EP3495056B1 - Improved control of water conservancy of a cooling section - Google Patents

Description

Field of technology

• 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 rolled metal, the cooling section having a pump which takes coolant from a coolant reservoir and supplies it via a line system to a number of coolant outlets which are controlled via valves upstream of the coolant outlets ,

• wherein a control device of the cooling section cyclically for a respective point in time
  • - taking into account the coolant flows that are to be emitted via the coolant outlets at the respective point in time, in connection with a working pressure of the coolant applied on the inlet side of the valves, control states are determined for the valves,
  • - Determines a total coolant flow by adding up 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 working pressure is reached on the input side of the valves,
  • - Taking into account the total coolant flow, the pump pressure and a suction pressure prevailing on the inlet side of the pump, a control state for the pump is determined and
  • - controls the valves and the pump according to the determined control states.

The present invention is further based on a computer program that includes machine code that is generated by a control device can be processed for a cooling section, the processing of the machine code by the control device causing the control device to operate the cooling section according to such an operating method.

The present invention is further based on a control device for a cooling section, the control device being 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 also based on a cooling section for cooling hot rolled metal,

• wherein the cooling section has a pump which takes coolant from a coolant reservoir and supplies it via a line system to a number of coolant outlets which are controlled via valves upstream of the coolant outlets,
• wherein the cooling section has 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. Of the WO 2014/124 867 A1 a similar disclosure can be found.

Rolled metal - in particular steel - is cooled in cooling sections after rolling. Examples of such cooling sections are the cooling section downstream of a hot strip mill, with or without intensive cooling, and the so-called Quette of a heavy plate mill. In particular, in a cooling section downstream of the rolling train, precise temperature control is common. But also 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, there are particularly high demands on the dynamics of the management of the coolant due to the large amount of coolant required.

The coolant is usually water or at least essentially 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 actuate the valves of the cooling section precisely and correctly in terms of time. It is also necessary to make the corresponding amounts of water available on the inlet side of the valves and also to take them back again. The control times required for this are often in the vicinity of 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, a water tank can be set up as a coolant reservoir in the immediate vicinity of the coolant outlets and the coolant outlets can be supplied with water from the water tank directly or via booster pumps. 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 cooling accuracy suffering 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 the space to set up such a water tank is only available outside the production hall. The line system for supplying the coolant outlets in this case has a considerably greater length, for example approx. 100 m. It is even possible that no water tank can be set up at all. In this case, the line system which conveys the coolant to the coolant outlets can have a length of several 100 m. If it is not possible to place a water tank close enough to the coolant outlets, larger amounts of water - often several 100 t - must first be accelerated when the requested coolant quantity is changed. In the prior art, this acceleration leads to a delayed provision of the required quantities of coolant.

Various solutions are known in the prior art for solving this problem.

For example, from the WO 2014/032 838 A1 known to provide bypass coolant outlets in addition to useful coolant outlets via which the coolant is applied to the hot rolling stock. In this case, the coolant can be discharged via the bypass coolant outlets without applying it to the hot rolling stock. When the hot rolling stock enters a cooling area in which the coolant is to be applied to the hot rolling stock, valves upstream of the bypass coolant outlets are retracted or closed, while valves upstream of the useful coolant outlets are opened at the same time. In this way, the coolant that is moved through the line system only needs to be accelerated to a lesser extent or even not at all. The disadvantage of this procedure, however, is that large amounts of coolant are pumped through the line system even when no hot rolling stock is to be cooled. The energy consumption for the pump and the consumption of coolant are correspondingly high.

Another known solution is to provide a riser pipe with an overflow near the cooling area. A riser pipe takes up less space than a water tank. But it can only store a small amount of coolant. In this case, the maximum amount of coolant to be expected is therefore continuously delivered to the cooling area. This already represents a disadvantage, since the maximum required amount of coolant always has to be provided, while in a solution with a water tank, only the average required amount of water has to be provided. The height of the riser creates an almost constant back pressure that is independent of the specific coolant requirement. Here, too, the consumption of coolant and energy is correspondingly high, since an unnecessarily large amount of coolant is always provided. Furthermore, the pressure cannot be adjusted. It always corresponds to the pressure resulting from the height of the column of coolant in the riser pipe up to the overflow.

The ones from the WO 2013/143 925 A1 Known procedures already represent a considerable advance compared to these solutions. However, these solutions can still be improved.

Summary of the invention

The object of the present invention is to create possibilities by means of which the required amount of coolant can be made available efficiently at any time with high accuracy, even without a larger or smaller storage facility for coolant between the pump and the coolant outlets.

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

According to the invention, an operating method of the type mentioned at the beginning is designed in that the control device of the cooling section cyclically takes into account not only the total coolant flow and the working pressure of the coolant, but additionally for the respective point in time when determining the pump pressure that should prevail on the output side of the pump a change in the total coolant flow is also taken into account. As a result, the pump pressure takes into account the extent to which 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 much 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 that has to be overcome by the total coolant flow. This results in even greater accuracy in determining the pump pressure and thus in determining the control state of the pump.

