JP2023525657A - Operating the cooling unit with minimum operating pressure - Google Patents

Abstract

Liquid coolant (6) is supplied to the header line (4) using a pump assembly (5). Branch lines (9a to 9d), in which control valves (11a to 11d) are arranged, branch from the header line (4) to the application units (10a to 10d). The coolant (6) is applied to the metallic hot rolled stock (2) using application units (10a to 10d), whereby the rolled stock (2) is cooled. For the limit modulation value (kLim) of the control valves (11a to 11d), the control unit (12) of the cooling unit (3) uses the setpoint flow rate (Ka* to Kd*) of the application unit (10a to 10d). to determine the individual operating pressures (pAa to pAd) that must prevail in the header lines (4) in order for the setpoint flows (Ka* to Kd*) to flow into the branch lines (9a to 9d). An interim operating state (Z) of the pump assembly (5) is then determined so that the sum of the set point flow rates (Ka* to Kd*) is supplied to the header line (4) while at the same time at least the individual A temporary operating pressure (pAv), corresponding to the maximum operating pressure (pAa to pAd) of , prevails in the header line (4). Using an interim operating state (Z) such that the total flow rate (K) is supplied to the header line (4) while at the same time the final operating pressure (pAe) prevails in the header line (4), Determine the final operating state (Z') of the pump assembly (5). The final operating pressure (pAe) is then used to determine the operating values (Aa to Ad) of the control valves (11a to 11d) so that the setpoint flow rates (Ka* to Kd*) 9d) flow in. This causes the pump assembly (5) and control valves (11a to 11d) to operate accordingly.

Description

The invention begins with a method of operating a cooling unit for cooling metallic hot-rolled stock,
- the cooling unit has a header line to which the liquid coolant is supplied using a pump assembly, from which a plurality of branch lines branch off to the application unit;
- the pump assembly has several pumps, a control valve is arranged in each of the branch lines, the coolant is applied to the rolled stock using at least some of the application units,
- the setpoint flow to be supplied to the application unit is communicated to the control unit of the cooling unit;
- The control unit operates the pump assembly according to the final operating state and the control valve according to the operating value.

The invention further begins with a computer program comprising machine code executable by a control unit of a cooling unit for cooling a metallic hot-rolled material, the machine code being executed by the control unit causing the control unit to operates the cooling unit according to this type of operating method.

The invention further begins with a control unit of a cooling unit for cooling a metallic hot-rolled material, the control unit being programmed by a computer program of this kind so that the control unit can Operate the cooling unit according to

The invention further begins with a cooling unit for cooling a metallic hot-rolled material,
- the cooling unit has a header line, a pump assembly and a plurality of application units,
- a liquid coolant is applied to the rolling stock using at least some of the application units;
- the application units are connected to the header line via respective branch lines,
- the pump assembly comprises several pumps by means of which liquid coolant is supplied to the header lines;
- a control valve is arranged in each of the branch lines,
- The cooling unit has such a control unit that operates the cooling unit according to such an operating method.

The above subject matter is common knowledge.

For example, US Pat. No. 5,300,000 discloses a cooling unit for cooling metallic hot-rolled stock, in which liquid coolant is supplied to a header line using a pump assembly and branches off therefrom. A line branches off to an application unit by which the coolant is applied to the rolling material. A control valve is positioned in the branch line. Based on the setpoint flow rate known to the control unit and to be supplied to the application unit, the control unit determines the operational state of the pump assembly and the operational values of the control valves and operates the pump assembly and control valves accordingly. . In US Pat. No. 5,400,000, the header line is either under high pressure or under low pressure. Higher pressure of coolant is created only when it is actually needed. A high pressure requirement is considered to exist if, at low pressure, the open position of at least one valve exceeds a certain open position specified as a limit value.

WO 2005/020000 likewise discloses a cooling unit for cooling metallic hot-rolled stock, in which liquid coolant is supplied by means of a pump assembly to a header line and from there A branch line branches off to an application unit whereby coolant is applied to the rolling material. A control valve is positioned in the branch line. The setpoint flow to be supplied to the application unit is communicated to the control unit of the cooling unit. The control unit determines corresponding operating values for the control valves and also operates the control valves in this manner. There is no description of the (optionally variable) operation of the pump in US Pat.

US Pat. No. 6,200,000 similarly discloses a cooling unit for cooling metallic hot-rolled stock, in which liquid coolant is supplied by means of a pump assembly to a header line and from there A branch line branches off to an application unit whereby coolant is applied to the rolling material. A control valve is positioned in the branch line. The control unit of the cooling unit determines the total flow based on the setpoint flow to be supplied to the application unit and determines the operational state of the pump assembly based on the total flow. The header line operating pressure can be set between a minimum and maximum value. The control valve can be adjusted between fully closed and fully open positions. To set individual set point flow rates, the control unit varies both the open position of the valve and the line pressure that the pump produces in the header line.

