EP3826780B1 - Cooling section with adjustment of the cooling agent flow by means of pumps - Google Patents

Description

field of technology

• wobei einer Anzahl von Aufbringeinrichtungen der Kühlstrecke über eine jeweilige Versorgungsleitung und eine jeweilige Pumpe ein jeweiliger Ist-Strom eines flüssigen, auf Wasser basierenden Kühlmittels zugeführt wird,
• wobei der jeweilige Ist-Strom des Kühlmittels mittels der jeweiligen Aufbringeinrichtung auf das heiße Walzgut aufgebracht wird,
• wobei das heiße Walzgut innerhalb der Kühlstrecke während des Aufbringens des Kühlmittels in einer horizontalen Transportrichtung transportiert wird.

The present invention is based on an operating method for a cooling section, which is arranged within a rolling train or is arranged upstream or downstream of the rolling train and by means of which a hot metal rolling stock is cooled,

• a respective actual flow of a liquid, water-based coolant being supplied to a number of application devices of the cooling section via a respective supply line and a respective pump,
• the respective actual flow of the coolant being applied to the hot rolling stock by means of the respective application device,
• wherein the hot rolling stock is transported in a horizontal transport direction within the cooling section during the application of the coolant.

• wobei die Kühlstrecke eine Anzahl von Aufbringeinrichtungen aufweist, denen über eine jeweilige Versorgungsleitung der Kühlstrecke und eine jeweilige Pumpe der Kühlstrecke ein jeweiliger Ist-Strom eines flüssigen, auf Wasser basierenden Kühlmittels zugeführt wird,
• wobei der jeweilige Ist-Strom des Kühlmittels mittels der jeweiligen Aufbringeinrichtung auf das heiße Walzgut aufgebracht wird,
• wobei das heiße Walzgut in der Kühlstrecke während des Aufbringens des Kühlmittels in einer horizontalen Transportrichtung transportiert wird.

The present invention is also based on a cooling section which is arranged within a rolling train or is arranged upstream or downstream of the rolling train and by means of which a hot metal rolling stock is cooled,

• wherein the cooling section has a number of application devices to which a respective actual flow of a liquid, water-based coolant is supplied via a respective supply line of the cooling section and a respective pump of the cooling section,
• the respective actual flow of the coolant being applied to the hot rolling stock by means of the respective application device,
• wherein the hot rolling stock is transported in a horizontal transport direction in the cooling section during the application of the coolant.

In the cooling section of a rolling mill, a metallic rolling stock is cooled after rolling. The rolling stock can consist of steel or aluminum, for example. It can be a flat rolled product (strip or heavy plate), a bar-shaped rolled product or a profile, as required. Precise temperature control in the cooling section is customary in order to set the desired material properties and keep them constant with less scatter. For this purpose, several spray bars are installed along the cooling section, in particular in a cooling section downstream of the rolling train, by means of which a liquid coolant, usually water, is applied to the rolling stock from above and below to cool the hot rolling stock. The amount of water flowing through the respective spray bar should be adjustable as quickly and precisely as possible.

State of the art

In order to adjust the amounts of water supplied to the spray boom, it is known, for example, to arrange switching valves or control valves in the supply lines. Switching valves can only be controlled purely binary. So they are either fully open or fully closed. Control valves can be continuously adjusted so that the amount of water fed to the respective spray bar can also be continuously adjusted.

In the case of control valves, the valves can be designed as control flaps or as ball valves. Control flaps are relatively simple and inexpensive. However, they can only be operated with relatively small pressure differences of mostly a maximum of 1 bar. Otherwise cavitations will occur, which will damage the control flap very quickly. Control flaps are therefore not particularly suitable for intensive cooling. But they are also often a disadvantage in a laminar cooling section. In particular, they often show a switching hysteresis. The switching hysteresis causes that with the same control the set flap angle varies in size, depending on whether the control flap is moved from a more open position or from a more closed position to the new position to be assumed. Ball valves do not have a flapper, but rather a pierced ball that is rotated in a tube. Depending on the rotational position of the ball, the coolant is provided with a larger or smaller cross-section for the flow. Ball valves can be operated with higher pressure differences of up to approx. 3 bar. A hysteresis does not occur with them or is negligibly small. However, ball valves are expensive.

In another solution, the coolant is permanently supplied to the spray boom. However, there is a controllable deflection plate. Depending on the position of the deflection plate, the coolant is either supplied to the rolling stock or flows off to the side without contributing to the cooling of the rolling stock. With this arrangement, fast switching operations are possible without pressure surges. However, a continuous adjustment of the amount of water is not possible. Furthermore, the full flow of coolant must be pumped permanently.

All types of valves and the deflection plates require appropriate actuators. Pneumatically driven servomotors are common. Position control is also required for control valves. This continuously compares the actual position of the respective control valve with its target position and readjusts the actual position until there is sufficient agreement with the target position.

All arrangements also have in common that an external supply of coolant must be available. The coolant can, for example, be taken from an elevated tank or transported via a larger pipeline from a pump station that is further away. Combinations of these procedures are also possible. For example, in so-called intensive cooling, the water is often first taken from a high tank. Then the pressure via booster pumps increased to a variable extent and thus made available with correspondingly variable pressure for intensive cooling. There are usually several booster pumps, but they are all connected in parallel, ie they all draw the cooling liquid from the same reservoir on the input side and feed it to a common collection point on the output side. The intensive cooling is equipped with several spray bars, which - starting from the booster pumps or the common collection point - the coolant is supplied individually via a respective supply line. Ball valves are arranged in the supply lines, which are actuated to adjust the quantity of coolant supplied to the respective spray bar.

• Bei Schaltventilen gibt es Druckschläge beim Abschalten. Daher können Schaltventile nicht beliebig schnell abgeschaltet werden. Übliche Schaltzeiten liegen oberhalb von 1 Sekunde, manchmal bei bis zu 2 Sekunden.
• Mit Regelklappen und Kugelventilen werden ähnliche Regelzeiten erreicht. Weiterhin ist für jedes Regelventil eine Positionsregelung erforderlich. Die erreichbare Genauigkeit liegt bei ca. 1 % bis 2 %.
• Auch bei Regelventilen gibt es Druckschläge beim Abschalten. Daher können auch Regelventile nicht beliebig schnell geschlossen werden. Übliche Schaltzeiten liegen im Bereich von ca. 1 Sekunde.
• Bei allen Ventilen treten Strömungsverluste auf, die zu einem erhöhten Verschleiß und auch zu einem erhöhten Energieverbrauch führen.
• Die pneumatischen Stellantriebe sind anfällig für Defekte. Sie leiden insbesondere bei häufigen Stellvorgängen. Weiterhin benötigen sie zusätzliche Energie für die Steuerluft, die darüber hinaus gereinigt und getrocknet werden muss und beispielsweise von einem eigenen Kompressor zur Verfügung gestellt werden muss.

