinrichtung 11 bei der Ermittlung der Änderung δWG des Gesamtkühlmittelstroms jedoch zusätzlich zu den prognostizierten Nutz-Kühlmittelströmen Wij des mindestens einen zukünftigen Zeitpunkts weiterhin auch den Gesamtkühlmittelstrom WG' mindestens eines vergangenen Zeitpunkts. Der jeweilige Zeitpunkt sollte in der Mitte zwischen dem mindestens einen zukünftigen Zeitpunkt und dem mindestens einen vergangenen Zeitpunkt liegen. Insbesondere kann die Steuereinrichtung 11 die Änderung δWG des Gesamtkühlmittelstroms WG anhand der Beziehung $$\mathit{\delta WG}=\frac{\mathit{WG}1-\mathit{WG}\prime }{2T}$$

ermitteln. Bei dem Gesamtkühlmittelstrom WG' für den vergangenen Zeitpunkt kann es sich alternativ um einen Sollwert oder um einen Istwert handeln. Dies steht im Gegensatz zu den übrigen im vorliegenden Fall verwendeten variablen Größen, bei denen es sich stets um Sollwerte handelt.For example, the controller 11 for the respective time (j = 0) and the next time (j = 1) respectively, as described above, optimize the function F and thereby determine the associated total coolant flow WG0, WG1 and for each of the two mentioned times then on the basis of the relationship $$\mathit{\delta WG}=\frac{\mathit{WG}1-\mathit{WG}0}{T}$$

determine the change in the total coolant flow δWG. However, in determining the change δWG of the total coolant flow, the control device 11 preferably also takes into account the total coolant flow WG 'of at least one past time in addition to the predicted useful coolant flows Wij of the at least one future point in time. The respective time should be in the middle between the at least one future time and the at least one past time. Specifically, the controller 11 may determine the change δWG of the total refrigerant flow WG from the relationship $$\mathit{\delta WG}=\frac{\mathit{WG}1-\mathit{WG}\text{'}}{2T}$$

determine. The total coolant flow WG 'for the past point in time may alternatively be a desired value or an actual value. This is in contrast to the other variable variables used in the present case, which are always setpoints.

The procedure just described will be described below in connection with FIG. 6 detailed again.

FIG. 6 includes among others - analogous to FIG. 2 - Steps S6 to S10. These steps will therefore not be explained again below. However, the steps S1 to S5 are replaced by steps S11 to S15.

In step S11, the controller 11 - analogous to step S1 - for a respective time for the Nutz coolant outlets 4 of the respective coolant flow Wi0 known. In that regard, to the above comments FIG. 2 directed. In addition, however, the control device 11 will be aware of the respective coolant flows Wij (with j = 1, 2,..., M) for later points in time, that is to say for points in time which lie after the respective point in time, for the useful coolant outlets 4.

In step S12, the controller 11 determines the refrigerant flow W00. In particular, the coolant flow W00 results from the relationship $$W00=\mathit{WG}\text{'}-{\displaystyle \underset{i=1}{\overset{\mathrm{<figure-callout\; id="0"\; label="n\; wi"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">n\; </figure-callout>}}{\Sigma }}}\mathit{wi}\mathit{}0$$

It is thereby achieved that with respect to the change δWG of the total coolant flow WG0, the prognosis of the previous cycle is maintained. It is thus achieved that the total coolant flow WG0 of the current cycle coincides with the total coolant flow WG1 of the previous cycle. Thus, the total flow of coolant predicted in the previous cycle becomes maintained. This procedure is within the scope of FIG. 6 in which only the total coolant flow WG1 of the next cycle and the total coolant flow WG 'of the previous cycle are taken into account to determine the change δWG of the total coolant flow WG0. If necessary, analogous procedures can also be used for further total coolant flows WGj (with j> 1). In particular, the procedure can be adopted for each total coolant flow WGj, which was taken into account in a previous cycle in the course of determining the change δWG of the total coolant flow WG0 valid for the respective cycle. Thus, the coolant flows W0j are adjusted for the bypass coolant outlet 6 so as to be able to keep the total coolant flow WGj utilized during the previous cycle constant.