In a particularly preferred embodiment of the present invention, in addition to the coolant flows that are to be released via the coolant outlets at the respective point in time, the control device knows the forecasted coolant flows for a forecast horizon that are to be released for a number of future times via the coolant outlets. In this case it is possible for the control device to take into account the predicted coolant flows of at least one of the future points in time when determining the control state of the pump.

In particular, it is possible that the control device determines the associated total coolant flow for at least one future point in time and takes 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 can be determined for the respective point in time.

It leads to even better 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 from at least one previous point in time. In this case, the respective point in time is preferably in the middle between the at least one future point in time and the at least one past point in 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 flows emitted via the useful coolant outlets. The bypass coolant outlets serve as a means of influencing the overall coolant flow without changing the coolant flows applied to the hot rolling stock. In the case of this embodiment, based on the coolant flows to be dispensed via the useful coolant outlets for the respective point in time and / or the future points in time, the control device determines the coolant flows to be dispensed via the bypass coolant outlets for the respective point in time and / or the future points in time in such a way that each total coolant flow that was taken into account at an earlier point in time before the respective point in time when determining the change in the total coolant flow valid for the earlier point in time is retained.

As a result, it can be achieved that the time profile of the control state of the pump has a relatively low dynamic. A sufficiently "smooth" control of the pump can therefore be achieved. This increases the service 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.

As an alternative or in addition to taking into account the predicted coolant flows of the at least one future point in time when determining the change in the total coolant flow, it is possible for the control device to use the forecast - if necessary - to carry out a predictive adjustment of the control state of the pump. In particular, it is possible that the control device in the Determination of the control state of the pump - i.e. the determination of the control state with which the pump is to be controlled at the respective point in time, -

• for the future times based on the respective forecast coolant flows, a respective forecast total coolant flow is determined,
• for the future times changes in the total coolant flows determined are determined and
• maintains or anticipates the respective total coolant flows for the respective point in time and / or future points in time within the forecast horizon depending on whether a predetermined maximum change is adhered to or exceeded, so that, if possible, both the change in the total coolant flow for the respective point in time and the changes in the total coolant flows determined for the future times adhere to the maximum change.

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

If it is not possible to know or forecast future total coolant flows, it is still possible to make the control of the pump more uniform. In this case, the coolant outlets include useful coolant outlets and bypass coolant outlets, as before. The functionality of the corresponding coolant outlets is also as before. In this case, the control device determines the coolant flows to be dispensed via the bypass coolant outlets in such a way that the coolant flows to be dispensed via the bypass coolant outlets are as close as possible to a desired bypass coolant flow and a change in the total coolant flow to be dispensed via the useful coolant outlets and the bypass coolant outlets Total coolant flow is as low as possible.

In individual cases, the valves can be switching valves which can only assume two switching states, namely fully open and fully closed. Preferably they are Valves can be controlled steplessly or at least in several steps. There is therefore preferably at least one intermediate position of the respective valve between "completely open" and "completely closed".

The control device preferably determines the working pressure in such a way that the control states of the valves adhere to minimum distances from minimum control and maximum control and the control state of the pump is kept constant as far as possible. This means that the pump must be controlled with less dynamics.

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

The control device preferably also determines a control signal for a short-circuit valve connected in parallel with the pump and controls the short-circuit valve in accordance with the determined control signal. As a result, operating states of the pump can be achieved that would be impossible or inadmissible without a short-circuit valve. The coolant flow returned via the short-circuit valve can be fed to the coolant reservoir or a connecting line between the coolant reservoir and the pump as required.

The object is also achieved by a computer program with the features of claim 13. According to the invention, the processing of the computer program by the control device causes the control device to operate the cooling section according to an operating method according to the invention.

The object is also achieved by a control device for a cooling section having 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 also achieved by a cooling section for cooling hot rolled metal 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 area of the cooling section, within which the coolant is applied to the hot rolling stock, can in particular be arranged within a rolling train and / or upstream of a rolling train and / or downstream of the rolling train. The term “and / or” is to be understood here in the sense that the cooling area can be arranged completely within the rolling train, can be arranged completely downstream of the rolling train or can be arranged partially within the rolling train and partially downstream of the rolling train. Analogous statements 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 properties, features and advantages of this invention as well as the manner in which they are achieved will become more clearly and clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings. Here show in a schematic representation:

FIG 1

a cooling section,

FIG 2

a flow chart,

FIG 3

a valve characteristic,

FIG 4

a pump curve,

FIG 5

a timing diagram,

FIG 6

a flow chart,

FIG 7

a timing diagram,

FIG 8

a flow chart,

FIG 9

a pump diagram,

FIG 10

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

FIG 11

a cooling section.