There are various disadvantages in the prior art.

• With switching valves, there are pressure shocks when they are switched off. Therefore switching valves can not be switched off arbitrarily quickly. Usual switching times are above 1 second, sometimes up to 2 seconds.
• Similar control times are achieved with control flaps and ball valves. Furthermore, a position control is required for each control valve. The achievable accuracy is around 1% to 2%.
• Pressure shocks also occur when switching off control valves. For this reason, control valves cannot be closed as quickly as desired. Usual switching times are in the range of approx. 1 second.
• Flow losses occur with all valves, which lead to increased wear and also to increased energy consumption.
• The pneumatic actuators are prone to failure. They suffer in particular with frequent positioning processes. Furthermore, they require additional energy for the control air, which also has to be cleaned and dried and, for example, has to be provided by its own compressor.

From the WO 2010/040614 A2 a descaling device is known in which a pump is driven via a variable-speed drive. When the drive is actuated, an operating state of the descaling area and a degree of filling of a high-pressure accumulator are taken into account.

From the US 2008/0035298 A1 a casting process is known which uses, among other things, a cooling water source comprising a water-cooled coil. The cooling water is fed to the coil by a pump that can be turned on and off and has a mechanism to control the amount of coolant. The liquid is recirculated. The temperature of the cast metal strand is recorded and sent to a control device. Depending on this, the control device controls the cooling water source.

From the US 2010/0 218 516 A1 a method is known in which a metal strip is cooled in a cooling device with a liquid cooling medium as part of a heat treatment of the metal strip. The metal band runs vertically from bottom to top. The cooling medium is pentane or a mixture of pentane and hexane. The metal strip is in an atmosphere of protective gas while the cooling medium is being applied. Depending on the temperature of the metal strip on the inlet side and outlet side of the cooling device and the speed of the metal strip, a quantity of coolant is determined which is to be conducted by a pump to the application devices of the cooling device. The pump is controlled according to the result.

From the US 2007/0 074 846 A1 a casting process is known in which the cast strand is passed through a cooling chamber in which the cast strand is cooled with a liquid cooling medium. The liquid cooling medium is a metal or a molten salt. The liquid cooling medium is taken from a reservoir by means of a circulating pump, fed to the cooling chamber and then from the cooling chamber again reservoir supplied. The amount of liquid is regulated as a function of the temperatures at which the liquid cooling medium is supplied to or removed from the cooling chamber, and as a function of the pressure on the inlet side of the cooling chamber.

From the US 2009/0 314 460 A1 a casting process is known in which the cast strand is formed by means of a twin-roller casting machine. The rollers are internally cooled with a liquid coolant. The liquid cooling medium is a metal or a molten salt. The liquid cooling medium is taken from a reservoir by means of a circulating pump, fed to the rollers and then fed back to the reservoir from the cooling chamber.

From the US 2012/0 298 224 A1 the forward-looking operation of a pump is known in the context of a rolling mill with a downstream cooling section. However, this pump does not feed application devices directly, by means of which the cooling medium is applied to the hot rolling stock, but only conveys the cooling medium into a reservoir, so that this is always sufficiently filled. The application of the coolant to the rolling stock itself is not explained in detail.

From the EP 2 898 963 A1 a cooling section is known, which is arranged downstream of a rolling train and by means of which a hot metal rolling stock is cooled. In this cooling section, there are a number of application devices to which a respective actual flow of a liquid, water-based coolant is supplied via a respective supply line. The respective actual flow of the coolant is applied to the hot rolling stock by means of the respective application device. The hot rolling stock is transported in a horizontal transport direction within the cooling section during the application of the coolant.

From the EP 2 767 353 A1 is also known a cooling line, which is downstream of a rolling mill and by means of which a hot rolled metal is cooled. In this cooling section, there are a number of application devices to which a respective actual flow of a liquid, water-based coolant is supplied via a respective supply line. The respective actual flow of the coolant is applied to the hot rolling stock by means of the respective application device. The hot rolling stock is transported in a horizontal transport direction within the cooling section during the application of the coolant. Valves are arranged in the supply lines, the opening positions of which are dynamically adjusted by a control device of the cooling section. A common pump arranged upstream of the supply lines is set by the control device in accordance with a total flow to be applied in its entirety to the rolling stock by means of the application device.

Summary of the Invention

The object of the present invention is to create possibilities by means of which a cooling section with superior operating properties can be realized in a simple and reliable manner.

The object is achieved by an operating method with the features of claim 1. Advantageous configurations of the operating method are the subject matter of dependent claims 2 to 9.

According to the invention, an operating method of the type mentioned at the beginning is configured in that a control device of the cooling section dynamically determines a respective target control state for the respective pump and the respective pump as a function of a respective target flow of the coolant to be applied to the hot rolling stock by means of the respective application device controls accordingly, so that the funded by the respective pump respective actual current the respective target current is approached as closely as possible at all times.

The respective pump - more precisely: the drive for the respective pump - is therefore a variable-speed drive. For example, it can be controlled by an inverter. As part of the dynamic control, only the respective pump is controlled, but not any valve arranged in the respective supply line.

Control or regulation can take place as required. In the case of regulation, the respective actual flow of the liquid coolant is recorded on the input side or output side of the respective pump and fed to the control device.

In many cases, the rolled stock is flat rolled stock, such as strip or plate. In this case, it is possible for the liquid coolant to be applied to the rolling stock from both sides by means of the respective application device. Alternatively, it is possible for the liquid coolant to be applied to the rolling stock by means of the respective application device from only one side, in particular from above or below. Of course, it is also possible in this case to apply the coolant to the other side of the flat rolling stock, so that the flat rolling stock is cooled simultaneously from above and from below, for example. In this case, however, two application devices are required, which are controlled separately and, in principle, are also operated independently of one another. In this case, the operating method according to the invention is carried out twice, so to speak. However, both pumps can be controlled uniformly by one and the same control device. In this case, the control device can, to the extent necessary, also take into account mutual dependencies in the cooling.

It is possible for the respective application device to have a plurality of spray nozzles which are arranged one behind the other as seen in the transport direction of the rolling stock. For example, groups of spray nozzles can be formed within a single spray bar, which are uniformly supplied with coolant via the respective supply line and the respective supply line and the respective pump. Groups of spray nozzles can also be formed, which overlap several spray bars and are uniformly supplied with coolant via the respective supply line and the respective pump. This configuration can be particularly advantageous in that fewer pumps are required than if each spray bar were supplied with coolant via its own supply line and its own pump.

In many cases, the respective application device has a plurality of spray nozzles, which are arranged next to one another, viewed transversely to the transport direction of the rolling stock. This can be particularly useful for flat rolling stock (strip or heavy plate). In this case, the respective application device can extend over the full width of the rolling stock or only over part of the width. In the latter case, several application devices are arranged next to one another, which are each supplied with coolant via their own supply line and their own pump, with the pumps being controlled independently of one another.