Furthermore, in step S12, the control device 11 determines the associated bypass coolant flow W0j for at least one operating cycle T for which the control device 11 knows the predicted useful coolant flows Wij. Within the concrete procedure of FIG. 6 For example, the controller 11 may determine the bypass refrigerant flow W01 by minimizing the following Equation 8: $$F=\alpha \cdot \Vert {\displaystyle \underset{i=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="n\; wi"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">n\; </figure-callout>}}{\Sigma }}}\mathit{wi}\mathit{}1+W01-\mathit{<figure-callout\; id="0"\; label="WG"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">WG</figure-callout>}0\Vert +\beta \Vert W01-\mathrm{<figure-callout\; id="0"\; label="W"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">W</figure-callout>}0*\Vert$$

The procedure is the same as explained above in connection with equation 4.

In a step S13, the controller 11 forms the respective total coolant flows WGj by summing the corresponding coolant streams Wij.

In step S14, the controller 11 determines the change ΔWG of the total refrigerant flow WG. The difference to step S4 of FIG. 2 is that the control device 11 in step S14 uses the relationship given above in equation 6.

In step S15, the controller 11 updates the total refrigerant flow WG 'for the previous cycle. The difference to step S5 of FIG. 2 is that the controller 11 in step S15 does not use the total coolant flow WG0 of the current cycle, but the total coolant flow WG1, which it has utilized in the context of determining the change δWG of the total coolant flow WG0.

Another way to take account of the projected Nutz coolant flows is described below in conjunction with FIG. 7 explained.

As already explained above, the control device 11 determines - see in FIG FIG. 6 the step S13 - for the respective time and after this time lying future time points in each case the associated total coolant flow WGj. FIG. 7 shows this for a prognosis horizon PH of four working cycles T. However, this prognosis horizon PH is of course only exemplary. The forecast horizon PH could also be larger or smaller. The determined total coolant flows WGj are in FIG. 7 indicated by small crosses.

FIG. 7 also shows the respective sum of the useful coolant flows Wij. This determination is readily possible within the framework of the forecast horizon PH, since the control device 11 knows the useful coolant flows Wij. The associated sums of the payload coolant streams Wij are in FIG. 7 indicated by small circles.

The control device 11 now further determines the associated changes in the total coolant flows WGj by forming the difference of directly consecutive total coolant flows WGj - for example, the total coolant flows WG1 and WG2. Then checks the controller 11 within the forecasting horizon PH, whether the determined changes the total coolant flows WGj each comply with a predetermined maximum change δmax or not. If the total coolant flows WGj comply with the maximum change δmax, the control device 11 retains the determined total coolant flows WGj. On the other hand, if the total coolant flows WGj do not comply with the maximum change Δmax, the control device 11 adapts the determined total coolant flows WGj in a forward-looking manner. The associated modified total coolant flows WGj are in FIG. 7 represented by small rectangles.

The adaptation is carried out as far as possible in such a way that both the change δWG of the total coolant flow WG0 for the respective point in time and the changes in the determined total coolant flows WGj for the future points in time comply with the maximum change δmax. This situation is in FIG. 7 shown.

As far as possible, the control device 11 retains the useful coolant flows Wij specified for the various times as part of the adaptation and adapts only the bypass coolant flows W0j. If compliance with the maximum change δmax can not be achieved with an adaptation of only the bypass coolant flows W0j, however, it is also necessary to adapt the useful coolant flows Wij.

Thus, based on the prognosis, a predictive predictive planning can take place. Not only can this, as in FIG. 7 shown to be required for an increase in the requested total coolant flows WGj, but also for a reduction of the requested total coolant flows WGj.

As part of the procedure according to FIG. 2 - The same applies to the procedure according to FIG. 6 - The working pressure pA is set once in step S6 and is then no longer changed. However, it is possible the procedure of FIG. 2 as modified in connection with FIG. 8 is explained. An analog modification is for the approach of FIG. 6 possible.

According to FIG. 8 There is a step S21 between steps S9 and S10. In step S21, the control device 11 checks whether the activation states Ci of the valves 10 comply with minimum distances to a minimum activation of the respective valve 10 and a maximum activation of the respective valve 10. Further, in step S21, the controller 11 checks to what extent the drive state CP of the pump 7 has been changed. For example, in the context of step S21, the control device 11 may set an optimization problem with boundary conditions to be observed. Such optimization problems are well known to those skilled in the art.

When the controller 11 determines in step S21 that the drive states Ci of the valves 10 keep the minimum clearances and the drive state CP of the pump 7 is kept constant as much as possible, the controller 11 proceeds to step S10. Otherwise, the controller 11 proceeds to a step S22. In step S22, the control device 11 varies the applied working pressure pA in the sense of said optimization.