US Pat. No. 5,300,009 similarly discloses a cooling unit for cooling metallic hot-rolled stock, in which liquid coolant is supplied by means of a pump assembly to a header line and from there A branch line branches off to an application unit whereby coolant is applied to the rolling material. A control valve is positioned in the branch line. The control unit determines operating conditions for the pump assembly in response to the setpoint flow rate to be supplied to the application unit. The control unit takes into account changes in water volume and line resistance in addition to the total amount of water supplied. The operating state of the pump, and thus also the operating pressure, is adapted if the open position of the control valve is below the minimum possible open position and the minimum distance from the maximum possible open position.

US Pat. No. 5,300,009 discloses a cooling unit for cooling a metallic hot rolled stock, in which a liquid coolant is applied to the rolled stock by means of a plurality of application units. The application units are each fed with a dedicated pump. The valves between each pump and each application unit are continuously kept fully open. The amount of coolant delivered is set only by the corresponding time-varying operation of the pump.

WO2013/143925 WO2014/124867 WO2014/124868 WO2019/115145 WO2020/020868

Particularly in the case of centralized cooling, but sometimes also in the case of laminar cooling, the control valves are fed by means of pumps. In this case, a typical configuration is the supply of multiple control valves via header lines, which are supplied with coolant by a pump assembly. The pump assembly can have a single pump or multiple pumps.

The coolant is applied to the rolling stock using an application unit (often designed as a spray bar). In some cases there may be an additional application unit that does not apply the coolant to the rolled material but releases the coolant elsewhere. This is useful, for example, to make the amount of coolant delivered more uniform overall.

It is an object of the present invention to provide a method by which a conventional cooling unit, i.e. a cooling unit in which the coolant applied to the rolling stock is metered through the action of a control valve, can be operated in an improved manner. is.

The object is achieved with an operating method having the features of claim 1 . Advantageous refinements form the subject matter of dependent claims 2-5.

According to the invention, a method of operation of the first-mentioned type is provided in which the control unit - controls for the respective limit modulation values of the respective control valves, in order to determine the final operating state of the pump assembly and the operating values of the control valves. determining the respective individual operating pressures of the valves, which operating pressures must prevail in the header lines so that the respective set point flow flows in the respective branch lines;
- determine the interim operating state of the pump assembly so that a total flow of coolant corresponding to the sum of the set point flows is supplied to the header line with the pump assembly and, at the same time, out of the individual operating pressures; ensuring that an interim operating pressure predominates in the header line that is at least as high as the maximum pressure of
- Using the interim operating state of the pump assembly, the final operating state of the pump assembly is used such that the total flow of coolant is supplied to the header line using the pump assembly while the final operating pressure prevails in the header line. determining an operating state;
- configured to use the final operating pressure to determine the operating values of the control valves so that the respective set point flow flows into the respective branch lines;

This ensures that the pump assembly of the cooling unit is operated at the lowest possible final operating pressure and therefore with the lowest possible energy consumption, nevertheless the rolled material is always cooled according to the required set point flow rate. to

The limit adjustment of the control valve can be the maximum adjustment of the control valve. However, in order to obtain a constant control reserve, it may be advantageous if the limit adjustment of the control valve is slightly below this, ie very close to the maximum adjustment of the control valve. In the latter case, the limit adjustment of the control valve thus corresponds to a high percentage of the maximum adjustment of the control valve, eg 80%, 90% or 95%. Of course, the limit adjustment can also have other values. In particular, however, the value of 80% should not be reached. Numerical data also relate to the coolant flow rate, the effect resulting from the operation of the respective control valve. On the other hand, they are independent of the manipulated variable with which the control valve is operated. Limit adjustments can be individually specified for each control valve as desired or can be specified uniformly for all control valves. It is also possible to specify in group units.

As part of determining the interim operating state, the control unit preferably considers secondary conditions related to the pump assembly. This makes it possible to ensure that the pump assembly is always operating within an acceptable operating range. The control unit can, for example, check whether it is able to determine an acceptable operating state of the pump assembly, which on the one hand delivers the total flow required and on the other hand the determined flow rate in the header line. of the individual operating pressures. In that case, this operating pressure or a value derived directly from this operating pressure can be used as the final operating pressure. If not, the control unit can step up the operating pressure, starting with an interim operating pressure, until an acceptable operating condition for the pump assembly is found.

As part of determining the interim operating state, the control unit preferably considers secondary conditions related to the control valve. For example, an acceptable operation of a pump assembly that, on the one hand, delivers the total flow required and, on the other hand, produces an operating pressure in the header line that is at least as high as the maximum of the individual operating pressures. For conditions, it is possible for the control unit to determine the relevant operating values of the control valves to ascertain whether, and if so to what extent, undesired conditions occur. Either the undesired state can then be accepted or the operating state of the pump assembly can be adapted. The action to be taken can be decided on a case-by-case basis.