It is possible that no shut-off device is arranged between the respective pump and the respective application device. Alternatively, it is possible for a shut-off device to be arranged between the respective pump and the respective application device. In this case, however, the shut-off device is either kept fully open while the rolling stock is being transported through the cooling section or is only actuated to open and close when the speed of the respective pump is below a minimum speed. The respective minimum speed is so small in this case that only a very small actual flow is conveyed. It is also possible that the shut-off device can only be actuated manually in order to be able to take the respective application device out of operation, for example for maintenance purposes.

It is also possible for a respective return line to be arranged in parallel with the respective pump. In this case, the return line has a smaller cross-section than the respective supply line. As a result, pumps can be used where, due to their design, a certain minimum flow of coolant must always be maintained. However, the minimum flow is considerably smaller than the respective maximum possible flow of coolant. If, in such a case, an amount of coolant that is smaller than the respective minimum current is to be applied to the rolling stock, it is only necessary to open a valve arranged in the return line accordingly (bypass operation).

It is also possible for the respective pump to be operated as a generator or with inverted direction of rotation whenever the respective setpoint current falls below a respective lower limit value. As a result, very small actual currents can also be realized. Furthermore, it can be prevented in this way that an actual current that is too high flows through a pump that is not self-locking when the target current is small.

In a preferred embodiment, it is provided that a non-return valve or a non-return flap is arranged in the respective supply line between the respective pump and the respective application device. This can prevent the respective pump from running dry and being damaged as a result.

Provision is preferably made for an inlet-side pressure of the liquid coolant to be recorded upstream of the respective pump and for the control device to record the inlet-side pressure recorded Pressure taken into account when determining the respective target control state of the respective pump. As a result, the respective setpoint control state for the respective pump can be determined more precisely.

It is possible for an outlet-side pressure of the liquid coolant to be detected downstream of the respective pump and for the control device to take into account the detected outlet-side pressure when determining the respective setpoint control state of the respective pump. This leads to an even more precise determination of the respective setpoint control state.

The control device preferably determines the respective setpoint current as a function of a respective thermodynamic energy state of the rolling stock that exists immediately before the respective application device is reached. As a result, a particularly precise temperature control can be implemented. The thermodynamic energy state of the rolling stock can be known to the control device, for example on the basis of a previous measurement. Alternatively, it is possible that, starting from a known thermodynamic energy state, a model-based calculation of the respective thermodynamic energy state takes place.

In a cooling section, many application devices are often arranged sequentially one behind the other. The associated actual flows of the coolant are thereby sequentially applied to the hot rolling stock by means of the application devices. In this case, the operating method according to the invention is preferably configured in that the control device determines the respective thermodynamic energy state of the rolling stock based on the thermodynamic energy state of the rolling stock before the immediately preceding application device, also taking into account the setpoint flow of the coolant or the actual flow of the coolant is to be or is applied to the hot rolling stock by means of the immediately preceding application device. The calculation of the thermodynamic Energy states can therefore occur sequentially one after the other.

The object is also achieved by a cooling section with the features of claim 10. Advantageous configurations of the cooling section are the subject matter of dependent claims 11 to 18.

According to the invention, a cooling section of the type mentioned at the outset is designed in that the control device is designed in such a way that it dynamically determines a respective setpoint control state for the respective pump as a function of a respective setpoint flow of the coolant to be applied to the hot rolling stock by means of the respective application device and controls the respective pump accordingly, so that the respective actual current delivered by the respective pump is approximated as closely as possible to the respective target current at all times.

The advantageous configurations of the cooling section essentially correspond to those of the operating method. The advantages achieved in this way also correspond to the respective corresponding configurations of the operating method.

Brief description of the drawings

FIG 1

eine einer Walzstraße nachgeordnete Kühlstrecke,

FIG 2

eine einer Walzstraße vorgeordnete Kühlstrecke,

FIG 3

eine innerhalb einer Walzstraße angeordnete Kühlstrecke,

FIG 4

eine einzelne Aufbringeinrichtung,

FIG 5

ein Zeitdiagramm,

FIG 6

ein Diagramm,

FIG 7

einen Abschnitt einer Versorgungsleitung mit einer Pumpe,

FIG 8

ein Diagramm,

FIG 9

einen Abschnitt einer Versorgungsleitung mit einer Pumpe,

FIG 10

die Funktionsweise einer Steuereinrichtung,

FIG 11

Spritzbalken und Spritzdüsen und

FIG 12

Spritzbalken und Spritzdüsen.

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

FIG 1

a cooling section downstream of a rolling train,

FIG 2

a cooling section upstream of a rolling train,

3

a cooling section arranged within a rolling train,

FIG 4

a single applicator,

5

a time chart,

6

a chart,

FIG 7

a section of a supply line with a pump,

8

a chart,

9

a section of a supply line with a pump,

10

the functioning of a control device,

11

Spray bars and spray nozzles and

12

Spray bars and spray nozzles.

Description of the embodiments

According to FIG 1 a hot rolling stock 1 made of metal is to be cooled in a cooling section 2. The cooling line 2 is according to FIG 1 downstream of a rolling mill. is shown in FIG 1 only one rolling stand 3 of the rolling train, namely the last rolling stand 3 of the rolling train. As a rule, however, the rolling train has a plurality of roll stands 3 through which the hot rolling stock 1 passes sequentially one after the other. In the case of the design according to FIG 1 the hot rolling stock 1 enters the cooling section 2 immediately after passing through the last rolling stand 3 of the rolling train. A time interval between rolling in the last rolling stand 3 of the rolling train and entry into the cooling section 2 is in the range of a few seconds.

Alternatively, the cooling section 2 could be as shown in FIG 2 be upstream of the rolling mill. is shown in FIG 2 also only a single rolling stand 4 of the rolling train, namely the first rolling stand 4 of the rolling train. However, the rolling mill often has - just as in the case of the design according to FIG 1 - Several roll stands 3, which are traversed by the hot rolling stock 1 sequentially one after the other. In the case of the design according to FIG 2 the hot rolling stock 1 is rolled in the first roll stand 4 of the rolling mill immediately after leaving the cooling section 2. A temporal one The distance between the cooling in the cooling section 2 and the rolling in the first roll stand 4 of the rolling train is in the range of a few minutes. But it can also be just a few seconds.

Alternatively, the cooling section 2 could be as shown in 3 be arranged within the rolling train. are shown in 3 two roll stands 5 of the rolling mill. In this case, the cooling of the rolling stock 1 - more precisely: a section of the rolling stock 1 - takes place in the cooling section 2 between the rolling in the two roll stands 5 of the rolling train. A time interval between the cooling in the cooling section 2 and the rolling in the two successive roll stands 5 of the rolling train is in the range of a few seconds. According to the illustration in 3 the cooling section 2 is arranged between two successive rolling stands 5 of the rolling train. However, it could also extend over a larger area, so that the cooling section 2 extends through at least one in 3 not shown further roll stand is divided into a corresponding number of sections.