The pump 7 has an allowable operating range. In particular, the operation of the pump 7 is as shown in FIG FIG. 9 only permissible between a minimum rotational speed nmin and a maximum rotational speed nmax. Furthermore, the required amount of coolant - ie the respective total coolant flow WG - must be between a minimum permissible coolant flow WGmin and a maximum permissible coolant flow WGmax. The minimum permissible coolant flow WGmin and the maximum permissible coolant flow WGmax are in this case as shown in FIG FIG. 9 depends on the difference between the pump pressure pP and the suction pressure pS. Without further action, the pump 7 can therefore only within the in FIG. 9 unhatched area operated.

However, it is possible for the pump 7 as shown in FIG FIG. 10 to switch a short-circuit valve 14 in parallel. Depending on the activation of the short-circuit valve 14, this makes it possible to divert between 0% and 100% of the coolant flow conveyed by the pump 7 via the short-circuit valve 14 and to return it to the inlet side of the pump 7 or to the coolant reservoir 8. As a result, only the remaining, non-recirculated portion remains as the total coolant flow WG. Thus, it is not only possible, the entirety of pump 7 and short-circuit valve 14 not only within the in FIG. 9 operate unhatched area. This would also be possible without the short-circuit valve 14. Rather, it is also possible due to the short-circuit valve 14, the entirety of pump 7 and short-circuit valve 14 within the in FIG. 9 cross-hatched area to operate. The determination of a control signal CK for the short-circuit valve 14 may, for example, in the context of step S9 (see FIG. 2 and FIG. 6 ) respectively. Of course, in this case, a corresponding activation of the short-circuit valve 14 by the control device 11 takes place in step S10.

Preferably, in the case of the embodiment according to FIG. 10 First, a check whether the pump 7 can be operated in a permissible range for itself. If this is the case, the short-circuit valve 14 remains (fully) closed. If this is not the case, the short-circuit valve 14 is opened as far as necessary to operate the pump 7 in a permissible range in itself.

The present invention has been explained above for a simple embodiment of the conduit system 9, namely as shown in FIG FIG. 1 for a single direct connection from the pump 7 to the valves 10, wherein the lengths of the individual stubs between a node 15 at which the stubs depart to the individual valves 10, and the Kühlmittelauslässen 4, 6 can be neglected.

However, the present invention is also applicable when the piping system 9 is made more complex. In this case, it only has to be taken into account that for each node at which a branch occurs, the sum of the coolant flows flowing into the respective node and flowing out from the respective node must result in a total of 0 and at the respective node for each connected section of the pipeline system 9 the same pressure must be given. The procedure is analogous to Kirchhoff's rules of electrical engineering. Although the procedure becomes more computationally complicated, the systematics remains unchanged.

The system remains unchanged even if 9 separate pumps are arranged in individual sections of the line system. This will be described below in connection with FIG. 11 explained in more detail by way of example.

According to FIG. 11 The line system 9 has three sections 16a, 16b, 16c. The portion 16a extends from a pump 7a to a node 15. It has the length La and the cross section Aa. From the node 15, the other two portions 16b, 16c extend to respective payload coolant outlets 4b, 4c and respective bypass coolant outlets 6b, 6c. In the section 16b is located just behind the node 15, a further pump 7b. The section 16b has a length Lb and a cross section Ab. There is no pump in section 16c. The section 16c has a length Lc and a cross section Ac. The coolant outlets 4b, 4c and 6b, 6c are each preceded by valves 10b, 10c. In the FIG. 11 shown configuration may occur, for example, in a cooling section, on the one hand an intensive cooling (coolant outlets 4b) and additionally a laminar cooling (coolant outlets 4c) and for each of the two cooling each bypass coolant outlet 6b, 6c. The hot rolling stock 3 and the arrangement of the Nutz-Kühlmittelauslässe 4b, 4c in the cooling area 1 are in FIG. 11 not pictured with FIG. 11 not to overload.