Description of the embodiments

According to FIG 1 a cooling section has a cooling area 1. Within the cooling area 1, a liquid coolant 2 - usually water - can be applied to a hot rolling stock 3 and the hot rolling stock 3 can be cooled as a result. The hot rolling stock 3 consists of metal, for example steel. To apply the liquid coolant 2 to the hot rolling stock 3, a number of useful coolant outlets 4 are arranged in the cooling region 1. The cooling area 1 is as shown in FIG 1 partially arranged within a rolling train. This is in FIG 1 indicated by the fact that one of the useful coolant outlets 4 is arranged upstream of a last roll stand 5 of the rolling train (for example a finishing train). The cooling area 1 could, however, also be arranged completely within the rolling train. The cooling area 1 is still partially downstream of the rolling train. This is in FIG 1 indicated by the fact that the other useful coolant outlets 4 are arranged downstream of the last rolling stand 5 of the rolling train. However, the cooling area 1 could just as completely be arranged downstream of the rolling train. In the case of partial or complete rearrangement, the cooling area 1 can, for example, be arranged between the last roll stand 5 and a reel 5 '. Furthermore, it is also possible that the cooling area 1 is arranged completely or partially upstream of the rolling train. This is in FIG 1 and also not shown in the other figures.

In addition to the useful coolant outlets 4, bypass coolant outlets 6 are preferably also present. In FIG 1 only a single such bypass coolant outlet 6 is shown. As a rule, there is also only a single bypass coolant outlet 6. In principle, however, several bypass coolant outlets 6 can also be present. Independently of the number of bypass coolant outlets 6, however, the hot rolling stock 3 is cooled 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. For example, this can Part of the coolant 2 can be collected and returned via a collecting container 6 '. The return of the coolant 2 from the collecting container 6 'is shown in FIG FIG 1 not shown.

The cooling section has a pump 7. The pump 7 can take coolant 2 from a coolant reservoir 8 - for example a water tank - and feed it to the coolant outlets 4, 6 via a line system 9. The term “pump” is used in the generic sense in the context of the present invention. The pump 7 can therefore be a single pump or several pumps arranged one behind the other and / or in parallel.

Valves 10 are arranged between the pump 7 and the coolant outlets 4, 6. By means of the valves 10, coolant flows Wi, which are emitted via the coolant outlets 4, 6, can be controlled. The index i, if it has the value 0, stands for the bypass coolant outlet 6, and the associated coolant flow W0 thus stands for the coolant flow output via the bypass coolant outlet 6. In an analogous manner, the index i, if it has the value 1, 2, ... n, stands for one of the useful coolant outlets 4, the associated coolant flow Wi thus for the coolant flow emitted via the respective useful coolant outlet 4. 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 that is explained in more detail below.

The control device 11 is generally designed as a software-programmable control device. This is in FIG 1 indicated by the fact that the characters "μP" for microprocessor are drawn in the control device 11. 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 section according to the operating method explained below.

Due to the programming with the computer program 12, the control device 11 carries out the following in connection with FIG 2 explained operating procedures from:
In a step S1, the control device 11 becomes aware of the respective coolant flow Wi for a respective point in time for the useful coolant outlets 4. The respective coolant flow Wi is that coolant flow which is to be emitted via the respective useful coolant outlet 4 at the respective point in time.

In a step S2, the control device 11 determines the coolant flow W0. The coolant flow W0 is that coolant flow which is to be emitted via the bypass coolant outlet 6 at the respective point in time. As a rule, the coolant flow W0 is determined as a function of the sum of the coolant flows Wi to be emitted via the useful coolant outlets 4. This will become apparent from later explanations.

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

In individual cases it can 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 must be taken into account when determining the total coolant flow WG. Often the other consumer is also controlled by the control device 11, so that this is easily possible. Alternatively, it is possible, for example, to record an actual variable, on the basis of which the current consumption of the additional 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 in the total coolant flow WG. The change δW of the total coolant flow WG indicates the extent to which the total coolant flow WG changes at the respective point in time. It is therefore a matter of deriving the total coolant flow WG over time. In order to determine the change δW in the total coolant flow WG, the control device 11 can in particular use a total coolant flow WG 'which it knows from a previous cycle.

In a step S5, the control device 11 updates the total coolant flow WG 'for the previous cycle. For example, it takes over the value for the total coolant flow WG that it determined in step S3.

In a step S6, the control device 11 defines a working pressure pA (unit: N / m ² ). The working pressure pA is that pressure which the coolant 3 should have on the inlet side of the valves 10. It is possible that the working pressure pA of the control device 11 is specified. Alternatively, it is possible for the control device 11 to independently determine the working pressure pA.

In a step S7, the control device 11 determines control states Ci (with i = 0, 1,... N) for the valves 10. The control states Ci can in particular be the 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 can preferably be controlled continuously or at least in several steps. The coolant flow Wi flowing through the respective valve 10 can therefore according to the relationship $$\mathit{Wi}=\mathit{gi}\left(\mathit{Ci}\right)\cdot \sqrt{\mathit{pA}/\mathit{<figure-callout\; id="0"\; label="pA"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">pA</figure-callout>}0}$$