The rolling stock 1 consists of metal. For example, the rolling stock 1 can be made of steel or aluminum. Other metals are also possible. In the case of steel, the temperature of the rolling stock 1 upstream of the cooling section 2 is generally between 750° C. and 1,200° C. Cooling to a lower temperature takes place in the cooling section 2 . It is possible in individual cases that the lower temperature is only slightly below the temperature in front of the cooling section 2 . Particularly in the case where the cooling section 2 is arranged downstream of the rolling train, the rolling stock 1 is generally cooled to a significantly lower temperature, for example to a temperature between 200° C. and 700° C.

The hot rolling stock 1 is fed to the cooling section 2 in a horizontal transport direction x. The hot rolling stock 1 does not change its transport direction x within the cooling section 2 . So it is also within the cooling section 2 horizontal transported. After leaving the cooling section 2, the rolling stock 1 can either maintain or change its transport direction. If the hot rolling stock 1 is a strip, it can be deflected downwards at an angle, for example, in order to feed it to a coiler. If the hot rolling stock 1 is a heavy plate, it mostly keeps the transport direction x. A roller table which may be required for transporting the hot rolling stock 1 is not shown in the figures.

The cooling section 2 has a number of application devices 6 . A coolant 7 is applied to the rolling stock 1 by means of the application devices 6 . The coolant 7 is water. If necessary, additives can be added to the water to a small extent (maximum 1% to 2%). In any case, however, the coolant 7 is a liquid, water-based coolant.

At a minimum, a single applicator 6 is present. In many cases, however, several application devices 6 are present. For example, the application devices can be used as shown in FIG 1 be arranged one behind the other. In this case, the application devices 6 sequentially apply their respective portion of the coolant 7 to the rolling stock 1 one after the other. In this context, the term “sequentially one after the other” refers to a specific section of the rolling stock 1, since this sequentially runs through areas in which the individual application devices 6 apply their respective proportion of the coolant 7 to the corresponding section of the rolling stock 1. The number of application devices 6 is often in the two-digit range, sometimes even in the upper two-digit range. A sequential arrangement one behind the other is generally implemented in particular when the cooling section 2 is arranged downstream of the rolling train. However, it can also be given in other cases.

The application devices 6 are connected to a reservoir 9 of the coolant 7 via a respective supply line 8 . In the present case, the reservoir 9 is the same for all application devices 6. However, several independent reservoirs 9 could also be present. A respective pump 10 is arranged in each supply line 8 . In principle, the pumps 10 can be arranged at any desired points within the supply lines 8 . In practice, however, it is advantageous if the pumps 10 are arranged as close as possible to the reservoir 9.

Below is - representative of all applicators 6 - in conjunction with FIG 4 the operation of one of the application devices 6 is explained in more detail. The other application devices 6 are operated in principle in the same way. For each application device 6, however, the respective mode of operation can be determined individually. It is therefore possible, but not necessary, to operate the application devices 6 in the same way.

An actual flow F of the coolant 7 is supplied to the application device 6 via the supply line 8 and the pump 10 from the reservoir 9 . The actual current F is applied to the hot rolling stock 1 by means of the respective application device 6 . A distance of the application device 6 - for example from spray nozzles - from the rolling stock 1 is usually between 20 cm and 200 cm.

A control device 11 of the cooling line 2 is aware of a corresponding setpoint current F*, which is to be applied to the hot rolling stock 1 by means of the application device 6 . As a rule, the target current F* is not constant over time, but variable, ie a function of the time t. Depending on the setpoint flow F* of the coolant 7, the control device 11 dynamically determines a setpoint control state S* for the pump 10. It controls the pump 10 accordingly. The pump 10 thus applies an outlet-side pressure pA to the coolant 7 on the outlet side of the pump 10 . The pressure pA on the outlet side varies according to the setpoint activation state S*. But it is in every operating state below 10 bar. Usually it is even at a maximum of 6 bar. In any operating state, however, the actual flow F delivered by the pump 10 is always brought as close as possible to the target flow F*.

The setpoint activation state S* can also be determined without further ado. This will be explained below using a simple example.

Assume that the pump 10 is located in close proximity to the reservoir 9 . The supply line 8 has a length 1 and a cross section A. The pressure on the inlet side of the pump 10 is referred to below as pE. The pressure in the application device 6 is denoted by p0.

Then the relationship applies first $$f=\mathit{FN}\cdot \sqrt{\frac{\mathrm{<figure-callout\; id="0"\; label="p"\; filenames="imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}0}{\mathit{pn}}}$$

FN is a nominal current flowing out of the applicator 6 when the coolant 7 in the applicator has a nominal pressure pN. The nominal current FN and the nominal pressure pN are fixed and determined by the design of the application device 6 . They can be determined, for example, by a one-off measurement of the flow that results at a pressure—which, in principle, can be set arbitrarily.

mit ρ = Dichte des Kühlmittels 7 und r = Widerstandsbeiwert für den Strömungswiderstand des Kühlmittels 7 in der Versorgungsleitung 8.The relationship also applies to the actual current F $$\dot{f}=\frac{A}{\rho \cdot l}\left(\mathit{pA}-\mathrm{<figure-callout\; id="0"\; label="p"\; filenames="imgf0003.png"\; state="\{\{state\}\}">p</figure-callout>}0-l\cdot \mathrm{right}\cdot {\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}^2\right)$$

with ρ = density of the coolant 7 and r = resistance coefficient for the flow resistance of the coolant 7 in the supply line 8.

If you now solve equation (1) for the pressure p0 and insert it into equation (2), the following equation (3) results: $$\dot{f}=\frac{A}{\rho \cdot l}\cdot \left(\mathit{pA}-\frac{\mathit{pn}}{{\mathit{<figure-callout\; id="2"\; label="FN"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FN</figure-callout>}}^2}\cdot {\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}^2-l\cdot \mathrm{right}\cdot {\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}^2\right)$$

Equation (3) is now solved for pA: $$\mathit{pA}=\left(\frac{\mathit{pn}}{{\mathit{<figure-callout\; id="2"\; label="FN"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">FN</figure-callout>}}^2}+l\cdot \mathrm{right}\right)\cdot {\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">f</figure-callout>}}^2+\frac{\mathit{\rho l}}{A}\cdot \dot{f}$$

The actual current F is given without further ado. For example, it can be measured. The desired derivative of the actual current F over time results directly from the difference between the target current F* and the actual current F. If necessary, the derivative of the actual current F over time can be limited in order to keep the pressure pA on the outlet side within permissible limits keep.