The driving states Cic of the valves 10c in the section 16c are shown in FIG $$\mathit{Wic}=\mathit{gic}\left(\mathit{cic}\right)\cdot \sqrt{\mathit{pAc}/\mathit{<figure-callout\; id="0"\; label="pA"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">pA</figure-callout>}0}$$

Wic are the respective coolant flows, gic is the respective valve characteristic, pAc the working pressure prevailing on the input side of the valves 10c. pA0 is, as already explained in connection with equation 1, a nominal pressure pA0. This results in the total coolant flow Wc for the section 16c $$\mathit{WC}=\Sigma \mathit{Wic}$$

p1c und p2c sind analog zu den Funktionen p1 und p2 definiert, jedoch auf den Abschnitt 16c bezogen. δWc ist die Änderung des Gesamtkühlmittelstroms Wc.From this follows, neglecting to be overcome height differences for the pressure p15 at node 15: $$\mathrm{<figure-callout\; id="15"\; label="p"\; filenames="imgf0001.png,imgf0008.png"\; state="\{\{state\}\}">p</figure-callout>}15=\mathit{pAc}+p1c\left(\mathit{WC}\right)+p2c\left(\mathit{\delta Wc}\right)$$

p1c and p2c are defined analogously to functions p1 and p2, but refer to section 16c. δWc is the change of the total coolant flow Wc.

In an analogous manner, the drive states Cib of the valves 10b in the section 16b result $$\mathit{wib}=\mathit{give}\left(\mathit{cib}\right)\cdot \sqrt{\mathit{pab}/\mathit{<figure-callout\; id="0"\; label="pA"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">pA</figure-callout>}0}$$

Wib are the respective coolant flows, gib is the respective valve characteristic, pAb the working pressure prevailing on the input side of the valves 10b. As before, pA0 is a nominal pressure pA0. This results in the total coolant flow Wb for the section 16b $$\mathit{wb}=\Sigma \mathit{wib}$$

p1b und p2b sind analog zu den Funktionen p1 und p2 definiert, jedoch auf den Abschnitt 16b bezogen. δWb ist die Änderung des Gesamtkühlmittelstroms Wb. Dadurch kann auch entsprechend $$\mathit{CPb}=\mathit{CPb}\left(\mathit{Wb},\mathit{pPb}-p15\right)$$

der erforderliche Ansteuerzustand CPb der Pumpe 7b ermittelt werden.From this follows - again neglecting to be overcome height differences - for the pump pressure pPb the output side of the pump 7b: $$\mathit{pPB}=\mathit{pab}+p1b\left(\mathit{wb}\right)+p2b\left(\mathit{\delta Wb}\right)$$

p1b and p2b are defined analogously to functions p1 and p2, but with reference to section 16b. δWb is the change of the total coolant flow Wb. This also allows accordingly $$\mathit{CPb}=\mathit{CPb}\left(\mathit{wb}.\mathit{pPB}-\mathrm{<figure-callout\; id="15"\; label="p"\; filenames="imgf0001.png,imgf0008.png"\; state="\{\{state\}\}">p</figure-callout>}15\right)$$

the required drive state CPb of the pump 7b can be determined.

The total coolant flow Wa flowing in section 16a is the sum of the total coolant flows Wb, Wc flowing in sections 16b and 16c: $$\mathit{Wa}=\mathit{wb}+\mathit{WC}$$

der erforderliche Pumpendruck pPa ausgangsseitig der Pumpe 7a ermittelt werden. p1a und p2a sind analog zu den Funktionen p1 und p2 definiert, jedoch auf den Abschnitt 16a bezogen. Anhand des Pumpendrucks pPa kann nun mittels der Beziehung $$\mathit{CPa}=\mathit{CPa}\left(\mathit{Wa},\mathit{pPa}-\mathit{pS}\right)$$

der Ansteuerzustand CPa der Pumpe 7a ermittelt werden.This can now be based on the relationship $$\mathit{pPa}=p16+p1a\left(\mathit{Wa}\right)+p2a\left(\mathit{\delta Wa}\right)$$

the required pump pressure pPa on the output side of the pump 7a can be determined. p1a and p2a are defined analogously to functions p1 and p2, but related to section 16a. Based on the pump pressure pPa can now by means of the relationship $$\mathit{CPa}=\mathit{CPa}\left(\mathit{Wa}.\mathit{pPa}-\mathit{pS}\right)$$

the drive state CPa of the pump 7a are determined.

Now, the working pressures pAb and pAc are target values of the system, which are given or possibly also by the Control device 11 can be determined. The total coolant flows Wb, Wc are known. For the determination of the changes δWb, δWc (and consequently also the change δWa) can be made to the above statements in connection with the FIG. 2 and 6 to get expelled. The equation system is thus clearly solvable.