to be determined. In equation 1, gi is a characteristic curve that is valid for the respective valve 10. The characteristic curve gi is a function of the respective control state Ci. For a nominal pressure pA0, it indicates how large the coolant flow Wi flowing through the respective valve 10 is in each case for a specific control state Ci. This is in FIG 3 shown purely by way of example for a single valve 10. The characteristic curves gi of the valves 10 can either be taken from data sheets of the manufacturers of the valves 10 or determined experimentally. To determine the respectively required control 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:In a step S8, the control device 11 determines a pump pressure pP. The pump pressure pP is that pressure which 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. 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 in the total coolant flow WG. For example, the control device 11 can adjust the pump pressure pP according to the relationship $$\mathit{pp}=\mathit{pA}+\mathit{pH}+\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}1\left(\mathit{Flat\; share}\right)+\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}2\left(\mathit{\delta WG}\right)$$

determine. In equation 2, pH is a (usually constant) pressure that is caused by a height difference H. The height difference H is measured between the outlet side of the pump 7 and the outlets of the valves 10. The pressure p1 describes a pressure drop that occurs due to the total coolant flow WG conveyed 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 filter resistances and the like, also enter into the pressure p1. The pressure p2 is a function of the change δWG in 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 uniform cross section A 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, which each have a uniform cross section.

Hierzu ein Zahlenbeispiel: Man nehme an, das Leitungssystem 9 weise eine Länge L von 100 m und einen Querschnitt A von 1 m² auf. Das Kühlmittel 3 sei Wasser. Binnen 1 Sekunde soll der Gesamtkühlmittelstrom WG von 2 m³/s auf 2,5 m³/s erhöht werden. Dann ist für die erforderliche Beschleunigung der im Leitungssystem 9 befindlichen Wassermenge ein Druck p2 von 50 kPa erforderlich.The amount of coolant 3 located in the line system 9 results in AL, the mass m of the coolant 3 in pAL, where ρ is the density of the coolant 3 (in the usual unit kg / m ³ ). The required acceleration a results from δWG / A. This results in the required force F to ma, i.e. the product of mass m and acceleration a. The required pressure p2 is thus F / A. Inserted into each other, the following applies: $$\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}2=\frac{\rho \cdot \mathrm{L.}}{\mathrm{A.}}\cdot \mathit{\delta WG}$$

Here is a numerical example: Assume 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. The total coolant flow WG should be increased from 2 m ³ / s to 2.5 m ³ / s within 1 second. A pressure p2 of 50 kPa is then required for the required acceleration of the amount of water in the line system 9.

After the required pump pressure pP has been determined, the control device 11 determines an associated control state CP for the pump 7 in a step S9, so that the desired pump pressure pP is reached on the output side of the pump 7. When determining, the control device 11 takes into account the pump pressure pP, the total coolant flow WG and a suction pressure pS that prevails on the inlet side of the pump 7. The suction pressure pS can be specified for the control device 11 or can be recorded by measurement. It can have a negative or a positive value or the value 0, depending on the situation of the individual case. The control device 11 preferably uses a pump characteristic curve to determine the control state CP for the pump 7. The pump characteristic sets the total coolant flow WG, the suction pressure pS on the inlet side of the pump 7 and the pump pressure pP on the outlet side of the pump 7 in relation to one another. The pump characteristic can, for example, as shown in FIG 4 have the total coolant flow WG and the difference between pump pressure pP and suction pressure pS as input parameters and supply the associated control state CP as output parameters. The control state CP can in particular be the speed of the pump 7. Such characteristics are generally known to those skilled in the art.

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

From step S10, the control device 11 goes back to step S1. The control device 11 executes the steps S1 to S10 cyclically, the respective execution being valid for a respective point in time. A strictly cyclical execution preferably takes place, ie there is a fixed work cycle T within which steps S1 to S10 are each processed once. The work 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) for the respective point in time and for points in time prior to the respective point in time are known to the control device 11. Even in this case, the control device 11 can use the coolant flow W0 released via the bypass coolant outlet 6 to equalize the control state CP of the pump 7. For this purpose, the control device 11 can, for example, have a function F of the form $$\mathrm{F.}=\alpha \cdot \Vert {\displaystyle \sum _{i=1}^n\mathit{Wi}+\mathrm{W.}0-\mathit{Flat\; share}\prime }\Vert +\beta \Vert \mathrm{W.}0-\mathrm{W.}{0}^{\ast }\Vert$$

apply. WG 'is the total coolant flow from the previous point in time. W0 * is a setpoint coolant flow specified 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. You are not negative. Furthermore - without restricting the generality - it can be required that the two weighting factors α, β add up to 1. The double lines stand for a standard. The norm can in particular be the usual square norm.

The coolant flows Wi for the useful coolant outlets 4 for the respective point in time are predetermined for the control device 11. The function F thus has the coolant flow W0 to be emitted via the bypass coolant outlet 6 as the only freely selectable parameter. It is therefore possible to determine the minimum of the function F and to use that value as the coolant flow W0 for the bypass coolant outlet 6 at which this minimum results. The result is 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, however, not only the coolant flows for the respective point in time and - based on the respective point in time - for the past are known to the control device 11, but also useful coolant flows forecast for a forecast horizon PH, i.e. those coolant flows that are for a number of future points in time to be delivered via the useful coolant outlets 4. This is shown in FIG 5 for the 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 still not meant in the sense of how far the control device 11 is actually aware of a forecast. It only depends on how far the control device 11 utilizes the prognosis in the course of determining the control states Ci, CP for the valves 10 and the pump 7. The forecast horizon PH can be in the range from 2 to 10 seconds, for example. In general, if the procedure of FIG 2 correspond to several work cycles T.