As part of determining the final operating state of the pump assembly, the control unit preferably additionally determines at least one previous final operating state of the pump assembly and/or at least one interim operation of the pump assembly anticipated in the future. Consider the state. For example, the control unit may perform a model-predictive determination of interim operating conditions. The control unit can also set optimization problems, for example involving the minimization according to the invention of the interim operating pressure on the one hand and further situations on the other hand. Examples of such situations are changes in interim or final operating pressure and changes in the operating state of the pump assembly.

The object is further achieved with a computer program having the features of claim 6. According to the invention, execution of the computer program has the effect of operating the cooling unit according to the operating method according to the invention on the control unit.

The object is further achieved with a control unit having the features of claim 7 . According to the invention, the control unit is programmed with the computer program according to the invention, so that the control unit operates the cooling unit according to the operating method according to the invention.

The object is achieved with a cooling unit for cooling metallic hot-rolled stock having the features of claim 8 . According to the invention, a cooling unit of the first-mentioned kind has a control unit according to the invention for operating the cooling unit according to the operating method according to the invention.

The above-described properties, features, and advantages of the present invention, as well as the manner in which these are achieved, are described in greater detail in conjunction with the following description of illustrative embodiments in conjunction with the drawings. , will be understood more clearly and distinctly. It is shown below as a schematic diagram here.

1 shows a rolling line with a first cooling unit; FIG. It is a figure which shows the characteristic curve of a control valve. It is a flow chart. FIG. 4 is a diagram showing a characteristic curve of a pump; It is a flow chart. Fig. 10 shows a pump assembly; It is a flow chart. It is a flow chart.

According to FIG. 1 the rolling line has at least one rolling stand 1 . FIG. 1 shows only a single rolling stand 1 . However, in many cases a plurality of rolling stands 1 are arranged in series and the rolling line is therefore designed as a rolling mill train. In the rolling line the hot rolled material 2 is rolled, ie its cross section is reduced. The rolling stock 2 can consist, for example, of steel or aluminium. However, it can also consist of other metals, such as brass or copper. The rolling stock 2 can be, for example, a strip-shaped or plate-shaped flat rolling stock. However, it may also be rod-shaped or have other shapes designed as a cross-sectional shape or as a tube.

The rolling line also has a cooling unit 3 . According to the illustration of FIG. 1 , the cooling unit 3 is arranged downstream of the rolling stand 1 . However, this is not absolutely necessary. The cooling unit 3 may likewise, for example, be in the form of a so-called inter-stand cooling means between the finishing stands of a multi-stand finishing train or roughening between the first finishing stand of a multi-stand finishing train and the roughing mill. It can be arranged upstream of the rolling stand 1 in the form of strip cooling means. Other arrangements are also possible.

The cooling unit 3 has a header line 4 . Liquid coolant 6 is supplied to header line 4 using pump assembly 5 . For this purpose the pump assembly 5 can be connected to the reservoir 7, for example on the inlet side. However, other embodiments are also possible, for example a direct supply of the pump assembly 5 via the water network. According to the illustration of FIG. 1 , the pump assembly 5 can comprise multiple pumps 8 . In the embodiment according to FIG. 1, the pumps 8 are connected in parallel with each other. However, the pumps 8 can also be arranged in series with each other. A combination of this approach, for example three lines, is also possible, and in each line two pumps 8 are arranged in series with each other. It is also possible that only a single pump 8 is present. Coolant 6 is typically water or consists at least substantially (98% or more) of water.

Branch lines 9a to 9d branch from header line 4 to application units 10a to 10d. Application units 10a to 10d are thus connected to header line 4 via branch lines 9a to 9d. The coolant 6 is applied to the rolling stock 2 by means of application units 10a to 10d. Application units 10a to 10d can be designed, for example, as so-called cooling bars or spray bars.

According to the illustration of FIG. 1, the application units 10a to 10d are arranged above the rolled stock 2 so that they apply the coolant 6 to the rolled stock 2 from above. However, this is not absolutely necessary. The application units 10a to 10d can likewise be arranged below the rolling stock 2 or arranged elsewhere. It is also possible that the application units 10a to 10d apply the coolant 6 to the rolled stock 2 from different sides. Also, not all of the application units 10a to 10d apply the coolant 6 to the rolling stock 2, but at least one (and then typically one or two) of the application units 10a to 10d applies the coolant 6. It is also possible not to apply it to the rolled material 2 . A corresponding embodiment and the reasons for this are described, for example, in US Pat.

Furthermore, a total of four application units 10a to 10d are illustrated in FIG. The invention will be described in conjunction with this number of application units 10a to 10d. However, the number of application units 10a to 10d may be greater or less. It should be greater than 1. There are therefore at least two application units 10a to 10d connected to the header line 4 via two branch lines 9a to 9d, in each of which a control valve 11a to 11d is arranged.

A control valve 11a to 11d is arranged in each of the branch lines 9a to 9d. The control valves 11a to 11d can be designed as ball valves, for example. However, regardless of their specific design, control valves 11a to 11d may be continuously regulated. The term "continuously regulating" is explained below with reference to the illustration of FIG. 2 for the control valve 11a. Similar statements apply to control valves 11b to 11d.