The present invention has many advantages. In particular, the required coolant flows Wi, WG are provided with high accuracy without requiring a water tank or other compensatory measures. The working pressure pA can be selected as needed and even adjusted during operation of the cooling section. The operating range of the cooling section will be expanded. In particular, both the suction pressure pS and the pump pressure pP can be varied as needed. This applies both to pure laminar cooling and to pure intensive cooling as well as to a cooling section which comprises both laminar cooling and intensive cooling. Due to the adaptation of the working pressure pA and the pump pressure pP considerable energy can be saved. In a hot strip mill, the average energy consumption required to pump the coolant 2 can thereby be reduced by at least 30% over the prior art solutions, in some cases even by up to 50%. The associated cost savings can range well beyond € 100,000 a year. Furthermore, the process is extremely flexible. Within a few seconds, the total coolant flow WG can be increased from a minimum value to a maximum value or, conversely, reduced from the maximum value to the minimum value without the accuracy of the cooling suffers.

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

LIST OF REFERENCE NUMBERS

1

cooling area

2

coolant

3

rolling

4, 4b, 4c

Useful coolant outlets

5

rolling mill

5 '

reel

6, 6b, 6c

Bypass coolant outlet

6 '

receptacle

7, 7a, 7b

pump

8th

Coolant reservoir

9

line system

10, 10b, 10c

valves

11

control device

12

computer program

13

machine code

14

Short-circuit valve

15

junction

16a, 16b, 16c

Sections of the pipe system

A, Aa, Ab, Ac

Cross section of the pipe system

Ci, Cib, Cic

Control states of the valves

CP, CPa, CPb

Control states of pumps

F

function

gi, give, gic

Valve characteristics

H

height difference

i, j

indices

L, La, Lb, Lc

Length of the pipe system

nmin, nmax

speeds

p1, p1a to p1c p2, p2a to p2c

features

p15

print

pA, pAb, pAc

working pressures

pA0

nominal pressure

PH

forecast horizon

pP, pPa, pPb

pump pressures

pS

suction

S1 to S22

steps

T

power stroke

WG, WG ', WGj

Total flows of coolant

Wgmin, Wmax Wi, W0, Wij

Coolant flows

W0 *

Target coolant flow

α, β

Weighting factors

δWG, δWa, δWb, δ Wc

Change in total coolant flow

.delta..sub.max

maximum change

ρ

Density of the coolant

Claims (16)