The required outlet-side pressure pA can thus be determined without further ado. With the desired pressure pA on the outlet side and the pressure pE on the inlet side, however, the associated speed n can be determined according to the characteristic curve f of the pump 10, which is usually readily known: $$n=ƒ\left(\mathit{pA}-\mathit{PE},f\right)$$

ermittelt werden, wobei F0 eine geeignet gewählte Konstante ist.Furthermore, if the actual current F is not measured, it can easily be determined using the relationship $$f=\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="imgf0003.png"\; state="\{\{state\}\}">f</figure-callout>}0+{\displaystyle \underset{O}{\overset{t}{\int }}\dot{f}\left(\tau \right)}\mathit{d\tau }$$

can be determined, where F0 is a suitably chosen constant.

Furthermore, the actual current F is available to the control device 11 at any time—either by measuring it or by calculating it according to equation (6). This is necessary in order to be able to update a thermodynamic energy state H of the rolling stock 1 by calculation. This will be discussed in more detail later. The only remaining dead time of the application device 6 is the generally very short time that the coolant 7 needs to strike the rolling stock 1—calculated from the point at which it emerges from the application device 6 .

Control or regulation can take place as required. In the case of regulation, the actual current F is recorded on the input side or on the output side of the pump 10 and fed to the control device 11 . If no such detection takes place, the actual current F is controlled.

In order to be able to control the pump 10 accordingly, the pump 10—more precisely: its drive 12—must be able to be operated at variable speeds. For example, the drive 12 of the pump 10 can be converter-controlled for this purpose. Such controls are generally known to those skilled in the art and therefore do not need to be explained in more detail. The pump 10 can preferably be operated in a control range between 0 and a maximum speed. A seal of the pump 10 should also be designed for low speeds. However, this is easily possible. Corresponding pumps 10 are known to those skilled in the art.

In order to adapt the actual current F to the target current F*, the pump 10 is accordingly dynamically actuated and the actual current F is thereby brought as close as possible to the target current F*. On the other hand--in contrast to the prior art--no valve arranged in the supply line 8 is actuated. Such a valve - should it be present - rather remains permanently fully open.

Within the scope of the operating method according to the invention, it is therefore possible for no shut-off device to be arranged between the pump 10 and the application device 6 . Alternatively, it is as shown in FIG 4 It is possible for such a shut-off device 13 to be arranged between the pump 10 and the application device 6 . The shut-off device 13 is in FIG 4 only drawn in dashed because it can exist, but does not have to exist. If the shut-off device 13 is present, the shut-off device 13 can be operated in two different ways.

On the one hand, it is possible for the shut-off device 13 to be kept permanently fully open while the rolling stock 1 is being transported through the cooling section 2 . this is in 5 illustrated by the fact that the rolling stock 1 enters the cooling section 2 at a point in time t1. However, before the time t1, the shut-off device 13 is opened at a time t2. In an analogous manner, the rolling stock 1 runs out of the cooling section 2 at a point in time t3. Only after the point in time t3 is the shut-off device 13 closed again at a point in time t4. Between times t2 and t4, the shut-off device 13 remains fully open at all times.

On the other hand, it is possible for the shut-off device 13 to be actuated only when the speed of the pump 10 is below a minimum speed nmin. This is discussed below in connection with 6 explained in more detail. According to 6 the speed of the pump 10 can vary between 0 and a nominal speed nmax. If and as long as the speed n remains below a minimum speed nmin, the shut-off device 13 can be actuated. This applies both to an opening and to a closing of the shut-off device 13. However, if and as soon as the speed n reaches or exceeds the minimum speed nmin, the shut-off device 13 remains open. In this case, in particular, the shut-off device 13 must first be opened at a very low speed n. Thereafter, the operation of the applicator takes place 6, during which only the pump 10 is controlled accordingly to set the actual current F. Only when the speed n falls below the minimum speed nmin again can and may the shut-off device 13 be actuated again.

Depending on the type of pump 10, the pump 10 must always deliver a minimum flow when it is operated. The minimum current can be greater than the target current F*. In order to be able to cover this case as well, it is as shown in FIG 7 possible to arrange the pump 10 a return line 14 in parallel. However, the return line 14 has a smaller cross section than the supply line 8 . In particular, the return line 14 only has to be designed to be able to convey the minimum current. The supply line 8, on the other hand, must be designed to be able to convey a maximum current, with the maximum current being greater—usually considerably greater—than the minimum current. By design according to FIG 7 it is possible to use a pump as the pump 10 in which, due to the design, a certain minimum flow of coolant 7 must always be maintained. However, the minimum flow is considerably smaller than the maximum possible flow of coolant 7. If in the case of the design according to FIG 7 if an amount of coolant 7 is to be applied to the rolling stock 1 which is less than the minimum current, it is only necessary to open a valve 15 arranged in the return line 14 accordingly (bypass operation). In this case, the shut-off device 13 must also be present. In this case, the shut-off device 13 and the valve 15 must be in the form of control valves. In this case too, however, the shut-off device 13 is only closed (completely or partially) when the actual current F is below the minimum current. The situation in which the target current F* assumes values below the minimum current only occurs very rarely in practice. As a rule - that is, if the actual current F is above the minimum current - the shut-off device 13 can therefore completely open and the bypass valve 15 remain fully closed.

According to 8 the target current F* can vary. In the case of larger values, a speed n of the pump 10 is at values worth mentioning, so that the pump 10 actively conveys (pumps) the coolant 7 . As a result, the pump 10 consumes energy E. However, if the setpoint current F* decreases, it can happen that the pump 10 continues to rotate in the same direction of rotation as with larger values, but the pump 10 is operated as a generator. So it releases energy E. For example, the energy E can be fed back into a supply network via the drive 12 of the pump 10 . It is even possible for the pump 10 to be operated with the direction of rotation inverted ("speed n<0"). In this case, the pump 10 continues to consume energy since it is actively attempting to pump coolant 7 back.

If the pump 10 is operated in some operating states with the direction of rotation inverted, preferably as shown in FIG 9 between the pump 10 and the application device 6, a check valve 16 or a check valve is arranged. The check valve 16 or the check flap can work purely passively. The non-return valve 16 or the non-return flap can be acted upon, for example, by a slight spring force, so that although they are biased toward the closed position, they open at a very low pressure. The check valve 16 or the check flap does not have to be actively controlled by the control device 11 . The non-return valve 16 or the non-return flap in particular prevent the supply line 8 between the pump 10 and the application device 6 from running empty when the direction of rotation is inverted. In this case, after any closing of the shut-off device 13, the pump 10 can be switched off as soon as the shut-off device 13 is closed, ie further flow of the coolant 7 is blocked. Since the shut-off device 13 does not have to slow down the flow of the coolant 7, but only closes when the flow of coolant 7 has already stopped or is at least essentially stopped, a comparatively simple embodiment of the shut-off device 13 is sufficient. Furthermore, such a non-return valve 16 or such a non-return flap is also necessary when an application device 6 arranged above the rolling stock 1 is fed via the pump 10 . Otherwise the coolant 7 would flow backwards through the pump 10 into the reservoir 9 at a speed of 0. As a result, a buffer area of the application device 6 could become empty. The buffer area would then only have to be filled again when the pump 10 is switched on again. This would increase the effective response time of the applicator 6, which - of course - is not desirable.