According to FIG. 2, control valve 11a is operated with actuation value Aa. The operating value Aa lies between a minimum operating value Amin and a maximum operating value Amax. The operating value Aa can be changed continuously or at least in steps. Accordingly, the operating value Aa can assume a plurality of possible values (optionally within the adjustment accuracy) between the minimum operating value Amin and the maximum operating value Amax. For example, for a ball valve, the minimum operating value Amin and the maximum operating value Amax may be 0° and 90°, the operating value Aa between these two extremes Amin, Amax, for example 0.1 ° or 0.2° steps.

At a reference pressure pR present on the inlet side of the control valve 11a, a corresponding reference coolant flow rate KR flows through the control valve 11a and thus through the corresponding branch line 9a, depending on the operating value Aa. Since it is possible to adjust the control valve 11a continuously, the reference coolant flow rate KR is the correspondence between a minimum value KRmin (usually 0) and a maximum value KRmax (which is of course greater than the minimum value KRmin). through a continuous range of values. The reference coolant flow rate KR divided by the maximum value KRmax corresponds to the modulation ka of the control valve 11a. Modulation ka has a maximum value of 1 and typically has a minimum value of 0.

The functional relationship of the reference coolant flow rate KR (or equivalently the modulation ka) as a function of the operating value Aa corresponds to the characteristic curve of the control valve 11a. As illustrated in FIG. 2, the characteristic curve is often non-linear. However, there is usually a strictly monotonic relationship between one operating value Aa and either the reference coolant flow rate KR or the modulation ka. Also, as known to those skilled in the art, at a given operating value Aa, assuming that the operating pressure pA present at the inlet side of the control valve 11a is known, the actual coolant flow rate Ka, i.e. The amount of coolant 6 that actually flows through control valve 11a, can easily be determined. In particular, the values obtained from the characteristic curve itself need only be scaled by the square root of the quotient of the operating pressure pA and the reference pressure pR. Also, the operating pressure pA and the reference pressure pR may have to be corrected by an offset. Given a given modulation ka and a known maximum reference coolant flow rate KRmax and a known operating pressure pA, the coolant flow rate Ka is given by the equation

becomes.
ρ is the density of the coolant 6, g is the acceleration due to gravity and ha is the height of the valve outlet (or application unit 10a) with respect to a reference level which is uniform for the application units 10a to 10d. Depending on the placement of the valve outlet with respect to the reference level, hA can be greater or less than zero. The reference level can be selected as desired. For example, this can coincide with the level of the roller table for conveying the rolling stock 2 through the cooling unit 3 . The associated operating value Aa is obtained directly from the characteristic curve after determining the modulation ka.

The cooling unit 3 furthermore has a control unit 12 for controlling and operating the cooling unit 3 . Generally, control unit 12 is designed as a software programmable unit. This is indicated in FIG. 1 by the symbol “μP” for the microprocessor being drawn within the control unit 12 . Control unit 12 is programmed by computer program 13 . Computer program 13 includes machine code 14 that can be executed by control unit 12 . Based on programming by the computer program 13 or execution of the machine code 14, the control unit 12 operates the cooling unit 3 according to the operating method described in more detail below in conjunction with FIG.

In step S 1 , the setpoint flow rates Ka* to Kd* are communicated to the control unit 12 . The set-point flows Ka* to Kd*, for example in units of liters/second, are supplied to the respective application units 10a to 10d and emitted by the respective application units 10a to 10d, in particular the cooling to be applied to the rolled stock 2. The amount of agent 6 is indicated. For example, control unit 12 setpoint flow rates Ka* to Kd* may be specified externally or determined independently by control unit 12 based on other conditions. Suitable procedures are well known to those skilled in the art.

In step S2, the control unit 12 determines the individual operating pressure pAa for the limit modulation value kLim of the control valve 11a. A limit modulation value kLim is specified for the control unit 12 . The limit modulation value kLim may be the maximum modulation of the control valve 11a. However, in many cases, according to the illustration of FIG. 2, a value near but below the maximum modulation of the control valve 11a is advantageous. In this case, the limit modulation value kLim should be at least 80%, preferably at least 90% and particularly preferably at least 95%. However, generally the value of 98% should not be exceeded. The limit modulation value kLim thus corresponds to a high percentage of maximum modulation of the control valve 11a. Formally, it should be clarified that limit modulation value kLim is related to modulation ka of control valve 11a and not to actuation Aa of control valve 11a.

The control unit 12 determines the individual operating pressure pAa such that, at the operating pressure pAa and the limit modulation value kLim of the control valve 11a, the desired setpoint flow rate Ka* flows in the branch line 9a. The control unit 12 determines the operating pressure pAa, for example by the formula

determined according to

In step S3, the control unit 12 determines the individual operating pressures pAb to pAd in a completely analogous way for the control valves 11b to 11d. The limit modulation value kLim, the maximum reference coolant flow rate KRmax and the reference pressure pR of the other control valves 11b to 11d have the same values as the limit modulation value kLim, the maximum reference coolant flow rate KRmax and the reference pressure pR of the control valve 11a. can be done. Alternatively, these may be other values that may vary from control valve 11b to 11d to control valve 11b to 11d also within other control valves 11b to 11d, if appropriate. However, in each case the control unit 12 determines the individual operating pressures pAb to pAd of the other control valves 11b to 11d independently of each other and independently of the individual operating pressure pAa of the control valve 11a.