In the event that the control device 11 also knows the forecast useful coolant flows, the control device 11 can use the forecast useful coolant flows at least one of the future points in time when determining the control state C0 for the valve 10 and / or controlling the bypass coolant outlet 6 the control state CP of the pump 7. There are various options for taking this into account. Several of the possibilities are explained below.

In order to illustrate the procedure, the coolant flows are given two indices below. The first index (i) stands - as before - for the respective coolant outlet 4, 6. The second index (j) stands for the point in time, with a value j = 0 for the respective point in time and a value j = 1 for the subsequent one Point in time, etc. In an analogous manner, the total coolant flows with the second index (j) Mistake. For example, for the point in time denoted 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 that the control device 11 determines the associated total coolant flow WGj (with j> 0) for at least one future point in time and takes this total coolant flow WGj into account when determining the change in the total coolant flow δWG. The corresponding total coolant flow WGj can 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 control device 11 can optimize the function F for the respective point in time (j = 0) and the next point in time (j = 1), as explained above, and thereby determine the associated total coolant flow WG0, WG1 for the two times mentioned then based on the relationship $$\mathit{\delta WG}=\frac{\mathit{Flat\; share}1-\mathit{Flat\; share}0}{T}$$

determine the change in the total coolant flow δWG. When 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 previous point in time in addition to the forecast useful coolant flows Wij of the at least one future point in time. The respective point in time should lie in the middle between the at least one future point in time and the at least one past point in time. In particular, the control device 11 can determine the change δWG in the total coolant flow WG on the basis of the relationship $$\mathit{\delta WG}=\frac{\mathit{Flat\; share}1-\mathit{Flat\; share}\prime }{2T}$$

determine. The total coolant flow WG 'for the past point in time can alternatively be a setpoint 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 discussed is described below in connection with FIG 6 presented again in detail.

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

In step S11, the control device 11 - analogously to step S1 - is aware of the respective coolant flow Wi0 for a respective point in time for the useful coolant outlets 4. In this respect, the above explanations apply FIG 2 referenced. In addition, however, the control device 11 knows the respective coolant flows Wij (with j = 1, 2,... M) for the useful coolant outlets 4 for later points in time, that is to say for points in time that lie after the respective point in time.

In step S12, the control device 11 determines the coolant flow W00. In particular, the coolant flow W00 results from the relationship $$\mathrm{W.}00=\mathit{Flat\; share}\prime -{\displaystyle \sum _{i=1}^{\mathrm{<figure-callout\; id="0"\; label="n\; Wi"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">n\; </figure-callout>}}\mathit{Wi}\mathit{}0}$$

This ensures that the forecast of the previous cycle is adhered to with regard to the change δWG in the total coolant flow WG0. It is thus achieved that the total coolant flow WG0 of the current cycle corresponds to the total coolant flow WG1 of the previous cycle. So the total coolant flow forecast in the previous cycle becomes maintained. This approach is part 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 taken for each total coolant flow WGj which was taken into account in a previous cycle in the context of determining the change δWG in the total coolant flow WG0 that is valid for the respective cycle. The coolant flows W0j for the bypass coolant outlet 6 are therefore adapted in order to be able to keep the total coolant flow WGj, which was utilized in the course of the previous cycle, constant.

Furthermore, in step S12, the control device 11 determines the associated bypass coolant flow W0j for at least one work cycle T, for which the control device 11 knows the predicted useful coolant flows Wij. As part of the concrete approach of FIG 6 For example, the control device 11 can determine the bypass coolant flow W01 by minimizing the following equation 8: $$\mathrm{F.}=\alpha \Vert {\displaystyle \sum _{i=1}^{\mathrm{<figure-callout\; id="1"\; label="n\; Wi"\; filenames="imgf0003.png"\; state="\{\{state\}\}">n\; </figure-callout>}}\mathit{Wi}\mathit{}1+\mathrm{W.}01-\mathit{<figure-callout\; id="0"\; label="Flat\; share"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">Flat\; share</figure-callout>}0}\Vert +\beta \Vert \mathrm{W.}01-\mathrm{W.}{0}^{\ast }\Vert$$

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

In a step S13, the control device 11 forms the corresponding total coolant flows WGj by adding up the corresponding coolant flows Wij.

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

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

Another possibility for taking into account the forecast useful coolant flows is described below in connection with FIG 7 explained.

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

FIG 7 also shows the respective sum of the useful coolant flows Wij. This determination is easily 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 useful coolant flows Wij are in FIG 7 indicated by small circles.

The control device 11 now also determines the associated changes in the total coolant flows WGj by forming the difference between the total coolant flows WGj that follow one another directly - for example the total coolant flows WG1 and WG2. The control device 11 then checks within the forecast horizon PH whether the changes determined of 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 maintains the determined total coolant flows WGj. If, on the other hand, the total coolant flows WGj do not adhere to the maximum change δmax, the control device 11 adjusts the determined total coolant flows WGj in advance. The associated modified total coolant flows WGj are shown in FIG 7 represented by small rectangles.