If the coolant 7 is made available to the pump 10 without pressure on the input side, the pump 10 can have conventional impellers. On the other hand, if the coolant 7 has an admission pressure, for example 1 bar, the pump 10 can be designed in such a way that the coolant 7 cannot simply flow through when the pump 10 is at a standstill. In this case, the pump 10 must be designed in such a way that it is at least largely sealed when it is at a standstill. Alternatively, the pump 10 can be designed in such a way that it can also be operated in reverse. In the latter case in particular, it makes sense to actuate the shut-off device 13 after the actual current F has been reduced to 0. In particular, in cases where the coolant 7 has a pre-pressure, the above in connection with 9 explained modes of operation makes sense.

As already mentioned, it is possible for the pump 10 to be controlled purely. Preferably, however, as shown in FIG 4 the input-side pressure pE of the liquid coolant 7 is recorded upstream of the pump 10 and fed to the control device 11 . In this case considered the control device 11 detects the pressure pE on the input side when determining the target control state of the pump 10. In many cases, recording the water level in the reservoir 9 is equivalent to a pressure measurement FIG 4 shown, it is also possible to also record the pressure pA on the outlet side behind the pump 10 and to feed it to the control device 11 . In this case, the control device 11 also takes into account the detected pressure pA on the outlet side when determining the setpoint control state of the pump 10.

It is possible for the setpoint current F* to be specified directly and immediately for the control device 11 . However, the control device 11 preferably knows the thermodynamic energy state H of the rolling stock 1 immediately before it reaches the application device 6 . The thermodynamic energy state H can in particular be the enthalpy or the temperature of a respective section of the rolling stock 1 . In this case, the control device 11 determines in accordance with the illustration in 10 first the target current F* as a function of the thermodynamic energy state H and then the associated target control state S* based on the target current F*. In particular, it is possible for the control device 11 to be specified with a local or time-related setpoint profile of the thermodynamic energy state H, which should be adhered to as far as possible. The control device 11 can therefore determine which thermodynamic energy state H should be present directly behind the application device 6 . By comparing it with the actual thermodynamic energy state H immediately in front of the application device 6, the control device 11 can therefore determine what quantity of coolant 7 must be applied to the corresponding section of the rolling stock 1 so that the actual thermodynamic energy state H immediately behind the application device 6 corresponds to the desired target state corresponds as closely as possible. The required amount of coolant 7 then defined in connection with the time which of the corresponding section of the rolling stock 1 required to pass through the application device 6, the target current F*.

All of the procedures explained above in connection with one of the application devices 6 and its associated components can also be carried out for the other application devices 6 in a completely analogous manner. As already mentioned, the procedure mentioned is also carried out for one section of the rolling stock 1 in each case.

The thermodynamic energy state H of the corresponding portion of the rolling stock 1 varies from application device 6 to application device 6. In particular, it is changed by each of the application devices 6. For the application device 6, which first applies its share of coolant 7 to the rolling stock 1, the thermodynamic energy state H of the control device 11 can be specified as such. For example, as shown in FIG 1 A temperature measuring station 17 can be arranged on the inlet side of the cooling section 2, by means of which the temperature T is recorded for the individual sections of the rolling stock 1 in each case. The recorded temperature T is then assigned to the respective section.

Path tracking is implemented for each section as it passes through the cooling line 2 . However, the corresponding thermodynamic energy state H of the rolling stock 1 (or the corresponding section of the rolling stock 1) must be updated for each additional application device 6 that later applies its share of coolant 7 . The control device 11 takes into account in particular the thermodynamic energy state H immediately before the immediately preceding application device 6 and the quantity of coolant 7 which the immediately preceding application device 6 applies to the rolling stock 1 . With regard to the quantity of coolant 7, the control device 11 can alternatively take into account the target current F* or the actual current F of the immediately preceding application device 6. She investigates ie sequentially one after the other for the application devices 6 the thermodynamic energy state H of the rolling stock 1. If required, the control device 11 can apply a heat conduction equation and a phase transformation equation in this context and solve iteratively.

In many cases, the rolling stock 1 is a flat rolling stock, for example a strip or a heavy plate. In this case, it is possible for the liquid coolant 7 to be applied to the rolling stock 1 from both sides by means of each individual application device 6 . This procedure is often taken at a cooling line 2, which is arranged upstream of the rolling train or in the rolling train. However, it can also be taken if the cooling section 2 is arranged downstream of the rolling train. In particular when the cooling section 2 is arranged downstream of the rolling train, the liquid coolant 7 is generally applied to the rolling stock 1 from only one side by means of each individual application device 6, in particular from above or below. Of course it is also possible in this case to apply coolant 7 to both sides of the flat rolling stock 1 . In this case, however, this is done by different application devices 6, each of which is assigned its own pump 10, the pump 10 being controlled independently of the pumps 10 of the other application devices 6.

In the extreme case, it is possible that the application devices 6 each have only a single spray nozzle 18 . As a rule, however, the application devices 6 each have a plurality of spray nozzles 18 . The spray nozzles 18 can, as shown in 11 seen in the transport direction x of the rolling stock 1 can be arranged one behind the other. The spray nozzles 18 can, for example, be arranged one behind the other within a single spray bar 19 . Several spray bars 19 arranged one behind the other in the transport direction x can also be combined to form one (1) application device 6 . This applies regardless of whether the respective spray bar 19 as such several in a row arranged spray nozzles 18 or not. It is decisive in any case that each application device 6 is supplied with coolant 7 individually via its own supply line 8 to its own pump 10, with the pump 10 being controlled individually for setting the respective actual current F.

The application devices 6 can be used as shown in 12 furthermore often have a plurality of spray nozzles 18 which are arranged next to one another seen transversely to the transport direction x of the rolling stock 1 . Such an embodiment can be useful in particular for a flat rolling stock 1, ie for a strip or a heavy plate. In this case, the application devices 6 can extend over the full width of the rolling stock 1 . Alternatively, it is possible for the application devices 6 to only extend over part of the width. This is purely exemplary in the left part of 12 shown for a spray bar 19, which - is divided into three application devices 6 in its width - purely by way of example. In this case, a plurality of application devices 6 are arranged next to one another, each of which is supplied with coolant 7 via its own supply line 8 and its own pump 10, the pumps 10 being controlled independently of one another.