The control unit 12 then determines the operating state Z of the pump assembly 5 in step S4. The operating state Z is determined such that the pump assembly 5 delivers a total flow rate K corresponding to the sum of the set point flow rates Ka* to Kd*, provided that it is operated according to the operating state Z. As a result of the delivery of total flow K, total flow K of coolant 6 is also supplied to header line 4 using pump assembly 5 . At the same time, the operating state Z is determined such that an operating pressure pAv that is at least as high as the highest of the individual operating pressures pAa to pAd prevails in the header line 4 . However, both the operating state Z and the operating pressure pAv are only provisional. The operating state Z comprises at least the required rotational speed n for each pump 8 of the pump assembly 5 .

In this context it is important that the operation of the pump assembly 5 can be varied continuously or at least in steps. It is therefore not only possible to switch between two or three fixed discrete operating states Z, but the possible operating states Z form a continuous range or a virtual continuous range. Purely by way of example, if one of the pumps 8 can be operated between a minimum rotational speed nmin of 100 rev/min and a maximum rotational speed nmax of 800 rev/min, the rotational speed n is between 100 rev/min and 800 rev/min. /min, for example 150 rev/min, 227 rev/min or 593 rev/min if steplessly adjustable, or at least 10 steps if stepwise adjustable, It can also be set in different steps, for example 100, 150, 200, 250, up to a maximum of 800 revolutions/minute. Of course, the numerical values given should be construed as examples only.

As part of step S4, it is possible for the control unit 12 to consider only the pressure statically generated by the pump assembly 5; Therefore, as part of step S4, it is possible for the control unit 12 to assume that the pressure developed on the outlet side of the pump assembly 8 corresponds to the pressure on the inlet side of the control valves 11a to 11d. However, it is equally possible to take into account additional situations in the control unit 12 . Examples of such situations are the change in setpoint flow rate Ka* to Kd* over time and the associated change in total flow rate K over time and the associated acceleration of water flow. A further example of such a situation is the flow resistance between the pump assembly 5 and the header line 4 or within the header line 4, on the basis of which the pressure generated on the inlet side of the control valves 11a to 11d is always less than the pressure generated by the pump assembly 8. For both situations, US Pat. No. 6,300,001 describes corresponding possibilities for taking them into account. The height difference between the pump assembly 8 on the one hand and the header line 4 or the reference level of the header line 4 on the other hand can further be taken into account with a constant offset.

In the simplest case, where there is only a single pump 8, for example, the control unit 12 directs the pump 8 to produce a certain pressure increase δp at a certain total flow rate K, as shown in the diagram of FIG. It is possible to determine the rotation speed n of said pump by accessing a family of characteristic curves which stores the required rotation speed n of the pump 8 . Together with the suction pressure pS prevailing on the inlet side of the pump assembly 5, the required pressure increase δp=pS−pAv can thus easily be determined. The suction pressure pS may be known to the control unit 12 based on measurements or in some other way.

In many cases, the operating state determined for the maximum of the individual operating pressures pAa to pAd is itself already the permissible operating state of the pump assembly 5 . In this case, this operating state can be taken directly as interim operating state Z. Other possibilities and embodiments are described below.

The control unit 12 then determines the operating state Z' of the pump assembly 5 in step S5. In contrast to the operating state Z, the operating state Z' is final. The control unit 12 uses the interim operating state Z of the pump assembly 5 to determine the final operating state Z' of the pump assembly 5 . The determination in step S5 is such that a total flow rate K of coolant 6 is supplied to header line 4 using pump assembly 5 . At the same time, the final operating pressure pAe prevails in the header line 4, assuming that the pump assembly 5 is operated according to the final operating state Z'. In the simplest case, the control unit 12 directly and immediately assumes the interim operating state Z as the final operating state Z'. It is also possible to increase the interim operating pressure pAv by a very small additive offset, or multiply it by a factor slightly greater than one, thereby determining the final operating pressure pAe. These approaches are similar in effect to using a limit modulation value kLim slightly less than one. Other possibilities and embodiments for determining the final operating pressure pAe are described below.

Final operating state Z' results in a final operating pressure pAe in header line 4, provided that the desired total flow rate K is delivered into header line 4 by pump assembly 8. FIG. The control unit 12 therefore determines the actuation values Aa to Ad of the control valves 11a to 11d in step S6 using the final actuation pressure pAe. This determination is performed such that the respective setpoint flows Ka* to Kd* flow in the respective branch lines 9a to 9d.

As part of the determination in step S6, the control unit 12 assumes that the final operating pressure pAe prevails in the header line 4. For the control valve 11a, for example, the modulation ka is thus

becomes.