The adaptation takes place, if possible, in such a way that both the change δWG in 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 predetermined for the different points in time within the scope of the adaptation and only adapts the bypass coolant flows W0j. If compliance with the maximum change δmax cannot be achieved by adapting only the bypass coolant flows W0j, however, the useful coolant flows Wij must also be adapted.

So, based on the forecast, predictive predictive planning can take place. This can not only, as in FIG 7 shown, may be required with an increase in the requested total coolant flows WGj, but also with a reduction in 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 to follow the procedure from FIG 2 to be modified as follows in connection with FIG 8 is explained. An analogous modification is for the procedure 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 control states Ci of the valves 10 comply with minimum distances from a minimum control of the respective valve 10 and a maximum control of the respective valve 10. Furthermore, the control device 11 checks in step S21 to what extent the control state CP of the pump 7 has been changed. For example, the control device 11 can set an optimization problem with boundary conditions to be observed in the context of step S21. Such optimization problems are well known to those skilled in the art.

If the control device 11 comes to the result in step S21 that the control states Ci of the valves 10 adhere to the minimum distances and the control state CP of the pump 7 is kept constant as far as possible, the control device 11 goes to step S10. Otherwise, the control device 11 goes to a step S22. In step S22, the control device 11 varies the applied working pressure pA in the sense of the mentioned optimization.

The pump 7 has a permissible operating range. In particular, the operation of the pump 7 is as shown in FIG FIG 9 only permitted between a minimum speed nmin and a maximum speed nmax. Furthermore, the required amount of coolant - that is, 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 here as shown in FIG 9 depends on the difference between the pump pressure pP and the suction pressure pS. Without further measures, the pump 7 can therefore only be used within the in FIG 9 unshaded area. However, it is possible to use the pump 7 as shown in FIG FIG 10 to connect a short circuit valve 14 in parallel. This makes it possible - depending on the activation of the short-circuit valve 14 - to branch off between 0% and 100% of the coolant flow delivered by the pump 7 via the short-circuit valve 14 and 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 to use the entirety of pump 7 and bypass valve 14 not only within the in FIG 9 operate unshaded area. This would also be possible without the short-circuit valve 14. Rather, due to the short-circuit valve 14, it is additionally also possible, the entirety of the pump 7 and the short-circuit valve 14 within the in FIG 9 operate cross-hatched area. The determination of a control signal CK for the short-circuit valve 14 can, for example, in the context of step S9 (cf. FIG 2 and FIG 6 ) respectively. In this case, of course, 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 configuration according to FIG 10 first of all a check as to whether the pump 7 can be operated in a per se permissible range. If this is the case, the short-circuit valve 14 remains (completely) closed. If this is not the case, the short-circuit valve 14 is opened as far as is necessary to operate the pump 7 in a per se permissible range.

The present invention has been explained above for a simple configuration of the line system 9, namely as shown in FIG FIG 1 for a single direct connection from the pump 7 to the valves 10, the lengths of the individual stub lines between a junction 15 at which the stub lines to the individual valves 10 and the coolant outlets 4, 6 can be neglected. The present invention can, however, also be used when the line system 9 is designed to be more complex. In this case, it only needs to be taken into account that for each junction at which a branch occurs, the total of the coolant flows flowing into the respective junction and exiting from the respective junction must total 0 and that at the respective junction for each connected section of the line system 9 the same pressure must be given. The procedure is analogous to Kirchhoff's rules of electrical engineering. The procedure becomes computationally more complicated, but the system remains unchanged.

The system remains unchanged even if separate pumps are arranged in individual sections of the line system 9. This is discussed below in conjunction with FIG 11 explained in more detail using an example.

According to FIG 11 the line system 9 has three sections 16a, 16b, 16c. The section 16a extends from a pump 7a to a junction point 15. It has the length La and the cross section Aa. The two other sections 16b, 16c extend from node 15 to respective useful coolant outlets 4b, 4c and respective bypass coolant outlets 6b, 6c. A further pump 7b is located in section 16b shortly after node 15. 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. Valves 10b, 10c are arranged upstream of the coolant outlets 4b, 4c and 6b, 6c. In the FIG 11 The configuration shown can occur, for example, in a cooling section that has intensive cooling (coolant outlets 4b) and additionally laminar cooling (coolant outlets 4c) as well as a bypass coolant outlet 6b, 6c for each of the two coolings. The hot rolling stock 3 and the arrangement of the useful coolant outlets 4b, 4c in the cooling area 1 are shown in FIG FIG 11 not shown with order FIG 11 not to overload.