Operating method for a cooling section for cooling hot rolled material (3) made of metal, wherein the cooling section comprises a pump (7) which takes coolant (2) from a coolant reservoir (8) and via a line system (9) a number of coolant outlets (4 6), the valves (10) upstream of the coolant outlets (4, 6) are controlled, - Wherein a control device (11) of the cooling section cyclically for a respective time - Taking into account coolant flows (Wi) to be delivered at the respective time via the coolant outlets (4, 6), in connection with an input side of the valves (10) pending working pressure (pA) of the coolant (2) Ansteuerzustände (Ci ) for the valves (10), - determined by summing the coolant flows (Wi) a total flow of coolant (WG), - Taking into account the total coolant flow (WG), the working pressure (pA) of the coolant (2) and additionally a change (δWG) of the total coolant flow (WG) determines a pump pressure (pP), the output side of the pump (7) prevail, so on the input side of the valves (10) the working pressure (pA) is reached, - Taking into account the total coolant flow (WG), the pump pressure (pP) and an inlet side of the pump (7) prevailing suction pressure (pS) determines a drive state (CP) for the pump (7) and - The valves (10) and the pump (7) according to the determined control states (Ci, CP) drives. Operating method according to claim 1,
characterized,
in that the control device (11), in determining the pump pressure (pP), takes into account a line resistance (p2) of the line system (9) to be overcome by the total coolant flow (WG). Operating method according to claim 1 or 2,
characterized,
in that the control device (11), in addition to the coolant flows (Wij) which are to be discharged via the coolant outlets (4, 6) at the respective time, are known for a forecast horizon (PH) of forecasted coolant flows (Wij) which are valid for a number of times future times via the coolant outlets (4, 6) to be delivered, and that the control device (11) the forecasted coolant flows (Wij) at least one of the future times in the determination of the driving state (CP) of the pump (7) into account. Operating method according to claim 3,
characterized,
that the control device (11) the respective total coolant flow for at least one future time (WGJ) is determined and in the determination of the change (δWG) takes into account the overall coolant flow (Wg0). Operating method according to claim 4,
characterized,
that the control device (11) in the determination of the change (δWG) of the total coolant flow (WG0) in addition to the predicted coolant flows (Wij) of the at least one future time further also considered the total coolant flow (WG ') of at least one past time and that the respective time in the middle between the at least one future time and the at least one past time. Operating method according to claim 4 or 5,
characterized, - in that the coolant outlets (4, 6) useful coolant outlets (4) and bypass coolant outlets (6) comprise, that the hot rolling stock (3) is cooled exclusively by means of the coolant streams (Wij) discharged via the useful coolant outlets (4), in that the control device (11), based on the coolant flows (Wij) to be delivered via the useful coolant outlets (4) for the respective point in time and / or future times, determines the bypass coolant outlets for the respective point in time and / or future times ( 6), so that each total refrigerant flow (WGj) taken into account at a previous time prior to the respective time is taken into account in determining the previous time change (δWG) of the total refrigerant flow (WG) becomes. Operating method according to one of Claims 3 to 6, characterized
in that the control device (11) determines the drive state (CP) of the pump (7). - determines a respective predicted total coolant flow (WGj) for the future time points on the basis of the respective predicted coolant flows (Wij), - For the future time changes of the determined total coolant flows (WGj) determined and - For the respective time and / or future time points within the forecast horizon (PH), the respective total coolant flows (WGj) in response to maintaining or exceeding a predetermined maximum change (δmax) maintains or anticipated adapts, so that if possible both the change of the total coolant flow (WG0 ) for the respective time as well as the changes of the determined total coolant flows (WGj) for the future times the maximum change (δmax) comply. Operating method according to claim 1 or 2,
characterized, - in that the coolant outlets (4, 6) useful coolant outlets (4) and bypass coolant outlets (6) comprise, - That the hot rolling stock (3) exclusively by means of the Nutz-Kühlmittelauslässe (4) discharged coolant flows (Wi) is cooled and - That the control device (11) via the bypass coolant outlets (6) to be discharged coolant flows (WO) determined such that the via the bypass coolant outlets (6) to be discharged coolant flows (WO) as close to a bypass target coolant flow (W0 *) and a change (δWG) of the total coolant flow (WG) to be delivered in total via the useful coolant outlets (4) and the bypass coolant outlets (6) is as small as possible. Operating method according to one of the above claims,
characterized,
that the valves (10) are steplessly or at least controlled in multiple stages. Operating method according to one of the above claims,
characterized,
that the control device (11), the working pressure (pA) is determined such that the driving conditions (Ci) of the valves (10) to comply with minimum distances from a minimum drive and a maximum driving and the driving state (CP) of the pump (7) is held as far as possible constant becomes. Operating method according to one of the above claims,
characterized,
that the control device (11) additionally takes into account a height difference (H) to be overcome during the determination of the pump pressure (pP). Operating method according to one of the above claims,
characterized,
that the control device (11) in addition a control signal (CK) for a pump (7) connected in parallel short-circuit valve (14) is determined and the short-circuit valve (14) controls in accordance with the control signal ascertained (CK). Computer program comprising machine code (13) which can be processed by a control unit (11) for a cooling line, wherein the execution of the machine code (13) by the control device (11) causes the control device (11) to simulate the cooling section according to an operating method operates one of the above claims. Control device for a cooling section, wherein the control device is programmed with a computer program (12) according to claim 13, so that the control device operates the cooling section according to an operating method according to one of claims 1 to 12. Cooling section for cooling hot metal (3) of metal, - wherein the cooling section comprises a pump (7) which removes coolant (2) from a coolant reservoir (8) and supplies via a line system (9) a number of coolant outlets (4, 6) which are located above the coolant outlets (4, 6) upstream valves (10) are controlled, - Wherein the cooling section has a control device (11) which operates the cooling section according to an operating method according to one of claims 1 to 12. Cooling section according to claim 15,
characterized,
is that a cooling region (1) of the cooling line, is applied to the hot rolled metal (3) within which the coolant (2) disposed within a rolling line and / or upstream of a rolling train and / or downstream of the rolling train.

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