The situation is similar for the other control valves 11b to 11d. Based on the currently known modulations ka to kd of the control valves 11a to 11d, it is therefore possible to determine the required operating values As to Ad of the control valves 11a to 11d using the associated characteristic curves. .

In step S7, the control unit 12 operates the pump assembly 5 and the control valves 11a-11d. The pump assembly 5 is operated according to the final operating state Z'. The control valves 11a to 11d are operated according to actuation values Aa to Ad.

By executing step S7, the driving method according to the present invention is executed. However, after performing step S7, control unit 12 generally returns to step S1. That is, the control unit 12 iteratively repeats the series of steps S1 to S7. Generally, execution is performed at a fixed cycle time. A fixed cycle time is typically 0.1 to 1.0 seconds, typically 0.2 to 0.5 seconds, eg about 0.3 seconds.

A possible embodiment of step S4 of FIG. 3, ie a possible method of determining the interim operating state Z, is described below in conjunction with FIG. As part of the embodiment according to FIG. 5, step S4 of FIG. 3 is subdivided into steps S11 to S14.

In step S11, the control unit 12 delivers the total flow rate K and at the same time the required pressure increase δp required to cause the individual operating pressures pAa determined from the suction pressure pS to the maximum pressure pAd up to pAd. Determine the operating state of the pump assembly 5 . For example, if there is only one pump 8 , the control unit 12 can determine the corresponding rotational speed n of the pump 8 .

In step S12 the control unit 12 checks whether the determined provisional state Z is permissible, e.g. whether the determined rotational speed n is within the permissible rotational speed range of the pump 8, i.e. the operating point of the pump 8 is within the non-shaded range in FIG. Checking in this way means checking whether the secondary conditions relating to the pump assembly 5 are met.

It is possible that the rotational speed n is within the permissible rotational speed range of the pump 8 (which is even the normal case). For example, the operating point AP1 of the pump 8 within the permissible speed range of the pump 8 can be determined by the maximum of the total flow K and the individual operating pressures pAa to pAd. If the rotational speed n is within the permissible rotational speed range of the pump 8, the control unit 12 proceeds to step S13. In step S13, the control unit 12 takes no further action. The determined rotational speed n can be used directly.

However, it is equally possible (albeit rare) that the rotational speed n is not within the permissible rotational speed range of the pump 8 . For example, the operating point AP2 or AP3 of the pump 8 can be determined by the maximum of the total flow K and the determined individual operating pressures pAa to pAd. Indeed, for the operating point AP2, the pump 8 can easily generate the maximum of the determined individual operating pressures pAa to pAd. However, due to the allowable speed range of pump 8, the volume flow delivered by pump 8 will necessarily be greater than the total flow K required. For operating point AP3, the situation is reversed. Indeed, the pump 8 can easily generate the total flow K required. However, due to the permissible speed range of the pump 8, a pressure increase .delta.p larger than the required minimum is necessarily produced by the pump 8.

If the rotational speed n is not within the allowable rotational speed range of the pump 8, the control unit 12 proceeds to step S14. In step S14, the control unit 12 modifies the interim operating state Z.

For the operating point AP2, the control unit 12 can, for example, determine an open state for the shunt valve 15 (see FIG. 6). According to the illustration of FIG. 6, the short-circuit valve 15 is connected in parallel with the pump 8 . It can be considered as part of the pump assembly 5 or as a control valve for a further application unit. The control unit 12 ensures that the amount of coolant 6 directly or indirectly returned to the reservoir 7 via the shunt valve 15 is such that the resulting volumetric flow supplied to the header line 4 corresponds to the desired total flow K. to determine the open state, if applicable.

In the case of operating point AP3, the control unit 12 indicates that, for example, only the pump 8 is operated (so that the short-circuit valve 15, if present, remains closed), but at the desired total flow K, provisionally It is possible to modify the interim operating state Z such that the interim operating pressure pAv occurring in the operating state Z is higher than the maximum of the individual operating pressures pAa to pAd. In this case, the interim operating pressure pAv is preferably set to the smallest possible and permissible value.

A further possible embodiment of step S4 of FIG. 3 is described below in conjunction with FIG. As part of the embodiment according to FIG. 7, step S4 of FIG. 3 is subdivided into steps S21 to S24. The procedure of FIG. 7 can be combined with the procedure of FIG. 5 or performed independently therefrom, if desired. When combined, step S21 may be omitted, and steps S22 to S24 are performed after steps S13 and S14, respectively.

In step S21, in a manner analogous to step S11 of FIG. 5, the control unit 12 delivers the total flow rate K and, at the same time, the individual operating pressures pAa determined from the suction pressure pS to the maximum of pAd. Determine the rotational speed n of the pump 8 required to cause the required pressure increase δp of .

In step S22, the control unit 12 checks whether operation of the control valves 11a to 11d is acceptable at the resulting interim operating pressure pAv. The control unit 12 can, for example, check whether the regulating speeds at which the operating values Aa to Ad of the control valves 11a to 11d are changed comply with predetermined limits. Checking in this way means checking whether the secondary conditions relating to the control valve are met.