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

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

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 it follows, neglecting the height differences to be overcome for the pressure p15 at node 15: $$p\mathrm{15th}=\mathit{pAc}+p1c\left(\mathit{WC}\right)+p2c\left(\mathit{\delta Wc}\right)$$

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

The control states Cib of the valves 10b in section 16b according to FIG $$\mathit{Wib}=\mathit{give}\left(\mathit{Cib}\right)\cdot \sqrt{\mathit{pAb}/\mathit{<figure-callout\; id="0"\; label="pA"\; filenames="imgf0003.png,imgf0005.png"\; state="\{\{state\}\}">pA</figure-callout>}0}$$

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

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 it follows - again neglecting the height differences to be overcome - for the pump pressure pPb on 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 refer to section 16b. δWb is the change in the total coolant flow Wb $$\mathit{CPb}=\mathit{CPb}\left(\mathit{Wb},\mathit{pPb}-p\mathrm{15th}\right)$$

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

the control state CPa of the pump 7a can be determined.

The working pressures pAb and pAc are now target variables of the system, which are specified or, under certain circumstances, also from the Control device 11 can be determined. The total coolant flows Wb, Wc are known. To determine the changes δWb, δWc (and thus, as a result, also the change δWa), the above statements in connection with the FIG 2 and 6th to get expelled. The system of equations can thus be solved uniquely.

The present invention has many advantages. In particular, the required coolant flows Wi, WG are made available with a high degree of accuracy, without the need for a water tank or other compensation measures. The working pressure pA can be selected as required and even adapted during operation of the cooling section. The operating range of the cooling section is expanded. In particular, both the suction pressure pS and the pump pressure pP can be varied as required. This applies both to pure laminar cooling and to pure intensive cooling as well as to a cooling section which includes both laminar cooling and intensive cooling. Due to the adaptation of the working pressure pA and the pump pressure pP, a considerable amount of energy can be saved. In a hot strip mill, the average energy consumption that is required for pumping the coolant 2 can thereby be reduced by at least 30% compared to the solutions of the prior art, in some cases even by up to 50%. The associated cost savings can be in the range of well over € 100,000 per 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 being adversely affected.

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by the disclosed examples and other variants can be derived therefrom by the person skilled in the art without departing from the scope of the invention as defined by the claims.

List of reference symbols

1

Cooling area

2

Coolant

3

Rolling stock

4, 4b, 4c

Useful coolant outlets

5

Roll stand

5 '

reel

6, 6b, 6c

Bypass coolant outlet

6 '

Collecting container

7, 7a, 7b

pump

8th

Coolant reservoir

9

Line system

10, 10b, 10c

Valves

11

Control device

12

Computer program

13

Machine code

14th

Short circuit valve

15th

Junction

16a, 16b, 16c

Sections of the piping 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, 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

Functions

p2, p2a to p2c p15

pressure

pA, pAb, pAc

Working pressures

pA0

Nominal pressure

PH

Forecast horizon

pP, pPa, pPb

Pump pressures

pS

Suction pressure

S1 to S22

steps

T

Work cycle

WG, WG ', WGj

Total coolant flows

Wgmin, Wgmax

Coolant flows

Wi, W0, Wij W0 *

Target coolant flow

α, β

Weighting factors

δWG, δWa, δWb, δWc

Change in total coolant flow

δmax

Maximum change

ρ

Density of the coolant

Claims (16)

1. Operating method for a cooling zone for cooling hot rolling stock (3) of metal, wherein the cooling zone has a pump (7), which takes coolant (2) from a coolant reservoir (8) and feeds it via a system of lines (9) to a number of coolant outlets (4, 6), which are controlled by way of valves (10) arranged upstream of the coolant outlets (4, 6),

   - wherein, cyclically for a respective point in time, a control device (11) of the cooling zone

   -- taking into consideration coolant flows (Wi) that are intended to be delivered via the coolant outlets (4, 6) at the respective point in time, together with a working pressure (pA) of the coolant (2) present on the input side of the valves (10), determines activation states (Ci) for the valves (10),

   -- determines an overall coolant flow (WG) by adding together the coolant flows (Wi),

   -- taking into consideration the overall coolant flow (WG) and the working pressure (pA) of the coolant (2), determines a pump pressure (pP) that is intended to prevail on the output side of the pump (7), so that the working pressure (pA) is achieved on the input side of the valves (10),

   -- taking into consideration the overall coolant flow (WG), the pump pressure (pP) and a suction pressure (pS) prevailing on the input side of the pump (7), determines an activation state (CP) for the pump (7) and

   -- activates the valves (10) and the pump (7) in a way corresponding to the activation states (Ci, CP) determined, characterized