The present invention has many advantages, some of which are listed below.

Since the supply of coolant 7 is not shut off, there are no water hammers when the amount of coolant 7 is abruptly reduced. Switching off is possible in the range of a few tenths of a second (often under 0.2 s, sometimes even under 0.1 s). The same applies when the conveyed quantity of coolant 7 is increased. The actual flow F of the respective application device 6 can also be set correspondingly quickly. The drives 12 for the pumps 10 can be controlled very precisely. A usual accuracy of the speed n is in the range of 0.1%. With the same or a similar The actual current F for the respective application device 6 can also be set with accuracy. Taking into account the response behavior of the drives 12, in all probability a tracking of the actual flux F with an accuracy of 1% can be achieved in less than 0.5 s, possibly even in 0.2 s to 0.3 s.

If the coolant 7 is made available to the pumps 10 without pressure on the inlet side, particularly fast control times can be achieved. Here is a numerical example: Assume that the distance between the reservoir 9 and one of the application devices 6 and thus the length of the associated supply line 8 is a perfectly normal length of 10 m. Flow velocities in the supply line 8 at maximum flow are normally around 3 m/s. If such a quantity of liquid is accelerated with a pressure of 2 bar, an acceleration of 20 m/s ² results. With such an acceleration one can accelerate the amount of liquid from 0 to maximum flow with a time constant of 150 ms. If the pressure increase by the pump 10 is suddenly reduced to 0, the amount of liquid drops back to zero with a time constant of 150 ms, since the application device 6 initially opposes the flow with 2 bar counter-pressure. In this way, extremely fast adjustment times result, which are not even remotely achievable in the prior art. The regulation is even faster if the pump 10 not only reduces the pressure increase to zero, but even actively brakes the liquid quantity.

If the coolant 7 is supplied to the pumps 10 - with or without admission pressure - on the input side via a common pipeline, the pumps 10 are coupled on the input side. In this case, the acceleration of the effective liquid column in this common pipeline must also be taken into account. This can have effects in particular when many of the pumps 10 are to be started up or shut down simultaneously. In practice, however, this condition rarely occurs, so that the problem is tolerable. In addition, the problem can be avoided by appropriate anticipatory control of the pumps 10 .

The cooling section 2 according to the invention can be operated with low energy consumption. For example, some of the application devices 6 can be designed as conventional underside intensive cooling beams with a spraying height of 20 m, which apply the coolant 7 to the rolling stock 1 from below. In this case, the corresponding application device 6 can be operated with an assumed quantity of coolant 7 of 360 m ³ /h with a pump 10 with a rated output of 25 kW. Because 360 m ³ /h corresponds to 0.1 m ³ /s. A spray height of 20 m corresponds to an operating pressure of 2 bar, i.e. 200 kPa. The mechanical power for conveying such an actual flow F is thus 0.1 m ³ /sx 200 kPa = 20 kW. Even with an efficiency of only 80%, a pump output of 25 kW is completely sufficient. In the case of prior-art intensive cooling, on the other hand, around double the pressure is used. Similar figures result for top-side intensive cooling.

The energy saving is even greater if the respective application device 6 is operated with a smaller amount of water. With conventional intensive cooling, the amount of water is reduced by closing a valve. The pressure (4 bar) is maintained, the pump 10 often continues to run with the full flow rate. In the case of the cooling section 2 according to the invention, on the other hand, the speed n of the pump 10 is simply reduced. In this case, with half the amount of water, the spray height is only 5 m. So only half the amount has to be pumped with a quarter of the spray height. This means that only 1/8 of the full power is required, i.e. a little over 3 kW. With the intensive cooling of the prior art, on the other hand, around 25 kW must still be expended.

The wear on pumps 10 and drives 12 is low. Typical service lives for pump bearings are 100,000 hours and more. This allows the pumps 10 to run continuously for over 11 years without the need for maintenance. The cooling section 2 according to the invention is therefore very fail-safe and requires almost no maintenance with regard to the pumps 10 and the drives 12 .

Another advantage that results is a very flexible operation of the cooling section 2. In particular, one and the same application devices 6 can be used and operated as intensive cooling or as laminar cooling as required. The usable control range is usually between 5% and 100% of the maximum amount of coolant that can be pumped.

Equipping the cooling section 2 with the required number of pumps 10 and associated drives 12, including the associated drive controls, requires a certain investment. However, this one-time investment is compensated for relatively quickly by the lower operating costs and increased system availability. In addition, the costs are put into perspective when you consider that considerable costs are also incurred for a conventional cooling section when using high-quality ball valves. Here's an estimate: In a cooling line with 100 upper spray bars 19 and 100 lower spray bars 19, each of which is individually controlled with a respective ball valve, costs of around £700,000 are incurred for the ball valves. For the same amount, one could also build a cooling section 2 according to the invention, in which 100 upper spray bars are supplied via 50 pumps 10 and 100 lower spray bars are supplied via 50 lower pumps. Despite the smaller number of spray bars 19 that can be controlled individually, there is still superior cooling because the spray bars 19 can be controlled with significantly higher dynamics.

In the case of intensive cooling, the costs for the cooling section 2 according to the invention are in the same order of magnitude as the costs for conventional intensive cooling. For example, with 16 upper and 16 lower spray bars 19, a total of 32 relatively small pumps 10 and the associated drives 12, each with 25 kW and a total electrical output of 800 kW, are required. In contrast, there is an investment in a conventional cooling section in 32 ball valves, 32 pneumatic servomotors, 5 booster pumps of 400 kW each (one pump is a reserve) and 5 correspondingly large frequency converters.

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

Reference List

1

rolling stock

2

cooling line

3 to 5

roll stands

6

application devices

7

coolant

8th

supply lines

9

reservoir

10

pump

11

control device

12

drives

13

shut-off device

14

return line

15

Valve

16

check valve

17

temperature measuring station

18

spray nozzles

19

spray bar

E

energy

f

actual current

F*

target current

Fmax

maximum current

f min

minimum current

H

thermodynamic energy state

n

rotational speed

nmin

minimum speed

n max

maximum speed

p0

Pressure in the applicator

pA

downstream pressure

PE

input pressure

S*

control state

t

time

t1 to t4

times

x

transport direction

Claims (18)

1. Method for operating a cooling section (2) which is arranged within a rolling train or upstream or downstream of the rolling train and by means of which a hot-rolled product (1) made of metal is cooled,

   - wherein a number of application devices (6) of the cooling section (2) are supplied with a respective actual flow (F) of a liquid, water-based coolant (7) via a respective supply line (8) and a respective pump (10),

   - wherein the respective actual flow (F) of the coolant (7) is applied to the hot-rolled product (1) by means of the respective application device (6),