It is possible (which is even the usual case) that secondary conditions are met. In this case, the control unit 12 proceeds to step S23. At step S23, the control unit 12 takes no further action. The determined rotational speed n can be used directly.

However, it is equally (albeit rare) possible that secondary conditions are not met, for example an excessively high adjustment speed occurs. In this case, the control unit 12 proceeds to step S24. In step S<b>24 , depending on the circumstances of the individual case, the control unit 12 can either accept the exceeding of a given limit or adapt the interim operating state Z of the pump assembly 5 . In particular, in some circumstances, an interim action is required to ensure that the predetermined limit is no longer exceeded, or at least exceeded to a relatively small extent, by a corresponding change in the action of the control valves 11a to 11d. An increase in pressure pAv can be used.

A possible embodiment of step S5 of FIG. 3, ie a possible method of determining the final operating state Z using the interim operating state Z of the pump assembly 5, is described below in conjunction with FIG. As part of the embodiment according to FIG. 8, step S5 of FIG. 3 is replaced by step S41. In step S41, in addition to the provisional operating state Z currently determined in step S4, control unit 12 takes into account at least one further operating state. This may be, for example, the immediately preceding final operating state Z' or a plurality of previous final operating states Z'. Rapid changes in the final operating state Z' can be avoided, for example, by low-pass filtering or similar measures.

It is also possible that the setpoint flow rates Ka* to Kd* are predicted by the model prediction within a prediction period of multiple cycle times, such as 5, 8, or 10 cycle times, thus It is also possible to determine a tentative operating state Z of the pump assembly 5 expected in the future in the forecast period. In this case, the future expected interim operating state Z of the pump assembly 5 can also be included in the determination of the current final operating state Z'.

As part of the embodiment according to FIG. 8, the final operating pressure pAe obtained is lower (generally even if only slightly lower) than the maximum of the individual operating pressures pAa to pAd of steps S2 and S3. ) can happen. Therefore, as part of the embodiment according to FIG. 8, if the limit modulation values kLim of the control valves 11a to 11d are smaller than their maximum possible modulation and/or first of all before considering further operating conditions , a small offset is added to the interim operating pressure pAv, or if the interim operating pressure pAv is scaled by a factor slightly greater than one.

The invention has been described above in conjunction with embodiments in which pump assembly 5 has only a single pump 8 . However, embodiments in which the pump assembly 5 has more than one pump 8 are readily possible. In this case, the pumps 8 are treated as if all pumps 8 are completely stopped and they do not exist, or they are operated to generate the same interim operating pressure pAv and the same final operating pressure pAe. It must be. However, there is flexibility regarding the distribution of the total flow K between the individual pumps 8 . To solve this degree of freedom, it is possible, for example, to distribute the total flow K between the pumps 8 uniformly or in proportion to the pumping capacity of the pumps 8 . Alternatively, it is also possible to have only the minimum possible number of pumps 8 actively run at all times. In this case the header line 4 is fed with a single pump 8 if possible. The next pump 8 only operates when the previously operated pump 8 is no longer able to deliver the requested total flow K at the requested interim operating pressure pAv or the requested final operating pressure pAe. switched on. Similarly, the next pump 8 in each case is such that the previously operated pump 8 no longer delivers the required total flow K at the required interim operating pressure pAv or the required final operating pressure pAe. is switched on only when it is not possible.

The invention has also been described above with respect to a single cooling unit 3 . However, it is readily possible that there are more cooling units 3 . In this case the further cooling unit 3 can be controlled by the control unit 12 or by some other control unit, depending on the requirements. In the case of control by the control unit 12, the cooling units 3 can be operated independently of each other.

The invention has many advantages. In particular, a very low energy consumption is achieved. Savings of at least 25% and sometimes well over 80% are achieved compared to operation of the cooling unit 3 with a constant final operating pressure pAe. Even compared to an approach in which the final operating pressure pAe is individually adapted to each rolled blank 2 and kept at a constant level only during the cooling of the respective rolled blank 2, still significant energy savings are realized. Indeed, it is theoretically conceivable that a reduction in the final operating pressure pAe would result in a significant deterioration in the efficiency of the pump assembly 5 and an increase in energy consumption. However, in practice this does not occur. Furthermore, both the dynamics of the control valves 11a to 11d and the dynamics of the pump assembly 5 are preserved. This is generally because it is advantageous for the control valves 11a to 11d if they are operated to open as wide as possible. Likewise, it is advantageous for the pump assembly 5 if it is run as slow as possible. On the other hand, the cooling of the rolled stock 2 has no adverse effects as such.

Although the invention has been illustrated and described in more detail and more concretely using preferred exemplary embodiments, the invention is not limited by the examples disclosed and goes beyond the scope of protection of the invention. Other variations can be derived therefrom by those skilled in the art.