   in that, cyclically for the respective point in time, the control device (11) takes into consideration in the determination of the pump pressure (pP) in addition to the overall coolant flow (WG) and the working pressure (pA) of the coolant (2) also a change (δWG) of the overall coolant flow (WG) .
2. Operating method according to Claim 1,
   characterized
   in that the control device (11) takes into consideration in the determination of the pump pressure (pP) a line resistance (p2) of the system of lines (9) that is to be overcome by the overall coolant flow (WG).
3. Operating method according to Claim 1 or 2,
   characterized
   in that, in addition to the coolant flows (Wij) that are to be delivered via the coolant outlets (4, 6) at the respective point in time, coolant flows (Wij) that are forecast for a forecast horizon (pH) and are intended to be delivered via the coolant outlets (4, 6) for a number of future points in time are known to the control device (11), and in that the control device (11) takes into consideration the forecast coolant flows (Wij) of at least one of the future points in time in the determination of the activation state (CP) of the pump (7).
4. Operating method according to Claim 3,
   characterized
   in that the control device (11) determines for at least one future point in time the associated overall coolant flow (WGj) and takes it into consideration in the determination of the change (δWG) of the overall coolant flow (WG0).
5. Operating method according to Claim 4, characterized in that, in addition to the forecast coolant flows (Wij) of the at least one future point in time, the control device (11) also takes into consideration furthermore the overall coolant flow (WG') of at least one past point in time in the determination of the change (δWG) of the overall coolant flow (WGO) and in that the respective point in time lies midway between the at least one future point in time and the at least one past point in time.
6. Operating method according to Claim 4 or 5,
   characterized

   - in that the coolant outlets (4, 6) comprise effective coolant outlets (4) and bypass coolant outlets (6),

   - in that the hot rolling stock (3) is cooled exclusively by means of the coolant flows (Wij) delivered via the effective coolant outlets (4),

   - in that, on the basis of the coolant flows (Wij) to be delivered via the effective coolant outlets (4) for the respective point in time and/or the future points in time, the control device (11) determines the coolant flows (Wi0) to be delivered via the bypass coolant outlets (6) for the respective point in time and/or the future points in time in such a way that each overall coolant flow (WGj) that was taken into consideration at an earlier point in time before the respective point in time in the course of the determination of the change (δWG) of the overall coolant flow (WG) applicable for the earlier point in time is maintained.
7. Operating method according to one of Claims 3 to 6, characterized
   in that, in the determination of the activation state (CP) of the pump (7), the control device (11)

   - determines for the future points in time on the basis of the respective forecast coolant flows (Wij) a respective forecast overall coolant flow (WGj),

   - determines for the future points in time changes of the determined overall coolant flows (WGj) and

   - depending on whether a predetermined maximum change (δWG) is maintained or exceeded, adapts the respective overall coolant flows (WGj) for the future point in time and/or future points in time within the forecast horizon (PH), so that as far as possible both the change of the overall coolant flow (WGO) for the respective point in time and the changes of the determined overall coolant flows (WGj) for the future points in time maintain the maximum change (δWG).
8. Operating method according to Claim 1 or 2 characterized

   - in that the coolant outlets (4, 6) comprise effective coolant outlets (4) and bypass coolant outlets (6),

   - in that the hot rolling stock (3) is cooled exclusively by means of the coolant flows (Wi) delivered via the effective coolant outlets (4) and

   - in that the control device (11) determines the coolant flows (W0) to be delivered via the bypass coolant outlets (6) in such a way that the coolant flows (W0) to be delivered via the bypass coolant outlets (6) are as close as possible to a bypass target coolant flow (W0*) and a change (δWG) of the overall coolant flow (WG) to be delivered altogether via the effective coolant outlets (4) and the bypass coolant outlets (6) is as small as possible.
9. Operating method according to one of the above claims,
   characterized
   in that the valves (10) can be activated steplessly or at least in multiple steps.
10. Operating method according to one of the above claims,
    characterized
    in that the control device (11) determines the operating pressure (pA) in such a way that the activation states (Ci) of the valves (10) maintain minimum margins from a minimum activation and a maximum activation and the activation state (CP) of the pump (7) is kept constant as far as possible.
11. Operating method according to one of the above claims,
    characterized
    in that the control device (11) additionally also takes into consideration in the course of the determination of the pump pressure (pP) a height difference (H) to be overcome.
12. Operating method according to one of the above claims, characterized in that the control device (11) additionally determines a control signal (CK) for a short-circuit valve (14) connected in parallel with the pump (7) and activates the short-circuit valve (14) in a way corresponding to the control signal (CK) determined.
13. Computer program, which comprises machine code (13) that can be processed by a control device (11) for a cooling zone, wherein the processing of the machine code (13) by the control device (11) brings about the effect that the control device (11) operates the cooling zone in accordance with an operating method according to one of the above claims.
14. Control device for a cooling zone, wherein the control device is programmed with a computer program (12) according to Claim 13, so that the control device operates the cooling zone in accordance with an operating method according to one of Claims 1 to 12.
15. Cooling zone for cooling hot rolling stock (3) of metal,

    - wherein the cooling zone has a pump (7), which takes coolant (2) from a coolant reservoir (8) and feeds it via a system of lines (9) to a number of coolant outlets (4, 6), which are controlled by way of valves (10) arranged upstream of the coolant outlets (4, 6),

    - wherein the cooling zone has a control device (11), which operates the cooling zone in accordance with an operating method according to one of Claims 1 to 12.
16. Cooling zone according to Claim 15,
    characterized
    in that a cooling region (1) of the cooling zone within which the coolant (2) is applied to the hot rolling stock (3) is arranged within a rolling train and/or is arranged upstream of a rolling train and/or is arranged downstream of the rolling train.

Images