   - wherein the hot-rolled product (1) is transported in a horizontal transport direction (x) within the cooling section (2) during the application of the coolant (7),

   characterized
   in that a controller (11) of the cooling section (2) dynamically determines a respective target control state (S*) for the respective pump (10) on the basis of a respective target flow (F*) of the coolant (7) to be applied to the hot-rolled product (1) by means of the respective application device (6) and controls the respective pump (10) in a corresponding manner such that the respective actual flow (F) delivered by the respective pump (10) is approximated as far as possible to the respective target flow (F*) at any time.
2. Operating method according to Claim 1,

   characterized

   in that

   - either no shutoff device (13) is arranged between the respective pump (10) and the respective application device (6),

   - or, although a shutoff device (13) is arranged between the respective pump (10) and the respective application device (6), the shutoff device (13) is kept permanently in the fully open state during the transport of the rolled product (1) through the cooling section (2),

   - or, although a shutoff device (13) is arranged between the respective pump (10) and the respective application device (6), the shutoff device (13) is actuated both in the opening and in the closing direction only when a speed of the respective pump (10) is below a minimum speed.
3. Operating method according to Claim 2,
   characterized
   in that the respective pump (6) is assigned a return line (14) in parallel, and in that the return line (14) has a smaller cross section than the respective supply line (8).
4. Operating method according to Claim 1, 2 or 3,
   characterized
   in that the respective pump (10) is operated as a generator or operated with a reverse direction of rotation whenever the respective target flow (F*) falls below a respective lower limit value.
5. Operating method according to Claim 4,
   characterized
   in that a check valve (16) or a swing check valve is arranged in the respective supply line (8) between the respective pump (10) and the respective application device (6).
6. Operating method according to any of the preceding claims,
   characterized
   in that an inlet-side pressure (pE) of the liquid coolant (7) is sensed upstream of the respective pump (10), and in that the controller (11) takes the sensed inlet-side pressure (pE) into account when determining the respective target control state (S*) of the respective pump (10).
7. Operating method according to any of the preceding claims,
   characterized
   in that an outlet-side pressure (pA) of the liquid coolant (7) is sensed downstream of the respective pump (10), and in that the controller (11) takes the sensed outlet-side pressure (pA) into account when determining the respective target control state (S*) of the respective pump (10).
8. Operating method according to any of the preceding claims,
   characterized
   in that the controller (11) determines the respective target flow (F*) on the basis of a respective thermodynamic energy state (H) of the rolled product (1) pertaining immediately before the respective application device (6) is reached.
9. Operating method according to any of the preceding claims,
   characterized

   - in that the actual flows (F) of the coolant (7) are applied to the hot-rolled product (1) sequentially in succession by means of the application devices (6), and

   - in that the controller (11) determines the respective thermodynamic energy state (H) of the rolled product (1) from the thermodynamic energy state (H) of the rolled product (1) upstream of the immediately preceding application device (6) while additionally taking into account the target flow (F*) of the coolant (7) or the actual flow (F) of the coolant (7) which is applied or is intended to be applied to the hot-rolled product (1) by means of the immediately preceding application device (6) .
10. Cooling section which can be arranged within a rolling train or upstream or downstream of the rolling train and by means of which a hot-rolled product (1) made of metal is cooled,

    - wherein the cooling section has a number of application devices (6), which are supplied with a respective actual flow (F) of a liquid, water-based coolant (7) via a respective supply line (8) of the cooling section and a respective pump (10) of the curling section,

    - wherein the respective actual flow (F) of the coolant (7) is applied to the hot-rolled product (1) by means of the respective application device (6),

    - wherein the hot-rolled product (1) is transported in a horizontal transport direction (x) in the cooling section during the application of the coolant (7),

    - wherein the cooling section has a controller (11),

    characterized
    in that the controller (11) is configured such that it dynamically determines a respective target control state (S*) for the respective pump (10) on the basis of a respective target flow (F*) of the coolant (7) to be applied to the hot-rolled product (1) by means of the respective application device (6) and controls the respective pump (10) in a corresponding manner such that the respective actual flow (F) delivered by the respective pump (10) is approximated as far as possible to the respective target flow (F*) at any time.
11. Cooling section according to Claim 10,

    characterized

    in that

    - either no shutoff device (13) is arranged between the respective pump (10) and the respective application device (6),

    - or, although a shutoff device (13) is arranged between the respective pump (10) and the respective application device (6), the shutoff device (13) is kept permanently in the fully open state by the controller (11) during the transport of the rolled product (1) through the cooling section (2),

    - or, although a shutoff device (13) is arranged between the respective pump (10) and the respective application device (6), the shutoff device (13) is actuated by the controller (11) both in the opening and in the closing direction only when a speed of the respective pump (10) is below a minimum speed.
12. Cooling section according to Claim 11,
    characterized
    in that the respective pump (6) is assigned a return line (14) in parallel, and in that the return line (14) has a smaller cross section than the respective supply line (8).
13. Cooling section according to Claim 10, 11 or 12,
    characterized
    in that the respective pump (10) is controlled by the controller (11) such that it is operated as a generator or operated with a reverse direction of rotation whenever the respective target flow (F*) falls below a respective lower limit value.
14. Cooling section according to Claim 12,
    characterized
    in that a check valve (16) or a swing check valve is arranged in the respective supply line (8) between the respective pump (10) and the respective application device (6).
15. Cooling section according to any of Claims 10 to 14,
    characterized
    in that means for sensing the inlet-side pressure upstream of the respective pump (10) are provided, in that an inlet-side pressure (pE) of the liquid coolant (7) is sensed upstream of the respective pump (10), and in that the controller (11) takes the sensed inlet-side pressure (pE) into account when determining the respective target control state (S*) of the respective pump (10).
16. Cooling section according to any of Claims 10 to 15,
    characterized
    in that means for sensing the outlet-side pressure downstream of the respective pump (10) are provided, in that an outlet-side pressure (pA) of the liquid coolant (7) is sensed downstream of the respective pump (10), and in that the controller (11) takes the sensed outlet-side pressure (pA) into account when determining the respective target control state (S*) of the respective pump (10).
17. Cooling section according to any of Claims 10 to 16,
    characterized
    in that the controller (11) determines the respective target flow (F*) on the basis of a respective thermodynamic energy state (H) of the rolled product (1) pertaining immediately before the respective application device (6) is reached.
18. Cooling section according to Claim 17,
    characterized

    - in that the actual flows (F) of the coolant (7) are applied to the hot-rolled product (1) sequentially in succession by means of the application devices (6), and

    - in that the controller (11) determines the respective thermodynamic energy state (H) of the rolled product (1) from the thermodynamic energy state (H) of the rolled product (1) upstream of the immediately preceding application device (6) while additionally taking into account the target flow (F*) of the coolant (7) or the actual flow (F) of the coolant (7) which is applied or is intended to be applied to the hot-rolled product (1) by means of the immediately preceding application device (6) .

Images