1 rolling stand 2 rolling stock 3 cooling unit 4 header line 5 pump assembly 6 coolant 7 reservoir 8 pump 9a to 9d branch line 10a to 10d application unit 11a to 11d control valve 12 control unit 13 computer program 14 machine code 15 shunt valve Aa to Ad operating value Amax maximum operating value Amin minimum operating value AP1 to AP3 operating point K total flow ka to kd modulation Ka to Kd coolant flow Ka* to Kd* set point flow kLim limit modulation value KR reference coolant flow KRmax maximum reference coolant flow rate KRmin minimum reference coolant flow rate n rotational speed nmax maximum rotational speed nmin minimum rotational speed pA, pAv, pAe operating pressure pAa to pAd individual operating pressure pR reference pressure pS suction pressure S1 to S41 step Z, Z' operating state δp pressure increase

Claims (8)

An operating method for operating a cooling unit (3) for cooling a hot-rolled material (2) made of metal, comprising:
- said cooling unit (3) has a header line (4), a liquid coolant (6) is supplied to said header line (4) by a pump assembly (5) and a plurality of branch lines ( 9a-9d) branch off from said header line (4) to application units (10a-10d),
- said pump assembly (5) comprises a plurality of pumps (8), a control valve (11a-11d) being arranged in each of said branch lines (9a-9d), said coolant (6 ) is applied to said hot rolled material (2) by at least some of said application units (10a-10d),
- the setpoint flow rates (Ka*-Kd*) to be supplied to said application units (10a-10d) are communicated to the control unit (12) of said cooling unit (3),
- said control unit (12) operates said pump assembly (5) according to a final operating state (Z') and operates said control valves (11a-11d) according to operating values (Aa-Ad); In the driving method,
In order to determine the final operating state (Z') of the pump assembly (5) and the operating values (Aa-Ad) of the control valves (11a-11d), the control unit (12):
- said control such that individual operating pressures (pAa-pAd) predominate in said header lines (4) and said set point flows (Ka*-Kd*) respectively flow through said branch lines (9a-9d) respectively; determining said individual operating pressure (pAa-pAd) of each of said control valves (11a-11d) for a limit modulation value (kLim) of each valve (11a-11d);
- at the same time a total flow (K) of coolant (6) corresponding to the sum of said set point flows (Ka*-Kd*) is supplied by said pump assembly (5) to said header line (4); , the provisional operating pressure (pAv) of said pump assembly (5), which is at least as high as the maximum pressure of said individual operating pressures (pAa-pAd), predominates in said header line (4). determine the desired operating state (Z);
- said total flow (K) of coolant (6) is supplied by said pump assembly (5) to said header line (4) while the final operating pressure (pAe) prevails in said header line (4); using said interim operating state (Z) of said pump assembly (5) to determine said final operating state (Z') of said pump assembly (5) such that
- using the final operating pressure (pAe) of the control valves (11a-11d) such that each of the set point flows (Ka* to Kd*) flows in each of the branch lines (9a to 9d); A method of operation, characterized in that the operating values (Aa-Ad) are determined. The limit modulation value (kLim) of the control valve (11a-11d) is the maximum modulation value of the control valve (11a-11d) or near the maximum modulation value of the control valve (11a-11d) 2. The operating method according to claim 1, wherein the value of . 3. According to claim 1 or 2, characterized in that when determining the interim operating state (Z), the control unit (12) takes into account secondary conditions relating to the pump assembly (5). Driving method as described. 1-, characterized in that when determining the interim operating state (Z), the control unit (12) takes into account secondary conditions relating to the control valves (11a-11d) 4. The operating method according to any one of 3. In determining said final operating state (Z') of said pump assembly (5), said control unit (12) controls at least one previous final operating state (Z') of said pump assembly (5) and/or or at least one provisional operating state (Z) of the pump assembly (5) expected in the future is taken into account. A computer program comprising machine code (14) executed by a control unit (12) of a cooling unit (3) for cooling a hot rolled material (2) made of metal, comprising:
Execution of the machine code (14) by the control unit (12) causes the control unit (12) to operate the cooling unit (3) according to the method of operation according to any one of claims 1 to 5. A computer program that drives. A control unit for a cooling unit (3) for cooling a hot-rolled material (2) made of metal, comprising:
The control unit uses a computer program (13) according to claim 6, such that the control unit operates the cooling unit (3) according to the operating method according to any one of claims 1-5. A control unit that is programmed with A cooling unit for cooling a hot-rolled material (2) made of metal, comprising:
- said cooling unit comprises a header line (4), a pump assembly (5) and a plurality of application units (10a-10d),
- a liquid coolant (6) is applied to said hot rolled material (2) by at least some of said application units (10a-10d),
- said application units (10a-10d) are connected to said header line (4) via respective branch lines (9a-9d),
- said pump assembly (5) comprises a plurality of pumps (8) for supplying said liquid coolant (6) to said header line (4);
- a control valve (11a-11d) is arranged in each of said branch lines (9a-9d),
- a cooling unit comprising a control unit (12) according to claim 7, said cooling unit operating said cooling unit according to an operating method according to any one of claims 1-5.

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